76 PA66 与 PPS：耐高温与耐化学的两个上限怎么分
一、为什么放在一起比
PA66 和 PPS 是工程塑料里耐高温方向的两大料：
PA66：脂肪族尼龙主力，耐温 120-150℃。
PPS：聚苯硫醚，半结晶，耐温 200-240℃。
PPS 是"耐温 + 耐化学"的双重强者，比 PA66 高一档。但 PPS 不是 PA66 的"升级版"——它有自己的位置、自己的边界。
发动机舱里，PA 与 PPS 的分界线常常就在一个阀的距离。有个客户做排气再循环阀，阀体附近长期一百八十度，原用 PPA 已经是 PA 族的顶配，仍然在两年质保期出现老化粉化。
换 PPS 后，温度这一页翻过去了，新的功课是加工：PPS 料温高、模温高，模具的排气与保温要重做。
客户总结得很到位：PPS 不是更贵的 PA，是另一套工艺体系，换它之前先问自己的车间答不答应。
温度把边界划清，工艺把门槛立起，两关都过，PPS 才是选项。
二、化学结构差异
PA66：己二胺 + 己二酸，半结晶。
PPS：对苯 + 硫 + 苯环为主链，半结晶。
PPS 主链中"苯环 + 硫醚键"的结构带来三个差异：
① 链段刚性极高
苯环让链段非常"硬"，玻璃化温度 85-90℃，但耐温更高（200-240℃）。PA66 的玻璃化温度 50-65℃，长期耐温 120-150℃。
② 极性低、耐化学性极佳
苯环 + 硫醚键的极性比 PA66 的酰胺基低得多。PPS 在几乎所有溶剂中都稳定——醇、酮、酯、酸、碱、盐水、燃油等。这是 PPS 的核心优势。
③ 流动性与脆性
PPS 流动性受限于高熔点，且 PPS 本身偏脆。PPS 通常要用玻纤 + 填料补强，纯 PPS 极少用。
三、关键性能对照
| 指标 | PA66 | PPS（GF40 典型） | 差异方向 |
|---|
| 熔点（℃） | 255-265 | 280-290 | PPS 略高 |
| 玻璃化温度（℃） | 50-65 | 85-90 | PPS 高约 30℃ |
| 长期工作温度上限（℃） | 120-150 | 200-240 | PPS 高约 80℃ |
| 耐化学性 | 中（酰胺基敏感） | 极佳（几乎所有溶剂稳定） | PPS 远远胜 |
| 拉伸强度（GF 后，MPa） | 170-200 | 170-200 | 接近 |
| 弯曲模量（GF 后，GPa） | 8-10 | 12-15 | PPS 略高 |
| 缺口冲击（kJ/m²） | 12-18 | 6-10 | PA66 高一档 |
| 吸水率（%） | 2.0-2.5 | 0.02-0.05 | PPS 极低 |
| 焊接强度 | 中 | 高 | PPS 略强 |
| 注塑流动性 | 中 | 中偏低 | PA6 好 |
| 玻纤协同 | 高 | 极高 | PPS-GF 优势更大 |
| 阻燃性 | 加阻燃可达 V0 | 本身 V0 | PPS 天然阻燃 |
| 单价（普通级，参考） | 1.0× | 4.0-6.0× | PPS 显著贵 |
四、PPS 胜在何处
① 长期 200℃ 以上工作
汽车涡轮壳体、引擎周边、PTC 加热器、航空连接器——这些 200℃ 以上的工况，PPS 是少数塑料能稳的料。PA66 在 200℃ 已分解。
② 极端耐化学
燃油、机油、冷却液、刹车液、洗涤剂、醇类、酸、碱——PPS 几乎都不腐蚀。这是为什么汽车油路、化工设备、医疗器械选 PPS。
③ 天然阻燃
PPS 极限氧指数（LOI） 40-50%，不燃。不加阻燃剂就达 V0。这是 PPS 在电子电气领域的"免费优势"。
④ 极低吸水率
PPS 0.02-0.05% 的吸水率，几乎不受湿度影响。精密件、户外件用 PPS 尺寸稳定性极佳。
⑤ 高刚性 + 高耐温 + 阻燃
PA66-GF30 能做到高刚性 + 耐 130℃，但PA66 不可能在 200℃ 长期耐温。PPS-GF40 才是兼具的方案。
五、PA66 胜在何处
① 韧性 + 抗冲击
PPS 偏脆，缺口冲击比 PA66-GF30 低一档。低温跌落、冲击工况 PA66-GF 更稳。
② 价格优势
PA66 单价是 PPS 的 1/4 到 1/6。大批量价格敏感场合，PA66 是大宗选择。
③ 焊接组合件
PPS 焊接强度好，但具体工艺比 PA66 苛刻（流动性弱、模温要求高）。PA66 焊接工艺成熟度比 PPS 好。
④ 流动性与复杂件
PPS 因高熔点、高粘度，复杂件、薄壁、长流程件灌得满 PA66 容易。PPS 容易短射。
