Glass Fiber Reinforced Plastics (GFRP) have been used for various applications such as automobiles, motorboats and so on. Since GFRP in which thermosetting resins are used as a matrix is difficult to recycle, thermoplastic resins superior in recyclability have been receiving attention. Especially, polylactic acid (PLA), which is plant-derived and biodegradable resin, has been receiving attention as an environmentally friendly material. When PLA is used as a matrix of FRP, it is necessary to suppress hydrolysis at the time of use as in ordinary petroleum-based plastics. Recently, a method to decrease the rate of decomposition of PLA has been developed by combining a decomposition inhibitor (Poly Methyl Methacrylate: PMMA) with PLA and annealing treatment. For a decomposition inhibitor PMMA, in which the methyl ester group protects the ester group of PLA, suppress the hydrolysis during use. By performing an annealing treatment, the degree of crystallization of PLA is increased and the progress of hydrolysis can be delayed. As described above, although PLA with higher resistance to hydrolysis have been developed, the mechanical properties of GFRP using PLA decomposition inhibitor as a matrix have not been clarified yet. In this study, single fiber pull-out tests were conducted by using GF/PLA model composites to clarify the influence of decomposition inhibitor and annealing treatment. Though the fiber/matrix interfacial shear strength was decreased by water absorption, the decomposition rate for GF/PLA with a decomposition inhibitor and annealing treatment was the lowest and showed excellent water resistance.
Glass fiber reinforced plastics (GFRP) have many superior mechanical properties, such as high-specific strength and high-specific stiffness, and inexpensiveness compared with CFRP. Since the traditional matrix of GFRP such as epoxy, is not decomposed in the natural environment, polylactic acid (PLA), which is a plantderived and biodegradable resin, has been receiving attention as an environmentally friendly material. Although good durability is required as in normal petroleum-based plastics when PLA is used for a matrix of FRP, PLA is expected to decompose quickly at the end of its lifetime. However, since the decomposition rate of PLA in the natural environment is very slow compared with other biodegradable resins, it is difficult to process a large amount of PLA in the natural environment. Recently, a method to control the rate of degradation of PLA has been developed by combining a decomposition accelerant and a degradation inhibitor with PLA. However, the influence of water absorption on the mechanical properties of PLA as the matrix of fiber reinforced composite materials has not been clarified yet. In this study, single fiber pull-out tests were conducted to clarify the influence of water absorption on the fiber/matrix interfacial shear strength of glass fiber reinforced degradation controlled PLA. The degradation inhibitor and the degradation accelerator are considered to suppress and accelerate the decomposition of PLA hydrolysis by water absorption respectively. The fiber/matrix interfacial shear strength of water absorbed specimens made with
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