Guayule Natural Rubber Based on Zero Waste Tehnology-the Indian Perspective

The present trend in the rubber industry is to look for additional sources of natural rubber. Now Guayule Natural Rubber (GNR) stands first in this endeavor, since its discovery nearly 500 years back. There were a number of ups and downs in its production and utilization in the last one and half century. Recently a workshop was organized at IIT Kharagpur (India) and the members deliberated different prospects of GNR. It was stressed that Guayule shrub is an important industrial crop for the production of natural rubber, apart from Hevea Natural Rubber (HNR) because of increasing gap between demand and supply and fluctuating price of the HNR in the world market.

The latex derived from Guayule shrub is devoid of allergenic protein hence most suitable for biomedical applications. The resin derived from the shrub has antibacterial and antifungal properties suitable for antitermite paints and so on. The biomass residue after the extraction is suitable for bio-fuel and bio-energy production making the whole process biodegradable, thus converging the technology to a zero waste technology. The concept is novel and work is in progress in India to make it successful in the semi-arid and arid regions of the country. 

This paper will highlight the specific characteristics of GNR in comparison with HNR. Chemical modification of the GNR has been carried out to improve the processing and technical properties of GNR. The PCP-g-GNR was characterized by U.V.; FT-IR and ¹HNMR spectroscopy. Phosphoylated cardanol (PCP) was used to modify GNR and optimization was done by using Taguchi methodology. It was concluded that 5 percent of PCP and 2 percent of the initiator reacted with GNR latex for 10 hrs at 40⁰C to achieve a grafting percentage of 4.6% and a grafting efficiency of 92.6. The number average molecular weight and polydispersity index significantly increased after grafting of PCP on to GNR backbone. Thermal analysis reveals that PCP-g-GNR exhibits a lower glass transition temperature than raw GNR but it experiences higher thermal stability.