Publication | Closed Access
Effect of Melt Processing on Crystallization Behavior and Rheology of Poly(3-hydroxybutyrate) (PHB) and its Blends
77
Citations
0
References
2002
Year
EngineeringDifferential Scanning CalorimetryMechanical EngineeringMelt TemperatureCrystallization BehaviorPolymer ProcessingRheologyThermodynamicsSolidificationPolymer ChemistryThermoanalytical MethodMaterials SciencePolymer BlendMelt ProcessingRheology ControlPolymer MeltMolar MassPolymer ScienceRheological PropertyPolymer CharacterizationPolymer PropertyThermal DegradationHydrothermal Processing
Poly(3-hydroxybutyrate) (PHB) is sensitive to high processing temperatures. This leads to a decrease in molar mass as well as a lower melt viscosity. The crystallization temperature shifts to lower values, and crystallization kinetics is slow. A mixture was developed in order to improve the manufacturing properties and the final product. The blends exhibit a slight reduction in molar mass because they have a lower melting point than pure PHB, and can be extruded at their melt temperature of 170 to 180°C. Then they immediately crystallize at 125 to 100°C. Differential scanning calorimetry (DSC) shows the effect of holding time in the melt on crystallization behavior. It has been shown that the crystallization time has to be longer in the case of PHB and shorter for the blends. Thermal degradation of PHB and its blends has been investigated using thermogravimetry analysis (TG). Derivative thermogravimetry coupled with TG (TG/DTG) curves show three decomposition stages for blends at 290, 340 and 445°C, respectively. Acetic acid, water, carbon dioxide and methane are produced by degradation at a higher temperature.