Rheological Measurements and Structural Analysis of Polymeric Materials

Abstract

Rheological measurements of polymer melts are widely used for quality control and the optimization of processing. Another interesting field of rheology is to provide information about molecular parameters of polymers and the structure build-up in heterogeneous polymeric systems. This paper gives an overview of the influence of molar mass, molar mass distribution and long-chain branching on various rheological characteristics and describes the analytical power following from established relations. With respect to applications, we discuss how rheological measurements can be used to gain insight into the thermal stability of a material. A special impact lies in the demonstration, how long-chain branching can be analyzed using rheological means like the zero-shear viscosity as a function of molar mass and strain hardening occurring in elongation. For contributions to branching analysis, the thermorheological behavior and activation energies are particularly discussed. The use of elastic quantities in the case of mechanical pretreatment effects is briefly addressed. The influence of fillers on recoverable properties in the linear range of deformation is analyzed and the role of their specific surface area for interactions described. It is shown how the fundamental results can be applied to study the state of nanoparticle dispersions obtained under special conditions. Furthermore, it is demonstrated that the findings on polymer/filler systems are the base of structure analyses in heterogeneous polymeric materials like polyvinylchloride (PVC) and acrylonitrile–butadiene–styrene copolymers (ABS).

Rheological Analysis of the Synthesis of High-Molecular-Weight Epoxy Resins from Modified Soybean Oil and Bisphenol A or BPA-Based Epoxy Resins

“…However, the equation η(M w a ) for that part of the plot for ESBO_BPA process does not follow the power-law dependence, which is characteristic for the creation of only linear products. Simultaneously, as indicated in studies cited in the literature [30], it does not mean that the creation of such products in significant amounts does not proceed. Next to the formation of linear products, probably the process of branching and tangling of long chains takes place.…”

“…) has a great effect on η0, due to the significant power-law dependence of η0 on [30]. Taking into consideration that dependence, Figure 7 presents the change of viscosity and average-weight molecular mass during the ESBO_BPA and SMEG_EPR process.…”

“…Rheological studies have found various applications for the research on chemical and physical gelation processes of numerous polymeric materials [29][30][31]. The concept of gelation of material during the curing process is understood as a stage of the reacting system upon the certain degree of conversion, resulting in the incipient formation of an infinite network of cross-linked polymer molecules, resulting in an irreversible transformation of the sample from viscous liquid to a rubbery/elastic solid state [32].…”

A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer

“…Furthermore, the time at the beginning of sudden growth of G′ decreased with increasing resin temperature. Münstedt [ 31 ] indicated that the growing G′ explained a surge in molar mass induced by partial crosslinking of molecules. Since the resin temperature was above 310°C in this experiment, the COP melts are thermally unstable.…”

Constitutive Equations for Analyzing Stress Relaxation and Creep of Viscoelastic Materials Based on Standard Linear Solid Model Derived with Finite Loading Rate

“…The applications of polymers are still advancing and increasing rapidly, thanks to their exceptional mechanical properties. The mechanical behaviors of all polymers are viscoelastic, meaning that they exhibit time-dependent mechanical behaviors of both viscous fluids and elastic solids [ 1 , 2 , 3 , 4 , 5 ]. By measuring and analyzing the viscoelastic behaviors (such as stress relaxation and creep) of a polymer when it is subjected to loading, its viscoelastic properties can be quantitatively evaluated [ 6 , 7 , 8 , 9 , 10 ].…”