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• Composting rates of polyesters differ strongly depending on the individual studies. • Comparison of composting results and times of polyesters is difficult as no standard conditions are used. • There is no particular standard protocol that give the best composting assessment for polyesters. • This article summarises composting data of representative polyesters using different testing protocol. The aerobic composting of biodegradable plastics can be a promising solution to the growing issue of waste accumulation. Therefore, this article offers a review of papers investigating the biodegradability of polyesters (PLA, PHB, PBS and PCL) in home- and industrial composting. Not only the thermal and biodegradation properties are discussed, but also a comparison is made between the different polyesters under the same composting conditions. From this review, it becomes clear that composting shows promise for polyester waste management. However, although several methods for assessing the composting properties of polyester have been developed, the fact that they rarely follow the same standards does not allow for a comparative analysis that would clearly define composting as the most viable solution. [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]

Recently, starch‐based bioplastics have been proposed to curb the problem caused by conventional plastics. Yet, current bioplastics are made from food sources which cause competition with food industries. Hence, we have produced bioplastics using rotten starch‐based material to tackle this problem. In this study, a comprehensive investigation has been carried out on the preparation of bioplastics extracted from fresh jicama (FJ) and rotten jicama (RJ). Specifically, glycerol as the plasticizer and starch contents were varied to obtain bioplastic with the optimum properties via tensile, chemical and thermal characterizations. The results have confirmed that both FJ and RJ starch bioplastics possessed similar characteristics in terms of physical appearance, transparency and chemical functionalities. Moreover, the tensile and thermal properties of RJ and FJ bioplastics fall within the range specification for packaging applications. FJ bioplastic has maximum stress of 0.43 MPa and maximum strain of 50 MPa at an optimized concentration (St31%_gly6.75) which tells that they formed stronger and higher flexibility than RJ bioplastics. Importantly, the RJ bioplastics have a faster biodegradation rate compared to FJ bioplastics. In conclusion, bioplastics from rotten starch have properties as good as FJ and served as a feasible platform for the development of bioplastics from rotten sources. [ABSTRACT FROM AUTHOR]

In this study, blends of high-density polyethylene/poly(butylene succinate)/high-density polyethylene-grafted maleic anhydride (HDPE/PBS /HDPE-g-MA) blends were prepared by using the injection molding technique. The aftereffect of mixing HDPE-g-MA (as a blend, not as a compatibilizer) and PBS by the different ratios (1, 2, 4 wt%) was investigated by various characterization techniques to give a comprehensive perception of the as-prepared system. The structure was characterized through the FTIR spectra to confirm the existence of PBS and HDPE-g-MA separately in the matrix for each blend that ensures the physical interaction between the components. The mechanical property analysis established that the different ratios of PBS and HDPE-g-MA to the HDPE matrix resembled those of the neat HDPE; however, the elongation at break, the impact strength and hardness of the mixtures were increased by increasing PBS and HDPE-g-MA, respectively. The thermal analysis exposed that the inclusion of PBS caused a decrease in the crystallinity percentage and prompted a decrease in the Melt Flow Index (MFI). The oxidative induction time (OIT) of the neat HDPE had a fluctuating behavior by adding HDPE-g-MA and PBS. The water absorption percentage of the blends was insignificantly increased compared to neat HDPE. The enhanced biodegradation of the blends compared to HDPE could be elucidated by the initiation of microbial deterioration of PBS, inside the HDPE matrix, by the activity of microorganisms that presented in the soil. The mixing of PBS and HDPE-g-MA with HDPE (Fig. a) in different ratios increased the biodegradation of the blends as in Fig. b, c and d. (The pores resulted from degradation are marked in each picture) [ABSTRACT FROM AUTHOR]

Carbon nanotubes are newer generation material broadly emerged for biomedical applications due to its tempting properties such as size and aspect ratio covering surface area to the length, electrical, mechanical and thermal properties in addition to their unique architecture. The view for CNT-based nanomedicines is attractive and promising. Carbon nanotubes compared to other nanocarriers can be easily modified for conjugation of bioactive compounds and ligands for targeting. The applications of carbon nanotubes are not only limited to drug delivery but also in diagnostic applications. Due to a variety of applications in drug delivery, it is necessary to bear in mind the toxicities of carbon nanotubes and catch the way to overcome the problems related to toxicities. Currently, many studies have explored the biodegradation mechanism of carbon nanotubes. Biodegradation shows a conspicuous pathway that enables degradation and removal of CNTs from living body and catalyzes the release of the load from the CNTs. Many articles have been published till date which evidentiary provides the promising applications of CNTs. The present review seeks to provide an overview on intracellular fate, applications and toxicities of CNTs. [ABSTRACT FROM AUTHOR]

Combining polylactic acid (PLA) with waste fibers to produce reinforced biocomposites is of top interest to replace conventional polymers for environmentally friendlier materials. Natural fibers have a remarkable effect on the mechanical and thermal properties of the biocomposites. This reinforcing effect strongly depends on the chemical compositions of fibers, which will also influence the susceptibility of the biocomposites to abiotic and biotic degradation processes. This study evaluated the effect of agave and coir waste fibers over the abiotic and composting degradation of PLA-based biocomposites. Compression-molded PLA/agave and PLA/coir biocomposites using GMA-g-PLA as compatibilizer were subjected to accelerated weathering. Weathered and unweathered samples were further submitted to water absorption to analyze their hydrolytic degradation and composting for biotic degradation. Both fibers showed significant influence on biocomposites degradation. The role of the fibers in UV and hydrolytic degradation was positive for impact properties since the biocomposites were less affected than PLA. Water uptake was increased with fiber addition, while hydrolytic degradation was decreased. The weathering (abiotic degradation) accelerated the PLA biodegradation rate. In general, the results showed that adding both fibers to PLA could help its outdoor performance, maintaining the biodegradable characteristics of these materials. [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]

