In conducting the research on Material Science two composite materials ultra high molecular weight polyethylene (UHMWPE) powder and aluminum oxide (Al2O3) powder were formulated by hot compression molding process. The formulated materials demonstrated good mechanical properties and high wear resistance properties. Based on the studies the Al2O3 grade selected was Al2O3 HTM 30 harboring mixed uneven powder particle sizes ranging from 2 to 5 microns (μm) and selected proportion of Al2O3 alloy mixed for improving mechanical and wear resistance properties of the UHMWPE composite material was the UHMWPE+Al2O3 HTM 30 at a ratio of 95:5%. When considering both material properties and cost effectiveness in the impact test 2-5 μm Al2O3 HTM carried the higher impact strength than other aluminum oxide grades with the values up to 586.8 J/m at a ratio of 5% aluminum oxide. The hardness test of the 2-5 μm UHMWPE+ Al2O3 HTM delivered the hardness at 58.8 using the standard durometer. The tensile test values consisted of Yield Strength Ultimate Tensile Strength Breaking Strength Elongation at Break and Modulus of elasticity equal to 20.52 MPa 29.96 MPa 22.83 MPa 265.8% and 784.46 MPa respectively.

This research presents a study about extrudate swell properties of high density polyethylene melts in annular die extruded in a capillary rheometer through 3 types of annular die: normal annular die convergent annular die and divergent annular die. Each type of die had a die gap of 1mm 1.5 mm and 2 mm respectively. Results of the experiment showed that extrudate swell of high density polyethylene melts occurred in both diameter swell and thickness swell ratio. The swell measured in all 3 types of die tended to be higher with the increase of shear rate and the decrease of 2 mm 1.5 mm to 1 mm die gap by an average of 12%. This occurrence could be explained from measurement of flow properties in all 3 types of die which had increasing shear stress due to the decrease of die gap by an average of 10%. Moreover it was also found that the thickness swell ratio was higher than the diameter swell by an average of 45% in all sizes of die gap. This could be explained from the Stress distribution which was more dense at the mandrels surface when the die gap of annular die decreased.

The objective of this research is a study to determine optimum forming condition of semi-finished bulk UHMWPE by using ram extruder that obtain maximum yield strength and minimum wear rate for apply to use in area of medical and mechanical application. Experimental extrusion specified forming condition consists of the temperature of 140 150 and 160 ºC and pressure of 3 5 8 and 10 MPa with the temperature exposure time of 30 minutes. After known optimum forming condition of UHMWPE powder thus forming UHMWPE filled with different kind of filler to study and determine optimum weight fraction of various types of filler that affect onto wear resistance property of UHMWPE composites. Result extruded condition at the temperature of 1 5 0 ºC under pressure of 5 MPa with exposure time of 30 minutes is an optimum extruded condition due to specimen shown a maximum yield strength ultimate tensile strength and elongation of 20.43 ± 1.21 MPa 28.33 ± 1.53 MPa and 285.60 ± 6.41 % respectively and obtain minimum wear rate of 3.02  10-9 ± 5.27  10-10 mm3/Nm. Its mechanical properties and wear resistance property higher than imported bulk UHMWPE by 23.3 % and 4.75 times respectively due to the formation of cross-linking are occurred in polymer chain and also its degree of crystallinity is high equal to 61.52%. For bulk UHMWPE IR-spectrum shown a variation peak of carbonyl group (C=O) are occurred that that it indicated the oxidation reaction at the end of polymer chain and tis degree of crystallinity is equal to 53.31% which result to decrease strength of polymer. In the case of UHMWPE filled with filler optimum weight fractions of various types of filler are as follows. 1. The filling of 0.3 wt. % Al2O3 particle size 0.05 μm shown yield strength ultimate tensile strength and elongation of 23.17 ± 3.35 MPa 34.78 ± 2.80 MPa and 229.00 ± 6.09% respectively that its mechanical properties was increased by 18.55% (increasing of ultimate tensile strength). For the wear rate is equal to 2.09  10-9 ± 3.39  10-10 mm3/Nm or its wear resistance was increased by 1.44 times in compared with initial bulk UHMWPE. 2. The filling of 0.4 wt. % Al2O3 particle size 0.3 μm shown yield strength ultimate tensile strength and elongation of 21.93 ± 0.51 MPa 25.40 ± 0.69 MPa and 267.67 ± 22.03% respectively that its mechanical properties was increased by 11.54% (increasing of ultimate tensile strength). For the wear rate is equal to 2.32  10-9 ± 4.78  10-10 mm3/Nm or its wear resistance was increased by 1.30 times in compared with initial bulk UHMWPE. ฉ 3 . The filling of 0.4 wt. % Al2O3 particle size 1 μm shown yield strength ultimate tensile strength and elongation of 23.93 ± 1.89 MPa 26.77 ± 1.20 MPa and 296.54 ± 7.51% respectively that its mechanical properties was increased by 5.83% (increasing of ultimate tensile strength). For the wear rate is equal to 2.14  10-9 ± 3.16  10-10 mm3/Nm or its wear resistance was increased by 1.41 times in compared with initial bulk UHMWPE 4 . The filling of 4 wt. % Al2O3 particle size 5 μm shown yield strength ultimate tensile strength and elongation of 22.57 ± 2.01 MPa 26.31 ± 3.11 MPa and 136.66 ± 11.67% respectively that its mechanical properties was increased by 7.68% (increasing of ultimate tensile strength). For the wear rate is equal to 2.37  10-9 ± 5.71  10-10 mm3/Nm or its wear resistance was increased by 1.27 times in compared with initial bulk UHMWPE