Degradation of _L-polylactide during melt processing with layered double hydroxides

TY - JOUR

T1 - Degradation of L-polylactide during melt processing with layered double hydroxides

AU - Gerds, Nathalie Christiane

AU - Katiyar, Vimal

AU - Bender Koch, Christian

AU - Hansen, Hans Chr. Bruun

AU - Plackett, David

AU - Larsen, Erik Huusfeldt

AU - Risbo, Jens

N1 - 3rd International Conference on Biodegradable and Biobased Polymers (BIOPOL-2011) - Strasbourg 2011

PY - 2012/10

Y1 - 2012/10

N2 - PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium-aluminum layered double hydroxide (Mg-Al-LDH-C 12), the corresponding carbonate form (Mg-Al-LDH-CO 3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer surfaces and catalytically active Mg site centers are causative factors for PLA degradation. Interestingly, the release of water under the processing conditions was found to have a rather small effect on the PLA degradation. Low loadings of sodium laurate also caused PLA degradation indicating that carboxylate chain ends may be active degrading agents. Phosphate treatment of laurate-modified LDH was investigated and this may be a promising way of reducing PLA degradation, thereby making such processes more practically realistic.

AB - PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium-aluminum layered double hydroxide (Mg-Al-LDH-C 12), the corresponding carbonate form (Mg-Al-LDH-CO 3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer surfaces and catalytically active Mg site centers are causative factors for PLA degradation. Interestingly, the release of water under the processing conditions was found to have a rather small effect on the PLA degradation. Low loadings of sodium laurate also caused PLA degradation indicating that carboxylate chain ends may be active degrading agents. Phosphate treatment of laurate-modified LDH was investigated and this may be a promising way of reducing PLA degradation, thereby making such processes more practically realistic.

KW - LDH

KW - PLA

KW - Degradation

KW - Additive

KW - Catalytic depolymerization

U2 - 10.1016/j.polymdegradstab.2012.04.014

DO - 10.1016/j.polymdegradstab.2012.04.014

M3 - Journal article

SN - 0141-3910

VL - 97

SP - 2002

EP - 2009

JO - Polymer Degradation and Stability

JF - Polymer Degradation and Stability

IS - 10

ER -