Supply chains were drastically affected by COVID-19, and no industry escaped from the fallout the pandemic created. While industries are mostly on the road to recovery now, it highlighted material shortages that were not noticeable before. One of the materials that was impacted the most was plastic. Prices increased and production was everything but stopped during the pandemic. However, this led to some great innovation in material development and several plastic alternatives were developed to resin that gave product developers options.

What is resin?

Resin is sometimes referred to as a fancy plastic, however this is not necessarily true. Natural resins are created by plants to create a protective layer for themselves if they are injured. Synthetic resins are created to form effective coatings, composites and structural adhesives. Synthetic resins are a blended composite, which is then molded rotationally into pliable and strong products that can copy the look of metal and stone materials at a fraction of the weight and significantly lower cost.

There are two main types of resin, epoxy and polyester. The main difference between the two is how they cure. Epoxy resin is one of the most well-known and best resin types, as it has excellent moisture and chemical resistance. It also has impressively low shrinkage during its curing time, great electrical and insulation properties, resistance to impact and a long shelf life. Epoxy resin is generally packaged as two different compounds – resin and a hardener. These must both be mixed together to start the setting process and produce the plastic-like substance that is desired. Polyester resin is just one substance that hardens due to the application of UV light or a catalyst. It is important to note that because of how polyester resin is made, it also comes with an expiration date. Both of these resins have different characteristics and that makes them suitable for different applications.

As a direct result of the plastic shortage substitution options were developed based around the various material properties that were desired, and the intended application of the part. Each of these lesser-known plastics could be used instead of the main plastics that were commonly used, such as polycarbonate, acrylonitrile butadiene styrene and polypropylene. Let’s go through some of the plastic alternatives to resin that were developed.

Polysulfone (PSU)

This particular resin is transparent, amorphous and pale-amber thermoplastic that is high performance and features decent melt stability. This means that it will allow fabrication by the typical processing methods used on thermoplastics. PSU also possesses excellent electrical, thermophysical and mechanical properties along with brilliant hydrolytic and chemical stability. These characteristics combine to make up a resin that is a great fit for parts and components that are regularly exposed to water and steam, for instance plumbing parts, membranes for water treatment, parts for medical devices, gas separation and many more.

Polyphthalmide (PPA)

PPA is a semi-aromatic polyamide that offers a somewhat cost-effective alternative to fully-aromatic, more expensive aramids. It possesses a combination of aliphatic and aromatic groups, and it significantly decreases moisture absorption. This in turn results in more stable properties and fewer dimensional changes. This particular alternative to resin is a great choice for parts and products that must undergo prolonged exposure to high temperatures and harsh chemicals. Typical applications of PPA are coolant pumps, resonators, motor parts, bearing pads and much more.

Polyphenylene (PPS)

Some main features of PPS are its poor solubility and extremely high melting point, and it requires specific manufacturing to make parts out of this material. However, once manufactured PPS has brilliant chemical and heat resistance, high structural and tensile strength, and good dimensional stability down to its aromatic ring structure. Components made with PPS also possess flame retardant and great electrical properties, resulting in being a commonly used polythioether. Typical applications for PPS are electronic and electrical parts, and mechanical components in precision engineering and the automotive industry.

Polyphenylene oxide (PPO)

PPO features great impact and tensile strength while also being resistant to a multitude of chemicals, water and steam. However, it is prone to cracking under stress and also has a problem with melt processing as it has a high glass-transition temperature. Because of this, it is very commonly combined with high impact polystyrene in order to be utilized in the electronics and automotive industries, for catalyst supports, fan impellors, pump parts and more.

Syndiotactic polystyrene (SPS)

Commonly known by its trade name Xarec, this plastic alternative is the very first SPS resin. This innovating resin was made to allow for a number a characteristics that product designers highly desired. It has resistance to hydrolysis, chemical resistance to corrosion by various alkalis and acids, like antifreeze and automobile oil, and is also quite resistant to heat. It possesses a low specific gravity, reducing the cost and weight of parts. SPS is a good fit for electronic parts that are used in many hybrid electric vehicles, along with essential components that can be found in the common home. It is generally viewed as an environmentally conscious choice when it comes to resin.

It can be frustrating when the supply chain is affecting the ability to manufacture parts and produce finished goods. However, with these alternatives manufacturers have viable alternatives.

So, what do you think of these five plastic alternatives to resin? Do you think any of these could replace resin altogether?

To contact the author of this article, email GlobalSpeceditors@globalspec.com