Dissertation: S.K. Ramamoorthy, Polymertechnology
2015-06-12, 10:00 — 12:00
Welcome to Sunil Kumar Ramamoorthy´s defence of his thesis "Properties and Performance of Regenerated Cellulose Thermoset BioComposites".
Oponent: Prof. Jyrki Vuorinen, Tampere University of Technology, Finland
Supervisor: Prof. Mikael Skrifvars
Biocomposites have been developed to address the sustainability issues of non-renewable resource based materials. These composites are often produced by reinforcing natural fibers in petroleum based thermoset resins or thermoplastic biopolymers. Thermoplastic polymers from renewable resources are commercially available whereas thermoset resins are predominantly derived from petroleum resources. Cellulose fibers have significant importance and potential for polymer reinforcement in lightweight composites. Natural fibers are chemically impure and their properties vary largely which makes it difficult for it to be used in several applications. The natural fiber based products are limited by their characteristic odour emissions. These issues of natural fibers can be addressed by partly man-made fibers i.e. regenerated cellulose which with little or no compromise in the environmental benefits of the natural fibers can be produced from biomass origin. Natural fibers and their composites have been observed and researched closely for many decades. Study of regenerated cellulose fibers and their composites is, on the other hand, relatively new. Regenerated cellulose fibers are prospective reinforcing material in the composite field due to their even quality and high purity. These fibers have good mechanical properties and also address the odour emission issue of the natural fibers. The development of biocomposites from regenerated cellulose fiber and thermoset resin synthesized from renewable resources has therefore been viewed with considerable interest. Such biocomposites can replace non-renewable resource based materials in future composite applications.
This thesis describes the development of biocomposites from regenerated cellulose fibers (Lyocell and Viscose) and thermoset resins synthesized from renewable resources (soybean oil and lactic acid). The performance and the properties of the composites were evaluated. Chemical surface treatments, alkali and silane, were performed on these fiber in order to improve the performance of the composites. Hybrid composites were also produced by mixing of two types of reinforcement.
The developed composites were evaluated through mechanical, thermal, viscoelastic and morphological properties among others. The results showed that the regenerated cellulose fiber thermoset biocomposites have reasonably good properties. Fibers before and after treatment were studied in detail. The silane treatment on these fibers improved the mechanical properties of the composites as the silane molecules act as a link between the fiber and resin which gives the molecular continuity across the interface region of the composite.
Keywords: Regenerated cellulose fibers, Surface modification, Alkali, Silane, Mechanical properties
University of Borås