Effects Of Several Nano-materials On The Crystallization And Mechanical Properties Of Poly (Lactic Acid)

According to requirements of environmental friendly and harmless materials in automotive industry, and PLA's drawbacks, such as poor crystallization and mechanical properties, we synthesized PLA composites by solution blending method and melt blending method.. In the present work, properties of zinc lactate nano-wires/Poly(lactic acid) composites and grapheme (oxide)/Poly(lactic acid) were characterized by the means of infrared spectroscopy (IR), ultraviolet-visiable spectrophotometer (UV-Vis), X-ray diffraction (XRD) and polarizing optical microscopy (POM), atomic force microscope (AFM), differential scanning calorimetry (DSC), scanning electron microscope(SEM) and transmission election microscopy(TEM). And their mechanical properties were tested by impact machine and tensile testing machine.1. From the size of PLA spherulites, pure PLA's spherulites are about 100μm.With adding adding 1% zinc lactate nano-wires, the spherulites became smaller and more homogeneous. All of these demonstrated that nano-wires as nucleating agent, which had high specific surface area and large ratio of length to diameter, supplied more activated nuclei for the crystallization of poly(lactic acid), played a role in heterogeneous nucleation, enhanced the crystallization of PLA.From the result of Isothermal crystallization kinetics test, half crystallization time t1/2 of PLA is 9.98min under 120. Half crystallization time of PLA was reduced to 0.73 minutes from 1.29 minutes with adding zinc lactate nano-wires(0.1-2%). half crystallization time of PLA was reduced to 0.82 minutes from 2.54 minutes with adding zinc lactate nano-wires(0.1-2%) under 130℃. Zinc lactate nano-wires as nucleating agent reduced half crystallization time of poly(lactic acid).From result of PLA mechanical properties, its tensile strength, modulus of elasticity, elongation at break and impact strength had increased.2.Graphene and grapheme oxide was successfully synthesized by modified Hummer's method. And PLA/grapheme, PLA/grapheme oxide composites were prepared. With adding adding 0.1% graphene to PLA, the spherulites became smaller and more homogeneous. And its diameter was reduced to 25um from 100μm.The result demonstrate that graphene can promote crystallization of PLA. From result of PLA mechanical properties, when adding 0.1% graphene to PLA, PLA was degraded; when adding 0.1% graphene to PLA, its tensile strength, modulus of elasticity, elongation at break and impact strength had increased.