Investigation of the effect of nano-clay type on the non-isothermal crystallization kinetics and morphology of poly(3(R)-hydroxybutyrate) PHB/clay nanocomposites

• Published in: Polymer bulletin (Berlin, Germany) Vol. 71; no. 6; pp. 1449 - 1470
• Main Author: Mohamed El-Hadi, Ahmed
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-06-2014; Springer; Springer Nature B.V
• Subjects: Applied sciences; Biodegradation; Bioplastics; Biopolymers; Brittleness; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Clay; Cold; Complex Fluids and Microfluidics; Composites; Cooling; Crude oil; Crystal structure; Crystallization; Degree of crystallinity; Density; Exact sciences and technology; Forms of application and semi-finished materials; Fourier transforms; Microscopy; Morphology; Nanocomposites; Nucleation; Optical microscopy; Organic Chemistry; Original Paper; Outdoor air quality; Physical Chemistry; Plasticizers; Plastics; Polyhydroxybutyrate; Polymer industry, paints, wood; Polymer matrix composites; Polymer Sciences; Radiation; Reagents; Renewable resources; Soft and Granular Matter; Spherulites; Stability analysis; Technology of polymers; Temperature; Thermal stability; Thermodynamic properties; Thermogravimetric analysis; Plasticizer; Poly(3; hydroxybutyrate) PHB; Crystallization kinetics; Morphology; Miscibility; Nano-clays; Clay; Montmorillonite; Ester polymer; Citrate; Butyrate(hydroxy)polymer; Crystallinity; Experimental study; Glass transition temperature; Composite material; Property formulation relationship; Thermal stability; Thermal properties; Additive; Melt crystallization; Spherulites; Aliphatic polymer; Nanocomposite; Kinetics; Crystal morphology; Nucleating agent
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-014-1135-0

PHB is a thermoplastic biopolymer produced by fermentation of renewable resources. Secondary crystallization during storage leading to an increased degree of crystallinity is a principal reason of PHB brittleness. In addition, pure PHB has no residues of catalysts, meaning low nucleation density and slow crystallization rates, leading to the formation of large spherulites with cracks and brittleness. To overcome the brittleness of PHB, polymer composites based on PHB, plasticizers, and nano-clays A and B were prepared by solvent casting. The addition of plasticizer decreases
T
g
from 5 to −13 °C in all composites. Furthermore, the addition of nano-clays acts as a nucleating agent to PHB. The effect of nano-clays A and B on spherulites morphology, thermal behavior, and crystal structure of PHB composites were tested by several techniques. Differential scanning calorimetry analysis shows that the addition of nano-clay A does not change the crystallization temperature and the crystallization half-time (
t
1/2
) of the PHB matrix but that nano-clay B accelerates the crystallization process. Thermogravimetric analysis revealed an increase in thermal stability of composites containing nano-clay B. Polarized optical microscopy showed that nano-clays serve as nucleating agents in PHB matrix. Therefore, the spherulites become smaller and the nuclei density increases at the selected crystallization temperature, compared to pure PHB.