Rotational Molding and the Importance of Impact Toughness (And Temperature!)
NYCOA Topics in Engineered Plastics: Rotational Molding and the Importance of Impact Toughness
Nylons are used in various specialty applications in the rotational molding (rotomolding) industry because of their desirable properties for engineering applications. Nylon-6 (PA-6) is the most common polyamide used in the rotomolding market because it is widely available and provides a price competitive solution to other engineering polymers without compromising on performance. PA-6 provides excellent fuel barrier properties, high modulus and tensile properties, phenomenal chemical resistance, and high performance at elevated temperatures. This has led to PA-6’s wide use for rotomolded products such as gasoline/diesel tanks, chemical storage systems, and hydrogen fuel cells.
Across the numerous applications for nylon in rotomolding, impact toughness across a wide temperature range is one of the key performance requirements. The Association of Rotational Molders (ARM) has established an impact testing method where a dart of a specific weight is dropped from various heights onto rotomolded plaques of a known thickness (usually 1/8 inch thick). This test method was originally developed to test the impact toughness of a resin at low temperatures (-40 °C) but can also be used to test a resin at room temperature. The same stiffness and high temperature performance of traditional PA-6 lead to brittle failure on impact, causing it to shatter like glass. NYCOA has developed a solution to this problem in the form of NYCOA 1702: a rotomolding grade of PA-6 that uses proprietary modifications to provide a room temperature impact toughness that suits a variety of challenging applications, such as external fuel tanks used in agricultural and automotive applications. NYCOA 1702 has also been designed to reduce the cycle time required to mold parts, improving further on the economic advantages that come with PA-6. NYCOA 1702 is available as a powder (20 mesh) or as standard pellets and can be provided in off-white or black color.
Unfortunately, PA-6 does not provide a suitable solution for products that need the high performance of a nylon at low temperatures. This problem is often addressed by molding a multilayer product with a more flexible polymer, such as crosslinked polyethylene (XLPE), making up the outside of the product and PA-6 forming an internal layer. While this resolves the need to meet impact requirements, but it presents a variety of undesirable side effects including increased cycle times, more complex processing methods, higher part weight, and a thicker part wall. NYCOA has approached this challenge from a new direction by using our NYFLEX® CT-155 E TPE to provide the chemical resilience associated with nylons while providing unmatched low temperature impact toughness. NYFLEX® CT-155 is available as a powder (20 mesh) or as standard pellets and can be provided in off-white or black color.
About NYCOA
NYCOA (the Nylon Corporation of America) commercially manufactures many grades of nylon, including NXTamid, a unique long-chain polyamide alternative to nylon 11 and nylon 12. NYCOA has also developed the custom flexible PEBA NY-FLEX, which has shown excellent processability and cold temperature impact strength in rotational molding applications.
All NYCOA products are made in the USA, manufactured in our ISO certified plant located in Manchester, NH. NYCOA is dedicated to plastics engineering, plastics innovation, and a consistent quality earned through operational excellence. NYCOA is dedicated to its customers, and produces specialty engineered polymers for industries and partners around the world, and has plastics compounding capabilities to produce a variety of reinforced and modified grades.
NYCOA manufactures specialty engineered polyamide (nylon) plastics for many industries and applications, including fasteners, hook and loop, extruded parts, injection molding, foamed components, monofilament, powders, and wire and cable jacketing.
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