Vulcanized advantages

Many grades of recycled rubber produced from grinding and heating of vulcanized rubber products such as tyres, baby bottle nipples and other goods are also available. Although reclaimed rubber offers some processing advantages, its use has declined in recent years because of the extensive use of blended polymers. 

Thermoplastic elastomers are materials that have the properties of vulcanized rubbers but can be processed by techniques associated with thermoplastics. The commercial importance of TPEs is due to their superior processing properties and economic advantages over conventional rubbers and plastics. TPEs from rubber-plastic blends became important because they combine the superior processability of thermoplastics and the... 

There are a number of advantages, listed below, associated with the peroxide vulcanization of elastomers ... 

Solvent Resistance. One of the distinct advantages of a crystalline thermoplastic elastomer over an amorphous one should be its superior solvent resistance, since the latter types are generally soluble. Table III shows the swelling behavior of the H2-BIB triblocks in toluene at 25°C. It can be seen that the maximum swelling obtained was in the case of the H2-BIB-34, which had the lowest end-block content. Furthermore, the equilibrium swelling ratio of 3-26 obtained for this polymer is considerably less than the value of 5 or 6 generally exhibited by a well-vulcanized natural rubber. 

As with any scientific endeavor, chance discovery played an important role in the development of polymers. In all cases, however, there was a scientist with an open and innovative mind who was ready to recognize and take advantage of a chance observation. Charles Goodyear accidentally tipped sulfur into heated natural rubber to discover vulcanized rubber. Christian Schobein inadvertently wiped up a nitric acid spill with a cotton rag to discover nitrocellulose. Jaques Brandenberger thought of cellophane as he observed the accidental stains on tablecloths. Also, as was discussed in Chapter 1, Teflon was discovered upon the unexpected disappearance of a chemical in a gas cylinder that Roy Plunkett was compelled to saw in half. 

Thermoplastic tri-block copolymers are interesting since they possess novel properties different from those of the homo- or copolymers. The thermoplastic elastomers have many of the physical properties of rubbers, i.e., softness, resilience, and flexibility. The unique properties of this kind of copolymer are due to the microphase separation of the hard crystalline domains dispersed in a continuous amorphous matrix (Fig. 6). Such phase morphology provides a physical network of flexible chains cross-linked by crystalline microdomains. The advantages over natural vulcanized rubbers are that thermoplastic elastomers are readily soluble in an appropriate solvent and can be processed as thermoplastics [109],... 

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