Thermal Degradation Temperature Research Articles

Bacterial cellulose production through the valorization of waste apple pulp and stale bread

AbstractIn this work, stale bread and waste apple pulp were used as feedstocks for the production of bacterial cellulose (BC). A glucose-rich solution was prepared from stale bread by dilute acid hydrolysis, while an extract comprising fructose and glucose was obtained from the waste apple pulp, which was used for cultivating Komagataeibacter xylinus DSM 2004, either as sole feedstocks or supplemented with Hestrin-Schramm medium. Supplementation significantly improved BC production: 3.38 ± 0.09 g/L for waste apple pulp extract and 2.07 ± 0.22 g/L for stale bread hydrolysate. There was no significant impact on BC chemical structure or fiber diameter, but the biopolymer produced from waste apple pulp extract had slightly higher crystallinity (CI = 59–69%) and lower thermal degradation temperature (Tdeg = 341–350 ℃) than that of the stale bread hydrolysate (CI = 55%; Tdeg = 316–320 ℃). Moreover, supplementation of the waste apple pulp extract led to the preparation of thicker membranes, with higher Young’s modulus, tension, and deformation at break but lower water uptake capacity and lower permeability to O2 and CO2. These results show that waste apple pulp and stale bread are suitable feedstocks for BC production and the cultivation conditions can be adjusted for tailoring the biopolymer’s mechanical and barrier properties to suit different applications.

Bio-Based Self-Healing Epoxy Vitrimers with Dynamic Imine and Disulfide Bonds Derived from Vanillin, Cystamine, and Dimer Diamine.

The condensation reactions of 4,4'-(ethane-1,2-diylbis (oxy)) bis(3-methoxybenzaldehyde) (VV) with cystamine, 1,6-hexamenthylene diamine, and a dimer diamine (PriamineTM 1075) produced three types of vanillin-derived imine-and disulfide-containing diamines (VC, VH, and VD, respectively). Thermal curing reactions of polyglycerol polyglycidyl ether with VD and mixtures of VC/VD and VH/VD produced bio-based epoxy vitrimers (BEV-VD, BEV-VC/VD, and BEV-VH/VD, respectively). The degree of swelling and gel fraction tests revealed the formation of a network structure, and the crosslinking density increased with a decreasing VD fraction. The glass transition temperature, tensile strength, and tensile modulus of the cured films increased as the VD fraction decreased. In contrast, the thermal degradation temperature of the cured films increased as the VD fraction increased. All the cured films were healed by hot pressing at 120 °C for 2 h under 1 MPa at least three times. The healing efficiencies, based on tensile strength after the first healing treatment, were 75-78%, which gradually decreased as the healing cycle was repeated. When imine-and disulfide-containing BEV-VC/VD and imine-containing BEV-VH/VD with the same VC/VD and VH/VD ratios were used, the former exhibited a slightly higher healing efficiency.

Characterization of Novel Cellulosic Salvadora Persica Fiber for Potentiality in Polymer Matrix Composites

ABSTRACT Natural fiber is expected to make polymer composites light and environmentally friendly. In this paper Salvadora persica natural fiber is characterized in view of its use in composite materials for the first time. Average diameter of the fiber was 250 µm and density was 1.3 g/cm3. The surface of the fiber was irregular with impurities and surface features such as shallow tubs, cell walls and lignin were revealed by Scanning Electron Microscopy (SEM). X-ray diffraction (XRD) analysis reveals Crystallinity Index (C.I) of 58% and Crystallite Size of 3.58 nm. The chemical bonds pertaining to different constituents of the natural fiber such as cellulose, hemicellulose and lignin were identified by Fourier Transform Infrared (FTIR) spectroscopic analysis. In the thermal degradation of the fiber during the Thermogravimetric analysis (TGA), three stages were identified. The maximum thermal degradation temperature (Tfinal) was determined to be 357°C. Tensile strength, Young’s modulus and percentage elongation of the fiber were 430 ± 100 MPa, 16 ± 3.9 GPa and 4.2 ± 0.91% respectively.

