Preparation And Tensile Properties Of Weft-knitted Composites With Bamboo And Polypropylene Fiber

As a natural fiber, bamboo fiber has antibacterial, antimicrobial, anti-ultraviolet radiation and other characteristics. It is a green product to adapt to world development trend. Development and research of bamboo product is propitious to reasonably exploit bamboo resources in China. It will promote the upgrade of national forestry and textile industry.Textile reinforced material is included woven fabric, braid and knitted fabric. Compared with other textile structural composites, the research on the thermoplastic weft-knitted fabric composites is still limited. The majority researches are based on rigid composites. Due to the weft-knitted fabric characteristic, since the 1990's, foreign studies in this field are increasing and deeper. The research involved in the mixing ratio of flexible composites weft-knitted fabric reinforced materials (bamboo fiber) and substrate material (PP), the choice of knitted fabric organization structure, the processing control of thermoplastic weft-knitted fabric composites. I observe the infiltrate performance of composite material and study tensile properties of products. The thesis aims at affording theoretical and experimental basis for design, manufacture and required mechanical properties of thermoplastic weft-knitted fabric composites.The commingled yarn from bamboo fiber yarn and polypropylene (PP) yarn was used as knitting material in the thesis. By experimental work and theoretical analysis, the author investigated the knittability of weft-knitted fabrics form the commingled yarn. The knitting technology of plain, rib and Milano rib fabric which were produced on a STOLL computerized flat knitting machine was explored. The author discussed some factors influencing knitting process and fabric quality, such as input yarn tension, taking-down tension, sinking depth. The key technique and optimal parameters for the shaping of the bamboo/PP weft-knitted fabrics were found.After the weft-knitted fabrics were manufactured, the hot-press method was used to produce composites. By the tests, the author obtained the suitable hot-press parameters including temperature, pressure, retentive time, the method of temperature-drop etc, and then discussed the effect of the mechanical properties of the composites on the change of the hot-press parameters. At the same time, the author made the cross-ply plain hot-press composites by three different proportion commingled yarn, research influence of layer composites.Tensile tests in the wale and course direction of composites specimens were carried out to examine their stress-strain curve with origin 8.0 software. According to the stress-strain curve, the author calculate tensile fracture characteristic parameters. From curve and tensile performance parameters, it is analysis on the tensile fracture sample composite performance, including the fabric structure, bamboo fiber volume content. Meanwhile, according to hot-press temperature and pressure and time to maintain, the author took an orthogonal experiment and used significant judgment. Finally, three major hot-press molding parameters are obtained, including hot-press temperature and pressure and time to maintain...