Virgin natural rubber

Study of strain dependence of tanS shows that, for all compounds tan8 increases with increasing in strain. The trend of tanS can be divided in two zones i.e. elastic zone (tanS < 1) and viscose zone (tanS > 1). It is indicated that the elastic zone of reclaimed is longer than NR, and in NR/reclaimed rubber blends with increasing reclaimed rubber content elastic zone becomes longer. This is due to the fillers left in reclaimed rubber. Non-homogeneity of phases and non-uniformed dispersion of fillers in NR/reclaimed rubber 50/100 and 75/50 cause shorter elastic zones in these blends than virgin natural rubber [90]. 

FIGURE 38.7 Viscosity versus shear rate plots of virgin natural mbber-low-density polyethylene (NR-LDPE) blends (N2) and reclaimed rubber (RR)-LDPE blends (A2). (Reprinted from Nevatia, P., Baneijee, T.S., Dutta, B., Jha, A., Naskar, A.K., and Bhowmick, A.K., J. Appl. Polym. Sci., 83, 2035, 2002. With permission from Wiley InterScience.)... 

Natural rubber has long been an important commercial material, and a rubber plantation is almost as effective as a virgin forest in carbon dioxide absorption. ... 

Hot-Applied Rubberized Asphalt. Hot-applied rubberized asphalts consist of proprietary blends of asphalt, mineral fillers, elastomers (natural, synthetic, or a blend of both), virgin or reclaimed oil, and a thermoplastic resin. It is applied hot in such a manner as to form an impermeable monolithic membrane over the surface to be waterproofed, which may be concrete, gypsum board or wood. Improved versions of this type of system consist of two coats of rubberized asphalt with a polyester mat in between, ealled the fully reinforced or two-ply system. 

The nature of the failures indicated that they were the result of solvent stress cracking. This is a well-recognized phenomenon, although the exact mechanism for such failure is not fnlly understood. This type of failure has not been encountered in pipe made from virgin, specification grade ABS. The failures are a direct result of using reprocessed materials, contrary to the requirements of the ASTM specification. The factors that contributed to the low environmental stress crack resistance were the distribution of the acrylonitrile, the rubber particle size, and the lower molecular weight. 

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