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Short introduction of the LDPEPolyethylene (PE) resins are a general class of thermoplastics produced from ethylene gas. Ethylene gas is derived from the cracking of natural gas feedstocks or petroleum by- products. Under broad ranges of pressures,temperatures and catalysts (depending PE type), ethylene generally polymerizes to form very long polymer chains. Polyethylene products are typically classified by their melt index and density. The melt index provides a general indication of a product’s molecular weight (MW) and processability. A higher melt index resin will typically have a lower molecular weight and process (flow) easier; however, it usually has decreased physical properties as a result of the lower MW. Density measures crystallinity. As density and crystallinity increase, stiffness increases and impact decreases. Low density polyethylene (LDPE) is produced by autoclave or tubular reactor technology. Each reactor type operates at high pressures(up to 45,000 psig). The resulting polymer is highly branched, which results in its low density and unique physical properties. Vinyl acetate (VA) can be added to produce copolymer products that can have increased clarity (at low VA levels) and increased flexibility. The high level of long-chain branching (LCB), as shown in Figure 1, of LDPE causes the polymer to have low crystallinity and low density ranging from 0.915 to 0.935 g/cc. As a result of the low crystallinity of LDPE, the end- use applications are flexible and soft. Just because LDPE material is flexible and soft ,it's used to produce the ziplock bag ,outer packaging bag ,shopping bag ,handle bag ,Garbage bag and so on.please see the following pictures,they are produced by LDPE material. | ADD Time:2013.05.23 Form: Click:5430 |
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