Preparation And Characterization Technique Of Thermoset Shape Memory Cyanate Ester

Shape memory polymers are a new kind of smart material, which have huge development potential and a promising future. Since shape memory polymer shows outstanding advantages of low-cost, light weight, high deformable ability, easy to drive and controllable performance, it has become one of the focus of the smart materials. In this work, a series of shape memory cyanate polymers were prepared by cyanate ester and varying content of two different modifiers. The microstructure, thermal property, mechanical property and shape memory property of the shape memory cyanate resins were investigated by Fourier Transform Infrared spectroscopy, Differential Scanning Calorimetry, Thermal Gravimetric Analysis, Dynamic Mechanical Analysis and tensile test. The relationship between the microstructure and macroscopic properties were illuminated. This article aims to broaden the usage of shape memory polymer materials in aerospace application, especially to increase the heat resistance of shape memory polymer materials.It was found that shape memory cyanate resins we prepared showed excellent mechanical properties, high glass transition temperature and heat resistance. The glass transition temperature can be adjusted from 156.9℃to 259.6℃with PEG, and the tensile strength increased to 50MPa or more with the modifier HTBN. The initial temperature of thermal decomposition came up to 300℃, which is enough high for the application in aerospace fields. Tensile strength ranged from 30MPa to 75MPa, and elastic modulus ranged from 0.8GPa to 1.6GPa, which are consistent with standard engineering plastics. Small amount of modifier could increase the cross-linking density, and enhance the mechanical property of the polymer in the same time. With the increasing modifier, the cross-linking density decreased, and then resulted in the decrease of tensile strength, but the fracture elongation increased.The shape memory effect of the shape memory polymer was investigated, the results showed that the polymer we prepared is viscoelastic and shows a good shape memory effect, as the shape recovery time is less than 65s and the shape recovery rate reaches 95%. In addition, the modifier content has little influence on the shape recovery rate, which means that the shape recovery rate of all polymers with different glass transition temperature we studied are high enough for application. We also found that the aging process can be slower by increasing the deformation temperature and the drive force can be increased by a short-term holding with an external restraint on the specimen.On the principle of shape memory, the architecture and entropy of the SMP during the shape memory process was studied, it was showed that the tendency to increase of the system entropy is the nature of the shape memory effect. The infrared spectrum of the cyanate ester polymer proved that the most important structural feature is the triazine ring, which is also a cross-linking points. According to this we established a shape memory cyanate ester molecular model. The glass transition process of the system was simulated and the glass transition temperature of the simulation is close to the experimental data, indicating that this model is reasonable and the molecular dynamics simulations method of shape memory polymer is feasible for future study.