⑤ 供应与国产替代
PA66 全球供应充足、国产料稳定。PPS 国产料仍在追赶，多数项目依赖进口（DIC、东丽、索尔维、雪佛龙菲利普斯等）。
六、两者都不擅长的工况
① 长期 ≥240℃
PPS 也不够。走 PEEK（聚醚醚酮）、PA46 + 改性、PI（聚酰亚胺）。
② 高韧性 + 200℃
PPS 脆，达不到 200℃ 也高韧性。这种工况要走 PEI（聚醚酰亚胺）或 PEEK。
③ 透明件
两者都不透明。透明件走 PC、PMMA、PEI 等。
④ 食品级、医疗级（直接接触）
PPS 在食品级配方上还在追赶。食品级透明件走 PP、PE、PA12 等。
七、四条搭配或分工组合
① 油路系统
油路主件用 PPS-GF40（耐油 + 耐温），卡扣连接件用 PA66-GF30（韧性 + 卡扣力）。汽车油轨、油泵壳体常用这种组合。
② 高温连接器
外骨架 PA66-GF30（结构 + 韧性），内骨架 PPS（耐温 + 阻燃 + 焊线）。高端连接器分层用两料。
③ 微波炉 / 烤箱内部件
PPS 天然阻燃 + 耐温，是微波炉转盘支架、烤箱内支架常用料。这种"塑料件 + 高温"的典型场景，PPS 几乎独占。
④ 化工阀门
PPS 在酸碱盐腐蚀性流体中是首选。这是 PPS 在化工设备的主要位置。
八、四个延伸判断（耐高温 + 耐化学方向通用）
判断一：耐温 + 耐化学是同一族塑料的两个方向。PPS、PEEK、PEI、PPA 这一族都同时具备这两点。但 PA66 / PA6 / PA46 这一族在这一项就输了。当你需要同时耐温与耐化学，跳出 PA 系列思考。
判断二：PPS 的天然阻燃是"零成本优势"。PA66-GF30 + 阻燃可以达到 V0，但加了阻燃剂后流动性再降一档、性能也降一档。PPS 不用加阻燃剂，这是它在电气应用中选材时的"免费"优势。
判断三：低吸水率是 PPS 在精密件的优势。PA66 吸水 2.5%，三个月湿态尺寸变化明显。PPS 几乎不吸水，精密件用 PPS 更稳。
判断四：PPS 不是 PA66 的替代品。它们是不同档的两料。当你真的需要 PPS 时，PA66 怎么加玻纤、加阻燃、加耐温改性都到不了那个位置。
九、边界声明
| 工况 | 建议 |
|---|
| 长期 ≤150℃ | PA66-GF30 / PA66-GF35 |
| 长期 150-200℃ | PPA / PA6T / PA9T |
| 长期 200-240℃ | PPS-GF40 |
| 长期 ≥240℃ | PEEK / PEI |
| 极端耐化学 | PPS / PEEK |
| 高韧性 + 高耐温 | PA66-GF30（耐温到 150℃） |
| 焊接组合件 + 耐温 | PPS-GF30 / PA66-GF30（看温度） |
| 食品级（直接接触） | PA12 / PE / PP |
| 阻燃 + 耐温 + 强度 | PPS（天然阻燃） |
附：两个选型实例
实例一：汽车涡轮增压器壳体
工况：长期 200℃；承受高循环载荷；耐机油。
推演：
200℃ → PA66 出局，PA46 在边界
高循环 → PPS 比 PPA/PA46 更稳
耐机油 → PPS 极佳
结论：PPS-GF40。
实例二：户外大电流连接器
工况：长期 130℃；电绝缘；阻燃；高电流通过。
推演：
130℃ → PA66-GF30 已够
阻燃 → PA66-GF30 + 阻燃 vs PPS（天然）
电绝缘 → 两者都过
经济 → PA66 显著便宜
结论：PA66-GF30 + 阻燃。如果客户规范指定阻燃不加 + 长期稳定性更高，PPS 更好。
行业感：耐温的决策层，比想象的还要高。 我们见过一个做汽车涡轮壳体的项目，最初方案是 PA66-GF35 + 阻燃，价格 80 元/kg。但工程师发现实际长期 180℃，PA66-GF35 在 180℃ × 2000 小时开始脆化。客户拒绝用 PA46（强度不够），改用了 PPS-GF40，价格 380 元/kg。单一料贵了 4 倍，但整车保修期延长 1.5 年，售后成本降低 30%。 "贵"有时候是"省"的别名——这要看怎么算账。
一个变频器端子座的选择
起点是变频器功率端子座，客户在阻燃 PA66 与 PPS 之间摇摆。
潜伏期没出现，因为选型阶段就做了加速老化：高温高湿下 PA66 阻燃体系的电痕化趋势更明显，端子间距又小。