3D printing novel enteric capsule shells for personalized drug delivery

Individualized drug delivery presents a viable strategy for enhancing medication efficacy and patient safety. It involves producing small batches of custom dosages tailored to each patient’s individual needs. However, current pharmaceutical manufacturing processes are not designed for personalized dosage forms. Additive manufacturing processes have great potential in the pharmaceutical industry due to the customizable nature of 3D printing technologies and the increasing demand for customized pharmaceutics and drug delivery systems. Conventional enteric capsules are prepared by dip coating to achieve gastro-resistant release, but the manufacturing process is erratic and unreliable. This study aimed to investigate the feasibility of manufacturing enteric capsules from enteric polymers using the hot melt extrusion (HME) and fused filament fabrication (FFF) process. HME was utilized to prepare filaments using enteric polymers, Hypromellose acetate succinate (HPMC-AS), and Eudragit-L 100–55, with plasticizers, sorbitol, and polyethylene glycol 4000 (PEG-4000), and a thermoplastic polymer, polyvinyl alcohol (PVA). A computer-aided design program was utilized to design size 0 capsules. The prepared capsule design and filaments were used to fabricate capsules using the FFF process. Powdered red dye was used to simulate the drug and its release from FFF fabricated capsules was evaluated in simulated gastric and intestinal fluids, pH 1.2 and 6.8, respectively. Various combinations of enteric polymer, plasticizer, and thermoplastic polymer were examined. Thermogravimetric analysis (TGA) showed that the temperatures used for processing polymer blends were well below their thermal degradation temperatures, and dye release profiles were generated using image analysis software. This study demonstrates that capsules made with HPMCAS, PEG-4000, and PVA via the FFF process are suitable for controlling drug release and that the release profile can be modified by making small changes to the formulation.

Chemical analysis and performance evaluation of ClearCorrect® aligners as received and after intraoral use: Implications for durability, aesthetics, and patient safety

BackgroundOrthodontic treatment with transparent aligners is popular with patients. Any alteration of the plastic material, as subjected to the oral environment, could influence the treatment's durability, the aligner's aesthetic appearance, and the patient's safety. PurposeThis study concerns the physicochemical properties of ClearCorrect® aligners before and after intraoral use, focusing on transparency, surface topography, leachable, polymer glass transition temperature, and viscoelastic properties. MethodsAligners were collected after two weeks of intraoral use. Unused samples were obtained from the manufacturers. Transparency was measured by UV–visible spectroscopy. Chemical modifications were studied using infrared and Raman spectroscopies. Thermal degradation, glass transition (Tg), and storage modulus (E') were characterized by thermal analysis (DSC, TGA, DMA). Surface morphology and roughness were studied thanks to SEM and AFM. Aligners were immersed in water-based solutions to identify and quantify organic leachable by HPLC chromatography and trace elements by atomic absorption spectroscopy. ResultsClearCorrect® aligners have a three-layer structure (outer PETG/inner PU layers). Slight chemical alterations occurred after aging. There was also no significant evolution in Tg and thermal degradation temperatures and only a minimal evolution of E'. Surface and transparency alterations occurred. A difference in organic compound and trace element release levels between new and used aligners was evidenced, suggesting an intraoral release during use. SignificanceIntra-oral aging mainly impacts the aligner transparency and surface. The leachable study suggests significant ingestion of organic and non-organic compounds by the patient: investigations are needed to assess the impact of the long-term use of trays on patient health.

