Maximum Degradation Temperature Research Articles

Effect of Alkaline treatment on the characteristics of pineapple leaves fibre and PALF/PP biocomposite

Pineapple leaves fibre (PALF) is one of the natural fibre that has high potential to substitute non-renewable synthetic fibre in thermoplastic products. The PALF were alkali treated with different concentrations of NaOH. Untreated and alkali treated PALF were characterized using Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) to determine the thermal stability and surface morphology of the fibres respectively. Biocomposites were prepared by reinforced alkali treated and untreated PALF with polypropylene (PP) matrix. Tensile properties and water absorption analysis of PALF/PP biocomposites were studied. Biocomposite with 8 wt.% of alkali treated PALF express excellent thermal stability, with maximum degradation temperature at 270 ℃ which is a 7.17% improvement compared to untreated PALF. This biocomposite also had increased tensile strength (116 MPa) with 43% improvement compared to untreated PALF/PP (66 MPa) biocomposite and had lower water absorption at 6% compared to untreated biocomposite which at 21%. Hence, alkali treated PALF is able to improve the characteristic of PALF and increase the compatibility between fibre and polymer by reducing hemicellulose and lignin components.

Green polymer nanocomposites based on natural rubber and nanocellulose whiskers from Acacia caesia: Mechanical, thermal, and diffusion properties

Elastomer composites with biomaterial for high performance have been the recent focus on rubber technology. In the present work, nanocellulose whiskers (NCW) are dispersion in water mixed with natural rubber (NR) latex to fabricate NR-NCW composites. The renewable source of NCW is Acacia Caesia, a medicinal plant with high cellulose content. The morphological analysis shows a homogeneous distribution of NCW in the NR matrix with an average size of 30 nm when the NCW content is 2phr. The addition of 2phr NCW in NR dramatically enhanced tensile strength by 21.5% and modulus by 223% relative to NR gum. The maximum degradation temperature of NR-gum and NR-NCW-2phr is 368 °C and 372 °C, respectively, confirming the composite's thermal stability. The higher crosslink density of NR-NCW-2phr confirmed the superior rubber filler interactions in the NR matrix.

Characterization of alkali-lignin-grafted polyacrylamide synthesized by atom transfer radical polymerization

The preparation of value-added, chemically modified lignin-based copolymers for the use of technical lignin is crucial for green and sustainable development. Herein, we synthesized alkali-lignin-grafted polyacrylamide by atom transfer radical polymerization (ATRP). As alkali lignin (AL) has the highest total hydroxyl group content, it was modified with 2-bromoisobutyryl bromide to synthesize a lignin macroinitiator (lignin-Br) at different ratios of [OH group in AL]:[TEA]:[BiBB] = 1:1:1, 1:1.5:1.5, and 1:2:2. Acrylamide was grafted from lignin-Br with the most Br-initiating sites via ATRP. The ratios of monomer to lignin-Br used were 50:1, 100:1, and 200:1, and the synthesized copolymers (L-g-PAM) were denoted as L-g-PAM50, L-g-PAM100, and L-g-PAM200, respectively. These copolymers were characterized by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (NMR) spectroscopies. The FT-IR and 1H NMR results indicated that polyacrylamide was introduced into the lignin backbone of all L-g-PAM copolymers. Gel permeation chromatography of L-g-PAM showed that the M w of L-g-PAM200 was the highest at 427,383 g/mol. Photographs and scanning electron microscopy images of L-g-PAM showed that L-g-PAM appeared as a soft sponge and contained interwoven fibers. The maximum degradation temperature (T max) of L-g-PAM increased with increasing monomer-to-lignin-Br ratio. Moreover, the glass transition temperature (T g) of L-g-PAM was higher than that of AL. The alkali-lignin-grafted polyacrylamide, synthesized by ATRP, in our study has a narrow molecular weight distribution, and its soft sponge properties make it a hydrogel or another surfactant.

The Influence of Silica Nanoparticles on the Thermal and Mechanical Properties of Crosslinked Hybrid Composites.