This study is conducted to evaluate the biodegradation and thermal features of poly(1,4‐cyclohexanedimethylene acetylene dicarboxylate) (PCA) based films and fibers. The PCA is characterized by Fourier transform infrared (FT‐IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopies and gel permeation chromatography (GPC). The beadless fibers of PCA are achieved by electrospinning from its solution under ambient conditions for the first time. The effects of applied voltage and tip‐to‐collector distance (TCD) on the various properties such as morphology, wettability, thermal, and biodegradability behaviors of fibers are investigated by comparing the non‐electrospun PCA. Morphologies and average frequency distributions of the electrospun samples are elucidated by scanning electron microscopy (SEM). Wettability properties of the studied samples are determined by water contact angle (WCA) measurements, whereas thermo‐stabilities and glass transition temperatures (Tg) are established by thermogravimetric and differential scanning calorimetry analyses (TGA and DSC), respectively. Biodegradation studies indicate that 28% of electrospun PCA achieved at 8 mL h−1 flow rate, 20 cm TCD and 25 kV applied voltage can be enzymatically degraded within 15 days. It is thus estimated that PCA with good electrospun and biodegradation abilities will favorable candidates for bio‐polyester applications. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of new fluoro functionalized poly(e-caprolactone)s (F-PCLs) via ring-opening polymerization (ROP) of e-caprolactone (e-CL) for different time intervals (24 and 48 h.) by using 2,2,3,3,4,4,5,5-octafluoro- 1-pentanol (OFP) as an initiator. The structure and properties of F-PCLs are investigated by Fourier-transform infrared (FT-IR), proton and fluorine 19 nuclear magnetic resonance (1H-NMR and 19F-NMR) spectroscopies, gel permeation chromatography (GPC), energy dispersive scanning electron microscopy (SEM-EDS), atomic force microscopy (AFM), water contact angle (WCA) measurements, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Enzymatic degradation experiments are also conducted to study the biodegradation behavior of terminal F-PCLs. Experimental observations obtained by 1H-NMR, 19F-NMR and GPC indicate that higher reaction time leads to the formation of higher fluorinated repeating units in F-PCLs. This observation is confirmed by results of SEM-EDS, AFM, WCA, DSC and TGA analyses, respectively. Based on the biodegradability study of F-PCLs in degradation solutions in the presence and absence of porcine pancreatic lipase, it can observed that utilization of more extended time in the ROP reaction medium decreases the biodegradation of resulting polymer. With the obtained features, biodegradable F-PCLs might have potential applications, particularly in the fields of drug delivery and tissue engineering, requiring improved thermal but lower wettability properties. [ABSTRACT FROM AUTHOR]

In this work, morphological and mechanical properties of biodegradable Polyamide6/Ethyleneoctene Nanoclay/Proteins nanocomposite were studied. The composites were prepared using a laboratory scale twin screw extruder. Morphology of the blend was determined by SEM images. Mechanical properties in term of tensile tests were performed using Testometric TS2000. Stress at break, strain at break and Young's modulus were also determined. The mechanical results demonstrated that the strain at break of the composite decreases sharply by the presence of protein, whereas the Young's modulus increases with increasing protein content. The blend demonstrated the improvement in both mechanical and thermal properties of the final composition. Nowadays, according to the huge application of plastics in different fields, environmental issues were affected by these kinds of non-degradable materials, while the biodegradability of the plastics is just remains an unsolved flaw. In this study, biodegradable blends were prepared using starch as a natural polymer. The outcome of biological procedure-test indicated sufficient weight loss and biodegradation of these blends. [ABSTRACT FROM AUTHOR]

This study is focused on developing and enhancing the properties of durian peel fiber (DPF) reinforced thermoplastic cassava starch (TPCS) composites. The proposed DPF was extracted from agro-waste and incorporated into TPCS with various contents of DPF (10, 20, 30, 40, and 50 wt%) via compression molding. The mechanical and thermal characteristics of the fabricated composites were studied. The thermal properties of the biocomposite were improved with the addition of DPF, as evidenced by an increase in the material's thermal stability and indicated by a higher onset decomposition temperature. The integration of DPF into TPCS improved the biodegradation rate process of the composites. Besides, the results indicated that incorporating DPF in TPCS composites enhanced tensile and flexural properties, with a 40 wt% DPF content exhibited the highest modulus and strength. The tensile and flexural strengths of TPCS/DPF composites were raised significantly from 2.96 to 21.89 MPa and 2.5 to 35.0 MPa, respectively, compared to the control TPCS sample, as DPF increased from 0 to 40 wt%. This finding was consistent with Fourier-Transform Infrared (FT-IR) spectroscopy and scanning electron micrograph (SEM), which showed good interaction between DPF and TPCS matrix. The analysis revealed that DPF at a 40 wt% ratio was the best composition compared to the other ratio. Finally, based on improved results, DPF was identified as a potential resource of green reinforcement for the biodegradable TPCS matrix. [ABSTRACT FROM AUTHOR]

