Search

The challenge of dispersing nanocellulose in hydrophobic polymers such as polylactic acid (PLA) still obstacles the further application of cellulose nanocomposites. An environment-friendly and facile wet-shearing pretreatment strategy without using any organic solvent was developed in this work. Silane modified lignocellulose nanofiber (SLCNF) was pre-dispersed into PLA by wet-shearing pretreatment, followed by extrusion process and the SLCNF could be dispersed extremely well in PLA matrices. SLCNF formed a crosslinked network and had an improved compatibility, which improved the mechanical and thermal properties of PLA composites. The tensile strength, elongation at break and thermal deformation temperature of the composites were increased by 12.6 %, 32.4 % and 9.1 °C, respectively. Moreover, SLCNF promoted the crystallization of PLA as a heterogeneous nucleating agent and the crystallinity was increased by about 40 %. This study provides an effective way to disperse nanocellulose in polymer matrix with high efficiency to enhance polymer-based composites. • Wet-shearing pretreatment combined with oven drying is an effective method for dispersing nanocellulose in polymer matrix. • Silane modified reed straw nanofibers formed a cross-linked network and have an improved compatibility with PLA matrix. • Enhanced mechanical, thermal and crystallization properties of polylactic acid/reed straw nanofiber blends [ABSTRACT FROM AUTHOR]

Biocomposites are materials that are easy to manufacture and environmentally friendly. Sugar palm fibre (SPF) is considered to be an emerging reinforcement candidate that could provide improved mechanical stiffness and strength to the biocomposites. Numerous studies have been recently conducted on sugar palm biocomposites to evaluate their physical, mechanical and thermal properties in various conditions. Sugar palm biocomposites are currently limited to the applications of traditional household products despite their good thermal stability as a prospective substitute candidate for synthetic fibres. Thus, thermal analysis methods such as TGA and DTG are functioned to determine the thermal properties of single fibre sugar palm composites (SPCs) in thermoset and thermoplastic matrix as well as hybrid SPCs. The biocomposites showed a remarkable change considering thermal stability by varying the individual fibre compositions and surface treatments and adding fillers and coupling agents. However, literature that summarises the thermal properties of sugar palm biocomposites is unavailable. Particularly, this comprehensive review paper aims to guide all composite engineers, designers, manufacturers and users on the selection of suitable biopolymers for sugar palm biocomposites for thermal applications, such as heat shields and engine components. [ABSTRACT FROM AUTHOR]

Chitosan (C) and zein (Z) were used to develop bilayer films with a characteristic one-way water barrier using a layer-by-layer (LBL) casting method. The effects of mass ratios (C:Z 1:1 , C:Z 1:2 , C:Z 1:3 , C:Z 3:1 , C:Z 2:1) on the microstructure and physicochemical properties of bilayer films were investigated. Bilayer films had uniform microstructures, and C:Z = 1:3 showed a firmer structure as the Z aggregates were distributed in the continuous phase of C. The intermolecular interactions between the C and Z layers were observed using FTIR and XRD analysis. TGA demonstrated that adding Z layer enhanced the thermal stability of C films. LBL coating gave the C/Z bilayer film an increased elongation and tensile strength, as well as a decreased water vapor and oxygen permeability, especially for C:Z = 1:3 which had better properties. The results suggested that C and Z bilayer films may be a promising material for food packaging with the desired water resistance. [Display omitted] • A bilayer film based on chitosan and zein was fabricated by LBL casting method. • Physicochemical property can be tuned by the zein layer. • The bilayer films showed excellent water resistance and mechanical properties. • The C:Z 1:3 films had better mechanical and barrier properties. [ABSTRACT FROM AUTHOR]

