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LDPE Low density polyethylene
LDPE Low density polyethylene: is the most common type of PE. LDPE resins are synthesized in such a way that a highly branched polymer is formed. It consists of a short chain branch (less than six carbon atoms) and a long chain branch (approximately the length of the main circuit). Interrupt the sequence of the polymer and prevent local crystallization. Less crystallization at lower densities.
LDPE resins are synthesized by free radical method at high pressure. (see more: LDPE Agriculture Film )
There are two main types of reactors: autoclave reactors or tubular reactors. Autoclave reactors tend to provide multiple branches that increase dispersion, LDPE has a wide melting range, with the highest melting point at 110 ° C, LDPE density usually ranges from 0.91 ÷ 0.93 g / cm3, LDPE has rheological properties so it is suitable for film production by film blowing method, so it is relatively easy to handle. ( see more: LDPE Film grade )
Compared to other types of PE, it melts at relatively low temperatures (220 ÷ 240 ° F, 105 ÷ 115 ° C). The yield strength, low shear viscosity and thin slip properties of LDPE increase the processing capability without consuming much energy for the extruder. ( see more: LDPE Film Grade Mix Color )
The LDPE type used for blowing films has moderate viscosity, but many branches require a relatively wide processing door and high thermal stability in bubbles. This results in a stable bubble that can work with low LDPE cooling line heights that are easily soldered, soft, tough and the cheapest.
Applications in packaging
Different types of LDPE with different slip coefficients will have different applications in packaging. For products that need to pack large quantities of products, they need low slip coefficient to have good dynamic loading.( see more: LDPE Injection Regrind )
Packing soft products in bag packaging requires a high slip coefficient. LDPE is most often used to make thin films for making bags.