Other Ethylene Copolymers

More industrial polyethylene copolymers were modeled using the same method of ADMET polymerization followed by hydrogenation using catalyst residue. Copolymers of ethylene-styrene, ethylene-vinyl chloride, and ethylene-acrylate were prepared to examine the effect of incorporation of available vinyl monomer feed stocks into polyethylene [81]. Previously prepared ADMET model copolymers include ethylene-co-carbon monoxide, ethylene-co-carbon dioxide, and ethylene-co-vinyl alcohol [82,83]. In most cases,these copolymers are unattainable by traditional chain polymerization chemistry, but a recent report has revealed a highly active Ni catalyst that can successfully copolymerize ethylene with some functionalized monomers [84]. Although catalyst advances are proving more and more useful in novel polymer synthesis, poor structure control and reactivity ratio considerations are still problematic in chain polymerization chemistry. 

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For the sake of brevity detailed tables of all tests performed are shown for duPont ionomer resins only (Tables II, III, IV, VI to X). The other ethylene copolymers were similarly treated and evaluated. The effects of increasing radiation dosages on certain physical properties of selected duPont ionomers are shown graphically in Figures 1, 2, and 3. 

To improve dyeability, flexibility, and toughness of isotactic polypropylene, PP, it was compounded in a Banbury-type mixer with ethylene-vinyl acetate, 7 wt% EVAc. Several other ethylene copolymers were also used. In Miliprint patent, EVAc or ethylene-ethyl acrylate copolymer, 18-32 wt% EVAc or EEA, was found to improve impact strength, elongation, and low brittleness temperature of PP. hi Firestone patent, linear polybutadiene, BR, was used. The Mitsubishi patent disclosed improvements of PP impact strength properties by blending it with 0.5-25 wt% ethylene-aliphatic esters, e.g., EVAc... 

The Dow Chemical Company developed the solution polymerization process with the Dowlex tradename in the 1970s to manufacture ethylene/1-octene linear low-density polyethylene (LLDPE) copolymers. The process is proprietary and not available for license. The ethylene/1-octene copolymers exhibit many superior physical properties relative to other ethylene copolymers based on 1-butene or 1-hexene. 

Other ethylene copolymers that have been studied include those with vinyl alcohol [64], acrylates [65] tetrafluoroethylene [66], 4-methyl pentene [67, 68], propylene - vinyl chloride [69], ethylene vinyl cyclohexane [70] and ethylene - vinyl acetate [71]. 

In contrast to other polymers the resistance to water permeation is low due to the hydrolysis of the poly(vinyl acetate) (163,164). Ethylene copolymers have been developed which have improved water resistance and waterproofness. The polymer can be used in the latex form or in a spray-dried form which can be preblended in with the cement (qv) in the proper proportion. The compressive and tensile strength of concrete is improved by addition of PVAc emulsions to the water before mixing. A polymer-soHds-to-total-soHds ratio of ca 10 90 is best. The emulsions also aid adhesion between new and old concrete when patching or resurfacing. 

Extension of the chlorosulfonation technology to base resins other than polyethylene, where value can be added, seems a logical next step. Polypropylene and ethylene copolymers containing additional functionaUty, ie, maleic anhydride graft, vinyl acetate, acrylic acid, etc, have been chlorinated and chlorosulfonated to broaden the appHcation base, particularly in coatings and adhesives (9,10). 

Specialty waxes include polar waxes for more polar adhesive systems. Examples would be castor wax (triglyceride of 12-hydroxy stearic acid) or Paracin wax N- 2 hydroxy ethyl)-12-hydroxy stearamide) which are used in polyester, polyamide, or with high VA EVA copolymer-based systems. Other common polar waxes are maleated polyethylenes, which are used to improve the specific adhesion of polyethylene-based adhesives, and low molecular weight ethylene copolymers with vinyl acetate or acrylic acid, which are used to improve low temperature adhesion. High melting point isotactic polypropylene wax (7 155°C) and highly refined paraffin wax (7,n 83°C) are used where maximum heat resistance is critical. Needless to say, these specialty waxes also command a premium price, ranging from 2 to 5 times that of conventional paraffin wax. 

RAFT polymerization has been used to prepare poly(ethylene oxide)-/ /wA-PS from commercially available hydroxy end-functional polyethylene oxide).4 5 449 Other block copolymers that have been prepared using similar strategies include poly(ethylene-co-butylene)-6/oci-poly(S-eo-MAH), jl poly(ethylene oxide)-block-poly(MMA),440 polyethylene oxide)-Moe -poly(N-vinyl formamide),651 poly(ethylene oxide)-Wot A-poly(NlPAM),651 polyfethylene ox de)-b ock-polyfl,1,2,2-tetrahydroperfluorodecyl acrylate),653 poly(lactic acid)-block-poly(MMA)440 and poly( actic acid)-6focA-poly(NIPAM),4 8-<>54... 

To illustrate the potential of the method, we present in Figure 7 the 2D ESRI perspective plot of a phantom sample consisting of nitroxide biradicals derived from Tinuvin 770 (obtained by oxidation of the amine) in two different environments in a plaque of heterophasic propylene-ethylene copolymers (HPEC). One side of the plaque was doped with the biradical by contact with a biradical solution in toluene. The same biradical solution was placed on transparent tape and the solvent was evaporated the tape was then folded and attached to the other side of the plaque. The corresponding spectral slices are... 

Other commercial copolymers which are typically random are those of vinyl chloride and vinyl acetate (Vinylite), isobutylene and isoprene (butyl rubber), styrene and butadiene (SBR), and acrylonitrile and butadiene (NBR). The accepted nomenclature is illustrated by EP, which is designated poly-ethylene-co-propylene the co designating that the polymer is a copolymer. When the copolymers are arranged in a regular sequence in the chains, i.e., ABAB, the copolymer is called an alternating copolymer. A copolymer consisting of styrene and maleic anhydride (SMA) is a typical alternating copolymer. 

Many membrane materials have been developed and are used for hemodialyzers. Today, these include regenerated cellulose, cellulose acetate, polyacrylonitrile, poly(methylmethacrylate), vinyl alcohol-ethylene copolymer, polysulfone, polyamide, and others. 

Low density poly(ethylene) (LDPE) may have unsatisfactory heat seal properties, as they often do not provide sufficient adhesion between the sealing layers to result in a good adhesive seal for a package. Efforts to improve the heat seal characteristics of LDPE by blending them with other materials, such as ethylene copolymers with methacrylic acid or acrylic acid, have not had universal success. 

Each set of experiments was carried out under the same reaction condition except using different comonomers, i.e. p-methylstyrene, o-methylstyrene, m-methylstyrene and styrene, respectively. The compositions of copolymers were determined by H NMR spectra, and the thermal properties (melting point and crystallinity) were obtained by DSC measurements. Overall, all comonomers show no retardation to the catalyst activity. In fact, the significantly higher catalyst activities were observed in all copolymerization reactions (runs 2-5), comparing with that of ethylene homopolymerization (run 1). Within each set (runs 2-5 and 6-9) of comparative experiments, p-methylstyrene consistently shows better incorporation than the rest of comonomers, i.e. o-methylstyrene, m-methylstyrene and styrene. Both catalysts with constrained mono- and di-cyclopentadienyl ligands are very effective to incorporate p-methylstyrene into polyethylene backbone. In runs 2 and 6, more than 80 % of p-methylstyrene were converted to copolymer within one hour under constant (- 45 psi) ethylene pressure. On the other hand, only less than half of styrenes (runs 5 and 9) were incorporated into ethylene copolymers under the same reaction conditions. The significantly... 

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