This PhD project investigated the effects of a co-continuous phase structure on the ductility of poly(lactic acid) (PLA) blends. An empirical model was used to predict the phase inversion point of the blends. The co-continuous phase morphology was first observed in polybutylene succinate(PBS)/PLA blends. With as little as 10 wt% of PBS, PBS/PLA blends achieved a dramatic improvement in ductility, over 250% elongation-to-break. Clay additives were incorporated in PBS/PLA blends. Clay was found out to affect the compatibility and co-continuous phase morphology of PBS/PLA blends. The clay dispersion was found to have an intercalated and exfoliated structure at a PBS/PLA composition ratio of 20/80. The clay particles increased the mixing conditions between the polymers by producing a finer structure, but also destroyed the co-continuous phase morphology, resulting in a substantial decrease in elongation-at-break. PLA was then blended with Poly(butylene adipate-co-terephthalate) (PBAT) to examine whether the co-continuous phase model could also be applied to other PLA-polymer blends. From the melt viscosity ratio of PLA and PBAT in the processing regime used in the study, the predicted phase inversion value was 19 wt% of PBAT. This value was verified by the results of mechanical properties, where results for elongation-to-break show a dramatic rise from around 10% up to 300% in the composition range between 10 and 20wt% of PBAT. Polyhydroxyalkanoate (PHA) was also blended with PLA and this project investigated how co-continuous phase morphology affects the blends of two brittle polymers. It was found that when PHA content ranged from 10 to 20wt%, the brittle-brittle polymer blends showed ductile behaviour due to a plane stress effect.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:747900 |
| Date | January 2017 |
| Creators | Deng, Yixin |
| Publisher | Loughborough University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://dspace.lboro.ac.uk/2134/33338 |
Page generated in 0.0018 seconds