Morphology Of Polymer Blends Research Articles

The Effect of Polyurethane Grafted onto Styrene/Styrenesulphonic Acid Copolymer on the Morphology of various Polymer Blends

The Effect of Polyurethane Grafted onto Styrene/Styrenesulphonic Acid Copolymer on the Morphology of various Polymer Blends

Study on PET/PP microfibrillar composites. I. Morphological development in melt extrusion

AbstractPoly(ethylene terephthalate)/polypropylene (PET/PP) blends of different compositions were extruded through a 2‐mm capillary die using a corotating twin‐screw extruder. The extrudates were cryogenically fractured and examined using scanning electron microscopy. The viscosity ratio of the constituent polymers alone was found not suitable for explaining the polymer blend morphology. At a PET concentration of 20%, the extrudate consists of three regions: The skin layer, about 10 μm thick, has a lower concentration of the dispersed PET phase than that of the overall concentration. The intermediate region, about 400 μm thick, has profuse PET fibers and some small PET particles. The central region, approximately 800 μm in diameter, contains mainly PET particles that are generally bigger. A low barrel temperature, low die temperature, and fast cooling rate helped to retain the fibers near the extrudate skin. Meanwhile, variation of the barrel temperature, die temperature, and cooling media did not affect the PET particle‐size distribution significantly in the central region of the extrudate. A high screw speed and a high postextrusion drawing speed were very effective in producing fibers in the extrudates through elongation of the particles. At a PET concentration of 30%, coalescence of the PET phase was prevalent, leading to the formation of PET platelets near the extrudate skin and irregular PET networks in the central region of the extrudate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3100–3109, 2003

Phase separation of polyaniline blends with thermoplastic polymers

The conducting complex PANI-CSA and copolyamide (CPA) blended by casting their solutions and the ternary polymer blends PANI-CSA/CPA/LDPE were prepared via blend of PANI-CSA/CPA and LDPE in a twin-screw at 160 °C. PANI-CSA/PMMA/LDPE was also prepared. The morphology and phase separation of the ternary polymer blends were investigated by means of TEM and DSC. The components of the polymer blends were found to be incompatible and phase separation occurred.

Hierarchic Structure Formation in Binary and Ternary Polymer Blends

The phase morphology of multi-component polymer blends is governed by the interfacial interactions of its components. We discuss here the domain morphology in thin films of model binary and ternary polymer blends containing polystyrene, poly(methyl metacrylate), and poly(2-vinylpyridine) (PS, PMMA, PVP). When sandwiched between two non-polar surfaces, characteristic lateral phase morphologies are observed after the film formation by spin-coating. We discuss here two techniques, by which hierarchical lateral structures in polymer films can be made. The first method makes use of two simultaneously occurring interfacial instabilities. The second technique employs the effect of a variation of the enthalpic interaction parameters in a ternary polymer mixture on its lateral polymer phase morphology.

Morphology and Mechanical Properties in Polymer Blends of Photocurable Polymer and Polycarbonate

AbstractRelationships between the morphologies and mechanical properties of binary blends of a photocurable polymer (2‐propenoic acid, (octahydro‐4,7‐methano‐1H‐indenediyl) bis(methylene)ester; DCA) and a linear polymer (poly(4,4′‐cyclohexylidene bisphenol carbonate); PCz) have been investigated. The blend films are prepared by in situ photopolymerization of homogeneous mixtures of a DCA‐monomer and PCz. The phase structure has been converted from a semi‐interpenetrating polymer networks (semi‐IPN) structure to a bicontinuous structure by controlling the cure temperature. Bicontinuous phase‐separated structures can be obtained by curing a wide range of compositions of 17–50 wt.‐% PCz at high temperatures. Miscible semi‐IPN structures are attained by means of photopolymerization below the glass transition temperature of the homogenous mixture before performing photoirradiation, such that magnetic relaxation measurements showed the blend to be miscible in the 10 nm order. The tensile strength and modulus reached a maximum in those blends having an intermediate vague phase structure between semi‐IPN and bicontinuous structures that have a strong interfacial interaction, which leads to incomplete phase decomposition in the PCz‐rich matrix phase. The maximum strength and modulus prepared under optimum condition are inferior to those of the individual components. In contrast, the elongation and break energy are greatly improved in those blends with bicontinuous structures having a diffused phase boundary. DCA‐rich domain size in bicontinuous structure for DCA/PCz system, as a function of cure temperature; (□) 17 wt.‐% PCz, (○) 30 wt.‐% PCz, and (⋄) 50 wt.‐% PCz.magnified imageDCA‐rich domain size in bicontinuous structure for DCA/PCz system, as a function of cure temperature; (□) 17 wt.‐% PCz, (○) 30 wt.‐% PCz, and (⋄) 50 wt.‐% PCz.

