Ionomer Surlyn

The LOPE S were obtained from Monsanto (LDPE-M8011) and Dow Chemical (LDPE-493C) the poly(ethylene-co-methacrylic acid)) (Nucrel -1214) and ionomers (Surlyn -8660 and Surlyn -9950) were graciously provided by the Dupont Chemical Company. 

Ionomer (Surlyn) is a methacrylic acid and ethylene modified molecule with a metal ion (sodium, zinc, magnesium). Easy sealing, soft, strong, grease-resistant clear film, and seals well in contact with contaminants. Puncture-resistant, with a high hot tack. Approximately double the price of LDPE, but can be used in thinner gauges. Can be used in the inner ply of laminates, at approx, gauge of LDPE and as a skin pack over sharp or pointed objects. 

Ethylene copolymer ionomers Surlyn E. I. du Pont de Nemours Co. 

Appiications adhesives, footwear, glass coating, metal coating, modification of surface properties of films and coatings refrigerated food packaging, wire and cable ionomer (Surlyn) golf ball covers, hockey helmets, ski boots ... 

Compatibie poiymers - ionomer (Surlyn), ethylene-methacrylic acid-acrylate terpolymer (Nucrel), PBT, PE, PEO, PET ... 

The second polymer studied by Shah was an ionomer (Surlyn 8945). Figure 4.5 contains the relative permeabilities for the ionomer nanocomposite compared to the tortuous path model predictions for an aspect ratio 120. The agreement between the tortuous path model and experimental is quite good. The generally accepted aspect ratio for this particular clay is about 150, which is close to the 120 utilized in the figures. The clay in the ionomer appears to be more fully exfoliated, which is consistent with the higher percent increase in modulus measured for the ionomer nanocomposite relative to the FDPE. 

The linkage between two chains can also be ionic. Thus the copolymer between ethylene and methacrylic acid (MA) (up to 15% MA), made by free radical polymerisation, yields a polymer with pendant carboxyl groups. Neutralisation with zinc ions gives a crosslinked, thermo-reversible polymer (Surlyn ). The resulting polymer (ionomer) has limited properties, although it is the favoured material for the outer covering of golf balls. 

The stiff regions observed in the studies of McLean et al. were assigned to fluorocarbon crystalline domains, the size of which was around 10 nm. The crystalline packing was referred to as lamellae which are not organized into stacks, as is the case for the Surlyn ionomers that were studied. An interesting outcome of the normal tapping studies was the discovery of a very thin ( 5 A) fluorine-rich layer over the surface in which the contrasted soft regions are amorphous. 

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). 

In view of the similarity in behavior of the networks in the ionomer and low density resin, we are able to deduce from modulus and elongation at rupture measurements the relative crosslinking rates. It appears that Surlyn A crosslinks 50 to 60% more rapidly than DFD 6040. The increased crosslinking in the ionomer may be associated with the radio-... 

Mechanical Properties. Table I shows the general range of mechanical properties available in commercial Surlyn ionomers. Tile substitution of acrylic acid fur methacrylic acid has only minor effects on properties. 

During processing at elevated temperatures, normal precautions are needed to prevent accidental bums. Surlyn ionomers have U.S. Food and Drug Administration clearance for food contact. 

Ionomer resins consisting of ethylene—methacrylic acid copolymers partially neutralized with sodium or zinc were commercially introduced in 1964 by Du Pont under the Surlyn trademark (1). More recently, a similar line of products, sold as Hi-Milan resins, has been commercialized by Mitsui—Du Pont in Japan. Iolon 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 AlliedSignal. 

Several organic sealants such as epoxy resins, butyl rubber or silicones prove to be more or less permeable and the tiny amount of solvent in the cell is rapidly lost. Suitable organic sealing materials for this technology turn out to be thermoplastic materials, like polyethylene/carboxylate copolymers. So far, Surlyn 1702 ionomer from Dupont has been the main substance used to optimize cell performance and build module prototypes. However, the softening point of Surlyn is rather low (65° C) and at elevated temperatures (> 70°C), serious solvent loss is observed because the bond between Surlyn and TCO-coated glass is substantially weakened [7]. 

Recent literature (72, 74) has indicated a considerable interest in blending ionomers (such as du Pont s Surlyn) with a variety of polymers. It is believed that an ionomer-nylon blend is the basis for a new engineering thermoplastic. 

Coidombic Interactions (Ionomers) 2 Long Range a /. Varies as Hr 10-20 kcaUmole Surlyn ... 

We will briefly introduce some important ionomers (see Fig. 1), but for a thorough treatment of ionomer chemistry, see, e.g., Refs. . The simplest classification of ionomers is semicrystalline vs. amorphous ionomers. The prototypical semicrystalline ionomer is EMAA (Surlyn, DuPont) neutralized with various cations. Also from DuPont, Nafion is a perfluorinated polyethylene with sulfonic acid or sulfonate groups on short side chains. Other commercial ionomers like Aciplex (Asahi Chemical Company), Flemion (Asahi Glass Company), and Neosepta (Tokuyama) are structurally similar to Nafion. For a recent review on Nafion see Mauritz and Moore. ... 

Fig. 1 Important ionomers (A) poly(ethylene-co-methacrylic acid), the free acid form of Surlyn, (B) Nafion, (C) SPS, and (D) poly(styrene-co-methacrylie acid). For the sake of simplicity, all polymers are shown in the acid form. In the ionomers, the acids are partly or fully neutralized with cations such as Na, NH4, or Zn. ...

As for ASAXS, we are currently using this technique to separate the crystallite and ionic "peak" scattering in the semicrystalline ionomers Nafion and Surlyn. Since these two scattering sources overlap in q-space, it has in the past proved difficult to separate and model these scattering sources, but with ASAXS this task becomes possible. Also, we are investigating the hlgh-q shoulder we have observed in the SAXS patterns of sulfonated polyurethane ionomers[45], which may be evidence of structural order within the ionic aggregates. 

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