买再生PEI最怕什么？
不是耐温不够。这东西玻璃化转变温度217℃、热变形温度200℃上下、天然就过UL94 V-0，天生就是个硬核选手。
最怕的是分子量掉了。MFR从原生的9升到20，做出来的件一摔就裂，客户拿冲击锤一敲就开，回头说你偷工减料。你还没法当场反驳——因为耐温那块料确实没缩水，是回收那一遭把分子链搞短了。
做航空内饰件的、做半导体测试座的、做耐高温连接器的，谁没被“看着是好料、打出来不对”坑过。
这篇把再生PEI的性能脾气和颜色门道讲透：哪些性能循环之后还稳得住，哪些性能一回收就打折，颜色又为什么直接决定它能干什么活。看完再下单，至少心里有本账。
原生ULTEM 1000的底子先摆出来：密度1.27克每立方厘米，在特种工程塑料里算匀称；拉伸强度105到110兆帕，弯曲模量3.3吉帕上下；热变形温度198到210℃；断裂伸长率60%；缺口冲击32到50焦耳每米，纯料本身偏脆；阻燃是天然V-0到5VA，极限氧指数47%到49%；介电强度高，体积电阻率大于10的16次方欧·厘米。
说白了，这东西天生耐温、阻燃、绝缘，是个六边形战士。
那再生料呢？好消息和坏消息各一条。好消息是，分子量掉归掉，拉伸强度基本保留——再生样实测还能拉到100兆帕上下，降幅也就5%到10%。坏消息是，缺口冲击掉得比强度明显，延展性跟着垮。
记住这个不对称：拉伸性能循环后扛得住，冲击性能循环后扛不住。再生PEI选型，本质就是在这两者之间算账。
Tg217℃是PEI的金字招牌
217℃这个数字，是PEI吃饭的本钱。
先把一个认知纠偏：PEI是无定形材料，没有熔点，只有玻璃化转变温度Tg。它不像结晶料那样到某个温度突然熔化，而是在217℃这个点以上逐渐变软。所以它能常年在170℃上下连续干活，热变形温度压在198到210℃。
对比一下就懂：聚砜PSU的连续使用温度大约150℃，PEI高出一大截；要说接近PEEK的长期耐温水平，可价格只有PEEK的四分之一到五分之一。这就是它“性价比之锚”的由来。
代价也有：要把这东西加工出来，料筒温度得拉到350到410℃，模具温度135到180℃还是强制的——模具低于120℃，件一出来就带残余应力，早晚延迟开裂。普通注塑机料筒根本吃不下这个温度，得上专用料筒。这就是金字招牌的另一面：能耐多高的温，加工时就得受多大的罪。
分子量掉得比头发还快
耐温这块招牌结实，但分子链这东西，回收一回就短一回。
原理不复杂：PEI每次熔融加工都在340到410℃的高温区间，加上空气里的氧气，酰亚胺键和醚键被热氧老化一点点剪断。链一短，分子量下来，熔体流动速率就往上走——原生基准9，市售再生样普遍升到20附近。拉伸因为还能靠链间作用力撑着，基本保留在100兆帕上下；可缺口冲击和延展性，掉得比谁都狠。
循环次数也有账：反复挤出3到5次，拉伸强度保持率大约落到80%，颜色一次比一次深。所以行内的经验是，再生料掺新料的比例别贪多，工业场合掺25%到50%是个稳妥区间；要扛冲击的结构件，更得控制着掺。
东莞有家做半导体老化测试插座的客户，之前图便宜拿国内凑的再生PEI，每批MFR从15飘到25，打出来的插座套管过手掰试验，三个月里连续裂了两批，退货率干到9%。后来换成从东南亚进口的固定料源——黑、灰、兰几个颜色水口料分开收，颜色可控、杂质少，每车实测MFR和拉伸值钉在一个窄区间里，再生料掺混比例按实测配死，量产件手掰试验一次过，退货率压到0.5%。
说白了，进口料源颜色可控、黑色料源充足、性能稳定，落到量产线上就是测试座不用每批重做验证、不用拿整批货去赌。
颜色是再生PEI的第二张脸
再生PEI的颜色，直接决定它能干什么活。
黑色是当仁不让的主力。因为PEI在高温下加工，分子难免热氧老化、颜色越变越深，本色料反复回收后黄得像放了多年的老照片。黑色遮盖力强，源头又广——电子电器的黑外壳、工业件的黑壳子，回收出来一大把是黑的，所以黑色料量大、品级杂，两万二到两万五一吨这个区间；黑色光亮级稍好一档，两万五。
兰色最贵，三万八一吨——着色鲜艳度要求高、分拣严，对应下游特定配色，稀缺性溢价；灰色两万六，中性耐脏，做电子结构件的爱用；那条黑增强20%卖两万六的，因为玻纤回收后纤维变短、性能回退，行内直接定三级。透明的琥珀本色再生料，行内都说有价无市，报价单上根本没人挂——干净的本色水口料太少，黄变又压不住。