Comparação entre duas teorias para a determinação da tensão interfacial pelo método de fibra quebrante

A tensão interfacial entre polímeros fundidos é um fator chave para a predição da morfologia de blendas poliméricas. Neste trabalho, as teorias de Tomotika e Tjahjadi et al. para medir tensão interfacial entre polímeros fundidos usando o método de fibra quebrante são avaliadas e comparadas. Em particular, foram testadas ambas as teorias para o par de polímeros PP/PS à temperatura de 200 °C. O valor médio de tensão interfacial calculado usando a teoria de Tomotika foi de 5,88 mN/m, e usando a teoria de Tjahjadi et al. foi de 5,66 mN/m.

Online Light Scattering Measurements as a Means to Assess Influence of Extrusion Parameters on Non‐reactive Polymer Blend Morphology: Experimental Procedure and Preliminary Results

AbstractThe influence of extrusion parameters on the morphology of non‐reactive blends has been investigated by means of online light‐scattering measurements. A light‐scattering device was especially designed to be mounted on a twin screw extruder at different locations along the barrel. The obtained light‐scattering patterns were interpreted with respect to the variation of the processing parameters. Preliminary results show that there is little effect of the rotational speed, position along the screw and feed throughput on the morphology but a quite noticeable effect of the blend composition. These results were confirmed by SEM micrographs.

Morphology in Immiscible Polymer Blends During Solidification of an Amorphous Dispersed Phase under Shearing

AbstractSolidification under shear of dispersed polycarbonate (PC) fibers in copolymer polyethylene‐methyl acrylate matrix (EMA) was investigated using a hot optical shear device. First, the deformation of PC droplets and its modeling under isothermal conditions were studied for comprehension purposes. Overall agreement with literature models was found and the main influence of the viscosity ratio has been stressed. Second, the morphology control through dynamic quenching was experimented. It consists of solidifying the amorphous PC dispersed phase under shear flow. Break‐up times of PC fibers were taken into account. Shear rate and quenching‐time balance was demonstrated. Thus, during dynamic solidification, a fibrillar morphology could be obtained through rapid quenching. Long quenching times allow nodular morphology, whose size depends on the shear rate used. PC rods can be obtained by adjusting the shear rate during dynamic quenching.

Badania polimerow z wykorzystaniem metody mikroskopii sil atomowych (AFM). Cz. I. Podstawy AFM i jej zastosowanie w badaniach morfologii polimerow

On the basis of recent literature data the principles of Atomic Force Microscopy (AFM) and progress in the development of this technique have been reported. Its advantages and shortcomings as well as the possibilities it creates have also been discussed. Application of AFM method for geometric structure of polymer surface determining as well as determining of surface roughness and morphology of polymer blends and copolymers. AFM is especially useful for investigation of the surface defects, impurities, wettability, polymer miscibility, phase separation, selforganized structures and molecular interactions. Owing to AFM the influence of polymer surface morphology on the polymer properties (in nanometer scale) can be estimated.

Wplyw poliuretanu szczepionego na kopolimerze styren/kwas styrenosulfonowy na morfologie roznych typow mieszanin polimerowych

Wplyw poliuretanu szczepionego na kopolimerze styren/kwas styrenosulfonowy na morfologie roznych typow mieszanin polimerowych

Target morphologies via a two-step dissolution-quench process in polymer blends.

A novel process for obtaining controlled morphologies in polymer blends is modeled numerically. Particles of one type of polymer are allowed to dissolve in a matrix of a dissimilar polymer. Prior to complete dissolution the blend is quenched into the two-phase region, such that phase separation takes place. The combination of the incomplete dissolution and the wavelength selection process associated with phase separation results in particles that during the "intermediate" stages have a core that is significantly richer in the matrix material.

Online light scattering measurements: A method to assess morphology development of polymer blends in a twin‐screw extruder

AbstractLight scattering has proved itself an efficient technique to determine particle diameters in heterogeneous dilute dispersions in the micrometer range. Extrusion of polymer blends is expected to give rise to very small particles, typically in the range from hundreds of nanometers to tens of micrometers. A light scattering device developed in our laboratory has been used to study the morphology of polymer blends obtained in a twin‐screw extruder. The main advantage of this technique is the immediate response obtained without any surface or interface modification that can occur during the sample preparation by using more conventional techniques like electron microscopy. To show the possible applications of this light scattering device, preliminary tests have been carried out. First, we present a comparison between experimental measurements and theoretical results for dilute systems. Second, we have investigated the effect of shear flow on the droplet deformation. Finally, we have studied the variations of the light scattering pattern for a reactive blend.

