The Effect of Fabrication Method and Hard-phase Properties on the Thermo-viscoelastic Performance of Polyurethane-based Shape Memory Polymer Used in Medical Scaffolds

Document Type : Original Article

Authors

1 Mechanical engineering department, TMU

2 mechanical engineering department

3 Mechanical engineering department, Tehran University

4 School of Medical Sciences, Tarbiat Modares University

5 mechanical engineering department, Tarbiat Modares University

Abstract

Shape memory polymers (SMPs) have the ability to store the deformation and recover the original shape. Shape memory behavior is associated with two features: shape recovery and stress recovery. Full shape recovery and increase the stress recovery value are the challenges ahead of the SMPs. In this paper, the polyurethane and polycaprolactone (PCL) were blended. The thermal stimulated SMPs ware fabricated by melt mixing and solution mixing method and thermo-viscoelastic behavior of SMPs ware analyzed. Two types of polyurethanes with the same chemical structure were used as the hard phase and polycaprolactone was used as the soft phase in SMP blend. The results show that the solution mixing method has advantages such as proper appearance without defect, free from cracks and cavities, higher storage and loss modulus values without fluctuations over temperature. The blend of PCL with low hardness polyurethane one showed better shape memory behavior. In order to investigate the shape memory effect, shape recovery test was carried out with 25% pre-strain at 60°C. Also, the stress recovery was carried out by 25% pre-strain at different temperatures (60°C, 45°C and 37°C) on the samples made by solution method. The stress-recovery function was highly affected by the deformation temperature. The maximum stress and maximum recovery rate were observed in the sample with a deformation temperature of 45°C. A stent was made by the solution method and its shape recovery results showed that recovery was done completely in less than 0.5 seconds at 60°C.

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Iranian Journal of Manufacturing Engineering
Volume 5, Issue 3
November and December 2018
Pages 32-43

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