Structural characterization and mechanical properties of dextrin-graft-poly(butyl acrylate-co-styrene) copolymers

• Published in: Express polymer letters Vol. 13; no. 3; pp. 235 - 247
• Main Authors: David, A., Meimoun, J., Delaunay, T., Wiatz, V., Saint-Loup, R., Parcq, J., Descamps, N., Favrelle, A., Bonnet, F., Stoclet, G., Lourdin, D., Zinck, P., Gaucher, V.
• Format: Journal Article
• Language: English
• Published: Budapest Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Department of Polymer Engineering 01.03.2019; BME-PT Hungary; Budapest University of Technology
• Series: eXpress Polymer Letters
• Subjects: Acrylics; Amorphous materials; Biopolymers, biocomposites; Carbohydrates; Catalysis; Chemical and Process Engineering; Chemical industry; Chemical Sciences; Chemical synthesis; Composition; Copolymerization; Copolymers; Dextrin; Embrittlement; Emulsion polymerization; Engineering Sciences; Graft copolymers; Hydroxyl groups; Macromolecules; Material chemistry; Materials; Mechanical properties; Moisture content; Molecular chains; Molecular structure; Molecular weight; Morphology; Polybutyl acrylates; Polymer blends; Polymers; Polymethyl methacrylate; Structural analysis; structure; Styrenes; Substrates; Textile research; thermal behaviour; Thermodynamic properties; Transmission electron microscopy; X-ray scattering; grafted starch; structural organization; water sorption; biopolymers; mechanical behavior
• ISSN: 1788-618X; 1788-618X
• DOI: 10.3144/expresspolymlett.2019.20

Dextrin/starch-graft-poly(butyl acrylate-co-styrene) copolymers have been synthesized by radical graft copolymerization and their structure and mechanical properties are reported. High molecular weight grafted chains formation is favored, leading to a low degree of substitution of starch hydroxyl groups. Wide-Angle-X-ray Scattering (WAXS) analysis indicates that all materials are amorphous and Transmission Electron Microscopy (TEM) investigations reveal a two-phase morphology. This is further confirmed by the presence of two glass transitions, one related to the starch/dextrin macromolecules and sensitive to water content, and one assigned to the grafted polymers that is composition dependent. Water uptake is controlled by dextrin/starch content but diffusivity increases with the butyl acrylate ratio. The mechanical behavior is dependent on monomer ratio, and water content. Increasing butyl acrylate ratio improves the ductility of the sample while materials become brittle as soon as styrene ratio is predominant in the grafted chains. While no effect of molecular weight of starch substrate on structure and thermal behavior is evidenced, dextrin-based materials are slightly more ductile than starchbased ones. The interest of using dextrin instead of starch is further highlighted by a lower viscosity of the reactive medium, together with an improved processability, as structural materials can be obtained over a wider range of composition than with native starch.