Thermoplastic Elastomer (TPE) vs. Liquid Silicone Rubber (LSR): How to Choose the Right Material for Your Product

Samples of Thermoplastic Elastomer (TPE) Parts Made by Moraine Plastics

Let’s be honest—choosing the right material for your product isn’t always straightforward. On paper, thermoplastic elastomer (TPE) and liquid silicone rubber (LSR) might look pretty similar. Both are flexible, both are used in injection molding, and both show up in everything from kitchen tools to medical devices. But dig a little deeper, and they’re not just different—they’re designed for different jobs.

At Moraine Plastics, we see this question pop up all the time: Should I go with TPE or LSR for my design? And the answer, like most good answers, is: It depends.

Let’s break it down in plain English.

First Things First: What Are We Dealing With?

TPE: The Flexible All-Rounder

TPE is short for thermoplastic elastomer. If that sounds technical, don’t worry. All it really means is: it’s a rubbery material that behaves like plastic when you process it. That’s a big deal. You can shoot it through your standard injection molding equipment without special tooling. No fancy curing ovens, no long cycle times.

It’s flexible, colorful, and comes in a range of hardness levels. If you’ve ever gripped a power drill handle, chewed on a soft toothbrush grip, or used a pair of kitchen tongs—that’s probably TPE.

Designers love it because it’s:

• Easy to work with.

• Friendly to tight timelines and tight budgets.

• Overmolds beautifully onto rigid plastics.

• Recyclable in many cases.

LSR: The Performance Purist

Then there’s liquid silicone rubber, or LSR. This stuff is in another league when it comes to performance. It starts out as a pourable liquid, then cures into a solid rubber in the mold—typically at high temperatures and under pressure.

It takes more effort to process (you’ll need specific LSR tooling and a different injection setup), but in return, you get a material that shrugs off high heat, resists chemicals like a champ, and keeps its flexibility for years.

It’s the go-to material for:

• Medical devices

• Seals and gaskets in cars and appliances

• Baby products and wearables

• Anything that needs to be sterilized, flexed, or live in a harsh environment

“We’re not here to sell you on one material or the other,” says Gerry Ford, President of Moraine Plastics. “We’re here to figure out what your part needs to do, and then get you the material that won’t let you down five years down the road.”

Key Differences: TPE vs. LSR at a Glance

Criteria	TPE	LSR
Processing	Standard injection molding	Requires LSR-specific tooling and curing
Cost Efficiency	Lower tooling and production costs	Higher initial investment
Cycle Time	Fast, ideal for high-volume production	Longer due to curing process
Heat & Chemical Resistance	Moderate	Excellent—ideal for extreme environments
Biocompatibility	Available in select grades	Naturally biocompatible, medical-grade ready
Design Complexity	Supports moderate detail	Excels at intricate and flexible geometries
Sustainability	Often recyclable	Not typically recyclable

Use Case #1: Leveraging TPE for Speed and Flexibility

One of our longstanding clients needed to develop a line of hand tools with ergonomic grips that felt soft in the hand but could be produced efficiently across multiple SKUs. TPE was the clear solution. It molded easily over a rigid plastic core, allowed for vibrant color matching, and supported high-speed production without specialized tooling.

The result? A high-quality consumer product line with a comfortable grip, a distinctive look, and a cost structure that made sense for retail. TPE allowed them to move from design to production without significant delays or capital expenditure.

Use Case #2: Relying on LSR for High-Performance Demands

In contrast, a medical startup came to us with a product that required skin contact, daily wear, and the ability to withstand repeated sterilization. Their design included fine details, flexible geometries, and the need for absolute material safety.

In this case, LSR was the superior choice. Its thermal stability and inherent biocompatibility made it ideal for healthcare applications, and its resistance to body fluids and cleaning agents ensured the product would hold up in real-world use. Although the tooling and cycle times were more demanding, the long-term performance of the product made the investment worthwhile.

Factors to Consider When Choosing TPE or LSR

Choosing between TPE and LSR isn’t just a matter of material properties—it’s a matter of aligning those properties with your product’s specific requirements. Here are a few key considerations:

1. Application Environment

Will your product be exposed to high heat, chemicals, or UV light? If so, LSR typically outperforms TPE in these conditions.

