Main Traits with High Density Polyethylene2
HDPE is a kind of thermoplastic resin with high crystallinity and non-polarity. Original HDPE appears milk white and semi translucent in a tiny section to some degree. PE has great resistance to most chemicals in life and business. Some sorts of chemicals will produce chemical erosion, like corrosive antioxidant (nitric acid), aromatic hydrocarbons (dimethyl benzene) and halogenating hydrocarbon (carbon tetrachloride). The polymer doesn’t absorb moisture and has very good steam resistance, which may be utilized for packaging. With fairly good electricity performance, specially the strength of insulation and dielectric, HDPE is particularly applicable to make wire and cable. What’s more, HDPE with medium to high molecular level possesses particularly very good impact resistance, even in low room temperature of 40 F.
Unique characteristic of a variety of levels of HDPE is the proper mixture of the following 4 basic variables: density, molecular weight, distribution of molecular weight and additives. Distinct sorts of additives are employed within the production of polymers with special performance. Hence, these variables combine to generate HDPE with different levels and usages; the performance is usually within the best balance.
Density is the main variable that decides the characteristics of HDPE, though four variables mentioned play a role that influence one another. Ethylene is the primary raw material of polyethylene. Couple of other monomers, like l-fullerene and 1-essien, are also frequently utilised to enhance the performance of polymer. For HDPE, the content of couple of monomers above is generally less than 1% to 2%. An added monomer fairly reduces the crystallinity of polymer. This alter is commonly measured by density, though density and crystallization rate are in a linear rapport. In line with regulations of ASTM D1248, the United States typically classified HDPE. HDPE density is 0.940g /CC or above; medium density of polyethylene (MDPE) is 0.926 ~ 0.940 g/CC. In other classification, sometimes MDPE is classified as ptfe rod or LLDPE.
Homo-polymer with the very best density and the biggest stiffness has very good permeability control and the greatest melting point. But typically it has fairly poor cracking resistance to environmental anxiety (ESCR). At the identical time, ESCR is resistance of PE to cracking caused by mechanical or chemical anxiety. Greater density more often than not improves the mechanical strength performance, which include tensile strength, stiffness and hardness. The main raw materials used to make teflon film. Thermal properties which include softening point temperature and heat distortion temperature are enhanced; the permeability, for instance gas permeability and water vapor permeability are also promoted. Meanwhile, the lower density improves the impact strength and E-SCR.