This paper presents the synthesis and physicochemical characterization of a new hybrid composite. Its main goals are evaluating the structure and studying the thermal and mechanical properties of the crosslinked polymeric materials based on varying chemical properties of the compounds. As an organic crosslinking monomer, bisphenol A glycerolate diacrylate (BPA.GDA) was used. Trimethoxyvinylsilane (TMVS) and N-vinyl-2-pyrrolidone (NVP) were used as comonomers and active diluents. The inorganic fraction was the silica in the form of nanoparticles (NANOSiO2). The hybrid composites were obtained by the bulk polymerization method using the UV initiator Irqacure 651 with a constant weight ratio of the tetrafunctional monomer BPA.GDA to TMVS or NVP (7:3 wt.%) and different wt.% of silica nanoparticles (0, 1, 3%). The proper course of polymerization was confirmed by the ATR/FTIR spectroscopy and SEM EDAX analysis. In the composites spectra the signals correspond to the C=O groups from NVP at 1672–1675 cm−1, and the vibrations of Si–O–C and Si–O–Si groups at 1053–1100 cm−1 from TMVS and NANOSiO2 are visible. Thermal stabilities of the obtained composites were studied by a differential scanning calorimetry DSC. Compared to NVP the samples with TMVS degraded in one stage (422.6–425.3 °C). The NVP-derived materials decomposed in three stages (three endothermic effects on the DSC curves). The addition of NANOSiO2 increases the temperature of composites maximum degradation insignificantly. Additionally, the Shore D hardness test was carried out with original metrological measurements of changes in diameter after indentation in relation to the type of material. The accuracy analysis of the obtained test results was based on a comparative analysis of graphical curves obtained from experimental tests. The values of the changes course of similarity in the examined factors, represented by those of characteristic coefficients were determined based on the Fréchet’s theory.

Cobalt-doped molecular sieve for efficient degradation of polypropylene into fuel oil: Kinetics and fuel properties of the oil

The present research work is focused on thermogravimetric analysis of polypropylene over cobalt doped molecular sieve (Co/MS). The catalyst reduced the temperature of maximum degradation (Tmax) from 398.2 to 330 °C along with reduction in activation energy. Ozawa Flynn Waal (OFW), Coats Redfern (CR) and Tang Wanjun (TW) methods were applied for calculation of kinetic parameters. The activation energy values were determined in the range of 47.590–54.749, 40.708–60.525 and 41.276–50.283 kJ mol−1 using Ozawa Flynn Waal, Coats Redfern and Tang Wanjun methods respectively, which is relatively less as compared to the E values determined without catalyst using the same models. Furthermore, an effort was made to pyrolyze polypropylene in a salt bath using a glass vessel. The oil and gases recovered were studied through gas chromatography/mass spectrometry. It was concluded that, simple thermal degradation of polypropylene produced no oil; however, thermo-catalytic pyrolysis yielded more than 70% pyrolysis oil having a broad range of components from C4 to C21. Fuel characteristics of the oil determined were found comparable with fossil fuel oil and thus can be used as substitute for energy purpose.

Screening and Identification of a Lignocellulose Degrading Strain and the Condition Optimization

Lignocellulose, the most abundant renewable resource in the world, is not fully utilized due to degradation difficulty. As a result, microbial biodegradation of lignocellulose has become a research hotspot. In this paper, a strain Q7 that degrades lignocellulose efficiently was screened from soil, and identified as Aspergillus niger by morphology and molecular biology. The enzyme-producing conditions were optimized. SEM, FTIR, XRD and TGA of the degraded lignocellulose were performed. The FPA activity of Q7 reached maximum (23.02 U/mL) with 3% straw powder as the carbon source of medium, 1.5% peptone as the nitrogen source, pH = 5, 30 °C. SEM, FTIR, XRD and TGA of the degraded cellulose residue were carried out, which found that the structure of straw was obviously destroyed, the characteristic peaks of some functional groups disappeared, the crystallinity increased, and the decomposition temperature and maximum degradation temperature (Tmax) of the fermented straw increased.

