Electronic Thesis and Dissertation Repository


Master of Engineering Science


Mechanical and Materials Engineering


Takashi Kuboki


Enhancement of mechanical properties of the bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) by the addition of glass fibers (GF) and thermoplastic elastomers was investigated. Glass fiber addition significantly increased Young’s modulus and strength of PHBH, but had little effect on the degree of crystallinity of PHBH. To increase ductility and/or energy absorbed in fracture, that were found to be reduced, in glass fiber reinforced PHBH composites, two types of thermoplastic elastomers, styrene-ethylene-butylene-styrene copolymer (SEBS) and maleated styrene-ethylene-butylene-styrene copolymer (SEBS-MA), were added to PHBH/GF composites. SEBS-MA was more effective than SEBS in improving ductility, fracture energy, and notched Izod impact strength of PHBH/GF composites. Both SEBS and SEBS-MA addition decreased the degree of crystallinity of PHBH/GF composites. In conclusion, it was found that mechanical properties of PHBH can be tailored by the addition of glass fibers and thermoplastic elastomers; therefore, modulus, strength, and energy absorption in fracture of PHBH composites can be balanced.