High-density polyethylene surface properties

Surface fluorination changes the polymer surface drastically, the most commercially significant use of polymer surface direct fluorination is the creation of barriers against hydrocarbon permeation. The effectiveness of such barriers is enormous, with reductions in permeation rates of two orders of magnitude. Applications that exploit the enhanced barrier properties of surface-fluorinated polymers include (1) Polymer containers, e.g., gas tanks in cars and trucks, which are produced mostly from high-density polyethylene, where surface fluorination is used to decrease the permeation of fuel to the atmosphere and perfume bottles. (2) Polymeric membranes, to improve selectivity commercial production of surface-fluorinated membranes has already started.13... 

Polyethylene is a widely used, inexpensive, and versatile polymer due to its abundant supply, good chemical resistance, good process ability, and low-energy demand for processing. Polyethylene exists in low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE) forms. HDPE has very poor adhesion properties to other materials because of PE s low surface... 

N. M. Stark and L. M. Matuana, Surface chemistry and mechanical property changes of wood-flour/high-density-polyethylene composites after accelerated weathering. J. Appl. Polym. Sci. 94, 2263-2273 (2004). 

Arkema s Kynar Flex PPA 5300 is another fluorinated polymer processing aid, available in granular form. This product is targeted at linear low-density and high-density polyethylene and metallocene PE grades. It eliminates orange peel surfaces and improves the transparency and mechanical properties of the extruded product. It also increases extrusion speed, eliminating knots and drool in the extrusion dies. 

Kevlar fibers can be used as reinforcement for wood-flour/high-density-polyethylene matrices to improve their mechanical properties. The study of Ou et al. [112] demonstrates that the addition of a small amount (23%) of Kevlar short fibers can cause an improvement in the tensile, flexural and impact properties of HDPE/wood composites. As expected, additional surface modification of the Kevlar fiber with organosilanes and halides resulted in a further improvement on the composites mechanical properties. This effect was ascribed to the increased interfacial compatibility between the aramid fibers and HDPE, evidenced by SEM, XPS and FTIR methods. 

Pourabas and Peyghambardoost [70] prepared positive temperature coefficient composites by using metal-modified and unmodified carbon black in a matrix of high-density polyethylene. Modification with metallic particles led to properties that were related to changing the surface properties of the carbon black. The intrinsic electrical conduction of carbon black also changed after modification. These changes in properties endowed some desirable characteristics to the positive temperature coefficients. 

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