Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier

Poly(vinyl chloride) (PVC) and natural fiber composites were prepared by melt compounding and compression molding. The influence of fiber type (i.e., bagasse, rice straw, rice husk, and pine fiber) and loading level of styrene-ethylene-butylene-styrene (SEBS) block copolymer on composite properties was investigated. Mechanical analysis showed that storage modulus and tensile strength increased with fiber loading at the 30% level for all composites, but there was little difference in both properties among the composites from various fiber types. The use of SEBS decreased storage moduli, but enhanced tensile strength of the composites. The addition of fiber impaired impact strength of the composites, and the use of SEBS led to little change of the property for most of the composites. The addition of fiber to PVC matrix increased glass transition temperature (T_g), but lowered degradation temperature (T_d) and thermal activation energy (E_a). After being immersed in water for four weeks, PVC/rice husk composites presented relatively smaller water absorption (WA) and thickness swelling (TS) rate compared with other composites. The results of the study demonstrate that PVC composites filled with agricultural fibers had properties comparable with those of PVC/wood composite.     

石墨烯复合物在痕量气体分子检测中的应用

综述了石墨烯复合物的种类、性能与制备方法,以及在痕量气体分子检测中的应用。石墨烯具有大的比表面积和独特的电学性质,对一些气体分子有很强的吸附能力,制作的传感器用于气体分子检测时灵敏度较高,但选择性较差。氧化石墨烯巨大的比表面积和表面丰富的官能团赋予的优异的复合性能,可提高传感器的检测灵敏度和选择性。     

Sustainable wood-based nanotechnologies for photocatalytic degradation of organic contaminants in aquatic environment

•Wood and its reassemblies are ideal substrates to develop novel photocatalysts. •Synthetic methods and mechanisms of wood-derived photocatalysts are summarized. •Advances in wood-derived photocatalysts for organic pollutant removal are summed up. •Metal doping, morphology control and semiconductor coupling methods are highlighted. •Structure-activity relationship and catalytic mechanism of photocatalysts are given. Wood-based nanotechnologies have received much attention in the area of photocatalytic degradation of organic contaminants in aquatic environment in recent years, because of the high abundance and renewability of wood as well as the high reaction activity and unique structural features of these materials. Herein, we present a comprehensive review of the current research activities centering on the development of wood-based nanocatalysts for photodegradation of organic pollutants. This review begins with a brief introduction of the development of photocatalysts and hierarchical structure of wood. The review then focuses on strategies of designing novel photocatalysts based on wood or its recombinants (such as 1D fiber, 2D films and 3D porous gels) using advanced nanotechnology including sol-gel method, hydrothermal method, magnetron sputtering method, dipping method and so on. Next, we highlight typical approaches that improve the photocatalytic property, including metal element doping, morphology control and semiconductor coupling. Also, the structure-activity relationship of photocatalysts is emphasized. Finally, a brief summary and prospect of wood-derived photocatalysts is provided.     

Life cycle assessment of biofibres replacing glass fibres as reinforcement in plastics

This article aims to determine the environmental performance of China reed fibre used as a substitute for glass fibre as reinforcement in plastics and to identify key environmental parameters. A life cycle assessment (LCA) is performed on these two materials for an application to plastic transport pallets. Transport pallets reinforced with China reed fibre prove to be ecologically advantageous if they have a minimal lifetime of 3 years compared with the 5-year lifetime of the conventional pallet. The energy consumption and other environmental impacts are strongly reduced by the use of raw renewable fibres, due to three important factors: (a) the substitution of glass fibre production by the natural fibre production; (b) the indirect reduction in the use of polypropylene linked to the higher proportion of China reed fibre used and (c) the reduced pallet weight, which reduces fuel consumption during transport. Considering the whole life cycle, the polypropylene production process and the transport cause the strongest environmental impacts during the use phase of the life cycle. Since thermoplastic composites are hardly biodegradable, incineration has to be preferred to discharge on landfills at the end of its useful life cycle. The potential advantages of the renewable fibres will be effective only if a purer fibre extraction is obtained to ensure an optimal material stiffness, a topic for further research. China reed biofibres are finally compared with other usages of biomass, biomaterials, in general, can enable a three to ten times more efficient valorisation of biomass than mere heat production or biofuels for transport.     

Compression Molding of Phenolic Resin and Corn-based DDGS Blends

With the rapid growth in the ethanol fuel industry in recent years, considerable research is being devoted to optimizing the use of processing coproducts, such as distillers dried grains with solubles (DDGS), in livestock diets. Because these residues contain high fiber levels, they may be amendable to incorporation into bio-based composites. Thus, the goal of this study was to demonstrate the viability of using corn-based DDGS as a biofiller with phenolic resin, in order to produce a novel biomaterial. DDGS was blended with phenolic resin at 0, 10, 25, 50, 75, and 90%, by weight, and then compression molded at 51 MPa (3.7 tons/in²) and 174 °C (345°F). Molded specimens were then tested for tensile strength. Tensile yield strengths ranged from 32 MPa (4,700 psi) to 7.6 MPa (1,100 psi), while the engineering strain ranged from 0.6% to 1.25%. Results indicate that DDGS concentrations between 25% and 50% retained sufficient mechanical strength and thus represent reasonable inclusion values. Additionally, data were similar to those from other studies that have investigated biofillers. Follow-up studies should quantify the effects of altering molding parameters, including molding pressure, temperature, and time, as well as pretreatment of the DDGS. Additionally, strength of the DDGS composites should be optimized through the use of coupling agents or other additives. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the United States Department of Agriculture and does not imply approval of a product to the exclusion of others that may be suitable.     

Strategy and management for the recycling of carbon fiber-reinforced polymers (CFRPs) in the aircraft industry: a critical review

ABSTRACT

Carbon fiber-reinforced polymers (CFRPs) have attracted attention from the aerospace industry due to their light weight, excellent mechanical properties, and resistance to corrosion. However, CFRP composites are difficult to recycle as their recycling process must be performed under extreme conditions; end-of-life regulations do not directly address the problem with reusing these composites. Thus, the objective of this study is to explore solutions that minimize the use of CFRPs and prolong their useful life in the airline industry. To achieve this goal, this work conducted a review of the state of the art of CFRP fiber recycling, emphasizing the recycling processes, restrictions, and regulations. One solution is to develop a CFRP recycling market that would allow the sequential use of recycled materials among industries in descending order of the required structural performance of the composite.