Surfaces thermoplastic elastomers

Zinc salt of maleated EPDM rubber in the presence of stearic acid and zinc stearate behaves as a thermoplastic elastomer, which can be reinforced by the incorporation of precipitated silica filler. It is believed that besides the dispersive type of forces operative in the interaction between the backbone chains and the filler particles, the ionic domains in the polymer interact strongly with the polar sites on the filler surface through formation of hydrogen bonded structures. 

Reducing infiltration. Traditional brute force approaches to weather stripping were redesigned to reduce infiltration with less material that contacted a larger surface area. New materials such as thermoplastic elastomers offered additional potential to control for infiltration. But perhaps the most important way to control infiltration is proper installation. 

Such soft-touch materials are usually TP Vs or thermoplastic elastomers (TPEs) which combine the moldability of thermoplastics in the melt state with elasticity, lower hardness, fracture resistance, and surface characteristics of elastomers. However, plastics and elastomers respond differently to mechanical stress. Hence, both rheological behavior and mechanical strength will to a large extent depend on the morphology of the blend which may change with change in the composition. 

The use of lightly crosslinked polymers did result in hydrophilic surfaces (contact angle 50°, c-PI, 0.2 M PhTD). However, the surfaces displayed severe cracking after 5 days. Although qualitatively they appeared to remain hydrophilic, reliable contact angle measurements on these surfaces were impossible. Also, the use of a styrene-butadiene-styrene triblock copolymer thermoplastic elastomer did not show improved permanence of the hydrophilicity over other polydienes treated with PhTD. The block copolymer film was cast from toluene, and transmission electron microscopy showed that the continuous phase was the polybutadiene portion of the copolymer. Both polystyrene and polybutadiene domains are present at the surface. This would probably limit the maximum hydrophilicity obtainable since the RTD reagents are not expected to modify the polystyrene domains. 

Semifluorinated block copolymers, (I), were previously prepared by the author [1] and then blended with styrene-ethylene/butylene-styrene thermoplastic elastomers to provide surface-active block copolymers. 

Some recent examples including uses as super hydrophobic surfaces [142], medical composites of spun fibers, generating scaffolds for cell attachment [138], thermoplastic elastomers [139], as a supramolecular electrolyte in a dye-sensitized solar cell [190], as a method to align polymer chains [191], or as supramolecular polymer composites [192] have been discussed previously. Still there is ample space to be explored and there definitely will be many more patents and applications in this field. 

There are a number of models for polarization of heterogeneous systems, many of which are reviewed by van Beek (23). Brown has derived an exact, though unwieldly, series solution using point probability functions (24). For comparison to spectra for the thermoplastic elastomers of interest here, the most useful model seems to be the one derived by Sillars (25) and, in a slightly different form, by Fricke (26). The model assumes a distribution of geometrically similar ellipsoids with major radii, r-p and rj which are randomly oriented and randomly distributed in a dissimilar matrix phase. Only non-specific interactions between neighboring ellipsoids are included in the model. This model includes no contribution from the polarization of mobile charge carriers trapped on the interfacial surfaces. 

Thermoplastic elastomers (TPE) Styrene-butadiene-styrene (SBS) and styrene-isoprene-styrene (SIS) block copolymers represent primary materials for other hotmelt adhesives. They are characterized by long open times, high elasticity levels, good spring qualities and a lasting stickiness, so that precoated surfaces always retain some of the qualities of PSAs. The melting temperatures of these adhesives are particularly low at about 65°C, so that they can be used for thermally sensitive materials (foams, fleeces, thin films). 

Adhesives and sealants, cast elastomers, microcdWar products, polyurethane stretch fibers (Spandex fibers i, surface coatings, thermoplastic elastomers and Billable gums—... 

Intense commercial and academic interest in block copolymers developed during the 1960s and continues today. These materials attract the attention of industry because of their potential for application as thermoplastic elastomers, tough plastics, compatibilizing agents for polymer blends, agents for surface and interface mo dification, polymer micelles, etc. Academic interest arises, primarily, from the use of these materials as model copolymer systems where effects of thermodynamic incompatibility of the two (or more) components on properties in bulk and solution can be probed. The synthesis, characterization, and properties of classical linear block copolymers (AB diblocks, ABA triblocks, and segmented (AB)n systems) have been well documented in a number of books and reviews [1-7] and will not be discussed herein except for the sake of comparison. 

Thermoplastic elastomers can be one of the components in multilayer extrusion. They can serve either to bond two dissimilar materials, for example, ABS and high Impact polystyrene, or as a layer with physical properties that contribute to the film properties, for example, a film with an S-EB-S center and a polypropylene outer surface. In this case they yield a flexible film with a nontacky surface. In other cases, multilayered films can be constructed to control gas permeability. 

More recently, blends of a partially crosslinked thermoplastic elastomer with 5-40 parts of a PO (viz. LLDPE, PP, EPR, or PB-1) were developed for low density, foamable alloys [Okada et al, 1998a]. The density was reduced at least by a factor of two. In the following patent 1-17 wt% of a long-chain branched PP was also added [Okada et al, 1998b]. The extmded foam was free of surface roughness caused by defoaming, was soft to the touch and showed excellent heat and weathering resistance. 

Thomas and co-workers [1986] studied effects of gamma-irradiation on a thermoplastic elastomer, TPE, a polyether-ester block copolymer from 1,4-butanediol, polybutylene glycol and terephthalic acid (Hytrel D40), TPE, and its blends with PVC, in air, at doses of 1, 10, 100 and 500 kGy. Visual inspection of the samples showed no color change up to 500 kGy, but the samples irradiated at 500 kGy showed surface cracks. 

The market of PP/EPDM blends has grown dramatically because of its recycling abihty and processability by conventional thermoplastic processing equipment. The unique characteristics of thermoplastic elastomer made it an attractive alternative to conventional elastomers in a variety of markets. Liu et al. showed from the experimental blends (53) that materials cost reduction of between 30% to 50% is possible in comparison to commercial products if one applies the PP/EPDM blends to the construction of a basketball court, a tennis court, and a roller hockey rink, which were estimated around 7000, 14,000, and 40,000, respectively. The cost comparison took into account the percentage of rubber or PP used in experimental blend, the exponential factor for a scale-up process and the overall surface area of the specific applications. Among many possible application of this blend two readily feasible applications are roofing and flooring. 

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