Kinetics-controlled compatibilization of immiscible polypropylene/polystyrene blends using nano-SiO2 particles

Rigid inorganic filler has been long time used as a reinforcement agent for polymer materials. Recently, more work is focused on the possibility that using filler as a compatibilizer for immiscible polymer blends. In this article, we reported our efforts on the change of phase morphology and properties of immiscible polypropylene(PP)/polystyrene(PS) blends compatibilized with nano-SiO₂ particles. The effects of filler content and mixing time on the phase morphology, crystallization behavior, rheology, and mechanical properties were investigated by SEM, DSC, ARES and mechanical test. A drastic reduction of PS phase size and a very homogeneous size distribution were observed by introducing nano-SiO₂ particles in the blends at short mixing time. However, at longer mixing time an increase of PS size was seen again, indicating a kinetics-controlled compatibilization. This conclusion was further supported by the unchanged glass transition temperature of PS and by increased viscosity in the blends after adding nano-SiO₂ particles. The compatibilization mechanism of nano-SiO₂ particles in PP/PS blends was proposed based on kinetics consideration.     

Rheological characteristics of synthetic road binders

Most adhesives and binders, including binders for asphalt mixture production, are presently produced from petrochemicals through the refining of crude oil. The fact that crude oil reserves are a finite resource means that in the future it may become necessary to produce these materials from alternative and probably renewable sources. Suitable resources of this kind may include polysaccharides, plant oils and proteins. This paper deals with the synthesis of polymer binders from monomers that could in future be derived from renewable resources. These binders consist of polyethyl acrylate (PEA) of different molecular weight, polymethyl acrylate (PMA) and polybutyl acrylate (PBA), which were synthesised from ethyl acrylate, methyl acrylate and butyl acrylate, respectively, by atom transfer radical polymerization (ATRP). The fundamental rheological properties of these binders were determined by means of a dynamic shear rheometer (DSR) using a combination of temperature and frequency sweeps. The results indicate that PEA has rheological properties similar to that of 100/150 penetration grade bitumen, PMA similar rheological properties to that of 10/20 penetration grade bitumen, while PBA, due to its highly viscous nature and low complex modulus, cannot be used on its own as an asphalt binder. The synthetic binders were also combined with conventional penetration grade bitumen to produce a range of bitumen–synthetic polymer binder blends. These blends were batched by mass in the ratio of 1:1 or 3:1 and subjected to the same DSR rheological testing as the synthetic binders. The blends consisting of a softer bitumen (70/100 pen or 100/150 pen) with a hard synthetic binder (PMA) tended to be more compatible and therefore stable and produced rheological properties that combined the properties of the two components. The synthetic binders and particularly the extended bitumen samples (blends) produced rheological properties that showed similar characteristics to elastomeric SBS PMBs, although their precise viscoelastic properties were not identical.     

Effect of epoxy resin on thermal,dynamic, and mechanical properties of rigid poly(vinyl chloride)

This work is concerned with the effect of an epoxy resin on the properties of rigid poly(vinyl chloride) (PVC). The epoxy resin concentrations of 0, 1, 2, 4, and 6 phr were used to prepare PVC/epoxy polymer blends and the viscoelastic behavior of the blends was investigated by dynamic mechanical thermal analysis and rheometry test. The results revealed that the low molecular weight epoxy resin did not greatly affect the viscoelastic properties of PVC. From the morphological point of view, the smallest droplet size of epoxy dispersed in the polymer blends was found in the sample with 1 phr epoxy resin, and the largest one was for the sample with 6 phr epoxy. The thermal properties of PVC/epoxy blends were investigated using differential scanning calorimetry and thermogravimetric analysis, as well. According to our research, the initial decomposition temperature of PVC was increased about 6°C by the incorporation of epoxy resin. The results of tensile test showed that the addition of epoxy resin decreased the elongation‐at‐break of PVC about 50% in the samples without calcium carbonate and about 25% in the samples containing calcium carbonate. Moreover, the failure mode of PVC was changed from a ductile fracture mode to a brittle fracture mode with the addition of epoxy resin. J. VINYL ADDIT. TECHNOL., 25:E72–E79, 2019. © 2018 Society of Plastics Engineers     

Molecular dynamics simulation and experimental study of the bonding properties of polymer binders in 3D powder printed hydroxyapatite bioceramic bone scaffolds

