At present, plastic waterproof junction box materials are mainly ABS and polycarbonate engineering plastics. The following is a brief introduction to the properties of the two resins:
One, ABS.
ABS resin for acrylonitrile (23%-41%), butadiene (10-30%) and stupid ethylene (29%-60%) three monomer copolymerization of amorphous polymer, referred to as ABS. Its performance is as follows:
(1) ABS is non-toxic and tasteless, and its appearance is ivory translucent, or transparent granule or powder. The density is 1.08-1.18/cm3, the search rate is 0.4%-0.9%, the hygroscopicity is less than 1%, the melting temperature is 217-237℃, the thermal decomposition temperature is greater than 250℃.
(2) ABS is hard and tough, rigid, low temperature impact resistance, creep, dimensional stability, wear resistance are good; Linear expansion coefficient is very small, forming shrinkage, excellent surface gloss.
(3) ABS electrical insulation performance is good, and almost not affected by temperature, humidity and frequency, can be used in most environments.
(4.). The thermal deformation temperature of ABS is 93-118℃, and the product can be increased by about 10℃ after annealing treatment. It can be used in the temperature range of -40℃-100℃, and can still show a certain toughness at -40℃.
(5) ABS is flammable, the flame is yellow, black smoke, has a special odor, but does not drip.
(6).ABS is not subject to water. Inorganic salts, alkali and a variety of acids, but soluble in ketones, aldehydes and chlorinated hydrocarbons, glacial acetic acid, vegetable oil erosion will produce stress cracking; ABS has poor weather resistance and is easy to degrade under the action of ultraviolet light. After half a year outdoors, the impact strength will be greatly reduced.
(7).ABS has strong adsorption, is an excellent material for plastic electroplating, good compatibility with polar resin, can change the performance of PVC.
Two, polycarbonate (PC)
Polycarbonate is a kind of linear polymer in which the carbonate groups in the macromolecular chain are arranged alternately.
(1) PC is transparent or white hard and tough thermoplastic resin, good flame retardant, flame is yellow when burning, melting bubbles, flowers and fruit smell, from the fire extinguish.
(2) PC is a high transparent resin, light transmittance is 85%-90%, refractive index 1.589, close to PMMA(plexiglass), suitable for lens materials.
(3) PC has strong and tough mechanical properties, and its impact resistance is excellent among thermoplastic materials, more than 3 times higher than PA and POM, close to the level of PF and UP glass fiber reinforced plastics; It has good tensile strength, bending strength and dimensional stability, poor stress cracking resistance and high notch sensitivity.
(4) EXCELLENT thermal performance of PC, the product can be used in the temperature range of -60-125℃; The thermal deformation temperature is about 130-140℃, embrittlement temperature is about -100℃, and melting point is about 220-230℃. Good electrical insulation performance; The volume resistance is 5×1016 ω.cm, which is worse than PE, PS and PTFE. The thermal conductivity and linear expansion coefficient are small.
(5) PC chemical resistance is stable, at room temperature resistance to dilute acid, water, oil, aliphatic hydrocarbons, salts and oxidants; Not resistant to hot water above 60 degrees c; PC is soluble in dichloromethane, chlorobenzene, dioxane.
