Effect Of Different Premix Technique And Modification Treatment On The Mechanical Properties Of Flax Thermopiastic Composites

Compared with other mineral fibers such as glass fiber, flax fiber is abundant and easy to cultivate. It can degrade naturally and it has higher specific strength and specific modulus. Flax fiber could be used as an ideal reinforcing material of environmentally friendly composites. Recently, thermoplastic resin composites reinforced with fibers like flax, ramie, sisal have developed largely and quickly. The products have been applied to architecture, auto, and traffic and so on. In this paper, the flax yarn will be used as the continuous reinforcement and the Polypropylene multifilament will be used as thermoplastic rein matrix. The flax/PP composite boards will be developed and researched.Two different premix technique, co-weave technique and co-wrapped yarn technique were used to make different plain-weave performs. The flax/PP composites boards were accomplished by hot-pressing molding. Some other composites were also produced, whose performs made by co-weave technique had been alkali and coupling agent treated. The effects of different premix technique on the effective infiltration, tensile and peeling properties of thermoplastic performs and composites were investigated. The effects of different processing methods and concentration on the tensile and peeling properties of thermoplastic composites were also researched.The even distribution of flax and PP in the yarn that giving a better mixture of the matrix and reinforcing material was achieved by co-wrapped yarn technique. Then the co-wrapped yarns were made into performs and composites. The co-wrapped yarn technique could overcome the difficulties of rein penetrating during the composites processing. The flax yarns and PP multifilament were produced into fabrics by co-weave technique which could be directly handled during composites molding. The co-weave technique could simplify the technology of composite processing. It was found that, the basic properties of performs made by two different premix technique were similar, while the effective infiltration of composite by co-wrapped yarns was better and with lower void interface than that of composite by co-weave process, and the tensile strength was higher 46% and the peeling force was higher 39% than that of composite by co-weave process, respectively.The tensile and peeling properties of composite boards, whose performs by co-weave process had been tentatively treated by 2% NaOH and 1% KH570 were tested. These composites were also analyzed by SEM and DSC. It turned out that, the tensile and peeling properties of treated composites were better while the effect was not obvious.The effects of different treated concentration on the tensile and peeling properties of thermoplastic composites were investigated. It was found that, the effect of alkali treatment on the tensile strength of composites was more obvious while the coupling agent treatment had more effects on the peeling force of composites. When concentration of NaOH reached 5%, the tensile strength was best and higher 30% and the peeling force was higher 19% than untreated composites, respectively. When concentration of KH570 reached 2%, the peeling force was best and higher 50% and the tensile strength was higher 22% than untreated composites, respectively. Experiments proved that, modification treatment assuredly had improved the interface compatibility between the reinforced material and rein matrix.