Physical and thermal properties of binary and ternary blends of polypropylene, crumb rubber and wood flour
- Authors: Mosia, Lefika Ellen
- Date: 2020
- Subjects: Polypropylene , Polymers Materials science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49193 , vital:41609
- Description: The properties of binary and ternary blends of polypropylene (PP), crumb rubber (CR) and wood flour (WF), with and without ethylene-1-butene as a compatibiliser, were studied. The design of experiment (DoE) was used to determine the proportions of each component for various composites. The components were mixed using the Haake Thermo scientific Polylab QC internal mixer and the crumbs were then moulded into different shapes using the ARBURG 221-55-250 injection moulding machine. The properties of the blends were investigated using a scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanic analysis (DMA), tensile tester, water absorption and thickness swelling tests. The morphology of the blends showed the agglomeration of fillers (CR and WF) and more voids on untreated blends but on the treated blends fewer voids as well as improved distribution and dispersion were observed. PP bonded better with WF than with CR. The incorporation of both fillers improved the thermal stability, glass transition temperature, and melt temperature as well as crystallisation temperatures of the blends. Yet these fillers reduced the tensile strength and the yield strength of PP. The addition of WF increased the elongation at break and hardness of the blends but decreased the impact strength of the blends, whereas the addition of CR improved the elongation at break and impact strength of the blends and decreased the hardness of the blends. The blends with more WF absorbed more water and swelled more than the blends containing a high amount of CR. The incorporation of compatibiliser further decreased the tensile strength but improved the thermal stability and elongation at break of the blends. The water absorption and swelling of the blends seemed to decrease with the addition of the compatibiliser whereas the hardness increased. The impact strength of the blends containing more WF, increased after the addition of compatibiliser. The ternary blends showed better results than the binary blends.
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- Date Issued: 2020
The use and performance of recycling polypropylene in lead-acid battery cases
- Authors: Rust, Nico
- Date: 2004
- Subjects: Polypropylene , Lead-acid batteries
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10978 , http://hdl.handle.net/10948/269 , Polypropylene , Lead-acid batteries
- Description: Polypropylene has proven to be the ideal material for the outer shell of the lead acid batteries. Due to its mold-ability and inert properties the material provides a capsule for the functioning components of the lead acid battery and can withstand a variety conditions encountered during its application, such as impact shock resistance, high and low temperatures and acid resistance. Polypropylene has however become of great concern with regards to environmental pollution since it is generally resistant to normal conditions of degradation and can only be properly disposed of by incineration. This factor has encouraged the industry to find ways to regenerate spent polypropylene. A good example of such a process is the recycling of lead acid batteries. This allows not only for the regeneration of lead, but also for the recycling of polypropylene in the manufacturing of battery cases. There are some cost advantages in using recycled polypropylene. However it does have its disadvantages in that the material does start to deteriorate after multiple processes. A common practice amongst battery manufacturers is to add virgin polypropylene to the recycled material in order to ensure performance consistency. The comparative study investigated the use of various ratios of virgin and recycled PP in the manufacturing of lead acid battery cases and their influence on the physical properties and performance of the final material. The degradation of PP was also investigated as the material was subjected to multiple manufacturing processes where the influence of stabilizers was further considered. A common technique of PP analysis such as MFI was shown to be an effective technique to maintain good quality control. The study further showed that it is important that the material grade of PP used in the manufacturing of the battery case and lid is compatible in order to allow for effective heating sealing of the two components. Polypropylene has a waxy surface finish and it is generally difficult to label or write on. Labels tend to fall off in application and make it difficult to maintain a track record of the manufactured batteries with time. This study showed successfully that a laser activated dye can be added to the PP without influencing its color or its performance. This allows for successful labeling of battery cases by various bar coding writers that can trace the battery through its manufacturing process. Lead acid batteries are often operated outside the specified temperature range that is determined by battery manufacturers resulting in premature failure. These failures can occur within the warranty period of the battery and result in illicit claims since the monitoring of the batteries in its application was not possible. A suitable temperature monitoring device was designed that would be incorporated into the vent cap or lid of the battery case. The device contained temperature sensitive indicators that would undergo a permanent color change at specified temperatures thereby giving the battery manufacturer an indication as to the maximum temperature the battery was exposed to.
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- Date Issued: 2004