No abstract

Polyethylene materials are the most widely used polymers which we encountered everywhere in our daily life. Some of the advantages of the polyethylenes are the diversity of production types, corrosion resistance, electrical insulation and recyclability. The main production methods are compression molding, transfer molding, rotational molding, injection molding, gas-assisted injection molding, extrusion and blown film extrusion techniques. It is possible to increase the mechanical properties of low density polyethylene materials by addition of high density polyethylene materials. Both polymer has same monomers but their chemical structure and bonding properties are different. Their physical properties can change with their chemical structure and bonding properties. In this study, 25%, 50% and 75% by weight of high density polyethylene were added to low density polyethylene. Granules were pre-mixed with a mechanical mixer before production of the samples. Plastic injection molding machine was used for specimen preparation. Density, hardness, tensile test, three-point bend test, compression test, tear test and Izod impact tests were performed. Densities and hardness values of the polymer blends decrease by the increasing amount of low density polyethylene. In general, it was observed that the mechanical properties of the polymer blends increase as the high density polyethylene content increase.

Polymeric materials find usage in most places in daily life. Expected features vary depending on the use of these materials. Composite material can be formed by combining one or more different materials. Physical and chemical properties of a new produced composite material can be improved with the addition of additives and fillers to polymer materials. The addition of additives and fillers improve one or more properties at the same time, despite that, it may lead to deteriorate another property. Therefore, it is necessary to investigate the mechanical and thermal properties of these produced composite structures. This study was carried out by nanoclay addition to high density polyethylene (HDPE) and polypropylene (PP) materials. Nanoclay additions were made to the polymer matrix at mass ratios of 5% and 10%. Tensile test, tear test and the Izod impact tests were performed. It has been observed that the tensile strengths of HDPE composites decreased whereas PP composites increased with respect to the pure products. Also, the tear strengths of composites decreased compared to pure products. In the Izod impact tests, all notched specimens were broken. The values of impact strength of the PP composites were not changed in the notched Izod impact tests, whereas the HDPE composites showed a decrease.

In this work, ammonium polyphosphate and melamine were added as a flame retardant to the nanoclay reinforced high-density polyethylene composites. Ammonium polyphosphate and melamine were added at weight ratios of 0 wt% and 20 wt% to the polymer matrix and their proportions are changed. The addition of nanoclay was carried out at weight ratios of 2 wt% to the polymer matrix. Blending operations were performed by premixing with a mechanical stirrer and melt extrusion technique with twin screw extrusion, respectively. The samples were produced by injection molding. Tensile tests, three-point bend tests, tear tests, the Izod impact tests, and thermomechanical analysis were carried out to investigate the mechanical and thermal expansion properties. Mechanical and thermomechanical test results showed that addition of intumescent flame retardant systems and nanoclay decrease the tensile strength and coefficient of linear thermal expansion values while increasing flexural strengths slightly. However, it has been observed that the addition of additives increases the flexural modulus and density of the polymer composites.