Molecular weight ionomers

Pigment dispersants are low molecular weight ionomers that can promote good pigment dispersion and come within the regulations of many countries for colour concentrates... 

AClyn, Low molecular weight ionomers, AlliedSignal Inc., AlliedSignal Specialty Chemicals... 

AlliedSignal s Aclyn range of low molecular weight ionomer colour dispersants is claimed to offer improvements in division as well as wetting and... 

However, when the metals ions were placed at both ends of the ehain in the a,(o-(metal carboxylate) PLA, the Tg values of both molecidar weights crossed over, because of the higher effective cross-link density for the lower molecular weight ionomer. 

SAXS data for the 2.5M-SPS ionomers are shown in Fig. 5. A distinct scattering peak was observed in the metal salt ionomers, that corresponded to a characteristic size in real space of 5 nm. That peak is consistent with similar peaks observed by SAXS of high molecular weight ionomers and is due to nanophase separation of ion-rich aggregates. That conclusion is also supported by the fact that the intensity of the peak in Fig. 5 increased proportionally to the electron density of the cation used. The characteristic size in these materials is believed to related to the separation between ionic aggregates. No SAXS peak was observed for PS or the H-SPS. The latter result may indicate that either the hydrogen bonding interactions in that polymer were too weak to drive... 

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. 

Fig. 1. Stress—strain curves for ionomer and polyethylene resins. Test speed is 5 cm/min. The reference matedal is high molecular weight conventional...

Telechelic Ionomers. Low molecular weight polymers terminated by acid groups have been treated with metal bases to give ionomers in which the cations can be considered as connecting links in the backbones (67—71). The viscoelastic behavior of concentrated solutions has been linked to the neutralizing cation. 

Hill, R. G., Wilson, A. D. Warrens, C. P. (1989). The influence of poly(acrylic acid) molecular weight on the fracture toughness of glass-ionomer cements. Journal of Materials Science, 24, 363-71. 

Wilson, A. D., Crisp, S. Abel, G. (1977). Characterization of glass-ionomer cements. 4. Effect of molecular weight on physical properties. Journal of... 

Polymer gels and ionomers. Another class of polymer electrolytes are those in which the ion transport is conditioned by the presence of a low-molecular-weight solvent in the polymer. The most simple case is the so-called gel polymer electrolyte, in which the intrinsically insulating polymer (agar, poly(vinylchloride), poly(vinylidene fluoride), etc.) is swollen with an aqueous or aprotic liquid electrolyte solution. The polymer host acts here only as a passive support of the liquid electrolyte solution, i.e. ions are transported essentially in a liquid medium. Swelling of the polymer by the solvent is described by the volume fraction of the pure polymer in the gel (Fp). The diffusion coefficient of ions in the gel (Dp) is related to that in the pure solvent (D0) according to the equation ... 

A variation of the lamellar model was recently proposed by Haubold et al., in which synchrotron SAXS studies were performed on acid form Nafion 117 samples. The molecular weight of these samples was reported to be 250 000 g mol and the experiments were conducted on dry samples in air and samples equilibrated with water, methanol, and a range of water/methanol mixtures using an in situ flow cell. The most fundamental result of this study is that the data show the usual ionomer peak at = 1.4 nm which gives a Bragg spacing of d= Zjtlq ... 

The Surlyn A ionomers (E. I. du Pont de Nemours Co.) are believed to be derived from copolymers of ethylene with minor amounts of methacrylic acid which are treated subsequently, so that substantial amounts of the carboxylic acid are converted to the sodium or other metal carboxylate. Resins similar to the one studied in this work contain about 10 weight % methacrylic acid. The ash (sodium carbonate) indicates about 40% neutralization. This resin, which contains 0.05% Santo-white Powder (Monsanto Chemical Co.), a phenolic antioxidant, is of medium molecular weight—i.e., probably corresponding to an ethylene homopolymer with a melt flow index around 20 (17). The molecular weight distribution is broad (17). 

Experiments indicate that the critical strain-to-failure is also affected by the average molecular weight and by material processing history. McGrath40 reported strain-to-break of a non-crystalline ionomer (a poly(arylene-ether) random copolymer, biphenyl sulfone in H form, or bi-phenyl sulfone in H form (BPSH)) is proportional to the length of the chain. We found in our laboratory that the casting procedure also affects the strain-to-break of the solution-cast ionomer film. As shown in Fig. 19, a Nation film cast at near room... 

Within the family of polyolefins there are many individual families that include low density polyethylenes, linear low density polyethylenes, very low polyethylenes, ultra low polyethylenes, high molecular weight polyethylenes, ultra high molecular weight polyethylenes, polyethylene terephthalates, ethylene-vinyl acetate polyethylenes, chlorinated polyethylenes, crosslinked polyethylenes, polypropylenes, polybutylenes, polyisobutylene, ionomers, polymethylpentene, thermoplastic polyolefin elastomers (polyolefin elastomers, TP), and many others. 

Polymer 2 dissolves slowly in 98% sulfuric acid without degradation of molecular weight, and is sulfonated regiospecifically and quantitatively to give ionomer 9. This material, unlike the parent polymer 7, is strongly hydrophilic and dissolves readily in... 

Figure 10. Cumulative number of molecules in clusters in hydrated SSC PFSA ionomer and Nafion for Rc = 3.5 A as a function of molecular weight - 15mer (gray) and trimer (black).

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