Polyethylene rotational molding

Polyethylene rotational molding can use either linear low-density polyethylene (LLDPE) or high-density polyethylene (HDPE) to produce strong, hollow parts for indoor and outdoor applications. LLDPE and HDPE are similar in terms of chemical composition but have some important differences when it comes to performance properties.

How are LLDPE and HDPE rotationally molded?

LLDPE and HDPE use the same basic process during rotational molding. First, powdered plastic or plastic pellets are added to a metal mold. Next, the tool is rotated and heated so that the polyethylene softens to the point that it begins to coat the inside of the mold. While rotating, the tool is then cooled so that the plastic solidifies. Finally, the mold is opened and the rotomolded part is removed.

What are the advantages of LLDPE?

LLDPE has medium stiffness and high tensile strength, the maximum stress a material can withstand while being pulled or stretched before breaking. This polymer is durable but forgiving, and virgin LLDPE provides resistance to chemicals and environmental stress cracking. For outdoor applications, LLDPE can be enhanced with UV stabilizers and with anti-fungal or anti-microbial additives.

What are some applications for LLDPE?

Applications for rotomolded LLDPE include plastic tanks, buckets, bins, containers, toys, and outdoor recreational products and equipment. Because LLDPE can be blended with pigments, designers can achieve specific colors without parts painting.