Epoxidized cardanol oleate (ECD-OA) as an effective biobased chain extender of polylactic acid (PLA)

Moisture exposure during polyester processing can lead to degradation, resulting in the formation of carboxyl and hydroxyl end-groups. To preserve mechanical properties, thorough drying and the use of chain extenders like epoxy acrylates and isocyanates during extrusion are crucial for maintaining or enhancing molecular weight through in-situ reactions. Our study introduced epoxidized cardanol oleate (ECD-OA), containing epoxy and long-chain alkyl groups, as a potential chain extender, and compared its effectiveness with commercially available epoxidized cardanol glycidyl ether (cardolite NC514). Compared to neat PLA without chain extension, the addition of 1 phr ECD-OA resulted in an increase in the molecular weight (Mw) of PLA from 15.3 × 104 g/mol to 17.1 × 104 g/mol, demonstrating a chain extension efficiency of 11.8 %. The melt flow rate of PLA decreased from 9.9 g/10 min to 5.0 g/10 min, and the initial thermal degradation temperature of PLA increased by 5.7 °C. Upon chain extension, there was a substantial increase in both the elongation at break and tear resistance of the PLA film. The results demonstrate that ECD-OA can extend PLA molecular chains through chemical reactions and promote entanglement with the long alkane chain, consequently enhancing the mechanical and thermal properties of PLA. Due to the enzyme's preference for biobased small molecules, the PLA film with the addition of a biobased chain extender is more prone to enzymatic degradation compared to neat PLA. To conclude, ECD-OA acts as a bio-based chain extender that improves the performance of PLA while also enhancing its biodegradability.

Physical, mechanical and thermal properties of novel bamboo/kenaf fiber-reinforced polylactic acid (PLA) hybrid composites

This study investigates the physical, mechanical, and thermal properties of bamboo (BF) and kenaf (KF) fiber-reinforced polylactic acid (PLA) hybrid composites. Three hybrid (30BF-70KF, 50BF-50KF, and 70BF-30KF) and two non-hybrid (BF-PLA and KF-PLA) composites were developed through twin screw extrusion and compression molding techniques. The physical properties (density, void content, crystallinity via XRD, and chemical interactions via FTIR), mechanical properties (tensile, flexural, compressive, impact, and hardness), and thermal properties (Thermogravimetric analysis-TGA and Differential scanning calorimetry-DSC) were thoroughly analyzed. BF reinforcement reduced the composites’ density to 1.1826 g/cm³, while the inclusion of KF increased it to 1.2479 g/cm³. 50:50 blend of bamboo-kenaf reinforcement achieved the lowest void content of 0.27 %. The XRD patterns revealed heightened crystallinity in the BF-PLA composite. FTIR analysis showed stable functional groups, with O–H absorption bands indicative of cellulosic fibers. The BF-PLA non-hybrid composite exhibited the highest tensile strength at 25.95 MPa and compressive strength at 173.15 MPa, with the 30BF-70KF hybrid composite showing notable impact strength. Fractured morphology by FESEM revealed superior fiber-matrix adhesion for BF-PLA composite. TGA demonstrated a variation in thermal degradation temperatures, with the BF30-KF70 composite showing the highest onset of degradation at 484 °C. DSC analysis indicated a reduction in the glass transition temperature (Tg) across all fiber-reinforced samples and revealed significant adjustments in melting and crystallization temperatures. This research highlights the potential of BF-KF/PLA hybrid composites in the development of eco-friendly plastic furniture and consumer products.

Unveiling the impact of nitrocellulose-enveloped nCuO on the thermal characteristics of ammonium nitrate-based solid composite propellants utilizing polyurethane/nitrocellulose blend binders

ABSTRACT This study investigates the combined effects of coated nano copper oxide (NC@nCuO) and polyurethane (PU) modification on the thermal degradation kinetics and combustion properties of ammonium nitrate-based solid composite propellant. Nitrocellulose (NC) is used as a coating for nCuO, forming a core-shell structure, and as a binder in a PU/NC blend. Surface modification of ammonium nitrate was achieved through repeated spray coating. The formulations underwent thorough thermal characterization using thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses. TG analysis showed a significant decrease in thermal degradation temperature due to AN modification with NC@nCuO and the use of PU/NC as a binder. Isoconversional kinetic methods (it-KAS, it-FWO, and VYA/CE) based on DSC tests were used to predict kinetic parameters, revealing a substantial impact of NC-coated nCuO and PU modification on the reactivity of the propellant, reducing the activation energy from 125 kJ/mol (reference) to 99 kJ/mol (nCuO) and 94 kJ/mol (NC@nCuO). Additionally, combustion tests were conducted. The results showed that the introduction of nCuO reduces the ignition delay by 5.25 ms and the combustion duration by 0.06 ms, while NC@nCuO further reduces these by 8.17 ms and 0.12 ms, respectively. Additionally, there is a 23% and 65% increase in flame intensity relative to the reference formulation after the incorporation of nCuO and NC@nCuO, repectively.