Effect of Eggshell Powder Using for an Extender on the Mechanical and Thermal Behaviors of Polylactic Acid Composites

In this paper, the composites between polylactic acid (PLA) and eggshell powder (ESP) from the chicken shell were prepared by melt blending method in the internal mixer and then injection molded to produce the bio-composite specimen. The effect of the ESP concentration in the composites was investigated on the mechanical and thermal behaviors. The results indicated that the tensile strength and elongation decreased with increased ESP loading. Furthermore, the impact strength was not altered for PLA filled system with 10-30% of ESP. At the 10%wt of ESP in the PLA-composites was not significantly different of the onset (Tonset) and maximum degradation temperature (Td) from neat PLA but at higher ESP loading, Tonset and Td tend to decrease, therefore ESP could be able to accelerate degradation in the composites. The cold crystallization (Tcc) showed decreasing when the ESP was incorporate about 10-30 %wt. Otherwise, the incorporation of ESP affected on the declination of crystallinity in the PLA composites. The morphology, size and elements were examined using a scanning electron microscope (SEM) coupled with an energy dispersive X-ray system (EDX). It was indicated that agglomeration of ESP in the PLA matrix.

New Insights into Segmental Packing, Chain Dynamics and Thermomechanical Performance of Aliphatic Polyurea Composites: Comparison between Silica Oxides and Titanium (III) Oxides

AbstractPolyurea (PU) is intrinsically reinforced by its microphase‐separated morphology, giving its excellent mechanical properties. In this study, it is shown how a high‐index PU formulation applies easy diffusion of hard segments into the soft phase of the PU matrix and tune its chain mobility. Moreover, the interaction of micro (>100 nm), nano (<100 nm) fillers with the microdomains and their thermomechanical properties are unraveled. Herein, nanosilica oxide (NS) and micro titanium (III) oxide (Ti2O3) are incorporated at low loadings into a solvent‐free two‐component aliphatic PU via insitu polymerization. While NS achieves an interfacial interaction with urea groups and forms a tight hard segmental packing, the large‐sized Ti2O3 assembles the interconnected PU chain network, improving its crystallinity. Strong reinforcement by NS is noticed when tensile strength increased from 26 to 31 MPa and on the maximum thermal degradation temperature by 21 °C increment from the neat PU. In contrast, the soft segmental dynamics are triggered with the presence of Ti2O3 as indicated in the reduction in glass transition temperature and the 288% improvement in the storage modulus. This study provides an insightful perspective in designing robust PU composites, effective for myriad applications including strong and flexible films in circuit boards and photovoltaic (PV) cells.

Characterization of natural fiber from manau rattan (Calamus manan) as a potential reinforcement for polymer-based composites

Researches on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications. Herein, in this study, novel cellulosic fibers were extracted from the stem of manau rattan (Calamus manan) by mechanical separation. The chemical, thermal, mechanical and morphological properties of manau rattan fibers were comprehensively analyzed and studied by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), single fiber tensile test and scanning electron microscopy (SEM). Component analysis results showed that the cellulose, hemicellulose and lignin contents of C. manan fibers were 42wt%, 20wt%, and 27wt%, respectively. The surface of the rattan fiber was hydrophilic according to the oxygen/carbon ratio of 0.49. The C. manan has a crystalline index of 48.28%, inducing a maximum degradation temperature of 332.8 °C. This reveals that it can be used as a reinforcement for thermoplastic composites whose operating temperature is below 300 °C. The average tensile strength can reach (273.28 ± 52.88) MPa, which is beneficial to improve the mechanical properties of rattan fiber reinforced composites. The SEM images displayed the rough surface of the fiber, which helped to enhance the interfacial adhesion between the fibers and matrices in composites. These results indicate the great potential of C. manan fibers as the reinforcement in polymer-based composites.

