再生PEEK的性能与颜色:Tm343℃不缩水,但分子量掉了植入就不敢用

塑料知识科普 发布时间: 2026-09-15 3708 阅读

What is the biggest fear when buying recycled PEEK?

It's not that it's not heat-resistant. This product has a melting point of 343°C, can be used continuously at 250°C, and is almost immune to almost anything except concentrated sulfuric acid and rich nitric acid—it's a natural hardcore player.

The biggest worry is losing molecular weight. One of PEEK's core selling points is that the molecular chains are long and stable. After each hot processing cycle, molecular weight drops by 10% to 20%, and after three standard recyclings, the typical tensile strength drops by 8% to 12%—customers test the parts and find the strength is a notch lower, then accuse them of cutting corners. You can't even argue on the spot—because the heat-resistant material really hasn't shrunk, but the recycling process shortens the molecular chains.

Anyone making semiconductor CMP retaining rings, compressor wear-resistant piston rings, or automotive transmission bearing cages—who hasn't been seen as good material or labeled as something wrong?

This article thoroughly explains the performance temperament and color of recycled PEEK: which properties remain stable after cycling, which properties lose value after recycling, and why color directly determines what it can do. Read before placing an order, at least you have a plan.

Original Victrex 450G base first: density 1.30 grams per cubic centimeter, which is quite balanced among specialty engineering plastics; melting point 343°C, glass transition temperature 143°C, continuous use temperature about 250°C; tensile strength about 100 MPa, bending modulus 3.8 gigapa; simply supported beam notch impact about 5.0 kJ/m², elongation at break 25% to 50%; Water absorption rate about 0.05% in 24 hours, dimensions don't fluctuate much even in water; Natural UL94 V-0, with wall thickness as thin as 1.5 millimeters, meets standards without any flame retardants.

To put it bluntly, this thing is naturally heat-resistant, wear-resistant, and flame-retardant—a hexagonal warrior.

What about recycled material? Good news and bad news. The good news is, even after the molecular weight drops, tensile strength is basically retained—recycled samples can still be pulled around 90 MPa in actual tests, with limited reduction. The bad news is that the notch impact loses more than the specific strength, and ductility deteriorates accordingly.

Remember this asymmetry: it can withstand tensile performance cycles, but not after impact performance cycles. Choosing recycled PEEK is essentially a balance between the two.

Tm343°C and continuous 250°C are golden signatures

343°C is PEEK's financial backbone.

Let's correct a misconception: PEEK is a semi-crystalline material with a clear melting point. Unlike PEI and PPSU, which have only a glass transition temperature and no melting point, it suddenly melts at 343°C. So it can operate continuously at 250°C year-round and withstand 300°C in the short term.

Compare and understand: PEI has a continuous operating temperature of about 170 to 180°C, PPSU about 180°C, and PEEK is much higher. This is why it is specifically targeted in high-temperature scenarios such as aerospace structural parts, semiconductor CMP retaining rings, and downhole tools.

There are also costs: to process this thing, the barrel temperature must be raised to 360 to 400°C, and mold temperature 170 to 200°C is still mandatory—if the mold temperature isn't high enough, crystallinity won't increase, and the parts will flutter in size as soon as they come out. Ordinary injection molding machine barrels simply can't handle this temperature, so they need specialized barrels. This is the flip side of the golden signboard: the higher the temperature you can withstand, the more suffering you have to endure during processing.

Molecular weight drops faster than hair

The reputation for temperature resistance is solid, but molecular chains are shorter after every cycle.

The principle is simple: Each PEEK melt processing occurs at a high temperature range of 360 to 400°C, combined with oxygen in the air, and the aromatic rings and ether bond ketones are gradually sheared by the aging of the thermal oxygen. Once the chain is short, the molecular weight decreases, and melt fluidity increases. Stretching can still be supported by inter-chain forces, and after three recoveries, typically reduces by 8% to 12%; But impact is different—impact tests test whether the chain segment can absorb energy through entanglement under high-speed deformation. If the chain is short, fewer tangling points cause the notch impact to drop downward, which is more noticeable than when stretched.

There's a pitfall here that needs to be clarified in advance: this is a 10% to 20% reduction in molecular weight per cycle, and an 8% to 12% reduction in tensile after three cycles—these are PEEK-specific data and cannot be applied to other products. In industry, PIR offcuts at 25% to 75% combined with appropriate packing systems can maintain acceptable mechanical properties; To stabilize performance, 30% to 50% virgin new material is often mixed with recycled material for refresh. But there's a red line: for medical implants and clean-grade semiconductors, regulations prohibit any recycled material—this isn't a negotiation, it's the bottom line.

Foshan has a customer who makes wear-resistant piston rings for compressors. Previously, I wanted to buy domestic recycled PEEK for cheap prices. Each batch of chip had notch impact drifting from 4.2 to 2.8 kJ per square meter. The punched piston rings wore abnormally within less than 500 hours after installation. Two batches were returned in three months, with a return rate as low as 8%. Later, they switched to fixed imported materials from Southeast Asia—natural color unfilled sprue material and black wear-resistant grade sprue material separately. Imported material color is controllable, natural color is sufficient, and each truck comes with molecular weight and tensile test reports. Tensile strength is stable above 90 MPa, notch impact is stable above 4.0 kJ/m², and the return rate is reduced to 0.5%.

