Research On The Preparation Of Polyoxymethylene Fiber And Properties Of Polyoxymethylene Fiber Reinforced Geopolymer Composites

POM fiber has a lot of properties like high strength, high modulus, excellent tensile recovery property, wear resistance and chemical resistance, which provided the POM fiber an excellent application value. Although geopolymer has the advantages of high strength, chemical resistance, durability, environmentally friendly and so on, the brittle property severely limited its applications in many fields. A type of new fiber-reinforced geopolymeric composites was developed by combining metakaolin and POM fibers in this paper. High-strength POM fibers were first prepared through melt spinning followed by a hot-drawing procedure, then studied on the influence of melt index of the resin used in the preparation of POM fiber and drawing ratio on the properties of POM fiber. It’s concluded that hot-drawing procedure could enhanced the mechanical properties of POM fiber by increasing the orientation and crystallinity of POM fiber; the maximum drawing ratio of POM fiber increases with the increase of the melt index of the resin used in the preparation of POM fiber. Considering the cost and mechanical properties of POM fiber, we used the fiber prepared by the resin with a melt index of 27g/10min to reinforce the geopolymer. The tensile strength of the fiber is 925MPa, elastic modulus of the fiber is 15.21GPa and elongation at break of fiber is 15.6%. A series of metakaolin-based geopolymeric composites with different contents and length of POM fibers were synthesized by combining POM fibers and geopolymer. The mechanical and tribological properties of the resulting composites were evaluated, and the morphology and microstructure were investigated. The POM fibers provided significant mechanical reinforcement for the metakaolin-based geopolymer. The composites were optimized for flexural and compressive strength with respect to fiber content and fiber length. Compared to unreinforced geopolymer, the composites obtained an optimum improvement by approximate 150% in flexural strength and by almost 26% in compressive strength. Moreover, the longer POM fibers exhibit a better reinforcement effect on the geopolymer, resulting in a lower optimal fiber content for the composites to achieve the maximum mechanical data. The reinforcing mechanisms were discussed on the basis of morphological investigation and considered as accumulative energy-dissipating effect by fiber pull out and orientation, fiber rupture, fiber debonding from the matrix, and fiber bridging within cracks. The geopolymeric composites also achieved a considerable reduction in friction coefficient and abrasion loss rate in the presence of POM fibers. Such an enhancement of tribological performance is ascribed to the formation of self-lubricating transfer films between the contacts urfaces of composites against the steel counterpart.