What are Differences Between Plastic and Elastomer?

The main difference between plastic and elastomer comes down to flexibility and shape retention.

Plastics are rigid or semi-rigid. Once they bend or break, they don’t bounce back.

Elastomers are flexible. They stretch, twist, or compress and return to their original shape.

Below, we’ll take a closer look at how these materials differ and the conditions where each works best.

What Is Plastic?

Plastic is a type of polymer that’s rigid or semi-rigid and holds its shape under stress.

Unlike elastomers, plastic doesn’t return to its original form once bent, stretched, or broken.

Some plastics, like PTFE, PFA, and PVDF, resist chemicals and high temperatures, making them ideal for valve linings.

What Is an Elastomer?

Elastomers are a special type of polymer that stretches, twists, or compresses and then snaps back to its original shape.

This rubber-like flexibility comes from their molecular structure, which allows them to absorb impact without breaking.

Common elastomers like EPDM, NBR, and FKM (Viton) are used in seals, gaskets, and pinch valve sleeves to prevent leaks.

Key Differences Between Plastics and Elastomers

Both materials are polymers, but their structure and behavior define how they’re used. Here’s a closer look at the main differences.

Flexibility and Shape Retention

Plastics are stiff and maintain their form unless enough force breaks or deforms them. Once bent or cracked, they don’t return to their original shape.

Elastomers are stretchable and resilient. They can handle repeated stretching, bending, and compression without losing their form.

Heat Resistance

Plastics have varying levels of heat resistance. Some soften or melt under high temperatures, while thermoset plastics can withstand extreme heat without changing shape.

Elastomers, like silicone, can handle high temperatures while staying flexible. This makes them useful in applications exposed to heat, like engine components and industrial seals.

Chemical Resistance

Most plastics resist chemicals, making them ideal for industrial and medical applications.

Elastomers can resist oils and solvents, but some may break down when exposed to harsh chemicals. The level of resistance depends on the type of elastomer used.

Impact Absorption

Plastics can be brittle, meaning they crack or break under sudden impact.

Elastomers absorb shock well, which is why they’re used in tires, gaskets, and vibration-dampening applications.

Durability and Wear Resistance

Plastics are tough and resist scratches and wear.

They work well in parts that handle friction or rough materials without breaking down.

Elastomers are softer and more flexible, but they wear out faster under pressure and movement.

Are Elastomers a Type of Plastic?

People lump elastomers and plastics together, but they’re not the same thing.

Some elastomers share traits with plastics, but natural rubber isn’t plastic—it’s biodegradable and completely different.

How Are Elastomers Used?

Because they stretch without breaking, elastomers work well in things that need to bend and flex without wearing out.

You’ll find them in phone cases, resistance bands, car suspension parts, and shoe soles.

Where Are Plastics Used?

Plastics come in two main types: thermoset and thermoplastic.

Thermoset plastics harden permanently, making them ideal for things like circuit boards.

Thermoplastics melt and reshape easily, so manufacturers use them for times like water bottles, storage bins, and car bumpers.

Comparing Rubber and Plastic

Rubber is a type of elastomer, but it works differently from plastic. Here’s a quick comparison:

Feature	Plastics	Elastomers (Rubber)
Flexibility	Rigid or semi-rigid	Highly flexible
Shape Memory	Holds shape under stress	Returns to original form
Heat Resistance	Some soften or melt	Handles extreme heat
Impact Resistance	Can crack or break	Absorbs shock well
Common Uses	Containers, pipes, gears	Seals, tires, dampeners

How Do Plastics and Elastomers Apply to Valves?

Both plastics and elastomers are used in valves, but they do different jobs.

Plastics like PTFE, PFA, and PVDF line the inside of valves to protect against chemicals and corrosion.

These materials work best in industries like chemical processing and food production, where fluids can be aggressive.

Elastomers like EPDM, NBR, and FKM are used in pinch valve sleeves because they’re flexible and absorb impact.

At Lianke Valve, we manufacture high-performance fluorine-lined and pinch valves designed for tough conditions.Need help finding the right valve for your system? Talk to our team today