An investigation into the production of UHMWPE fibres and coatings for protective apparel

Abstract

The primary aim of this research was to identify a novel process for the manufacturing of UHMWPE fibres and coating. Due to the high molecular weight of UHMWPE, it cannot be converted into fibres by standard extrusion processes it must be firstly dissolved in hydrocarbon solvents such as decalin, kerosene etc, which are unsustainable and potential hazards (to environment and human), then extruded to form a gel fibre. Following the extrusion process the solvent must be removed which involves the use of a secondary solvent e.g. n-hexane, toluene etc. which themselves are potentially hazardous. Research revealed that terpene, a waste product of the orange juice industry was suitable substitute for the currently used solvents. Gel produced as a mixture of UHMWPE and terpene was successfully converted into fibres and fabric coatings. However, the ram process was initially found to be problematic, which was due to the presence of entanglement of the polymer chains. This was resolved by applying acoustic energy to the gel, which optimised the chain alignments thus reducing entanglement and allowing a consistent fibre to be ram extruded. The terpene based extrusion process designed in this research eliminated the solvent removal stage, which eliminated the use of secondary solvent thus eliminating the hazards and cost associated with it. Since the process does not involve a separate solvent removal stage, it has the potential of reducing the processing cost. The terpene also allowed a consistent UHMWPE coating to be applied to the cotton fabric. The coated fabrics showed a good resistance to highly concentrated acids, indicating the potential application of such coatings as protective apparel in the areas involving concentrated acid e.g. liquid acid battery, fertilizer industry, iron and steel making industries where acids are widely used. The coating process developed in this research has expanded the use of UHMWPE beyond the current possibilities.