Morphology and mechanical properties of polymer blends with photochemical reaction for photocurable/linear polymers

The relationship between morphology and mechanical properties were investigated in a binary blend of photocurable polymer (2,2-bis(4-(acryloxy diethoxy)phenyl)propane; BPE4) and linear polymer (polysulfone; PSU). The blend films are prepared by in situ photopolymerization of homogeneous mixtures of BPE4-monomer and PSU. The tensile strength and modulus reach a maximum in the blends having vague domain structures with a diffusion-phase boundary, at which the underdeveloped small BPE4-rich domains are wrapped with the PSU-rich matrix. The higher strength and modulus are caused by a strong interfacial adhesion between the BPE4-rich domain and the PSU-rich phase, which is brought about by incomplete phase separation in the PSU-rich phase. The tensile strength and modulus decrease as the bicontinuous structures clear due to deterioration of the interfacial adhesion. The mechanical properties also deteriorate in the blends with semi-IPN structures due to the lower conversion of BPE4. The composition dependencies on the tensile strength and the modulus for blends cured at optimum cure temperatures were found to give convex curves reaching maximums greater than those of pure components.

Effect of a reactive interfacial agent on the properties of a nitrile-rubber-modified epoxy film adhesive

Reactive interfacial agents are often used to homogenise the morphology of immiscible polymer blends and to improve the level of adhesion between the phases to achieve enhanced properties. This paper demonstrates the ability of hydroxyl methyl bisphenol A (HMBPA) to function as a reactive interfacial agent (compartibilizer) in a nitrile-epoxy film adhesive made from nitrile rubber (NBR) and solid epoxy resin blend. The curing of the adhesive film was achieved at 170° C by adding dicyandiamide, a latent curing agent for epoxy resin, and rubber vulcanising agents. Hydroxyl methyl bisphenol A resins with different hydroxyl methyl content, synthesised by the base-catalysed reaction of bisphenol A and formaldehyde in various mole ratios, were used to compatibilize a blend of nitrile rubber (NBR) and epoxy resin 50/50wt/wt. The effect of addition of HMBPA on the morphology, adhesive, thermal, and mechanical properties of the adhesive film was investigated. The nitrile-epoxy adhesive films were characterised by measurements of adhesive joint strength, stress-strain properties, DSC, TGA, TMA, DMA, and SEM. Results revealed that significant improvement in joint strength occurred at low levels of HMBPA, and the optimum strength was obtained at about 15 wt% of HMBPA in the blend. The hydroxyl methyl content in HMBPA was found to influence the properties of the adhesive film. The concept of strengthening the interphase between NBR and epoxy through the coupling reactions of HMBPA was used for interpreting the results. The effect of addition of silica, alumina, and aluminium fillers on the properties of the nitrile-epoxy adhesive film was also studied, and a comparison of properties with and without HMBPA is presented.

Anisotropic ordering in sheared binary fluids with viscous asymmetry: Experiment and computer simulation

Optical measurements of the structure and morphology of phase-separating polymer blend under simple shear flow have been performed and the results are compared with computer simulations of sheared phase-separating binary mixtures with viscous asymmetry in the fluid components. Information about the structure is obtained from the two-point composition correlation function. Both experiment and simulation suggest subtle differences in the shear response depending on whether the more viscous phase is dispersed or continuous. Measurements of the string width along the neutral direction suggest power-law decay in the shear rate with an exponent of 1/3 when the more viscous phase is dispersed. The simulations suggest that the mean string width, measured along the velocity-gradient direction in the two-dimensional model calculation, exhibits power-law decay in the shear rate with an exponent of 1/3 independent of which phase is dispersed.

A study on weld line morphology and mechanical strength of injection molded polystyrene/poly(methyl methacrylate) blends

AbstractIn this work, the mechanical strength and weld line morphology of injection molded polystyrene/poly(methyl methacrylate) (PS/PMMA) blends were investigated by scanning electron microscopy (SEM) and mechanical property test. The experimental results show that the tensile strength of PS/PMMA blends get greatly decreased due to the presence of the weld line. Although the tensile strength without the weld line of PS/PMMA (70/30) is much higher than that of the PS/PMMA (30/70) blend, their tensile strength with weld line shows reversed change. The viscosity ratio of dispersed phase over matrix is a very important parameter for control of weld‐line morphology of the immiscible polymer blend. In PS/PMMA (70/30) blend, the PMMA dispersed domains at the core of the weld line are spherically shaped, which is the same as bulk. While in the PS/PMMA (30/70) blend, the viscosity of the dispersed PS phase is lower than that of the PMMA matrix, the PS phase is absent at the weld line, and PS particles are highly oriented parallel to the weld line, which is a stress concentrator. This is why weld line strength of PS/PMMA (30/70) is lower than that of PS/PMMA (70/30) blend. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1856–1865, 2002; DOI 10.1002/app.10450