结算方案：端子座用 PPS，外壳与走线槽保持阻燃 PA66，成本只涨在刀刃上。
这台变频器跑过了最严苛的认证批次。客户说，分件分得细，认证就顺。
PA 与 PPS 的对比会，三个追问。
追问一：长期温度过 150℃ 了吗？ 过了，PA 族基本退场，看 PPS。
追问二：接触化学介质吗？ 强腐蚀工况 PPS 近乎免疫。
追问三：车间能伺候它吗？ 料温三百度上下、模温一百四起步，设备先过关。
延伸：四步速判（PA66 vs PPS 方向）
四步把"耐温耐化"的对比压成可走动作：
第一步：量温度档位。≤150℃ → PA66-GF30；150-200℃ → PPA/PA6T；200-240℃ → PPS-GF40；≥240℃ → PEEK。
第二步：量化学品。PPS 在几乎所有溶剂中稳定（醇、酮、酯、酸、碱、盐水、燃油）。接触这些介质且 ≥150℃，PPS 是必选。
第三步：问"阻燃要不要免费"。PPS 天然阻燃（不加阻燃剂即达 V0），PA66-GF 必须加阻燃剂。电气件方案里 PPS 优势明显。
第四步：算模具与加工。PPS 加工窗口比 PA66 窄，模具成本高 30-80%。复杂件、薄壁、长流程件，PA66 占优。
这四条之外还有"分工"做法：油路主件 PPS + 卡扣连接件 PA66-GF30，这在汽车油轨、制动系统中常见。
实战：三步走
第一步：温度档位直接分线。≤150℃ 选 PA66-GF30，150-200℃ 选 PPA / PA6T，200-240℃ 选 PPS-GF40，≥240℃ 选 PEEK。
第二步：化学品档位再分线。接触醇/酮/酸/碱/燃油 —— PPS 是塑料里最稳的方案。
第三步：阻燃免费性。PPS 天然阻燃（不加阻燃剂就达 V0）——电气件 PA66 + 阻燃剂 不如 PPS 一站式方案稳。
关键提示
PPS 的天然阻燃 + 耐化学性让它在汽车涡轮、油路、化工阀门、5G 介质件等场景成为必选。但模具成本 + 加工费是 PA66 的 1.5-2 倍。
短期项目用 PPS 划不来，长期高利润项目用 PPS 才能省心。
工程备忘
PPS 在汽车油路、涡轮、化工阀门、5G 介质件几乎不可替代，但价格与模具成本是 PA66 的 1.5-2 倍。短期项目不划算，长期项目省心。
行业感
PPS 的核心竞争力是"耐温 + 耐化学 + 天然阻燃"三项同时具备，PA66 怎么加玻纤、改性都到不了。这是为什么汽车涡轮、化工阀门、高端连接器选 PPS。
收尾补一张三问三答。
| 高频问题 | 一句话回答 |
|---|
| PPS 比 PA 贵多少？ | 两到四倍，按牌号与行情 |
| 韧性谁好？ | PA 好，PPS 偏刚脆 |
| 能加玻纤补韧吗？ | 补刚性行，补韧性有限 |
| 什么场合必须 PPS？ | 长期 150℃ 以上或强腐蚀 |
再补一个反向案例。
有个项目听说 PPS 耐化学好，把常温下接触清洗剂的齿轮换了 PPS。齿轮没坏，坏的是账：单件贵三倍，韧性反而不如原 PA66 增韧，装配敲击断了几根轴。清洗剂对 PA66 增韧体系本来就不构成威胁。
为不存在的风险付三倍的钱，是选型里最常见的冤枉账。
数字的来历：两三个为什么
PPS 为什么近乎免疫化学介质？它的分子链由苯环与硫原子交替构成，结构致密规整，结晶后几乎没有可供小分子钻营的空隙。强酸强碱以外的绝大多数介质，都很难在它身上打开缺口。
发动机舱、化工厂、高温水路，这些位置留给 PPS 不是因为贵，是因为别的料确实站不住。
PPS 为什么偏脆？刚性链结晶度高，韧性储备天然有限，加玻纤补的是刚性不是韧性。需要韧性的位置留在 PA 侧，需要耐温耐化学的位置交给 PPS——分件的思路，比换料的思路省钱也省事。
实操清单：高温耐蚀件六动作
长期 150℃ 定为红线，过线直接看 PPS
车间设备先盘点：料温、模温、干燥全套够不够
模具排气与保温单独预算，不与 PA 模混用经验
介质的浓度与温度逐项记录，交给供应商评级
降本先分件：高温区 PPS，低温区 PA66
韧性要求高的位置留在 PA 侧，别硬扛
PPS 的项目，一半功夫在选型前。设备、模具、介质三张清单列清楚，立项会就能开出结论，而不是开出问题。
速判手册：PPS 上场的三个信号
| 信号 | 说明 |
|---|
| 长期 150℃ 以上 | PA 体系整体退场 |
| 强腐蚀介质长期存在 | PPS 结构近乎免疫 |
| 电气要求叠加高温 | PPS 的 CTI 与耐电弧占优 |