Abstract Based on preliminary research in laboratory, a microbial enhanced oil recovery (MEOR) field trial was carried out in three production wells in Liaohe high pour-point oil reservoir. The three wells are located closely in the same block, share similar geological characteristics. Since all of them held a lower bottom temperature which accounted for serious wax precipitation underground, the microbial agents were injected to remove the waxy blockage for enhancing oil recovery. The results of the pilot showed two of the wells were effective while another well had little effect. In order to identify the functional bacteria and reveal the main mechanism of MEOR in high pour-point oil reservoirs, combined the MEOR field trial, laboratory comparative study on the positive wells and the negative well was carried out. First of all, the microbial communities in the three pilot wells were analyzed by 16S rRNA gene clone library. The results showed the original microorganisms in the two effective wells were highly similar and significantly different from those in the non-effective well. After MEOR treatment, the exogenous surfactant-producing bacteria (ESPB) and the nitrate reducing bacteria (NRB) including Lysinibacillus, Acinetobacter junnii , Sulfurihydrogenibium were abundantly stimulated and shared in the effective wells, which are thought to be the functional microorganisms in this study. Secondly, the oil components were characterized by chromatography and mass spectroscopy, the results indicated resins in the effective well samples were degraded by 5.53%–5.81% after the MEOR treatment, however, the saturated hydrocarbons exhibited little change as well as the oil pour-point. Finally, further comparative analysis for the effluents' physical characteristics demonstrated the bio-emulsification rather than biodegradation played an important role in improving oil mobility and was the main mechanism in this trial. Highlights • There exist significant differences in original microbial communities between effective wells and non-effective wells. • The exogenous surfactant-producing bacteria and the nitrate reducing bacteria are the functional microbes in this trial. • Bio-emulsification plays a more important role than biodegradation in improving oil mobility. • It is essential to analyze the microbial communities and assess the underground environment before MORE field trial. [ABSTRACT FROM AUTHOR]

For this study, waste coal fines were treated with live microalgae slurry at varying biomass ratios to form coal-microalgae blends. The parent samples and the coal-microalgae blends were analysed for their proximate, ultimate and calorific values. Thermogravimetric experiments were performed on the parent samples and coal-microalgae blends under inert conditions. The aim was to investigate the effects of loading live microalgae slurry onto the waste coals with respect to the overall chemical and thermal characteristics of the coal. Based on the analysed results, the blending of microalgae slurry with coal has been shown to enhance thermal decomposition of coal. Coal-microalgae blends have a higher hydrogen content and volatile matter content than coal. Moreover, the presence of microalgae results in faster rates of decomposition at lower temperatures (200-400 °C), and lower residual mass fraction. The blending of microalgae slurries with waste coal appears to be suitable for enhancing the thermal reactivity of waste coal as well as improving the thermal conversion of waste coal. [ABSTRACT FROM AUTHOR]

Recently, the use of biodegradable polymers became the applicable solution to reduce the environmental concerns, which are created by plastic wastes as well as restrictions of petroleum‐based synthetic polymers. By this point of view, polylactic acid (PLA) as a biodegradable and bio‐based polymer is resolving both aforementioned issues. While, the high cost of PLA and its slow biodegradation rate make researchers to blend it with a faster one, for instance, thermoplastic starch (TPS). Adding TPS into PLA can influence on the morphological structure, thermal stability, and biodegradability. In this study, the well‐tuned co‐plasticized TPS via sorbitol/glycerol mixture was melt mixed with PLA for achieving the physically compatibilized PLA/TPS blend. Thermal properties and aerobic biodegradation behavior of samples were discussed in detail considering the morphology development in each blend composition. Thermogravimetric analysis of PLA/TPS blends showed the single degradation peaks, which indicated the fine interdependence between 2 phases. The continuity and content of TPS phase were strongly influenced on moisture absorption and biodegradability of PLA/TPS samples. Also, the presence of TPS accelerated the biodegradation rate of PLA/TPS samples. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Interest for biodegradable polymers is increasing driven by sustainability trend. • Use of CNC as reinforcement in polymer nanocomposites is highlighted. • Effect of CNCs on the overall properties of the nanocomposites is discussed. • Focus on rheological, thermal, mechanical, barrier and biodegradation properties. Abstract Cellulose nanocrystals (CNCs) are considered as one of the most attractive renewable reinforcements for biodegradable polymers due to their promising properties and broad range of applications in several fields. However, the knowledge of CNCs effect on the overall properties of these CNC-based nanocomposites is not fully clarified. This review proposes a comprehensive understanding on the effect of CNCs on the rheological, thermal, mechanical, barrier and biodegradation properties of the main biodegradable polymers. This further understanding is expected to facilitate progress in various sectors of nanotechnology and materials science. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate and optimize the performance of a promising biopolymer, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) which can potentially replace non-biodegradable synthetic polymers derived from toxic petroleum products. Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biofilms were prepared using solvent casting method, and its thermal properties were determined using thermogravimetric and differential scanning calorimetry techniques. Also, the durability and biodegradability of these films were studied by keeping the samples in water and Alabama soil conditions for various lengths of time. Our results showed that the thermal and moisture resistance of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biopolymer can be enhanced significantly with the addition of low halloysite nanotubes concentrations. Also, the biodegradation process of the poly (3-hydroxybutyrate-co-3-hydroxyvalerate) films was faster with the addition of halloysite nanotubes attributed to the accelerated microbial microorganism reaction in the soil. This study led to cognize that the PHBV biopolymers added with halloysite nanotubes can be successfully used for various biomedical, industrial and structural applications, and then decompose at a desired faster rate afterward. [ABSTRACT FROM AUTHOR]

