Author, as appears in the article.: Morancho J, Ramis X, Fernández-Francos X, Salla J, Konuray O, Serra

Department: Química Analítica i Química Orgànica

URV's Author/s: Fernández Francos, Xavier / Serra Albet, Maria Angels

Keywords: Toughened epoxy Thermosets Rubber Resins Network structure Mechanism Kinetics Isothermal cure Gelation Epoxy resins Epoxy networks Dual-curing Cure Anhydride

Abstract: In the present work, we report the preparation and characterization of a new family of thermosets based on off-stoichiometric anhydride-epoxy formulations in the presence of an anionic initiator. Diglycidyl ether of bisphenol A (DGEBA) and hexahydro-4-methylphthalic anhydride (HHMPA) have been used as epoxy and anhydride comonomers, respectively, and 1-methylimidazole (1MI) has been used as anionic initiator. The isothermal curing kinetics and the thermal properties of the stoichiometric and the off-stoichiometric systems have been compared. The kinetics of the isothermal curing has been analyzed by differential scanning calorimetry (DSC) using an isoconversional method and the Sestak-Berggren equation to determine the activation energy, the frequency factor and the reaction orders. The materials obtained were characterized by DSC and dynamic mechanical analysis. Gelation during epoxy-anhydride condensation was determined by thermomechanical analysis. At the same curing temperature, the reaction is faster in the system with excess of epoxy groups. However, the glass transition temperatures of the partially cured stoichiometric system are greater. The gelation time of the off-stoichiometric system is shorter than that of the stoichiometric one. The results indicate that the dual-curing character of off-stoichiometric DGEBA/HHMPA thermosets with 1MI as anionic initiator makes them suitable for multistage curing processes with easy control of degree of cure and material properties in the intermediate stage and enhanced final material properties.

Thematic Areas: Zootecnia / recursos pesqueiros Thermodynamics Saúde coletiva Química Polymers and plastics Physical and theoretical chemistry Odontología Nutrição Medicina ii Medicina i Materials chemistry Materiais Interdisciplinar Geociências Farmacia Ensino Engenharias iv Engenharias iii Engenharias ii Engenharias i Educação Economia Dentistry (all) Condensed matter physics Ciências biológicas iii Ciências biológicas ii Ciências biológicas i Ciências ambientais Ciências agrárias i Ciência de alimentos Chemistry, physical Chemistry, analytical Biotecnología Biodiversidade Astronomia / física Arquitetura e urbanismo

licence for use: https://creativecommons.org/licenses/by/3.0/es/

ISSN: 14182874

Author's mail: xavier.fernandez@urv.cat angels.serra@urv.cat

Author identifier: 0000-0002-3492-2922 0000-0003-1387-0358

Record's date: 2023-07-31

Papper version: info:eu-repo/semantics/acceptedVersion

Link to the original source: https://link.springer.com/article/10.1007/s10973-019-08681-z

Licence document URL: http://repositori.urv.cat/ca/proteccio-de-dades/

Papper original source: Journal Of Thermal Analysis And Calorimetry. 138 (4): 2865-2872

APA: Morancho J, Ramis X, Fernández-Francos X, Salla J, Konuray O, Serra (2019). Curing and thermomechanical properties of off-stoichiometric anhydride-epoxy thermosets. Journal Of Thermal Analysis And Calorimetry, 138(4), 2865-2872. DOI: 10.1007/s10973-019-08681-z

Article's DOI: 10.1007/s10973-019-08681-z

Entity: Universitat Rovira i Virgili

Journal publication year: 2019

Publication Type: Journal Publications