Ethylene, copolymers with methacrylic acid

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. 

Acryhc stmctural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acryhc adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated stmctural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, N,1S7-dimethyl- -toluidine, and saccharin, can be apphed to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

A variety of ionomers have been described in the research literature, including copolymers of a) styrene with acrylic acid, b) ethyl acrylate with methacrylic acid, and (c) ethylene with methacrylic acid. A relatively recent development has been that of fluorinated sulfonate ionomers known as Nafions, a trade name of the Du Pont company. These ionomers have the general structure illustrated (10.1) and are used commercially as membranes. These ionomers are made by copolymerisation of the hydrocarbon or fluorocarbon monomers with minor amounts of the appropriate acid or ester. Copolymerisation is followed by either neutralisation or hydrolysis with a base, a process that may be carried out either in solution or in the melt. 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

Ionomers are generally ethylene copolymers with 5-10 percent of methacrylic acid, half-neutralized by sodium or zinc. 

Ionomers consist of statistical copolymers of a non-polar monomer, such as ethylene, with (usually) a small proportion of ioniz-able units, like methacrylic acid. Ethylene-co-methacrylic acid copolymers (-5% methacrylic acid) are used to make cut-proof golf balls (see Fascinating Polymers opposite). The protons on the carboxylic acid groups are exchanged with metal ions to form salts. These ionic species phase-separate into microdomains or clusters which act as crosslinks, or, more accurately, junction zones (Figure 6-4). (We discuss interactions in a little more detail in Chapter 8.)... 

Fig. 1. X-ray diffraction from (a) branched polyethylene, (b) copolymer of 94% ethylene and 6% methacrylic acid, and (c) sodium salt of copolymer in (b), 90% neutralized, (reprinted with permission from ref 64)...

Because the free radical initiated graft reaction can also lead to the cross-linking of polyethylene, copolymers of ethylene and with acrylic acid (184,185), glycidyl methacrylate (184,186), methacrylic acid and 10-undecenoic acid (187-189) were synthesized to compatibilize polyethylene/polyamide blends. The poly (ethylene-co-methacrylic acid) ionomers neutralized by sodium (184) and zinc (45,118,190-192) has also used as compatibilizers. High energy irradiation, used to modify the surface of fibers or films at beginning, was also used to compatibilize the polyethylene/polyamide blends (193-196). 

This chapter covers the applications of Fourier transform infrared (FTIR) and Raman spectroscopy to the characterization of water-soluble polymers. The structural analysis of poly(oxyethylene), poly ethylene glycol), poly methacrylic acid), and poly acrylic acid), and the interactions of selected polymers with solvents and surfactants are presented. Structural features of these compounds in the crystalline and melt states are compared with their structural features upon dissolution in aqueous solvents. Special emphasis is given to the recent studies of the interactions between water-soluble polymers or copolymers and solvents or surfactants. New experimental approaches and the sensitivities of both FTIR and Raman spectroscopy to monitor such interactions are presented. 

Amongst copolymers of PE, there are polyallomers (ethylene-propylene copolymers), copolymers with cyclo-olefins and with vinylic monomers [with vinyl acetate ethylene-vinyl acetate, (EVA), with methacrylic acid, MA, and with vinyl alcohol ethylene - vinyl alcohol, (EVOH)], and chlorinated PE (CPE). CPE, although it exhibits exceptional UV and chemical resistance, gives rise to a high amount of hydrogen chloride gas evolution if combusted. 

Copolymers maleic anhydride copolymer with ethylene or vinyl methyl ether, acrylic acid copolymers, and methacrylic acid copolymers (Eudragit)... 

GENERAL INFORMATION The Surlyn brand of ionomers consists of copolymers of ethylene with methacrylic acid, partially or wholly neutralized with a variety of metals, including sodium, zinc, and lithium.The neutralization process drastically increases the melt viscosity and decreases the solubility, making molecular weight determinations of the final product impossible. However, the metal ions can be removed by treatment with acids, and the unneutralized copolymer examined by methods similar to those used for low density polyethylene (LDPE) and copolymers thereof. In certain cases, the properties of the ionomer resemble LDPE where applicable, these values are given in italics. About twenty grades of Surlyn plastics exist. Here we report on two representative samples sodium (Na) neutralized and zinc (Zn) neutralized. Where experimental conditions are described by a "D-" number, these refer to test procedures of the American Society for Testing Materials. 

The grafting functionalization of a poly(vinylidene fluoride) powder by y-irradiation was achieved by Valenza et aL The amoimt of grafted meth-acrylic acid onto poly(vinylidene fluoride) (PVDF) powder was 19.7 w%. The grafted polymer was then blended at different ratios with an ionomer based on ethylene-methacrylic acid copolymer, partially neutralized (Surlyn 9970). Nongrafted PVDF and this ionomer are highly immiscible. The functionalization of the PVDF with methacrylic acid allows to compatibilize both... 