Poly(ester amide)s are attracting attention because they potentially have excellent thermal and mechanical properties as well as biodegradability. In this study, we synthesized a series of novel poly(ester amide)s by introducing γ-aminobutyric acid (GABA) regularly into polyesters, and investigated their properties and biodegradabilities. GABA is the monomer unit of biodegradable polyamide 4 (PA4). The new poly(ester amide)s were synthesized from the reaction of ammonium tosylate derivatives of alkylene bis(γ-aminobutylate) and p-nitrophenyl esters of dicarboxylic acids. All the obtained polymers showed relatively high melting temperatures (Tm). Their thermal decomposition temperatures were improved in comparison with that of PA4 and higher enough than their Tm. The poly(ester amide)s exhibited higher biodegradability in seawater than the corresponding homopolyesters. Their biodegradabilities in activated sludge were also studied.

Soil burial degradation was confirmed to be an efficient waste disposal method for the biodegradable materials with short service life, such as starch/poly (lactic acid) (PLA) composite. The biodegradation behavior about chemical and thermal properties of starch/PLA composite was analyzed by using X-ray photoelectron spectroscopy (XPS), infrared microscopy (IRM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). XPS and IRM results indicated that the biodegradation of PLA occurred at the ester groups in PLA chains. XPS demonstrated the cleavage of C O linkages between glucose rings in starch. DSC and TGA results showed that the starch/PLA composite degraded faster than the pure PLA. During the soil burial degradation, the glass transition temperature of starch/PLA composite exhibited an obviously decrease while it had a slight variation for PLA. The thermal stability of starch/PLA composite shifted towards to that of PLA when they were subjected to soil burial for the same time. It is established that the starch can accelerate the degradation of PLA-based materials, which will enlarge the markets of biodegradable PLA materials used for short service life products. [ABSTRACT FROM AUTHOR]

Chitosan-starch polymers are reinforced with different keratin materials obtained from chicken feather. Keratin materials are treated with sodium hydroxide; the modified surfaces are rougher in comparison with untreated surfaces, observed by Scanning Electron Microscopy. The results obtained by Differential Scanning Calorimetry show an increase in the endothermic peak related to water evaporation of the films from 92 °C (matrix) up to 102-114 °C (reinforced composites). Glass transition temperature increases from 126 °C in the polymer matrix up to 170-200 °C for the composites. Additionally, the storage modulus in the composites is enhanced up to 1614% for the composites with modified ground quill, 2522% for composites with modified long fiber and 3206% for the composites with modified short fiber. The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73% for chitosan-starch matrix up to 16% for the composites with 5 wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiating chitosan-starch films with sustainable features. [ABSTRACT FROM AUTHOR]

In the presented work, the effect of crosslinker geometry on the properties of PVA is reported. The aliphatic (suberic) and aromatic (terephthalic) dicarboxylic acids are used as crosslinker molecules. On the basis of tensile test and thermal properties, it is observed that crosslinking of PVA by suberic acid is more effective than terephthalic acid. The maximum strength measured in crosslinked samples is 32.5 MPa for suberic acid crosslinked PVA which is higher than that of neat PVA (22.6 MPa). Swelling study shows that 8 h crosslinked terephthalic acid (35% w/w) samples have a minimum of 5.4% of water uptake compared to neat PVA, which dissolves readily in water. DTGA shows that the decomposition temperature of crosslinked PVA is 345 °C while neat PVA has a decomposition temperature of 315 °C. FTIR spectroscopy confirms the formation of crosslink ester bond in crosslinked PVA. The crosslinked samples kept for bio-degradation show maximum degradation in terephthalic acid (15% w/w) crosslinked PVA. [ABSTRACT FROM AUTHOR]

ABSTRACT A serials of fully bio-based poly(ethylene dodecanedioate-2,5-furandicarboxylate) (PEDF) were synthesized from Dodecanedioic acid (DDCA), 2,5-Furandicarboxylic acid (2,5-FDCA), and ethylene glycol through a two-step procedure consisted of transesterification and polycondensation. After their chemical structures were confirmed by Nuclear Magnetic Resonance and Fourier Transform Infrared Spectroscopy, their thermal, mechanical, and biodegradation properties were investigated in detail. Results showed that the chemical composition of PEDFs could be easily controlled by the feeding mole ratio of DDCA to FDCA and they possessed the characteristic of random copolyester with the intrinsic viscosity ranged from 0.82 to 1.2 dL/g. With the varied mole ratio of DDCA to FDCA, PEDFs could be changed from semicrystalline thermoplastic to the completely amorphous elastomer, indicated by the elongation at break ranged from 4 for poly(ethylene 2,5-furandicarboxylate) to 1500% for amorphous PEDF-40. The amorphous PEDF-30 and PEDF-40 showed satisfactory shape recovery after cyclic tensile test, which was the typical behavior for elastomer. Enzymatic degradation test indicated that all the PEDFs were biodegradable and the degradation rate was heavily affected by their chemical compositions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46076. [ABSTRACT FROM AUTHOR]

