Cosmetics hoses structure and properties of polyethylene tube in polyethylene is a high molecular compound composed of ethylene polymerization. Polyethylene as the molecular weight of the plastic in plastic packing tube more than 10000. According to the different polymerization conditions, from millions of high molecular weight polyethylene molecular weight can be polyene.
Cosmetics hoses according to different molecular weight and density, the polyethylene is divided into low molecular weight polyethylene (vlmpe), linear low density polyethylene (LLDPE), low density polyethylene, medium density polyethylene (MDPE) and high molecular weight polyethylene), etc. Density: the density of HDPE is 0941 ~ 0967 g/CH, and uhmwpd095 ~ 0.97 g/cm crystallinity, the crystallinity of the LDPE is about 65%, HDPE is about 80 ~ 90%. 1.1 mechanical properties of crystallinity and molecular weight determines its mechanical properties.
In general, LDPE has flexibility and impact resistance, tensile strength, stiffness and hardness of the HDPE were better than LDPE, is advantageous to the product of the thin wall and lightweight. The molecular structure of the LLDPE between linear HDPE and long branches of LDPE, so its physical and mechanical properties between LDPE and HDPE. 1.2 thermal properties of HDPE melting point is 135 ℃, LDPE continuous use under 60 ℃ temperature, continuous use of HDPE temperature below 80 ℃.
1.3 chemical permeability is the permeability plastic packaging tube of HDPE is far lower than the LDPE. Compared with other plastics, etc. With high permeability, but the lower the permeability of water vapor. Chemical resistance of polyethylene is a nonpolar crystalline polymer, thus it has excellent chemical stability. Cosmetics hose acid and salt water solution under normal temperature, even in relatively high concentrations is no obvious effect on polyethylene. But the sulfuric acid, nitric acid such as antioxidant will slowly corrosion polyethylene.
Polyethylene in aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbon swelling, but most tolerated under 60 ℃ solvents. Polyethylene solubility in organic solvent and swelling degree increased with the increase of molecular weight and crystallinity decreased, so than HDPE LDPE has better chemical stability products mechanical performance and electric performance decline, gradually become fragile, loss of performance. Cosmetics hoses to prevent PE degradation, need to add antioxidant and light stabilizer in polyethylene.
Poly (7 - ene) is a kind of no polar group in eye cream packing tube the molecular structure of nonpolar polymer hydrocarbon, so it has excellent electric properties. Affected by the frequency is small. Polyethylene is easy molding, without adding plasticizer processing, simple operation, easy to mass production. Cosmetics hoses are commonly used processing method of extrusion, injection, blow molding, foaming, thermoforming, general processing molding should pay attention to the following: polyethylene heat capacity is big, but the processing temperature is low.
Processing temperature mainly depends on the density and crystallinity. Therefore, we should try to reduce the melt contact with air and the residence time under high temperature. Cosmetics, the crystallinity of hose products depends on the cooling rate control in molding. Either fast or slow cold, product cooling speed of each part should be as evenly as possible, lest produce internal stress, reduce the mechanical properties of the products.
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