Sustainable Heat Shrink Tubing for Harsh Environments

(Source: newlifestock/stock.adobe.com; generated with AI)

Many engineers face a difficult choice between pursuing sustainable components in product design and operations or continuing with engineered plastics that have decades of proven mechanical and thermal reliability in harsh environments. In automotive, industrial, and information and communication technology (ICT) systems, components are at risk of fatigue and failure because they are exposed to thermal cycling, vibration, and long-term contact with chemicals, fluids, and dust.

Plastics derived from fossil fuels may have been the default choice for performance in extreme environments, but regulatory pressures and corporate sustainability initiatives are leading engineers to rethink procurement pathways. Bio-based materials are defined as polymers made from renewable feedstock like sugarcane, corn, or cellulose, and they offer an alternative for reducing carbon footprint. Their promise is driving demand and leading engineers to reevaluate the bill of materials (BOM) needed for sustainable sourcing. Already at $41 billion (USD) in 2023, the market for such products is predicted to grow at a rapid 25 percent rate to $396 billion (USD) by 2033.^[1]

For engineers, the choice is not as simple as swapping one material for another. To be considered reliable in harsh environments, bio-based materials must meet the same demanding specifications as fossil-based plastics. Some of these requirements include chemical resistance to perform under harsh and corrosive conditions, as well as dust, vibration, and other environmental challenges. Effective moisture sealing should block liquid ingress that could corrode or weaken wires and connectors, causing them to fail. High flame retardancy meets safety requirements in automotive, aerospace, and industrial applications. Materials must also be resistant to thermal cycling, mechanical stress, and fatigue to survive repeated load and temperature changes. Additionally, products must comply with certifications such as UL 224 for electrical insulation, RoHS, REACH, UL94, and ELV, which validate performance and global environmental standards.

To help navigate this difficult choice, this blog explains how bio-based polymers can be engineered for durability and where they can effectively replace traditional plastics in harsh environments. It also explores BIOFUSE heat-shrink tubing and caps from TE Connectivity, showing how renewable polyolefins can match the performance of traditional plastics when carefully processed and rigorously tested.

Understanding Bio-Based Materials in Engineering

It’s important to point out that "bio-based" does not mean biodegradable. Many bio-based polymers, such as bio-based polyolefins, are chemically identical to their fossil fuel-based counterparts, polyethylene and polypropylene. Although their sourcing route might be different, bio-based materials can be engineered through various techniques to deliver precise property standards depending on the final application.

First, like all polymers, performance depends heavily on processing. Engineers can adjust crystallinity in bio-based polymers by fine-tuning cooling rates and processing pressures. Higher crystallinity packs the molecules more tightly, which strengthens the material and directly influences shrink recovery, tensile strength, and dimensional stability.

Another critical processing technique is electron-beam irradiation, which increases crosslinking of polymers. This step improves heat resistance and environmental sealing, which are necessary for environments that need superior insulation and ingress protection.

Beyond processing, formulation adjustments such as incorporating flame retardants or antioxidants can increase functionality by helping bio-based materials meet flame-retardancy and aging requirements.

These engineered properties are very important in heat shrink tubing, where shrink ratio, recovery, and sealing performance depend on precise material behavior to protect connections from heat, moisture, and chemical ingress. These same factors also ensure that components resist warping or degradation under temperature extremes, mechanical loads, and chemical exposure.

Heat Shrink Tubing & Caps

Two commonly used components in a variety of automotive and commercial transportation sectors are heat shrink tubing and caps. This widespread use is due to their ability to effectively illustrate the many stringent performance requirements placed on everyday equipment.

