November 6, 2023
1. PA (nylon): 8026 upper cover, 532 support body, 049D inner core, etc
① The original color is milky white, slightly brown, burns slowly, and extinguishes slowly after leaving the fire. The flame is yellow at the top and blue at the bottom. It melts, drips, and bubbles, and has a special smell of burnt sheepskin or nails.
② Better physical and mechanical properties.
③ Stress test: n-propane, no cracks or cracks.
2. ABS: terpolymer of three monomers: acrylonitrile, butethylene and styrene
① The original color is milky white or white, opaque, burns slowly, and continues to burn after being removed from the fire. The flame is yellow and black smoke, softened and charred, and soluble in acetone, benzene, and toluene.
② Acrylonitrile has tensile strength, thermal stability, and chemical stability, butadiene has toughness, impact resistance, and low-temperature performance, and styrene has good gloss, rigidity, and processability, adjusting the ratio between the three can adjust high-impact, medium-impact, general-purpose, and special heat-resistant ABS. Disadvantages: heat resistance is not high enough, easy to age, not flame-resistant and opaque.
③ Stress test: soaked in more than 95% acetic acid for 30 seconds, no deformation, cracks or breaks.
Carbon tetrachloride and alcohol are mixed into a solution of 1:1 or 4:6, soak PC products, and observe the time and size of cracks. This is a commonly used method at present.
4. PE: polyethylene
① The original color is translucent - waxy, flammable, yellow at the top and blue at the bottom, dripping while melting, with the smell of paraffin, insoluble in solvents at room temperature, soluble in acetone, benzene and formaldehyde when heated.
② According to the processing method, it can be divided into high-density PE and low-density PE. High-density PE is a translucent waxy solid with tough texture, impermeability, wear resistance, and good chemical resistance. Disadvantages: size reduction due to stress disappearance after heating, poor flexibility and resistance to severe cold and heat. Low-density PE is a colorless, odorless and non-toxic solid. It can maintain flexible properties at low temperatures, is water-resistant and has strong chemical stability.
③ Stress test: sodium stearate or soapy water, no deformation, cracks or breaks.
5. PMMA: organic glass, acrylic
① The original color is colorless, transparent, and flammable. It continues to burn after being removed from the fire. The top of the flame is yellow and the bottom is light blue. It melts and drips. It can be bent freely when heated to 120°C. It does not become turbid and emits a unique acrylic smell. It is easy to Melts in acetone and benzene.
② High transparency, high light resistance, refractive index, self-bonding with acetone, chloroform and other solvents, product molding shrinkage 0.1-0.8%, hygroscopicity of the material pellets can cause foaming of the product.
③ Stress test: ethanol or isopropyl alcohol, no cracks or cracks for ten seconds.
6. POM: polyoxymethylene
① The original color is light yellow or white, burns slowly, and continues to burn after being removed from the fire. The upper part of the flame is yellow and the lower part is blue, melting and dripping, and has a strong fishy smell.
② Strong mechanical properties, shortcomings are not resistant to acid, strong alkali and sunlight and ultraviolet radiation. It will age if exposed to the atmosphere for a long time and has poor adhesion.
③ Stress test: soaked in 12-18% hydrochloric acid solution for 2 hours, no deformation or cracks.