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Highlights The objective of this study is to improve the properties of polylactic acid (PLA), a biopolymer produced from renewable resources, without compromising its environmentally friendly “natural composite” properties. The aim was to expand the application range of PLA by making it suitable for the production of high performance composites. With this in mind, it was decided to use inorganic and environmentally friendly materials such as basalt fiber (BF) and boric acid (BA) as reinforcements. Adhesive wear and tensile tests were used to investigate the tribological and mechanical performance of the composites. Differential scanning calorimetry (DSC) and dimensional stability analysis (DSA) methods were used to investigate the thermal properties. Scanning electron microscopy analysis was also used to investigate the morphological properties of the samples. In addition, a matrix modification process using Joncryl®, an epoxy‐based chain extender chemical, was applied to enhance the interfacial interaction between the composite components and improve the composite properties by improving the dispersion of reinforcing materials. As a result of the characterization tests, it was observed that a significant improvement in the properties of the material type containing 10 wt% BF, 0.25 wt% BA and 2 wt% Joncryl® was achieved. A 19% increase in tensile strength of this type of material was observed compared with unreinforced PLA, while the sharp peak increase in the coefficient of friction (COF) curve was shifted from 20 m to 60 m. As a result, it has been presented that environmentally friendly and inorganic materials such as BF and BA can be used to produce composite materials that will serve sectors where the need and use of high performance materials is intense, especially in the automotive, aerospace and aviation sectors. The properties of PLA matrix composites were improved by the simultaneous use of BF and BA and the addition of Joncryl®. The structural properties of PLA, an environmentally friendly polymer, have been improved without compromising this characteristic. PLA matrix natural composites with performance that can be used in the automotive, aerospace and aviation sectors have been developed. [ABSTRACT FROM AUTHOR]

Polymer biocompositions of poly(3-hydroxybutyrate) (P3HB) and linear polyurethanes (PU) with aromatic rings were produced by melt-blending at different P3HB/PU weight ratios (100/0, 95/5, 90/10, and 85/15). Polyurethanes have been prepared with 4,4′-diphenylmethane diisocyanate and polyethylene glycols with molar masses of 400 g/mol (PU400), 1000g/mol (PU1000), and 1500 g/mol (PU1500). The compatibility and morphology of the obtained polymer blends were determined by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The effect of the polyurethane content in the biocompositions on their thermal stability and mechanical properties was investigated and compared with those of the native P3HB. It was shown that increasing the PU content in P3HB-PU compositions to 10 wt.% leads to an improvement in the mentioned properties. The obtained results demonstrated that the thermal stability and mechanical properties of P3HB were improved, particularly in terms of increasing the degradation temperature, reducing hardness, and increasing impact strength. The best thermal and mechanical properties were shown by the P3HB-PU polymer compositions containing 10 wt.% of polyurethane modifiers, especially PU1000, which was also confirmed by the morphology analysis of these biocompositions. The presence of polyurethanes in the resulting polymer biocomposites decreases their glass transition temperatures, i.e., makes the materials more flexible. The resulting polymer biocompositions have suitable mechanical properties and thermal properties within the processing conditions for the predicted application as biodegradable, short-lived products for agriculture. [ABSTRACT FROM AUTHOR]

Medicated jellies are widely used by a large part of patients, especially by people with swallowing difficulties. Preformulation studies play an essential role in the development of new pharmaceutical formulations. The present study aimed to formulate and evaluate medicated jellies containing perphenazine, an antipsychotic drug from the group of phenothiazine compounds used to treat schizophrenia and other mental disorders. Typical gelling agents such as sodium alginate (Alg), gelatine (Gel), and pectin (Pec) were used to develop the medicated jellies. In addition to the biopolymers, components such as benzoic acid (BenzAc), citric acid (CitAc), sodium citrate (NaCit), sorbitol (Sorb) and xylitol (Xyl) were also used. Before preparing the jellies, the moist binary mixture between each component of the jelly and the active substance was analysed to investigate the compatibility of the substances. The active substance, moist binary mixture, and medicated jellies were analysed by FTIR_UATR spectroscopy, UV-Vis spectroscopy and thermogravimetry. [ABSTRACT FROM AUTHOR]

Due to the growing interest in biopolymers, biosynthesizable and biodegradable polymers currently occupy a special place. Unfortunately, the properties of native biopolymers make them not good enough for use as substitutes for conventional polymers. Therefore, attempts are being made to modify their properties. In this work, in order to improve the properties of the poly(3-hydroxybutyrate) (P3HB) biopolymer, linear aliphatic polyurethane (PU) based on 1,4-butanediol (BD) and hexamethylene 1,6-diisocyanate (HDI) was used. The conducted studies on the effect of the amount of PU used (5, 10, 15 and 20 m/m%) showed an improvement in the thermal properties of the prepared polymer blends. As part of the tested mechanical properties of the new polymer blends, we noted the desired increase in the tensile strength, and the impact strength showed a decrease in hardness, in particular at the presence of 5 m/m% PU. Therefore, for further improvement, hybrid nanobiocomposites with 5 m/m% PU and organically modified montmorillonite (MMT) (Cloisite 30®B) were produced. The nanoadditive was used in a typical amount of 1–3 m/m%. It was found that the obtained nanobiocomposites containing the smallest amount of nanofillers, i.e., 1 m/m% Cloisite®30B, exhibited the best mechanical and thermal properties. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced polymer composites are presently receiving the attention of scholars and industrialists due to their specific properties, such as being naturally eco-friendly, biodegradable, economical, viable, available, and sustainable. The key problems associated with natural fiber polymer composites, including fiber/matrix compatibility, high moisture absorption, and, especially, thermal degradation in engineering plastics (high-temperature plastics), constitute the most critical thrust of this review. It is noted that at high temperatures, natural fibers degrade and this has adversely restricted their usage with only commodity thermoplastics having relatively low melting temperatures, such as polypropylene (PP) and polyethylene (PE). This review paper, therefore, provides valuable research highlights on utilizing and improving the mechanical and thermal properties of natural kenaf fibers as reinforcement in engineering polymer composites for high-temperature engineering applications using polymer matrices, such as polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), and polyphenylene ether (PPE). The initial and various chemical treatments of natural fibers, their effect on the thermal and performance properties of natural fiber engineering thermoplastic composites, and the advanced treatment of epoxy coatings are reviewed. Applications of natural fiber-reinforced thermoplastic composites in the construction and automotive industries, as well as in other applications, are outlined. It was established that the adhesion and thermal stabilities between polymer matrix and natural fibers are better improved by surface coating with diluted epoxy resin thermoset. This eventually improved the overall thermal and performance properties of the resultant composites and will serve as a data bank and guide for manufacturers and future research directions using high-end engineering polymers with higher processing temperatures. [ABSTRACT FROM AUTHOR]

Nanocellulose derived from cellulose, the abundant natural polymer, is used in various applications due to its superior chemical, mechanical and thermal properties along with good biocompatibility and biodegradability. This paper reports an investigation of the extraction of nanocellulose from two freely available natural precursors-watermelon rinds and water hyacinth leaves. Cellulose isolation was carried out through chemical methods, including acid and alkali treatments followed by bleaching. The chemical composition, percentage crystallinity and particle size were studied using various characterization techniques. FTIR spectra indicate the removal of hemicelluloses, pectin, and lignin resulting in the effective isolation of cellulose from both precursors. Results of XRD indicate a high concentration of Cellulose Nanocrystals (CNCs) in the treated sample. The FESEM and SEM-EDAX images also confirm the formation of CNCs. TGA and DSC results show excellent thermal stability for both CNCs. Investigations on the properties of a CNC-reinforced epoxy composite are also reported. Results indicate considerable improvement in the mechanical properties, thermal stability and thermal conductivity of the composites compared to the pristine polymer. [ABSTRACT FROM AUTHOR]

