Here, the effect of concentration on the morphology and dynamic behavior of polymethylmethacrylate/polystyrene (PMMA/PS), for PS with two different molecular weight, and polymethylmethacrylate/polypropylene (PMMA/PP) blends was studied. The blends concentrations ranged from 5% to 30% of the dispersed phase (PS or PP). The dynamic data were analyzed to study the possibility of inferring the interfacial tension between the components of the blend from their rheological behavior using Palierne [Palierne JF. Rheol Acta 1990;29:204-14] [1] and Bousmina [Bousmina M. Acta 1999;38:73-83] [2] emulsion models. The relaxation spectrum of the blends was also studied. The dynamic behavior of 85/15 PS/PMMA blend were studied as a function of temperature. It was possible to fit both Palierne and Bousmina's emulsion models to the dynamic data of PMMA/PS blends, to obtain the interfacial tension of the blend. This was not the case for PMMA/PP. The relaxation spectrum of both blends was used to obtain the interfacial tension between the components of the blends. The values of interfacial tension calculated were shown to decrease when the concentration of the blends increased. It was shown using morphological analysis that this phenomenon can be attributed to the coalescence of the dispersed phase during dynamic measurements that occurs for large dispersed phase concentration. When the ‘coalesced’ morphology is taken into account in the calculations the interfacial tension inferred from rheological measurement did not depend on the concentration of the blend used. The values of interfacial tension found analyzing the dynamic behavior of one of the PMMA/PS blend were shown to decrease with temperature. 相似文献
Correlation between the rheology and morphology of PVDF/LLDPE blends as well as the effect of LLDPE-g-MA compatibilizer on the microstructure and viscoelastic properties of these blends were studied in detail. Morphology development from matrix-dispersed to co-continuous and again to dispersed-matrix was well predicted using various linear viscoelastic analyses and confirmed via direct SEM experiments and continuity index analysis. Compatibilization induced alteration in the microstructure of the blends, particularly PVDF/PE 50/50 blend from co-continuous morphology to dispersed-matrix one, was also concluded from viscoelastic analysis and confirmed. It was shown that the feeding order had a distinct effect on morphology of the blends near the phase inversion composition. “Phase within a phase within a phase” morphology was observed near the phase inversion region, provided that the components are fed simultaneously. Different melting and crystallization temperature range of PVDF and PE phases was understood to be the main reason of this observation. It was also shown that compatibilization had higher impact on LLDPE-rich blends than PVDF-rich blends, while narrowed the co-continuity composition range.
The phase inversion process was investigated from different points of view. First, a reliable on-line and off-line method of morphology detection using light microscopy is established. The method provides fast information that can be used to discriminate between different types of morphologies. Second, TEM images are modelled with Markov Random Fields. For characterization purposes image features are introduced and tested. A combination of features allows classification of different morphologies of PMMA/PS blends. In the third part we show that the rheological properties of blends allow also discrimination between different morphologies. Received: 6 November 1997/Revised version: 3 December 1997/Accepted: 3 December 1997 相似文献
As a part of long-term project aimed at super polyolefin blends, in this work, we report the mechanical reinforcement and phase morphology of the immiscible blends of polypropylene (PP) and polystyrene (PS) achieved by dynamic packing injection molding (DPIM). The shear stress (achieved by DPIM) and interfacial interaction (obtained by using styrene-butadiene-styrene (SBS) as a compatibilizer) have a great effect on phase morphology thus mechanical properties. The shear-induced morphology with core in the center and oriented zone surrounding the core was observed in the cross-section areas of the samples. The phase inversion was also found to shift towards lower PS content under shear stress, at 70 wt% in the core and 30 wt% in the oriented zone, compared with 80 wt% for static samples (without shear). The tensile strength, tensile modules and impact strength were found largely increase by means of either shear stress or compatibilizer. The PS particle size is greatly reduced with adding of SBS, and the reduced particle size results in greater resistance to deformation, which causes the co-continuous structure at oriented zone change into droplet morphology. The morphology resulting from blending and processing was discussed based on effect of interfacial tension, shear rate, phase viscosity ratio and composition. The observed change of mechanical properties was explained based on the combined effect of phase morphology (droplet-matrix or co-continuous phase) and molecular orientation under shear stress. 相似文献
