Siraya Tech Flex TPU vs. Rebound PEBA: Which High-Performance Flexible Filament is Right for Your Project?

Flexible 3D printing filaments have come a long way from the days of slow, jam-prone prints. Today, engineers, product designers, and hobbyists use flexible materials to create everything from custom footwear and protective drone hulls to functional gears and industrial seals.

If you are looking for the best flexible filaments on the market, you have likely run into Siraya Tech’s two powerhouses: the Flex TPU family and the Rebound PEBA family.

While both are elastomeric materials, they are built with entirely different chemical backbones, resulting in stark contrasts in elasticity, weight, printability, and temperature resistance.

In this comprehensive guide, we will break down the differences between Siraya Tech Flex TPU and Rebound PEBA, map out the entire product lineup, and help you choose the perfect material for your next build.

The Quick Showdown: TPU vs. PEBA at a Glance

Before we dive into the specific products, let's understand the core structural and mechanical differences between these two material families:

Deep Dive: The Siraya Tech Flex TPU Family

Standard-setting reliability, high speed, and biocompatibility, Siraya Tech’s Flex TPU is the go-to choice for everyday durability, wear resistance, and ease of use. A major selling point of Siraya Tech’s TPU is its printability; unlike older TPUs that require painfully slow speeds, Siraya Tech's formulations are tuned for high flow and can print up to 5 times faster than standard flexible filaments on modern direct-drive printers.

1. Flex TPU 85A (Soft & Elastic)

• Hardness: 85A Shore Hardness (Softest standard TPU)

• Best For: Wearables (watch straps, wrist braces), flexible grips, ergonomic skin-contact parts, and footwear insoles.

• The Standout Feature: Tested against ISO 10993-5, -10, and -23 protocols, making it certified skin-safe for external-use wearables. Despite its softness, it supports high-speed printing.

2. Flex TPU 95A HF (High-Flow & Tough)

• Hardness: 95A Shore Hardness (Firmer, structural flex)

• Best For: Drone bumpers, protective covers, vibration dampers, and parts requiring high production throughput.

• The Standout Feature: High-flow design that lets you print fast without sacrificing surface finish or structural integrity. Like the 85A, it features ISO 10993 biocompatibility certification.

3. Flex TPU 64D (Semi-Rigid Powerhouse)

• Hardness: 64D Shore Hardness (Rigid, yet compliant)

• Best For: Industrial rollers, functional gears, conveyor components, and structural flex joints.

• The Standout Feature: Acts as a bridge between flexible rubber and rigid engineering plastics. Extremely high wear resistance and structural stiffness while maintaining the impact absorption of TPU.

4. Flex TPU Air (Lightweight & Foamed)

• Hardness: 65A to 85A (Tunable)

• Best For: Lightweight cushioning, comfort pads, and lightweight wearable accessories.

• The Standout Feature: Uses active foaming technology to reduce overall weight by up to 50%, producing a soft, premium cloth-like matte surface.

5. TPU-GF (Glass-Fiber Reinforced Structural Flex)

• Hardness: ~70D (Stiffest in the family)

• Best For: Industrial seals, large-format structural flexible joints, and functional wear parts requiring extreme dimensional stability.

• The Standout Feature: Reinforced with glass fibers, bringing its hardness up to a tough 70D. This material provides incredibly high stiffness, abrasion resistance, and shape retention under load. It is available as both filament and pellets (perfect for large-format pellet printers like the Giga 800) and requires a hardened steel nozzle to print.

Deep Dive: The Siraya Tech Rebound PEBA Family

Elite energy return, lightweight speed, and extreme environment resilience, if TPU is the reliable workhorse, Rebound PEBA (Polyether Block Amide) is the high-tech race car. PEBA is a copolymer that fuses the chemical resistance and strength of a nylon (polyamide) backbone with the elastic bounce of elastomer blocks.

If you are looking to print an airless basketball, high-performance running shoe midsoles, or lightweight drone racing components, PEBA is your material.

1. Rebound PEBA 95A (The Performance Athlete)

• Hardness: 95A Shore Hardness

• Best For: Running shoe midsoles, high-bounce sports equipment, lightweight automotive flex mounts, and industrial gears in motion.

• The Standout Feature: Unrivaled 78% energy return. Instead of dampening impacts (like TPU), PEBA acts like a spring, storing and returning energy instantly. It is also 15% to 20% lighter than standard TPU 95A and has unmatched fatigue resistance.