Preparation, characterization and thermal properties of the PS+Si based polymer nanocomposites

Polymer nanocomposites based on polystyrene and polycrystalline Si nanoparticles have been successfully synthesized using the solution-casting method. The scanning electron microscope and x-ray diffraction methods show that the Si nanoparticle size in the obtained nanocomposite was up to 50 nm. The thermostability of the obtained nanocomposite was studied depending on the concentration of Si nanoparticles in the PS matrix. It was found that Si nanoparticles that are distributed homogeneously in the polymer matrix act as a thermal barrier. By adding 3% Si nanoparticles into polystyrene polymer, the thermal degradation temperature of PS increases by 20°, and the decomposition rate reduces from −42,460 mg/min to −35,099 mg/min. In addition, it was shown that Si nanoparticles do not affect the PS glass transition temperature, which explains that the porous Si does not reduce the free volume for the polymer molecules to move. The polymer macromolecules just are adsorbed on the porous silicon surface, which partially limits their mobility.

Constitutive Model for Thermal-Oxygen-Aged EPDM Rubber Based on the Arrhenius Law.

Ethylene-propylene-diene monomer (EPDM) is a key engineering material; its mechanical characterization is important for the safe use of the material. In this paper, the coupled effects of thermal degradation temperature and time on the tensile mechanical behavior of EPDM rubber were investigated. The tensile stress-strain curves of the aged and unaged EPDM rubber show strong nonlinearity, demonstrating especially rapid stiffening as the strain increases under small deformation. The popular Mooney-Rivlin and Ogden (N = 3) models were chosen to fit the test data, and the results indicate that neither of the classical models can accurately describe the tensile mechanical behavior of this rubber. Six hyperelastic constitutive models, which are excellent for rubber with highly nonlinearity, were employed, and their abilities to reproduce the stress-strain curve of the unaged EPDM were assessed. Finally, the Davis-De-Thomas model was found to be an appropriate hyperelastic model for EPDM rubber. A Dakin-type kinetic relationship was employed to describe the relationships between the model parameters and aging temperature and time, and, combined with the Arrhenius law, a thermal aging constitutive model for EPDM rubber was established. The ability of the proposed model was checked by independent testing data. In the moderate strain range of 200%, the errors remained below 10%. The maximum errors of the prediction results at 85 °C for 4 days and 100 °C for 2 and 4 days were computed to be 17.06%, 17.51% and 19.77%, respectively. This work develops a theoretical approach to predicting the mechanical behavior of rubber material that has suffered thermal aging; this approach is helpful in determining the safe long-term use of the material.

Thermal, mechanical, and morphological properties of oil palm cellulose nanofibril reinforced green epoxy nanocomposites

In this study, significant improvements in mechanical properties have been seen through the efficient inclusion of Oil Palm Cellulose Nanofibrils (CNF) as nano-fillers into green polymer matrices produced from biomass with a 28 % carbon content. The goal of the research was to make green epoxy nanocomposites utilizing solution blending process with acetone as the solvent with the different CNF loadings (0.1, 0.25, and 0.5 wt%). An ultrasonic bath was used in conjunction with mechanical stirring to guarantee that CNF was effectively dispersed throughout the green epoxy. The resultant nanocomposites underwent thorough evaluation, comparing them to unfilled green epoxy and evaluating their morphological, mechanical, and thermal behavior using a variety of instruments. Field-emission scanning electron microscopy (FE-SEM) was used to validate findings, which showed that the CNF were dispersed optimally inside the nanocomposites. The thermal degradation temperature (Td) of the nanocomposites showed a marginal decrement of 0.8 % in temperatures (from 348 °C to 345 °C), between unfilled green epoxy (neat) and 0.1 wt% of CNF loading. The mechanical test results, which showed a 13.3 % improvement in hardness and a 6.45 % rise in tensile strength when compared to unfilled green epoxy, were in line with previously published research. Overall, the outcomes showed that green nanocomposites have significantly improved in performance.