Natural and biodegradable polymers with pH-responsive properties, such as alginate and chitosan, are widely exploited for drug delivery applications, most notably in the form of biocompatible microspheres. In addition, thermo-responsive poly(N-isopropyl-acrylamide) (PNIPAM) is often added to biomedical delivery systems due to its lower critical solution temperature close to human physiological conditions. In this work, multi-responsive microspheres (MRMs) consisting of a hydrogel matrix made of alginate, chitosan, and PNIPAM were successfully prepared by extrusion dripping and proposed as delivery system for Ozoile (Stable Ozonides) derived from biological olive oil. Ozoile acts as a biological inducer, regulating the main metabolic pathways and stimulating the endogenous defence system. The MRMs containing Ozoile were prepared from alginate/NIPAM emulsions integrating the lipophilic bioactive principle. The MRMs were further optimised with a chitosan coating to improve their stability and control the degradation behaviour of the hydrogel matrix, with subsequent release of Ozoile. Results in terms of chemical composition from Fourier transform infrared (FTIR) spectroscopy, thermo-responsive properties from differential scanning calorimetry (DSC) analysis, swelling and degradation behaviour were used to establish the potential use of the MRMs for the therapeutic release of Ozoile at specific inflammatory sites. [ABSTRACT FROM AUTHOR]

Hybrid polymer composites are utilized in biomechanical design and orthopedic surgery training to imitate the thermomechanical behavior of human bones. Despite extensive research on the mechanics of hybrid composites in biomechanical design, information on their thermomechanical response during orthopedic drilling operations is scarce. This paper presents a new experimental study to characterize the force and temperature generated during the drilling of hybrid composites that simulate human bones. To simulate the hybrid multi-layer structure of bones, the studied composite comprises a Polyurethane core sandwiched between Glass-Fiber Reinforced Polymer (GFRP) layers—the former resembling the cancellous part of the bone and the latter cortical layers. This study also identifies an empirical relationship between thrust force, temperature, drilling feed and speed, and composite composition. Empirical models are developed using multivariate polynomial regression (MPR) and artificial neural network (ANN) to predict the force and temperature during drilling. The models have a correlation coefficient of above 0.9 between predicted and measured results and can be used to improve orthopedic drilling design and control. [ABSTRACT FROM AUTHOR]

The current research is devoted to the investigation of the plasticization of polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-hydroxyvalerate (PHBV) with triethyl citrate (TEC). Three different PHB or PHBV-based systems with 10, 20, and 30 wt.% of TEC were prepared by two-roll milling. The effect of TEC on the rheological, thermal, mechanical, and calorimetric properties of the developed compression-molded PHB and PHBV-based systems was determined. It was revealed that the addition of TEC significantly influenced the melting behavior of both polyhydroxyalkanoates (PHA), reducing their melting temperatures and decreasing viscosities. It was also revealed that all the investigated systems demonstrated less than 2% weight loss until 200 °C and rapid degradation did not occur until 240–260 °C in an oxidative environment. Apart from this, a remarkable increase (ca 2.5 times) in ultimate tensile deformation εB was observed by increasing the amount of TEC in either PHB or PHBV. A concomitant, considerable drop in ultimate strength σB and modulus of elasticity E was observed. Comparatively, the plasticization efficiency of TEC was greater in the case of PHBV. [ABSTRACT FROM AUTHOR]

This paper explores the effect of nanoclay for improving the interfacial properties of starch bioplastic material filled with cellulose-nanoparticles (CNPs). The CNPs were prepared through acid-hydrolysis process by using acid concentration to break the amorphous region of chopped fiber to produce nano-cellulose. Various CNPs concentration (0.5 – 2.5 wt.%) were dispersed in cornstarch biopolymer matrix to form bioplastic films through solution casting method and listed for thermal and mechanical properties. Cornstarch bioplastic filled with 1.5 wt.% of CNPs showed optimum improvement in thermal and mechanical properties. Furthermore, nanoclay (NC) of varying weight percentage (0.1 – 0.5 wt. %) were added to the optimum improved 1.5 wt.% CNPs filled cornstarch bioplastic material. Hence, the hybrid cellulose-nanoparticles/nanoclay (CNPs/NC) filled cornstarch was improved both thermally and mechanically. The stiffness parameter ( β f ) and confinement region (C ) of the bioplastic during relaxation stage were 0.70 and 1.03 respectively for hybrid fillers at 1.5/0.3_CNPs/NC, which is an indication that nanoclay had a very good reinforcing effect on the starch polymer system. Improved tensile modulus and tensile strength of the CNPs/NC by 639% and 97% respectively were found when compared to CNPs filled cornstarch bioplastic material. Furthermore, the addition of nanoclay slow down the effect of water absorption rate. Hence, the water uptake of the bioplastic film was normalized. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is being used more widely because of the simplicity of the operating procedures. It decreases material consumption during part production and eliminates material waste. Fused deposition modeling (FDM), a well‐known AM process, uses thermoplastic polymer as a feedstock to manufacture the end design. Pure thermoplastic‐based products are still utilized as prototypes in several sectors due to their lack of strength and durability. This problem has been solved by strengthening the thermoplastics by adding a reinforcing element. Composites are made of polymers and various constituents known as reinforcing components. This article overviews natural reinforced polymer composites used in the FDM process. Mechanical and Thermal properties are presented based on natural filler percentage, and this article only considered natural composite filaments for the FDM process. [ABSTRACT FROM AUTHOR]

Highly methylated apple pectin (HMAP) and pork gelatin (PGEL) have been proposed as gelling agents for pumpkin purée-based films. Therefore, this research aimed to develop and evaluate the physiochemical properties of composite vegetable films. Granulometric analysis of film-forming solutions showed a bimodal particle size distribution, with two peaks near 25 µm and close to 100 µm in the volume distribution. The diameter D4.3, which is very sensitive to the presence of large particles, was only about 80 µm. Taking into account the possibility of creating a polymer matrix from pumpkin purée, its chemical characteristic was determined. The content of water-soluble pectin was about 0.2 g/100 g fresh mass, starch at the level of 5.5 g/100 g fresh mass, and protein at the level of about 1.4 g/100 g fresh mass. Glucose, fructose, and sucrose, the content of which ranged from about 1 to 1.4 g/100 g fresh mass, were responsible for the plasticizing effect of the purée. All of the tested composite films, based on selected hydrocolloids with the addition of pumpkin purée, were characterized by good mechanical strength, and the obtained parameters ranged from about 7 to over 10 MPa. Differential scanning calorimetry (DSC) analysis determined that the gelatin melting point ranged from over 57 to about 67 °C, depending on the hydrocolloid concentration. The modulated differential scanning calorimetry (MDSC) analysis results exhibited remarkably low glass transition temperature (Tg) values, ranging from −34.6 to −46.5 °C. These materials are not in a glassy state at room temperature (~25 °C). It was shown that the character of the pure components affected the phenomenon of water diffusion in the tested films, depending on the humidity of the surrounding environment. Gelatin-based films were more sensitive to water vapor than pectin ones, resulting in higher water uptake over time. The nature of the changes in water content as a function of its activity indicates that composite gelatin films, with the addition of pumpkin purée, are characterized by a greater ability to adsorb moisture from the surrounding environment compared to pectin films. In addition, it was observed that the nature of the changes in water vapor adsorption in the case of protein films is different in the first hours of adsorption than in the case of pectin films, and changes significantly after 10 h of the film staying in an environment with relative humidity RH = 75.3%. The obtained results showed that pumpkin purée is a valuable plant material, which can form continuous films with the addition of gelling agents; however, practical application as edible sheets or wraps for food products needs to be preceded with additional research on its stability and interactions between films and food ingredients. [ABSTRACT FROM AUTHOR]

