Rotational moulding of polyethylene foam became an important process in various industries. Demand for rotomoulded foam has been increased due to its thicker walls, low sound transfer, high stiffness and good thermal insulation. However, prior production, polymer testing labs make it necessary to assess the rotomouldability of foamed polyethylene material. This is important for the evaluation of its behavior in the rotational moulding process and the final product quality. To obtain this assessment, Melt flow properties are often checked by testing the specimen. This critical test procedure can be conducted using an accurate Melt flow index tester which complies with the standard of ASTM D 1238.

Polyethylene foam and its uses

Polyethylene is a closed-cell foam and is constituted of millions of tiny bubbles, sealed off from each other. This type of construction provides a water resistance system along with strength and rigidity. It is also resistant to solvents, petroleum products, and is antimicrobial. Anti-static features of the foam allow it to deliver best quality packaging, handling, and transportation used for delicate electronics, by dissolving electro-static charges that can build and damage components. They are often utilized in casing and custom packaging as it can be easily cut to create form-fit inserts for securely moving or transporting items.

The foam insulation offered by polyethylene resists moisture and heat. The sheets formed by them are easily laminated together to create thicker sections that can then be cut for personal flotation.

The Melt flow indexing process

Melt flow index of the Polyethylene foam mixer is conducted using Melt flow index tester as per the standards of ASTM D 1238. It is the output rate (flow) of the polymer sample in grams that occurs in 10 minutes of time through a standard die at a fixed pressure applied via a piston and a load.

It is an assessment of average molecular mass and is an inverse measure of the melt viscosity; in other words, the higher an MFI, the more polymer flows under test conditions. Knowing the MFI of a polymer is vital for anticipating and controlling its processing, the polyethylene foam material are tested for its melt flow properties. During the test, the MFI value increases as the foam percentage increase up to 6% after which the value decreases. Therefore it is concluded that 6% of foam is the optimum level to obtain easy processing during rotational moulding and will yield better product quality.

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