The Development of a Recycled Plastic Wheel for Cardboard Collector Trollies - Improving the working conditions of informal cardboard recyclers in Durban, South Africa

Abstract

A large proportion of the global working population has jobs with poor working conditions and in- adequate governmental support. A typical example of such occupations are waste pickers, who earn their living by collecting and reselling recyclable waste material. Specifically, this thesis focuses on cardboard recyclers in Durban, South Africa, and the NGO AeT, who works with these recyclers and tries to improve their working conditions and livelihood. Therefore, the NGO has designed a special trolley, which should make it easier for the recyclers to collect cardboard and give them the possibility to earn a better living. Unfortunately, this trolley shows shortcomings in terms of the wheel design. Therefore, this thesis aims at improving the current wheel design of the trolleys in place to both, support the NGO efforts and the working conditions of the informal workers. To begin with, this thesis analyses the problems of the current wheel design and thus identifies a short durability and a difficult manoeuvrability. Supported by a scoping study on existing knowledge in the context of plastic recycled wheels, this study then develops various design alternatives under the restriction of certain criteria which include the possibility to be manufactured locally, keeping the costs as low as possible and using recyclable plastic. In the development process it became apparent that especially the flexibility of the tire is an important feature with regard to the bad road conditions in the city of Durban. The most promising way to increase the flexibility and still preserve the stability of the tire turned out to be via a stable tire design and the use of a more flexible material. The difficulty showed to be finding a material with increased flexibility that can both, be recycled and is available for manufacturing in Durban. Rubber, which is used for example in car tires, has very good properties and flexibility for the application, but can unfortunately not be remelted and thus not recycled in the classical meaning. Due to recent studies, this work proposes to use a material combination of recyclable plastic with old car tire rubber. The rubber is thereby not reused in the classical sense by melting, rather it is ground into powder and mixed with a recyclable plastic. A blend of 60-65% ground tire rubber with polypropylene was found to be the most suitable material combination. However, this choice could not be validated within the scope of this work and requires further research and testing. Still, this thesis was eventually able to make an important scientific contribution that sets the ground for improving the durability and manoeuvrability of cardboard collector trolleys by identifying a new promising and recyclable material.