Chitosan is one of the most commonly employed natural polymers for biomedical applications. However, in order to obtain stable chitosan biomaterials with appropriate strength properties, it is necessary to subject it to crosslinking or stabilization. Composites based on chitosan and bioglass were prepared using the lyophilization method. In the experimental design, six different methods were used to obtain stable, porous chitosan/bioglass biocomposite materials. This study compared the crosslinking/stabilization of chitosan/bioglass composites with ethanol, thermal dehydration, sodium tripolyphosphate, vanillin, genipin, and sodium β-glycerophosphate. The physicochemical, mechanical, and biological properties of the obtained materials were compared. The results showed that all the selected crosslinking methods allow the production of stable, non-cytotoxic porous composites of chitosan/bioglass. The composite with genipin stood out with the best of the compared properties, taking into account biological and mechanical characteristics. The composite stabilized with ethanol is distinct in terms of its thermal properties and swelling stability, and it also promotes cell proliferation. Regarding the specific surface area, the highest value exposes the composite stabilized by the thermal dehydration method. [ABSTRACT FROM AUTHOR]

The study developed and designed polyvinyl acetate (PVAc) foams using advanced freeze-drying technology, which exhibited good heat-insulating ability, flame retardancy, and mechanical properties. Different combinations of bleach kraft pulp, water-soluble chitosan, and zinc borate were used to reinforce the foams. The foams exhibited desirable compression and flexural properties, with compression strength and compression modulus ranging from 0.01 MPa to 0.08 MPa and 0.05 MPa to 0.29 MPa, respectively, while flexural strength and flexural modulus ranged from 0.12 MPa to 5.37 MPa and 9.86 MPa to 260,85 MPa, respectively. The use of zinc borate as a reinforcement resulted in improved thermal properties and reduced mass loss at 600°C by 20.69%. Thermal conductivity tests indicated that the foams had low thermal conductivity values ranging from 0.037 W/mK to 0.074 W/mK. The foams with zinc borate (60 g /L) and high molecular weight water-soluble chitosan (70 g /L) reinforcement exhibited high limiting oxygen index (LOI) of 28.72%. Overall, the results suggest that the PVAc foams could serve as a promising sustainable alternative in thermal insulation and construction fields. [ABSTRACT FROM AUTHOR]

Oriented polylactic acid (PLA)/graphene oxide (GO) nanosheets tapes were prepared via uniaxial solid state drawing. The effect of various drawing conditions, including drawing ratio (DR), temperature (DT), and speed (DS) on mechanical, thermal, structural, and barrier properties were studied. Structural studies showed oriented structure for the drawn tapes with aligned polymer chains and GO nanosheets. Differential scanning calorimetry revealed improved glass transition temperature (Tg) and crystallinity (Xc) after drawing. In addition, Tg and Xc were increased more by increasing DR and DT. The highest Tg and Xc were achieved for 3/70/50 tape with values of 73°C and %22, respectively. Higher thermal stabilities and enhanced barrier properties were achieved after drawing, especially at the higher DR. Finally, tensile testing revealed simultaneous improvement in stiffness and toughness due to strain hardening for all the drawn tapes. The strength and elastic modulus were increased after increasing DR, DS, and DT and reached the highest values of 149 MPa and 3.6 GPa for 3/70/50. Overall, the properties were controllable by the processing conditions. [ABSTRACT FROM AUTHOR]

This work focused on the preparation of biopolymer blend nanocomposites from chitin (CT) and cashew tree gum (CTG) with different contents of copper sulphide nanoparticles (CuS) by solution casting method. The formation of nanocomposites have been characterized by FT infrared (FTIR), UV spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), thermogravimetry (TGA), differential scanning calorimetry (DSC) and impedance analysis. The characteristic absorption of nanoparticles in the FTIR spectra and shift in UV spectra of blend composites revealed the strong interaction between CuS nanoparticles and the polar segments of CT/CTG blend. With the increase in dosage of nanoparticles, a decrease in amorphous domains has been noted in the XRD scans. The uniform distribution of nanoparticles in CT/CTG network has been confirmed by the SEM analysis. HRTEM of the blend composites reveals the formation of hemispherical nanoparticles with a diameter of 15–30 nm. The glass transition temperature of blend composites increased with the addition of nano-CuS in the polymer matrix. Compared to the pure CT/CTG blend, the prepared nanocomposite showed higher thermal stability. Mechanical properties such as tensile strength and hardness of the blend nanocomposites were greatly enhanced by the reinforcement of CuS into the CT/CTG matrix. The AC conductivity and dielectric properties of the nanocomposites increased with the concentration of fillers and the magnitude of these properties was higher than the pure polymer blend. [ABSTRACT FROM AUTHOR]

Research in bio-based composites is rapidly rising in terms of fundamental experiments and industry applications. Natural fibres are one of the common bio-based materials used in composites. Natural fibres have many advantages, including low cost, biodegradable, good thermal conductivity, and may also be used as an alternative to synthetic polymer composites. However, the hydrophilic characteristic of natural fibres can lead to poor interfacial adhesion between natural fibres reinforced and matrix phases, which can affect the properties of bio-based composites. To overcome this problem, the surface modification of natural fibres is required to improve the hydrophobic properties of the composite. A few studies revealed that silane improved the hydrophobicity, tensile strength and thermal stability of bio-based composites. The highest water contact angle of the treated bio-based composite was reported at 135°. Meanwhile, the tensile strength of silane-treated bio-based composite can increase up to 40%. The onset decomposition temperature of silanes treated with bio-based composite is 20 ° C higher compared to untreated bio-based composite. This article provides an insightful review of the surface treatment of bio-based composites via silane treatment on mechanical properties, thermal properties, water absorption, and water contact angle. [ABSTRACT FROM AUTHOR]

Despite the fact that amino cellulose (AC) is biodegradable, biocompatible, and has excellent film-forming properties, AC films have poor mechanical properties and are not thermally stable. An AC-based composite film prepared from AC and curcumin-stearylamine based benzoxazine (C-st) is reported in order to improve its performance and promote its application. As starting materials, C-st and AC were used to produce a C-st/AC composite film possessing a synergistic property through chemical cross-linking and hydrogen bonds. Two salient features with respect to the curing behavior were obtained. Firstly, the onset of curing was reduced to 163 °C when the benzoxazine monomer was synthesized from fully bio-based precursors (such as curcumin and stearylamine). Secondly, a synergistic effect in curing behavior was obtained by mixing C-st with AC. As a result of tensile tests and thermal analysis, the poly(C-st) benefited the composite films with pronounced mechanical and thermal properties, even at elevated temperatures. There was a 2.5-fold increase in tensile strength compared to the AC film, indicating that the composite films have the potential to be used for functional purposes. These poly(C-st)/AC films with improved mechanical and thermal properties have the ability to replace naturally occurring polymer films in film-related applications. [ABSTRACT FROM AUTHOR]

Toughening efficiency of poly(ethylene-n-butylene-acrylate-co-glycidyl methacrylate) (EBA-GMA) in poly(lactic acid) (PLA) matrix has been found to significantly increase at elevated blending temperature. In the case of PLA/EBA-GMA blends having 10.0 or 12.5 wt% EBA-GMA contents, the accelerated PLA degradation at raised processing temperature resulted in reduced mechanical performance. At 15.0 wt% EBA-GMA ratio, however, increased elongation and by 250% improved notched Izod impact strength was achieved when the blending temperature was raised from 240 to 260 °C. This beneficial effect is attributed to the accelerated compatibilization reactions between the components in the presence of shortchain PLA molecules, which allow the rapid formation of a toughening enhancer interphase (TEI) during melt processing. As a result, the brittle-ductile transition can be reached at lower elastomer content than expected. Decreased melt flow index (MFI) values besides stabilized blend morphology indicated efficient PLA--EBA-GMA compatibilization at elevated processing temperature. Accordingly, enhanced nucleation ability of the PLA/EBA-GMA interphase and hindered chain crystallization of PLA were found by differential scanning calorimetry (DSC) analyses. In association with the intensified compatibilization reactions cross-linking of the terpolymer was also revealed using the thermally stimulated depolarization current (TSDC) technique. [ABSTRACT FROM AUTHOR]

