| Degradation of environment, scarcity of resource and energy crisis have been promptingpeople to realize the importance of environmental protection and the urgency to improveresource utilization as well as sustainable development. The composite material possessessignificant roles in the field of engineering material because of the advantage of highstrength. However, the problems in energy consumption, material waste and recyclingcannot be ignored. Therefore, it is urgent to reduce the energy consumption of thecomposite material and solve the problem of the material regeneration and recycling. Thenatural plant fibers are of lower price and mass, and it could be naturally degraded. Thefully biodegradable green composite material which is made of degradable resin andreinforced with plant fibers has a promising industrial prospect. The research anddevelopment of green composite materials is becoming a hot topic. Since the1980s,scholars began the study of plant fiber and great progresses were made. At the same time,the studies about the cellulose fiber and the thermoplastic resin/thermosetting compositesalso catch plenty of attention. The real green composite material, in a strict point, shouldbe made of renewable source and can be fully biodegradable, which is the hot topic in thecomposites field currently.Jute fiber, used in this study, is a promising and biodegradable green fiber and isbeing increasingly used as reinforcement in polymer composites due to its low cost, lowdensity, high specific strength, and renewability. Traditional epoxy and bio-based epoxy,as comparison, are also used in this study. Nowadays, the researchers are mainly aimed atthe property comparison between different reinforcement and matrix composites,different molding methods and the improvement of the interface combination. However,this type of green composite material has a feature, which is the point of this study: waterabsorption in natural fiber polymer composites is a serious drawback for their potentialoutdoor applications. In this research, ordinary and bio-based epoxy polymers that werereinforced with new and recycled jute woven fabrics were subjected to water immersiontests in order to study the effects of water absorption on mechanical and geometricalproperties. Several composite specimens were made, using an open mold, according toASTM D638,which are in three compositions: pure resin, pure resin with a single jutefabric layer, and pure resin with two jute fabric layers. The effects of fiber content onwater absorption, thickness swelling, and volume swelling were measured as a functionof immersion time up to460hours. It was observed that types of resins and fiber contentshave an influence on the water absorption of the composites. Water absorption andswelling were higher in the bio-based composites than the ordinary epoxy parts, andwater absorption and swelling increased with increasing fiber content. By means of fittingexperience data in Minitab, the empirical formulas are given in order to calculate theparticular rate of water absorption、thickness and volume. The effect of the immersiontreatment on the tensile strength was also investigated. The stress of composites wasdecreased and the strain was increased after water immersion. The possible reasons for the appearance of micro-cracks in the composites and plasticization of the matrix-fiberinterface were discussed. The study of water absorption, swelling, and tensile strength inboth ordinary and bio-based epoxy composites made from woven jute fabrics in thisthesis gives a better understanding of how natural fiber reinforced composites behave inwet conditions. And open a door for further development and applications of greencomposite material. |
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