Surface Modification Of Polypropylene Fibre And Its Application In Engineering

Polypropylene fiber is a kind of organic synthesized fiber by chemical method, which elastic simulate is lower than cement-based material. As polypropylene fiber has virtues of good mechanics properties and enduring chemic corrasion, which can be used improve resisted tensile stress and toughness. But polypropylene fiber is one kind of water-repellent material, which has smooth surface and low surface energy, and whose molecule has not any reactive functional group. When the fiber is added in cement-based material, there will be a problem of fiber's poor performance of dispersion in the matrix and bad binding capacity between fiber and matrix. So it is important to modified surface of PP fiber that improving disperse of fiber and cement matrix and increasing combination in the interface, which is the key of application of PP fiber.The author starts with surface modification, and expects to solve the problem mentioned above by introducing hydrophilic reactive functional group into fiber and (or) increasing the degree of coarseness of fiber's surface.In this paper two modified methods are used, some kinds of influenced factors have also been studied, the best disposed condition and conclusion of surface modification are shown as followed:(1) Grafting silane on PP fiber: the conclusion shows that the surface of PP fiber is grafted silane, and thanks to the decomposed function of TBPO, at the same time PP fiber's surface appears some slight snicks, which is in favor of increasing the degree of coarseness of fiber's surface. The best disposed condition is showed as follow: the content of silane is 30 percent, the content of TBPO is 0.5 percent, the reacted temperature is 50 centigrade, the disposed time is 20 minutes, the marinated time is 3 hours, the poached time is 1 hour.(2) Grafting acrylic acid onto PP fiber initiated by KMnO4/ H2SO4: the test shows that such reactive functional groups as–COOH are introduced onto the surface of PP fiber, and the system of KMnO4/ H2SO4 has high oxidation, which increases the degree of coarseness of fiber's surface. The best disposed condition is showed as follow: the concentration of acrylic acid is 0.8mol/L, the disposed time is 3 hours, the concentration of H2SO4 is 0.2mol/L, the concentration of KMnO4 is commanded 5×10 ? 3mol/L, pretreatment time is 30 minutes, pre-initiated time is 30 minutes.