This article focuses on silanisation of reinforcement surfaces to improvise reinforcement-matrix interfaces for developing nettle/PLA biocomposites with enhanced mechanical, thermo-mechanical, and biodegradation properties. Two different silane coupling agents, namely Tri-ethoxy silyl propyl methacrylate (TES-PM) and Amino propyl tri-ethoxy silane (APTES) are taken at different levels of concentration and grafted on the surface of cellulosic nettle reinforcement. The degree of silanisation is measured as an evidence of successful coupling reaction determining the morphological, structural, chemical and mechanical characteristics of the nettle woven reinforcement. It is shown that the interfacial strength of the biocomposite depends on the functional moiety and the level of concentration of the silane coupling agents. It is demonstrated that an appropriate silane coupling agent with an optimal level of concentration brings forth substantial improvement in the static mechanical (tensile, flexural and impact), dynamic mechanical (storage & loss moduli and damping factor) and biodegradation properties of nettle/PLA biocomposite without significant change in the thermal properties. [Display omitted] • Silanisation for the first time on nettle woven reinforcement. • Improved interfaces by altering functional moieties of silane coupling agents. • Augmented interfacial properties with optimal concentration of coupling agents. • Novel green composite from silanised nettle reinforced PLA matrix. • Biocomposite with enhanced physical, mechanical, and thermal properties. [ABSTRACT FROM AUTHOR]

Synthesized via a polycondensation reaction, three biodegradable poly[(butylene succinate)-co-adipate] (PBSA) containing various succinic acid (SA) and adipic acid (AA) ratios were combined with an organically modified layered double hydroxide (m-LDH) to manufacture PBSA/m-LDH nanocomposites. The structures of these PBSA/m-LDH nanocomposites were studied via wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The WAXD and TEM analyses demonstrated that the various nanocomposites formed with exfoliated LDHs were effectively dispensed in the PBSA matrix. The effects of m-LDH on the biodegradation of PBSA/m-LDH nanocomposites were explored using lipase from Pseudomonas fluorescens . The degradation rates of the neat PBSA copolymers decrease in the order PBSA-25 > PBSA-50 > PBSA-75. The faster degradation rate of PBSA-25 is a consequence of the lower melting temperature and flexibility of its chain backbone. Moreover, weight loss decreases with increasing loading of m-LDH, suggesting that the presence of m-LDH hinders the degradation of the PBSA copolymers. On the basis of the molecular weight and polydispersity index of the remaining PBSA-based specimens, we propose that the degradation behavior of PBSA using P. fluorescens lipase is controlled by exo-type hydrolysis activity wherein PBSA copolymer degradation arises from both ends of the polymer chains. [ABSTRACT FROM AUTHOR]

Although the copolymerizations of L-lactide (LA) with seven- or six-membered ring lactones have been extensively studied, the copolymerizations of LA with four-membered ring lactones have scarcely been reported. In this work, we studied the copolymerization of LA with β-propiolactone (PL) and the properties of the obtained copolymers. The copolymerization of LA with PL was carried out using trifluoromethanesulfonic acid as a catalyst and methanol as an initiator to produce poly(LA-co-PL) with Mn of ~50,000 and PL-content of 6-67 mol %. The Tg values of the copolymers were rapidly lowered with increasing PL-contents. The Tm and ∆Hm of the copolymers gradually decreased with increasing PL-contents, indicating their decreased crystallinity. Biodegradation test of the copolymers in compost demonstrated their improved biodegradability in comparison with the homopolymer of LA. [ABSTRACT FROM AUTHOR]

Purpose: Biodegradable polymers are currently gaining importance in several fields, because they allow mitigation of the impact on the environment related to disposal of traditional, nonbiodegradable polymers, as well as reducing the utilization of oil-based sources (when they also come from renewable resources). Fibers made of biodegradable polymers are of particular interest, though, it is not easy to obtain polymer fibers with suitable mechanical properties and to tailor these to the specific application. The main ways to tailor the mechanical properties of a given biodegradable polymer fiber are based on crystallinity and orientation control. However, crystallinity can only marginally be modified during processing, while orientation can be controlled, either during hot drawing or cold stretching. In this paper, a systematic investigation of the influence of cold stretching on the mechanical and thermomechanical properties of fibers prepared from different biodegradable polymer systems was carried out. Methods: Rheological and thermal characterization helped in interpreting the orientation mechanisms, also on the basis of the molecular structure of the polymer systems. Results and conclusions: It was found that cold drawing strongly improved the elastic modulus, tensile strength and thermomechanical resistance of the fibers, in comparison with hot-spun fibers. The elastic modulus showed higher increment rates in the biodegradable systems upon increasing the draw ratio. [ABSTRACT FROM AUTHOR]

The objective of this work is to investigate the loss of performance undergone by a polymer during a long-term closed-loop recycling process. High density polyethylene (HDPE) is subjected up to 50 extrusion cycles under constant processing conditions. The effect of recycling is then determined by following its degradation with increasing number of generation. After selected cycles, the material is characterized in terms of physical (density, GPC), thermal (DSC, TGA), and mechanical (tension, flexion) properties. No significant change are observed in density, DSC, and TGA tests. But for GPC, the weight average molecular weight (Mw) is found to decrease while the number average molecular weight (Mn) do not change significantly, thus leading to a decreasing polydispersity index. Intrinsic viscosity also decreases, while melt flow index (MFI) increases. From the tensile stress-strain curves, recycling seems to have no significant effect on Young's modulus (Ey), but a moderate increase of the strain at yield is observed followed by a slight decrease, while the stress at yield decreases. For the break-up conditions, stress and energy at break are found to increase significantly. Finally, three-point bending tests show that the flexural modulus (Eb) decreases with recycling. Overall, the recycling process leads to an important modification of the polymer's mechanical properties mainly due to chain scission. [ABSTRACT FROM AUTHOR]

