Current Applied Polymer Science - Volume 8, Issue 1, 2025

Hemp and other natural fibers are seeing greater use in industry due to their useful mechanical properties and sustainability. Natural fibers can reinforce or fill polymers to reduce cost and increase biodegradability. Ultra-high molecular weight polyethylene (UHMWPE) exhibits exceptional toughness and is capable of being mixed with natural fibers.

In this study, hemp fiber, in powder form, has been blended with UHMWPE powder and processed by compression molding to evaluate mechanical strength properties. The effects of adding low molecular weight polyethylene wax (PE-wax), a property modifier, were also examined. The hemp content of the compositions was 0, 20, 40, 60% w/w, with and without the wax.

Consistent with filler behavior, the addition of hemp significantly reduces the ultimate and yield tensile strengths as well as the elongation at break; the effect increases with more hemp. PE-wax improves performance at 40% and 60% w/w hemp, compared to the no wax condition. The presence of hemp increases the elastic modulus for 20% and 40% w/w hemp, and PE-wax improves the elastic modulus at all hemp concentrations. Compressive strength declines as hemp content increases, and the wax raises the performance at all hemp levels, nearly doubling the 20% w/w hemp strength. Shore type D hardness values steadily decline with hemp content, with a 60% loss in hardness, from the pure UHMWPE baseline to the 60% w/w hemp sample.

The simplified process outlined in this study produced materials that are fit for use in engineered applications. The process was also much simpler than traditional hand lay-up techniques, making it attractive for use in industrial applications.