三个信号在发动机舱与变频器里经常同时出现，这也是 PPS 在这两个领域几乎垄断的原因。值得注意的是第三个信号：很多人只盯温度，忘了电气。
端子座、传感器座这类件，耐电痕化与耐电弧的数据在 PPS 上明显更漂亮，为认证少跑的弯路，价值不比耐温低。
工艺门槛再强调一遍细节：PPS 的模温要求高，低于推荐值结晶不足，件的后收缩会让尺寸在几天内继续漂。有客户用打 PA 的模具直接试 PPS，模温机功率不够，量产后三天尺寸全漂，停线整改。
模温这件事在 PPS 上不是参数是门槛，设备清单先过，再谈选型。
韧性短板的补救还有一个思路是复合结构：PPS 做外壳骨架，应力集中的卡扣位用金属嵌件或二次注塑的弹性体包覆。成本可控，风险分散，比单纯加增韧改性更稳。结构设计与材料选择从来不是两条路，好方案都长在两条路的交汇处。
PPS 项目的时间账也要提前算：认证与送检周期长，材料一旦选定就锁死，中途换料的代价极大。所以立项阶段的冗余设计很重要——同一位置准备两个可互换的牌号，主选与备选都过基础验证，一旦主选出现供应波动，备选顶上不动模具。
有客户的 PPS 件经历过一次上游事故，靠备选牌号顶了八个月，产线一天没停。预案的价值平时看不见，出事那天就是全部。
结语
PA66 和 PPS 的分工，是"耐中温 + 经济"与"耐高温 + 高价"的对照。
PA66 是结构主力：耐温 130-150℃，经济、韧性、焊接、玻纤——大多数工业件主力。
PPS 是耐高温上场：耐温 200-240℃、耐化学、阻燃、尺寸稳定——涡轮壳体、化工设备、高端连接器。
选型的起点不是"哪个更贵更好"，而是"我这个件长期温度 + 是否耐化学"。 同时卡在这两点上，PPS 才是正确选项；只卡在耐温上，PA66-GF 也够用。
76 PA66 and PPS: How to differentiate the two extremes of high temperature resistance and chemical resistance
1. Why putting them together is better than
PA66 and PPS are the two major high-temperature resistant materials in engineering plastics:
PA66: The main aliphatic nylon, resistant to temperatures of 120-150°C.
PPS: Polyphenylene sulfide, semi-crystalline, temperature resistant 200-240°C.
PPS is a dual powerhouse of 'temperature resistance and chemical resistance,' one level higher than PA66. But PPS is not an 'upgraded version' of PA66 — it has its own position and its own boundaries.
In the engine compartment, the boundary between PA and PPS is often just the distance of one valve. A customer was making an exhaust gas recirculation valve, and the area near the valve body was constantly at 180 degrees. The original PPA, already the top of the PA family, still experienced aging and powdering within the two-year warranty period.
After switching to PPS, the temperature page was turned over. The new task is processing: PPS material has a high temperature and the mold temperature is high, so the mold's venting and insulation need to be redone.
