Crystalline Ethylene

In 1958 the Union Carbide Corporation introduced high molecular weight, highly crystalline ethylene oxide polymers under the trade name Polyox. Although similar in appearance to polyethylene they are miscible with water in all proportions at room temperature. 

A preferred way to enhance the crystalline domain formation of ethylene in the EVA polymer is to delay the addition of vinyl acetate during the polymerization process such that the unreacted vinyl acetate level present in the reactor is minimal at different stages during the process. Thus, the copolymerization can take place in the initial stage, where most of the ethylene will reside in amorphous regions, and the formation of the majority of crystalline ethylene domains can occur in the later stage of the polymerization process. 

Instead, the distribution of vinyl acetate and ethylene in the copolymer is a major factor. A sufficient level of amorphous ethylene vinyl acetate polymer segments is needed in order to provide adhesion to a substrate. Further, a sufficient level of crystalline ethylene polymer segments is needed to provide the proper balance of heat seal characteristics and non-blocking. 

J.J. Rabasco, C.L. Daniels, D.W. Horwat, M.S. Vratsanos, and R.H. Bott, Semi-crystalline ethylene vinyl acetate emulsion polymers for heat seal applications, US Patent 7189461, assigned to Air Products Polymers, L.P. (Allentown, PA), March 13,2007. 

J.J. Rabasco, G.J. Dearth, C.R. Hegedus, F.R. Pepe, and B.V. Mukku-lainen, Masonry sealing compositions comprising semi-crystalline ethylene-vinyl acetate polymer emulsions, US Patent 7459186, assigned to Wacker Chemical Corporation, December 2, 2008. 

Based on the above principle we provide the following examples (/) the elimination of some crystalline dihalogeno-adipates and dihalogeno-cyanobutanes with gaseous amines, ( ) the heterogeneous addition of bromine to crystalline ethylenes. 

Dauber, P., Brith, M., Huler, E. and Warshel, A. (1975) The Vibronic Structure of Crystalline Ethylene, Chem. Phys. 7, 108-115. 

Kreituss, A. and Frisch, H.L. (1981) Free volrnne estimates in heterogeneous polymer systems. 1. Diffusion in crystalline ethylene-propylene copxilymers. /. 

Anderson and Haslewood (19) explored the preparation of these derivatives from 3 -hydroxy-6-keto-5rt-cholanoic acid in a manner analogous to that outlined in Fig. 6. The known 3a,7 -dihydroxy-6-keto-5a-cholanoic acid (90) was esterified, and the product converted to a crystalline ethylene thioketal. Treatment of the latter with Raney nickel provided allolithocholic acid and several fractions of unidentified material. From one of these fractions an acid (A) was obtained, m.p. 240-241 °C [ ]D+60i 1 from the succeeding fraction an acid (B) was converted to the methyl ester (C), m.p. 156-158°C [a]D4-58 1 °. The Md for (C) (Found-1-235) agrees reasonably well with the calculated value for a 3/3,7(3-diol (4-190) or a 3a,7 3-diol (4-197). In a similar sequence of reactions Ziller (91) obtained a methyl ester, m.p. 158-159°C RRe 1.42 on 3% QF-1 free acid, m.p. 240-241 °C. Subsequent experiments have shown that the monohydro.xy acids derived from this diol are the 3p- and 7 -ols, suggesting that this acid is the unreported 3j3,7/3-dihy-droxy-5a-cholanoic acid (170). 

Fig. 4. Dynamic mechanical loss spectra of (a) Three semicrystalline ethylene-co-styrene polymers having different wt% comonomer compositions, (b) Amorphous or low crystallinity ethylene-co-styrene polymers. (The label ES refers to a copolymer having ...

A series of high-cis B-I-B triblock copolymers were prepared with lanthanide catalysts by incremental monomer addition. TTie hydrogenated products lead to E-(E/P)-E triblock copolymers with hard (semi-crystalline) ethylene block at both chain ends and soft (amorphous rubbery) alternating E/P block in the center segment. 

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