| Poly lactic acid (PLA) fiber (also called corn fiber) is a kind of biodegradable polymer fiber material which is produced with renewable corn as raw material. Because the raw material of PLA is renewable, PLA fiber can solve the shortcoming of traditional polymer material’s dependence on limited petroleum resources. Poly lactic acid can be completely decomposed into water and carbon dioxide in soil or water, which will not cause any pollution to the environment, so poly lactic acid is a kind of environmental friendly material and solve the problem caused by the synthetic fibers (such as polyester, nylon and others) whose waste is nondegradable and pollute environment. Poly lactic acid fiber is widely applied in manyl fields, from the medical field in an early stage, to the developing textile and clothing field.There is a serious problem when poly lactic acid fiber is applied in textile and clothing field. Poly lactic acid fiber can be used normally at room temperature, but once the increased temperature is over the glass transition temperature (Tg≈57℃), the mechanical properties of polylactic acid fiber and its textile would decline sharply, and become deformed or sticky. At the same time, as the poor heat resistance, polylactic acid fiber and its fabric can’t use the conventional high-temperature dyeing method and have bad ironing performance. And by now, the heat resistant modification for polylactic acid fiber has become one of the hottest research point in the field of polylactic acid fiber.This paper used nano-composite technology to modify PLA filament. The nano-SiO2as nano-inorganic material with good function of environmental protection and nonpoisonous, was choosed as heat-stabilizer, and is modified by the silane coupling agents KH-550and KH-570, in order to prepare the nano-SiO2with good dispersibility. After that, the modified nano-SiO2was blended in PLA filament through master-batch melt-spinning method, in order to prepare the PLA/nano-SiO2composite filament which possess good heat resistance and completely environmental friendly performance. The composite filament was spun as yarn through doubling and twisting process and heat seting process. At last, the PLA/nano-SiO2composite fabric which have good heat resistance, was woven.Based on the preparation, structure and properties of nano-SiO2modified by coupling agents, PLA/nano-SiO2composite master-batch, filament, yarn and fabric, and the mechanism, the results indicated that:(1) The silane coupling agents KH-550and KH-570were used to modify nano-SiO2and substitute the hydroxyl groups on nano-SiO2surface, which improved the dispersability of nano-SiO2and prevented generating gobbet. And the optimal modification process was obtained.(2) The modified nano-SiO2and PLA were made as composite master-batch firstly, which could control the weight proportion of nano-SiO2with PLA, and improve the uniformity of nano-SiO2in PLA. And the optimal drying process was obtained.(3) The PLA/nano-SiO2composite filament with excellent heat resistance was made by melt spinning. The optimal spinning process was obtained. The results also show that the1%SiO2was blended into PLA with good dispersability, which improved the filament’s crystallinity, orientation, tensile strength and friction coefficient, and its thermal decomposition temperature raised8.2℃and glass transition temperature raised7.6℃. At last, the heat resistence of filament was improved, meanwhile, the other properties were not significantly become worse.(4) The PLA/nano-SiO2composite filament yarn was spun through doubling and twisting process and heat seting process. The optimal spinning process was obtained. The yarn had smooth and bright surface, and excellent integrity and wearing quality which were good for weaving process, and good mechanical properties.(5) The PLA/nano-SiO2composite filament fabric was woven. The fabric had clean, smooth and bright surface; and had higher tensile strength, bursting strength and tearing strength; and was very soft and pliable; also had good drapability, air permeability and wrinkle resistance; its LOI was29.1which mean difficult-flammability.(6) The interface structure of nano-SiO2/PLA was constructed. And the mechanism, why the nano-SiO2improved the heat-resistant of PLA, was analyzed. |
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