Principal Properties with High Density Polyethylene
HDPE is a kind of thermoplastic resin with high crystallinity and non-polarity. Original HDPE appears milk white and semi translucent in a modest section to some degree. PE has outstanding resistance to most chemicals in life and industry. Some styles 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 excellent steam resistance, which may be used for packaging. With extremely very good electricity performance, in particular the strength of insulation and dielectric, HDPE is quite applicable to make wire and cable. What’s more, HDPE with medium to high molecular level possesses particularly beneficial impact resistance, even in low room temperature of 40 F.
Unique characteristic of many levels of HDPE may be the appropriate combination of the following 4 fundamental variables: density, molecular weight, distribution of molecular weight and additives. Diverse types of additives are employed within the production of polymers with special performance. Thus, these variables combine to generate HDPE with different levels and usages; the performance can be in the most effective balance.
Density is the main variable that decides the characteristics of HDPE, even though four variables mentioned play a role that influence one another. Ethylene is the primary raw material of polyethylene. Couple of other monomers, which include l-fullerene and 1-essien, are also frequently used to increase the performance of polymer. As to HDPE, the content of couple of monomers above is frequently much less than 1% to 2%. An added monomer a little bit reduces the crystallinity of polymer. This change is more often than not measured by density, while density and crystallization rate are in a linear connection. According to regulations of ASTM D1248, the United States usually 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, occasionally MDPE is classified as ptfe rod or LLDPE.
Homo-polymer with the greatest density and also the biggest stiffness has good permeability control and the highest melting point. But more often than not it has exceptionally poor cracking resistance to environmental anxiety (ESCR). At the exact same time, ESCR is resistance of PE to cracking caused by mechanical or chemical stress. Higher density in most cases improves the mechanical strength performance, including tensile strength, stiffness and hardness. The main raw materials used to make teflon film. Thermal properties like softening point temperature and heat distortion temperature are enhanced; the permeability, including gas permeability and water vapor permeability are also promoted. Meanwhile, the lower density improves the impact strength and E-SCR.