Heat shrink tubing and caps are a comprehensive insulation solution for wires, connectors, and other components. Made of thermoplastics, the tubing becomes pliable upon heating and solid with cooling. It’s heated to “shrink” and form a snug fit around the component it is protecting. Shrink ratios determine the degree of tubing contraction and compatibility with wires or connector equipment. The cap provides a physical barrier or closure between sets of components in complex engineering equipment. Since the cap operates in the same environment as the tubing, it must meet similar performance requirements. A key performance factor is high thermal endurance, so tubing shrinks predictably during installation and remains stable in long-term operation. These components also need to withstand rapid thermal cycling, mechanical stress and fatigue, fluid ingress and chemical exposure, and meet industry specifications for aging, vibration, and temperature extremes.

Bio-based heat shrink tubing and caps that meet this broad range of specifications are effective replacements for equivalent plastics. The BIOFUSE line of products from TE Connectivity demonstrates how renewable polyolefins can be engineered to meet these specifications in practice.

Sustainable Connectivity Solutions

BIOFUSE, TE Connectivity’s series of bio-based heat shrink tubes and caps, demonstrates that bio-based polyolefins, when properly processed, can perform in harsh environments (Figure 1). BIOFUSE applies irradiation-based crosslinking to bio-based polyolefins, improving their heat resistance and environmental sealing. Since the polymer is chemically equivalent to fossil-based versions, BIOFUSE can be introduced into existing designs as a drop-in replacement for ES2000, RBK-ILS, and ES-Cap without tooling changes, requalification, or added cost.

The product line includes two primary components: Bio Innovation Splice Sealing (BISS) and Bio Innovation Cap (BICAP). BISS operates across a temperature range of –40°C to +125°C, while BICAP is rated from –40°C to +105°C. Both maintain a 4:1 shrink ratio, and the material’s full recovery temperature is +135°C. These performance characteristics, which depend directly on controlled crystallinity and crosslinking, aim to prolong the life and performance of sealed products.

Figure 1: BIOFUSE BISS and BICAP heat shrink tubes and caps offer a bio-alternative way to deliver electrical insulation and optimal sealing capabilities. (Source: Mouser Electronics)

BIOFUSE has been tested under TE's 108 specifications, which evaluate sealing with hot-melt adhesive to prevent moisture ingress, mechanical strength, and strain relief under impact and vibration. These products feature flame retardancy, electrical insulation, resistance to automotive fluids, and long-term thermal aging at +125°C for 3,000 hours.

Certified to UL 224 and compliant with RoHS, REACH, and ELV directives, the BIOFUSE series is already being applied in splice sealing for automotive, ICT, and industrial systems. Furthermore, it supports environmental, social, and governance (ESG) and carbon footprint reporting in alignment with frameworks such as the Science Based Targets initiative (SBTi) and ISO 14067, showing how even partial substitution of components like tubing and caps can contribute to sustainability targets.

The Path to Smart Sustainability

When considering lower-carbon-footprint materials, engineers must evaluate performance alongside sustainability. Manufacturing processes, end-of-life treatment, and compliance with standards are all factors to take into account. Bio-based polymers are a sustainable alternative since they share the same chemistry as conventional polyolefins without sacrificing performance.

In the quest for sustainability, TE’s BIOFUSE series of bio-based tubing and caps help engineers achieve the same reliability as fossil-based parts in automotive, ICT, and industrial systems. While these materials are not a universal replacement for every application, they can be a targeted substitution that works for technical specifications while being environmentally meaningful.

In meeting sustainability requirements, every contribution matters, and the pressure to lower the carbon footprint of all operations is significant. When engineers can meet demanding design requirements without retooling or compromising performance, they take a step toward sustainability without sacrifice reliability. Bio-based materials fulfill part of these complex calculations by virtue of their sourcing from reusable feedstock. In addition, their reliability and durability under harsh everyday operating conditions make them effective replacements for conventional plastics.

Source

[1]https://www.sphericalinsights.com/reports/bio-based-materials-market

Poornima Apte is an engineer turned writer with B2B specialties in robotics, AI, cybersecurity, smart technologies and digital transformation. Find her on Twitter @booksnfreshair.