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Namangan muhandislik-texnologiya instituti
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| bet | 4/4 | | Sana | 21.02.2024 | | Hajmi | 0,56 Mb. | | #159949 |
Bog'liq Oybek Low density polyethylene
Low density polyethylene (LDPE) is a high branched PE. Its high ramification confers a low density to the molecule as well as a lower hardness, stiffness and strength than high density polyethylene, but with higher ductility. It is semitransparent, and only thin foils can be transparent. That strong ramification hinders the packing of the molecules, diminishing the crystallinity of the material.
LDPE is widely used in packaging like foils, trays and plastic bags for both food and nonfood purposes. It is also used as protective film on paper, textiles and other plastics. For instance, one of the most famous applications is in milk cartons, where it forms part of a system of different plastic layers. Other applications are wrapping foil for packaging, plastic bags (the soft type that does not crackle), garbage bags, tubes or ice cube plastic bags.
LDPE Homopolymer
Low density polyethylene polymers are called homopolymers because they are produced with only one monomer (ethylene). The branching controls the polymer density. The free radical process allows both LCB and SCB to be incorporated into the polymer molecule (Fig. 2-16). The SCB creates a defect when the polymer molecule crystallizes, forcing smaller lamella to form (which lowers density).
Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching. The linearity of LLDPE results from the different manufacturing processes of LLDPE and LDPE. In general, LLDPE is produced at lower temperatures and pressures by copolymerization of ethylene and such higher alpha-olefins as butene, hexene, or octene. The copolymerization process produces an LLDPE polymer that has a narrower molecular weight distribution than conventional LDPE and in combination with the linear structure, significantly different rheological properties.
A polyolefin is a type of polymer produced from a simple olefin as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin ethylene. Polypropylene is another common polyolefin which is made from the olefin propylene.
1-Octene is an organic compound with a formula CH2CHC6H13. The alkene is classified as a higher olefin and alpha-olefin, meaning that the double bond is located at the alpha (primary) position, endowing this compound with higher reactivity and thus useful chemical properties. 1-Octene is one of the important linear alpha olefins in industry. It is a colourless liquid.
Plastic milk containers are plastic containers for storing, shipping and dispensing milk. Plastic bottles, sometimes called jugs, have largely replaced glass bottles for home consumption
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