The Preparation And Properties Of Polylactic Acid/Attapulgite Nanocomposites And The Surface Modification Of Poly(Lactide-co-glycolide) Fibers

The Attapulgite (AT) reinforced polylactic acid (PLA) and poly(lactide-co-glycolide) (PLGA) fibers are prepared by melt blending and surface modification. The structure and properties of these materials are investigated. The main contents are shown as follows.1. PLA/AT nanocomposites are prepared by melt blending, and the crystallization behavior, thermal degradation kinetics and the dynamic mechanical property are investigated by various analytical techniques. DSC results show that the cold crystallization temperature increases and the enthalpy of high temperature melting peak decreases with AT contents ≤3 wt%, indicating an inhibition effect on crystallization of PLA. The cold crystallization temperature decreases and the enthalpy of high temperature melting peak increases with 8 wt% AT content, suggesting AT can promote crystallization of PLA. The crystallization ability of PLA is greatly effected by AT content. Isothermal crystallization at 106℃, the value of half-time of crystallization (t1/2) for PLA/AT nanocomposites increases and then decreases with increasing AT content. Meanwhile, the crystallization activation energy of PLA/AT nanocomposites decreases with increasing AT content. The melt isothermal crystallization kinetics of PLA/AT nanocomposites is analyzed by using of Avrami theory. The Avrami exponent n ranges from 2.34 to 2.42, which means that spherulites of PLA are formed. TGA results show that the thermal stability of PLA/AT nanocomposites increases with incorporation of AT. Thermal degradation kinetics results also confirm these results. The thermal degradation activation energy of PLA/AT nanocomposites firstly decreases and then increases with the adding of AT. The storage modulus of the nanocomposites increases with the incorporation of AT, while the Tgs of PLA/AT nanocomposites slightly increases compared with neat PLA.2. As a biodegradable material, PLGA fibers can enhance the mechanical strength of PLA. The chemical structure and morphology of alkali liquor or O2 plasma modified PLGA fibers are investigated by FTIR and SEM. The results show that, the etching surface aggravates and active groups increase with increasing the alkali concentration. A similar effect can be achieved by increasing immersion processing time. O2 plasma treatment can effectively increase the active groups on surface without changing the surface morphology of PLGA fibers.