Flours and starches extracted from the tropical tubers underwent freeze-drying and cooking in comparison with fresh cooking. Freeze-dried and cooked starch (FDS) granules were found to have different shapes and collapsed arrangement whereas freshly cooked starch (FCS) granules had the least varied structures. The freeze-dried flours had larger structures compared to freshly cooked flours. The physicochemical parameters were high in Dioscorea esculenta (DE)-FDS, followed by Amorphophallus paeoniifolius (AP)-FDS and other samples whereas D. alata (DA)-FCS had the lowest, whereas flours followed similar trend. FDS (42.1%) had the highest solubility index and swelling power whereas FCS (11.1%) showed the lowest. The syneresis and light transmittance levels were higher in FDS and FDF. The freeze dried flour and starch showed higher onset (T 0), peak (T P), and conclusion (T C) temperature than fresh cooked samples. The variations in IR spectra, thermal properties, and crystalline index were termed as differential function of physicochemical characteristics, structural changes that resulted from freeze drying, and cooking treatment employed. • Native tuber starch and flours were characterized based on freezing and cooking. • Physico-chemical data doubled in freeze-dried than fresh-cooked starch and flours. • FTIR revealed deformed starch groups in freeze-dried and cooked flours and starches. • Freezing and cooking changed starch and flour to collapsed, debranched and asymmetrical one. • Thermal analysis supported the effects of deformed starch and flour in freeze-dried samples. [ABSTRACT FROM AUTHOR]

Starch and gluten, the most important macromolecules in wheat flour, vary in thermal properties. The thermal behavior of starch, gluten and their complexes during the manufacture and quality control of flour products need to be accurately understood. However, the high complexity of starch-gluten systems impedes the accurate description of their interactions. When heated within varying temperature ranges and when water molecules are involved, the behaviors of amylose and amylopectin change, and the properties of the starch are modified. Moreover, important indicators of starch granules such as gelatinization temperature, peak viscosity, and so on, which are encapsulated by the gluten matrix, are altered. Meanwhile, the high-temperature environment induces the opening of the intrachain disulfide bonds of gliadin, leading to an increase in the probability of interchain disulfide bond formation in the gluten network system. These behaviors are notable and may provide insights into this complex interaction. In this review, the relationship between the thermal behavior of wheat starch and gluten and the quality of flour products is analyzed. Several methods used to investigate the thermal characteristics of wheat and its flour products are summarized, and some thermal interaction models of starch and gluten are proposed. • The thermal properties of starch and gluten in wheat flour are reviewed separately. • The correlation between the structure and the function of wheat starch and gluten at different temperatures is analyzed. • Factors influencing the interaction between wheat starch and gluten at different temperatures are considered. • Appropriate temperatures are vital in the manufacture of flour products with favorable qualities. • Further utilization of thermal properties is considered in the future. [ABSTRACT FROM AUTHOR]

Renewable yet biodegradable natural fiber (e.g., cellulose nanofiber (CNF)) reinforced bio-based polymers (e.g., polylactic acid (PLA)) are being applied for the manufacture of clean packaging products. The interface incompatibility between hydrophilic CNF and hydrophobic PLA still restricts the promotion of high-performance bio-based products. Herein, a polycondensate-coated CNF hybrid, wherein silane, aluminate, and titanate coupling agent monomers were in-situ polymerized onto the CNF surface via dehydration self-condensation, was designed and further employed as strengthening/toughening nanofillers for fabricating the CNF-reinforced PLA composite. Results showed that the polycondensate coatings could efficiently promote the dispersion of CNFs and enhance interfacial compatibility between CNFs and PLA. Attributing to the synergistic effect of polycondensate coatings and CNFs, a considerable improvement in processing, mechanical and thermal properties was obtained in resultant CNF/PLA composites. With adding 2.5 wt% polycondensate-coated CNFs, the tensile strength, Young's modulus, and tensile toughness of CNF-reinforced PLA composites was raised by about 27 %, 51 % and 68 %, respectively; also, such composite possessed greater elasticity and higher melt strength than pure PLA. This study provides a novel interface control strategy to fabricate low-cost yet high-performance PLA-based composites for sustainable packaging application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In recent decades, research into biomaterials such as silk or cellulose has rapidly expanded due to their abundance, low cost, and tunable morphological as well as physicochemical properties. Cellulose is appealing due to its crystalline and amorphous polymorphs while silk is attractive due to its tunable secondary structure formations which is made up of flexible protein fibers. When these two biomacromolecules are mixed, their properties can be modified by changing their material composition and fabrication methodology, e.g., solvent type, coagulation agent, and temperature. Reduced graphene oxide (rGO) can be used to increase molecular interactions and stabilization of natural polymers. In this study, we sought to determine how small amounts of rGO affect the carbohydrate crystallinity and protein secondary structure formation as well as physicochemical properties and how they affect overall ionic conductivity of cellulose-silk composites. Properties of fabricated silk and cellulose composites with and without rGO were investigated using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, X-Ray Scattering, Differential Scanning Calorimetry, Dielectric Relaxation Spectroscopy, and Thermogravimetric Analysis. Our results show that addition of rGO influenced morphological and thermal properties of cellulose-silk biocomposites, specifically through cellulose crystallinity and silk β-sheet content which further impacted ionic conductivity., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: David Salas-de la Cruz reports financial support was provided by National Science Foundation. Xiao Hu reports financial support was provided by National Science Foundation. This information was provided in the acknowledgment sections., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The biocomposite systems based on mesoporous MCF silica support and protein molecules are characterized with regard to their surface, topographic, thermal properties. Mesoporous silica materials (MCF) covered by the adsorbed protein molecules (BSA and OVA) were examined and characterized by using various techniques including X-ray diffraction, the Fourier transform infrared spectroscopy with attenuated total reflectance, X-ray photoelectron spectroscopy and scanning electron microscopy with microanalysis. The results of study focused on a detailed analysis of microstructure (topography, texture), and chemistry (chemical bonds, functional groups, elemental composition) of protein/mesoporous silica biocomposite. Moreover, the thermal properties of prepared biomaterials were investigated by means of TG/DSC-FTIR-MS-coupled technique. These powerful methods provided detailed information for understanding protein adsorption on MCF. Significant differentiation in surface chemistry and topography of MCF material was observed after protein adsorption. Basing on the results of thermal analysis stronger changes of the surface properties and more stable interactions of biomolecules with MCF-d16 support were observed for larger BSA molecules compared to smaller ovalbumin ones. Unlabelled Image • Microstructure, textural and thermal properties of the protein/mesoporous silica biocomposite are explored • Significant differentiation in surface chemistry and microstructure of MCF material was observed after protein adsorption • More stable biomolecules interactions with MCF support were observed for larger BSA molecules than smaller ovalbumin ones [ABSTRACT FROM AUTHOR]

