Vulcanisates, additives Carbon-blacks

Okumoto [89] has reported an analytical scheme (Scheme 2.8) for automotive rubber products (ENB-EPDM vulcanisates). For high-resolution PyGC analysis, organic additives are first removed from the rubber/(CB, inorganics) formulation. Carbon-black and inorganic material hardly interfere with pyrolysis. For the analysis of the additives the extracted soluble... 

Table 6.40 Optimal methods for detection of organic additives in carbon-black-filled rubber vulcanisates...

The incorporation of carbon black into elastomeric systems is a process of significant commercial importance. However, the additional stiffness of the sample imparted by the reinforcement effect of fillers is not favourable in terms of the experimental conditions for high-resolution NMR spectroscopy. Electric conductivity of the carbon black may also interfere to some extent. Under these circumstances, filled formulations are not widely used for the study of elastomer vulcanisations where high resolution and signal-to-noise ratios are required to detect small amounts of vulcanisation products. 

Carbon black filled NR vulcanisates have been studied by high-resolution solid-state 13C NMR at 75.5 MHz. It is shown that the detection of poly- and mono-sulfidic crosslinks with 13C MAS spectroscopy is also possible in the case of carbon black filled NR vulcanisates. Quantitative results suggest that the addition of carbon black leads to a decrease in crosslink density with increasing filler content [55]. 

All the values measured of this sample and the necessary reference values are collected in Table 10.4 The two separate Tg-values at -99°C and at -64°C confirm that the vulcanised rubber sample consists for 52 %wt. of a BR/NR blend (the Tg-value of the BR phase might be shifted to higher temperatures due to the oil addition the Tg-value of the NR phase is hardly influenced by the oil addition). The sample also contains 15 %wt. of oil and 32 %wt. of carbon black. About 25 milligramme of sample and about 16 instrument hours were necessary for this analysis. 

Another study by Sui et al. shows the vulcanization curves of the neat NR and NR composites. In Figure 21.11 it can be seen that the scorch time (measurement of premature vulcanization) decreased after adding CNTs or carbon black into the NR. This may be because when CNTs are added, they would absorb the basic accelerator species and delay the onset of vulcanisation. The reason for this is that the addition of the CNTs could improve thermal... 

Vulcanisation of conductive silicone rubber compositions is, like conventional silicone rubber, by peroxide. However inhibition of dichlorobenzoyl peroxide by carbon blacks makes it necessary to use an alternative curing technique, i.e. hydrosilylation or addition curing, for hot-air vulcanisation. Applications for conductive or antistatic silicone rubber include ... 

The nature of the vulcanisation of trans-1,4-polyisoprene (TPI) and the effect of the degree of vulcanisation on the mechanical properties of vulcanised TPI were studied. The results showed that among three conventional types of accelerator used, (M, CZ, and TT), the vulcanisation curve of TPI with CZ as accelerator was found to be the most suitable. Vulcanised TPI was found to change suddenly from a hard material to a soft elastic rubber when the sulphur content increased from 4 phr to 5 phr. In addition, the addition of carbon black influenced the tensile strength advantageously. 5 refs. 

The charged vulcanised elastomers show a higher hysteresis that the non-charged vulcanised rubbers. The introduction of black carbon particles in rubber determines the increase both of hydrodynamic and viscoelastic hystereses. The two contributions are additive. Under the conditions of the deformation rate and temperature variation, the first one remains constant, but the second one decays with the decrease of temperature. The viscoelastic contribution was ascribed to the macromolecular chains, immobilised on the black carbon surface, which modify the viscoelastic response of the elastomer network. 

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