Binder properties are a key factor affecting the quality of bone scaffolds produced using 3D powder printing. In this research, molecular dynamics simulation (MD) and experimental methods were applied to study the cohesive energy density, mechanical properties, bonding behavior, and surface morphology of three polymer binders (PVP, PAM, PVA) employed in the 3D fabrication of hydroxyapatite (HA) bone scaffolds. The bonding mechanisms of the three polymer binders were revealed by analyzing the interaction between the binders and the HA surface. The binding energies between the binders and HA are associated with the cohesive energy density and viscosity of each of the binders, which are attributed to functional groups in the binders. The mechanical properties determined experimentally for the bone scaffolds produced using each of the three polymer binders were in a different relative order than the engineering modulus of the binders and the interaction between the binders and HA calculated in simulations. This is a reflection of the mechanical properties of bone scaffolds being a comprehensive reflection of the basic materials and their bonding effect. Finally, SEM imaging indicated additional factors affecting the mechanical properties and degradation rate of the scaffolds. Conclusions from this work can be used to forecast the properties of three commonly used polymer binders and provide a theoretical basis for the choice of binders in the production of 3DP-fabricated bone scaffolds.     

Thermal and viscoelastic behavior of polyurethane/polyvinylchloride blends

The potential of melt processing polymer blends to prepare damping materials was investigated. Binary and ternary blends of polyvinylchloride (PVC) with thermoplastic polyurethane elastomers (TPU) were studied. The soft segments of the polyurethanes for the first series were of the ether type and of the ester type for the second series of blends. A series of polymer blends were prepared by mechanical melt mixing and the apparent miscibility was evaluated from the thermal, dielectric, and dynamic mechanical behavior as well as from transmission electron microscopy. Some samples exhibited a single damping peak at low PVC content, indicating miscibility of the blends at the detection scale of the test method. The relationship between the properties and the morphology of the blends was studied.     

Polyaniline Hydrochloride for a Novel Application: Accelerator and Filler for Phenol-Formaldehyde Resin

Abstract

In this work, a study has been made of a novel application of polyaniline hydrochloride (PAn.HCl) in the field of adhesives. Different concentrations of PAn.HCl (0%, 3%, 8%, 13%, 15%, 25%, 35%, 45% and 55% w/w) were blended with phenol formaldehyde resin (resole) by mechanical mixing and the effect of the blending on the adhesive strength and gel time of resin solution was studied. It was discovered that PAn.HCl had an accelerating effect upon the curing of the resin and the curing time was found to be significantly reduced. It was also discovered that PAn.HCl can play a role as a filler in phenolic resin polymer matrices, resulting in an improvement in the mechanical properties (adhesive strength) of the prepared resins. Resole and its blends with PAn.HCl were characterized in terms of their structure, by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The room temperature d.c. electrical conductivities of resole and resole/PAn.HCl blends were studied by the conventional four-point probe method.     

Effect of processing variables on the linear viscoelastic properties of SBS‐oil blends

Block copolymers, especially styrene‐butadiene‐styrene three‐block copolymers (SBS), are recognized as especially effective asphalt modifiers because of their thermoplastic elastomeric properties. The concentration of copolymer, its ability to swell by the maltenic oils, and the processing variables are essential in the development of a three‐dimensional network in the polymer‐rich phase that enhances the vis‐coelastic properties of these modified binders. This swollen polymer phase may influence the mechanical properties of the modified bitumens and synthetic binders. This paper deals with the influences that processing variables exert on the linear viscoelastic properties of oil/SBS mixtures in a wide range of temperatures. From the experimental results obtained we may conclude that most of the oil/SBS blends studied are highly structured thermoplastic gels above a critical SBS concentration that depends upon temperature, time of processing and surrounding atmosphere.     

Study of polycarbonate–polystyrene interfaces using scanning transmission electron microscopy spectrum imaging (STEM-SI)

Polymer blends are important for both commercial utility and scientific understanding. The degree of interfacial mixing in polymer blends is important since it influences the blends' mechanical properties. Understanding bulk properties in multiphase polymeric materials requires knowledge of the interfacial properties of the materials. The characterization of the interface, in terms of its width and composition profile, provides insight about the bulk behaviour of the material. Chemical microscopy through electron energy-loss spectroscopy (EELS) in a transmission electron microscope is gaining popularity to characterize narrow polymer–polymer interfaces. In this work, we show how scanning transmission electron microscopy spectrum imaging, a spatially resolved energy-loss spectroscopy, can be employed to calculate the interfacial width in a pair of immiscible polymers, taking a polycarbonate–polystyrene (PC-PS) bilayer as an example. By mapping peaks unique to each of the blend constituents at several points across the interface, we show how the interfacial profile concentrations can be determined. With this method we calculated the interfacial width in the PC-PS bilayer sample to be approximately 32 nm, even utilizing low resolution spectrometers, which are more widely available. Using the technique described with higher resolution EELS instruments having a better signal-to-noise ratio, a higher spatial resolution can be achieved. Using EELS chemical fingerprints of polymers that have been developed earlier, the technique presented here has the potential for effective visualization and morphological measurements of phase-differentiated polymer blends. This paper is an attempt to enable a new user to characterize polymer–polymer interfaces using chemical microscopy. © 2022 Society of Industrial Chemistry.     