Poly(ethylene brassylate) (PEB) is a biodegradable polyester that nowadays is of particular interest owing to its poly(ε-caprolactone)-like properties (with a T g at −30 °C and a T m at 70 °C) and the low-cost of its monomer. However, it is not simple to achieve high molar masses with conventional catalysts. In this work, high molar mass PEBs, characterized by SEC-MALS, were successfully synthesized using triphenyl bismuth (Ph 3 Bi) as catalyst. Then, with the aim of evaluating the impact of the molecular weight on the physical properties, several PEBs ranging from 27 to 247 kg mol −1 were prepared. It was demonstrated that above a M w of 90 Kg mol −1 , PEB behaved in a constant manner. PEBs with lower molecular weight (<46 Kg mol −1 ) showed lower values of T g (~(−35 °C)) and presented a melting peak that was split into three or four different peaks while their crystallites started to melt earlier (at ~30 °C). In addition, these PEBs were more sensitive to thermal degradation (two additional stages of degradation were observed) and, what is more important, were found to be prone to brittle fracture. As the M w rose, the PEB samples became more ductile and those PEBs with a molecular weight above 90 Kg mol −1 possessed deformation at break values higher than 800%, secant modulus in the 296–324 range and ultimate tensile strength of >20 MPa. [ABSTRACT FROM AUTHOR]

Cellulose derivatives, such as cellulose acetate (CA), are commonly used due to their ease of processing. These polymers present interesting mechanical properties and biodegradability, but low thermal stability under melt processing conditions. Composites of carbon nanotubes (CNTs) and cellulose derivatives are expected to present enhanced properties, depending on the effect of nanotubes on polymer structure and thermal properties. This work aims to investigate the influence of melt mixing on the stability of CA and its CNT composites. Composites with 0 wt%, 0.1 wt% and 0.5 wt% CNTs, as received and functionalized with pyrrolidine groups, were prepared using a batch mixer and an extruder. Chain scission of CA occurred during processing, but the effect was considerably reduced in the presence of CNTs. The incorporation of small amounts of CNTs (with or without functionalization) decreased polymer degradation by thermomechanical effects induced during polymer processing. [ABSTRACT FROM AUTHOR]

• Successful synthesis of aliphatic aromatic co-polyesters with C6-C16 even carbon long chain dicarboxylic acid as monomer. • Effects of aliphatic segment length and content on different properties. • The unique crystallization behavior is caused by sufficient chain length and aliphatic content. • Biodegradation mechanism of aliphatic aromatic co-polyesters with long chain dicarboxylic acid as monomer. • The introduction of long enough aliphatic segments has a positive effect on biodegradation. In this work, dimethyl terephthalate (DMT), 1,4-butanediol (BDO) and different diacids were introduced to investigate the effects of variations in aliphatic chain length and component content in aliphatic aromatic terpolymers on the basic thermal properties, crystalline morphology, mechanical properties and biodegradability of the polyesters. The experimental results from nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR) and Gel permeation chromatography (GPC) indicate the successful synthesis of the anticipated aliphatic aromatic co-polyesters. The variation of melting and crystallization temperatures with aliphatic chain segment length and content were analyzed by differential scanning calorimetry (DSC). The Wide-angle X-ray diffraction (WAXD) results suggest that the coexistence of both crystals formed by rigid and flexible chain segments can be achieved by varying the length and component content of the aliphatic chain segments in the co-polyesters. The scanning electron microscopy (SEM) and composting experiment results indicate that the type of crystals formed with the more flexible chain segments and the lower degree of crystallinity have a positive effect on the biodegradability. [ABSTRACT FROM AUTHOR]

Films of PBAT/TPS (poly(butylene adipate- co-terephthalate)/thermoplastic starch) (starch plasticized with glycerol containing citric and stearic acids) without and with 0.6 wt% starch nanoparticles were produced by extrusion. The presence of nanoparticles during the extrusion process led to a higher degree of starch gelatinization improving starch compatibility with PBAT. Nanoparticles modified the interaction between the different components of the PBAT/TPS composite. The hydroxyl groups of the starch nanoparticles interacted with starch amylose by means of hydrogen bonds. In addition, nanoparticles modified the structure of the PBAT rigid segment (BT): a shift of Tm of BT toward lower temperatures and a slight shift of the relaxation of the BT segment to higher temperatures were observed. The incorporation of nanoparticles also had a reinforcing effect on the PBAT/TPS matrix. The composite presented slight increases of Young's modulus ( E) and stress at break ( σb) without affecting the strain at break ( ϵb). The rate of biodegradability was improved with the use of starch nanoparticles. The composite showed faster deterioration than the matrix, showing the first changes in its tonality and breakdowns at only 6 days of burial in compost. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this study, we want to investigate the effects of fibers content and surface modification ofSpartium junceum (SJ) fibers on the water absorption characteristics, thermal degradation, and morphological properties of SJ-reinforced poly (vinyl chloride) (PVC) composites. In addition, the change in mechanical proprieties of the composites after biodegradation test was evaluated by tensile strength. In order to improve the interfacial interactions between the PVC matrix and the SJ fibers, SJ fibers were modified by sodium hydroxide (NaOH), vinyltrimethoxysilane (VTMS) and treated with sodium hydroxide solution followed by VTMS (NaOH+VTMS). The results show that the water uptake of PVC/SJ fibers composites increases with the increase in the fibers’ content. However, the surface modification reduces water uptake. Moreover, the results indicate that the kinetics of water absorption of the PVC/SJ fibers composites approaches the Fickian diffusion mechanism. Also, the results indicate that the tensile strength of the composites is affected by the biodegradation test and chemical treatments. The atomic force microscope pictures of the composites illustrate the reduction of roughness via surface treatments of fibers. [ABSTRACT FROM PUBLISHER]