The client summarized it accurately: PPS is not a more expensive PA, it is a completely different processing system. Before switching to it, ask your workshop if they are okay with it.
Temperature defines the boundaries, the process sets the threshold, only if both are met, PPS becomes an option.
2. Differences in Chemical Structure
PA66: hexamethylenediamine and adipic acid, semi-crystalline.
PPS: The main chain consists of a benzene-sulfur-benzene ring, semi-crystalline.
The structure of 'benzene ring and thioether bond' in the PPS main chain brings three differences:
① The chain segment is extremely rigid
The benzene ring makes the chain segment very 'rigid', with a glass transition temperature of 85-90°C, but a higher heat resistance (200-240°C). PA66 has a glass transition temperature of 50-65°C and a long-term heat resistance of 120-150°C.
② Low polarity, excellent chemical resistance
The polarity of the benzene ring–thioether bond is much lower than the amide group in PA66. PPS is stable in almost all solvents—alcohols, ketones, esters, acids, bases, saline, fuels, etc. This is the core advantage of PPS.
③ Liquidity and Fragility
The fluidity of PPS is limited by its high melting point, and PPS itself is brittle. PPS is usually reinforced with glass fiber fillers; pure PPS is rarely used.
3. Key Performance Comparison
| Indicator | PA66 | PPS (GF40 Typical) | Direction of difference |
|---|
| Melting point (°C) | 255-265 | 280-290 | PPS slightly high |
| Glass transition temperature (°C) | 50-65 | 85-90 | PPS approximately 30℃ high |
| Maximum Long-Term Operating Temperature (°C) | 120-150 | 200-240 | PPS high about 80℃ |
| Chemical resistance | Medium (amide-sensitive) | Excellent (stable in almost all solvents) | PPS far surpasses |
| Tensile Strength (after GF, MPa) | 170-200 | 170-200 | approach |
| Flexural modulus (after GF, GPa) | 8-10 | 12-15 | PPS slightly high |
| Notch Impact (kJ/m²) | 12-18 | 6-10 | PA66 high grade |
| Water Absorption (%) | 2.0-2.5 | 0.02-0.05 | PPS very low |
| Welding strength | middle | Tall | PPS is slightly stronger |
| Injection molding flowability | middle | Slightly below average | PA6 is good |
| Glass fiber collaboration | Tall | Extremely high | PPS-GF has greater advantages |
| Flame retardancy | Flame retardant can reach V0 | Itself V0 | PPS Naturally Flame Retardant |
| Unit price (standard grade, reference) | 1.0× | 4.0-6.0× | PPS is significantly more expensive |
4. Where PPS Wins
① Long-term operation above 200℃
Automotive turbocharger housings, engine components, PTC heaters, aerospace connectors—under these conditions above 200°C, PPS is one of the few plastics that can remain stable. PA66 decomposes at 200°C.
② Extremely chemical-resistant
Fuel, engine oil, coolant, brake fluid, detergents, alcohols, acids, bases—PPS is hardly corroded by any of these. This is why PPS is chosen for automotive fuel lines, chemical equipment, and medical devices.
③ Naturally flame-retardant
PPS has a limiting oxygen index (LOI) of 40-50%, and is non-combustible. It can reach V0 without adding flame retardants. This is PPS's 'free advantage' in the electronics and electrical field.
④ Extremely low water absorption rate
PPS has a water absorption rate of 0.02-0.05%, which is almost unaffected by humidity. PPS offers excellent dimensional stability for precision parts and outdoor components.
⑤ High rigidity High temperature resistance Flame retardant
PA66-GF30 can achieve high rigidity and withstand 130℃, but PA66 cannot withstand 200℃ for long-term use. PPS-GF40 is the solution that combines both.
5. Where PA66 Excels
① Toughness Impact resistance
PPS is relatively brittle, and its notch impact strength is one level lower than PA66-GF30. Under low-temperature drop and impact conditions, PA66-GF is more stable.
② Price Advantage
The unit price of PA66 is 1/4 to 1/6 of PPS. In scenarios sensitive to large-volume pricing, PA66 is the bulk choice.
③ Welded assembly
PPS has good welding strength, but its specific process is more demanding than PA66 (poor fluidity, high mold temperature requirements). The welding process maturity of PA66 is better than PPS.
④ Liquidity and complex parts
Due to its high melting point and high viscosity, PPS is easy to underfill complex parts, thin-walled parts, and long-process parts compared to PA66. PPS is prone to short shots.
