Rheological properties of polymer blends

The properties of PLA can be modified by polymer blending techniques. PLA has been blended with several synthetic and biopolymers in order to enhance its properties and to obtain novel materials. PLA has been blended with rubbers, thermoplastic starch (TPS), poly(butylene succinate) (PBS), poly(butylenes succinate adipate) (PBSA), poly(butylene 

L/D ratio of 42. About 0.5 wt% (weight ratio to PLA/PBAT) of tris(nonylphenyl) phosphate (TNPP) was used as a stabilizer to eliminate the degradation of PL A in the heating process. TNPP acts as a chain extender, reconnecting polymer chains that have been broken due to moisture and elevated temperature. 

The power-law equation is used to fit the data and it shows a good result where all the equations have a correlation coefficient (r ) greater than 0.99. The calculated values of n for PLA and its blend melts are presented in Table 6.6. The incorporation of PBAT leads to a decrease of flow index n. The temperature dependence of the viscosity of polymer melts is one of the most important parameters in polymer flow. Within a certain range of temperatures, the dependence can be expressed in the Arrhenius form  

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Rameshwaram et al. [6] investigated the structure-property relationships and the effects of a viscosity ratio on the rheological properties of polymer blends using oscillatory and steady shear rheometry and optical microscopy. 

Utracki, L.A. (1989) Polymer Alloys and Blends, Hanser Publishers, Munich. SteDer, R. and Zuchowska, D. (1990) Free volume theory for rheological properties of polymer blends. J. pl. Pdlym. Sci., 41 (7-8), 1595-1607. 

The rheological properties of polymer blends - and especially of thermosetting polymer blends - share a close relationship to the morphology and reactions involved. Moreover, these properties can cause changes in shear or strain conditions that may lead to dramatic variations in the phase structure and other properties of polymer blends. The time-temperature superposition principle (WLF-type equations) and power laws have been widely applied to the linear viscoelastic behavior of both neat polymers and blends, despite the fact that they may reflect different types of structure transitions for either thermoplastic or thermosetting resins. 

Table lovestigations on the Rheological Properties of Polymer Blends... 

Subrhamanian R, Zumbruimen DA. A device for simultaneous in situ structuring and measurement of rheological properties of polymer blends and composites. Proceedings of the 71st annual technical conference. Society of Plastics Engineers 2013. 

The objective of this work is to present a critical review of the recent work on the rheological properties of polymer blends. In particular, we will examine in detail how deformability of the droplets of the minor phase and miscibility of the components affect the rheological properties of blends using experimental data, in light of recent theories. 

Needless to say, the rheological properties of polymer mixtures are complex and nearly impossible to predict. Figure 4.12 shows the viscosity of a natural rubber (NR)/poly(methyl methacrylate) (PMMA) blend (top curve) as a function of percentage NR [2]. For comparison, the predictions of four common equations are shown. The equations are as follows ... 

Basic rheological parameters of polymer blends determined by the properties of the polymer matrix, so the properties of melts are generally defined by PHB. Lower viscosity of the melt blend composition (due to the formation of a continuous matrix PHB) in this case will significantly simplify the processing of the investigated materials. Also, the data in Figure 2.6 are consistent with the position that the greater the difference in viscosity of mixed polymers, the earlier the formation of a continuous matrix less viscous component. 

H.-W. Shen, B.-H. Xie, W. Yang, M.-B. Yang, Thermal and rheological properties of polyethylene blends with bimodal molecular weight distribution. J. Appl. Polym. Sci. 129, 2145-2151 (2013)... 

The orientation of particles in flow is of particular interest to microrheology. To predict the macroscopic rheological properties of a multiphase system, a detailed description of each phase behavior is required. In this field, contributions from the Pulp and Paper Research Institute of Canada by Mason et al. and later by van de Ven and his coauthors are particularly valuable. The earlier results were summarized by Goldsmith and Mason (1967), the latter by Van de Ven (1989). The microrheology has been particularly well developed for infinitely dilute systems in Newtonian matrix - either solid particles or liquid drops. In the present part, only the former system will be summarized. More extensive discussion of microrheology of the liquid-liquid systems will be presented later, while considering the rheological behavior of polymer blends. 

For the NR based blends, therefore, the rheological behaviour must be considered case by case such as blending with thermoplastics and blending with other rubbers. In the case of the chemically modified NR based-blends, it was not only the type of polymer used to blend with NR, but also the variation of the chemical modification of NR would control the different rheological property of the blends. Special-property NR based blends obtained from the... 

Han, C.D. (1971) Measurement of the rheological properties of polymer melts with slit rheometer. I. Homopolymer systems n. Blend systems ni. Two phase systems - higfi impact polystyrene and ABS resins, /. Appl Polym. Set., 15,2567-77,2579-89, 2591-6. 

Dobrescu, V, Influence of blending upon rheological properties of polymers in the melt, in Proc. Vlllth Inti. Congr. on Rheol. (1980), pp. 555-5. ... 

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