Rubber process analyser

Measurement of Dynamic Mechanical Characteristics Using Rubber Process Analyser... 

Rheological studies must be carried out to obtain information about the optimal time to vulcanization process, adjusting the vulcanization system to get the best mechanical properties or thermal properties and to estimate the cure rate index of the vulcanization process. Equipments like the rubber process analyser (RPA), a dynamic mechanical rheological tester, is a common equipment in the rubber industry. 

Results are presented of high strain testing for the characterisation and quality assurance of NR using the RPA 2000 rubber process analyser. Such testing was found to be more effective in detecting processability ditferences than traditional processing tests such as Mooney viscosity or Wallace plasticity. 24 refs. 

Physical tests that directly measure the viscosity of a rubber compound can also be useful. A good example of such a test is the one that can be conducted using a rubber process analyser to determine the modulus of a rubber compound. As the crosslinks are removed from a rubber the modulus will be reduced accordingly. If standards are prepared by vulcanising samples to various degrees... 

Workers in Brazil [31] have investigated the properties of revulcanised SBR that has been recovered from scrap rubber. Their work involved compounding the recovered SBR with an aromatic oil and different conventional ruhher cure systems. The curing behaviour of these compounds was then evaluated using a rubber process analyser. 

FD-MS is also an effective analytical method for direct analysis of many rubber and plastic additives. Lattimer and Welch [113,114] showed that FD-MS gives excellent molecular ion spectra for a variety of polymer additives, including rubber accelerators (dithiocar-bamates, guanidines, benzothiazyl, and thiuram derivatives), antioxidants (hindered phenols, aromatic amines), p-phcnylenediamine-based antiozonants, processing oils and phthalate plasticisers. Alkylphenol ethoxylate surfactants have been characterised by FD-MS [115]. Jack-son et al. [116] analysed some plastic additives (hindered phenol AOs and benzotriazole UVA) by FD-MS. Reaction products of a p-phenylenediaminc antiozonant and d.v-9-lricoscnc (a model olefin) were assessed by FD-MS [117],... 

Dynamic mechanical analysers, as discussed in chapter 9, can be constructed so that they can be used with unvulcanised materials and, hence, the in phase and out of phase components of modulus and the loss angle measured. The usual test piece geometries for cured rubbers are not convenient for the uncured materials where some form of oscillating shear is probably the best approach. This is the geometry used in cure meters discussed in the next section and such instruments have formed the basis for apparatus which measures dynamic properties from before and through the curing process. 

In the plastic flow process, large displacements of the whole chain are performed to reach the involved strain values. Such displacements are analogous to those that happen during polymer flow above the glass-rubber transition (a transition) temperature. These motions are performed by segmental backbone conformation changes with intra- and intermolecular cooperativity specific of the a transition. They will be called a transition motions, in order distinguish them from the /3 transition motions analysed in [ 1],... 

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