Tensile properties, elastomeric

Jha A. and Bhowmick A.K., Thermoplastic elastomeric blends of poly(ethyleneterephthalate) and carylate rubber 1. Influence of interaction on thermal, dynamic mechanical and tensile properties. Polymer, 38, 4337, 1997. 

The ionomer which was isolated from the neutralization of sample SBD-2 was a brown-colored elastic network of moderate strength. Ionomer samples SBD-1 and SBD-2, neutralized to the stoichiometric end point using KOH, were compression molded at 140°C and examined for tensile properties. The results, as shown in Figure 16, illustrate the profound influence of crystallinity on the elastomeric inner block. The semi-crystalline material (SBD-1) behaves much like a rigid plastic, while the amorphous sample (SBD-2) is an elastomer of moderate strength. 

Elongation to failure measured in tensile stress-strain measurements at room temperature (i.e., approximately 25 C) vary significantly as the composition of the polymer is varied from the glassy PS to the elastomeric PB (Figure 6). Also it is clear that the tensile properties of the random copolymer is significantly different from the same composition block copolymer. This difference is due, in part, to the differences in molecular weight (Table 1). 

In the early 1950 s, B.F. Goodrich introduced the first commercial elastomer based on ionic interactions, a poly(butadiene-co-acry-lon1trile-co-acrylic acid). Typically less than 6% of carboxylic monomer 1s employed in order to preserve the elastomeric properties inherent in these systems. When neutralized to the zinc salt, these elastomers display enhanced tensile properties and improved adhesion compared to conventional copolymers. This enhancement of properties can be directly attributed to ionic associations between the metal carboxylate groups. 

The plots clearly indicate the elastomeric behavior of the star copolymers. The films of all three materials exhibited similar high elongation at break, about 500%, independent of the copolymer composition. As expected, the increase of the PMMA content in the copolymers resulted in an increase of the E modulus of the films from 1.02 to 4.76 and 11.18 MPa for samples with 13%, 26% and 36% PMMA respectively, suggesting a simple approach for tuning the tensile properties by adjusting the copolymers composition. 

The discovery of living cationic polymerization has provided methods and technology for the synthesis of useful block copolymers, especially those based on elastomeric polyisobutylene (Kennedy and Puskas, 2004). It is noteworthy that isobutylene can only be polymerized by a cationic mechanism. One of the most useful thermoplastic elastomers prepared by cationic polymerization is the polystyrene-f -polyisobutylene-(>-polystyrene (SIBS) triblock copolymer. This polymer imbibed with anti-inflammatory dmgs was one of the first polymers used to coat metal stents as a treatment for blocked arteries (Sipos et al., 2005). The SIBS polymers possess an oxidatively stable, elastomeric polyisobutylene center block and exhibit the critical enabling properties for this application including processing, vascular compatibility, and biostability (Faust, 2012). As illustrated below, SIBS polymers can be prepared by sequential monomer addition using a difunctional initiator with titanium tetrachloride in a mixed solvent (methylene chloride/methylcyclohexane) at low temperature (-70 to -90°C) in the presence of a proton trap (2,6-dt-f-butylpyridine). To prevent formation of coupled products formed by intermolecular alkylation, the polymerization is terminated prior to complete consumption of styrene. These SIBS polymers exhibit tensile properties essentially the same as those of... 

Wool, hair and other animal fibres have a hierarchical microstruclure and no reliable model has been developed for prediction of the failure stress of lhe.se fibres which encompasses all the relevant length scales. Three models are available to explain the tensile properties of a-keratin fibres all deal with a system of parallel microfibrils embedded in a proteinaceous matrix at a scale of 10 nm. In 1959, Feughelman laid the foundations of stmctural interpretation of the stress-strain curve with his two-phase model of microfibrils imbedded in a matrix, a model that was improved in 1994 (Feughelman, 1994). In the same year, Wortmann and Zahn (1994) proposed another version of the microfibril model. The third model, the Chapman and Hearle model (Hearle, 1967 Chapman, 1969) is based on the mechanics of stress transfer in a composite system consisting of microfibrils, which undergo an a p transition, in parallel with an elastomeric amorphous matrix. The Wortmann and Zahn model does not explicitly mention breakage of fibres, but it is implicit that this must be triggered... 

Journal of Applied Polymer Science 80, No.13, 24th June 2001, p.2545-57 TENSILE PROPERTIES OF ELASTOMERIC POLYOLEFIN THIN FILMS THE PATH TO FAILURE... 

Table 7.4. Tensile Properties of Castor Oil/Polystyrene SINs at Ambient Conditions Elastomeric Compositions ...

Testing of the tensile properties of the block copolymers showed good elastomeric behavior. For example, the triblock copolymer displayed an elongation to break of 1530%, the highest of the three samples. 

In conclusion, viologen elastomers derived from the reaction of telechelic liquid rubber with viologen moiety have high tensile properties and thermoplastic elastomeric properties. Further exj)crime 11 ts on functionalizations of NBV are being carried out. 

The stress-strain curve of an elastomeric CEPC copolymer (prepared by hydrogenating an SIS) is also illustrated. This copolymer shows a tensile modulus that is intermediate between the 40% and 60% 1,2 EB-containing copolymers, with ultimate tensile properties that are very similar to the 40 % EB samples. 

The nominal tensile strength //Aq is the maximum tensile stress which a material is capable of sustaining. The maximum extensibility is the corresponding rupture strain A,. These ultimate tensile properties of elastomeric networks are very sensitive to temperature and test conditions, but can be characterized by a failure envelope which is generally represented by a plot of log(/ro/AoT) vs. log(A, — 1) where Tand To are respectively the test temperature and a reference temperature. ... 

Other elastomeric-type fibers iaclude the biconstituents, which usually combine a polyamide or polyester with a segmented polyurethane-based fiber. These two constituents ate melt-extmded simultaneously through the same spinneret hole and may be arranged either side by side or ia an eccentric sheath—cote configuration. As these fibers ate drawn, a differential shrinkage of the two components develops to produce a hehcal fiber configuration with elastic properties. An appHed tensile force pulls out the helix and is resisted by the elastomeric component. Kanebo Ltd. has iatroduced a nylon—spandex sheath—cote biconstituent fiber for hosiery with the trade name Sidetia (6). 

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