Ethylene-Methacrylic Acid Copolymers Ionomers

Zinc neutralized, ethylene-methacrylic acid copolymer ionomer Zinc carboxylate Low reactivity with amine but good polar interaction of Zn with amide and amine groups (interfacial complexation) Tg not low cmough, limits low temp, toughness Good solvent resistanee... 

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. 

Ionomer. Ionomer is the generic name for polymers based on sodium or zinc salts of ethylene-methacrylic acid copolymers in which interchain ionic bonding, occurring randomly between the long-chain polymer molecules, produces solid-state properties. 

Figure 17 shows the infrared spectra (from 1900 to 1200 cm-1) of the completely ionized calcium ionomer of an ethylene-methacrylic acid copolymer recorded at room temperature (a) and the same film recordered at 40, 70, 130, and 150 °C (b-e, respectively). This recording of the spectra at the elevated temperatures accentuates the sharp doublet at 1515/1548 cm which is characteristic of an interaction or vibrational splitting of the pairs of COO" groups. 

The first commercial ionomers were introduced in the mid-1960s when Dupont produced an ethylene/methacrylic acid copolymer under... 

The ionic aggregates present in an ionomer act as physical crosslinks and drastically change the polymer properties. The blending of two ionomers enhances the compatibility via ion-ion interaction. The compatibilisation of polymer blends by specific ion-dipole and ion-ion interactions has recently received wide attention [93-96]. FT-IR spectroscopy is a powerful technique for investigating such specific interactions [97-99] in an ionic blend made from the acid form of sulfonated polystyrene and poly[(ethyl acrylate - CO (4, vinyl pyridine)]. Datta and co-workers [98] characterised blends of zinc oxide-neutralised maleated EPDM (m-EPDM) and zinc salt of an ethylene-methacrylic acid copolymer (Zn-EMA), wherein Zn-EMA content does not exceed 50% by weight. The blend behaves as an ionic thermoplastic elastomer (ITPE). Blends (Z0, Z5 and Z10) were prepared according to the following formulations [98] ... 

Reference 7 reviews a number of electron microscopy studies of ionomer morphology in the period up to 1979. None of these studies makes a convincing case for the direct imaging of ionic clusters. This is because of the small size of the clusters (less than 5 nm based on scattering studies) and difficulties encountered in sample preparation. The entire problem was reexamined in 1980(21). In this study ionomers based on ethylene-methacrylic acid copolymers, sulfonated polypentenamer, sulfonated polystyrene and sulfonated ethylene-propylene-diene rubber (EPDM) were examined. The transfer theory of imaging was used to interpret the results. Solvent casting was found to produce no useful information about ionic clusters, and microtomed sections showed no distinct domain structure even in ionomers neutralized with cesium. Microtomed sections of sulfonated EPDM, however,... 

Commercial ionomers are ethylene-methacrylic acid copolymers and terpolymers in which the carboxylic acid moiety is partially neutralized with sodium or zinc, to promote interchain ionic bonding. Ionomers exhibit excellent low temperature toughness, chemical resistance and adhesion. However they lack in stiffness and heat resistance. Hence ionomer blends with polyolefins such as polyethylene have been developed which, upon reinforcing with suitable fillers, seem to give a unique combination of high strength, excellent low temperature toughness, and moderate stiff-... 

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... 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

LDPE/PA6 blends with ethylene-methacrylic acid copolymer Na salt ionomer as compatibilizer Thermal stability of blends using TGA TGA measurements demonstrated an improvement in thermal stability when iratomer was added Labor et al. 2004... 

PE was blended with ethylene-methacrylic acid copolymer, 80 wt% ionomer, and ethylene-vinyl acetate, 10 wt% EVAc, for films with high toughness, stiffness, and impact resistance ... 

Recent work on crystallinity measurements is reported below sulfur containing ether ketones [14], polyethylene glycol [15], polystyrene (PS) [16, 17], (PC) [18], polyphenylene alkene diyls [19, 20], isotactic polypropylene [20, 21], polyethylene [21, 22], polyimide [23], poly(2,5 bis (4-methoxyphenyl) oxycarbonyl styrene [24], polyazomethine esters [25], PET-polybutylene terephthalate blends [26], polycyclohexyl ethylene copolymers [27], polycaprolactone [28], syndiotactic polystyrene [29, 30], polyvinylidene fluoride-trifluorethylene copolymer [30], polyethers [31], isotactic methyl methacrylate [32], soy protein isolate polymers [33], polyamide 6/66 [34], polytrimethylene-2,6-naphthalate [35, 36], PE like polyesters [37], polycyclohexadiene [38], p-dioxolone, L-lactide - polyethylene glycol copolymers [39], ethylene - methacrylic acid copolymers and ionomers [40]. 

Ali [89] reported the results of a study on a LDPE blend with an ionomer resin based on ethylene-methacrylic acid copolymer (Surlyn 1857 10 wt%), which also contained citric acid (1 wt%) as a blowing agent. The blend, as well as the reference samples of pure LDPE and LDPE/citric acid, were e-beam-irradiated at room temperature with a dose of 40kGy, and the EPR spectra were recorded at different time intervals after irradiation. The septet corresponding to allyl radicals was a dominant spectral component in the initial spectra, the total radical concentration being about 10% higher in the presence of the ionomer due to a contribution of Surlyn-derived radicals. The latter were more stable, such that in the blend the EPR signal was still observed three days after irradiation, whereas in the reference samples the radicals had decayed completely within 3.5 h. 

Nevertheless, several conunercial grades of moderate impact strength polyamides have been produced for a long time by simple melt blending with such impact modifiers as ethylene-ethyl acrylate, ethylene-acrylic acid copolymers and ionomers based on zinc neutralized, ethylene-methacrylic acid copolymers [15-16]. However, in the case of the PA-6, the zinc ionomers have been found to be particularly effective as impact modifiers... 

R. K. Shah and D. R. Paul. Comparison of nanocomposites prepared from sodium, zinc, and hthium ionomers of ethylene/methacrylic acid copolymers. Macromolecules, 39 (2006), 3327 3336. 

Similar mechanical data for a series of ionomers derived from a single ethylene—acryflc acid copolymer have appeared (13) (Table 3). Comparison of the data from Tables 2 and 3 shows that the substitution of acryflc acid for methacrylic acid has only minor effects on properties. 

Ethylene methacrylic acid (1-10%) copolymers are known as ionomers Some of the COOH groups are esterified in the commercial product. 

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.)... 

Neutralization of EAA or a similar copolymer, for example EMAA (ethylene methacrylic acid), with cations such as Na Zn Li produces a material that has better transparency, toughness, and higher melt strength than the unneutralized copolymer. These materials are called lonomers because they combine covalent and ionic bonds in the polymer chain. The structure of an ionomer of the ethylene sodium acrylate type is ... 

Neutralization of ethylene copolymers containing up to 5%-10% acrylic or methacrylic acid copolymer with a metal salt such as the acetate or oxide of zinc, magnesium, and barium yields products referred to as ionomers. (Commercial products may contain univalent as well as divalent metal salts.) lonomers are marked by Du Pont under the trade name Surlyn. These have interesting properties compared with the nonionized copolymer. Introduction of ions causes disordering of the semicrystalline structure, which makes the polymer transparent. lonomers act like reversibly cross-linked thermoplastics as a result of microphase separation between ionic metal carboxylate and nonpolar hydrocarbon segments. The... 

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