To put it plainly, imported materials have controllable colors, natural color sources are abundant, and performance is stable. On the mass production line, wear-resistant parts don't require remaking of benches every batch or risk lifespan with the whole batch.

Color is the second face of recycled PEEK .

The color of recycled PEEK directly determines what it can do.

Natural light brown amber is the natural color of unfilled resin and is the most expensive grade—natural PIR sprue material has a single composition, high cleanliness, and is highly scarce; Black is colored with carbon black, offering strong coverage, wide material availability, commonly used in wear-resistant bearings; Carbon fiber reinforced is black, high strength and rigidity; Glass fiber reinforced is light gray with white color and high rigidity.

Why is unfilled natural color grade the rarest? Because PEEK is processed at high temperatures, molecules inevitably age by heat and oxygen, causing the color to deepen step by step—from light brown to yellow, then to brown, then to black, and this discoloration is irreversible. If you use recycled natural color material to make exterior parts, the color simply can't be suppressed. A large part of the price difference between natural pure resin and glass fiber reinforcement is a premium paid for the word 'natural color. '

The color change mechanism is not complicated: repeated high-temperature processing combined with thermal oxygen aging forms a chromophore on the molecular chains, and with impurities accumulating bit by bit, the color gets darker and darker. Another point to note is that PEEK is extremely sensitive to contamination. Any black spots, calcium carbonate, or impurities mixed in will form black spots on the final part, and Victrex has clearly pointed out this issue.

Here's a simple logic: for exterior parts that want natural color, don't expect recycled materials; For internal wear-resistant parts that aren't afraid of black, black is more cost-effective. Choosing the right color saves you the cost of color matching and the hassle of color changes.

Wear resistance, self-lubrication, and chemical resistance are the last stubborn ones.

If temperature resistance is PEEK's trademark, then wear resistance and chemical resistance are its bottom line.

PEEK alternating aromatic rings and ether ketone groups on the molecular chain, the structure is inherently hard and tough, with a low friction coefficient and wear resistance far superior to nylon and graphite nylon. For places where repeated friction is needed for bearing cages, gears, and piston rings, it's a regular customer.

Chemical resistance is even more solid: resistant to most organic solvents, acids, alkalis, and oils, except for strong oxidizing agents like concentrated sulfuric acid and concentrated nitric acid. It also excels in hydrolysis and steam resistance—it can withstand 134°C steam repeated sterilization over 1000 times with no significant performance decline, which is key to its use in medical and food fields. Its dielectric properties are also stable, with little drift across a wide temperature and frequency range, making it suitable for insulating areas like electronic connectors and coil frames

But there's an unavoidable pitfall: the color deepening caused by high-temperature processing is irreversible. If you want to make light-colored, natural color parts, repeatedly recycled materials can't hold the color back. That's why most recycled PEEK in the industry goes black—using black to cover color differences, out of sight is out of sight. That's why high-end medical and semiconductor clean parts prefer to choose the original color, while recycled materials honestly use black masking for wear-resistant structural parts. Wear resistance and chemical resistance are the costs given by molecules, while color deepening is an unavoidable cost in the recycling process.

Four sub-directions, explained in one sentence

High temperature resistance grade: Focuses on a melting point of 343°C and continuous use temperature of 250°C, making long-term heat-resistant aerospace replacement parts and semiconductor equipment structural parts.

High Wear and Toughening Grade: After recovery, molecular weight decreases and impact worsens; relying on blending ratio and filler to stabilize notch impact within usable range, used for bearings, gears, and piston rings.

Natural Flame Retardant Grade: Does not rely on flame retardants or natural V-0, but is used for electronic, electrical, and connector frameworks that require flame retardant smoke and toxicity.

Chemical Resistance Grade: Resistant to most acids, alkalis, solvents, and oils, resistant to repeated steam sterilization, used for chemical seals and medical device accessories.

Final Notes: Seven Material Selection Tips

1. Focus on Temperature Resistance: Melting point 343°C, continuous 250°C, this is PEEK's cost—don't replace it with ordinary engineering plastics;

2. Monitor molecular weight: reduce by 10% to 20% per cycle, and after three recyclings, tensile reduction is 8% to 12%, with impact loss more pronounced than tensile reduction;

3. Monitor blending: PIR fillers can be blended with 25% to 75%, commonly using 30% to 50% virgin new material for refreshing and stabilizing performance;

4. Monitor color: natural amber is rare and most expensive, black is available in large quantities and cheap, choose based on appearance requirements;

5. Monitor yellowing: color deepening during high-temperature processing is irreversible; do not repeatedly recycle natural color parts;

6. Monitor wear and chemical resistance: low friction, solvent resistance, and resistance to thousand-steam are the costs provided by molecules;

7. Keep an eye on the red line: medical implants and semiconductor cleanrooms are prohibited from using recycled materials—don't touch this rule.

In conclusion: The performance record of recycled PEEK is essentially that it can withstand temperature and wear resistance, but cannot withstand molecular weight shocks. A melting point of 343°C and continuous use at 250°C are inherent advantages, and even after cycling, they can still stand; Molecular weight is the chopstick that breaks easily during recycling; whether mixing is accurate directly determines whether your mass-produced parts crack. Ningbo Kelong New Materials Co., Ltd. has been selecting modified PEEK and recycled materials for many years, sourcing through Southeast Asian import channels. The imported materials have controllable colors, sufficient natural color sources, and stable performance. Dozens of similar selection cases are handled annually, essentially helping you stop the performance assassins before mass production

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