Polyethylene Ziegler resins

PS PSF PSU PTFE PU PUR PVA PVAL PVB PVC PVCA PVDA PVDC PVDF PVF PVOH SAN SB SBC SBR SMA SMC TA TDI TEFE TPA UF ULDPE UP UR VLDPE ZNC Polystyrene Polysulfone (also PSU) Polysulfone (also PSF) Polytetrafluoroethylene Polyurethane Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) poly(vinyl butyrate) Poly(vinyl chloride) Poly(vinyl chloride-acetate) Poly(vinylidene acetate) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl fluoride) Poly(vinyl alcohol) Styrene-acrylonitrile copolymer Styrene-butadiene copolymer Styrene block copolymer Styrene butadiene rubber Styrene-maleic anhydride (also SMC) Styrene-maleic anhydride (also SMA) Terephthalic acid (also TPA) Toluene diisocyanate Ethylene-tetrafluoroethylene copolymer Terephthalic acid (also TA) Urea formaldehyde Ultralow-density polyethylene Unsaturated polyester resin Urethane Very low-density polyethylene Ziegler-Natta catalyst... 

The second type of solution polymerization concept uses mixtures of supercritical ethylene and molten PE as the medium for ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization in supercritical ethylene at high pressure (see Olefin POLYMERS,LOW DENSITY polyethylene) were converted for the catalytic synthesis of LLDPE. Both stirred and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C can also be used for this purpose. Residence times in these reactors are short, from 1 to 5 minutes. Three types of catalysts are used in these processes. The first type includes pseudo-homogeneous Ziegler catalysts. In this case, all catalyst components are introduced into a reactor as hquids or solutions but form soHd catalysts when combined in the reactor. Examples of such catalysts include titanium tetrachloride as well as its mixtures with vanadium oxytrichloride and a trialkyl aluminum compound (53,54). The second type of catalysts are soHd Ziegler catalysts (55). Both of these catalysts produce compositionaHy nonuniform LLDPE resins. Exxon Chemical Company uses a third type of catalysts, metallocene catalysts, in a similar solution process to produce uniformly branched ethylene copolymers with 1-butene and 1-hexene called Exact resins (56). 

In the mid-1950s a number of new thermoplastics with some very valuable properties beeame available. High-density polyethylenes produced by the Phillips process and the Ziegler process were marketed and these were shortly followed by the discovery and rapid exploitation of polypropylene. These polyolefins soon became large tonnage thermoplastics. Somewhat more specialised materials were the acetal resins, first introduced by Du Pont, and the polycarbonates, developed simultaneously but independently in the United States and Germany. Further developments in high-impact polystyrenes led to the development of ABS polymers. 

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. 

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

Corporation film-grade Ziegler-Natta linear low density polyethylenes will be presented. They are Resin E, Nova FP-015-A, MFI = 0.55, p = 0.9175 g/cc, and Resin C, Nova PF-120-F, MFI = 1.00, p = 0.9170 g/cc. Their capillary-flow behavior in terms of apparent shear stress vs. apparent shear rate are shown on Fig. 12.24. The melt fracture onset is also noted in Figure 12.24 and the data presented in the table below, indicate that resin E undergoes both sharkskin and gross melt fracture at lower apparent shear rates and stresses. 

Ultrahigh-molecular-weight polyethylene (UHMWPE) is defined by ATM as polyethylene with molecular weight over three million (weight average). The resin is made by a special Ziegler-type polymerization. 

Chem. Descrip. Cryst. oxidized Ziegler-type polyethylene wax CAS 68441-17-8 EINECS/ELINCS 200-815-3 Uses Lubricant wax PVC lubricant for transparent prods. in anionic emulsions to carry nonemulsifiable microwaxes, paraffins, etc. melting agent, water repellent in paints abrasion-resist, printing inks mixed saponified polishes preservative in textiles for crosslinking with wash-and-wear resins process aid and mold release in rubber compds. improves filler disp. corrosion inhibitor Features Hard, high-melting... 

Figure 2.7 A graphical summary of the different types of commercial polyethylene resins made with Ziegler-Natta and metallocene catalysts. MWDs are shown as solid lines and a-olefin comonomer fractions are depicted as dotted lines.

Perhaps one of the greatest contributions of Tref to the understanding of olefin polymerization was the elucidation of the natiue of active sites present on heterogeneous Ziegler-Natta catalysts. The systematic apphcation of Tref to ethylene/1-olefin copolymers made with heterogeneous Ziegler-Natta catalysts in different polymerization processes has shown that aU these resins have a signature bimodal Tref peak that can only be explained by the presence of two or more distinct types of active sites on the catalyst [34]. In contrast, low-density polyethylene (LDPE) made with the free-radical mechanism has a much narrower and unimodal Tref profile (Fig. 18), as expected from a free-radical polymerization mechanism. 

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