⑤ Supply and Domestic Substitution
PA66 has ample global supply and stable domestic materials. Domestic PPS is still catching up, and most projects rely on imports (DIC, Toray, Solvay, Chevron Phillips, etc.).
6. Operating conditions in which neither is proficient
① Long-term ≥240℃
PPS is also not enough. Move to PEEK (polyether ether ketone), modified PA46, PI (polyimide).
② High toughness 200℃
PPS is brittle and can't reach 200℃ but has high toughness. For this kind of working condition, you need to use PEI (polyetherimide) or PEEK.
③ Transparent part
Both are opaque. Transparent parts go through PC, PMMA, PEI, etc.
④ Food grade, medical grade (direct contact)
PPS is still catching up in food-grade formulations. Food-grade transparent parts use PP, PE, PA12, etc.
7. Four pairings or divisions of labor combinations
① Oil Circuit System
The main components of the oil circuit use PPS-GF40 (oil-resistant, heat-resistant), and the snap-fit connectors use PA66-GF30 (tough, snap-fit strength). This combination is commonly used in automotive fuel rails and oil pump housings.
② High-temperature connector
Exoskeleton PA66-GF30 (structural toughness), internal skeleton PPS (temperature resistant, flame retardant, weld lines). High-end connectors use two materials in layers.
③ Microwave / Oven Internal Components
PPS is naturally flame-retardant and temperature-resistant, and it is commonly used for microwave turntable supports and oven inner supports. In such typical 'plastic parts for high-temperature' scenarios, PPS is almost the sole choice.
④ Chemical valves
PPS is the first choice in acidic, alkaline, and saline corrosive fluids. This is the main position of PPS in chemical equipment.
VIII. Four Extended Judgments (High Temperature Resistance, General Use in Chemical Direction)
Judgment 1: Temperature Resistance Chemical Resistance are two directions of the same family of plastics. PPS, PEEK, PEI, and PPA all have both points. But PA66 / PA6 / PA46 lose in this aspect. When you need both temperature and chemical resistance, think beyond the PA series.
Judgment Two: The inherent flame retardancy of PPS is a 'zero-cost advantage.' PA66-GF30 can achieve V0 flame retardancy, but after adding flame retardants, its flowability decreases by a level, and its performance also drops by a level. PPS does not require the addition of flame retardants, which is its 'free' advantage when selecting materials for electrical applications.
Judgment Three: Low water absorption is an advantage of PPS in precision parts. PA66 absorbs 2.5% water, and its dimensional changes in the wet state are significant over three months. PPS hardly absorbs water, making it more stable for precision parts.
Judgment Four: PPS is not a substitute for PA66. They are two different grades of materials. When you really need PPS, no amount of adding fiberglass, flame retardants, or heat-resistant modifications to PA66 will reach that level.
9. Boundary Statement
| Operating condition | Suggestion |
|---|
| Long-term ≤150℃ | PA66-GF30 / PA66-GF35 |
| Long-term 150-200℃ | PPA / PA6T / PA9T |
| Long-term 200-240℃ | PPS-GF40 |
| Long-term ≥240℃ | PEEK / PEI |
| Extremely chemical-resistant | PPS / PEEK |
| High toughness High temperature resistance | PA66-GF30 (temperature resistant up to 150℃) |
| Welded Assembly Temperature Resistant | PPS-GF30 / PA66-GF30 (depending on temperature) |
| Food grade (direct contact) | PA12 / PE / PP |
| Flame retardant Temperature resistant Strength | PPS (naturally flame-retardant) |
Appendix: Two selection examples
Example 1: Car turbocharger housing
Working conditions: long-term 200℃; subjected to high cyclic loads; resistant to engine oil.
Deduction:
200℃ → PA66 is out, PA46 is at the boundary
High cycle → PPS is more stable than PPA/PA46
Oil-resistant → PPS Excellent
Conclusion: PPS-GF40.
Example 2: Outdoor High-Current Connector
Working conditions: long-term 130°C; electrical insulation; flame retardant; high current passing through.
Deduction:
130℃ → PA66-GF30 is sufficient
Flame Retardant → PA66-GF30 Flame Retardant vs PPS (Natural)
Electrical insulation → Both pass
Economical → PA66 is significantly cheaper
Conclusion: PA66-GF30 is flame retardant. If the customer specifications do not require flame retardancy, long-term stability is higher, and PPS is better.
