Not all plastic fasteners are the same. Choosing the right material grade is essential for your project’s success.
This guide compares the most popular engineering plastics used in manufacturing.
Nylon 66 (PA66) and Reinforced Grades
Nylon 66 is the most common choice. It is strong, tough, and affordable. It works well for general industrial use.
If you need more strength, choose Glass-Filled Nylon. Adding glass fibers increases stiffness and reduces thermal expansion. It makes the plastic feel almost like metal.
| Property | Standard Nylon 66 | 30% Glass-Filled (GF30) | 50% Glass-Filled (GF50) |
| Tensile Strength | Good (Standard) | High (2x Standard) | Very High (3x Standard) |
| Stiffness (Modulus) | Flexible / Tough | Rigid | Extremely Rigid |
| Heat Resistance | Up to 80-100°C | Up to 120-150°C | Up to 160°C+ |
| Weight | Lowest (1.14 g/cm3) | Medium (1.35 g/cm3) | Higher (1.55 g/cm3) |
| Dimensional Stability | Moderate | High (Resists warping) | Best (Metal-like) |
| Best For: | Spacers, Washers, Clips | Automotive, Brackets | Structural Housings |
Polypropylene (PP)
PP is a lightweight and flexible material. Its biggest advantage is chemical resistance. It stays stable in many acids and bases. However, it is not as strong as Nylon. Use PP for low-load applications in chemical laboratories or water treatment systems.
The “Lighter Than Water” Advantage (Ultra-Lightweight)
PP is one of the few solid materials with a density below 1.00 g/cm3 (typically 0.90 – 0.91).
Impact on Design: For drones, portable medical devices, and aerospace sensors, every gram counts. Switching from Nylon (1.14 g/cm3) to PP reduces the fastener weight by another 20%. Compared to steel, it is nearly 9 times lighter.
The Reality: If you drop a PP bolt into a glass of water, it will float.
“Living Hinge” Flexibility (Superb Pliability)
Unlike Nylon, which is rigid and can be brittle when dry, PP is naturally pliant and flexible.
The Living Hinge: This material is famous for its “fatigue resistance.” You can bend a PP component thousands of times, and it will not create a stress crack. This makes PP clips and snap-fit fasteners far more durable in applications that require frequent opening or moving parts.
Anti-Cracking: PP fasteners can absorb heavy impacts without snapping. They “give” under pressure and return to their original shape.
PVDF (Polyvinylidene Fluoride)
PVDF is a high-end “super plastic.” It is incredibly resistant to UV light and harsh weather. It also handles very strong chemicals. If your project is outdoors or involves high-purity fluids, PVDF is the best choice. It is more expensive but lasts a very long time.
The Power of the Fluorine-Carbon Bond
The secret to PVDF’s invincibility lies in its atomic structure. It is composed of strong Fluorine-Carbon (F-C) bonds.
The “Chemical Armor”: The F-C bond is one of the strongest in organic chemistry. It requires immense energy to break.
UV Resistance: Standard plastics (like PE or some PVC) have bonds that are easily broken by the energy in UV radiation, leading to “chalking” or brittleness. PVDF’s bonds are so stable that UV rays simply bounce off or pass through without causing chemical damage. Even after 20+ years of direct tropical sun exposure, PVDF fasteners show almost zero degradation.
Extreme Weather & Thermal Stability
PVDF doesn’t just survive the sun; it survives the cycle of seasons.
Low Thermal Expansion: Unlike many plastics that expand and contract significantly with temperature changes (causing bolts to loosen), PVDF is remarkably stable.
Working Range: It maintains its mechanical strength from -50°C to 150°C. Whether in an arctic winter or a scorching desert, PVDF fasteners remain functional.
Total Chemical & Ozone Resistance
“Harsh weather” often includes acid rain, salt spray, or high ozone levels in industrial cities.
Hydrophobic Surface: It naturally repels water. This prevents “moisture-induced swelling” and ensures that ice doesn’t bond strongly to the fastener surface in freezing conditions.
Zero Corrosion: PVDF is virtually inert to most acids, salts, and oxidants.
PPS (Polyphenylene Sulfide)
PPS is designed for high-temperature environments. While most plastics soften in heat, PPS remains rigid. It is also very stable in terms of size. This makes it perfect for engine components or industrial ovens where precision is required.
Continuous Service Temperature
PPS has a very high melting point (about 280 ° C).
Long-term Stability: Unlike Nylon, which may degrade or oxidize over time when exposed to heat, PPS can operate continuously at 200∘C to 240∘C without losing its mechanical properties.
Heat Deflection: Its Heat Deflection Temperature (HDT) is typically around 260∘C.
Exceptional Dimensional Stability
Heat often causes materials to expand. In precision engineering, even a 0.1 mm change can lead to mechanical failure.
Low Creep: PPS has very low “creep” (deformation under constant load). Even in a hot engine bay, a PPS bolt will not stretch or loosen.
Low Expansion: It has a very low coefficient of thermal expansion, ensuring that your fastened parts stay perfectly aligned regardless of temperature swings.
Inherent Flame Retardancy
Unlike many plastics that require chemical additives to stop burning, PPS is naturally flame-retardant.
Low Smoke: In the event of extreme heat, it produces very little smoke, making it safer for aerospace and public transport applications.
Safety Rating: It typically meets the UL94 V-0 standard without any additives.
How to Choose Plastic Fasteners?
Below is the chart comparing related properties by these common type of plastic fasteners:
| Material | Density (g/cm3) | Tensile Strength (MPa) | Service Temp (∘C) | Corrosion Resistance | Key Features | Primary Applications |
| Nylon 66 (PA66) | 1.14 | 70 – 85 | -40 to 100 | Moderate (Oil/Fuel) | Tough, Affordable | General Industrial, Spacers |
| PA66 + 30% GF | 1.35 | 150 – 180 | -40 to 120 | Moderate | High Stiffness, Rigid | Automotive, Brackets |
| Polypropylene (PP) | 0.91 | 30 – 40 | 0 to 100 | High (Acids/Bases) | Ultra-light, Floats | Chemical Tanks, Batteries |
| PVDF | 1.78 | 50 – 60 | -50 to 150 | Near-Universal | UV & Weather Proof | Solar, Marine, Semi-con |
| PPS | 1.65 | 160 – 200 | -40 to 240 | Excellent (High) | Extreme Heat, Stable | EV Engines, Industrial Ovens |
- For General Use: Stick with Nylon 66.
- For High Heat: Choose PPS.
- For Chemicals: Go with PP or PVDF.
- For Strength: Use Glass-Reinforced Nylon.
Selecting the right grade ensures your product performs safely for years.