The amount of waste tyres being dumped is fast becoming a problem. These stockpiles take up valuable land and are an environmental and health problem. While incineration is the simplest way to recycle the used tyres it isn’t an efficient way to dispose of tyres. This research looks at developing a method for characterizing the New Reclamation Group (NRG) reclaim with the main focus on Hi-Res™ thermogravimetric analysis. Good quantification was possible using this technique. A trade off was established between resolution, sensitivity and time. While increasing the resolution allowed greater separation to be achieved the time for each experiment increased rapidly. Although kinetic models do exist for quantifying rubber components in vulcanized sample, they were not suitable for this study. When devulcanization causes significant molecular changes, such as with NRG reclaim, the decomposition profiles no longer match those of virgin materials. Formulations developed focused on mixing, rheometry, crosslink density and tensile properties. The NRG reclaim acted as a processing aid which lowered the maximum torque. This provides mixing safety as the temperature is decreased as a result of the lower torque. This effect was not seen with conventional reclaim. Rheometry tests indicated that the addition of the devulcanizates decreased the extent of cure. It was demonstrated that this could be linked to crosslink density. Testing of the 100%, 200%, 300% moduli correlated the crosslink density to the maximum torque. Although the addition of NRG reclaim reduced the tensile strength of the formulation, a link between crosslink density and ultimate tensile strength (UTS) couldn’t be made. The decrease in the UTS and increase in extension at break is possibly caused by an increase in low molecular weight material present in the formulations and decrease in crosslink density. This could possibly increase the mobility of polymer chains which could increases flexibility.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Quality Management, Durban University of Technology, 2014. / Hearing conservation in the industrial setting has mainly focussed on the harmful effects of noise exposure on the auditory system. This study investigated the co-exposure to noise and ototoxic chemicals on the auditory system of workers engaged by labour brokers. It examined the adequacy of current occupational health and safety legislation to address chemically induced hearing loss and makes recommendations at a policy level to protect workers’ hearing at the workplace. This study is an exploratory cross-sectional field case study in an industrial setting. A sample of 300 workers was drawn from a rubber factory involved in the manufacture of components for the motor, shoe and plumbing industries in the metropolitan area of Durban. Purposive sampling was undertaken amongst a cohort of day shift workers which constituted the research subjects. The research tools used in the study included the completion of the NoiseChem questionnaire, conducting pure tone audiometric testing on research subjects, monitoring noise exposure levels and performing chemical air monitoring of the ambient environment. This study confirms that a segment of the research subjects were exposed to both ototoxic chemicals and noise. Chemical exposure of research subjects was within legal permissible limits in most instances. Noise exposure exceeded the noise rating limit of 85 dBA in certain work areas. Multiple regression analysis revealed that there was a slight trend towards co-exposure to chemicals and noise being risk factors for hearing loss with an odds ratio of 1.7 (95% CI = 0.34 – 8.57) but the p value was not significant. No significant association with hearing loss was evident for workers exposed to chemical only with odds ratio of 0.41 (95% CI = 0.11 – 1.53, p = 0.19) and noise only with odds ratio of 0.87 (95% CI = 0.32 – 2.31, p = 0.78). The study indicated that workers exposed to both ototoxic chemicals and noise may be more susceptible to hearing loss in their current jobs. The study draws attention to policy gaps in the Occupational Health and Safety Act and proposes changes to address the shortcomings. / D