The Role of the Blend Interface Type on Morphology in Cocontinuous Polymer Blends

Three different categories of blend interfaces are examined systematically in order to isolate the role of the interface in the development of cocontinuous morphologies during melt mixing. They are Type I, compatible binary blends based on high-density polyethylene (HDPE)/styrene−ethylene−butylene−styrene (SEBS) and HDPE/styrene−ethylene−butylene (SEB); Type II, an incompatible binary system comprised of HDPE/polystyrene (PS); and Type III, compatible ternary systems comprised of HDPE/PS compatibilized by SEBS in one case and by SEB in another. The Type I and Type III systems represent conventional approaches to preparing blend systems of low interfacial tension. The cocontinuous morphology is analyzed using three techniques: microscopy/image analysis, solvent extraction/gravimetric analysis, and BET characterization of surface area and pore size. A mechanism for the formation of dual-phase continuity based on droplet and fiber lifetimes during melt mixing has been proposed. For the Type I compatible bin...

Photopolymerization-induced phase separation in binary blends of photocurable/linear polymers

Phase separation behavior and morphology of polymer blends induced by photopolymerization have been investigated in a binary blend of photocurable polymer (2,2-bis(4-(acryloxy diethoxy)phenyl)propane; BPE4) and linear polymer (polysulfone; PSU) using electron microscopy techniques. A ternary phase diagram of mono-BPE4/poly-BPE4/PSU exhibits a lower critical solution temperature (LCST) behavior. In situ polymerization of BPE4 over a wide range of PSU compositions (5–70 wt%) results in network-like bicontinuous phase separated structures at high temperatures, while semi-interpenetrating polymer network (IPN) structures are cured at low temperatures. Even at 10 wt% PSU, the PSU-rich phase is a continuous network-like phase. BPE4-rich domains in the network-like structures are controlled from the nano-scale (30 nm) to the microscale (1 μm) by varying the composition, curing temperature and irradiation intensity. By means of time-evolution study of the phase structure, it is found that BPE4-rich domains appeared in a PSU-rich matrix after the induction time. These domains quickly grow in size up to the sub-micron level, but further growth appears to be slow. The PSU-rich matrix develops into the network-like pattern by the increase in the number and growth of the BPE4-rich domains.

Dual-phase continuity and phase inversion in polycarbonate/polystyrene blends during compounding

Dual-phase continuity is a special case of morphologies in binary polymer blends where both phases maintain their whole continuity. Since this morphology can affect many physical and mechanical properties including impact strengh, elongational properties, and permeability characteristics [1–3], it is of great importance to know how these complicated morphologies are formed in situ and can be controlled during processing. However, the complexity of the microstructure brings about difficulties for its characterization and description. Until now, a few studies have been conducted in this area [4–6], but co-phase continuity remains one of the poorly understood phenomena in polymer blends during compounding. The nature of co-continuity and phase inversion after melt blending or after re-melt blending in twin-screw extruders has not been fully described. The effect of polymer/polymer blending in injection molding machines on the morphology is also unknown. In this study, the morphology of polycarbonate (PC) and polystyrene (PS) blends during compounding both in a twin-screw extruder and in an injection molding machine and the validity of the theoretical model in predication of the point of phase inversion were investigated in the composition range. A semi-empirical expression for predicting the point of phase inversion based on torque ratio has been proposed by Avgeropoulos et al. [7] expressed as:

Monitoring the Evolution of Morphology of Polymer Blends Upon Manufacturing of Microfibrillar Reinforced Composites

Microfibrillar reinforced composites (MFC) based on HDPE/PET blends were prepared under conditions relevant for direct scale-up to an industrial process. The evolution of the morphology and of the linear viscoelastic response of the blend along the axis of a co-rotating twin screw extruder and at several locations along the extrusion line was monitored. Major changes in the average particle size and size distribution of the disperse phase occurred upon melting of the components, whilst a much slower evolution rate was evident downstream in the extruder. Simultaneously, G′ and G″ increased along the extruder. Pellets showing well oriented PET fibrils embedded in a HDPE matrix with poor adhesion between both were obtained. This MFC showed the typical improvement expected in mechanical performance when compared with the matrix.