PA66 GF Rod PA66 Glass Fiber Black Bar
Basic properties of nylon 66 and glass fiber reinforcement
Essential properties of nylon 66 (PA66) (basic properties when not reinforced)
Nylon 66 is a linear thermoplastic polymer synthesized by polycondensation of adipic acid and hexamethylenediamine. The molecular chain contains a large number of amide groups (—CONH—), which give it the following core properties:
Excellent mechanical properties
The tensile strength of unreinforced PA66 is about 60-80 MPa, the flexural strength is about 90-110 MPa, and the impact strength (simple supported beam unnotched) is about 5-10 kJ/m². It has high hardness and rigidity (Rockwell hardness R110-120), and is suitable for structural parts that bear medium loads.
Good wear resistance and self-lubrication
The friction coefficient is low (about 0.15-0.3 when rubbing against steel) and it has self-lubrication (no additional lubricating oil is required). It is particularly suitable for sliding bearings, gears and other parts that require low friction (such as parts around automobile engines).
Outstanding chemical resistance
It is stable to most non-oxidizing acids (such as dilute sulfuric acid, hydrochloric acid), alkalis (such as dilute sodium hydroxide), salt solutions and organic solvents (such as gasoline, lubricating oil), but will degrade in strong oxidizing acids (such as concentrated nitric acid, concentrated sulfuric acid).
Significant water absorption and dimensional instability
The equilibrium water absorption rate of unreinforced PA66 is as high as 2.5% - 3.5% (rapid water absorption in a humid environment). After absorbing water, the dimensions expand (the linear expansion coefficient increases by 30% - 50%), the tensile strength decreases (the decrease is about 30%), and the rigidity and electrical insulation deteriorate (the volume resistivity decreases from 10¹⁵ Ω·cm to 10¹² Ω·cm), causing the parts to easily deform and fail in a humid environment.
The heat deformation temperature (HDT, under a load of 1.82 MPa) is only 50-70℃ (short-term resistance 80-90℃), and the long-term use temperature is ≤80℃, which limits its application in high-temperature scenarios.
The Core Value of Glass Fiber Reinforcement (GF)
Glass fiber (GF) is an inorganic fiber (diameter 5-20 μm, commonly used length 3-12 mm) made by high-temperature melt drawing of quartz sand (SiO₂). It exhibits extremely high tensile strength (≥2000 MPa), elastic modulus (≥70 GPa), and heat resistance (long-term operating temperature ≥400°C). When GF is added to the PA66 matrix at a ratio of 10% to 60% (mass fraction), a composite structure of "matrix load + fiber reinforcement" is formed through physical entanglement and interface bonding (coupling agent such as KH550 needs to be added to improve the affinity between GF and PA66), giving the PA66 GF rod the following core modification effects:
Significantly improve rigidity, strength and dimensional stability
Tensile strength: From 60-80 MPa of pure PA66 to 120-200 MPa (20% GF) or 180-250 MPa (40% GF), close to 50%-60% of low carbon steel (Q235 has a tensile strength of about 400 MPa), and can replace some metal structural parts.
Flexural strength: Increased from 90-110 MPa to 180-300 MPa (40% GF), flexural modulus (a measure of stiffness) increased from 2-3 GPa to 8-12 GPa (pure PA66 is only 2-3 GPa), making parts less susceptible to bending and deformation.
Dimensional stability: Water absorption reduced from 2.5%-3.5% to 0.5%-1.5% (40% GF), and the linear thermal expansion coefficient decreased from 8×10⁻⁵/°C (pure PA66) to 2-3×10⁻⁵/°C (close to 1.5×10⁻⁵/°C) of aluminum alloy. Dimensions remain virtually unchanged in humid or temperature-stable environments (suitable for precision mechanical components).
Significantly improve heat resistance
The addition of glass fiber limits the movement of PA66 molecular chains, and the heat deformation temperature (HDT) is increased from 50-70℃ (pure PA66) to 200-240℃ (40% GF, 1.82 MPa load). The long-term use temperature can reach 120-150℃ (short-term resistance 180-200℃), meeting the requirements of high-temperature working conditions (such as engine peripherals and oven parts).
Enhanced fatigue resistance and creep resistance
Under cyclic loads (such as repeated bending and vibration), the fatigue life of PA66 GF rods is 3-5 times longer than that of pure PA66 (suitable for bearings and gears in long-term operation); under constant stress (such as bolt preload), the creep resistance is significantly improved (the deformation amount after 24 hours at 100℃ is ≤0.1%, while pure PA66 may exceed 1%).
Retaining some wear resistance and self-lubricating properties
Although the addition of glass fiber will slightly reduce the friction coefficient of PA66 (from 0.15-0.3 to 0.2-0.4), it is still lower than that of metal (the friction coefficient of steel is about 0.5-0.7), and its wear resistance is better than most metals (the wear rate is more than 50% lower than that of steel), making it suitable for low-speed sliding scenarios (such as guide rails and bushings).
