The less common families of engineering polymers, like ionomer resins, tend not to register at the forefront of designers’ minds, probably because they have performance characteristics that are best suited to very specific product requirements. But what’s important to me as a designer is that, although it would be simpler if you could categorize the properties of materials based on their product applications, there are some plastics that have applications and formulations that are so diverse it is difficult to characterize them in a straightforward way. Ionomers falls into this category, with Surlyn®, one of the big engineering polymer brands from Dupont, being one of the most recognized ionomer brands.
Essentially, this polymer can be summarized as having outstanding impact strength, even at low temperatures; scuff, abrasion and chemical resistance, with extremely high optical clarity, which, combined with its mouldablilty, means it can be more versatile than glass for transparent products.
However this material, which has numerous high-performance and ‘special’ characteristics, can be marketed in a way that gets designers to find new applications for its many properties. Ionomers appear in many varied forms, they are used for their crystal clear clarity in the injection-moulded walls of perfume bottles, for squeezable, soft extruded shampoo tubes, and even in the tough, resilient material of a dog chew.
Image: Golf balls
Key features
•Outstanding impact toughness
•Abrasion resistant
•Scuff resistance
•Good chemical resistance
•High clarity
•High melt strength
•Recyclable
Cost
£2 ($3) per kg.
Sustainability issues
Petroleum-based, so not sustainable long term, but can be recycled. Also being used to make lighter packaging materials.
Production
Ionomers can be injection moulded, extruded, foamed, thermoformed or used as a powder-coating or resin modifier to give extra strength to other polymers. They also offer direct adhesion to metal, glass and natural fibres through heat lamination.
Typical applications
Because of their strong impact resistance, ionomers lend themselves to a range of abusive environments, such as the end of a tool handle that gets hit with a hammer or in the ten-pin bowling lane for the pins. It is also used as a material for dog chews, an equally gruelling and robust application. One of my favourite applications is in golf balls. Apart from these extreme cases, ionomers do have a softer side and, with their excellent chemical resistance and clarity, they make ideal glass and crystal replacements for perfume bottles. In film form, ionomers are used in a range of food packaging including fresh meat and fish, which exploit its toughness. Other applications include hockey helmets, footwear, body boards, tool handles, glass coating, ski boots, automotive fascias, perfume caps and bath and kitchen door handles.
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–Extremely tough and resilient –Good chemical resistance –Versatile –Widely available –Recyclable |
–Petroleum-based so not the most sustainable option |