Surface Modification Of Polypropylene And The Study Of Application Property Of PP Fiber Reinforced Cement Composite Material

Polypropylene (PP) is an important chemical raw material. It has many excellent properties, such as chemical stability, acid/ alkali-resisting, high wet strength, high percentage elongation, low density, easily available and low price. When PP fiber is combined with cement, it can improve the toughness, impact strength and other physical properties as well as the use value and durability of cement material. So it has been widely used in making fiber reinforced cement composite material (FRCC).In this study, corona discharge treatment has been used to prepare surface modified PP. The influence of different treatment power and time has been investigated. Then the poor hydrophilicity and adhesion property between PP fiber and cement material can be improved. Here we suggest a new method to stabilize the hydrophile groups by surface crosslinking. Then the modified PP fiber was used to prepare FRCC material. The interfacial property and crack-resisting of FRCC are also studied.The relationship between surface structure/composition percentage and the experimental parameters were investigated by XPS. The percentages of introduced oxygen groups were analyzed quantitatively. The variation of the two competitory reactions, introducing and etching of the oxygen groups, was investigated systemically. The surface hydrophilicity of modified PP was observed by means of contact angle testing. The influence degree of different parameters, such as treatment power and time, on the property was systemically analyzed. The decay rule of hydrophilicity under room temperature was also observed by XPS and contact angle testing. It was found that there is an optimum value for power and time. When exposed in air, the increment of contact angle of surface crosslinking treated material is lower than that of without crosslinking. It indicates that the transfer ofpolarity groups was restrained greatly.The modified PP fiber was used to make FRCC material. The influence of PP fiber on physical properties of as-made material, such as interfacial adhesion property and plastic shrinkage cracking, was investigated. The experiments show that the critical pull out length is shorter and the pull out strength is higher of modified fiber than that of without modified. These indicate that the adhesion property was improved. The crack morphology shows the shrinkage cracking can be restrained markedly and the crack width was also narrowed. The results show that the properties of FRCC material have been improved compared with cement without fiber. So it may have potential use and is feasible.