The Modification And Performance Of Biodegradable Poly (Lactic Acid) Films

Derived from renewable resources of polylactic acid(PLA)is a kind of good performance and biodegradable material,but due to its inherent brittleness seriously affect its application.This article chooses 1,4－bis(tert-butyl dioxy isopropyl)benzene(BIBP)and poly(butylene adipate-co-terephthalate)(PBAT)to modify PLA,using twin screw compounding extruder and then blowing films,PLA blends and films were prepared.The main contents and conclusions are as follows:To improve the thermal stability and mechanical properties of PLA,BIBP(0-0.4%)as crosslinking agent was introduced into the PLA.The PLA/BIBP samples were characterized by Fourier transform infrared spectrometry(FTIR).The gel fraction and degree of swelling of PLA/BIBPx were studied.The thermal and thermal degradation properties of samples were also investigated by means of differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA),the thermal stability of the samples was improved by the addition of BIBP.The complex viscosity(η*),storage modulus(G’)and loss modulus(,G")were increased with the increase of BIBP content from rheological measurement.The mechanical properties of the PLA/BIBP blends and PLA/BIBP films were tested by tensile tests,the blends tensile strength was enhanced due to the crosslinking effect of BIBP.The 0.2%BIBP was an optimal content for the PLA/BIBP blends with the best mechanical properties,while the 0.1%BIBP was an optimal mechanical properties for PLA/BIBP films.The morphology of the tear fractured surface about the films was also studied PLA/BIBP0.1 film revealed more clearly layered structure than PLA.BIBP can improve the toughness of PLA.Blown films of PLA/PBAT blends were prepared,BIBP as crosslinking agent.From WAXD results,PLA/PBAT/BIBP involved all the diffraction peaks were consistent with PLA and PBAT.For the DSC curves of PLA/PBAT/BIBP films,there were two glass transition temperature and two melt temperature,there existed two step decomposition in the DTG curves.Both Han plots and Cole-Cole plots indicated high homogeneity of the 40/60/0.1 PLA/PBAT/BIBP blend.SEM micrographs of the films revealed more ductile deformation with increasing PBAT content and 40/60/0.1 sample had better miscible compared with others.Tensile tests indicated that the elongation at break of the PLA/PBAT/BIBP films were increased with increasing PBAT content and the values of the tensile strength in the machine direction were higher than those in the transverse direction for the PLA/PBAT/BIBP films.The addition of PBAT,enhanced the toughness of the PLA/PBAT/BIBP films.From tear test and heat sealing test,the 40/60/0.1 PLA/PBAT/BIBP film exhibited the highest tear strength and the sealing strength among all the samples.This research of films is beneficial to broaden the application of PLA in the field of packaging and mulching film.