Poly(lactic acid) (PLA) is a well-known biodegradable polymer with strong potential application in food packaging industry. In this paper, samples of PLA clamshell for tomatoes packaging were exposed with 60 CO γ-ray's source (1.33 MeV) at different dose levels (0, 10, 60, 150, 300, and 600 kGy), at room temperature and in presence of air. The physicochemical properties of neat PLA and sample exposed to gamma irradiation were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile measurements. Results show as the dose increases, the molecular weight ( M w ), melting temperature ( T m ), tensile strength and elongation at break decreased. However, the tensile modulus increased with increasing doses. The surface of PLA clamshells was degraded (scratches and minor cracks) when samples were exposed to doses greater than 60 kGy. [ABSTRACT FROM AUTHOR]

Bamboo, among other natural plants, has a special structure, with different characterization along the culms and between species. In this study, the thermal stabilities of four bamboo species, named Dendrocalamus pendulus (DP), Dendrocalamus asper (DA), Gigantochloa levis (GL), and Gigantochloa scortechinii (GS), were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under a nitrogen atmosphere. Each species was divided into three different portions: bottom, middle, and top, and fibres were manually extracted from the specified sections of each species. The thermal analysis of extracted bamboo fibres indicated that the thermal degradation behaviour of each bamboo species varied from bottom to top and between species. However, these variations were lower in DA species compared to GS, GL, and DP, because of minor differences between lignocellulosic components of its three portions. The top and middle portions of the four species degraded at a higher temperature range (314 to 379℃) than the bottom portions. The results of this study suggest that DA and GS species, according to their thermal stabilities, are most suitable for use as reinforcement in composite materials. [ABSTRACT FROM AUTHOR]

ABSTRACT Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis using a 1 : 3 molar ratio of PET repeating unit to glycols like neopentyl glycol (NPG) and dipropylene glycol (DPG). Further, a series of waterborne polyurethanes (WPUs) was synthesized using pure polypropylene glycol (PPG), and glycolyzed oligoesters/PPG blends in different molar ratios as soft segment. Thermal property of WPU was tested by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Moreover, viscosity and particle size of WPU were also investigated. The results show that introduction of a certain amount of glycolyzed oligoester to soft segment makes the degree of hard-soft domain microphase separation smaller, and can also improve thermal stability of WPU. Furthermore, WPUs synthesised from glycolyzed oligoesters and PPG blends possess larger particle size, better particle size distribution, relative lower and more stable viscosity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42757. [ABSTRACT FROM AUTHOR]

Biodegradable poly(butylene succinate) (PBS)/basalt fiber (BF) composites were prepared by melt blending method using twin-screw extruder followed by injection molding. Mechanical properties, crystallization and melting behavior, morphology, crystal structure and thermal stability of PBS/BF composites with various BF contents were investigated by different techniques. The tensile and impact properties of the composites were improved markedly with the addition of BF, due to the efficient interfacial adhesion between fibers and PBS matrix. Crystallization and melting behavior of PBS in its composites kept almost unchanged, indicating that the nucleation effect of BF was minimal and, meanwhile, it played a role in hindrance of chain motion. TG analysis showed that the thermal stability of PBS/BF composites was enhanced by the addition of BF. The crystal structure of PBS was not affected by the incorporation of BF, while the nucleation density increased gradually and the spherulite size reduced remarkably with the increase in BF. No transcrystallization phenomenon on the surface of BF was observed maybe as a result of without surface treatment. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, poly(1,4-butylene adipate) (PBA)/organomodified layered double hydroxide (m-LDH) nanocomposites were synthesized and characterized as a new material for green materials use. m-LDH was initially prepared with magnesium nitrate hexahydrate, aluminum nitrate-9-hydrate, oleic acid, and sorbitol by a novel one-step coprecipitation method to intercalate the oleic acid and sorbitol organomodifier into the interlayer of the layered double hydroxide. The solution mixing process was then applied and shown to be an efficient method for fabricating the PBA/m-LDH nanocomposites. The m-LDH characterized by X-ray diffraction (XRD) showed a high interlayer spacing of 58.8 Å. The morphology and thermal properties of the PBA/m-LDH nanocomposites were characterized with XRD, transmission electron microscopy, and thermogravimetric analysis. It was shown that the m-LDH was well distributed in the PBA matrix and that the thermal properties of the PBA/m-LDH nanocomposites significantly improved with a loading of 0.1 wt % m-LDH. Finally, the biodegradability of the PBA/m-LDH nanocomposites was tested with lipase from Pseudomonas fluorescens as a microbial catalyst. It was shown that an addition of m-LDH up to 0.5% resulted in a significant difference in terms of the biodegradability. After 120 h of degradation, the residual weight and surface morphology of the composite films were affected by the presence of m-LDH. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42083. [ABSTRACT FROM AUTHOR]

