The effects of sago pith as a bio‐filler (SPB) on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) were studied. The SPB was obtained from sago pith waste after starch extraction from sago palm. Sago pith waste was dried and ground to produce SPB. The SPB was blended with PVA in a twin‐screw co‐rotating extruder in order to produce PVA‐SPB composites for mechanical, morphology, and thermal analyses. Blending of SPB and PVA improved the tensile modulus, whereas the tensile strength was reduced. This result occurred because SPB increased the rigidity of PVA. However, lack of interfacial adhesion between PVA and SPB caused the loss of reinforcing effects. The morphology analysis showed that a high loading of SPB (>70 wt%) tended to form clusters, as implied by the presence of elongated cavities due to droplet coalescence restricting chain mobility. Besides that, the enthalpy of melting (ΔHm) for 50 wt% of SPB was higher than that of PVA. This observation means that the molecular interaction forces between PVA and SPB were so great as to overtake those of the PVA itself. Thus it was concluded that 40–50 wt% of SPB was preferably blended with PVA to form a biodegradable composite in order to reduce the overall materials cost, rather than to act as a strong reinforcing filler. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers

A series of blends of sago pith waste (SPW) and poly(vinyl alcohol) (PVA) were prepared. Mechanical and water absorption properties of the composites have been investigated. In this study, variable amounts of plasticized SPW (pSPW) and PVA (pPVA) were processed in the presence of glycerol as plasticizers. Composites were compression molded and evaluated. The addition of pSPW reduced the tensile properties of the composites, lowering the elongation and increasing Young's modulus. The reduction in mechanical strength with the addition of pSPW was a general phenomenon due to the poor interfacial adhesion between the pPVA and Pspw, which can be proved by the scanning electron microscope observations. The percentage of water absorbed of the pPVA/pSPW biocomposites was higher than either the pPVA or pSPW alone while pSPW showed better water resistance compared to pPVA because of the restricted mobility exerted by the cellulose fibers. The incorporation of SPW into PVA decreased both the mechanical and water absorption properties.

In this study, blending of poly (vinyl alcohol) (PVA) and sago pith waste (SPW) was prepared by a one-step melt extrusion. The physico-mechanical, Fourier transform-infrared (FT-IR), moisture sorption, rheological, and thermal characterization were conducted. Incorporation of PVA in SPW improved the tensile modulus, whereas the tensile strength reduced. The FT-IR analysis has shown that SPW could be introduced into the PVA network via the formation of hydrogen bonds between the PVA and SPW clusters. The interaction between PVA and SPW macromolecules has shown that there is a noticeable improvement in the water sorption ability. The rheological properties revealed that the PVA/SPW composites exhibited shear-thinning behavior and the blend viscosities increased with the rise in SPW content because of its rigid structure. Thermal analysis revealed that >50 wt% of PVA could induce greater molecular interaction between the PVA and SPW.