Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 100096

100096 - The Effect of Two-Way Shape Memory on the Healing of Poly (Ethylene-Co-Methacrylic Acid) and Polybutadiene Blend 

Abstract

Development in self-healing materials and smart composites has continuously improved for many decades and has given rise to many real-life applications with implications for engineering materials, structures, and human beings who rely on these technological innovations to further human endeavor. This study involves the use of intrinsic self-healing ability of poly (ethylene-co-methacrylic acid) thermoplastic, known by its commercial name as Surlyn 9520©, and combined two-way shape memory effect with Di cumyl-peroxide (DCP) cross-linked polybutadiene elastomer to achieve crack narrowing and closure with subsequent healing of the polymer blend surface. The simple batch mixing process resulted in an immiscible yet compatible blend, determined by two distinct melting peaks from DSC characterization and FTIR spectroscopy analysis. Different blends ratios of 80/20, 70/30, 60/40, 50/50 were investigated and characterized. However, the 80/20 blend was chosen to demonstrate the significance of the two-way shape memory effect, where a material experiences elongation upon cooling and contraction upon heating to achieve crack closure and effectual healing. Two sets of samples were studied; control Sample known as 2A and 2B samples were one time programmed to about 300% strain. Self-healing, which is a function of the poly(ethylene-co-methacrylic) acid component of the blend, was established for both sets of specimens. The flexural properties from three-point bending test indicate that although both sets of samples achieved good healing efficiencies, the 2B programmed samples displayed better healing efficiencies than the control by 30%. The polymer blend exhibited a two-way shape memory effect across a temperature window of -40oC and 100oC. This combined method of constrained elongation upon cooling and contraction upon heating was repeatable over at least three cycles tested. The 80/20 blend showed better performance with as high as 25.56% EUC in the second cycle. A three-point bending test was used to characterize the properties of both 2A and 2B groups, and the maximum load was used to evaluate healing efficiency for the various groups after each cooling and heating cycle. Regarding repeatability, the load specimens could carry, flexural stress and healing efficiency all decreased for all groups between the first and fourth cycles. The close then-heal strategy using two-way shape memory effect for the blend is very effective for small cracks but not so much for large macroscopic damages. From the results of characterization, it is evident that proper miscibility was not attained by the processing method used, as evidenced in the double melting peaks of the DSC and the SEM images, as well as mechanical tests. Nonetheless, the blend showed some compatibility between the constituent materials, allowing for some useful application.

Keywords: Shape memory Polymers, Composite, programmed samples, poly(ethylene-co-methacrylic) Acid. Self-healing, DSC Characterization, FTIR analysis.

Presenting Author: EMMANUEL IGBOKWE Southern University Baton Rouge LA

Presenting Author Biography: Emmanuel Igbokwe is a final Year Graduate Student of Southern University A&M College Baton Rouge LA. His Major is in Mechanical Engineering with specialty in Material Engineering.

Authors:

EMMANUEL IGBOKWE Southern University Baton Rouge LA
Patrick Mensah Southern University A&M College Baton Rouge LA.