2. Design Complexity

Are you working with intricate features, thin walls, or flexible elements? LSR’s flow characteristics and curing process allow for more complex part designs.

3. Cost and Lead Time

If you’re under pressure to reduce tooling costs or accelerate production timelines, TPE may be the more practical option—especially if your part doesn’t require LSR’s advanced performance.

4. Compliance and Safety

Does the product require food-grade or medical-grade material? LSR is naturally biocompatible and easier to certify for stringent standards.

5. Sustainability Goals

TPEs are often recyclable, depending on the grade. For companies focused on sustainability, that may be a factor in material selection.

Best Practices for Each Material

Working with either material requires thoughtful design and process planning. At Moraine, we help customers optimize part and mold designs for manufacturability, whether they choose TPE or LSR.

Designing with TPE:

• Maintain consistent wall thickness to reduce shrinkage and warping.

• Incorporate textures or grip patterns for better user experience.

• Select TPE grades that are compatible with the base material in overmolded parts.

Designing with LSR:

• Design for the flow of a low-viscosity liquid—avoid sharp corners or thick transitions.

• Use proper draft angles and parting line placement to avoid flash.

• Account for post-curing steps if regulatory compliance or added performance is required.

Final Thoughts: Material Matters

At the end of the day, the choice between TPE and LSR is not about picking the “better” material—it’s about choosing the right one for your product’s goals.

If you’re producing high volumes and looking for efficiency, TPE offers a combination of speed, flexibility, and affordability. If you need long-term performance under tough conditions, or are designing for skin contact or sterilization, LSR offers proven durability and safety.

Either way, you don’t have to make that call alone.

At Moraine Plastics, we’re here to collaborate with you—early in the process, when materials decisions matter most. We bring decades of experience in high-volume injection molding and a clear-eyed understanding of what it takes to deliver precision parts at scale.

Let us help you turn your concept into a manufacturable, market-ready reality—with the right material from the start.

Frequently Asked Questions: TPE vs. LSR

Q1: What is the main difference between TPE and LSR in injection molding?A: TPE (thermoplastic elastomer) is a melt-processable plastic that behaves like rubber but can be molded using conventional thermoplastic equipment. LSR (liquid silicone rubber), on the other hand, is a two-part liquid material that requires high-heat curing in specialized LSR molds. The primary difference lies in how they are processed and the performance they deliver in the end-use environment.

Q2: Which material is more cost-effective for large production runs?

A: TPE is generally more cost-effective for high-volume runs due to faster cycle times and lower tooling investment. It’s ideal for applications that don’t require extreme temperature or chemical resistance. However, if durability, biocompatibility, or thermal performance is critical, LSR may justify the higher upfront cost.

Q3: Can both TPE and LSR be overmolded?

A: Yes, both materials can be used in overmolding applications, but the process and design considerations differ. TPE is often overmolded onto rigid plastic substrates like polypropylene or ABS. LSR can be overmolded as well, especially in medical or high-performance parts, but it requires more complex tooling and thermal curing.

Q4: Is LSR safe for medical or skin-contact applications?

A: Absolutely. LSR is naturally biocompatible, hypoallergenic, and resistant to bacteria and bodily fluids. It is widely used in medical devices, wearables, and infant care products. Medical-grade LSR formulations also meet FDA and ISO 10993 standards.

Q5: Can TPE be used in high-temperature environments?

A: TPEs have a temperature range that suits many consumer and industrial products, but they generally do not perform well at sustained high temperatures. If your product will be exposed to prolonged heat (above 120–150°C), LSR is typically the better option due to its excellent thermal stability.

Q6: Which material is more environmentally friendly?

A: TPE has the edge in recyclability. Many grades can be reprocessed, making it a strong choice for companies focused on sustainability. LSR is not typically recyclable, though its durability can reduce the need for frequent replacements in long-life applications.

Q7: How do I know which material is right for my project?

A: The best approach is to consult early with your injection molding partner. At Moraine Plastics, we evaluate the application requirements—performance, budget, timelines, and regulatory needs—to recommend the most appropriate material and process. Sometimes, we even prototype with both to see which performs better in real-world testing.