Characterization of processing, rheological and dynamic mechanical thermal properties of PVC stabilized with polyphenol-based thermal stabilizer

The effects of natural polyphenol-based thermal stabilizer synthesized from tannin, a flavonoid-type natural polyphenol, on the processing, rheological and viscoelastic behaviors of polyvinyl chloride (PVC) were investigated in this work. Rheological properties of PVC were studied via three different types of rheometry techniques: torque by an instrumented batch mixer, dynamic oscillating shear rheometry, and dynamic mechanical thermal analysis (DMTA). In the course of the investigation, rotational melt rheological properties in terms of shear complex viscosity, storage modulus, and loss modulus were studied in order to evaluate the performance of tannin-cadmium complex as bio-based PVC additive and as a thermal stabilizer. Experimental results of this study for all PVC formulations with this derivative at loading percentages of 1, 2, and 3 parts per hundred of PVC resin (phr) reveal that the processing and dynamic thermal stability of PVC monitored by torque curves and rheological tests can be enhanced with the addition of this derivative. Rheological behavior of PVC stabilized with tannin derivative is superior or very close to that of PVC stabilized with trade-grade thermal stabilizer. Additionally, DMTA was carried out to see the effect of tannin-cadmium at 2 phr on the thermo-mechanical properties of PVC. All DMTA-related terms such as storage modulus and damping factor and glass transition region point out that the PVC has good viscoelastic properties compared to that of PVC stabilized with commercial thermal stabilizer.