Search

Global regulations are guiding society towards more sustainable material solutions. This increasing awareness of the need for environmentally friendly alternatives has led to a greater emphasis on biocomposites, which combine natural fibers with bio-based polymers. This study investigates how bleached softwood pulp fibers (BSWPF) and unbleached softwood pulp fibers (UBSWPF) affect the characteristics of poly(lactic acid) (PLA)-based biocomposites. UBSWPF is a more cost-effective option because it is manufactured with less processing steps than BSWPF. However, it is largely unexplored as a reinforcement in biopolymers. Through investigating the mechanical, thermal, and morphological aspects of the biocomposites, this study showed that UBSWP increased the modulus and impact strength of the PLA biocomposites better than BSWPF. The impact strength, modulus, and tensile strength of PLA-BSWPF and PLA-UBSWPF improved as the fiber content increased. However, a decrease in tensile strength was seen at higher percentages of UBSWPF in PLA. Despite the decrease in tensile strength at higher UBSWPF concentrations, both types of fibers improved the mechanical properties of the biocomposites, demonstrating a potential sustainable reinforcing material for PLA biocomposites. [ABSTRACT FROM AUTHOR]

All-cellulose composites (ACCs) have been fabricated by using a variety of cellulosic sources, versatile technologies, and are sustainable alternatives for traditional composites. In this study, nonwoven-woven ACC laminates were created from wood-based Spinnova short fibers and Lyocell fabrics via partial dissolution and an NaOH-urea solvent system. The less-known wood-based Spinnova fiber is created for the textile industry, but it also has great potential for the composite industry. To identify the mechanical properties of ACCs--which greatly influence the range of material application--tensile, impact, and flexural tests were conducted. The mechanical properties indicated only moderate properties, which are influenced by high porosity and weak fiber bonding. Despite this, valuable information on the nonwoven-woven structured ACCs was obtained. To improve the ACC laminate's ability to resist moisture, biobased coatings (e.g., commercially available birch bark betulin and suberin acid mixture) were applied on the surface of ACCs and it successfully improved the wetting resistance. The results of contact angle analyses demonstrated that the highest contact angle of 128° was measured for betulin-coated laminates and the best stable hydrophobicity calculated a minute after the beginning of the experiment were observed at 109° for the uncommercial pressurized hot ethanol (PHE) extract of birch bark. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelets (GNP) were incorporated into thermoplastic starch (TPS) films, and effects on water absorption and mechanical properties were investigated. GNP inclusion formed a barrier that significantly reduced water absorption, resulting in denser TPS/GNP films. Fourier-transform infrared spectroscopy (FTIR) revealed changes in chemical interactions, and FESEM analysis showed improved GNP dispersion at this concentration. Water contact angle results indicated increased hydrophobicity with higher GNP content. Positive influences on mechanical properties, such as tensile strength and Young's modulus, were observed at 12 wt% GNP, but excessive GNP content caused agglomeration and reduced ductility. The study results highlight the potential of GNP-reinforced TPS films for improved water resistance and mechanical properties, emphasizing the need for careful optimization in future research. [ABSTRACT FROM AUTHOR]

Recently, new brake pads have been developed using sustainable materials that are not harmful to the environment. In this study, the effect of using blue-colored Cupressus arizonica cones was determined as a friction modifier in brake pad composites. Four different samples were prepared by grinding the cone material. The samples’ physical and chemical properties and performances were compared, and finally, their microscopic analyses were visualized by scanning electron microscopy. Maximum friction coefficient and minimum wear rate are required for brake pads. The maximum friction coefficient of 0.39 and the minimum wear rate of the samples containing Cupressus arizonica were obtained in the 0.124X10-7 cm³ /Nm BCA3 sample. When the brake pads developed from lignocellulosic biomass were compared, it was determined that the BCA3 sample met the most reasonable performance values. [ABSTRACT FROM AUTHOR]