With the increase in environmental pollution, studies on the use of sustainable resources are increasing day by day. For this purpose, the use of natural fiber-reinforced polymer composites is encouraged in many areas such as automotive, transportation, construction, and home textiles. However, they are flammable and therefore seriously threaten the safety of people and property. Various flame retardant additives have been used to improve the flame retardancy properties of these composites. In this study, silicon dioxide (SD) and zinc borate (ZB) microparticles in different weight percentages (3, 5, 7, and 10%) were reinforced to give flame retardant properties to jute-epoxy composites. In addition, composites containing both SD and ZB microparticles were produced and they were labeled as HB. Then, thermal conductivity, flammability, water absorption, and mechanical properties of these composites were investigated. The burning rate of the composites decreased as the amount of microparticle increased. 5ZB5SD, including %5 SD and %5 SD microparticles, showed 36.60% less burning rate than the neat jute-epoxy composite. 5ZB showed 10.84% higher tensile strength than the neat juteepoxy. The impact strength of the specimens increased with the increase in the filling ratio, and 5ZB5SD showed approximately 2.50 times the impact strength of the jute-epoxy composite. [ABSTRACT FROM AUTHOR]

Recently, the global demand for plastics rose to its maximum mainly due to the rapid increase in population and the growing demand for automobiles. The mass production and disposal of synthetic fiber-based composites pollutes the environment and emission of greenhouse gases. Natural fibers prove to be a suitable alternative to synthetic fibers and the green composites made by reinforcing them with biopolymers find widespread use in various engineering applications. In this paper, the physico-chemical, mechanical, and thermal properties of novel cellulosic fibers extracted from the bark of Madhuca longifolia tree have been investigated through standard test procedures. Test results revealed the presence of cellulose (50.64 wt.%), lignin (17.44 wt.%), and wax (0.60 wt.%) in Madhuca longifolia fiber (MLF). High strength, high rigidity, and better interfacial bonding characteristics with polymer matrix results due to the presence of these chemical constituents. Lower density (1510 kg/m3) and higher activation energy (67.04 kJ/mol) make MLF suitable for making lightweight green composites. The tensile strength and modulus of MLF were found to be 140.96-317.50 MPa and 4.29-5.90 GPa, respectively. The morphology of MLF surface examined through FESEM images revealed the existence of a rough, porous surface, which is essential for making biodegradable composites. [ABSTRACT FROM AUTHOR]

Recent years have observed a significant increase in the use of degradable materials in medicine due to their minimal impact on the patient and broad range of applicability. The biodegradable polymer Polydioxanone (PDO) provides a good example of the use of such one polymer that can represent the aforementioned medical materials in the field of medicine, due to its high level of biocompatibility and interesting mechanical properties. PDO is used to produce absorbable medical devices such as sutures and stents, and is also suitable for the fabrication of certain orthopedic implants. Polydioxanone can be processed using the injection molding method due to its thermoplastic nature; this method allows for the precise and easily-controllable production of medical materials without the need for toxic additives. A number of small commercial polymer implants have recently been introduced onto the market based on this processing method. It is important to note that, to date, no relevant information on the molding of PDO is available either for the scientific or the general public, and no study has been published that describes the potential of the injection molding of PDO. Hence, we present our research on the basic technological and material parameters that allow for the processing of PDO using the laboratory microinjection molding method. In addition to determining the basic parameters of the process, the research also focused on the study of the structural and mechanical properties of samples based on the thermal conditions during processing. A technological frame work was successfully determined for the processing of PDO via the microinjection molding approach that allows for the production of samples with the required homogeneity, shape stability and surface quality in a laboratory scale. The research revealed that PDO is a polymer with a major share of crystalline phases, and that it is sensitive to the annealing temperature profile in the mold, which has the potential to impact the final crystalline structure, the fracture morphology and the mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, the development of nanocomposite systems based on reduced graphite oxide (rGO) was combined with the development of crosslinked materials characterized by dynamic covalent bonds, i.e., a covalent associative network, starting from ad-hoc synthesized hydroxyl terminated polycaprolactone (PCL-OH). The crosslinking reaction was carried out using methylenediphenyl diisocyanate (MDI) to create systems capable of bond exchanges via transesterification and transcarbamoylation reactions, in the presence of stannous octoate as a catalyst. The above materials were prepared at two different temperatures (120 and 200 °C) and two PCL-OH:MDI ratios. FT-IR measurements proved the formation of urethane bonds in all the prepared samples. Crosslinking was demonstrated by contacting the samples with a solvent capable of dissolving the star-shaped PCL. These tests showed a significant increase in the crosslinked fraction with increasing the temperature and the PCL-OH:MDI ratio. In order to evidence the effect of crosslinking on rGO dispersion and the final properties of the material, a nanocomposite sample was also prepared using a linear commercial PCL, with the nanofiller mixed under the same conditions used to develop the crosslinked systems. The dispersion of rGO, which was investigated using FE-SEM measurements, was similar in the different systems prepared, indicating that the crosslinking process had a minor effect on the dispersibility of the nanofiller. As far as the thermal properties are concerned, the DSC measurements of the prepared samples showed that the crosslinking leads to a decrease in the crystallinity of the polymer, a phenomenon which was particularly evident in the sample prepared at 200 °C with a PCL-OH: MDI ratio of 1:1.33 and was related to the decrease in the polymer chain mobility. Moreover, rGO was found to act as a nucleating agent and increase the crystallization temperature of the nanocomposite sample based on linear commercial PCL, while the contribution of rGO in the crosslinked nanocomposite samples was minor. Rheological measurements confirmed the crosslinking of the PCL-OH system which generates a solid-like behavior depending on the PCL-OH:MDI ratio used. The presence of rGO during crosslinking generated a further huge increase in the viscosity of the melt with a remarkable solid-like behavior, confirming a strong interaction between rGO and crosslinked PCL. Finally, the prepared nanocomposites exhibited self-healing and recyclability properties, thus meeting the requirements for sustainable materials. [ABSTRACT FROM AUTHOR]

In this paper, chitosan (Chi) was successfully reacted with natural mono ketone namely, camphor (Cam), through a condensation reaction to obtain a novel Chi-Cam polymer. The encapsulation of Chi-Cam polymer into the cavity of β-cyclodextrin biopolymer by inclusion complex method, and the immobilization of TiO 2 NPs into Chi-Cam matrix by metal complex method were performed. A set of characterizations (XRD, FTIR, SEM, UV–Vis., optical band gap, Urbach energy, refractive index, and thermogravimetric analysis) were implemented to incorporate their properties with applications. It was not observed the existence of any strange peaks in diffractogram patterns of all prepared samples, confirming the proper preparation and high purity polymers. The crystalline index was found to be 69.41, 41.58, 58.25 and 44.2 % for Chi, Chi-Cam, polyrotaxane, and nanocomposite, respectively. High surface area, lowest pores size, and lowest pores volume were confirmed the micropores of composite, which also could provide more reactive sites, and enhancing the bioactivity. The tested Chi-Cam/TiO 2 NPs possessed the highest antimicrobial impact, followed by the Chi-Cam/β-CD towards pathogenic microbes. The highest % inhibition of biofilm formation by Chi-Cam, Chi-Cam/β-CD, and Chi-Cam/TiO 2 NPs was noted for S. aureus (40.05 %, 80.21 %, and 87.49 %), E. coli (38.56 %, 74.32 % and 83.32 %), P. aureginosa (32.12 %, 58.80 %, and 74.53 %), and C. albicans (13.69 %, 27.89 % and 70.89 %), respectively. The obtaining findings pave the route towards useful utilization of potential materials for biomedical applications. [ABSTRACT FROM AUTHOR]

