Study On Toughening Of Poly(Lactic Acid) And Properties

Biodegradable polymers have received much more attention in recent years because of plastics waste pollution of the environment. Poly(lactic acid)(PLA) is a kind of excellent biocompatibility, and completely biodegradable and synthetic polymer materials. PLA has good physical and processing properties, degraded to carbon dioxide and water, no pollution to environment after being abandoned. PLA is also known as green plastic and has become the research focus in recent years. Though PLA has high modulus, strength and good processing properties, there are also some disadvantages such as hard and brittle properties, poor toughness, elasticity and flexibility, poor resistance to heat, and bending and deforming easily, which limits its application range.Poly (butylene adipate-co-terephthatate)(PBAT) which is synethesized by oil-based materi-als is a kind of completely biodegradable material, and has very good flexibility.PBAT and talcum powder are used as the PLA’s toughening agents and nucleating agent, respectively, and silane coupling agent (KH-560) as the modifier of PLA/PBAT blends and talcum powder. Mechanical properties and crystallization kinetic before and after modification of PLA were studied. The main work are as follows:1. The mompatibility between PLA and PBAT was analysized by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The results showed that PLA and PBAT were partially miscible. To some extent, the compatibility between PLA and PBAT was improved by the silane coupling agent (KH-560).2. The fracture behavior of PLA has changed from the brittle fracture into ductile fracture by mechanical properties test and scanning electron microscopy (SEM) observation. The blends have good tensile strength, elongation at break, and elastic modulus when PBAT content was20wt%in the blends. The mechanical properties of the blends have been improved obviously by the modification of silane coupling agent (KH-560). The mechanical properties of blends became worse due to the addition of talcum powder. The optimum impact strength of PLA/PBAT blends has been achieved by the modification of silane coupling agent (KH-560) when PBAT content was20wt%in the blends.3. Effect of PBAT and talc on crystallization rate of PLA was discussed in detail by the differential scanning calorimetry (DSC). Experimental results showed that talc accelerated crystallization rate of PLA markedly, and PBAT made it easies to crystallize, and synergistic effect of PBAT and talc on PLA crystallization was found.