Nylon and polypropylene are the two highest-volume engineering thermoplastics — but they occupy opposite ends of the performance spectrum. Nylon offers 3-4x the tensile strength, double the heat resistance, and far better wear properties. Polypropylene wins on cost (2-3x cheaper by weight) and chemical resistance.
| 財產 | Nylon 6 (PA6) | 聚丙烯 (PP) |
|---|---|---|
| 拉伸強度 | 70-80 MPa | 25-35 MPa |
| 彎曲模量 | 2,500-3,000 MPa | 1,000-1,500 MPa |
| Continuous Use Temp | 100-120°C | 80-100°C |
| 耐化學性 | Moderate (acids attack nylon) | Excellent (resists most chemicals) |
| Material Cost | $3-5/kg | $1-2/kg |
When PP Is the Right Choice
Polypropylene is the material of choice for living hinges (thin flexible joints that flex thousands of times), chemical storage tanks and containers, and disposable or low-cost consumer products. Its fatigue resistance in flexure is unmatched — a well-designed PP living hinge survives millions of flex cycles where nylon would fail in hundreds. PP is also FDA-compliant for food contact applications with fewer restrictions than nylon.
When Nylon Wins
Nylon dominates applications requiring mechanical strength, wear resistance, and elevated temperature performance: gears, bearings, structural brackets, automotive under-hood components. Nylon’s self-lubricating properties make it ideal for sliding and rotating applications. Glass-filled nylon (PA66-GF30) achieves tensile strengths exceeding 180 MPa — competing with die-cast zinc while weighing 40% less.
常見問題
Is nylon always better than polypropylene?
No. For living hinges, chemical tanks, and low-cost disposable products, PP outperforms nylon. Nylon’s moisture absorption also makes it a poor choice for wet environments where PP’s hydrophobic nature is an advantage. Select the material based on requirements, not a hierarchy.
Can polypropylene gears replace nylon gears?
Not in most cases. PP’s lower strength, lower hardness, and higher wear rate make it unsuitable for gears carrying significant torque. PP finds use in low-load timing pulleys and light-duty applications, but acetal or nylon remain the standard plastic gear materials.
Which is cheaper to injection mold?
PP is both cheaper in material cost and easier to mold (lower melt temperature, faster cycle, less drying requirement). A PP part typically costs 30-40% less to mold than an equivalent nylon part. This cost advantage drives PP’s dominance in packaging and consumer disposables.
Can nylon and PP be glued or welded together?
No — nylon and PP are chemically incompatible and cannot be welded or adhesively bonded together. Choose one material or use mechanical fasteners (screws, snap fits) to join parts made from different materials.
Not sure which material fits your application?
Send us your requirements and we’ll recommend the right engineering plastic — nylon, PP, acetal, or something more specialized.
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