In 2021, global petroleum-based plastic production reached over 400 million metric tons (Mt), and the accumulation of these non-biodegradable plastics in the environment is a worldwide concern. Polyhydroxybutyrate (PHB) offers many advantages over traditional petroleum-based plastics, being biobased, completely biodegradable, and non-toxic. However, its production and use are still challenging due to its low deformation capacity and narrow processing window. In this work, two linear-chain polyester oligomers were used as plasticizers to improve the processability and properties of PHB. Thermal analyses, XRD, and polarized optical microscopy were performed to evaluate the plasticizing effect on the PHB and the reflection on the mechanical behavior. Both oligomers acted as PHB plasticizers, with a reduction in Tg and Tm as a function of the plasticizer concentration, which can make it easier to handle the material in thermal processing and reduce the probability of thermal degradation. Plasticizer 2 proved to be the most promising between the two with an optimized condition of 20%, in which there was a decrease in elastic modulus of up to 72% and an increase in the maximum elongation of 467%. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with various 3-hydroxyvalerate (3HV) contents biosynthesized by mixed microbial consortia (MMC) fed fermented dairy manure at the large-scale level was assessed over a 3-month period. The thermal, mechanical, and rheological behavior and the chemical structure of the extracted PHBV biopolymers were studied. The recovery of crude PHBV extracted in a large Soxhlet extractor with CHCl3 for 24 h ranged between 20.6% to 31.8% and purified to yield between 8.9% to 26.9% all based on original biomass. 13C-NMR spectroscopy revealed that the extracted PHBVs have a random distribution of 3HV and 3-hydroxybutyrate (3HB) units and with 3HV content between 16% and 24%. The glass transition temperature (Tg) of the extracted PHBVs varied between −0.7 and −7.4 °C. Some of the extracted PHBVs showed two melting temperatures (Tm) which the lower Tm1 ranged between 126.1 °C and 159.7 °C and the higher Tm2 varied between 152.1 °C and 170.1 °C. The weight average molar mass of extracted PHBVs was wide ranging from 6.49 × 105 g·mol−1 to 28.0 × 105 g·mol−1. The flexural and tensile properties were also determined. The extracted polymers showed a reverse relationship between the 3HV content and Young's modulus, tensile strength, flexural modulus, and flexural strength properties. [ABSTRACT FROM AUTHOR]

Commercial available filaments made from poly(lactic) acid (PLA) are selected for potential use in 3D printed parts by fused deposition modeling. Virgin materials (PLA Eum, Z‐PLA Pro), but also recycled matrices (PLA 2Life, PLA Eubio), and one filled with wood fibers (PLA Woodfir) have been considered. Then, a lab‐made filament (PLA Nature) is realized by extruding PLA pellets. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and rheological measurements are used to determine initial degradation temperature, glass transition, melting temperature, and complex viscosity as a function of time and material pre‐drying. A preliminary investigation of thermal properties enables the materials' processing window to be validated in order to prevent the deterioration during the process. PLA Nature and PLA Woodfir melt around 170°C, whereas all of the other biopolymers show a lower melting point (around 150°C). The temperature at which thermal degradation began is always greater than 260°C. However, good stability of rheological parameters over time at 210°C is not confirmed for all bio‐filaments. In particular, for Z‐PLA Pro and PLA Eubio, a significant reduction of complex viscosity is verified after a few seconds of testing. Drying samples have been shown to improve the long‐term stability of complex viscosity. [ABSTRACT FROM AUTHOR]

In this work, new furan-based poly(ester amide)s of various compositions were synthesised by the melt polycondensation method. The chemical structure and composition were determined by nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared (FTIR) analyses. The optical properties were studied by UV-Vis spectroscopy. The thermal properties were investigated by means of differential scanning calorimetry (DSC). The thermo-oxidative stability of PEAs was also tested. Additionally, the free volume by positron annihilation lifetime spectroscopy (PALS) technique and mechanical properties were examined. It was found that the incorporation of poly(propylene furanamide) (PPAF) units significantly affects the thermal and mechanical properties of co-polymers based on poly(hexylene 2,5-furandicarboxylate) (PHF). Depending on the composition, both semi-crystalline and amorphous co-polymers were obtained. Moreover, the values of the free volume radius (R) and the free volume fractions (fv) were strongly affected by the mole fraction of PPAF units. [ABSTRACT FROM AUTHOR]

This work deals with the preparation and the study of a new composite obtained from a thermoplastic polymer and a vegetal fiber. The polymer used is a recycled polyvinylchloride (PVC) and the fiber used was extracted from Agave americana, a plant which grows easily under Mediterranean type climates. Prior chemical treatment of the extracted fiber was necessary to modify the surface of the fiber in order to optimize the adhesion between this fiber and the recycled PVC during the preparation of composites from these materials. For this purpose, our investigations led us to attempt various reactions modification of the surface fiber. The method that gave the best results consists of an alkaline treatment followed by a reaction with acetic anhydride. Once completed chemicals treatments of fiber, the material is mixed with the recycled PVC which serves as a matrix to prepare composites at varying rates from 5% to 30% by weight of agave modified fibers. The effects of the incorporation of raw and processed agave fibers on the mechanical, thermal and morphological properties of PVC/agave fiber composites were examined and discussed. [ABSTRACT FROM AUTHOR]

Application of natural fiber‐polymer composites (NFPCs) in different industrial applications provides competitive edge due to their lightweight, higher specific mechanical properties than glass fibers, sustainability, and lower cost involved in production. There are certain challenges associated with natural fibers and their reinforcement in composites such as poor bonding between the fibers and matrix due to their contradictory nature of characteristics, moisture absorption, lower thermal properties, and poor interfacial adhesion between the natural fiber and polymer matrix. The challenges involved in NFPCs need to be overcome to produce materials with relatively equivalent properties to those of conventional composites and other metallic structures. Several researchers around the globe have conducted investigations with the primary attention being paid to the modification of natural fibers and matrix by employing surface treatments and other chemical treatment methods. In order to address the need for eco‐friendly and sustainable materials in different domains, a comprehensive review on natural fibers and their sources, available matrix materials, modification techniques, mechanical and thermal properties of NFPCs, is needed for better understanding of the behavior of NFPCs. This work provides the information and holistic view of natural fiber‐reinforced composites based on the results obtained from modification techniques, with the view of focusing the review in terms of different chemical and physical treatment techniques, modification of fibers and matrix, and enhanced mechanical and thermal properties in the composites. [ABSTRACT FROM AUTHOR]

Poly(3−hydroxybutyrate−co−3−hydroxyhexanoate) (PHBH) films were prepared using a cast film technique. Dioxane was chosen over other polymer solvents as it resulted in homogenous films with better morphology. Several plasticizers with different molecular weights and concentrations were added to the biopolymer solution prior to casting. Thermal, crystalline, and permeability properties were analyzed by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X−ray diffraction (XRD), and both water vapor and oxygen transmission rate analysis. In general, the addition of plasticizers decreased the glass transition temperature (Tg), cold crystallization temperatures (Tcc), melting temperatures, as well as crystallinity degrees and increased the crystallite sizes and water vapor and oxygen transmission rates. The use of isosorbide and low-molecular-weight poly(ethylene glycol) (PEG) lowered the Tg around 30 °C at the highest used concentration, also being the most effective in increasing the crystallite size. When considering isosorbide and low-molecular-weight poly(ethylene glycol) (PEG) as very good plasticizers for PHBH, the question of which plasticizer to use strongly relies on the desired PHBH application. [ABSTRACT FROM AUTHOR]

