Synthesis and characterization of shape memory polyurethanes

Abstract

Shape memory polymers (SMPs) have attracted extensive attention from basic and fundamental research to industrial and practical applications because they have emerged as a cheap and efficient alternative to well-known metallic shape-memory alloys. Among them, shape memory polyurethanes (SMPUs) own different applications such as the textile finishing, adhesives, coatings, automotive, furniture, construction, and thermal insulation and footwear industries, due to it can be synthesized with different types of molecular architectures by manipulating their composition and choosing properly the chemical structure of their components. In this work, the synthesis and characterization of shape memory polyurethanes, based on two-step polymerization, is reported. The hard segment of SMPU was composed of diisocyanate and a chain extender. On the other hand, the soft segment was prepared by polyols with different molecular weights. Depending on the structure of the synthetized polyurethanes, the materials presented different properties. Thermal characterization was performed by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Furthermore, mechanical properties and shape memory effect were also determined by Dynamic Mechanical Analysis (DMA) and Thermo-Mechanical Analysis (TMA).

Cyclic Thermomechanical Analysis of Polyethylene Glycol Based Shape Memory Polymers

“…Sample 5 was chosen because at a rate of 5°C/min from 0 to 150°C. The temperaturedependent recovery stress is measured [9,10]. Schematic representation of constrained recovery test is shown in Figure 3.…”