Thermal behaviour of benzoxazine blends based on epoxy and cyanate ester

In the present work, an attempt has been made to develop high-performance polymeric hybrid binary blends of epoxy/benzoxazine and benzoxazine/cyanate ester with varying weight percentages (25/75, 50/50 and 75/25 wt%) of resins, namely, bisphenol-F epoxy resin (DGEBF), benzoxazines [bisphenol–F/aniline (BF-a) and imidazole core-based bisphenol/aniline (IBP-a)] and cyanate ester [bisphenol-F bifunctional cyanate ester (BF-CE)]. The molecular structure, polymerisation temperature/cure behaviour, glass transition temperature (Tg) and thermal stability of the neat polymeric matrices and binary hybrid blends of polymeric matrices were characterised using different analytical techniques, viz. Fourier Transform infra-red spectroscopy (FTIR), Nuclear Magnetic Resonance spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA). Among the binary hybrid blends, the lowest polymerisation temperatures (Tp) were noticed in the case of blends of epoxy/benzoxazine were 219°C for DGEBF/BF-a (25/75 wt%) and 170°C for DGEBF/IBP-a (25/75 wt%). Similarly, in the case of blends of benzoxazine/cyanate ester, the lowest values of Tp observed were 155°C and 153°C for BF-a/BF-CE (75/25 wt%) and IBP-a/BF-CE (75/25 wt%), respectively. The highest values of Tg observed for the blends of epoxy/benzoxazine were 175°C and 254°C for DGEBF/BF-a (25/75 wt%) and DGEBF/IBP-a (25/75 wt%), respectively. Whereas, the highest values of Tg observed in the case of blends of benzoxazine/cyanate ester were 234°C and 278°C for BF-a/BF-CE (25/75 wt%) and IBP-a/BF-CE (75/25 wt%), respectively. From the TGA results of blends, the maximum degradation temperature (Tmax) and limiting oxygen index (LOI) value calculated from the char yield, which ascertain that almost all the binary hybrid blends of epoxy/benzoxazine and benzoxazine/cyanate ester possess good flame retardant behaviour.

Highly thermally stable zirconium oxide deposited layered double hydroxide for enhancing flame retardancy of waterborne epoxy coatings

Inspired by the multifunctional adhesion ability of poly dopamine (PDA), ZrO2 and aluminum magnesium hydroxide (LDH) were combined by PDA, which increased the function of this material in intumescent fire retardant (IFR) coatings. Briefly, PDA was coated on the surface of LDH to improve its dispersion stability in water. Then, the high thermal stability ZrO2 nanoparticles were immobilized in situ on the LDH/PDA surface to improve the strength and temperature resistance of the char layer by a hydrothermal strategy. The fire protection performance of [email protected]@ZrO2 (LPZ) modified intumescent fire retardant (IFR) coatings was performed by large plate method, thermogravimetric analysis (TGA) and furnace experiments. From the results, the IFR coating loaded with 2.5% LPZ exhibited the lowest backside temperature and the highest heat insulation, which reached 177.9 °C and 64.42, respectively. Besides, the coating exhibited the greatest expansion height (23.65 mm) and expansion rate (18.92), which is significantly higher than that of other coatings. Moreover, the maximum thermal degradation temperature (Tmax) and residual char of LPZ2.5%/EP were significantly higher than other samples. Further, the LPZ2.5%/EP based sample indicated the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. The residual carbon analysis showed that ZrO2 nanoparticles and LDH nanosheets remained in the char layer during the combustion process, which is beneficial to increase the strength of the char layer and its barrier effect on heat and oxygen.

