Study On The Effect Of Particles On Ultra High Molecular Weight Polyethylene Fiber Reinforced UD Plate

Ultra high molecular weight polyethylene (UHMWPE) fiber possesses special structure which gives it the ability of high energy absorption. Therefore, unidirectional (UD) plate made of UHMWPE fiber and adhesive is widely used in ballistic protection such as bullet proof vests and helmets. However, the comprehensive property of UD plate remains an issue due to the lower strength of adhesive and serious creep behavior of UHMWPE fiber as well as relatively low mechanical properties. A number of researchers have been directed to solve the problem by modifying UHMWPE fiber, such as plasma treatment, chemical oxidization, cross-linking modification and so on. However, these methods could only improve the performance of heat-resistance to a certain extent, and the mechanical properties of the fiber decreased at the same time. In this paper, the ballistic performance of UD plate and creep behavior of UHMWPE fiber with the addition of modified conch powder and carbon nanotubes (CNTs) were studiedThe main research contents and conclusions are as follows.The characteristic and surface modification results of conch powder were studied. The special cross-laminated microstructure was found. The ingredient of conch was calcium carbonate and small percentage of organic which was verified by the methods of elementary analysis, XRD and TGA. The suitable processing temperature for conch powder was also studied. The condition of dispersibility and compatibility of conch powder with matrix was important for mechanical toughing. Conch contains little organic and displays polarity of surface. Therefore, it is necessary to take surface modification and decrease the surface energy of conch powder. The titanate coupling agent was selected as modifier. In order to investigate the influence of coupling agent content, reaction temperature and time to the effects of surface modification, orthogonal test was used. The hydrophilicity and surface energy were tested by static state contact angle. The optimized process of surface modification was chose combined with FT-IR results. The most important influence factor for surface modification of conch powder was coupling agent content.Polyethylene (PE) was selected in this paper as the matrix of UD plate because of same structure with UHMWPE fiber. Modified conch powder was added into polyethylene in hope of toughing the matrix. The influence of conch powder content, coupling agent content and particle size of conch powder to the comprehensive property of polyethylene composites were studied separately. The results showed that it did not promote the crystallize of polyethylene. However, it reduced the crystallinity of polyethylene composites. The impact and tensile tests were carried out on the PE composites with different conch powder contents. It proved that the impact strength was improved by adding conch powder in PE. But the tensile strength was decreased. The conch powder modified by different coupling agent content was compounded with PE. Subsequently, the impact and tensile tests were carried out and found the best coupling agent content. Four different sizes of conch powder were chose to add in PE. And we can found the best particle size of conch powder from the impact strength. To contrast the mechanical properties of PE/conch powder with PE/CaCO3 composite, it showed that the toughing effect of conch powder was not because of the ingredient but the special organic-inorganic cross-laminated structure.It wasn’t accurate to analyze the dispersion state of conch powder in matrix sometime. Therefore, the fractal theory was used in this paper to discuss the dispersion of conch powder in matrix. PE/conch powder composites with different conch powder content were made first. Then the SEM pictures were handled by modeling. The fractal dimension of PE/conch powder composites with different conch powder contents was calculated. So we can describe the dispersion of conch powder exactly. Afterwards, the influence of conch powder dispersion condition to the impact strength of PE composite was analyzed. The toughing mechanism of conch powder in PE matrix was discussed at last.UHMWPE/CNTs composite fiber with different carbon nanotube (CNT) was made by gel spinning. Different test apparatus were used to characterize the morphology and structure, crystallization behavior, heat resistance and mechanical properties of the composite fiber. The creep rate for 1h of each composite fiber sample under a series of constant stress was also tested. The result showed that the creep property was improved when CNTs were added to UHMWPE fiber. Changes in creep rates of composite fiber tend to slow when the amount of CNTs was increased. Dimensional stability of the composite fiber was highly enhanced.The modified UD plate was made by adding surface modified conch powder to adhesive matrix and using UHMWPE/CNTs composites fiber instead of UHMWPE fiber as reinforcement. The influence of dispersion state of conch powder in UD plate and the manufacture process to the ballistic proof property were studied. The ballistic tests were carried out with different samples according to GA141-2001 standard. The results showed that the bulletproof and impact resistant performance were improved by adding conch powder in adhesive. It showed upstanding bulletproof ability at high and low temperature. This proved that the heat resistant property of UHMWPE fiber was improved by using CNT. The life time for UHMWPE/CNTs fiber reinforced PE/conch UD plate could be gratly extended.