2. Rebound PEBA 85A (High Bounce, Extra Soft)

• Hardness: 85A Shore Hardness

• Best For: Cushioned athletic midsoles, robotic soft actuators, and cold-environment seals.

• The Standout Feature: Offers the same exceptional 78% energy return as the 95A, but in a softer, more compliant 85A format. This allows for deeper compression and high-response tactile feedback.

3. Rebound PEBA Air (The Ultimate Foam Elastomer)

• Hardness: 70A to 95A (Tunable based on temperature)

• Best For: Elite performance midsoles, ultra-light sporting goods, aerospace or drone components.

• The Standout Feature: The absolute pinnacle of lightweight flexible tech. Rebound PEBA Air uses active foaming to deliver up to a 50% weight reduction compared to standard elastomers. Even better, by adjusting your printing temperature (from 235°C to 270°C), you can dynamically tune the hardness from a plush, soft 70A to a bouncy, firm 95A.

The Hardness & Flexibility Spectrum

Understanding Shore A and Shore D ratings is key to choosing your filament. Here is how Siraya Tech's flexible ecosystem maps out, sorted from softest to firmest:

1. PEBA Air (Softest range: Tunable down to 70A - ultra-plush, foam-like)

2. TPU Air (Lightweight, soft, tunable 65A–85A)

3. Flex TPU 85A / Rebound PEBA 85A (Highly flexible, rubbery, excellent compliance)

4. Flex TPU 95A / Rebound PEBA 95A (Firm flexible, great balance of structure and give)

5. Flex TPU 64D (Semi-rigid, hard-wearing engineering grade)

6. TPU-GF (Firmest flexible: Stiffened with glass fiber to 70D - high rigidity with structural compliance)

PEBA vs. TPU: Which One Should You Choose?

Choose Siraya Tech Flex TPU if:

• You need skin-safe biocompatibility: If you are printing fitness tracker straps, medical braces, or objects that touch skin for prolonged periods, the ISO 10993 certified Flex TPU 85A or 95A is the clear winner.

• You are on a budget: TPU is a highly cost-accessible material compared to premium specialty copolymers like PEBA.

• You value extreme printability: While Siraya Tech's PEBA is easier to print than standard PEBAs, TPU remains a highly forgiving flexible material with excellent bed adhesion and minimal warping tendencies.

• You need structural hardness or glass reinforcement: If your project requires high rigidity or pellet printing (such as the 70D TPU-GF), TPU has the industrial-grade range you need.

Choose Siraya Tech Rebound PEBA if:

• You need "bounciness" and energy return: PEBA's 78% energy return blows TPU’s 40-50% dampening effect out of the water. This makes it perfect for functional sports soles, springs, and impact-return systems.

• Weight is a critical constraint: PEBA is inherently 15-20% lighter than TPU. When using PEBA Air, you can achieve parts that are up to 50% lighter—an absolute game-changer for drone builders and wearable designers.

• Your parts operate in extreme cold: TPU can stiffen and become brittle in cold weather. PEBA retains its rubbery elasticity and impact resistance down to -60°C (-76°F).

• The application requires chemical and flex-fatigue resistance: PEBA's nylon-elastomer backbone is highly resistant to oils, greases, solvents, and handles millions of repeated bending cycles without cracking.

Pro-Tips for Printing Flexibles Successfully

To ensure a flawless print with either of these high-performance materials, keep these golden rules in mind:

• Dry Your Filament! Both TPU and PEBA are hygroscopic (they actively absorb moisture from the air). PEBA, in particular, is highly sensitive to humidity. Wet filament leads to stringing, bubbling, and weak layer lines. Dry your filament in a dedicated dryer at 50-60°C for at least 4 to 6 hours before printing.

• Use a Direct-Drive Extruder: While some rigid TPUs can feed through Bowden tubes, soft elastomers (like 85A TPU and PEBA) perform best with a direct-drive setup to prevent the filament from buckling or binding. Note that PEBA is too soft for automated multi-material systems like AMS.

• Build Plate Adhesion: Clean your build surface with isopropyl alcohol. Texturized PEI sheets or glass plates with a glue stick or Magigoo work beautifully for managing adhesion and preventing warp, especially on large PEBA prints where a bed temperature of 60-100°C is recommended.

Whether you choose the skin-safe, high-speed versatility of Flex TPU or the ultra-lightweight, high-rebound performance of Rebound PEBA, Siraya Tech has a flexible material designed to elevate your 3D printing capabilities.

Ready to start printing parts that bend, bounce, and outlast the competition? Explore the full Siraya Tech Flexible Filament collection today!