Mechanical properties and failure mode of thermoplastic elastomers from natural rubber/poly(methyl methacrylate)/natural rubber-g-poly(methyl methacrylate) blends

The mechanical properties and fracture behavior of natural rubber/poly-(methyl methacrylate) blends were investigated as a function of composition, graft copolymer concentration, and mixing conditions. The mechanical properties and failure behavior vary with the blend ratio, graft copolymer concentration, and mixing conditions. Various two-phase models were used to fit the experimental mechanical properties. Mechanical properties such as stress–strain behavior, tensile strength, tensile modulus, tear strength, and Izod impact strength were evaluated as a function of compatibilizer concentration. The domain size of the dispersed phase decreases with graft copolymer concentration followed by a leveling off at higher concentration. The mechanical properties attain a maximum value at the leveling point, which is an indication of interfacial saturation and the attainment of maximum interfacial adhesion between the homopolymers. Tensile and tear fracture surfaces were examined by scanning electron microscopy. The detachment of the dispersed domains from the matrix is an indication of no adhesion between the two phases in the case of uncompatibilized blends. Microfibrils between the matrix and the dispersed phase indicate a sign of interfacial adhesion between the phases in the case of compatibilized blends. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:1245–1255, 1997     

Deformation and fracture of polystyrene/polypropylene blends: A simulation study

The mechanical behavior of binary polymer blends polystyrene/polypropylene were studied by a continuous mesoscopic simulation method. The dynamic density functional theory approach embodied in MesoDyn method was adopted to obtain the meso-structures of polymer blends. The output of MesoDyn serves as the input of a micromechanical lattice spring model (LSM), which consists of a three-dimensional network of springs. Mechanical properties, such as young’s modulus and stress distribution can be obtained through applying strain in LSM. Subsequently, a stress-related probabilistic method was applied in LSM to study the fracturing process of materials. The fracture positions were shown in detail which have close relationship with the meso-structures. Due to the significance of interface which has a notable influence on the global mechanical properties of immiscible blends, we proposed a new method to define the stiffness in the interfacial area to study the global stiffness (young’s modulus) of materials. The results show a good agreement with the existing experiments. Besides, we varied the minimum fracture stress (related to toughness) of the interface to investigate the strength of polymer blends. A graphic representation was shown in this work, it indicates that the system with continuous interface perpendicular to the applied strain are more likely to exhibit catastrophic failure. The methods developed in this work provide important tools to predict the mechanical properties of real polymer blends.     

Dynamic–Mechanical Properties of Bioartificial Polymeric Materials

Bioartificial polymeric materials represent a new class of polymeric materials based on blends of synthetic and natural polymers, designed with the purpose of producing new materials with enhanced properties with respect to the single components. The mechanical properties of bioartificial materials prepared using poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as synthetic components, and collagen (SC), gelatin, starch, hyaluronic acid (HA) and dextran as biological components, were investigated by dynamic mechanical thermal analysis. The materials were prepared in the form of films or hydrogels and treated by glutaraldehyde (GTA) vapour or thermal dehydration in order to reduce their solubility in water. The results indicate that SC/PVA, gelatin/PVA and starch/PVA films behave as biphasic systems, showing good mechanical properties over a wide range of temperature. It was observed that the GTA procedure affects only the biological component of the SC/PVA and gelatin/PVA blends, whilst the thermal treatment influences mainly the synthetic polymer. In the case of HA/PVA hydrogels, a modulus variation was found with the HA content related to the organization degree and perfection of the PVA network structure. It seems evident that, in the experimental conditions used, dextran/PAA mixtures behave as miscible blends showing a glass transition intermediate between those of the pure components. With both untreated and GTA-treated gelatin/PMAA blends, it was not possible to evaluate the miscibility of the systems; it could only be affirmed that these materials show good mechanical properties over a wide range of temperature. © 1997 SCI.     