The present study aimed at exploiting the unfavorable changes of thermally modified shellac with the idea of developing starch/shellac-based composites intended for food contact applications. On baking shellac samples at 200°C for different time intervals (0–20 min), functional groups and linkages were drastically modified, especially anhydride formation, polyesterification, and ether/acetyl linkage occurrences. These processes caused a marked increase in the glass transition temperatures (from about 33 to 60°C) and melting temperatures (from 175 to about 230°C) but a decreased solubility in ethanol (from 95 to 9%). The addition of shellac into a starch-based formulation for producing shaped bodies in combination with heat could significantly strengthen the composite materials and drastically reduce the water uptake after soaking in both cold water and hot water. Furthermore, application of a food-grade biodegradable coating showed remarkable improvement in terms of water resistance and mechanical strength of the composites. The first attempt at making chopsticks was successful and showed promising results. Nevertheless, forming processes and mold designs of such articles—long narrow tubes—need further study. [ABSTRACT FROM PUBLISHER]

ABSTRACT The biodegradation of poly(vinyl alcohol) and poly(vinyl alcohol)-graft-lactic acid copolymers was analyzed, using Trichotecium roseum fungus. The samples were examined during biodegradation at different periods of exposure. Structural modifications of the biodegraded samples were investigated by Fourier transform infrared-attenuated total reflectance spectroscopy, and the surface morphology was investigated by scanning electron microscopy. The static light scattering results concluded that the weight average molecular mass ( Mw) of the copolymers increased after biodegradation, because the fractions with low molecular weight of the copolymers were destroyed. The thermal behavior and stability of the samples before and after the biodegradation period were investigated by differential scanning calorimetry (DSC) and thermogravimetric analyses. The thermogravimetric analyses and their derivatives (TG-DTG) showed that the thermal stability of the biodegraded samples was more raised comparatively to the unbiodegraded ones. The DSC results demonstrated that biodegradation took place in the amorphous domains of the investigated polymer samples and the crystallinity degree increased after 24 biodegradation days. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41777. [ABSTRACT FROM AUTHOR]

ABSTRACT Because of high susceptibility to thermal degradation during conventional melt processing of poly(3-hydroxybutyrate) (P3HB) homopolymer, incorporation of a second or third monomer unit in the polyester backbones is expected to reduce the melting temperature and crystallinity, resulting in a controlled thermal degradation with improved stability. In this work, random poly(3-hydroxybutyrate- co-3-hydroxyvalerate- co-4-hydroxyvalerate) (P3HB3HV4HV) terpolyesters biologically synthesized by Cupriavidus necator were investigated for the thermal stability and degradation over a broad temperature range (100-300°C) in comparison with P3HB homopolyester. The work revealed that below the complete melting point (around 150°C), the terpolyester exhibited a high thermal stability and became an amorphous semisolid suitable for conventional thermal processing. Size exclusion chromatography plus nuclear magnetic resonance analysis was used to examine the thermal degradation products and the vulnerability of different monomer units at high temperatures (240-290°C). We found that 3HV unit in P3HB3HV4HV copolymers was more vulnerable to thermal degradation than 3HB unit under air. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41715. [ABSTRACT FROM AUTHOR]

Little is known about the thermal properties and internal molecular structure of transitory starch. In this study, granule morphology, thermal properties, and the cluster structure of Arabidopsis leaf starch at beginning and end of the light period were explored. The structural properties of building blocks and clusters were evaluated by using diverse chromatographic techniques. On the granular level, starch from end of day had larger granule size, thinner crystalline lamellae thickness, lower free surface energy of crystals, and lower tendency to retrograde than that from end of night. On the molecular level, the starch had lower amylose content, larger cluster size, and higher number of blocks per cluster at the end of day than at end of night. It is concluded that the core of the granules contains a more permanent molecular and less-ordered physical structure different from the transitory layers laid down around the core at daytime. [ABSTRACT FROM AUTHOR]

The thermal dehydration and degradation of chitosan and citralidene chitosan was studied by differential scanning calorimetry at four different heating rates; 5, 10, 15 and 20 K min. The kinetics of thermal dehydration and degradation of chitosan and citralidene chitosan was investigated using different isoconversional and maximum rate (peak) methods viz. Kissinger-Akahira-Sunose (KAS), Tang, Starink, Starink, Flynn-Wall-Ozawa (FWO) and Bosewell. The activation energy values of thermal dehydration and degradation reactions obtained from isoconversional methods of FWO and Bosewell are slightly higher than that obtained from other methods. The variation of activation energy, E with conversion function, α, established using these different methods were found to be similar. Compared to the FWO method, the KAS method offers a significant improvement in the accuracy of the E values. All the maximum rate (peak) methods yielded consistent values of E for the dehydration and degradation reactions of both chitosan and CIT-chitosan [ABSTRACT FROM AUTHOR]

ABSTRACT Bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and alkaline lignin composites were prepared via melt processing method, and the influence of amorphous lignin on the crystallization behavior and thermal properties of PHBV were investigated. It was found that dual melting peaks appeared in DSC curves of PHBV/lignin composites, while only one single peak existed in PHBV. The non-isothermal crystallization process analyzed by Jeziorny method suggested that lignin changed the nucleation mode of composites and hindered the crystallization rate of PHBV. Data calculated from the results of WAXD demonstrated that lignin did not change the basic crystal structure of PHBV, but decreased the average size of the lamellar stacks. POM results confirmed that the effect of lignin on the crystallization behavior of PHBV carried out in two opposite way, namely the enhanced effect of nucleation and the hindered effect of growth. Besides, the thermal stability of composites was also decreased significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41325. [ABSTRACT FROM AUTHOR]