Table 3. Thermal Properties of the Electrospun Fiber Mats of Commercial Poly(3-hydroxybutyrate) (PHB), Commercial PHBV2 with 2 mol % 3-Hydroxyvalerate (3HV) Content, and Cheese Whey (CW)-Derived Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 3HV Contents of 20 mol % (PHBVCW20), 40 mol % (PHBVCW40), and 60 mol % (PHBVCW60) in Terms of Melting Temperature (Tm), Enthalpy of Melting (ΔHm), Crystallization Temperature (Tc), Enthalpy of Crystallization (ΔHc), Cold Crystallization Temperature (Tcc), and Cold Crystallization Enthalpy (ΔHcc)b,c.
| first heating endotherm |
cooling exotherm |
second heating endotherm |
||||||
|---|---|---|---|---|---|---|---|---|
| biopaper | Tm (°C) | ΔHm (J/g) | Tc (°C) | ΔHc (J/g) | Tcc (°C) | ΔHcc (J/g) | Tm (°C) | ΔHm (J/g) |
| commercial PHBa | 169.1 ± 0.9a | 64.1 ± 1.1a | 110.2 ± 0.9a | 59.3 ± 2.0a | - | - | - | - |
| commercial PHBV2 | 170.0 ± 0.8a | 79.4 ± 1.5b | 115.5 ± 0.4b | 85.1 ± 1.7b | - | - | 170.7 ± 0.6a | 89.7 ± 1.0a |
| PHBVCW20 | 154.2 ± 0.5b | 71.2 ± 0.3c | 82.3 ± 1.2c | 33.1 ± 1.4c | 69.3 ± 0.2 | 20.3 ± 0.7 | 128.0 ± 0.5b // 153.8 ± 1.1c | 49.8 ± 1.5b |
| PHBVCW40 | 67.7 ± 0.3c // 139.3 ± 0.4d | 67.1 ± 0.8d | 81.2 ± 0.7c // 41.2 ± 0.4d | 7.2 ± 0.7d | - | - | 152.6 ± 1.3c | 6.3 ± 0.3c |
| PHBVCW60 | 80.6 ± 0.2e | 39.9 ± 0.6e | 41.4 ± 0.6d | 3.6 ± 0.3e | - | - | 131.0 ± 0.4d | 1.2 ± 0.1d |
a
Data reported in a previous study.50
b
Different letters (a–e) in the same column indicate a significant difference among the samples (p < 0.05).
c
Dashes mean not measured for the case of PHB or thermal transition not unambiguously detected for the rest of samples.