Kinetic analysis of self-healing in vitrimers based on the recovery of mode I fracture toughness
Topic(s) : Special Sessions
Co-authors :
A. M. SALEH (SPAIN), Daniel SANCHEZ-RODRIGUEZ , Jordi FARJAS , A. REKONDO , Ruiz De Luzuriaga ALAITZ (SPAIN), Pere MAIMI (SPAIN), Josep COSTA (SPAIN)Abstract :
The need for more sustainable materials encouraged Leiber and co-workers to introduce a new generation of self-healing thermosets based on covalent adaptive networks (CANs), so called vitrimers [1]. The capability to rearrange the atomic bonds above the topological transition temperature leads to non-existing phenomena in traditional thermosets as the ability to reshape, stress relaxation or self-healing.
Different published approaches aimed to assess the self-healing capability of vitrimers [2]. In this work, we introduce a new methodology to assess the time-temperature-pressure dependence of self-healing of a disulfide containing epoxy vitrimer supplied by CIDETEC (Donostia-San Sebastian, Spain) [3]. The approach relies on the study of the mode I fracture toughness recovery using a single edge notched bend (SENB) specimen.
To avoid buckling and bleeding of the samples during healing, we have designed a tailored mold with accurate heating and cooling control. The recovered fracture toughness in terms of the time-temperature history and applied pressure is at the root of a kinetic isoconversional method to predict self-healing.
Based on the kinetic study by Rodriguez et al. [4], we have made use of the processing and reprocessing maps for this particular vitrimer to define the initial time and temperature for curing and healing the specimens. The work validates the healing kinetics of disulfide containing epoxy vitrimer based on various temperature (150 ⁰C, 175 ⁰C, 200 ⁰C, and 225 ⁰C) and durations of time (1 min, 2 min, 5 min, 30 min, and 8 h). The pressure-assisted surface contact was kept constant at a pressure of 3 MPa in all the experiments. Finaly, we introduce a contour diagram in the healing time-temperature space. This work will deepen in the understanding of the phenomena and will guide the definition of suitable thermal stories for repair of vitrimers, or vitrimer reinforced composites.
Different published approaches aimed to assess the self-healing capability of vitrimers [2]. In this work, we introduce a new methodology to assess the time-temperature-pressure dependence of self-healing of a disulfide containing epoxy vitrimer supplied by CIDETEC (Donostia-San Sebastian, Spain) [3]. The approach relies on the study of the mode I fracture toughness recovery using a single edge notched bend (SENB) specimen.
To avoid buckling and bleeding of the samples during healing, we have designed a tailored mold with accurate heating and cooling control. The recovered fracture toughness in terms of the time-temperature history and applied pressure is at the root of a kinetic isoconversional method to predict self-healing.
Based on the kinetic study by Rodriguez et al. [4], we have made use of the processing and reprocessing maps for this particular vitrimer to define the initial time and temperature for curing and healing the specimens. The work validates the healing kinetics of disulfide containing epoxy vitrimer based on various temperature (150 ⁰C, 175 ⁰C, 200 ⁰C, and 225 ⁰C) and durations of time (1 min, 2 min, 5 min, 30 min, and 8 h). The pressure-assisted surface contact was kept constant at a pressure of 3 MPa in all the experiments. Finaly, we introduce a contour diagram in the healing time-temperature space. This work will deepen in the understanding of the phenomena and will guide the definition of suitable thermal stories for repair of vitrimers, or vitrimer reinforced composites.