Unsaturated oils, polymer blends

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

CPE is an ignition-resistant PE. It is also used in blends to change the ignition characteristics of other polymers. CPE has no unsaturation in the polymer backbone, giving it excellent ozone and weathering properties. The saturated backbone also results in a temperature stability that allows CPE to perform well continuously at temperatures of 150 °C. CPE can provide satisfactory resistance to most acids, bases, oils and alcohols. 

FIGURE 10.8 Probable crosslinking reaction between the three component bioblends described by Das et al. (2011). From Das, K Ray, D., Banerjee, C Bandyopadhyay, N.R., Mohanty, A.K., Misra, M., 2011. Novel materials from unsaturated polyester resin/styrene/tung oil blends with high impact strengths and enhanced mechanical properties. J. Appl. Polym. Sci. 119, 2174-2182, reproduced with permission of John Wiley and Sons, Inc. 

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