Analysis of the morphology of polymer blends using ultrasound (original) (raw)
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Ultrasonic, refractometric, and viscosity studies of some polymer blends in solution
Journal of Applied Polymer Science, 1998
Miscibility studies of poly(vinyl pyrrolidone)-polystyrene and poly(vinyl pyrrolidone)-poly(methyl methacrylate) in mixed common solvent (dimethyl formamide ϩ cyclohexanone) have been carried out in different percentages of the blend components. The ultrasonic velocity, viscosity, density, and refractive index have been measured at 30°C. The interaction parameters have been obtained using the viscosity data to probe the miscibility. The obtained results have been confirmed by the ultrasonic velocity, density, and refractive index.
Licensed Under Creative Commons Attribution CC BY Ultrasonic Investigation of Solution Blends of
2015
Abstract: The present investigations deal with the study of ultrasonic velocity and related thermoacoustical parameters of Polybutadiene(PB) –Polymethyl Methacrylate(PMMA) blends. Ultrasonic velocity, density, measurements have been performed on solution blends of PB-PMMA in various blend ratios using THF as solvent. These measurements have been observed to deviate from linearity with variations in blend ratio. The ultrasonic velocity and density of solution blends are significantly depend on temperature and solid content of blend solution. Ultrasonic velocity, density measurements are done at 2MHz frequency and for temperatures 293K,
Ultrasonic investigation of PDMS/PIB blends in a wide range of concentrations
Polydimethylsiloxane/polyisobutylene blends are investigated using ultrasonic techniques ͑megahertz range͒, in the complete concentration range ͑0%-100%͒. The velocities of propagation and attenuations of shear and longitudinal waves are determined experimentally together with simultaneous optical microscopy observations. From the knowledge of the acoustical and physical properties of the separate polymers, the acoustical longitudinal parameters of the blend can be predicted successfully up to 40% volume concentration of the dispersed phase, with a model developed by the authors and especially adapted to wave propagation in such viscoelastic emulsions. For shear waves, two emulsion models ͑Palierne and Lee-Park͒ are used for predicting the viscoelastic moduli associated with the acoustical data at ultrasonic frequencies, with a good agreement. The case of composite droplets ͑40%-60%͒ has required to consider Friedrich's extension of Palierne's model. The ultrasonic method appears to be a very interesting tool for predicting phase inversion for polymer blends, as well as the evolution of the microstructure of the blend. Finally, this work provides an extension of the validity of emulsion models in the high frequency range.
Influence of composition and morphology on rheological properties of polyethylene/polyamide blends
Polymer, 1998
The effects of composition and resulting morphology on rheology of blends of polyethylene and polyamide 12, two immiscible polymers having the same Newtonian viscosity but different elasticity, were studied in the whole range of volume fraction. The composition dependence of zero shear rate viscosity ~/0 and first normal stress difference N~ show a positive deviation from the additivity law: ~/0 and Nt increase gradually at low and moderate volume fraction of the dispersed phase, but remain almost constant in the phase inversion region. The variation of zero shear rate viscosity has been analysed, in relation to morphology observations, by an emulsion model as developed by Oldroyd in the case of droplet-type morphology and by a layer model which takes into account the simultaneous presence of droplets and fibres when the morphology is partially fibrillar. If the volume fraction of the dispersed phase is not too low, the first normal stress difference is proportional to shear rate, in agreement with the prediction of Doi-Ohta theory, as a result of morphology modifications during flow. The linear viscoelastic behaviour has been analysed using Palierne's model and the interfacial tension between the two polymers has been determined by fitting the dynamic moduli with this model.
European Polymer Journal, 2016
The morphology of immiscible 80/20 polypropylene/polyamide 6 (PP/PA) blends that contain different types of nanosilica and a compatibilizer agent was correlated with their linear and non-linear rheological behavior. Polypropylene grafted with maleic anhydride (PPgMA) was used as compatibilizer agent. Two types of modified silica nanoparticles were added to the blends, one hydrophilic (NSE) and the other hydrophobic (NSH). SEM and TEM microscopy were employed to observe the sea-island morphology of the 80/20 blends. The size of the PA droplets was reduced 12 times when the compatibilizer agent was added; and 25 times when hydrophobic nanosilica (NSH) was additionally included in the formulation. TEM results revealed that NSH particles are preferentially located at the PP-PA interface, whereas NSE particles remain inside the PA droplets. A good agreement between morphology and Small Amplitude Oscillatory Shear tests (SAOS) was observed. At low frequencies a suspension-like rheological behavior was identified for the blends containing nanosilica. The results at intermediate frequencies allowed the evaluation of the shape relaxation time of the droplets. Large Amplitude Oscillatory Shear tests (LAOS) results correlate well with droplets size. The coalescence promoted by flow was investigated, and in the case of the neat binary blend, coalesced blends were obtained. Employing LAOS results determined by measuring blends with a wide range of droplet sizes, an inversely proportional function of a characteristic LAOS parameter with the diameter of the droplets was obtained.
The compatibility of solid blends: PS/SBR, PS/SBR filled with glass fiber and PS/SBR filled with talc were studied using ultrasonic pulse echo technique. Measurements were carried out at room temperature (298 K) and a frequency of 3 MHz. The ultrasonic velocity for the compressional wave and that for shear wave have been measured to obtain the elastic moduli data by knowing of density. The variation of ultrasonic wave velocities and elastic moduli with weight percent of the blend was found to be linear in PS/SBR blend, indicating some degree of compatibility but the drawback of elastic moduli indicate incompatibility of the system blend, while it deviates from linearity in blends of PS/SBR filled with glass fiber and talc but the increase in elastic moduli indicates that there is an increase in degree of compatibility between PS and SBR due to adding of glass fiber or talc. The ultrasonic absorptions for longitudinal wave in the temperature range from 298 to 423 K in the studied system were measured using ultrasonic pulse echo technique. Typical results showing the temperature dependence of the ultrasonic absorption at frequencies of 1, 2, 3 and 5 MHz are illustrated for all samples of the different compositions. The study of compositional and temperature dependence of the ultrasonic absorption in the present studied blends reveals the same behavior of the compatibility degree of the blends. Density data of the blends confirmed the ultrasonic results. Also the correlation between hardness and elastic moduli for the present blend systems has been studied.
Effect of Composition on the Rheological Properties of (PC/ABS) and (PVDF/LDPE) Blends
A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) and another series of polyvinylidene fluoride, PVDF, and low density polyethylene, LDPE, were prepared and characterized for some of their rheological properties. The blends of a series were prepared by mixing the components, with different weight % composition, in a molten state using Brabender Plastograph. Visco-elastic parameters were measured using the capillary rheometer (Melt Index 3/80). Die-swelling rate, (B), was determined for different composition samples and correlated with the end pressure drop, (Pend), the end correction, (e), the apparent shear rate, (a), the apparent shear stress, (a), and the length-radius ratio, (L/R). The effects of blending composition on the die-swell rate, (B), the end correction, (e), and the shear strain, (SR) were also studied for the prepared series of blends.