Effect of ionic liquids on thermomechanical properties of polyetheretherketone‐multiwalled carbon nanotubes nanocomposites

AbstractPolyetheretherketone (PEEK) nanocomposites with multiwalled carbon nanotubes (MWCNTs) as a nanofiller have emerged as a potential alternative in biomedical applications. However, the effective dispersion of MWCNTs in PEEK matrices is still challenging due to the low compatibility of the MWCNTs with the polymer phase. This article investigates the effect of two ionic liquids (ILs) at different concentrations on thermomechanical properties of PEEK/MWCNTs composites. MWCNTs are modified with various concentrations (0.5–2 wt%) of IL[EMIM]Ac (1‐ethyl‐3‐methylimidazolium acetate) and IL[BMIM]HSO4(1‐butyl‐3‐methylimidazolium hydrogen sulfate), and nanocomposite sheets were prepared by melt‐mixing and thermal pressing methods. Optical and field‐emission scanning electron microscopy micrographs studies confirmed the homogeneous dispersion of IL‐modified MWCNTs in PEEK. Results of nanoindentation and mechanical properties showed the superior mechanical strength of nanocomposites prepared by 1 wt% IL compared to samples prepared without IL. PEEK/MWCNTs nanocomposites containing 1 wt% IL provided 37% higher elastic modulus than that of non‐IL nanocomposites. ILs based PEEK/MWCNTs nanocomposites exhibited maximum degradation temperature. Thermal degradation kinetics of nanocomposites as modelled by the Coats‐Redfern approach indicated the higher activation energy of PEEK/MWCNTs/IL composites. The reported approach for PEEK/MWCNTs nanocomposites fabrication could be potential for promising biomedical applications.

Suitability Evaluation of Mercerized Albizia Julibrissin Fiber as a Potential Reinforcement for Bio-composites

ABSTRACT Natural fibers are currently used as a replacement for synthetic fibers in all possible applications. To enhance the natural fiber’s application suitability, it is necessary to perform alternations on the fiber’s surface using a treatment. The present work deals with the enrichment of various characteristics of Albizia julibrissin fibers extracted from Albizia julibrissin plant stem using mercerization process using 5 (W/V)% of sodium hydroxide solution at four various soaking periods (15, 30, 45, and 60 minutes). The chemical analysis results showed that 45 minutes of the soaking period showed enhanced cellulose content of 60.30%, which was slightly higher than other soaking periods. Thermal analysis showed that char residue was 32% with a maximum degradation temperature of 350.5°C. X-ray diffraction results showed 45 minutes mercerized Albizia julibrissin fibers had a higher crystalline index of 36.36%, while the untreated Albizia julibrissin fibers had 27.77%. Scanning electron microscope elucidated that mercerization process removed the unwanted dirt’s from the surface of Albizia julibrissin fibers; this can aid in better mechanical interlocking with the matrix upon its usage in polymer composites. These desirable things make optimal mercerized Albizia julibrissin fibers as a suitable reinforcement.

Effects of recovered brown alumina filler loading on mechanical, hygrothermal and thermal properties of glass fiber–reinforced epoxy polymer composite

This study investigates the efficiency of recovered brown alumina (RBA) particles filled in epoxy glass-fiber composites. The RBA particles were obtained from grinding wheel rejects with the help of the mechanical crushing process. Recovered particles finer than 120 grit were used as particulate filler for composite preparation. Composites were processed through a hand-layup technique by varying RBA filler loading percentages (0, 5, 10, 15, and 20 wt.%) in a glass fiber–reinforced epoxy matrix. Physical, mechanical, water absorption, and thermal properties of the composites were tested experimentally. By suitable addition of RBA, it is possible to tailor the shore-D hardness, tensile modulus, flexural strength, flexural modulus, and maximum degradation temperature. The 20%-filled RBA composite shows the maximum flexural strength of 382 MPa, and the shore-D hardness value was 85. The fracture surface shows a failure mechanism dominated by matrix cracking and debonding of fiber/particles from the interface. Hygrothermal testing of the RBA20-filled composite reveals 9% and 4% reduction in tensile and flexural properties. The thermal stability of the glass fiber–reinforced composite improves as the filler percentage increases. Maximum thermal stability of 435°C was observed in 20%-filled RBA polymer composite.

Evaluation of the Factors Affecting the Disintegration under a Composting Process of Poly(lactic acid)/Poly(3-hydroxybutyrate) (PLA/PHB) Blends.

