The light stabilizer is an additive of a polymer product (for example, plastic, rubber, paint, synthetic fiber), a plastic additive capable of suppressing or reducing the degradation of light to plastic, and improving the light resistance of the plastic material.
Most of them absorb ultraviolet light, so they are also called ultraviolet absorbers. Ultraviolet rays in sunlight are the main cause of aging effects on polymer materials. Although ultraviolet light is about 5% of sunlight, its energy is very large. Its energy is enough to destroy the chemical bond of the polymer, causing its molecular chain to break and crosslink, causing its mechanical properties to become malignant, and its color also changes.
According to the action mechanism, it can be divided into 1) light shielding agent, 2) ultraviolet absorber, 3) quencher, and 4) radical trapping agent.
1) Light-shielding agent: It acts like a barrier between the polymer and the light radiation, so that the light cannot be directly radiated into the interior of the polymer, so that the inside of the polymer is not harmed by ultraviolet rays, thereby effectively suppressing photo-oxidation. degradation.
2) Ultraviolet absorber: Its mechanism of action is that it can strongly absorb the sensitive ultraviolet light of the polymer and can convert the energy into harmless heat energy.
3) Quencher: It can accept the energy absorbed by the chromophore in the plastic and disperse it in the form of heat, fluorescence or phosphorescence, and return it to the base to protect the polymer from UV rays.
4) Radical Scavenger: This kind of light stabilizer can capture the active radicals generated in the polymer, thereby inhibiting the photooxidation process and achieving light stabilization.
Plastic light stabilizers have long been used not only in the rubber, paint, and chemical fiber industries, but also in the plastics industry for 40 to 50 years, especially for ABS resins and polyoxymethylene. Others such as polyamides, polycarbonates, acrylate resins, cellulose resins and the like may also be used as light stabilizers. The use of plastic auxiliaries light stabilizers not only protects the materials themselves, but also has good protective effects on packaged materials that are susceptible to ultraviolet light, such as drugs and foods. Therefore, light stabilizers will have broad development prospects in the plastics industry.
National Hose thread (NH) couplings, also known as National Standard Thread (NST). It is the most common type of fire hose coupling used in the United States. The male and female straight (non-tapered) threads screw together and the connection is sealed with a gasket.
NH Coupling include brass and aluminum NH couplings
NH couplings were used widely in Canada, USA and South American zone.
Main sizes include 1.5``,2`` and 2.5``.
NH Coupling
NH Coupling,NH Standard Coupling,NH Hose Coupling,NH Fire Hose Coupling
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