I t h a New York 14853-4401This paper presents the mechanical and thermal properties of unidirectional, degradable, environment-friendly "green" composites made from pineapple fibers and poly(hydrovbutyrate-co-valerate) (PHBV) resin. Tensile and flexural properties of the "green" composites with different fiber contents were measured in both longitudinal and transverse directions. Compared to those of virgin resin, the tensile and flexural strengths of "green" composites are sigmfkantly higher in the longitudinal direction while they are lower in the transverse direction. However, the mechanical properties are lower than those predicted by simple models. scanning electron microscope (SEM) photomicrographs of the tensile h c t u r e surfaces demonstrate fibers being pulled out from the matrix, the interfacial failure, fiber fibrillation, and the nonunidirectional nature of the "green" composites. The thermal behavior of the "green" composites, studied by differential scanning calorimetry @SC) and thermogravimetric analysis F A ) , showed that the presence of pineapple fibers does not affect the nonisothermal crystallization kinetics, crystallinity, and thermal decomposition of PHBV resin.

No abstract

No abstract

No abstract

ABSTRACT:The effects of 60 Co ␥-radiation on the properties of poly(hydroxybutyrateco-hydroxyvalerate) (PHBV), including the chemical, mechanical, and thermal properties, were investigated. Molecular weight of the irradiated PHBV as measured using a Ubbelohde-type capillary viscometer decreased significantly. Fourier transform infrared-attenuated total reflection (FTIR-ATR) and 1 H nuclear magnetic resonance (NMR) spectra show that chain scission was the predominant reaction in the PHBV irradiated with 10 and 25 MRad doses. The G(S) value for the chain scission was 0.9, and the number of bond cleavages per molecule was 0.22 MRad Ϫ1 . Thermal and tensile properties of control and irradiated PHBV were examined using a differential scanning calorimeter (DSC) and an Instron tensile testing machine, respectively. Results indicate that 60 Co ␥-radiation significantly affected the thermal and tensile properties of PHBV. The melting temperatures of the irradiated PHBV decreased. Tensile strength and fracture strain of the irradiated PHBV decreased dramatically, indicating increased brittleness. The fracture surfaces studied using a scanning electron microscope (SEM) showed some voids and a brittle fracture surface.