这里有个朴素逻辑：做外观件、要二次配色的，别指望反复回收的本色料；做内部结构件、不怕黑的，黑色料更划算。颜色选对了，省的是配色成本和换色折腾。
天然V-0和介电是PEI最后的倔强
如果说耐温是PEI的招牌，那阻燃和介电就是它的底线。
PEI分子主链上自带酰亚胺芳环结构，本质上就是阻燃的，不加任何阻燃剂就能过UL94 V-0、甚至5VA，极限氧指数47%到49%。航空内饰那条火焰烟毒的硬规矩，它原生料天然就达标。
介电这一项同样能打：介电强度高，宽频宽温下都稳，体积电阻率压在10的16次方欧·厘米以上。半导体测试座、耐高温连接器、晶圆搬运工具这些要过信号、要绝缘的地方，都认这个脾气。
但有个绕不开的坑：高温加工带来的黄变是不可逆的。你要做浅色、透明件，反复回收的本色料颜色根本压不住。所以行业里再生PEI大多走黑色——用黑把色差盖住，眼不见为净。这就是为什么高端件宁愿选原生本色，再生料老老实实去做黑色遮盖的结构件。阻燃和介电再能打，架不住颜色难看。
四个细分方向，一句话讲清
高耐温级：主打217℃的Tg和200℃上下的热变形温度，做长期耐热的结构件和发动机舱周边件。
高抗冲补纤级：回收后分子量下降冲击变差，靠掺混控制和补纤把缺口冲击拉回来，做要抗摔的壳体。
天然阻燃级：不靠阻燃剂、本色V-0，做对阻燃烟毒有要求的电子电器和运输件。
高介电稳定级：介电强度高、宽温宽频稳，做半导体测试座、耐高温连接器和绝缘件。
写在最后：七条选料口诀
1. 盯耐温：Tg217℃、热变形200℃上下，这是PEI的本钱，别拿普通工程塑料替代；
2. 盯分子量：MFR从原生9升到再生20附近，数字越高链越短、冲击越差；
3. 盯冲击：拉伸基本保留但缺口冲击掉得多，要抗摔的件控制再生料掺混比例；
4. 盯循环：反复挤出3到5次拉伸保持率约八成，别拿多次回收料打主力；
5. 盯颜色：黑色量大价杂、兰色最贵、琥珀本色稀缺，按外观要求选；
6. 盯阻燃介电：本色V-0和高介电是分子给的本钱，阻燃绝缘件认这两项；
7. 盯批次：每车MFR和拉伸值能不能稳在一个区间，比单价重要。
写在最后：再生PEI的性能账，本质是“耐温阻燃介电扛得住、分子量冲击扛不住”这本账。Tg217℃和天然V-0是它天生带的本钱，循环之后照样立得住；分子量是回收环节容易断的那根筷子，掺混掺得准不准，直接决定你量产件裂不裂。宁波市科隆新材料有限公司做再生PEI选型多年，料源走东南亚进口，颜色可控、黑色料源充足、性能稳定，类似测试座、连接器这类要批批一致的案子每年处理几十起，说白了就是帮你把冲击值和颜色在量产之前锁死。
What's the biggest fear when buying recycled PEI?
It's not that it's not heat-resistant enough. This thing has a glass transition temperature of 217°C and a thermal distortion temperature around 200°C, naturally passing UL94 V-0. It's naturally a hardcore player.
The biggest worry is the loss of molecular weight. MFR goes from native 9 to 20, but the parts crack with a drop, and customers crack it with an impact hammer, only to say you cut corners. You can't even argue on the spot—because the heat-resistant material hasn't shrunk, but the recycling process shortens the molecular chain.
Anyone making aerospace interior parts, semiconductor test sockets, or high-temperature resistant connectors—who hasn't been tricked by "looks like good material, but the product is off?"
