Trade-off Between Limonene-based Reprocessable and Non-Reprocessable Epoxy Thermosets: Role of Aliphatic Diamines in Polymer Networks Design
Category
Sciences and Technology
Department
Polymer Chemistry
Student Status
Graduate
Research Advisor
Dr. Ram K. Gupta
Document Type
Event
Location
Governors
Start Date
10-4-2025 9:10 AM
End Date
10-4-2025 9:30 AM
Description
The increasing demand for sustainable materials, driven by environmental concerns and the rapid depletion of fossil fuel resources, has led to significant advancements in the fabrication of bio-based thermosets. Renewable alternatives, such as limonene-derived epoxy prepolymers, offer a promising replacement for petroleum-based thermosetting polymers, exhibiting comparable mechanical strength, thermal stability, and chemical resistance for applications in films, composites, coatings, and adhesives. This study presents the synthesis and characterization of limonene-based epoxy prepolymers through a two-step process, followed by their thermal crosslinking with various aliphatic diamines to fabricate thermosets. Incorporating cystamine, a disulfide-containing diamine, facilitated the formation of a covalent adaptable network via disulfide metathesis, yielding a reprocessable thermoset with self-healing capabilities, recyclability, and an extended lifespan. In contrast, thermosets cured with conventional aliphatic diamines formed permanently crosslinked networks with enhanced mechanical strength, thermal stability, and chemical resistance, making them suitable for high-performance applications requiring long-term durability with a maximum tensile strength of 11.62 MPa at an elongation of 22.2 %. Differential scanning calorimetry (DSC) was employed to elucidate the curing kinetics and crosslinking behavior, while thermogravimetric analysis (TGA) confirmed the excellent thermal stability of the synthesized materials. Additionally, dynamic mechanical analysis (DMA) and tensile testing demonstrated desirable mechanical properties. The absolute value of the glass transition temperature (Tg) determined from DMA analysis was 18 ℃, above which the malleable thermoset exhibited dynamic behavior due to disulfide bond exchange. Furthermore, the reprocessable thermoset exhibited a maximum tensile strength of 3.1 MPa at an elongation of 65 % and excellent reprocessability. Overall, this study highlights the potential of limonene-derived epoxy thermosets as sustainable alternatives, offering robust properties such as reprocessability, self-healing, and high-performance networks.
Trade-off Between Limonene-based Reprocessable and Non-Reprocessable Epoxy Thermosets: Role of Aliphatic Diamines in Polymer Networks Design
Governors
The increasing demand for sustainable materials, driven by environmental concerns and the rapid depletion of fossil fuel resources, has led to significant advancements in the fabrication of bio-based thermosets. Renewable alternatives, such as limonene-derived epoxy prepolymers, offer a promising replacement for petroleum-based thermosetting polymers, exhibiting comparable mechanical strength, thermal stability, and chemical resistance for applications in films, composites, coatings, and adhesives. This study presents the synthesis and characterization of limonene-based epoxy prepolymers through a two-step process, followed by their thermal crosslinking with various aliphatic diamines to fabricate thermosets. Incorporating cystamine, a disulfide-containing diamine, facilitated the formation of a covalent adaptable network via disulfide metathesis, yielding a reprocessable thermoset with self-healing capabilities, recyclability, and an extended lifespan. In contrast, thermosets cured with conventional aliphatic diamines formed permanently crosslinked networks with enhanced mechanical strength, thermal stability, and chemical resistance, making them suitable for high-performance applications requiring long-term durability with a maximum tensile strength of 11.62 MPa at an elongation of 22.2 %. Differential scanning calorimetry (DSC) was employed to elucidate the curing kinetics and crosslinking behavior, while thermogravimetric analysis (TGA) confirmed the excellent thermal stability of the synthesized materials. Additionally, dynamic mechanical analysis (DMA) and tensile testing demonstrated desirable mechanical properties. The absolute value of the glass transition temperature (Tg) determined from DMA analysis was 18 ℃, above which the malleable thermoset exhibited dynamic behavior due to disulfide bond exchange. Furthermore, the reprocessable thermoset exhibited a maximum tensile strength of 3.1 MPa at an elongation of 65 % and excellent reprocessability. Overall, this study highlights the potential of limonene-derived epoxy thermosets as sustainable alternatives, offering robust properties such as reprocessability, self-healing, and high-performance networks.
