Secondary crystallisation and degradation in P(3HB-co-3HV): an assessment of long-term stability

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Authors

Colleges, School and Institutes

Abstract

The effect of long-term storage, at a range of temperatures, on the thermal and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) is reported. P(3HB-co-3HV) was stored at -22, 7, 20, 50, 75, 100, 125 and 150 °C for 672 hours. Below 100 C, the observed increase in melting point, glass transition temperature, modulus and strength are due to the development of crystallinity via a secondary process and facilitated by increasing temperature. At 125 C, the processes of secondary crystallisation and degradation occur in parallel and there is an interplay between these processes, with the effects of degradation masked by the continuation of secondary crystallisation. At 150 C there is a deterioration in all the properties noted above and given the reduction in molecular weight (and discolouration), this can be attributed to degradation. The significant observation from these results is that the degradation process remains active well below the melting point and long-term stability of P(3HB-co-3HV) is not only affected by secondary crystallisation, but also degradation. In addition, as no significant changes to the thermal or mechanical properties were observed during storage at -22 and 7 °C it suggests that P(3HB-co-3HV) may be a suitable packaging material for frozen or refrigerated products.

Details

Original languageEnglish
JournalPolymer Journal
Publication statusPublished - 25 Jan 2018

Keywords

  • thermal properties, mechanical testing, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), stability, secondary crystallisation, thermal degradation