This article thoroughly explains the performance temperament and color of recycled PEI: which properties remain stable after cycling, which properties are discounted after recycling, and why color directly determines what it can do. Read before placing an order, at least you have a clear plan.
Original ULTEM 1000 base first: density 1.27 grams per cubic centimeter, considered uniform among specialty engineering plastics; tensile strength 105 to 110 MPa, bending modulus around 3.3 gigapa; thermal distortion temperature 198 to 210°C; elongation at break 60%; notch impact 32 to 50 joules per meter, pure material itself somewhat brittle; flame retardant natural V-0 to 5VA, ultimate oxygen index 47% to 49%; High dielectric strength, volume resistivity greater than 10 to the 16th power of ohms·cm.
To put it simply, this thing is naturally heat-resistant, flame-retardant, and insulating—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 up to around 100 MPa, with a reduction of only 5% to 10%. The bad news is that the notch impact loses more than the strength, so ductility collapses accordingly.
Remember this asymmetry: it can withstand tensile performance cycles, but not after impact performance cycles. Choosing recycled PEI is essentially a balance between the two.
Tg217°C is PEI's golden signature
217°C is PEI's financial backbone.
First, let's correct a misconception: PEI is an amorphous material with no melting point, only a glass transition temperature Tg. Unlike crystalline materials, it doesn't suddenly melt at a certain temperature; instead, it gradually softens above 217°C. So it can operate continuously around 170°C year-round, with a thermal deformation temperature between 198 and 210°C.
Compare and you'll understand: the continuous operating temperature of polysulfone PSUs is about 150°C, and PEI is much higher; If you want to talk about the long-term temperature resistance level of PEEK, the price is only one-quarter to one-fifth of PEEK. That's where its 'cost-performance anchor' comes from.
There are also costs: to process this thing, the barrel temperature must be raised to 350 to 410°C, and mold temperature of 135 to 180°C is still mandatory—if the mold drops below 120°C, the part will come out with residual stress, delaying cracking sooner or later. Ordinary injection molding machine barrels simply can't handle this temperature, so you need specialized barrels. This is the flip side of the golden label: the higher the temperature you can withstand, the greater the pain you suffer during processing.
Molecular weight drops faster than hair
The temperature resistance sign is solid, but molecular chains are shorter after one recycling.
The principle is simple: Each PEI melt processing occurs at a high temperature range of 340 to 410°C, combined with oxygen in the air, and the imide and ether bonds are gradually sheared by thermal oxygen aging. Once the chain is shortened, the molecular weight decreases, and the melt flow rate rises—the original reference is 9, and commercially available recycled samples generally rise to around 20. Because the tensile force still relies on inter-chain forces, it is basically maintained around 100 MPa; However, the notch impact and ductility drop more heavily than anyone else's.
The number of cycles also accounts for this: after repeated extruding 3 to 5 times, tensile strength retention drops to about 80%, and the color deepens each time. So industry experience is: don't be greedy for too much recycled to new material; in industrial settings, 25% to 50% is a safe range; For structural parts that need to withstand impact, you need to control the dosage even more.
Dongguan has a client doing semiconductor aging test sockets. Previously, they wanted to buy domestic recycled PEI cheaply. Each batch of MFR floated from 15 to 25, and the socket sleeves were hand-cracked. In three months, two batches cracked, with a return rate as low as 9%. Later, they switched to fixed imported materials from Southeast Asia—black, gray, and blue sprue materials in different colors, with controllable color and minimal impurities. Each truck's measured MFR and tensile values were pinned within a narrow range, the recycled material mixing ratio was matched according to actual measurements, and the return rate was reduced to 0.5% after manual testing for mass-produced parts.
To put it bluntly, imported material color is controllable, black material is abundant, and performance is stable. Once on the mass production line, the test base doesn't have to redo each batch for verification or gamble with the whole batch.
Color is the second face of recycled PEI
The color of recycled PEI directly determines what it can do.
Black is the undisputed main force. Because PEI is processed at high temperatures, molecules inevitably age by heat and oxygen, causing the color to deepen. After repeated recycling, this pigment turns yellow like an old photo left for years. Black has strong hiding power and a wide source—black shells for electronics and electrical parts and industrial parts are mostly black when recycled, so black material is large in quantity and mixed grade, ranging from 22,000 to 25,000 per ton; Black glossy grade is slightly better, 25,000 per ton.
