A hygro-thermo-mechanical constitutive model for shape memory polymers filled with nano-carbon powder

• Main Authors: Jianping Gu, Xiaopeng Zhang, Hao Duan, Mengqi Wan, Huiyu Sun
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2021-08-01
• Series: International Journal of Smart and Nano Materials
• Subjects: shape memory polymer composites; nano-carbon powder; hygro-thermo-mechanical constitutive model; thermodynamics; internal state variables
• Online Access: http://dx.doi.org/10.1080/19475411.2021.1958089
• ISSN: 1947-5411; 1947-542X

The nano-carbon powders are often used as fillers to endow the shape memory polymers (SMPs) with electroconductivity. It has been found that the shape memory effects (SMEs) of SMPs filled with nano-carbon powder can be triggered both by temperature and by water. To reveal the driving mechanism of SMEs, a constitutive model for describing the thermally activated and moisture activated SMEs of these shape memory polymer composite (SMPCs) is developed here. Because both of the SMEs share the same driving mechanism, the variable moisture is incorporated into the framework of a thermo-mechanical modeling approach to disclose the effect of moisture on the thermoviscoelastic properties. The SMPCs are regarded as isotropic materials and the effect of carbon powder on the mechanical properties of the matrix is also considered in the paper. Because the complete recovery may not be reached even they are exposed to the stimulus environment long enough, the blocking mechanism is also considered here. This is the mainly new contribution compared to the early work. Using the method of parameter determination presented here, the effectiveness of the proposed hygro-thermo-mechanical constitutive model is confirmed by comparing the model results with the test data of uniaxial deformation from the literature.