Industry Insight: The decision-makers on temperature resistance are even more advanced than expected. We encountered a project making automotive turbocharger housings. The initial plan was PA66-GF35 flame-retardant, priced at 80 RMB/kg. However, engineers found that at a long-term 180°C, PA66-GF35 started to become brittle after 2000 hours. The client refused to use PA46 (insufficient strength) and switched to PPS-GF40, priced at 380 RMB/kg. A single material became 4 times more expensive, but the vehicle warranty period was extended by 1.5 years, and after-sales costs were reduced by 30%. 'Expensive' is sometimes just another word for 'saving'—it all depends on how you calculate the numbers.
Selection of a Inverter Terminal Block
The starting point is the power terminal of the inverter, and the customer is wavering between flame-retardant PA66 and PPS.
No incubation period appeared because accelerated aging was done during the selection phase: under high temperature and high humidity, the electrical tracking tendency of the PA66 flame-retardant system is more obvious, and the terminal spacing is small.
Settlement Plan: Use PPS for the terminal block, keep the housing and wiring duct in flame-retardant PA66, with cost increases only at the critical points.
This inverter has gone through the most rigorous certification batches. The customer said that the more finely the parts are divided, the smoother the certification process.
Comparison meeting between PA and PPS, three follow-up questions.
Follow-up question 1: Has the long-term temperature exceeded 150°C? Yes, the PA series has basically exited, look at PPS.
Follow-up Question 2: Does it come into contact with chemical media? PPS is almost immune to highly corrosive conditions.
Follow-up Question 3: Can the workshop handle it? Material temperature around 300 degrees, mold temperature starting from 140, the equipment passes first.
Extension: Four-step speed judgment (PA66 vs PPS direction)
Four-step press-and-run "temperature and chemical resistance" comparative action:
Step one: measure the temperature range. ≤150℃ → PA66-GF30； 150-200℃ → PPA/PA6T； 200-240℃ → PPS-GF40； ≥240℃ → PEEK。
Step 2: Quantify chemicals. PPS is stable in almost all solvents (alcohols, ketones, esters, acids, alkalis, brine, fuel). When exposed to these media and ≥ 150°C, PPS is essential.
Step 3: Ask, "Does flame retardant require free treatment?" PPS is naturally flame-retardant (without flame retardant it reaches V0), while PA66-GF must have flame retardant added. PPS has obvious advantages in electrical component solutions.
Step 4: Calculate molds and processing. PPS has a narrower processing window than PA66, and mold costs are 30-80% higher. For complex parts, thin-walled, and long-process parts, PA66 has the advantage.
Besides these four points, there is also a "division of labor" approach: main oil circuit PPS + snap-fit connector PA66-GF30, which is common in automotive oil rails and brake systems.
Practical: Three steps
Step 1: Direct wire separation at temperature levels. ≤ 150°C, select PA66-GF30; at 150-200°C, choose PPA/PA6T; at 200-240°C, choose PPS-GF40; ≥ 240°C, choose PEEK.
Step 2: Further rewire at the chemical level. Contact alcohol/ketones/acids/alkalis/fuel — PPS is the most stable solution among plastics.
Step 3: Flame-retardant-free. PPS is naturally flame-retardant (reaching V0 without flame retardant)—electrical parts PA66 + flame retardant are not as stable as PPS's one-stop solution.
Key Point
PPS Its natural flame retardancy + chemical resistance makes it a must-have choice for automotive turbines, fuel lines, chemical valves, 5G dielectric components, and more. However, mold cost + processing fees are 1.5-2 times higher than PA66.
PPS is not cost-effective for short-term projects; only PPS for long-term high-profit projects can save the trouble.
Engineering Memo
PPS is almost irreplaceable for automotive oil circuits, turbines, chemical valves, and 5G dielectric parts, but the price and mold cost are 1.5-2 times higher than PA66. Not cost-effective for short-term projects, but worry-free for long-term projects.
Industry Sens
PPS's core competitiveness is having "temperature resistance + chemical resistance + natural flame retardancy" all at once. No matter how you add fiberglass or modify PA66, it can't be achieved. That's why automotive turbines, chemical valves, and high-end connectors choose PPS.
Closing with a three-question, three-answer post.
| High-frequency questions | One-sentence answer |
|---|
| PPS How much more expensive is PA? | Two to four times, by grade and market price |
| Which has better toughness? | PA Okay, PPS tends to be rigid and brittle . |
| Can fiberglass be added for toughness? | Rigidity is fine, toughness is limited |
| In what situations is PPS necessary? | Long-term above 150°C or strong corrosion |
Here's another reverse case.
