International Journal of Polymer Science / 2013 / Article / Tab 1

Research Article

Preparation of Higher Molecular Weight Poly (L-lactic Acid) by Chain Extension

Table 1

The influences of process conditions on poly(lactic acid) after chain extension.

Runa (10−4 g/mol) NCO / OH bt (min) M (10−4 g/mol) / Chain-extension efficiency (%)Insoluble content (wt%)

a121.520−1417.916.32.068.92.2
a22320−1458.712.11.442.63.0
a32620−14510.520.31.952.23.6
a42820−1399.915.21.545.73.9
a52610−1405.48.31.647.92.2
a62630−1425.99.61.652.84.4
a72640−1416.111.11.856.62.2
a83620−1426.310.71.772.83.6
a94620−1406.712.51.872.73.8
a105620−1397.012.61.876.74.1

Reaction temperature: 175°C, nitrogen atmosphere; bmole ratio of –NCO to –OH.

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