Natural rubber and polybutadiene

Natural rubber and polybutadiene each contains just one monomer, but the versatility of mbber materials is greatly Increased by pol3Tnerizing mixtures of two different monomers to give copolymers. Because of their diverse properties, copolymers account for over 60% of the 2.1 X 10 kg of rabber produced in the United States each... 

Studies performed on elastomers have shown that the cross-linking efficiency is relatively low. G(X) values of 1 and approximately 3 were found for natural rubber and polybutadiene, respectively, when irradiated at... 

The crosslinking of natural rubber and polybutadiene has been extensively studied. The mechanism of radiolysis of these polymers, however, is not yet fully understood. Many discrepancies, in fact, exist between the reported results. These are most certainly due to the impurities present in the samples. A summary of the reported data has been given by Schultz [323] and by Chapiro [285]. For purified natural... 

Although It Is not possible to differentiate the mechanism responsible for the trans structure, earlier researchers (23) believed path B to be very minor. Table I lists the normally observed, solid state NMR, carbon resonances for natural rubber and polybutadiene... 

Polymer blends, in which the constituent polymers are incompatible, tend to improve fatigue resistance. For example, natural rubber and polybutadiene show good resistance to fatigue, crack initiation, and growth because of the formation of heterogeneous polymer phases a crack growth in one polymer phase is arrested at the boundary with the adjacent polymer phase. 

Natural rubber and polybutadiene blends tend to be used in tire sidewalls, which undergo flexing, and in tire treads, which have a lug pattern and contain high-stress zones at the base of the tread blocks. 

Discuss chlorination of natural rubber. How can natural rubber and polybutadiene be bromi-nated ... 

Compatible polymer blends Natural rubber and polybutadiene Polyamides (e.g., PA 6 and PA 66)... 

Where the solubility parameter rule is in error is for natural rubber and polybutadiene. The differential in solubility parameters is around 0.6 but the two polymers are immiscible. Polybutadiene grade IISRP 1207 and an oil extended polymer such as IISRP 1712 have a differential of less than 0.1 and in this case the two elastomers are nearly fully miscible between the lower and upper critical solution temperatures. The blended elastomers mechanical properties then become a function of the filler type, distribution, vulcanization system, and any processing aids present. 

The discovery of butyl rubber was, in fact, the discovery of the limited-functionality elastomers. Unlike natural rubber and polybutadiene, which have... 

Terpene resins will be effective as solid solvents for an elastomer when their Hildebrand solubility parameters are close to the Hildebrand solubility parameters of the respective polymer. For example, from Table 22.4 it can be seen that pure polyterpene resins are suitable tackifiers for poly(ethylene) (PE), natural rubber, and polybutadiene polymers. Further, terpene phenol resins are suitable tackifiers for poly(vinyl acetate), poly(methyl methacrylate), and poly(ethylene terephthalate). 

In the very beginning we must recognise the fact that there are two different definitions of rubber . One is based on the chemical make-up, such as natural rubber and polybutadiene. The other is based on its physical behaviour. Sometimes a statement is made, after a long time (gum) rubber flows . In this statement the rubber is chemical by definition. The physical description is after a long time the material is no longer a rubber because it flows . 

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