The goal of this paper was to establish a metric, which we refer to as the resilience parameter, to evaluate the ability of a material to retain tensile strength after damage recovery for shape memory polymer (SMP) systems. In this work, three SMP blends created for the additive manufacturing process of fused filament fabrication (FFF) were characterized. The three polymer systems examined in this study were 50/50 by weight binary blends of the following constituents: (1) polylactic acid (PLA) and maleated styrene-ethylene-butylene-styrene (SEBS-g-MA); (2) acrylonitrile butadiene styrene (ABS) and SEBS-g-MA); and (3) PLA and thermoplastic polyurethane (TPU). The blends were melt compounded and specimens were fabricated by way of FFF and injection molding (IM). The effect of shape memory recovery from varying amounts of initial tensile deformation on the mechanical properties of each blend, in both additively manufactured and injection molded forms, was characterized in terms of the change in tensile strength vs. the amount of deformation the specimens recovered from. The findings of this research indicated a sensitivity to manufacturing method for the PLA/TPU blend, which showed an increase in strength with increasing deformation recovery for the injection molded samples, which indicates this blend had excellent resilience. The ABS/SEBS blend showed no change in strength with the amount of deformation recovery, indicating that this blend had good resilience. The PLA/SEBS showed a decrease in strength with an increasing amount of initial deformation, indicating that this blend had poor resilience. The premise behind the development of this parameter is to promote and aid the notion that increased use of shape memory and self-healing polymers could be a strategy for mitigating plastic waste in the environment.
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THE EFFECT OF TWO-WAY SHAPE MEMORY ON THE HEALING OF POLY (ETHYLENE-CO-METHACRYLIC ACID) AND POLYBUTADIENE BLEND
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 selfhealing 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%.
more » « less- Award ID(s):
- 1946231
- NSF-PAR ID:
- 10404168
- Date Published:
- Journal Name:
- AMERICAN SOCIETY OF COMPOSITE 37TH CONFERENCE
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.12783/asc37/36419