The physicochemical and thermal properties of whole green banana flour obtained from oven air-drying (ODF) at three temperatures (50, 80 and 110 °C) and freeze-drying (FDF) were compared to wheat flour (WF). Lightness and yellowness were negatively affected by the temperature increment. The FDF samples exhibited higher a* and L* values and had the closest browning index to WF (P-value < 0.01). Also, the ODF50 samples had the highest emulsion activity, whereas FDF had the highest emulsion stability (P-value < 0.05). The oil holding and water holding capacities of the FDF samples were significantly higher than all other samples (P-value < 0.05). A higher resistant starch content was found in the FDF (46.72%) and ODF50 (44.58%) samples. The ODF50 samples had the highest amylose content and degree of crystallinity (P-value < 0.05) as well as the lowest gelatinization temperature amongst the green banana flour samples (4.69 °C). Oven air-drying increased the gelatinization temperature drastically for all GBF samples (P-value < 0.05). In conclusion, drying the whole green banana at 50 °C resulted in the least negative effects on RS content compared to the other drying temperatures investigated in this study and was the closest to the characteristics of the FDF samples. [ABSTRACT FROM AUTHOR]

Abstract Mesona chinensis has been used as a Chinese folk medicine and main ingredient used to make "black bean jelly" in Asia for hundreds of years. In this study, two polysaccharides (MCP-C and MCP-S) from Mesona chinensis were extracted by using cellulase assisted extraction (CAE) and sodium carbonate assisted extraction (SAE), separately. Then the different physicochemical characteristics, rheological and thermal properties of two polysaccharides were analyzed by ion chromatography, high-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), rheological and thermogravimetric analysis. Results indicated that the contents of total sugar and uronic acid of MCP-C were higher than MCP-S, while the protein content and molecular weight was lower than that of MCP-S. MCP-S and MCP-C had differences in the surface morphology by SEM, while they all had the typical IR spectra characteristic and amorphous morphology of polysaccharides. The rheological experiments showed that MCP-C and MCP-S exhibited typical pseudoplasticity fluids behavior. The apparent viscosity (η), storage modulus (G ′) and complex viscosity (η *) of MCP-S were higher than MCP-C. The three-stage decomposition patterns were observed in MCP-C and MCP-S. MCP-S was more stable and had higher initial decomposition temperature (Ti) than MCP-C. Highlights • Two polysaccharides (MCP-C and MCP-S) extracted from Mesona chinensis were studied. • The rheological and thermal stability properties of MCP-C were investigated. • Extraction methods have significant effects on physicochemical and rheological properties of MCP. • MCP-C exhibited lower apparent viscosity and G ′ value than MCP-S. • MCP-C and MCP-S might be a novel natural viscosity modifier in application. [ABSTRACT FROM AUTHOR]