The overall migration behavior and the disintegration under composting conditions of films based on plasticized poly(lactic acid)/poly(3-hydroxybutyrate) (PLA-PHB) blends were studied, with the main aim of determining the feasibility of their application as biodegradable food packaging materials. The role of composition in the disintegration process was evaluated by monitoring the changes in physical and thermal properties that originated during the degradation process. PLA and PHB were blended in two weight ratios with 15 wt% of tributyrin, using a Haake mixer and then compression molded into ~150 μm films. We found that the migration level of all of the studied blends was below check intended meaning retained in non-polar simulants, while only plasticized blends could withstand the contact with polar solvents. The disintegration of all of the materials in compost at 58 °C was completed within 42 days; the plasticized PHB underwent the fastest degradation, taking only 14 days. The presence of the TB plasticizer speeded up the degradation process. Different degradation mechanisms were identified for PLA and PHB. To evaluate the annealing effect separately from bacteria degradation, the influence of temperature on materials in the absence of a compost environment was also studied. With the increasing time of degradation in compost, both melting temperature and maximum degradation temperature progressively decreased, while the crystallinity degree increased, indicating that the samples were definitely degrading and that the amorphous regions were preferentially eroded by bacteria.

Quality of Physalis peruviana fruits coated with pectin and pectin reinforced with nanocellulose from P. peruviana calyces

Physalis peruviana is marketed without its calyx, which generates byproducts and a decrease in the shelf life of these fruits. The aim of this study was to evaluate the effect of edible pectin-coatings reinforced with nanocellulose from calyx on the physical-chemical and physiological parameters of P. peruviana fruits during refrigerated storage (5 °C) for ten days. The nanocellulose extraction was carried out using a combined extraction method (chemical procedures and ultrasound radiation). The characterization of the fibers showed that the maximum degradation temperatures ranged between 300 and 311 °C. The SEM analysis revealed the presence of fibers after the chemical treatment. The removal of lignin and hemicellulose was validated using Fourier Transform Infra Red (FTIR) spectroscopy. The results showed that the fruits treated with pectin and pectin reinforced with nanocellulose at 0.5 % (w/w) had an adequate visual appearance and showed a minor color change (ΔE of 19.04 and 21.04, respectively) and the highest retention of L∗ during storage. Although the addition of nanocellulose at 0.5% presented the lowest respiratory rate (29.60 mgCO2/kg h), the treatment with pectin offered the least weight loss and showed the highest firmness retention at the end of storage. Thus, the edible pectin-coating may be useful for improving the postharvest quality and storage life of fresh P. peruviana fruit. Nanocellulose from P. peruviana calyces can be used under the concept of a circular economy; although, its use as a reinforcement of pectin showed some limitations.

The flame retardancy of ionic liquid functionalized graphene oxide in unsaturated polyester resins

SummaryGraphene oxide (GO) was prepared from graphite powder by the classic Hummers method, and modified by 1‐N‐butyl‐3‐methylimidazolium hexafluorophosphate (IL) and 3‐aminopropyltriethoxysilane (KH550) to obtain ionic liquid functionalized graphene oxide (ILGO). ILGO, compounded with traditional flame retardants (ammonium polyphosphate and expandable graphite), was used in unsaturated polyester resin (UPR) to enhance the flame retardancy. The flame retardant property and thermal degradation of the UPR composites were analyzed by limiting oxygen index (LOI), UL‐94, cone calorimeter test (CCT), and thermogravimetric analysis (TGA). The results show that there is an obvious synergism between ILGO and the traditional flame retardants. The LOI value of UPR‐4 containing ILGO reaches 28.2% and passes V‐0 of UL‐94, and UPR‐4's the initial temperature (Ti), maximum degradation temperature (Tmax), and residual carbon greatly increase. The experimental data shows that ILGO can promote UPR to form more residual carbon during combustion, enhance thermal stability, and make the material not easy to decompose. The morphology of carbon layer measured after CCT was observed by scanning electron microscope (SEM). SEM images show that the surface of char layer of UPR‐4 containing ILGO becomes smoother, flatter and denser, compared with UPR containing only flame retardants. The cohesiveness and compact structure residual carbon can effectively prevent the oxygen, combustible gas, and heat transfer between the flame zone and the base material to reduce flammability.

