UHMWPE is a linear structure, but because of its large molecular weight, it is difficult to crystallize, and it is a low-crystallization product with a relative density of 0.94. Compared with ordinary PE, UHMWPE has better wear resistance (15 times larger than POM), low friction (friction coefficient of oil lubrication is 0.05 ~ 0.08), good impact resistance, excellent impact absorption, high repeated fatigue strength, light weight, good electrical insulation, good self-lubrication, low temperature resistance (-169~90℃), good physiological compatibility (used in medicine) and corrosion resistance, etc. It is called “amazing” engineering plastics. However, UHMWPE also has some shortcomings, such as low hardness, low strength, poor heat resistance, difficult processing and poor creep resistance. The specific performance of UHMWPE is as in the table below.
| Performance Comparison Between UHMWPE and HDPE | |||
| Performance | UHMWPE | HDPE | |
| Relative Density | 0.939 | 0.945 | |
| Transparency | Opaque | Translucent ~ Opaque | |
| Water Absorption / % | <0.01 | <0.01 | |
| Melt flow Index / （g/10min） | 0 | 0.2~8 | |
| Molding Shrinkage Rate / % | 2~3 | 2~5 | |
| Tensile Strength / MPa | 30~50 | 21～37 | |
| Rockwell Hardness | R38 | R35 | |
| Notched Iimpact Strength/(kJ/ m2) | >100 | 40~70 | |
| Heat Deflection Temperature /℃ | 95 | 78 | |
| Brittle Temperature /℃ | <-137 | -140~- 100 | |
| Melting Point/℃ | 135~137 | 131～137 | |
| Resistance To Environmental Stress Cracking/h | >4000 | 2000 | |
The wear resistance of UHMWPE is the crown of all kinds of pure plastics, and the larger its molecular weight is, the higher the wear resistance is. The comparison of wear resistance of UHMWPE and other materials is as in the following table. When UHMWPE is paired with steel and copper, adhesive wear is easy to occur, and the wear to the mating parts is small.
UHMWPE has good self-lubrication, and its rolling friction coefficient is the lowest in plastics. When there is no lubrication, the friction coefficient is 0.04 ~ 0.11, and when there is oil lubrication, the friction coefficient is 0.05~0.08, this is because of its good self-lubrication.
UHMWPE can work in the form of sliding or rotating without lubrication, and lubricate better than steel and copper in the case of lubricating oil.
UHMWPE has a strong ability to absorb impact and friction and silence, and has the advantage of low friction noise.
The impact strength of UHMWPE ranks first among all kinds of plastics, and it is the most impact-resistant variety among the existing plastic varieties. The impact strength at room temperature is comparable to that of polycarbonate (PC), which is well known for its impact resistance, and the impact performance at low temperature is even better than polycarbonate. Its impact strength is 10 times that of PA66, 20 times that of PVC, 5 times that of PE100, 8 times that of ABS, 22 times that of POM, and 25 times that of PBT.
UHMWPE has good fatigue resistance, and the fatigue resistance is greater than 500,000 times, which is 30 times that of PE100.
UHMWPE has a very large molecular weight, but very few unsaturated bonds, so it has excellent chemical corrosion resistance, and can resist various corrosive media such as acids, alkalis, salts, and various organic solvents. UHMWPE has good radiation resistance.
UHMWPE has good environmental stress cracking resistance, and the stress cracking resistance time is as high as 4000h, which is more than twice that of PE100. UHMWPE has good high temperature creep resistance.
Although the heat resistance of UHMWPE is not high, the heat distortion temperature is 90℃, and the service temperature is 100~110℃, its low temperature resistance is very good, which can be as low as -169℃. It has the lowest temperature resistance among all the plastics, and its low temperature impact is very good. The linear expansion coefficient of UHMWPE is( 1.5～2.5)×10-4K–1, and the thermal conductivity is 8.5W/(m·K).
The volume resistivity of UHMWPE is greater than1015Ω·cm, the dielectric strength is 90kV/mm, and the dielectric constant is 2.3. UHMWPE has no adsorption on the surface and no adhesion to any material.
