Reinforced thermoset composites are a well-established technology that is widely used in end-use applications. With their excellent combination of strength, stiffness and weight, reinforced thermosets have established themselves as the material of choice for many mechanical engineers. In this article, we will explore some of the most recent developments in reinforced thermoset materials with particular focus on glass fibre and carbon fibre-reinforced thermoset composites. We’ll look at three key trends emerging in the industry today: growth of advanced hybrid materials based on thermosets;.
Reinforced Thermoset Composites: A Brief History
The earliest reinforced thermoset composites date back to the early 1900s, when phenolic and cellulosic resins were first used as fiber-reinforced thermoset binders. Many other thermoset polymers have since been developed and commercialized, including polyimides, polyesters, phenolic resins, polyurethanes, polyethers and polysulfides. One of the first commercial uses of carbon fiber-reinforced thermoset composites (CFR TPF) was in the construction of the Space Shuttle’s wings and fuselage first launched in 1981. Carbon fiber-reinforced phenolic and glass fiber-reinforced phenolic composites have been used to construct the wings and fuselage of the Boeing 737 plane since 1994 and the Airbus A-320 plane since 1996.
Advanced Reinforced Thermoset Composites
New materials and new processing techniques have enabled a new generation of reinforced thermoset composites that offer even greater combinations of properties, reduced fabrication costs and shorter processing times. Such advanced and next-generation thermoset composites address four key market opportunities: Advanced industrial laminate thermosets are particularly relevant to the air and space industries, where weight reduction is a key driver. High-performance CFR TPF laminates allow for the construction of lighter, stiffer and stronger structures. Fibrous reinforcements made from advanced polymer fibers such as high-strength polyethylene (HSPE), high-modulus polyethylene (HM PE), polyether-ether-ketone (PEEK) and aromatic polyimides (AI) have wide-ranging applications in both commercial and military industries.
Growth of Industrial Laminate Thermosets
Industrial thermosets have been around since the early 1990s, when the first glass fibre-reinforced phenolic (GRP) composites were developed. In 1996, the first carbon fibre-reinforced phenolic (CFRP) composites were commercialized, followed by glass fibre-reinforced phenolic (GRP) in 2001. CFR TPF has been growing steadily since the early 2000s with production reaching over 5 million tonnes in 2018. GRP and CFR TPF are the two dominant industrial thermoset composites, accounting for over 90% of the total commercial output of thermoset composites. CFR TPF is forecast to grow at a CAGR of 2.8% between 2019 and 2025, with GRP experiencing a slightly lower growth rate of 2.7%. By 2025, the CFR TPF market is expected to reach 9.2 Mt and the GRP market will grow to 8.5 Mt.
Differences between glass, carbon, and cloth based composite reinforcement
The main differences between carbon fibre, glass fibre and cloth based composite reinforcement are these: – Higher density of carbon fibre relative to glass fibre: Carbon fibre (1-3 g/cm3) is about 2-3 times denser than glass fibre (0.7-1.2 g/cm3). This affects the strength of the composite, with a higher density usually resulting in higher strength. – Carbon fibre has higher thermal conductivity than glass fibre: Carbon fibre has a thermal conductivity around 30-40 W/m K while glass fibre has a thermal conductivity of only 12 W/m K. This means that carbon fibre has a higher rate of heat transfer through the composite structure than glass fibre. This affects the amount of heat that can be generated within the composite, and the rate at which it is removed. – Carbon fibre has lower thermal expansion than glass fibre: Carbon fibre has a thermal expansion of only 1.5-2.5 ppm/°C while glass fibre has a thermal expansion of 3-5 ppm/°C. This means that carbon fibre is less susceptible to thermal expansion than glass fibre, which leads to a better match between the composite structure and the surrounding materials.
Summary
The article explores three key trends emerging in the industry today: growth of advanced hybrid materials based on thermosets, development of thermally stable CFR TPF laminates with extended shelf life, and increased usage of monolithic CFR TPF components with embedded electronics. These trends will enable the further commercialization of advanced reinforced thermoset composites, with positive implications for the engineering industry.