A native polysaccharide (RCPI) with sugar content of 79.94 ± 0.57% was isolated from raspberry fruits. A degraded polysaccharide (DRCPI) with sugar content of 83.82 ± 0.71% was obtained from the crude polysaccharides after degradation by Fe2+-H 2 O 2 treatment. The molecular weights of RCPI and DRCPI were determined to be 411,000 and 8010 Da, respectively. GC analysis revealed that both RCPI and DRCPI were composed of the same monosaccharides (rhamnose, arabinose, xylose, mannose, glucose, galactose, and galacturonic acid) in different molar ratios. IR and NMR spectroscopy confirmed that RCPI and DRCPI possessed similar structural characteristics, although DRCPI displayed higher antioxidant activities and greater thermal stability. Furthermore, DRCPI exhibited excellent rheological properties. These data provide evidence to support the application of raspberry-derived polysaccharides in functional foods. • Two novel polysaccharides (RCPI and DRCPI) from raspberry fruits were obtained. • RCPI (native) and DRCPI (degraded by Fe2+-H 2 O 2) had similar structural characteristics. • DRCPI presented stronger antioxidant and α-amylase inhibitory capacities than RCPI. • DRCPI possessed more excellent viscoelastic behavior and greater thermal stability. [ABSTRACT FROM AUTHOR]

Starch in native form has limited application due to functional and physicochemical characteristics. To overcome these limitations, starch can be modified by non-thermal technologies such as high hydrostatic pressure (HHP). This study investigates high-pressure-induced gelatinization and the effect of this process on the structural, functional, morphological, pasting, thermal, physical and rheological properties of millet starch. The suspension of millet starch and water was pressurized at 200, 400 and 600 MPa for 10, 20 and 30 min to modify the starch in terms of structure, morphology, some physicochemical and rheological properties. Swelling strength and starch solubility decreased as a result of treatment with HHP. All treatments caused to increase in water holding capacity of the starch (from 0.66 % for native starch to 2.19 % for 600 MPa-30 min). Thermal analysis showed a decrease in gelatinization temperature and enthalpy of gelatinization and the pasting properties showed a decrease in the peak viscosity after HHP treatment. In addition, HHP treatment caused to increase in the hydration ability of starch by creating porosity and gaps in the granule surface and increasing the specific surface area. HHP application resulted in an increase in the peak time and pasting temperature and a decrease in breakdown and peak viscosities, final viscosity and setback viscosity in comparison with native starch of millet. The starch sample treated with 600 MPa for 30 min had the lowest syneresis and retrogradation ability. Increasing pressure and the time led to an increase in the elastic nature of the starch samples. According to the results, it is possible to increase usage area of starches in the food industry by improving its technological with HHP. This green physical technology can influence the quality parameters of starch, which can provide benefits for product machining and economic purposes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This paper focuses on the chemical modification of potato starch by the cinnamyl acrylate monomer during the graft copolymerization. The maximum of the grafting percent (G) was found to be 49.2% ± 0.3 at the temperature of 65 °C for 120 min in the presence of 1.0 wt% of potassium persulfate at the starch and monomer ratio 1:2.5. The copolymers exhibited excellent resistance to polar solvents and moisture which was independent of their G values. It was due to the presence of poly(cinnamyl acrylate) chains in their structure and their very compact, non-porous structure. The chemical stability of the copolymers was dependent on the G values. The copolymers showed the highest chemical resistance to neutral and acidic environments rather than to the alkaline one. Their thermal stability was ca. 210 °C under the inert and oxidative conditions. The decomposition mechanism of the copolymers was complex and included a lot of multiple simultaneous processes combined with the emission of various volatiles. The interesting fact was that the pyrolysis of starch from the copolymers occurred before that of the grafted polymer. However, the oxidative decomposition of the grafted polymer began at lower temperatures than that of starch from the copolymers. [ABSTRACT FROM AUTHOR]