The growing awareness of socioeconomic and environmental issues and the high percentage of petroleum resources consumed and new environmental regulations have fueled efforts to develop innovative, cutting-edge, environmentally friendly materials with a wide range of applications. Due to environmental and sustainability concerns, the advancement of biocomposites has resulted in tremendous breakthroughs in green materials in this century. Their primary goal is to replace current synthetic petroleum-based composites with natural resources. Materials derived from nonrenewable petroleum-based sources are hazardous and expensive to produce; on the other hand, biocomposites derived from natural sources are biodegradable, recyclable, non-abrasive, and compostable and have properties comparable to synthetic fiber composites. Natural fibers are low-cost, lightweight, biodegradable, renewable, and environmentally friendly alternatives to synthetic fibers like glass and carbon fiber. The long-term viability of natural fiber-based composite materials has led to increased use in various production industries. However, the manufacturing process of natural fiber-based biocomposites is still plagued by some difficulties, such as poor adhesive propensity, moisture absorption, poor fire resistance, low impact strength, and low durability. This review provides a panoramic view to provide insight into different aspects of biocomposites based on natural fibers and polymers in terms of properties and applications, which will pave the way for future biocomposites research in academic and commercial contexts. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA), one of the well-known bioabsorbable and compostable polyesters has rapidly evolved into a competitive commodity material over the last decades. To provide efficient therapy for the biomedical application domain understanding the PLA properties is the key tenets to achieve suitable chemical and biological properties. In most instances, PLA can be blended or copolymerized with other polymeric or nonpolymeric components. Devices made of PLA and its copolymers tend to slow degradation in vivo without inflammatory reaction and infection. This work intends to give an overview of the characterization and properties of PLA (i.e. crystallization behavior, physical properties, solubility and miscibility, degradation, and thermal properties). Also, we present some information about key elements to enhance PLA and its copolymers/composites/blends properties to optimize their fit with worldwide application requirements. This paper also emphasizes PLA applications in the pharmaceutical and biomedical industries, as well as recent PLA-based biomedical implant developed with Additive manufacturing (AM) devices. [ABSTRACT FROM AUTHOR]

• Tannic acid is neither a good flame retardant nor a highly swelling material. • TA combined with CLS reduces flammability of biocomposite by 30 % compared to PLA. • Mixing of TA with CLS in melt doesn't allow for PHRR reduction of more than 20 %. The purpose of this study was to determine the quantitative and qualitative effects of the form of natural phenolic compounds (NPCs) on the decomposition of polylactide (PLA) under different measurement conditions. For this purpose, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), and pyrolysis-combustion flow calorimetry (PCFC) analyses were carried out not only on individual raw materials like calcium lignosulfonate (BX), tannic acid (TA), BX chemically modified with TA (BMT), but also on PLA/BX, PLA/TA, and PLA/BMT composites with 3, 6, and 9 wt.% of filler. Moreover, the work checked whether to obtain satisfactory results it is necessary to carry out chemical modification lasting many hours, or whether simple physical mixing of ingredients (TABX) is enough, e.g. in proportions 1:2, 2:4, 3:6. The results of these analyses showed that TA is neither a good flame retardant nor a highly swelling material, but when combined with BX physically or chemically, it can produce an interesting synergistic effect. This work proves that chemically obtained BMT hybrid material allows to reduce flammability by 30 % compared to PLA which cannot be achieved by physically mixing these components in a polymer melt. On the other hand, the addition of TABX is sufficient to achieve a good thermal stabilization effect under processing conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Reinforcement with natural fibre has become a common place in a range of industries in the modern day. A polymer matrix can, however, boost the strength of the reinforcing element. When it comes to natural fibres and polymers, they simply do not mix because of their different hydrophobic and hydrophilic properties. However, because the polymer matrix is designed to be hydrophobic, the natural fibres are hydrophilic. This issue can now be rectified with alkalization and a silane binding agent. This technique of modifying natural fibres may result in both rise in surface roughness and a reduction in water attraction and moisture content. In this research, the effects of alkaline and silane treatment were demonstrated using mechanical testing and Fourier transform infrared spectroscopy (FTIR). DSC and TGA tests were used to assess the materials' chemical compositions and thermal properties. In comparison to other composites, those with a 2 percent silane treatment showed improved strength performance. Hemp fibre composites are expected to achieve great performance in industrial applications by enduring chemical treatment. [ABSTRACT FROM AUTHOR]

Suitable packaging material in combination with high-pressure processing (HPP) can retain nutritional and organoleptic qualities besides extending the product's shelf life of food products. However, the selection of appropriate packaging materials suitable for HPP is tremendously important because harsh environments like high pressure and high temperature during the processing can result in deviation in the visual and functional properties of the packaging materials. Traditionally, fossil-based plastic packaging is preferred for the HPP of food products, but these materials are of serious concern to the environment. Therefore, bio-based packaging systems are proposed to be a promising alternative to fossil-based plastic packaging. Some studies have scrutinized the impact of HPP on the functional properties of biopolymer-based packaging materials. This review summarizes the HPP application on biopolymer-based film-forming solutions and pre-formed biopolymer-based films. The impact of HPP on the key packaging properties such as structural, mechanical, thermal, and barrier properties in addition to the migration of additives from the packaging material into food products were systemically analyzed. HPP can be applied either to the film-forming solution or preformed packages. Structural, mechanical, hydrophobic, barrier, and thermal characteristics of the films are enhanced when the film-forming solution is exposed to HPP overcoming the shortcomings of the native biopolymers-based film. Also, biopolymer-based packaging mostly PLA based when exposed to HPP at low temperature showed no significant deviation in packaging properties indicating the suitability of their applications. HPP may induce the migration of packaging additives and thus should be thoroughly studied. Overall, HPP can be one way to enhance the properties of biopolymer-based films and can also be used for packaging food materials intended for HPP. [ABSTRACT FROM AUTHOR]

Depletion of fossil fuels and the detrimental environmental impacts of synthetic plastics have prompted a global interest in bio-based polymers. Lignin is an abundant, unused, and low-value byproduct of pulping and biochemical operations that has the potential to decrease the need for plastics derived from petroleum. Melt blending is one of the easiest strategies for expanding the commercial applications of lignin. Concerns remain, however, regarding the negative effects of lignin on the final composite material's performance, and the increase in manufacturing costs. This study investigates the effects of blending lignin extracted from tobacco using a novel one-step processing technique on injection molding parameters, and the mechanical, physical, and thermal properties of high-density polyethylene (HDPE). By extruding HDPE pellets and lignin powder, varying blend concentrations (0, 5, 10, 15, and 30% wt.) were produced. Scanning electron microscopy (SEM) and optical microscopy were used to investigate the compatibility of the blend morphology. Results indicated that interfacial interactions were achieved as particles of tobacco lignin were well dispersed and uniformly distributed throughout HDPE. Intermolecular interactions between HDPE and lignin were also discovered through Fourier-transform infrared (FTIR) spectral analyses. The tensile test results showed that increase in lignin content up to 15% wt. had little effect on tensile strength, but at 30% wt., a 19% reduction was observed. With the addition of 5, 10, 15, and 30% wt. of lignin, the tensile modulus increased by 4%, 29%, 25%, and 8%, respectively. TGA results demonstrated that at 15% and 30% wt., tobacco lignin acted as a thermal stabilizer. The processability study revealed that tobacco lignin could be processed easily using injection molding without requiring significant changes to the process parameters. Overall, tobacco lignin showed great promise as a biodegradable HDPE filler. [ABSTRACT FROM AUTHOR]

Nanocellulose obtained with acid hydrolysis method using microcrystalline cellulose (MCC) was chemically modified with n-octadecyl isocyanate. Nanocellulose (NC), isocyanate modified nanocellulose (ISO-NC) and MCC were added to poly(ε-caprolactone) (PCL) in order to produce composites by solvent casting method. Transmission electron microscopy (TEM) images showed that diameter of nanofibers ranged from 10 to 20 nm. The surface chemical modification of nanocellulose was characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). In order to understand the effect of cellulose content and modification on the performance of PCL/cellulose composites, surface morphologies, contact angle, thermal and rheological properties of the composites were investigated. The surface chemical modification with n-octadecyl isocyanate improved distribution of NC in PCL matrix. The dynamic mechanical and rheological properties of neat PCL were greatly improved by the addition of ISO-NC with respect to untreated NC and MCC due to the excellent interfacial compatibility between PCL and ISO-NC. [ABSTRACT FROM AUTHOR]

