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Table 2 Molecular weight (number average M n and weight average M w ) and molecular weight change \( \left(\left(\frac{{\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{0}}\hbox{-} {\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{t}}}{{\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{0}}}\right)\mathbf{x}\ \mathbf{100}\right) \) of various PHB samples as a function of thermal treatment at 170°C.

From: Feasibility study of an alkaline-based chemical treatment for the purification of polyhydroxybutyrate produced by a mixed enriched culture

Sample Chemical treatment PHB purity [wt.%] Time of thermal treatment at 170°C [min] M n [kg/mol] M w [kg/mol] \( \left(\frac{{\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{0}}\hbox{-} {\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{t}}}{{\boldsymbol{M}}_{\boldsymbol{n},\boldsymbol{0}}}\right)\mathbf{x}\ \mathbf{100} \) [%]
Commercial PHB - 99 0 182 647 0
1 169 583 7
3 175 541 4
5 119 391 35
10 150 435 18
15 135 373 26
PHB from biomass - 67 0 135 224 0
1 51 111 62
3 33 62 76
5 30 42 78
10 25 34 81
15 19 25 86
Solvent 99 0 915 1755 0
1 883 1731 3
3 824 1573 10
5 771 1562 15
10 516 1144 44
15 560 1255 39
0.2 M NaOH 85 0 119 315 0
1 19 39 84
3 8 13 93
5 6 8 95
10 2 3 98
15 1.8 2.2 98
0.2 M NaOH + 0.2% SDS 95 0 163 484 0
1 45 73 72
3 14 23 91
5 11 20 93
10 4 8 98
15 3 4 98
  1. Water content in the samples was in between 0.01 and 0.02 wt.%.