Starch from talipot palm trunk (Corypha umbraculifera L.), a new starch source, was treated with different citric acid concentrations (5%, 10%, 20%, and 40% of the dry weight of starch) to produce citrate starch. The influence of citric acid treatment on physicochemical, pasting, structural, thermal, rheological, and digestibility properties of talipot palm starch were studied. A new peak at 1728 cm−1 was observed in the Fourier-transform infrared spectroscopy (FTIR) spectra of citric acid-treated starches, which confirmed the formation of an ester bond between starch molecule and citric acid. The crystalline pattern of talipot palm starch was unaffected by citric acid treatment, whereas the relative crystallinity decreased from 16.35% to 3.06%. The Rapid Visco Analysis of starch treated with citric acid did not show any characteristic peaks, however, the untreated starch showed a peak viscosity of 3646 cP. The gelatinization parameters decreased with an increase in the degree of substitution, and the enthalpy of gelatinization (ΔH gel) decreased from 11.19 J/g to 6.37 J/g. The in-vitro digestibility of talipot palm starch was decreased by citric acid treatment, and that of the slowly digestible starch (SDS) and resistant starches (RS) increased significantly (p ≤ 0.05) from 31.71% to 39.43% and 37.55% to 53.38%, respectively. • The underutilized, non-conventional talipot starch-modified using citric acid • The in-vitro digestibility of starch sample decreased after citric acid treatment. • Storage and loss modulus of talipot palm starch decreased after modification. • The pasting properties were significantly (p ≤ 0.05) decreased. • Relative crystallinity and enthalpy decreased after citric acid treatment. [ABSTRACT FROM AUTHOR]

The need for starch to meet the ever-increasing industrial applications and its inherent problems in the native state have led to researches into unconventional starch sources and starch modifications, respectively. In this study, starch was isolated from African breadfruit kernels and modified to produce acetylated, AC, oxidized, OX, and acid-thinned, AT, starches. The effects of modifications on the native starch, NA, were examined through physicochemical, pasting, morphological and thermal properties. Modifications caused significant (p <.05) reductions in the NA starch moisture, ash, crude protein, crude fat, and crude fibre compositions. Swelling power had direct relationship with increase in temperature. Following modifications, OX starch showed the most significant increase in oil absorption capacity while NA had better water absorption capacity than the modified starches. Acid-thinning significantly improved the gelation and reduced the pasting properties of NA starch. Morphological study using scanning electron micrograph, revealed oblong and oval granules with rough surfaces for all the starches with no significant differences. Thermogravimetry of the starches showed single-step decomposition with increased thermal stability of African breadfruit kernel starch following modifications. DSC study showed that gelatinisation transition temperature of NA reduced following modification. The study showed that modification improved African breadfruit kernel starch properties. • Starch modification significantly reduced kernel starch percent moisture, ash, crude protein, crude fat and crude fibre • Modification did not affect native starch surface morphology and granular shapes • Native starch has a high water absorption capacity and thus can serve as a good thickener • Starch oxidation improved oil absorption capacity of African breadfruit kernel starch • Acid-thinning significantly improved gelation and reduced pasting properties [ABSTRACT FROM AUTHOR]

There are numerous better applications of fibre reinforced polymer composites today, when compared with metals and alloys. Many studies have been conducted to further improve the inherent mechanical and thermal properties of the composite materials, especially with sustainable, environmental friendly, recyclable and biodegradable reinforcements. Consequently, in this current study, the composites were prepared by combining bio solid waste (date seed filler) and vinyl ester to enhance the properties of polymer composites. The date seed filler reinforced vinyl ester (DSF-VE) composites were prepared by using conventional compression moulding technique with varying fillers loadings from 5% to 50%. The mechanical (tensile, flexural, impact and hardness), water absorption and thermal (heat deflection temperature and thermo-gravimetric analysis) properties of the DSF-VE composites were experimentally evaluated. Scanning electron microscopic analysis was carried out to analyse the surface characteristics and fractured surface of the DSF-VE composites. It was evident from the results obtained that 30 wt% of the DSF-VE composites exhibited the highest mechanical properties: impact, tensile, hardness and flexural of 17.03 KJ/m2, 40.3 MPa, 51 and 149 MPa, respectively, among the fabricated composites. Similarly, the heat deflection temperatures of DSF-VE composites increased by 58.49%, when compared with the neat, pure vinyl ester resin. The thermo-gravimetric analysis showed that the natural filler-based (DSF-VE) composites possessed thermal stability up to 400.2 °C, which was within the polymerisation process temperature. Furthermore, the DSF-VE composites have been successfully utilized for various potential applications, such as fabrication of a table fan blade, an engine guard for two-wheelers and self-motor guard for four wheelers. [ABSTRACT FROM AUTHOR]

