Ionomer barrier properties

These blends are commercially available, e.g., Zytel 3100 , Grilon BT. They show improved processability, solvent resistance, elongation, low-temperature impact and tensile strength, as well as enhanced barrier properties (see Table 1.56). They have been also incorporated into more complex, multicomponent systems, e.g., PA/PARA = 1 1, PPE, PCL, ionomer, EPR, a monomeric mixture of oxide and/or carbonate [e.g., ethylene carbonate, ethylene oxide, etc.] and a polyhydric alcohol [e.g., ethylene glycol, or trimethylene glycol]. The alloys were used to mold parts for the automotive, electrical or electronic industries [Hamada et al., 1994],... 

Blends with LLDPE were compatibilized by ethylene ionomers, which complexed with PVOH at the interface, giving good tensile and barrier properties [190]. 

As previously reported for Nafion, the membrane thickness has been reduced in order to decrease the ohmic drops within the membrane and to enhance the fuel cell performance. However, it requires a low gas permeation [ 141 ]. The gas barrier properties of Nafion are very good in the dry state [174], but they decrease when hydrated due to a higher gas solubility in the water phase than in the perfluorinated one. The gas permeation properties of SPIs have been determined as a function of the ion and water content [33,151,155,175,176]. While large differences in diffusivity and selectivity are observed in the dry state depending on the ion content [155], the gas permeation is significantly reduced when hydrated, which suggests the existence of a closed nanoporosity [151]. This porosity located in the ionic domains is then filled by water molecules, thus reducing the gas permeation. While the gas barrier properties of SPI can be considered as favorable for its use as a fuel cell membrane, they become a serious drawback for the use of this ionomer to prepare fuel cell electrodes (see Sect. 4) [177]. 

While the gas barrier properties of sPI ean be eonsidered as favorable for its use as a fuel eell membrane, they beeome a serious drawback for the use of this ionomer to prepare fuel ceU electrodes [131]. 

Ethylene ionomers, such as Surlyn from DuPont , have been the premium sealant materials for packaging applications due to their excellent seal strength and process robustness. The ethylene ionomers achieve the unique property characteristics through the development of a network morphology. In this paper the development of new ethylene ionomers will be discussed. The versatile compositions and the unique morphology of the new ionomers will be presented together with the novel gas permeability properties. Their enhanced breathability to oxygen, carbon dioxide, moisture, etc., selective permeability, and smart barrier properties will be presented. 

Conventional ionomers are widely used as sealant in the packaging industry because of their excellent seal strength and hot tack over a wide sealing temperature range, combined with good mechanical properties and moderate gas barrier property. 

FAMI compositions with potassium as the counter-ion have demonstrated significantly enhanced water vapor permeability (Figure 4) [25]. When compared with LDPE and a conventional ionomer FAMI-K s exhibited greatly enhanced water vapor permeability. It s worth noting that an FAMI with magnesium as the counter-ion exhibits comparable moisture barrier property to that of LDPE and conventional ionomer. The unique property of high moisture permeability, as shown in Figure 4, is enabled only by FAMI-K. This is attributed to the favorable interactions between the hydrophilic potassium carboxylate and the water molecules. 

High barrier polymers, such as polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), polyester, acid copolymers and ionomers have been proposed and are under evaluation as a replacement for PE. However, they present some drawbacks in terms of scalability and/or mechanical properties and/or outgassing rates. Cost of these polymers is also generally higher. 

Tie layers are used to adhere incompatible layers of dissimilar polymers. EVA, EMA, EAA, EEA, EnBA, SB, and ionomer are frequently used copolymers. The importance of tie layers for coextrusion has led material suppliers to develop new chemically modified polymers for specific applications. Tie layers also contribute physical properties, optics water barrier, modulus, thermal resistance. 

Xu XF, Ghanbari A, Leelapornpisit W, Heuzey MC, Carreau P. Effect of ionomer on barrier and mechanical properties of... 

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