Nanoencapsulation of phase change material with CuO nanoparticles: Development of thermal properties for energy storage

Today, the efficient use of energy resources has become essential due to the increasing need for energy. Therefore, thermal energy storage systems are used to minimize lost energy and more efficient energy consumption can be achieved by preventing energy losses. Phase change materials (PCMs) can be effectively used in thermal energy storage and are among the promising materials for a carbon–neutral future. In this study, the synthesis of nanoencapsulated phase change material (NEPCM) containing CuO NPs for use in thermal energy storage systems is included. In the production of phase change material, Copper oxide Nanoparticles were added into urea–formaldehyde resin as shell material, and an NEPCM, a eutectic mixture of capric acid-myristic acid, was prepared. Since the final product will be used in the structure, the phase change material was optimized for room temperature. In-situ polymerization, the synthesis process was carried out to obtain a better shell material to improve thermal properties and prevent leakage. Scanning Electron Microscopy and Fourier-transform infrared spectroscopy analysis were used to determine the morphology and chemical structure of the prepared NEPCM. Elemental analysis was performed to determine the presence of CuO NPs as shell material in urea–formaldehyde resin. Differential scanning calorimetry analyses were performed to determine the thermophysical properties. While the thermal degradation for CuO NPs-NEPCM occurred between 22.78–29.45 °C, the thermal degradation temperature shifted and the thermal degradation status in the first stage was less than that of normal NEPCM. It was observed that the thermal stability and strength of NEPCM increased with the addition of CuO NPs. NEPCM containing CuO NPs has thermal energy storage and energy conservation potential in buildings as a heat storage material. This study can provide an effective way to synthesize form-stable CuO-doped NEPCMs that are economically feasible for thermal applications and have the potential to contribute to future energy storage requirements.

Fabrication and characterization of rippled graphene/LDPE composites with enhanced hydrogen barrier properties

Hydrogen plays a pivotal role as a sustainable energy carrier, but the cost-effective and efficient production of gas barrier materials for hydrogen storage still poses a considerable challenge. In this research, we investigate the hydrogen barrier properties of nanocomposites based on low-density polyethylene (LDPE) filled with varying concentrations (0–5 wt%) of rippled graphene. The low-density polyethylene rippled graphene (LPRG) nanocomposites were prepared by drop-casting a suspension of graphene with LDPE dissolved in Toluene, which resulted in a uniform dispersion of rippled graphene within the LDPE matrix. Mechanical testing revealed notable improvements in tensile strength (+40%) and Young's modulus (+120%), confirming the reinforcing effect of rippled graphene in the polymer matrix. Results from the thermogravimetric analysis showed that the addition of rippled graphene significantly increased the thermal stability of the material, reporting an increase of 77 °C in the thermal degradation temperature at a nanofiller loading of 1 wt%. Additionally, the incorporation of rippled graphene in the composite improved the thermal conductivity by 161 %. Moreover, it resulted in an electrically percolated network at a critical nanofiller loading of 1 wt%, contributing to enhanced electrostatic discharge safety. Finally, gas permeability tests unveiled a 50% reduction in hydrogen permeability of LPRG with graphene content of 5 wt% compared to pristine LDPE, making graphene/LDPE composites a superior choice for sustainable and efficient hydrogen storage applications.