Preparation and characterizations of antibacterial–antioxidant film from soy protein isolate incorporated with mangosteen peel extract

Abstract The mangosteen peel extract (MPE) was used to obtain soy protein isolate (SPI) films. The results show that MPE exhibited a high content of total phenolics and antioxidant activity. Moreover, the MPE can enhance the antibacterial–antioxidant properties, UV-visible light barrier properties, and water-resistant properties of the SPI films. The presence of MPE resulted in an increase in water vapor permeability and hydrophobicity. The extract addition also reduced the film’s crystallinity along with a decrease in the mechanical property and lowering of the maximum degradation temperature. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the polyphenols in MPE could interact with SPI through hydrogen bonds and hydrophobic interactions, and the addition of MPE changed the secondary structure of SPI with a decrease in β-sheets and an increase in β-turns and random coils. Scanning electron microscopy showed that all the films exhibited smooth and homogenous morphology on the surface and on some layers through cross-sectional images. Our results suggested that the MPE would be a promising ingredient to make SPI films used as an active packaging material.

Structural and physico-chemical characterization of industrial hemp hurd: Impacts of chemical pretreatments and mechanical refining

Effective utilization of agricultural and industrial wastes has attracted increasing attention due to the promotion of sustainability and circular economy in our society. In this study, we investigated an economical and environmentally friendly decortication method using metal oxide-assisted hydrogen peroxide oxidization to separate hemp bast and hurd from wasted industrial hemp (Cannabis sativa) stalk. With various chemical pretreatments and mechanical refining, the compositional, structural, and physico-chemical properties of the resulting hemp hurd were comprehensively characterized and analyzed. Chemical composition analysis revealed that decorticated hemp hurd contained 45.66 % cellulose, 24.57 % hemicellulose, and 21.67 % lignin as its major components. The harsher milling conditions led to significantly reduced particle size and destroyed the crystalline structure of hemp hurd bio-aggregates, as indicated by X-ray diffraction and dynamic light scattering results. Chemical pretreatments disintegrated the native cell wall structure, broke covalent or hydrogen-bonded linkages between cell wall components, digested cell wall components, and fractionated hemp hurd into lignocellulosic bio-aggregates with differentiated chemical compositions, morphology, crystalline structure, and thermal stability. Compared to single-step chemical pretreatment, sequential alkaline and bleaching pretreatments removed most of the non-cellulosic components (32.4 wt% reduction) and rendered the resulting hemp hurd fibers with high crystalline structure (70.4 %) and sufficient thermal stability (maximum degradation temperature ∼355 °C). The current study may highlight the importance of chemical pretreatments and particle size for the upscaling of wasted industrial hemp hurd for papermaking, biorefinery, or bioplastic composites industry.

Compressible polyglycolic acid-based nanofibrous matrices as a bone filler: fabrication, physicochemical characterisations, and biocompatibility evaluation

ABSTRACT In this study, amorphous hydroxyapatite (am-HAp) incorporated compressible and nanofibrous polyglycolic acid (PGA-HAp) matrices were fabricated by three-dimensional (3-D) electrospinning. The synthesised am-HAp particles were in the size of 260 ± 45 nm. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses confirmed the chemical and phase structure of the am-HAp particles. Continuous PGA-HAp nanofibers with the mean diameter of 367 ± 70 nm were successfully produced and am-HAp particles were well integrated into the nanofibers. Moreover, XRD and FTIR analyses verified the presence of am-HAp in the PGA nanofibers. The incorporation of the am-HAp to the nanofibers increased the maximum degradation temperature of PGA matrices from 340°C to 362°C. Mechanical analyses confirmed the elasticity of the 3-D PGA matrices. In vitro cell culture studies verified the biocompatibility of the nanofibrous matrices. Hence, 3-D nanofibrous PGA-HAp matrices may be a good alternative to ceramic bone substitutes due to their flexibility and physicochemical properties.