Resin polyethylene

Polyethylene. Polyethylene remains the largest volume film and sheet raw material. It is available in a wide range of types, with variations in copolymers, homopolymers, molecular weight, and other factors contributing to a long Hst of resins. Resins are designed specifically for end use, and in addition blends of the various types may be used by processors to optimize properties, processibiUty, and economics. Almost two-thirds of the volume of all polyethylene resins are used in film or sheet appHcations (see Olefin polymers). 

Fig. 1. Stress—strain curves for ionomer and polyethylene resins. Test speed is 5 cm/min. The reference matedal is high molecular weight conventional...

Polyethylene. Traditional melt spun methods have not utilized polyethylene as the base polymer because the physical properties obtained have been lower compared to those obtained with polypropylene. Advances in polyethylene technology may result in the commercialization of new spunbonded stmctures having characteristics not attainable with polypropylene. Although fiber-grade polyethylene resin was announced in late 1986 (11,12), it has seen limited acceptance because of higher costs and continuing improvements in polypropylene resin technology (see Olefin POLYMERS, POLYETHYLENE). 

Selection of a polyethylene resin with no additives or with FDA qualified additives usually insures good direct mutual chemistry between the plastic and the food product, and many food products can be shipped... 

Antioxidant additive in the polyethylene resin. While such an additive can prevent oxidation, and thus odor, it also can contribute directly to the odor. If an antioxidant is needed, it must be FRA approved, should have a high melting point, and should be used at a minimum level consistent with the extrusion process. Catalyst residues and antioxidants present in polyethylene sometimes interact to form odorous products. 

Low molecular weight fractions can be detected by smelling the inside of almost any freshly made polyethylene container. The amount varies with the specific polyethylene resin and the type of processing that have been used. 

In order to determine the branching structure factor e, Foster ( ) studied a large qroup of high pressure low density polyethylene resins (HP-LDPE). Using the MWBD method, he calculated the whole polymer number average number of branch points per JOOO carbon atoms from SEC data as a function of e. Then the Xfj values were compared with those obtained by nMR. 

The mechanisms described above tell us how heat travels in systems, but we are also interested in its rate of transfer. The most common way to describe the heat transfer rate is through the use of thermal conductivity coefficients, which define how quickly heat will travel per unit length (or area for convection processes). Every material has a characteristic thermal conductivity coefficient. Metals have high thermal conductivities, while polymers generally exhibit low thermal conductivities. One interesting application of thermal conductivity is the utilization of calcium carbonate in blown film processing. Calcium carbonate is added to a polyethylene resin to increase the heat transfer rate from the melt to the air surrounding the bubble. Without the calcium carbonate, the resin cools much more slowly and production rates are decreased. 

We make polyethylene resins using two basic types of chain growth reaction free radical polymerization and coordination catalysis. We use free radical polymerization to make low density polyethylene, ethylene-vinyl ester copolymers, and the ethylene-acrylic acid copolymer precursors for ethylene ionomers. We employ coordination catalysts to make high density polyethylene, linear low density polyethylene, and very low density polyethylene. 

The physical characteristics of polyethylene resins vary widely as a function of their density. The density of polyethylene is highest when it has very few branches to impede the crystallization process. A 3 mm thick plaque of high density polyethylene is an opaque white solid that can... 

Polyethylene polymers history of, 17 701-702 simulations of, 16 747 Polyethylene products, Ziegler-Natta catalysts for, 26 540-543 Polyethylene resins, 17 700-703 applications for, 17 703 Polyethylenes, classification of, 17 701t. 

The effect of the components and conditions of preparation on the properties of a 70/30 LDPE/clay composite is shown in Table I. The 10/90 mixture of LDEE Bakelite Polyethylene Resin DYNH-1 (Union Carbide Corp.) and Hydrite 10 clay (Georgia Kaolin Co.) was compounded at 150 C in the Brabender Plasticorder in the presence of MAH and/or t-butyl perbenzoate (tBPB). The EE-coated clay was then mixed with additional DYNH-1 LDPE at 130°C to yield a 70/30 PE/clay composite. A 30 70 PE/clay concentrate was prepared in a similar manner at 150 C and converted to a 70/30 EE/ clay composite at 130 C. The 10/90 PE/clay concentrate is an easily handled, clay-like product while the 30/70 concentrate is... 

Spalding, M.A. and Hyun, K.S., Coefficients of Dynamic Friction as a Function of Temperature, Pressure, and Velocity for Several Polyethylene Resins, Polym. Eng. Set, 35, 557 (1995)... 

Electron beam irradiation is one of the methods of cross-linking in fhis process. The other methods use peroxide, multifunctional azide, or an organofunctional silane. Polyethylene resins respond to electron beam irradiation well since the rate of cross-linking exceeds significanfly fhe chain scission. Polypropylene (PP) is prone to P-cleavage, which makes if difficult to cross-link by a free radical process. For fhaf reason, PP resins... 

Celanese enjoys the major share of the merchant plastic milk bottles business in the United States because of this engineered high-density polyethylene resin. 

Figure 9.5-11. Viscosity behaviour of various polyethylene resins. Solid line, mPE dashed line, LDPE dotted line, LLDPE.

Pentachlorophcnol Petroleum wax Phenolic rerint-Novalak resin Pine rosin Polyethylene resins Polystyrene tedns Polypropylene-maleic anhydride Potassium nitrate Resins... 

High pressure low density polyethylene resins are produced in two types of reactors. One is a continuous-flow mechanically stirred autoclave (origi-... 

Traditionally, bimodal polyethylene resins are produced with a Ziegler-Natta (Z-N) type catalyst, but for specialty grades (e.g. bimodal LLDPE) the... 

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