UV-durable composites

August 19, 2016

Outdoor elements – sunlight in particular – aren’t kind to the materials used in polyester composites. Polyester, vinyl ester and other resins break down when exposed to ultraviolet light over extended periods. Air and humidity take their toll as well, as materials oxidize and/or hydrolyze over time.

Fiber-reinforced composites have inherent limitations but are tough, strong, cost effective and potentially durable for use in a wide range of outdoor applications, leading innovators to develop ways to increase a material’s endurance when exposed to outdoor elements.

Improving weatherability performance
There are limits to what can be done regarding replacing resins with more UV-durable materials. However, there are ways to protect resins and other composite components from sunlight and moisture, and that’s where colorants and additives come in.

Synergies between colorants and additives can help prevent sunlight from reaching and destroying light-sensitive components of a fiber-reinforced composite. It is now possible – and being commercially demonstrated – to have molded-in-color composites that weather comparably to existing exterior-grade paints and coatings. Here are some points to consider when developing your compound.

·         Start with the base formulation. Even innocuous system components such as filler can have significant detrimental effects on the weatherability of a compound. Calcium carbonate, for example, leads to premature chalking, fading, surface erosion and fiberglass bloom. Consider clay and/or ATH as alternative fillers.

·         Think about chemical interactions. Certain types of resins possess known sensitivities to sunlight. However, the interactions that occur among low-profile additive, filler, fiber, monomer and resin, leading to unexpected and dramatic failure, are often surprising. Even the surface treatment on the reinforcing fiber can play a significant role in promoting or limiting degradation, to say nothing of inhibitor and/or initiator selection.

·         Understand the end-use application. What is the weatherability objective? There is little value in formulating a compound for five-year outdoor durability if the end-use application involves limited or indirect exposure to sunlight. However, if the application involves intense direct exposure to sunlight over a number of years, it is best to prepare and test for the worst-case scenario.

·         Contact your colorant supplier. Relationships among colorants, additives and other components of a composite matrix play a significant role in limiting or extending the durability of outdoor materials. Chromaflo has expertise in understanding these relationships and can help identify the appropriate colorant and additive package to meet the objective.

Market impact
There is tremendous growth opportunity for composites to replace traditional materials such as metals, concrete and wood, particularly in the construction and automotive markets. Composites offer a number of advantages over these materials, including high strength and low weight. They are also noncorrosive and cost effective.

The European and North American automotive markets, where initiatives are in place to increase overall fuel economy, present a notable growth opportunity. While many engineering approaches can achieve this, reducing overall vehicle weight through increased use of composites is a popular approach. Current composite penetration in the automotive market is relatively low, leaving plenty of opportunity for growth through innovation.

Historically, the perception that outdoor applicability of unpainted, molded-in-color composites is limited has been an obstacle to using composites in exterior construction and automotive applications; appearance is subject to noticeable change within years, if not months, of being placed outdoors. But advances by colorant suppliers in colorant and additive technology are providing composites producers with a new advantage over competitive materials, enabling the growth of the overall market size for composites.

UV-stable colorant technology for exterior applications can help expand the market for composites. The key to success is creating awareness with composite compounders and molders about the improved weatherability enabled by the use of these colorants, as well as how they are used, how to properly formulate materials to take advantage of the increased stability and why new UV-stable colorant options are vital to the future of their industry.

Interested in learning more about UV-stable colorant technology? Chromaflo Technologies is a leading provider of colorant technologies for the thermoset plastics industry. Visit www.chromaflo.com to find innovative colorant solutions for your exterior applications.

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