Blue is the most expensive, 38,000 per ton—high requirements for vivid coloring, strict sorting, corresponding to specific downstream color schemes, scarcity premium; Gray 26,000, neutral and stain-resistant, favored by electronic structural parts; That black-enhanced 20% strip sells for 26,000 yuan, because fiberglass shortens after recycling and performance drops, so it's rated as level 3 in the industry. Transparent amber natural color recycled material is said in the industry to be priceless but hard to sell, and no one lists it on the quote—there's too little clean natural color sprue material, and yellowing can't be suppressed.
Here's a simple logic: if you make exterior parts and need secondary coloring, don't expect recycled natural pigments; For internal structural parts that aren't afraid of black, black is more cost-effective. If you choose the right color, you save on color matching costs and the hassle of color changes.
Natural V-0 and dielectric are PEI's last stubborn strengths
If temperature resistance is PEI's trademark, then flame retardancy and dielectric are its bottom line.
PEI molecule backbone has an inherent amimide aromatic ring structure, which is essentially flame-retardant. Without any flame retardants, it can meet UL94 V-0 or even 5VA, with an oxygen index of 47% to 49%. The hard rule for flame poisoning in aerospace interiors is that the virgin material naturally meets the standards.
Dielectric is also impressive: high dielectric strength, stable across wide frequency and temperature, and volume resistivity above 10 to the 16th power of oh·cm. Semiconductor test sockets, high-temperature connectors, wafer handling tools—all areas that require signal passing and insulation—have this temperament. But
has an unavoidable pitfall: yellowing caused by high-temperature processing is irreversible. If you want to make light-colored, transparent parts, the color of recycled natural pigments simply can't be suppressed. That's why most recycled PEI in the industry goes black—using black to cover up color differences, out of sight is out of sight. That's why high-end parts prefer to choose the original color and honestly use recycled materials for black-covered structural parts. No matter how good flame retardant and dielectric are, they can't withstand the unattractive color.
Four subdivisions, explained in one sentence
High Temperature Resistance Grade: Focuses on Tg at 217°C and thermal distortion temperature around 200°C, making long-term heat-resistant structural parts and engine bay peripheral parts.
High Impact Resistance Fiber Repair Grade: After recovery, molecular weight decreases and impact worsens; mixing control and fiber repair pull the notch impact back to create a shell that must be drop-resistant.
Natural flame-retardant grade: No relying on flame retardants or natural V-0, used for electronic and electrical appliances and transportation parts that meet flame retardant and toxic requirements.
High dielectric stability grade: High dielectric strength, wide temperature and frequency stability, used for semiconductor test mounts, high-temperature resistant connectors, and insulating components.
Final note: Seven material selection tips
1. Focus on temperature resistance: Tg 217°C, heat distortion around 200°C, this is PEI's capital, do not replace with ordinary engineering plastics;
2. Watch the molecular weight: MFR rises from 9 for virgin material to around 20 for recycled; the higher the number, the shorter the chains and the worse the impact resistance;
3. Watch the impact: tensile strength is basically retained, but notched impact drops significantly; for parts that need to resist dropping, control the proportion of recycled material;
4. Watch the recycling cycle: repeated extrusion 3 to 5 times keeps about 80% of tensile strength; don’t use heavily recycled material as the main material;
5. Watch the color: black has large quantity and variable price, blue is the most expensive, amber natural color is scarce, choose according to appearance requirements;
6. Watch flame retardancy and dielectric properties: natural-colored V-0 and high dielectric strength are inherent molecular properties; flame-retardant insulating parts should meet these two requirements;
7. Watch the batch: whether MFR and tensile values for each shipment stay within a stable range is more important than unit price.
Finally: The performance account of recycled PEI essentially boils down to "high temperature, flame retardancy, and dielectric strength hold up, but molecular weight and impact don’t." Tg 217℃ and natural V-0 are innate assets, still maintained after recycling; molecular weight is the bamboo stick that easily breaks during the recycling process, and whether the blending is precise directly determines if your mass-produced parts will crack. Ningbo Kelong New Material Co., Ltd. has years of experience in selecting recycled PEI. The material is sourced from Southeast Asia, color controllable, abundant black material, stable performance. For projects like test sockets and connectors that require batch-to-batch consistency, they handle dozens of cases each year. Simply put, they help you lock in the impact value and color before mass production.
