Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene for Ultimate Tensile Properties

Ultra-High Molecular Weight PolyEthylene (UHMWPE) is known to be an engineering material rather than a commodity plastic due to its excellent mechanical properties together with the chemical and high abrasion resistance. The main drawback of this material is the processability due to the very high viscosity of the melt due to the large number of entanglements. Recently, a significant improvement in the processability has been reported. The fundamental concept is to reduce the formation of entanglements in the amorphous phase of the semi-crystalline polymer by fast crystallizing the growing chains during polymerization. The so-called disentangled UHMWPE can be processed in the nascent powder into high modulus/ high strength tapes [1]. Several catalytic systems are known to produce polyethylene, but few are reported to have ultra-high molecular weight capabilities, even fewer to produce disentangled UHMWPE. In the present study we have investigated the effect of some reaction conditions in the polymerization of ethylene using a bis(phenoxyimine) Titanium (IV) catalyst capable to synthesize disentangled UHMWPE. The polymers produced are characterized by rheology, DSC and SEM. The polymers synthesized can be solid state processed into uniaxially drawn tapes having high modulus/high strength making them suitable for extreme performance applications (Figure 1) [2]