A series of poly(ester amide)s based on dimethyl furan 2,5-dicarboxylate (DMFDC), 1,3-propanediol (PDO), 1,6-hexylene glycol (HDO), and 1,3-diaminopropane (DAP) were synthesized via two-step melt polycondensation. The phase transition temperatures and structure of the polymers were studied by differential scanning calorimetry (DSC). The positron annihilation lifetime spectroscopy (PALS) measurement was carried out to investigate the free volume. In addition, the mechanical properties of two series of poly(ester amide)s were analyzed. The increase in the number of methylene groups in the polymer backbone resulted in a decrease in the values of the transition temperatures. Depending on the number of methylene groups and the content of the poly(propylene furanamide) (PPAF), both semi-crystalline and amorphous copolymers were obtained. The free volume value increased with a greater number of methylene groups in the polymer backbone. Moreover, with a lower number of methylene groups, the value of the Young modulus and stress at break increased. [ABSTRACT FROM AUTHOR]

Nowadays, continuous development of soft-electronics and wearable devices opens to the development needs of stretchable and flexible materials able to interface with the human body. In this scenario, biopolymers are particularly intriguing materials given their biocompatibility and biodegradability. For the application in this specific field the material requires several properties such as biological and mechanical performance and thermal stability. In this study, membranes able to fulfill some of these requirements are described. The electrospun membranes, composed of a blend of polycaprolactone (PCL) and gelatin (GN), have been produced in various configurations. The results show how blend or coaxial systems have different effects on both the interactions between the polymers and their thermal and mechanical properties. An important result of the chosen experimental conditions is the narrow dimensional distribution of the nanofiber diameters constituting the electrospun membranes. Thermal and mechanical tests evidenced that, by properly choosing the material composition and the method of the electrospinning process, membranes capable of withstanding high strain values before the failure can be obtained. In particular, optimizing the electrospinning process and using a blend PCL/GN with a mass ratio of 80/20, it is possible to increase the thermal stability up to 310 °C and confer to the sample the ability to reach a percentage of strain up to 350%. [ABSTRACT FROM AUTHOR]

Fungal biomass (FB), a by-product of the fermentation processes produced in large volumes, is a promising biomaterial that can be incorporated into poly(lactic acid) (PLA) to develop enhanced biocomposites that fully comply with the biobased circular economy concept. The PLA/FB composites, with the addition of triethyl citrate (TEC) as a biobased plasticizer, were fabricated by a microcompounder at 150 °C followed by injection molding. The effects of FB (10 and 20 wt %) and TEC (5, 10, and 15 wt %) contents on the mechanical, thermal and surface properties of the biocomposites were analyzed by several techniques. The PLA/FB/TEC composites showed a rough surface in their fracture section. A progressive decrease in tensile strength and Young's modulus was observed with increasing FB and TEC, while elongation at break and impact strength started to increase. The neat PLA and biocomposite containing 10% FB and 15% TEC exhibited the lowest (3.84%) and highest (224%) elongation at break, respectively. For all blends containing FB, the glass transition, crystallization and melting temperatures were shifted toward lower values compared to the neat PLA. The incorporation of FB to PLA thus offers the possibility to overcome one of the main drawbacks of PLA, which is brittleness. [ABSTRACT FROM AUTHOR]

Lignin is obtained as a by-product in the manufacturing of cellulose pulp for paper. Usually, it is used as internal fuel in this process and, in general, it is not recovered for use as a chemical product. Lignin is the second more abundant natural polymer, and it represents an enormous renewable raw material source. It is well known that epoxy resin is extensively used thanks to its high versatility and its good thermal and mechanical properties. However, most of the commercial epoxy resins use bisphenol A as a precursor, which has been reported to have estrogenic activity. In this work, up to 50 wt% of lignosulfonic acid sodium salt (lignin) has been added to epoxy resin to reduce the amount of both hardener and resin and make a green epoxy adhesive. The effect of lignin on curing kinetics, glass transition temperature and thermal conductivity was explored. The novelty of this work is the use of this green adhesive for cork. It was found that the addition of lignin improves adhesion with cork thanks to the affinity of these materials, and a high percentage of this component produces modifications on the curing process. Besides, with the addition of lignin, the bisphenol A concentration is reduced. [ABSTRACT FROM AUTHOR]

The recent superiority of the composite materials is cautiously focusing on environmental adoption of natural fiber composites. The major source of the natural fiber materials covered in the globe, especially natural fibers, is plant-based, animal-based and mineral-based. Eco friendly based material can save the environment and recycling of the material is possible, as well as important criteria. Hence engineers ultimately focused on natural fiber polymer matrix materials to save the environment, pollution control, plastic manipulation, etc. The literature work was studied to identify natural fiber material possession. The major goal of the present review was to identify material characterization and appropriate application, mainly offering to enhance mechanical properties, flexural strength, electrical properties, thermal properties etc. The major consequence of the natural fiber is hydrophilic treatment. There is poor interfacial adhesion between the addition/filling substances and poor mechanical characteristics. All of these shortcomings constitute a critical issue. This review presents numerous sorts of natural and synthetic polymers, natural fibres such as jute, ramie, banana, pineapple leaf fibre, and kenaf, etc.; short and long fibre loading methods, fibre fillers in micro and nanoparticle, American society of testing and materials (ASTM) standard plate dimensions, fabrication methods such as hand lay-up process, spray lay-up process, vacuumed-bag, continuous pultrusion, and pulforming process, etc.; industries and home appliances such as automotive parts, building construction, sports kits, domestic goods, and electronic devices. The review lists various material combinations, fibre loading, fillers, and matrix that can aid in the improvement of material properties and the reduction of failures during mechanical testing of composites. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the effects of using wood leachate (WL) powder as a cost-effective filler added to novel poly (lactic acid) biocomposites and evaluate their mechanical, thermal, morphological, and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), tensile test, Charpy impact test, Shore hardness, scanning electron microscope (SEM), differential scanning calorimetry (DSC), contact angle, and bacterial growth inhibition tests were employed to characterize the developed biocomposites. The SEM results indicated a proper filler dispersion in the polymer matrix. WL powder improved the hydrophobic nature in the adjusted sample's contact angle experiment. Markedly, the results showed that the addition of WL filler improved the mechanical properties of the fabricated biocomposites. The thermal analysis determined the development in crystallization behavior and a decline in glass transition temperature (Tg) from 60.1 to 49.3 °C in 7% PLA-WL biocomposites. The PLA-WL biocomposites exhibited an antibacterial activity according to the inhibition zone for Escherichia coli bacteria. The developed novel PLA-WL composites can be effectively utilized in various value-added industrial applications as a sustainable and functional biopolymer material. [ABSTRACT FROM AUTHOR]

The development of biodegradable materials as food packaging material is important not only due to the reduction in environmental pollution but also because of an improvement in the functionality. Rice husk-reinforced biopolymers have offered a possible solution to waste-disposal problems associated with traditional petroleum-derived plastics. Rice husk-reinforced low density polyethylene (LDPE)-based biocomposites have been of great interest for their use as food packaging material. In this work, the LDPE/RH biocomposites with different rice husk (RH) content (10, 20, 30, 40 and 50 wt.%) were prepared by the melt mixing process in a laboratory Brabender mixer. The effect of RH content on the physical, thermal and mechanical properties of LDPE was investigated. More importantly, this work aimed to research the biodegradation of the LDPE/RH biocomposites as well as their effect on ‘Granny Smith’ apples’ respiration. The results showed that the incorporation of RH into the LDPE decreased the thermal stability of LDPE, increased water vapour permeability and water absorption, and increased the degree of crystallinity. The incorporation of RH increased the biodegradability of LDPE as well as the postharvest quality of ‘Granny Smith’ apples. The addition of RH in LDPE film significantly decreased fruit respiration and increased firmness as compared to LDPE film. The composting results showed that after the LDPE/RH biocomposite films were biodegraded for 21 days, the biocomposite films with the highest content of rice husks were the most degraded. [ABSTRACT FROM AUTHOR]