In this work, we explore the ability of polyhedral oligomeric silsesquioxane (POSS) nanoparticles to increase the compatibility of hydrophilic starch with hydrophobic poly(lactic acid) (PLA) and poly(ɛ-caprolactone) (PCL). Morphological analysis demonstrated that lower contents of POSS (0.5 and 1 wt%) enhances the compatibility of the system. However, higher inclusion of POSS results in the formation of aggregates and thus a lower level of compatibility. Transmission electron microscopy revealed that PCL acts as an intermediate between PLA and starch, and that POSS is primarily localized within the PLA and PCL phases. Based on differential scanning calorimetry, PLA's crystallinity increases from 22.9% to 31.6% upon adding a very low content of POSS (0.5 wt%). However, the PCL's crystallinity is slightly hampered due to formation of these PLA crystallites. In contrast with the crystallization behavior and based on the thermal degradation kinetics, we found the composite's thermal stability is greatly increased when moderate to high contents (3 and 5 wt%) of POSS are utilized. Dynamic mechanical analysis results also confirmed good POSS dispersion within the matrix, especially at lower contents. In conclusion, POSS serves as an efficient compatibilizer for PLA/starch/PCL systems with improved thermal properties. [ABSTRACT FROM AUTHOR]

Jatropha elliptica (Pohl) Muell Arg is a sub-shrub herbaceous plant native to the Brazilian Cerrado, and popularly known as "batata-de-teiú". There is lack of scientific knowledge about the structural characterization, physicochemical and technological aspects of the carbohydrate content present in Jatropha elliptica roots. Thus, this work aim contributes with new data about the evaluation of chemical-structural, thermal and technological properties of starch extracted from "batata-de-teiú". The starch presented low levels of ash, protein and total fiber and amylose content of 32.82%. The initial gelatinization temperature of "batata-de-teiú" starch was 70.1 °C, peak temperature was 73.84 °C and final 85.52 °C, and starch had low trend to retrogradation. The results of x-ray and 13C cpmass show a A-type structure with high crystallinity degree. Finally, this results suggested that the "batata-de-teiú" starch is a macromolecular structure with high branching degree, favoring intermolecular Coulomb, Van der Waals forces and hydrophobic interactions, which directly corroborated with the low solubility observed (maximum of 6.44 g·100 g−1 at 80 °C). The extraction of "batata-de-teiú" starch can be viable, and it has technological characteristics suitable for use in the food industry or pharmaceuticals, since "batata-de-teiú" starch has good thermal stability and low trend to retrogradation. [ABSTRACT FROM AUTHOR]

In the work, the poly(lactic acid) (PLA)/poly (ethylene-butylacrylate-glycidyl methacrylate) (PTW) blends were prepared by melt compounding. PTW as a toughening agent for PLA, the PLA/PTW blends had good compatibility due to the chemical reaction between the epoxy groups of PTW and the end group of PLA during the blending process. With increasing PTW content from 0 to 20%, the impact strength of PLA/PTW blends was enhanced from 4.6 to 54.1 kJ/m2 and the elongation at break was increased from 5.6% to 270%. The scanning electron microscopy (SEM) images of the impact fracture surfaces showed a large amount of cavities and plastic deformation, which caused by the elastomer and the interfacial adhesion enhanced through the interaction of the terminal functional groups. That was the reason that the toughness of PLA was increased. Finally, proteinase K-catalyzed degradation tests shown that the addition of PTW was beneficial to the biodegradation of PLA and reduced environmental pollution. [ABSTRACT FROM AUTHOR]

