Investigation On Properties Of One-step Prepared Thermoplastic Starch Based Biocomposites

Water proof properties of bacterial cellulose(BC)reinforced thermoplastic starch(TPS)resins were successfully improved by reacting with glutaraldehyde(GA)in their gelatinization processes.Small amounts of poly(lactic acid)(PLA)were blended with GA modified TPSBC0.02 resins to improve their processibility.TPS100BC0.02GAX,(TPS 100BC0.02GA0.5)xPLAy series specimens were successfully prepared.The tensile strengths(af)and impact strengths(IS)values of initial and aged TPS100BC0.02GAx and(TPS 100BC0.02GAx)75PLA25 specimens improved significantly and reached a maximal value as GA contents approached an optimal value at 0.5 part per hundred parts of TPS resin(PHR),while their moisture content and elongation at break(?f)values reduced to a minimal value,respectively,as GA contents approached 0.5 PHR After aging at 20?/50%relative humidity for 56/168 days,the ?f,Is and ?f retention value of aged(TPS100BC0.02GA0.5)75PLA25 specimen remained at 20.3MPa/16.4 MPa,0.7 KJ/m2/0.59 KJ/m2 and 8.7%/16.6%,respectively,which are equivalent to 82.5%/66.7%,50%/38.3%and 1.5/3 times of their initial ?f,Is and ?f values,respectively,and more than 50/82 and 7.8/11.8 times higher but 25%/29%lower than those of correspoding aged TPS and TPS10oBC0.02 specimens,respectively.As evidenced by the newly developed-C-O-C-stretching bands,weaken O-H stretching vibration bands and nearly disappeared C=O and C-H stretching bands on FT-IR spectra of TPS100BC0.02GAx series specimens,hydroxyl groups of TPS100BC0.02 resins were successfully reacted with the aldehyde groups of GA molecules during their modification processes.Clearly separated PLA droplets were found on the fracture surface of(TPS100BC0.02)75PLA25 specimen.In contrast,significantly less and smaller separated PLA droplets found on fracture surfaces of(TPS100BC0.02GAx)75PLA25 specimens.New melting endotherms and diffraction peaks of VH-type crystals were found on DSC thermograms and WAXD patterns of aged TPS or TPS100BC0.02 specimens,respectively,while no new melting endotherm or diffraction peak was found for aged TPS100BC0.02GAx and/or(TPS100BC0.02GAx)75PLA25 specimens,respectively.Possible reasons accounting for the above improved water proof and strength retention properties of TPS100BC0.02GAx and(TPS 100BC0.02GAx)75PLA25 specimens are proposed.