Enhancing Natural Rubber Tearing Strength by Mixing Ultra-High Molecular Weight Polyethylene Short Fibers

Area of Science:

• Materials Science
• Polymer Science
• Mechanical Engineering

Background:

• Rubber products require high resistance to mechanical stresses like abrasion, tear, and cutting.
• Incorporating reinforcing short fibers into a rubber matrix is a viable strategy to enhance mechanical properties.
• Ultra-high molecular weight polyethylene (UHMWPE) possesses strong mechanical properties suitable for reinforcement.

Purpose of the Study:

• To investigate the effect of UHMWPE short fibers on the tear strength of natural rubber (NR) composites.
• To determine the influence of fiber content and vulcanization conditions on the mechanical properties of NR/UHMWPE composites.
• To explore the potential application of these composites in industrial rubber products, such as conveyor belts.

Main Methods:

• Incorporation of UHMWPE short fibers (20 μm diameter, 2 cm length) into a natural rubber matrix.
• Investigation of varying short fiber mass fractions and vulcanization parameters (temperature, time).
• Mechanical property testing (tear strength) and Scanning Electron Microscopy (SEM) for microstructural analysis.
• Control experiment using UHMWPE resin powder instead of short fibers.

Main Results:

• Optimized double-roll milling and vulcanization at 143 °C for 40 min yielded strong interfacial adhesion between UHMWPE fibers and NR.
• Addition of 2 phr UHMWPE fiber increased tear strength by 150.2% (from 17.1 kN/m to 42.8 kN/m).
• SEM confirmed homogeneous dispersion of UHMWPE fibers and a compact fiber-matrix interface.
• UHMWPE resin powder showed minimal improvement in mechanical strength compared to NR.

Conclusions:

• Milling process and vulcanization conditions are critical for enhancing the tear resistance of NR/UHMWPE composites.
• UHMWPE short fibers significantly improve the tear strength and overall performance of natural rubber.
• The developed composite offers a promising, surface-modification-free approach for improving tear resistance in industrial rubber products like conveyor belts.