The effect of the chemical treatment of paper mill sludge fibers and polypropylene molecular weight were studied relative to the physical, mechanical, and morphological properties of a novel cellulosic biocomposite. Paper mill sludge fibers were treated with acetic anhydride, and succinic anhydride was mixed with maleic anhydride polypropylene (MAPP) and coupling agent (0 and 3%). The ratio of fibers and polymer materials was considered 30 to 70, which was manufactured by the hotpressing method at 180 °C. Water absorption, volume swelling, and contact angle were examined on each specimen according to ASTM standards, while Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) explored the efficiency of chemical modification of fibers and the morphology of biocomposites, respectively. The results showed that chemical treatment of fibers reduced the water absorption and volumetric swelling. Both tensile and flexural strength were increased with chemical treatment using the coupling agent. Comparison of fibers treated with succinic acid and acetic acid showed that the succinic acid enhanced the mechanical properties better than the acetic acid treatment. Finally, FTIR analysis showed that the hydroxyl groups decreased, and SEM images indicated the interface between fibers and polypropylene improved via chemical treatment of sludge fibers. [ABSTRACT FROM AUTHOR]

Bioderived poly(lactic acid) (PLA) is a promising alternative for fossilbased polymers, but its poor hydrophilicity, high brittleness, and low heatresistance are problems for its utilization. In this work, bleached softwood kraft pulp (BSKP) fiber was adopted to modify PLA with MAPP as the coupling agent, with BSKP accounting for 10 wt% to 50 wt%. Internal mixing (IM) was applied to mix the PLA/fiber blend instead of screw grinding. The thermal and mechanical properties of the composites were assessed. The IM process was proven qualified for its effective dispersion of BSKP fibers in the PLA matrix. At a fiber loading of 50 wt%, IMprocessed composites acquired satisfactory tensile strength (50.49 MPa, slightly higher than PLA) and Young's modulus (2.56 GPa, 45.8% higher than PLA). The pulp fillers matched PLA matrix well for the characteristic temperatures in thermal decomposition. The BSKP/PLA composites were thermally strengthened by pulp fibers characterized by higher content of residues. The fibers improved the interfacial crystallinity of PLA in the composites (i.e., from 5.22% to 11.86%). The increased crystallinity resulted in enhanced stiffness or weaker damping performance of the composites. In conclusion, natural plant fibers are a feasible option to modify PLA for extended applications. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis wood becomes residue at plantations in Malaysia. In this study, these residues were reinforced into silicone rubber to produce a new soft biocomposite (Hevea brasiliensis-silicone biocomposite). The newly introduced soft biocomposite has potential for use in cushioning and sealing applications. The specimens were prepared with five different compositions (0 wt%, 4 wt%, 8 wt%, 12 wt%, and 16 wt% fiber content). Tensile tests were conducted according to ASTM D412 (2008) to assess the mechanical properties. Morphological characteristics were analyzed from the fractured surface of specimens. Stress-stretch data was used to quantify the non-linear tensile behavior, which was based on Neo-Hookean, Mooney-Rivlin, and Ogden hyperelastic constitutive equations. An increase in fiber content improved the modulus of silicone rubber. However, it reduced the flexibility and elastic properties of the silicone rubber biocomposite. The increasing material constant values supported these findings. The hyperelastic models accurately represented the behavior of the Hevea brasiliensis-silicone biocomposite. This study contributes knowledge towards a better understanding of the mechanical behavior of Hevea brasiliensis-silicone biocomposites. [ABSTRACT FROM AUTHOR]

Silicone rubber biocomposites were prepared with 0%, 4%, 8%, 12%, and 16% bamboo fiber as reinforcement. The compressive set behavior of the samples was compared between the samples that were tested before and after immersion in water. The compression set values for the samples that were immersed in the water were lower than the samples that were not immersed in the water. The moisture absorption rate of the bamboosilicone biocomposites (BaSiCs) increased as the bamboo fiber content increased. As the bamboo fiber content in the BaSiCs increased, the impact energy and the deflection at peak load values decreased and increased, respectively. The results from this study showed that the addition of bamboo fiber into silicone rubber composites can substantially affect its compressive strength, moisture absorption, and impact strength. This study provided essential knowledge to the development of BaSiCs for cushioning applications, such as shoe insoles. [ABSTRACT FROM AUTHOR]