The tensile properties and morphology of the polyolefin ternary blends of ethylenepropylene–diene terpolymer (EPDM), polypropylene and high density polyethylene were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured in the presence of PP and HDPE under shear with dicumyl peroxide (DCP). For comparison, blends were also prepared from EPDM which was dynamically cured alone and blended with PP and HDPE later (cure–blend). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastics composition was studied. The tensile strength and modulus increased with increasing DCP concentration in the blends of EPDM-rich compositions but decreased with increasing DCP concentration in blends of PP-rich compositions. In the morphological analysis by scanning electron microscopy (SEM), the small amount of EPDM acted as a compatibilizer to HDPE and PP. It was also revealed that the dynamic curing process could reduce the domain size of the crosslinked EPDM phase. When the EPDM forms the matrix, the phase separation effect becomes dominant between the EPDM matrix and PP or HDPE domain due to the crosslinking in the matrix. 相似文献
In this study, influences of both component ratio of minor phases and charge sequence on the morphology and mechanical performance
in typical ternary blends, polypropylene (PP)/polystyrene (PS)/polyamide-6 (PA6), have been studied. Reactive compatibilization
of the blends has been carried out using multi-monomer melt grafted PP with anhydride groups and styrene segments. For uncompatibilized
blends, scanning electron microscope (SEM) and selective solvent extraction showed that the blends presented a core–shell
morphology with PS as shell and PA6 as core in the PP matrix, in spite of the component ratio and charge sequence. The shell
thickened and droplet size decreased with increasing the PS/PA6 component ratio. While for compatibilized blends, the addition
of compatibilizers resulted in a significant reduction of the dispersed droplet size and the phase structure of the dispersed
phases was greatly dependent on the charge sequence. When the blending of PA6, g-PP, and PP are preceded, the encapsulation
structure reversed into the structure of PS phase encapsulated by PA6 phase, which led to better tensile and flexural strength
of the blends. 相似文献
The formation and evolution of the phase morphology of polypropylene (PP) with Nylon1010 (PA1010) blends before and after adding the compatibilizer, polypropylene grafted maleic anhydride (PP-g-MAH), during melt mixing are investigated by the pattern analysis of scanning electron microscope (SEM). The average particle diameter DPAV, characteristic length Λ and the average characteristic length Λm are calculated to discuss the melt mixing process. It is proved, by the figure-estimation theory, that the distribution of Λ is log-normal distribution. Furthermore, the phase morphology during melt mixing is discussed in depth by the parameters of the log-normal distribution. The results demonstrate that the structure of the dispersed phase during melt mixing evolves with dynamical self-similarity through the competition of break-up and coalescence of dispersed phase. A fractal dimension, based on the probability density of the character length, is calculated in this study. The results show that the fractal dimension is an effective parameter to characterize the melt mixing process of polymer blends. 相似文献
(PPE/PS)/PA6 and PS/PA6 blends were prepared by means of melt-extrusion. They were compatibilized using the reactive styrene-maleic anhydride copolymer with 2 wt% maleic anhydride (SMA2). The effect of compatibilization on the phase inversion and the stability of the resulting co-continuous blend structures were investigated using scanning electron microscopy, dissolution and extraction experiments. The onset of co-continuity shifted towards lower PA6 concentrations according to the change in blend viscosity ratio. The melting order of the components inside the extruder could result in a change in the observed co-continuity interval in slowly developing phase morphologies. The unmodified co-continuous blends were not stable and did break-up into a droplet/matrix type of morphology upon annealing in the melt depending on the blend composition. Although the stability of the threads during annealing improved upon compatibilization because of the lower resulting interfacial tension, the decreased possibility for recombination and coalescence during flow reduced the co-continuous region for the compatibilized blends. It is proposed that a dynamic equilibrium between break-up and recombination phenomena after the initial network formation is necessary to maintain the network structure. 相似文献