The characterization of and formulation development using a novel tyre devulcanizate
- Authors: von Berg, Stuart , Hlangothi, Percy
- Date: 2016
- Subjects: Rubber, Reclaimed Rubber chemicals Tires -- Recycling
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/13149 , vital:27156
- Description: 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.
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- Date Issued: 2016
An analysis of development strategies aimed at meeting employment equity objectives within Medscheme
- Authors: Groenewald, Annaline
- Date: 2006
- Subjects: Medscheme (Firm) , Affirmative action programs -- South Africa , Employees -- Training of -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8554 , http://hdl.handle.net/10948/515 , Medscheme (Firm) , Affirmative action programs -- South Africa , Employees -- Training of -- South Africa
- Description: South Africa has undergone major social and political changes over the past two decades. In addition, new legislation in the form of the Employment Equity Act (No. 55 of 1998), which regulates employment practices in an attempt to make the workplace a true reflection of the South African population, was introduced to employers. The implementation of this Act has a major impact on organisations in South Africa and definitely influences the way in which they do business. Organisations, large and small, in every sector are being squeezed in all dimensions. They compete for customers whose expectations of quality, price and service are constantly increasing. Throughout the world, education, training and equitable working practices are recognised as essential ingredients to compete successfully and to ensure high performance practices. This research paper investigates whether the employee development strategies at Medscheme (the organisation selected for this study) are aimed at meeting employment equity objectives. An important reason for the investigation is that globalisation and the need for organisations to gain sustainable competitive advantage require new and different approaches for the recruitment, training, development and retention of employees with key skills. The key to success will, however, be for organisations in South Africa to find a middle way between ensuring equity, while remaining competitive. In order to achieve the objective of the research, the following approach was followed: Firstly, a comprehensive literature study was conducted to determine the legislative basis for equity and employee development; Secondly, a survey of literature dealing specifically with employee development initiatives available to organisations was conducted; Thirdly, the views of the employees within Medscheme were obtained to determine to what extent the organisation implemented the Employment Equity Act and what development strategies are used to facilitate the Abstract iv development of individuals from the previously disadvantaged designated groups to equip them for future positions in senior and top management; and, Lastly, the responses to the questionnaire were analysed to determine the extent to which Medscheme’s employee development strategies support the objectives of the Employment Equity Act.
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- Date Issued: 2006