| The excellent performance of Ultra-high molecular weight polyethylene (UHMWPE) is benifited by its high molecular weight, which is up to 10~7. UHMWPE is used of parts for wear resistance, due to higher abrasive resistance. UHMWEP is wildly used in the medical field as totle knee and hip joint replacement prostheses for approximately three decades, which is result in the properties of nontoxic. UHMWPE is excellent in impact strength and with lower density, for which UHMWPE is wildly used for manufacture. This study is focus on the relationship between internal structure and performance of UHMWPE. The conclusion of this study is applied for more efficient in manufacturing UHMWPE by compression moulded.There are two parts of this study:firstly, analysis of the effect of process on crystallinnity and wear of compression moulded UHMWPE; secondly, analysis of the effect of process on microstructure and ceofficient of linear thermal expension of compression moulded UHMWPE. The main content of this study is as follows:1. Crystallinity and wear of UHMWPE are benifited from the middle level of compression moulding temperature and time. There are approximately the same tendency between Crystallinity and wear, with processing of heating compression moulding changed. Heating compression moulding processing to achieve the best wear of the sample are:compression moulding temperature of 230 ℃ and compression moulding time of 30min.2. Decreasing cooling rate, or to carry out soaking time at temperature of crystallinity, wear of UHMWPE is increased with crystallinity. Cooling cycle to obtain the best wear of the sample is: cooling with heating compression moulding machine and soaking at the temperature of crystallinity for 30min.3. Coefficient of linear termal expension is decreased with cooling compression moulding pressure increased, and the average size of crystallite is fluctuation changed. UHMWPE owned the smallest average size of crystallite and the minimum coefficient of linear thermal expension, with cooling compression moulding pressure of lOMpa. With the same crystallinity of the sample, the tie moleculars are increased with the average size of crystallite decreased. The increased tie moleculars enhance the interaction force between lanellas, which will decrease the coefficient of linear thermal expension.4. Cooling cycles gradually changed from non-cooling water to full-course cooling water, coefficient of linear thermal expension inceased first and then decreased. The average size of crystallite is fluctuation changed with the cooling cycle changed. With the same crystallinity, the coefficient of linear thermal expension is decreased with the average size of crystallite decrased. |
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