Chemical modification of polyethylene
DATE：2021/4/9 8:34:13 / READ： / SOURCE：This station
Chemical modification of polyethylene
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(1) Properties of metallocene polyolefin elastomer
Metallocene polyolefin elastomer (POE) is an ethylene / octene copolymer developed by Dow Chemical Company in 1994 by using the limited geometry catalyst technology (CGCT) (also known as in site technology). As an elastomer, the mass fraction of octene monomer in Poe is usually more than 20%. At present, the product is produced and operated by Du Pont Dow elastomers with a production capacity of 180000 tons. Poe is produced by solution polymerization process. The polymerization temperature is 80 ~ 150 ° C and the polymerization pressure is 1.0 ~ 4.9 MPa. The crystalline region (resin phase) of polyethylene acts as a physical crosslinking point. The introduction of - Quantitative octene weakens the crystalline region of polyethylene and forms an amorphous region (rubber phase) with rubber elasticity. Compared with the polymer prepared by traditional polymerization method, it has very narrow molecular weight distribution and short branched chain distribution, so it has excellent physical and mechanical properties such as high springing, high strength, high elongation and good low temperature properties. Because its molecular chain is saturated and contains relatively few tertiary carbon atoms, it has excellent heat aging resistance and ultraviolet resistance. The narrow molecular weight distribution makes the material not easy to bend in the process of injection and extrusion. On the other hand, CGCT technology can also introduce long branched chains into the linear short chain branched structure of polymer, thus improving the processing rheological properties of polymer and increasing the transparency of material. A series of Poe materials with different density, Mooney viscosity, melt flow rate, tensile strength and hardness can be synthesized by precise design and control of polymer molecular structure. Air permeable film production line www.handern.com
(2) Application
① Impact modifier of PP: Poe as impact modifier of PP has obvious advantages over traditional EPDM. Firstly, the granular Poe is easy to mix with the granular PP, which saves the complex granulation or premixing process of block ethylene propylene rubber; secondly, Poe and PP have better mixing and dispersion effect, and the phase of the copolymer is finer than EPDM, which improves the impact resistance; Finally, general rubber was used as the impact modifier of PP to improve the impact strength and reduce the yield strength of the product, while Poe elastomer kept higher yield strength and good processing fluidity at the same time of toughening. ② Thermoplastic elastomer material: due to the high strength and elongation of Poe, and good aging resistance, Poe can be directly processed into products for some products with low requirements for heat resistance grade and loose requirements for permanent deformation, greatly improving the production efficiency, and the material can be reused. Air permeable film production line www.handern.com
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