NR Blends and IPNs

However, most NR blends and IPNs are heterogeneous due to the hydro-phobic nature of NR. They may form mixtures that are nanometres in size when mixed with the other polymers rather than interpenetrating each other on a molecular scale. They are expected to have total or partial phase separation. In other words, these systems may be in a continuously homogeneous phase only on a macroscopic scale. Thus, the number of glass transition temperature... 

The naturally biodegradable polymers such as starch, chitosan and cellulose derived from natural sources have produced a number of interesting NR blends and IPNs. These blended systems have an advantage in that they create fewer waste disposal problems compared to the petroleum based polymeric materials. The use of stareh blends to enhance the biodegradability of conventional plastics has been reported by many researchers in order to reduce the environmental impaet of petroleum based plastic products and waste. The NR/maize stareh blends exhibited a decrease in their mechanical strength due to the speeifie properties of starch. However, the blended polymers showed a low interfaeial interaetion between the two phases due to the different polarity behaviour of the hydrophobic NR and the hydrophilic starch. 

NMR spectroscopy is one of the most powerful techniques for the structural and physicochemical study of organic compounds, both small molecules and polymers. It seems to be highly suitable for studying NR-based blends and IPNs. Different NMR techniques have been used to study NR-based blends and IPNs, including NMR, and H NMR liquid state. However, only solid-state NMR can be used to study cured rubber, as this technique does not require the solubilization of the polymer. 

Reports in the literature on the transport of penetrant molecules through NR based blends and IPN s are few when compared to the existing literature on most common/commercial polymers/blends. The sorption and diffusion of aromatic penetrants into different NR blends such as NR/BIIR, NR/CIIR, NR/neoprene, NR/EPDM, NR/polybutadiene, and NR/SBR were studied by Siddaramaiah et al. The diffusion coefficient (D) of the penetrants was found to range from 6.8 to 84.3 x 10 cm /s at a temperature range of 25-60 °C. Results indicated that the transport data were affected by the nature of the interacting solvent molecule rather their sizes, and also by the structural variations of the elastomers blended with NR. The activation parameters for the diffusion of the penetrants ranged from 4.16 to 30.48 kJ/mol. 

LCA, Ageing and Degradation Behaviour of NR Based Blends and IPNs... 

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