There's a project I heard PPS has good chemical resistance, so they replaced the gear that came into contact with cleaning agents at room temperature with PPS. The gears weren't broken, but the problem was: the single piece was three times more expensive, but its toughness was actually less than the original PA66 for toughness, and a few shafts were broken during assembly. Cleaning agents do not pose a threat to PA66 toughening systems to begin with.
Paying three times the price for nonexistent risks is the most common misfortune in product selection.
The Origin of the Number: Two or Three Why
PPS Why is it almost an immunochemical medium? Its molecular chain is made up of alternating benzene rings and sulfur atoms, with a dense and regular structure. Once crystallized, there are almost no gaps for small molecules to drill. Most media other than strong acids and bases find it difficult to break through it.
Engine compartment, chemical plants, high-temperature waterways—these spots are reserved for PPS not because they're expensive, but because other materials simply can't hold up.
PPS Why is it so brittle? Rigid chains have high crystallinity, and toughness reserves are naturally limited. Adding glass fiber compensates for rigidity, not toughness. Positions requiring toughness remain on the PA side, while positions needing temperature and chemical resistance are left to PPS—the split-part approach saves money and effort compared to material replacement.
Practical Operation Checklist: Six actions for high-temperature corrosion-resistant parts
Long-term 150°C is set as the red line, crossing the line directly depends on PPS
Workshop equipment inventory first: material temperature, mold temperature, and drying completeness are sufficient
Mold venting and insulation should be budgeted separately, not mixed with PA mold experience
Record media concentration and temperature item by item, and submit to supplier rating
Cost reduction first parts: high-temperature zone PPS, low-temperature zone PA66
High toughness requirements should be left on the PA side, don't force
PPS projects, half the effort is before selection. If the equipment, mold, and medium are clearly listed, the project initiation meeting can draw conclusions, not problems.
Quick Judgment Manual: The three signals used in PPS
| Signal | Explanation |
|---|
| Long-term system exit above 150° C | PA |
| Strongly corrosive media persist long-term | PPS structure is almost immune |
| Electrical requirements combined with | PPS high-temperature CTI and arc resistance are dominant |
Three signals often appear simultaneously in engine compartments and frequency converters, which is why PPS almost monopolizes these two fields. The third signal worth noting is: many people only focus on temperature and forget about electrical equipment.
For components like terminal and sensor sockets, the anti-trace and arc resistance data for PPS are clearly better, avoiding detours for certification, and its value is no less than temperature resistance.
Process threshold emphasizes details again: PPS requires high mold temperature, below the recommended value, resulting in insufficient crystallization. Post-shrinkage of parts causes the dimensions to continue drifting within a few days. Some customers tested PPS directly with molds that applied PA, but the mold temperature controller's power was insufficient. After three days of mass production, the dimensions fully blew, requiring shutdown for rectification.
Mold temperature is not a parameter but a threshold in PPS; the equipment list should be reviewed first, then model selection will be discussed. Another approach to remedying
toughness shortcomings is composite structures: PPS as the shell framework, with stress concentration fasteners coated with metal inserts or secondary injection molding elastomers. Cost controllable, risk dispersed, and more stable than simple toughening modification. Structural design and material selection are never two paths; good solutions always grow at their intersection.
PPS Project timeline must also be calculated in advance: certification and inspection cycles are long, materials are locked once selected, and mid-process material changes are costly. Therefore, redundancy design during project initiation is very important—prepare two interchangeable grades in the same location, with both main and backup options undergoing basic verification. If supply fluctuates in the primary selection, the backup is fixed on top of the mold.
A client's PPS parts experienced an upstream accident and managed to hold up with alternative grades for eight months, with the production line never stopping for a day. The value of the contingency plan is usually invisible, but on the day of the accident, it was everything.
Conclusion
The division of labor between PA66 and PPS is a contrast between "medium-temperature resistant and economical" and "high-temperature resistant and expensive."
PA66 is the structural mainstay: temperature resistance 130-150℃, economical, tough, weldable, fiberglass-reinforced — the main choice for most industrial parts.
PPS comes into play for high-temperature resistance: temperature resistance 200-240℃, chemical resistance, flame retardant, dimensional stability — used in turbine housings, chemical equipment, and high-end connectors.
The starting point for material selection is not "which is more expensive and better," but "can this part withstand long-term temperature and chemical exposure." Only when it hits both points is PPS the correct choice; if only temperature resistance is a concern, PA66-GF is sufficient.
