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2017-09-20Author
Chartpuk, Prakorb
Tempiam, Anan
Wanasri, Surat
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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.
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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
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- Research Report [286]