| With the improvement of living standards, the using cycle of textiles becomes shorter and shorter, the number of discarded clothing and textile mills’ scrap materials is relatively significant. China annually emits large amounts of fiber-related waste, which not only results in a staggering waste, but also causes more and more pollution on the environment, and also hides fire hazard. So how to take these wastes to be recycled and used so as to manufacture high value-added products is urgent.Fiberboard industry is one of the important industries in China’s national economy, fiberboard produced by a variety of techniques has wide applications in architectural decoration and furniture industry. If the waste textile fibers were made into sheet metal, they will not only reduce the pollution to the environment, but also turns waste into treasure and conserve resources which kill two birds with one stone.This paper selected cotton and hemp fibers with a large proportion in waste textile fibers as enhanced materials, together with PLA, they were made into composite fiberboard with the melt-mixing and hot-pressing method. The factors that affected waste cotton/hemp-PLA mechanical properties of composites were researched and they were optimized to get a preparation process. In the same time, the waste cotton/hemp fibers and PLA flame retardant system was detected, combined with materials’mechanical properties and flame-retardant effect, orthogonal experiment and single factor analysis were done to get optimal process of flame retardant waste cotton/hemp fibers. Finally, the degradation performance of sheet was researched. The conclusions are as following:(1) Waste cotton, hemp fibers, and excellent biodegradable PLA particles can be prepared biodegradable flame retardant green fiber sheet of excellent performance. This study conforms to China’s circular economy, low-cost processing strategy for sustainable development requirements. The research of this topic will help enhance the textile waste reduction, green harmless, ecological resources, processing technology level, its use and promotion will produce good economic and social benefits. (2) Through with PLA, waste cotton and hemp fibers and PLA particles were prepared composite materials of excellent mechanical properties. Primary and secondary orders of factors that affected the mechanical properties of the composite were increasing PLA> fiber length>hot pressing temperature> mix ratio of cotton and hemp. The effect of increasing PLA was the most significant, and then fiber length, hot pressing temperature and mix ratio of cotton and hemp were the least of all. At the same time the optimal process of waste cotton/hemp-PLA composite materials by blends mastication was fiber length of10mm, increasing PLA amount of45%cotton/hemp ratio50/50, the hot pressing temperature180℃,in this condition, the fiber board’ tensile strength was24.84MPa, bending strength was80.45MPa.(3) Joining talc, of which the PLA mass fraction was1%, could play the role of a nucleating agent in the PLA matrix, which could improve the crystallization rate and crystallinity of PLA, so as to make the tensile strength increased by14.8%, the bending strength improved to18.3%.(4) The main factor that affected waste flame-retardant cotton/hemp-PLA mechanical properties of composites and flame retardant was increasing PLA and flame retardants. When ammonium polyphosphate was used on fibers, flame-retardant effect was the best when DBDPE+ST formula was used on PLA particles, but with the addition of flame retardants, the mechanical properties were decreased apparently. Optimal process for the preparation of flame retardant waste cotton/hemp-PL A fiber was increasing PLA amount50%, hot pressing temperature of180℃, with30%amount of polyphosphate solution soaking cotton and hemp fibers and then drying, adding20%of DBDPE+ST flame retardant, the fiberboard tensile strength was24.83Mpa, bending strength was68.20Mpa and oxygen index was31.2.(5) In natural conditions, mass loss of the product degradation was slow, which would not affect its life cycle, but the mass loss was comparatively large in acidic or alkaline environment. At the same time, burying into the ground treatment could also make flame retardant waste cotton/hemp-PLA fiberboard degradation, which brought less pollution on the environment. |