Enhancing Mechanical Properties of PLA Filaments through Orange Peel Powder Reinforcement: Optimization of 3D Printing Parameters

This study investigates the augmentation of the mechanical properties of Polylactic Acid (PLA) filaments by incorporating Orange Peel Powder (OPP) as an eco-friendly filler for 3D printing applications. The study delves into optimizing the printing parameters to achieve enhanced mechanical characteristics while maintaining printability. Various 3D printing process parameters were analyzed systematically to assess their impact on tensile strength, flexural strength, and impact resistance. A thorough investigation was conducted to determine the impact of layer height, infill density, and printing speed on the overall mechanical properties of the printed specimens. The findings demonstrate that adding 25% OPP significantly enhances the mechanical strength of the PLA composite without compromising printability, with optimal concentration and printing parameters identified. Thermo gravimetric study reveals that the PLA/OPP composite filament has a higher maximum thermal degradation temperature of 329 °C, compared to the PLA’s temperature of 316 °C. This research contributes to advancing the development of sustainable and mechanically robust materials for additive manufacturing, offering insights into the fabrication of PLA-based biodegradable composites tailored for specific applications in various industries.

Properties of foam concrete containing phase change material impregnated pumice

Energy consumption rises as a result of numerous electrical devices used to maintain thermal comfort of interior building areas. Using building materials with low thermal conductivity and density as well as an effective thermal energy storage plan can help to mitigate this. In order to enhance thermal performance of building, phase change material (PCM) was incorporated to foam concrete mixture in this study. Capric acid (CA)-palmitic acid (PA) eutectic mixture was prepared and impregnated with pumice (50 % by weight), a light and porous material. DSC results indicated that pumice/CA-PA composite exhibited a melting temperature of 22.84˚C and a freezing temperature of 20.85˚C, with corresponding enthalpy values for melting and freezing determined to be 85.4 J/g and 85.1 J/g, respectively. TGA analyses demonstrated that operational temperature of pumice/CA-PA composite was significantly below its thermal degradation temperature (194˚C). The prepared pumice/CA-PA composites were replaced with silica aggregate at different rates and incorporated in foam concrete mixture. Porosity and water absorption values rose as pumice/PCM content increased, yet there was a 7.2–41.1 % drop in dry unit weight when compared to reference. Compressive strength also showed a linear decrease and the lowest compressive strength value was recorded as 4.71 MPa in the presence of 40 % pumice/PCM. Thermal conductivity dropped from 0.487 W/mK to 0.167 W/mK, suggesting that foam concrete samples that were produced are all suitable as insulation materials. In peak solar radiation hours, PCM-impregnated pumice foam concrete (PFC) provided about 11.8 % and 8.72 % surface and room center temperatures compared to that of the reference in maximum case. PFC with PCM provided 6.54 % warmer surface temperature in cold weather. PFC-PCM can provide a cooler indoor temperature during peak temperature hours. Therefore, it may have a great potential to decrease the cooling load of a building.

Fabrication of transparent glass fabric‐reinforced thermoplastic composite based on tow‐spreading technique

AbstractHighly transparent and mechanically robust thermoplastic composites have been developed by hot‐pressing PETG with E‐glass fabrics. The tow‐spreading technique facilitates the reduction of internal defects and fiber crimp angle in the composites, thereby significantly improving their optical and mechanical properties. The optimized composite containing 55.1 vol% glass fibers and 0.4 mm thickness has a high transmittance of 86.1%@616 nm and a low overall haze of 7.2%. Moreover, the 1 mm thick composites exhibit tensile strength of up to 340 MPa and impact strength of up to 86.3 kJ/m2. After 28 days of hygrothermal or UV aging, the composites show minimal changes in their glass transition temperature and thermal degradation temperature. The chemical structure also remains unchanged, with no observed crystallization. In comparison to UV aging, the composites demonstrate better resistance against hygrothermal aging. Specifically, the hygrothermal aged sample displayed a light transmittance retention rate of 93.5% and a bending strength retention rate of 94.3%, while these values were reduced to 73.3% and 90.5%, respectively, in the UV aged sample. The opto‐mechanical properties enhanced mechanism and aging degradation mechanism have been identified by microscopic morphological observation. This work provides an innovative and straightforward approach to fabricate transparent, recyclable, high‐strength thermoplastic composites.Highlights Highly transparent, mechanically robust, recyclable glass‐fabric reinforced thermoplastic composites are fabricated. Composites with spread‐tow fabrics exhibits improved transparency. The fabrication route is scalable and cost‐effective. The mechanism for opto‐mechanical properties enhancement are proposed.