Study of the behavior of blends of a poly(hydroxybutyrate‐valerate) copolymer,polypropylene, and SEBS

Polyhydroxyalkanoates are a type of polymers with a clear renewable origin, as different types of microorganisms can produce them. Unfortunately, their mechanical properties are not usually as good as those of conventional polymers and for a moment their price is relatively higher; these are two of the reasons why it is suggested in the bibliography that they can be employed forming part of blends with conventional polymers. In the present work, blends of a poly(hydroxybutyrate‐valerate) (PHBV) copolymer and a polypropylene resin have been successfully processed using PHBV concentrations up to 20 phr with internal mixer and a hot plate press. Processability and applicability of such blends logically depend on their properties, and for this reason morphology, rheological, thermal properties, and tensile strength for all samples have been evaluated. Ternary blends, incorporating a poly(styrene‐ethylene‐butylene) copolymer have also been obtained and the influence of the blends properties has been analyzed. Results have shown that the rheological behavior and crystallization process of the system is markedly dependent on the blend composition. Although tensile strength significantly decreases with PHBV concentration, the use of low concentrations of the styrene‐ethylene‐butylene‐styrene copolymer could improve the elongation at break to a certain extent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical Properties and Morphology of Recycled. Plastic Wastes by Solution Blending

In this study, bottles of mineral water and yogurt as well as Styrofoam bowls were recycled and identified by infrared spectroscopy as poly(vinyl chloride) (PVC), high-impact polystyrene (HIPS), and polystyrene (PS). Solution blending was employed to make polymer blends from these recycled plastics, including PVC/PS, PVC/HIPS/PS blends, and PVC/HIPS blends with or without a com-patibilizer, styrenelp-chlorostyrene (ST-CMS). Thermal behavior from differential scanning calorimetry was used to examine the compatibility of the blends. For the PVC/PS and PVC/HIPS/PS systems, it is found that although the third component (HIPS) may not be good enough as a compatibilizer, the addition of HIPS to the two-component blend (PVC/PS) may enhance the mechanical properties at the specific composition, especially for the blends at the intermediate concentrations. For PVC/HIPS blends with the ST-CMS copolymer as a compatibilizer, all the mechanical properties of the blends except the elongation at break, in general, increased with increasing the concentration of compatibilizer due to the increase of compatibility. The abnormal fracture strain was attributed to the differences in adhesion when various amounts of ST-CMS was added. The results of mechanical properties of the blends were consistent with the morphology from scanning electron microscopy.     

Study of the Role of Silane-treated Filler on the Compatibility of Polypropylene/Polystyrene Blends at Different Ratios

A systematic study of the effect of the filler on the immiscible blend properties is presented as a function of the blend composition. As a representative of semicrystalline polymer/amorphous polymer blends, a polypropylene/polystyrene system was chosen. The presence of filler in the blends has induced significant changes in the rheological properties. This behavior is a function not only of filler surface treatment but also of blend composition. Solid state dynamic mechanical analysis is performed and the relaxation behavior is correlated with the morphology of the blends. The increase in tensile strength of the blends filled with surface-treated glass beads is related to the enhancement of the adhesion and polymer/polymer interactions.     

Melt rheology of poly(lactic acid): Consequences of blending chain architectures

The rheology of blends of linear and branched poly(lactic acid) (PLA) architectures is comprehensively investigated. Measurement of the melt rheological properties of PLA is complicated by degradation effects but the addition of 0.35 wt% tris(nonylphenyl) phosphite (TNPP) provides excellent stabilization over a range of temperatures. Master curves of dynamic viscosity constructed using time‐temperature superposition show significant dispersion for unstabilized samples; this behavior is accompanied by a loss of molecular weight. TNPP stabilized samples show excellent superposition throughout the entire frequency range and minimal loss in molecular weight. For the linear architecture, the Cox‐Merz rule is valid for a large range of shear rates and frequencies. The branched architecture deviates from the Cox‐Merz equality and blends show intermediate behavior. Both the zero shear viscosity and the elasticity (as measured by the recoverable shear compliance) Increase with increasing branched content. The viscosities of both the unstabilized samples and the TNPP stabilized samples roughly obey a log additivity mixing rule. The recoverable shear compliance is monotonic in blend composition and a mixing rule for this property is also presented. For the linear chain, the compliance is independent of temperature but this behavior is apparently lost for the branched and blended materials. Tensile and thermal properties of the blends are also measured and found to be roughly equal within the statistical error of the experiments. The results suggest that excellent control over rheological behavior of PLA is possible through blending chain architectures without compromising mechanical properties.     

