Polylactide and polycaprolactone grafted starch – synthesis, characterization and degradation
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesisAlternative title
Polylaktid och polykaprolakton ympad stärkelse - syntes, karakterisering och nedbrytning (Swedish)
Pollution is one of the most important issues in the world today. Renewable and degradable plastics attract more attention to the research. Starch can not only be used as food but also it has many other applications. In papermaking industry, textile, food processing, adhesive industry and some other areas, starch has its place.
However starch-based materials show very poor mechanical properties due to their strong water absorption and poor interfacial adhesion with other components. This study aims to improve properties of starch-based materials. Starch granules surface were modified by lactic acid. Then polylactide and polycaprolactone were grafted on those surface modified starch granules. With the help of SEM, it was easy to notice that after grafting reactions, the smooth surface of starch granules became rough. However because of the purification process it was hard to calculate the grafting degree. Some films of starch, polylactide, polycaprolactone and grafted starch with different ratios were prepared and their properties and degradation behaviors were studied with DSC, Instron, SEM and FTIR. With PLA or PCL and surface grafting PLA or PCL in the matrix, water resistance of starch improved a lot. However maybe during the grafting process starch became more water soluble (gelatinized or amorphous) so water resistances of those films with grafted starch were less than those with raw starch granules. Films with grafted starch showed higher weight loss after degradation. The poor mechanical properties due to the severe phase separation between starch and PLA were, however, improved by grafting. It was also interest to find that films with 25% starch and 75% PCL showed good mechanical properties. The largest elongation at break and the largest tensile stress at tensile strength were shown by films with 25% st-g-PCL2 and 75%PCL.
Place, publisher, year, edition, pages
2011. , 27 p.
starch, polylactide, polycaprolactone, polyester, degradation
IdentifiersURN: urn:nbn:se:kth:diva-150818OAI: oai:DiVA.org:kth-150818DiVA: diva2:745521