Preparation And Characterisation Of Poly Lactic Acid Composite Material

Polylactic acid was regarded as one of the most promising biodegradable polymers, however, it had inherent low toughness and unsatisfactory heat resistance, which restricted the range of applications. Attapulgite clay, carbon fiber and other inorganic materials because of their unique one-dimensional rod-like structure could play a very good reinforcement, toughening effect when they were added to the polymers. The poor compatibility of the inorganic fillers and polymers, which led to the inorganic fillers can not be fully dispersed in polymer and had weak bonded to the substrate. In order to improve the ability to bind with the organic matrix and achieve reinforcement, toughening effect, the inorganic fillers must be modified before using. Secondly, the poly (butylene succinate), polyurethane and other organic elastomer were added to composite materials, which could overcome the deficiency of the inorganic filler toughening composite materials and significantly improve the mechanical and thermal properties of polylactic acid.In this study, using polylactic acid as matrix, attapulgite clay or carbon fiber as inorganic filler, poly (butylene succinate) or polyurethane as the toughening materials, the surface of the inorganic filler particles was modified by organic/inorganic combined with two mothods. A variety of polylactic acid based composite material were prepared by melt blending, then the mechanical properties and thermal stability of the composite were tested, the main results were as following:(1) Firstly the attapulgite clay was modified by silane coupling agent (Z-6030) combined with cetyl trimethyl ammonium bromide, that was the best solution of modification by modified agent compound; then the polylactic acid/attapulgite composites was prepared by melt blending, a variety of preparation conditions on the properties of materials were studied and the preparation conditions was obtained, that were:the extrusion temperature is180℃, the screw speed is90r/min, the mixing time is two minute, injection cavity pressure is650-800bar, injection cavity temperature is190℃, the mold temperature is75℃(2) The attapulgite clay was modified by lactide ring opening polymerization methods. The effects of many factors such as different pretreatments attapulgite clay, clay calcined temperature, reaction time, the proportion of lactide, reaction temperature and other factors on the graft rate influence were investigated. The polylactic acid/attapulgite clay composites were prepared by melt blending, and the effects of grafted attapulgite clay content on the mechanical properties, heat resistance, degradation and crystallization rate of polylactic acid/attapulgite clay composite was investigated.(3) The attapulgite clay was modified by lactide ring opening polymerization methods, then the composite materials of polylactic acid/poly (butylene succinate) and polylactic acid/attapulgite clay/poly (butylene succinate) were prepared by melt blending. The composite structure and the mechanical properties were studyed by FTIR, DSC, SEM, TG, XRD analysis, and heat distortion temperature, degradation and crystallization rate were tested. The addition of the poly (butylene succinate) on property of composites was studied.(4) The attapulgite clay surface was modified by silane coupling agent (Z-6030) combined with cetyl trimethyl ammonium bromide, then composite materials of polylactic acid/attapulgite clay/polyurethane composites was prepared by melt blending, the composite structure and the mechanical properties were studyed by FTIR, DSC, SEM, TG, XRD analysis, and heat distortion temperature, degradation and crystallization rate were tested. The addition of polyurethane on property of composites, acid and alkaline resistance were studied.(5) Composite materials of polylactic acid/carbon fiber was prepared by melt blending extrusion, and the surface of the carbon fiber was modified by nitric acid and cetyl trimethyl ammonium bromide, the modified carbon fiber, unmodified carbon fiber and the content of carbon fiber on the property of the composite influence with acid and alkali resistance of composites were inspected.