Semi-Interpenetrating Polymer Network Anion Exchange Membranes Based on Quaternized Polybenzoxazine and Poly(Vinyl Alcohol-Co-Ethylene) for Acid Recovery by Diffusion Dialysis.

Acid recovery from acidic waste is a pressing issue in current times. Chemical methods for recovery are not economically feasible and require significant energy input to save the environment. This study reported a semi-interpenetrating polymer network (semi-IPN) anion exchange membranes (AEMs) for acid recovery by diffusion dialysis with excellent dimensional stability, high oxidation stability, good acid dialysis coefficient (UH +) and high separation factor (S). Semi-IPN AEMs are prepared by ring-open cross-linked quaternized polybenzoxazine (AQBZ) with poly(vinyl alcohol-co-ethylene), where AQBZ is obtained by Mannich reaction and Menshutkin reaction. All four proportions of semi-IPNs exhibit clear micro-phase separation, which is conducive to ion transport. The water uptake (WU) of the four semi-IPNs ranges from 14.2 % to 19.2 %, while the swelling ratio (SR) remains between 8.7 % and 11.3 %. These results indicate that the cross-linked structure in the designed semi-IPNs effectively control swelling and ensure dimensional stability. The thermal degradation temperature (Td5) of semi-IPN4:6 to semi-IPN7:3 varies from 309 °C to 289 °C, with an oxidation stability weight loss rate (WOX) ranging from 91.5 % to 93.5 %, demonstrating excellent thermal stability and oxidation stability. The semi-IPNs also show good UH + values ranging from 11.9-16.3*10-3 m/h and high S values between 38.6 and 45.9, indicating the promising potential of the semi-IPNs.

Ultrasound and enzyme treatments on morphology, structures, and adsorption properties of cassava starch

Porous starch materials are environmentally friendly and renewable and exhibit high adsorption performances. Ultrasound and compound enzyme (α-amylase and glucoamylase) treatments were applied to prepare modified cassava starch. The granules, crystal morphology, crystal structure, and molecular structure of starch were investigated. The hydrolysis degree, solubility, swelling, and adsorption properties of cassava starch were analyzed. After the cassava starch was modified by ultrasound and enzyme treatments, the granule size of the starch decreased, and the surfaces were eroded to form pits, grooves and cavity structure. The starch spherulites weakened or even disappeared. The functional groups of starch did not change significantly, but the degree of crystal order decreased. The double-helix structure was reduced, and the crystal structure was composed of A + V-type crystals, with a decrease in crystallinity. The gelatinization temperature and thermal degradation temperatures enhanced. The enzymatic hydrolysis degree and solubility of the modified cassava starch increased. The swelling degree decreased, and oil adsorption, water adsorption improved. MB adsorption behavior of modified cassava starch closely followed a pseudo-second-order kinetics model and the Langmuir isotherm equation. These findings could help to understand the relationship between the structure and properties of modified starch, and guide its application in the field of adsorption.

Thermal Degradation and Chemical Analysis of Flame-Retardant-Treated Jute Fabrics.

