Bound rubber content from

Bound Rubber Content from Toluene Extraction Kinetic Method... 

Another attempt by Tricas et al. to modify the surface of carbon black was by the plasma polymerization of acrylic acid [34]. Treatment with acrylic acid made carbon black hydrophilic. Plasma-coated carbon black was mixed with natural rubber and showed increased filler-filler interaction. The bound rubber content was reduced after the surface treatment of the filler. The authors also concluded that the surface of the carbon black was completely covered by the plasma polymer film, preventing the carbon black surface from playing any role in the polymer matrix. 

Since we are dealing with a niunber of different effects superimposed on each other, according to Kraus, it is natural to observe a lack of correlation between the bound rubber content and reinforcement. The nature of polymer-filler bonds and their role in the reinforcement of elastomers was considered by Rehner. On the basis of analysis of the deformation properties, it was estab-hshed that the strength of bonds present in vulcanizates is characterized by a very broad spectnim of forces. From the data on the swelling of filled systems, it is possible to determine the concentration of physical bonds (or attachments) of macromolecides to the surface, which restrict the degree of swelhng and the niunber of chemical crosshnks. 

The first is an EPDM fraction which is loosely bound to the carbon black due to adsorption interactions. This loosely bound rubber has numerous adsorption network junctions, similar to those in bound rubber. The second EPDM fraction, consisting of extractable rubber, contains a relatively small number of adsorption network junctions and can apparently be extracted from the compounds. The fraction of loosely bound EPDM chains determined with the aid of NMR increases with an increase in the maximum possible EPDM-carbon black contact area per unit volume of the elastomer, regardless the type of carbon black used, and is relatively close to the content of bound rubber [62]. 

According to a JSR patent Nd-catalysis allows for the polymerization of BD in the presence of carbon black. By this method a BR/carbon black master batch is obtained. The master batch technology eliminates time and energy consuming mixing of carbon black and rubber [340,341]. According to this patent the content of bound rubber (amount of rubber which can be extracted from a carbon black/rubber mixture with an appropriate solvent, e.g. toluene) is increased and vulcanizate properties are improved. 

Figure 15.34. Bound rubber vs. oxygen content in carbon black determined for NBR compositions. [Data from Bandyopadhyay S, De P P, Tripathy D K, De S K, J. Appl. Polym. Sci., 58, No.4, 1995, 719-27.]...

Acrylonitrile - butadiene rubber Europrene N3325 (bound ACN content 33%) was supplied by Polimeri Europa (Italy). Precipitated silica Ultrasil VN3 was obtained from Evonik Industries (Germany). Vinyltrimethoxysi-lane U-611 was obtained from Unisil (Poland). Rhombic sulfur was... 

No Amount of the bound ozone relative to the rubber, mass % Solid resi- due, mass %. pH value after ozonization Surface tension, mN/m Content of carbonyl groups in rubber, mass % Content of carboxyl groups in rubber, mass % Solubility of rubber in toluene, mass % Gel content, mass % Averaged-viscous molecular mass (MM) of rubbers released from rubber samples... 

Figure 15.34. Bound rubber vs. oxygen content in carbon black determined for NBR compositions. [Data from...

Ghosh et al. (32) had developed a new vulcanization technique to mitigate the cure-rate mismatch of NR/EPDM blends by introducing a multifunctional additive, namely, DIPDIS. In order to control the curative diffusion from the nonpolar to polar elastomer, EPDM has made more polar through its reaction with DIPDIS. Although EPDM used in the investigation has a low unsaturation content (5%), it will react with DIPDIS and yield rubber-bound intermediates as shown in Fig. 15.2 (32). It was... 

Reasonably early however in the development of telechelic polybutadiene/acrylonitrile, Brenner and Drake (22) showed that mercaptan- and carboxyl-terminated liquid polybutadiene/acrylonitrile did respond to electron-beam (1-5 megarads) and cure (2-3 seconds/pass) from the liquid to the solid state. The mercaptan polymer (3.1% RSH, 23% bound acrylonitrile, Mn 1700) cured more readily. CTBN as expected required 50-100% higher irradiation dosage levels. With both MTBN and CTBN-type products of higher acid content (6% vs 3%), gum rubber properties of 13.8-34.5 mPa were obtained with 60-100% elongation. The E-beam cures were carried out in air at ambient temperature. Thus, unformulated telechelic polybutadienes were shown to be substantive to cure in the presence of ionizing radiation. 

SBR/PVC blends with nitrile rubber (NBR) as a compatibilizer show improved mechanical properties at lower cost than NBR/PVC. i This was the conclusion of studies using a divinylbenzene cross-linked, hot-polymerized emulsion polymer with 30% bound styrene and a cold-polymerized emulsion polymer with 23% boimd styrene PVC with inherent viscosity from 0.86 to 1.4 NBR with Mooney viscosity from 30 to 86 acrylonitrile content of 23.5, 32.6, and 39.7% and ZnO, stabilizers, sulfur, and accelerators. ... 

It was found that the value of mean molecular weight of original Indian rubber present in the fraction soluble in toluene was equal approximately to 1,188,000 units. Ozonization of the Indian rubber in latex with the attachment of 0.8-1.0 mass % of ozone reduced mean molecular weight up to 990,000-993,000 units, that is, to the value that approximately corresponded to the working viscosity of mechanically plasticized mbber with Mooney viscosity equal to 50-55 units. Dependence of the change of molecular mass for the ozonizated mbber on the amount of the bound ozone is presented in Table 13.1. In all of the samples of modified polymers extracted from the ozonizated Indian mbber latex content of the carbonyl and carboxyl functional groups regularly increased with an increase of... 

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