The hydrogel membrane is a copolymer of N-isopropylacrylamide (NIPA) doped with methacrylic acid (MAA) and cross-linked with small amounts of ethylene glycol dimethacrylate (EGDMA). The prepolymer solution containing the monomers at the desired concentrations is poured between two glass plates separated by a 250 pm spacer. Polymerization is initiated using a combination of ammonium persulfate as free radical generator and tetraethylene-methylenediamine as accelerator. 

Much of the work reported in the academic literature is based upon microgels prepared from poly(NIPAM), but there are, however, a number of microgels that have been prepared from other monomers. These include methyl methacrylate with other copolymers such as ethylene glycol dimethacrylate (17,18), methyl methacrylate with p-divinylbenzene (19), and methyl methacrylate with methacrylic acid (20). Other microgel particles have been prepared from poly(allylamine hydrochloride) (21), vinylpyrrolidinone and acrylic acid (22), acrylamide and acrylamide with methacrylamidopropyltrimethylammonium chloride (23), and acrylamide copolymerized with 2-acrylamido-2-methylpropanesulfonic acid (24). 

For the purposes of this chapter, acrylic polymers are defined as polymers based on acrylic acid and its homologues and their derivatives. The principal commercial polymers in this class are based on acrylic acid itself (I) and methacrylic acid (II) esters of acrylic acid (III) and of methacrylic acid (IV) acrylonitrile (V) acrylamide (VI) and copolymers of these compounds. Copolymers of methacrylic acid and ethylene are described in Chapter 2. The important styrene-acrylonitrile and acrylonitrile-butadiene-styrene copolymers are discussed in Chapter 3 whilst acrylonitrile-butadiene copolymers are dealt with in Chapter 18. 

Copolymer of methacrylic acid with dimethacrylate of ethylene glycol + 4ml of hexane, 1 4 M1E4H4X - washed with methanol after the synthesis. 

The structure of homogeneous PHEMA, that is materials polymerized in solutions with less than approximately 45 wt. % water in the reaction mixture 28), has been examined in greater detail. The earliest estimate of pore size in these PHEMA materials was 0.4 nm for a polymer prepared in the presence of water and ethylene glycol was provided by Refojo 29) who used the relationship between water permeability and average pore diameter developed by Ferry 30). The materials investigated by Refojo contained 39 wt. % water. This method was later applied by Haldon and Lee (57) to similar PHEMA samples of 41-42 wt. % hydration to obtain a pore radius between 0.4 and 0.8 nm. It was acknowledged that the assumptions implicit in the use of the Ferry equation resulted in underestimation of the pore size. This was highlighted by the observation that sodium fluorescein, with a radius of 0.55 nm, could readily diffuse into PHEMA. Later Kou et al. 32) demonstrated that solutes of radius 0.6 nm were able to penetrate PHEMA and copolymers of HEMA with methacrylic acid, and that the rate of diffusion was consistent with free volume theory. 

An adipic acid-diethylene glycol copolymer, by treatment with a THF polymer or polypropylene glycol in the presence of chlorosulfonic acid, afforded polyether polyesters useful for the preparation of thermoplastic block copolyester rubbers and polyurethans. Strongly acid sulfonate derivatives of hydrophilic polymers may be prepared by reacting glycidyl methacrylate-ethylene dimethacrylate copolymer or ethylene dimethacrylate-glycidyl methacrylate-styrene copolymer with chlorosulfonic acid or oleum at 0-60 °C. ... 

Measurements were also carried out for three series of copolymers copolymers of styrene with methacrylic acid (S-MAA) and crosslinked copolymers of the styrene and divinylbenzene (S-DVB), those of methyl methacrylate and dimethacrylate ethylene glycol (MMA-DMEG) as well as for the set of oligom-ethacrylates, oligocarbonat and oligo-a-methyl styrenes. The preparation of samples and experimental technique were described in [31-33],... 

Within the scope of the original definition, a very wide variety of ionomers can be obtained by the introduction of acidic groups at molar concentrations below 10% into the important addition polymer families, followed by partial neutralization with metal cations or amines. Extensive studies have been reported, and useful reviews of the polymers have appeared (3—8). Despite the broad scope of the field and the unusual property combinations obtainable, commercial exploitation has been confined mainly to the original family based on ethylene copolymers. The reasons for this situation have been discussed (9). Within certain industries, such as flexible packaging, the word ionomer is understood to mean a copolymer of ethylene with methacrylic or acryhc acid, partly neutralized with sodium or zinc. 

Ionomer resins consisting of ethylene—methacrylic acid copolymers partially neutralized with sodium or zinc were commercially introduced in 1964 by Du Pont under the Sudyn trademark (1). More recently, a similar line of products, sold as Hi-Mdan resins, has been commercialized by Mitsui—Du Pont in Japan. lolon ionomeric resins, based on ethylene—acrylic acid, are produced by Exxon in Belgium. Ionomers containing about 1 mol % of carboxylate groups are offered by BP in Europe as Novex resins. Low molecular weight, waxy Aclyn ionomers are produced and sold by AHiedSignal. 

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