Modeling the viscoelasticity of polyetherimide

Abstract

Viscoelasticity is a mechanical phenomenon where the material modulus varies with time and temperature. Modern experimental methods can determine material properties within certain time and temperature ranges, but modeling the viscoelastic behavior remains challenging, mainly because the data processing is complex and different materials have distinct properties. Using polyetherimide as an example and based on the change in the secondary bonds of polyetherimide in different viscoelastic stages, we proposed a new shift factor model in Arrhenius format with alterable activation energy. We also used two methods based on nonlinear least squares to obtain the Maxwell model of the polyetherimide, and we then used a novel method integrated with Laplace transforms and partial fraction decomposition to convert the Maxwell model into the Voigt model. The results of our model are reliable and self-consistent, showing its potential for modeling the viscoelasticity of other materials. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46102.

Investigation of residual stresses induced by composite forming using macro-micro simulation

“…Meantime, viscoelasticity in a resin releases a portion of the formed stresses. The Maxwell model in a Prony series mathematical format (equation (8)) integrated with the shift factor (equation (9)) is widely used to describe material thermo-viscoelasticity 25 …”

Stress Evolution of Amorphous Thermoplastic Plate during Forming Process

“…As a result, the viscoelasticity of the PEI can be predicted at any temperature by substituting Equation (9) into Equation (8). The viscoelasticity effect and the shift factor of the PEI have been comprehensively researched in [ 16 ]: …”

“…The time-related strain and stress are connected by a constitutive equation for linear viscoelasticity, as shown in Equation (12) [ 16 ]: …”

Nonlinear tensile behavior of cotton fabric reinforced polypropylene composites

“…To describe the nonlinear viscoelastic behavior of materials, scholars have optimized the above models by using a time-varying viscosity fluid or a fractional derivative method. 10,11 From an accuracy point of view, and especially from the facility of use, Paola and Pirrotta proposed a fractional derivative characterized by only two parameters to address the generalized Kelvin and Maxwell models. 12 Drozdov and Kalamlarov used nonlinear components instead of linear components and obtained a constitutive model to describe the nonlinear viscoelastic behavior of polymers.…”

“…These models were used to characterize the linear viscoelastic properties of materials and consist of a linear element such as a spring that obeys Hooke's law and a damper that act as a Newtonian fluid. To describe the nonlinear viscoelastic behavior of materials, scholars have optimized the above models by using a time‐varying viscosity fluid or a fractional derivative method 10,11 . From an accuracy point of view, and especially from the facility of use, Paola and Pirrotta proposed a fractional derivative characterized by only two parameters to address the generalized Kelvin and Maxwell models 12 .…”