Jute is an inherent lignocellulosic fiber, consisting of hemicellulose, α-cellulose, and lignin. Industrial ventilation, automotive composites, upholstery, carpets, military uniforms, hospital furnishings, and curtains necessitate the integration of flame-retardance properties into jute fibers. In this investigation, seven weave-structured jute fabrics were treated using an organophosphorus-based flame-retardant (FR) chemical (ITOFLAM CPN) and a crosslinking agent (KNITTEX CHN) by the pad-dry-cure method. The thermal stability, degradation and pyrolysis behavior of jute was measured using a thermogravimetric analyzer (TGA). Surface morphology and element distribution were scrutinized utilizing a scanning electron microscope (SEM) and an energy-dispersive spectrometer (EDS). The ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared Spectrometer) technique has been employed for analyzing the composition of chemicals in the jute fabrics. According to the protocols specified in ISO 14184-1, free formaldehyde detection was carried out on the jute fabrics. The flame-retardance property was significantly improved on all of the jute fabrics after FR treatment. FTIR and SEM-EDS studies revealed the presence of FR chemical deposition on the surface of the jute fabrics. TGA analysis indicated that the fabrics treated with FR exhibited premature degradation, leading to the generation of more char compared to untreated samples. The jute fabrics specifically demonstrated a notable enhancement in residual mass, exceeding 50% after FR treatment. However, it is noteworthy that the FR-treated fabrics exhibited an elevated level of free formaldehyde content, surpassing the permissible limit of formaldehyde in textiles intended for direct skin contact. The residual mass loss percentage after ten washes of FR-treated fabrics remained in a range from 32% to 36%. Twill weave designed fabrics (FRD4 and FRD5) clearly showed a lower thermal degradation temperature than the other weaves used in this study.

Development of polysaccharide bioplastic: Analysis of thermo-mechanical properties and different environmental implications

Despite the distinct benefits of plastics, the environmental impacts stemming from their production and accumulation in the environment have become a global concern. Therefore, the development of new technologies that mitigate these impacts is of notable importance. The present study aimed to evaluate the physicochemical properties of starch-xylan-based bioplastic, and to discuss the viability of this material in terms of applications and ecological impacts. Holocellulose, xylan, and α-cellulose were extracted from waste biomass and combined with starch for bioplastic production. Solubility in food simulants (3% acetic acid, and 90% ethanol) was performed for xylan and starch-based bioplastics. Bioplastic was evaluated to grow Aspergillus versicollor for xylanase production. The bioplastic was evaluated as a photoprotector with yeast exposed to UVC light-covered by the bioplastic for 2 h. Bioplastic disintegration was evaluated in different soil moistures and the disintegration on the surface of the compost. Liquid washes from soils exposed to bioplastic biodegradation were tested for Lactuca sativa seed germination/inhibition. Water from a local lake was exposed to bioplastic and microbial cell density modification was verified. Images of the surface of the bioplastics were obtained by scanning electron microscopy, and characterized by thermogravimetric and dynamic-mechanical analysis. The xylan addition in bioplastic led to a material with a 40–50% decreased ultraviolet light transmittance. An increase in xylan concentration reduced solubility in lipid food simulant solutions, with no fatty solubilization with 25% of xylan. It suggests potential applications in photoprotective and packaging contexts. The thermal degradation temperature of the pure starch bioplastic was 324 °C, and the addition of 10% (287 °C), 15% (286 °C), and 25% (296 °C) xylan (w/w) indicated a reduction in thermal resistance, possibly due to suboptimal interaction between polymer chains. The decrease in crystallinity in the compositions 10/90% (Xc = 20%), 15/85% xylan/starch (Xc = 21%) compared to 25/75% xylan/starch (Xc = 11%) also underscored the complexity of polymer interactions within the bioplastic matrix. Tensile strength of pure starch was 1.21 MPa, while the composition of 15/85% xylan/starch exhibited improved strength 2.99 MPa. Further investigation into the interaction between starch and xylan is warranted. Concerning the disintegration of the 25/75% xylan/starch formulation in the soil, the humidity of the soil matrix played a significant role. The disintegration occurred over 5 days and 16 days in compost (55% humidity) and soil (32.6% humidity), respectively. The results of phytotoxicity (Lactuca sativa seeds) and changes in the physicochemical and biological profile of water (smell, turbidity, phosphorus and nitrogen levels, pH, and bacterial and phytoplankton density/richness), in response to exposure to bioplastics, highlight the necessity of developing this biologically-based and biodegradable technology in concerns about potential environmental impacts. Furthermore, the present study introduces the approach of bioplastic waste recycling using enzyme production biotechnology. In line with the legitimacy of bioplastics as important materials for addressing the challenges posed by their non-biodegradable synthetic counterparts, the presented results broaden the discourse on the feasibility of this biologically based material, contributing to the development of a sustainable society.