Morphology and micromechanical deformation behavior of styrene–butadiene block copolymers. IV. Structure–property correlation in binary block copolymer blends

The structure–property correlation in blends consisting of styrene/butadiene block copolymers forming alternating polystyrene (PS) and polybutadiene (PB) lamellae, and PS domains in rubbery matrix was investigated by different microscopic techniques (transmission electron microscopy, scanning force microscopy, and scanning electron microscopy), uniaxial tensile testing, and dynamic mechanical analysis. Unlike the pure lamellar block copolymer, the blends showed predominantly disordered wormlike morphology formed by the intermolecular mixing. These structures allowed a precise control of stiffness/toughness ratio of the blends over a wide range. The blends showed a gradual transition from predominantly viscoplastic to elastomeric behavior with increasing triblock copolymer content. The results demonstrated that the binary block copolymer blends provide the unique possibility of tailoring mechanical properties on the basis of nanostructured polymeric materials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1219–1230, 2004     

Properties of a thermotropic liquid crystalline polymer blended with different thermoplastics

Thermal, rheological, morphological, and mechanical properties of a thermotropic liquid crystalline polymer, TLCP (copolyester Vectra A-950 from Hoechst), blended with a polycarbonate (PC), a polyethylene glycol terephthalate (PETG), and a blend of PC and PETG (20/80) are presented and discussed. Important supercooling effects are observed for the TLCP. For the blends the glass transition temperature of the matrix is shown to decrease slightly, suggesting partial miscibility of the components. A finer dispersion is observed for the TLCP/PC blends, at least for TLCP concentrations lower than 20%, for which the mechanical properties are quite good. For higher TLCP concentrations, as well as for the other two matrices, the mechanical properties follow more or less the mixing rule, and the morphology of the blends suggests poor adhesion. We were unable to obtain fibrillar structures by extruding the blends through a capillary rheometer; in the TLCP/PC blends, the TLCP domains were too small, and for the other blends the extrudates had not enough melt strength.     

Morphology and properties of isotactic polypropylene modified with hydrocarbon resin MBG273. I. Binary blends

We investigated a system formed of isotactic polypropylene (iPP) and hydrogenated hydrocarbon resin MBG273 (up to 30 wt % resin) to study the influence of the composition on the morphology, structure, and properties of its blends and derived films. All the blends, after the mixing of the components in the melt and cooling at room temperature, were formed by a crystalline phase of iPP and by one homogeneous phase formed by amorphous iPP and the MBG273 resin. The presence of MBG273 did not influence the crystalline structure of iPP, which remained, for every blend, α‐monoclinic, but it reduced the crystallization temperature and nucleation density of iPP. Differential scanning calorimetry and dynamic mechanical thermal analysis showed an increase in the glass‐transition temperature with the resin content, confirming the formation of one amorphous phase. Tensile property analysis indicated an increase in Young's modulus and a decrease in the elongation at break of films as a function of the resin content in the blends. The water vapor permeability and tensile mechanical properties were related to an increase in the glass transition with the addition of MBG273. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3454–3465, 2004     

Rheological properties of linear low density polyethylene/polypropylene blends. Part 2: Solid state behavior

This second paper of a series continues the examination of the tensile properties of two series of linear low density polyethylene/polypropylene, (LLDPE/PP) blends. The blends were prepared using a twin-screw extruder and cover the whole concentration range, An Instron Universal Tensile Tester was used to measure the tensile properties of the blends between 10 and 70°C, and the temperature and composition dependences of the modulus were examined. A comparison is established between the solid state and melt properties to underline the behavior in the PP rich region. Results of dynamic mechanical experiments and differential scanning calorimetry on the same materials are also given, and the mechanical behavior is discussed in terms of the variation of the system's crystallinity.     

A morphological study on the migration and selective localization of graphene in the PLA/PMMA blends

Nano‐filled polymer blends offer the opportunity to obtain materials with fine‐tuned properties. In this work, the dispersion and localization behavior of graphene nanoplate (GNP) and graphene oxide (GO) in solution mixed blends of polylactic acid (PLA) and polymethyl methacrylate (PMMA) were investigated. The blends were prepared by using different mixing sequences to investigate the effect of kinetics parameters and surface chemistry of filler as well as thermodynamics affinity on the localization of fillers. Field Emission Scanning Electron Microscopy (FESEM) and Rheometric Mechanical Spectroscopy (RMS) were employed. In addition, graphene materials were compared by Fourier transform infrared and Raman spectroscopy as well as elemental analysis characterization. Results showed that depending on the mixing sequence, the GNPs were localized in the both phases and interface through migration to reach thermodynamics equilibrium. However, GO localization was significantly affected by the mixing sequence due to better interaction with the polymer phases. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43799.