Bio-composites are easy to manufacture and environmentally friendly, could reduce the overall cost and provide lightweight due to the low density of the natural fibers. In a bid to compete with the synthetic fiber reinforced composites, a single natural fiber composite may not be a good choice to obtain optimal properties. Hence, hybrid composites are produced by adding two or more natural fibers together to obtain improved properties, such as mechanical, physical, thermal, water absorption, acoustic and dynamic, among others. Regarding thermal stability, the composites showed a significant change by varying the individual fiber compositions, fiber surface treatments, addition of fillers and coupling agents. The glass transition temperature and melting point obtained from the thermomechanical analysis and differential scanning calorimetry are not the same values for several hybrid composites, since the volume variation was not always parallel with the enthalpy change. However, the difference between the temperature calculated from the thermomechanical analysis and differential scanning calorimetry was lower. Significantly, this critical reviewed study has a potential of guiding all composite designers, manufacturers and users on right selection of composite materials for thermal applications, such as engine components (covers), heat shields and brake ducts, among others. [ABSTRACT FROM AUTHOR]

In order to diversify the number of applications for poly[( R )-3-hydroxyalkanoates] (PHAs), methods must be developed to alter their physical properties so they are not limited to aliphatic polyesters. Recently we developed Escherichia coli LSBJ as a living biocatalyst with the ability to control the repeating unit composition of PHA polymers, including the ability to incorporate unsaturated repeating units into the PHA polymer at specific ratios. The incorporation of repeating units with terminal alkenes in the side chain of the polymer allowed for the production of random PHA copolymers with defined repeating unit ratios that can be chemically modified for the purpose of tailoring the physical properties of these materials beyond what are available in current PHAs. In this study, unsaturated PHA copolymers were chemically modified via thiol-ene click chemistry to contain an assortment of new functional groups, and the mechanical and thermal properties of these materials were measured. Results showed that cross-linking the copolymer resulted in a unique combination of improved strength and pliability and that the addition of polar functional groups increased the tensile strength, Young's modulus, and hydrophilic profile of the materials. This work demonstrates that unsaturated PHAs can be chemically modified to extend their physical properties to distinguish them from currently available PHA polymers. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of insoluble dietary fiber (IDF) and ferulic acid (FA) on the properties of rice starch (RS), including gelatinization, thermodynamic, rheological parameters, and freeze-thaw stability. Rapid viscosity analysis (RVA), differential scanning calorimetry (DSC), rheological analysis, and freeze-thaw stability analysis were performed. The results showed that the presence of IDF and FA could significantly delay the short-term retrogradation of RS, especially at high FA concentrations. Rheological tests showed that IDF was not conducive for the elasticity, viscosity enhancement, and system stability of the starch gels. However, FA could offset the deterioration of the system caused by IDF and further improve the gel properties. The presence of IDF and FA weakened the freeze-thaw stability of the starch gel, unlike their single action on the starch gel, correspondingly. The results show that FA could alleviate the degradation of RS gel performance caused by IDF in the ternary system. The findings provide potential possibilities for improvements in the quality of rice starch gel-based products., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Abstract Taro starch spherical aggregates have been considered as wall material for the microencapsulation of bioactive compounds. The distribution of particle size, morphology, stability, glass transition temperature, ζ-potential, physical properties and flowability and compression indexes, and functional properties (water, oil and dye retention capacity) were measured. The average diameter was 17.5 ± 0.3 μm. Aggregates formed by a relatively high number of starch granules were observed. The residual protein in the aggregates was in the periphery of the starch granules, favoring the aggregation and the stability under aqueous stirring conditions. The ζ-potential was −21.8 ± 0.3 mV. The value of the glass transition temperature was in the range from 176.8 to 75.4 °C, with 5% and excess water, respectively. The Hausner ratio and Carr index were 1.06 and 14.7, respectively. The oil holding capacity was 1.2 ± 0.01 g of oil·g−1 of dry solid. Overall, the functional, physical and thermal properties of the spherical aggregates of taro starch granules showed that this material offers good potential for the microencapsulation of bioactive compounds. Highlights • Protein acts as a cementing agent in the formation of taro starch spherical aggregates. • The glass transition temperature of spherical aggregates depended positively on the relative humidity. • Spherical aggregates showed low stability in water stringent under stirring. • Spherical aggregates presented higher WRC and ORC than its starch counterpart. [ABSTRACT FROM AUTHOR]