Sustainable self‐curing epoxy adhesives from Chios natural Mastic (Pistacia lentiscus L.)

Abstract

This study outlines a method for the epoxidation of poly-beta-myrcene, a biopolymer that can be easily extracted from the natural resin of the Chios Mastic tree (Pistacia lentiscus L.). The resulting epoxidation products are self-curing, and have a nearly 100% green carbon content. These Mastic Epoxide products (MASTEP) have the potential to be useful thermosetting resins. One specific product (MASTEP A), was used as an adhesive to create Single Lap Joints, which were then subjected to tensile shear stress tests. MASTEP A was found to be 25%-83% stronger than three commonly used conventional or "semigreen" epoxy adhesives. Another specific product (MASTEP B), was found able to be thermally converted into a semi-crystalline form. In order to clarify the 3D chemical structure of MASTEP, IR, and DSC investigations were conducted. The entire production process was designed to be environmentally friendly. The results of this research represent a significant advancement in the development of environmentally friendly epoxies and pave the way to a wide range of potential further research.

Assessing the potential of Chios natural mastic for the production of sustainable epoxy composite adhesives

“…The final product (10 g MASTEP D), dissolved in ethyl acetate‐ simply called “MASTEP” for the rest of this work‐ was used as it was or as a matrix to produce adhesive composites in order to manufacture lap joints. This adhesive is a sustainable one‐component epoxy, able to self‐cure in a single stage, at 140°C/3 h 41 …”

A sustainable alternative? A comparative life cycle assessment of epoxy adhesives

“…On the contrary, for MASTEP there is no need for component B, since MASTEP is self-hardening, and as for the-unique-component A, this comes from a natural resin with a minimally burdensome epoxidation method for the environment. 46 Due to these reasons, the already reported result of the comparative analysis of the production cycle of these materials looks normal and expected.…”

“…Curing was carried out at 140 C/3 h for MASTEP, and 50 C/24 h for CONEP. 46 Tensile shear stress tests were performed by an INSTRON 4301 tester and gave ultimate shear strength values of 7.1 MPa for MASTEP, and 5.7 MPa for CONEP, corresponding to 2.556 kN, and 2.052 kN load, respectively. Due to the form of the load-displacement curve, this ultimate strength is also strength at break.…”

“…The only multi-product output was in the case of MASTEP production (scenario 2). 46 The assessment procedure has followed ISO 14040 and 14044 standards provisions.…”

“…42 Poly-beta-myrcene can be isolated, characterized, 43,44 and epoxidized resulting in a one-component (self-curing) epoxy with excellent adhesive properties. [45][46][47] The aim of the current work was to assess and evaluate the life cycle of poly-beta-myrcene from the cradle to the gate and compare the results with those of a competing conventional epoxy, as well as with the results of a literature case involving a bio-based epoxy. These comparisons show that epoxidized poly-beta-myrcene is a highly promising and environmentally friendly product.…”