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Hoseini Maryam, Haghtalab.Ali, Family Navid
Influence on compounding methods on rheology and morphology of linear low density polyethylene/poly(lactic acid)

Appl. Rheol. 26:6 (2016) 64746 (8 pages)

Linear low density polyethylene (LLDPE)/poly lactic acid (PLA) blends were prepared via different melt mixing methods. The effects of various blend compositions and two mixing methods on morphological and rheological behavior of the blends were studied. Scanning electron microscope (SEM) was used to investigate morphology behavior of the blends. The rheological studies illustrated that all samples presented shear thinning behavior and the PLA-rich blends exhibited a Newtonian region. It was found from the rheological measurements that the LLDPE/PLA (75/25 w/w) prepared by batch mixer exhibited higher values of storage modulus and complex viscosity, which is in agreement with the morphology results. In addition, using the different mixing methods, significant differences in the morphological results for the LLDPE/PLA (50/50 w/w) blend were observed. Finally, the results showed that the blends prepared by batch mixer exhibited better morphology, higher storage modulus, and complex viscosity.

Cite this publication as follows:
Maryam H, Ali H, Navid F: Influence on compounding methods on rheology and morphology of linear low density polyethylene/poly(lactic acid), Appl. Rheol. 26 (2016) 64746.

Gholamhossein Sodeifian, Ali Haghtalab
Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends

Appl. Rheol. 14:4 (2004) 180-189

Frequency sweep experiments were performed on poly(vinyl chloride) (PVC) and acrylonitrile butadiene rubber (NBR) as well as their miscible blends PVC/NBR (70/30), PVC/NBR (50/50), and PVC/NBR (30/70) in oscillatory shear. The samples were prepared by mechanical blending at 160.C. In order to investigate the validity of time temperature superposition (TTS) principle the loss angle d versus the logarithm of the absolute value of the complex modulus, G*, were plotted. It was shown that the TTS principle is not valid for the above-mentioned polymer materials and therefore they are not thermorheologically simple. Master curves of PVC, NBR, and PVC/NBR (50/50) blend were therefore obtained approximately. Using a nonlinear regression method, discrete relaxation spectra were determined for PVC, NBR, and PVC/NBR (50/50). To study non-linear viscoelasticity behavior, the experiments of steady shear, start up steady shear, and step strain were carried out. The damping function was determined by the step strain experiments. Using K-BKZ constitutive equation, the shear viscosity and the shear stress growth function were calculated from the discrete relaxation spectra and the damping function and then compared to experimental data. The K-BKZ constitutive equation provides very good prediction over the entire range of experimental results.

Cite this publication as follows:
Sodeifian G, Haghtalab A: Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends, Appl. Rheol. 14 (2004) 180.


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