There is more demand for natural fiber-reinforced composites in the energy sector, and their impact on the environment is almost zero. Natural fiber has plenty of advantages, such as easy recycling and degrading property, low density, and low price. Natural fiber's thermal properties and flexural properties are less than conventional fiber. This work deals with the changes in the thermal properties and mechanical properties of S-glass reinforced with a sodium hydroxide-treated pineapple leaf (PALF) and banana stem fibers. Banana stem and pineapple leaf fibers (PALF) were used at various volume fractions, i.e., 30%, 40%, and 50%, and various fiber lengths of 20 cm, 30 cm, and 40 cm with S-glass, and their effects on the thermal and mechanical properties were studied, and their optimum values were found. It was evidenced that increasing the fiber volume and fiber length enhanced the flexural and thermal properties up to 40% of the fiber volume, and started to decrease at 50% of the fiber volume. The fiber length provides an affirmative effect on the flexural properties and a pessimistic effect on the thermal properties. The PALF S-glass combination of 40% fiber load and 40 cm fiber length provides maximum flexural strength, flexural modulus, storage modulus, and lowest loss modulus based on hybrid Taguchi grey relational optimization techniques. PALF S-glass hybrid composite has been found to have 7.80%, 3.44%, 1.17% higher flexural strength, flexural modulus, and loss modulus, respectively, and 15.74% lower storage modulus compared to banana S-glass hybrid composite. [ABSTRACT FROM AUTHOR]

New food packaging materials provide an attractive option for the advancement of nanomaterials. The poor thermal, mechanical, chemical, and physical properties of biopolymers and their inherent permeability to gases and vapor have increased this interest. Polymeric materials (matrix) in modern technologies require a filler, which can react/interact with the available matrix to provide a new formulation with improved packaging properties including oxygen permeability, moisture permeability, crystalline structure, barrier properties, morphology, thermal stability, optical properties, anti-microbial characteristics, and mechanical properties. The performance of nanocomposite films and packaging is dependent on the size of the nanofillers used and the uniformity of the nanoparticles (NPs) distribution and dispersion in the matrix. Advancement in nanocomposite technologies is expected to grow with the advent of sustainable, low price, environmentally friendly materials with an enhanced performance. The current review addresses advances in the biopolymeric nanocomposites as alternatives to petroleum plastics in the food packaging industry. It also provides a brief description of biopolymer nanocomposite films and gives general information about different metal NPs with an emphasis on their influence on the emerging characteristics of biodegradable films. The results of recent reports provide a better understanding of the influence of metal NPs in food packaging. [ABSTRACT FROM AUTHOR]

Thermoplastic starch (TPS) is a widely studied biopolymer as an alternative to the use of conventional polymers. In this sense, the incorporation of fillers or reinforcements coming preferably from other substances of natural origin, can be an alternative to try to improve some mechanical and thermal properties of starch polymers. Thus, Kraft Lignin (KL), can be an excellent filler to be incorporated, since it presents mechanical and thermal properties and reduces the cost and weight of the final compounds. TPS films were prepared by casting using dimethyl sulfoxide (DMSO) as solvent and additives with 2, 4 and 8% KL. Characterization of TPS films and compositions with KL were carried out by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), Dynamic Thermomechanical Analysis (DMTA), tensile testing and contact angle. Samples were also analyzed for biodegradation and for the ability to remove contaminants in water, Metil Orange (MO), by Ultraviolet-Visible Spectroscopy (UV–Vis). The FT-IR spectra of the films showed bands typical of functional groups derived from starch and lignin, with the intensity of these bands varying among the samples studied. Micrographs revealed slightly different morphologies among the films, but all showed irregular shapes with structures that appeared as plots. Increasing the percentage of KL led to an increase in contact angle values, showing a more hydrophobic behavior. In the TGA analysis, it was possible to observe a change in the main degradation event of the films for lower temperatures, especially of TPS – 4 and 8% KL compared to the TPS film. Films with KL had the peak of maximum degradation shifted to temperatures below the starch film, where the decrease in intensity of the main peak in the TPS - 4% KL and TPS - 8% KL samples demonstrates that there was less mass loss in the event. There was also in the percentage of residue as the addition of KL was increased The DMTA analyses allowed for the conclusion that presence of KL in TPS film allowed for an increase in its energy storage property, and that the loss modulus followed a decreasing order of storage modulus values to TPS - 8% KL from TPS. For the tensile strength property only TPS - 4% KL has significant improvement, and the elongation at break showed an increase for TPS – 4 and 8% KL compared to TPS. Samples showed a continuous and progressive biodegradation process, being completely biodegraded within 10 days. The monitoring of the ability to remove contaminants from water by UV–Vis, also showed promising results of compounds for this application. The best results were obtained, in most tests, for the TPS- 4% KL films. • Improvement in thermal and mechanical properties in TPS films with KL • The increase in the KL percentage led to a more hydrophobic behavior in TPS films. • Using of KL as a material of added value for improvement of the thermal properties of TPS • The presence of lignin slow down the biodegradation process in TPS films • The KL reduces the mass loss of the TPS film, and can be applied in controlled release. [ABSTRACT FROM AUTHOR]

The utilization of lipids is presently in the spotlight of food industry as they are one of novel renewable and sustainable raw materials. Lipids derived materials are considered as a promising alternate to petro‐based polymers as they are sustainable, biorenewable, biodegradable, and environmentally benign. These unique attributes draw the attention of scientific community for the use of lipids in food packaging applications with a potential to compete with fossil fuel derived polymers. This paper reviews recent advances in the use of lipids and their effect on the barrier, antimicrobial, antioxidant, and mechanical properties of films, coating and nanocomposites for food packaging applications. Modification of lipids and its chemical interactions with other biopolymers during processing for the synthesis of different materials are also discussed. Global patents and research trend in use of lipids for the preparation of biocomposites are also described. The role of lipids in the circular economy is highlighted and life cycle assessment of lipids derived products is outlined with examples. The review is concluded with synoptic view of existing and forthcoming potential use of lipids in various food packaging applications. [ABSTRACT FROM AUTHOR]

Agar/polyacrylamide/quaternary ammonium silane-based (A/P/QAS-based) composite films were developed for food and biomedical packaging applications. The structural, optical, and surface morphological properties of the A/P and A/P/QAS composites were characterized by various characterization techniques in terms of thermogravimetric analysis, differential scanning calorimetry analyses, mechanical and rheological properties. Results showed that the 5% gravimetric loss (57.8–139.1 °C), glass transition temperature (179–189.9 °C) and tensile strength (35.2–47.8 MPa) of the prepared composites increased with increasing polyacrylamide content. The contact angle and water barrier properties of the composites were considerably improved by the addition of QAS. To compare WVP values of the A/P/QAS composite with neat AP composite films it reduced nearly 46% (2.45 to 1.32 × 10−9 g/m2 Pas). The A/P/QAS composites showed excellent antimicrobial properties against five different organisms. The Staphylococcus aureus exhibited highest 25 mm for gel and 18.1 mm for film of A/P/QAS composites. All the composites exhibited shear-thinning behavior, and their viscosity increased with increasing polyacrylamide content. The storage moduli of the prepared hydrogel composites were in the range of 5000–10,600 Pa at 1 rad/s and increased continuously over the entire frequency range. The dynamic rheological properties of A/P and A/P/QAS composites indicated that the prepared composites had good mechanical strength. Biopolymer based A/P and A/P/QAS composite films are suitable for green composite packaging applications. • Novel ternary composites were prepared from agar, polyacrylamide and QAS. • Addition of polyacrylamide improved the rheological properties. • QAS added composites exhibited excellent antimicrobial properties. • Thermal properties and water barrier properties were improved by QAS. • Increasing polyacrylamide content increased the dynamic viscosity [ABSTRACT FROM AUTHOR]