Effect of dynamic cross-linking on phase morphology and dynamic mechanical properties of polyamide 12/ethylene vinyl acetate copolymer blends

• Published in: Polymer bulletin (Berlin, Germany) Vol. 71; no. 1; pp. 151 - 166
• Main Authors: Bondan, Fabrício, Soares, Márcio R. F., Bianchi, Otávio
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2014; Springer; Springer Nature B.V
• Subjects: Applied sciences; Binary systems; Chambers; Characterization and Evaluation of Materials; Chemical reactions and properties; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Copolymers; Crosslinking; Crosslinking, vulcanization; Dicumyl peroxide; Dispersion; Dynamic mechanical properties; Ethylene vinyl acetates; Exact sciences and technology; Free radicals; High density polyethylenes; Low density polyethylenes; Mechanical properties; Morphology; Organic Chemistry; Organic polymers; Original Paper; Physical Chemistry; Physicochemistry of polymers; Polyamide resins; Polyethylene; Polymer blends; Polymer Sciences; Rheometers; Rubber; Scanning electron microscopy; Soft and Granular Matter; Solvent extraction processes; Surface tension; Temperature; Thermal analysis; Torque; Viscoelasticity; Dynamic cross-linking; EVA; PA12; Viscoelasticity; Polymer blends; Molecular structure; Interface tension; Crosslink density; Crosslinking; Experimental study; Vulcanization; Interface properties; Dynamic mechanical properties; Morphology; Aliphatic polymer; Concentration effect; Crosslinked polymer; Amide 12 polymer; Property structure relationship; Mechanical loss; Rheological properties
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-013-1051-8

Dynamic cross-linking of polyamide 12 (PA12) and ethylene vinyl acetate copolymer (EVA) blends in the mixing chamber of a torque rheometer was investigated. EVA was selectively cross-linked within the PA12 phase through free radical reactions using dicumyl peroxide. The torque level and temperature in the torque rheometer chamber were monitored to follow the evolution of the EVA cross-linking during the dynamic cross-linking process. The degree of cross-linking of EVA in the PA12/EVA materials was estimated based on the gel content (insoluble EVA fraction). The PA12/EVA phase morphology was investigated by scanning electron microscopy. The solid viscoelastic properties were investigated by dynamic mechanical thermal analysis (DMTA). The morphology, interfacial tension and viscoelastic results showed the immiscible nature of this system. The morphology of the blends was observed and the results revealed a two-phase system. The PA12/EVA 70/30 showed disperse-phase morphology, however a co-continuous phase was observed in blend ratios of 50/50 and 60/40. The dynamic cross-linking process resulted in a more stable EVA phase morphology with disperse and interconnected structures in the thermoplastic PA12 domains.