聚合物共混相容性研究进展

介绍了聚合物共混相容性的热力学理论，讨论了相容性的实验表征方法，包括共混物形态和物性表征等，提出了改善聚合物相容性的重要途径及其进展。     

Criteria for rheological compatibility of polymer blends

Criteria for rheological compatibility of polymer blends are suggested. The criteria suggested make use of plots of first normal stress difference (N₁) against shear stress (σ₁₂), and of storage modulus (G′) against loss modulus (G″). Compatible blend systems considered are (1) blends of two different grades of low-density polyethylene, (2) blends of poly(vinylidene fluoride) and poly(methyl methacrylate), (3) blends of poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene, and (4) blends of poly(styrene-co-acrylonitrile) and poly(styrene-co-maleic anhyride). And incompatible blend systems considered are (1) blends of nylon 6 and poly(ethylene-co-vinyl acetate) and (2) blends of nylon 6 and an ethylene-based multifunctional polymer. It has been found that plots of N₁ vs. σ₁₂ and G′ vs. G″ give (a) temperature-independent correlations for both compatible and incompatible blend systems; (b) composition-independent correlations for compatible blends; (c) composition-dependent correlations for incompatible blends.     

聚合物共混相容性分子模拟进展

从分子模拟角度介绍如何模拟聚合物共混物相容性的方法,引入了溶解度参数和玻璃化温度。概括叙述了用分子模拟方法研究聚合物共混相容性的现状及应用,对分子模拟发展趋势作了展望。     

Modeling the electrical percolation of mixed carbon fillers in polymer blends

A model based on excluded volume theory is proposed for describing the electrical percolation of mixed carbon fillers in polymer blends by adjusting the unit volume of the previous model concerning mixed carbon-filler-filled single polymer systems. An equation capable of predicting the percolation threshold from those of individual carbon fillers in the single matrix polymer is developed from the model and further corrected to suit the actual situation. The corrected equation fits the experimental results obtained from multi-walled carbon nanotubes/carbon black-filled polybutylene terephthalate/styrene–acrylonitrile (SAN), polycarbonate (PC)/SAN and PC/acrylonitrile–butadiene–styrene blends well. The model and equation show clearly the advantages of using both mixed fillers and polymer blends, and can provide an important theoretical basis for designing the structures and predicting the electrical properties of conductive polymer composites.     

用浓乳液法制备PS/PBMA/PEGD自相容高分子合金

用浓乳液聚合方法，将可聚合大分子单体与其他单体通过原位共聚合生成增容剂，制备了PS/PBMA/PEGO自相容高分子合金。结果表明，凝胶质量分数低于43.4%的高分子合金具有较好的加工性能。     

Dispersion of fillers and the electrical conductivity of polymer blends filled with carbon black

Dispersion state of carbon black(CB) was studied in polymer blends which are incompatible with each other. It was found that CB distributes unevenly in each component of the polymer blend. There are two types of distribution. (1) One is almost predominantly distributed in one phase of the blend matrix, and in this phase fillers are relatively homogeneously distributed in the same manner as a single polymer composite. (2) In the second, the filler distribution concentrates at interface of two polymers. As long as the viscosities of two polymers are comparable, interfacial energy is the main factor determining uneven distribution of fillers in polymer blend matrices. This heterogeneous dispersion of conductive fillers has much effect on the electrical conductivity of CB filled polymer blends. The electrical conductivity of CB filled polymer blends is determined by two factors. One is concentration of CB in the filler rich phase and the other is phase continuity of this phase. These double percolations affect conductivity of conductive particle filled polymer blends.     

Stability and compatibility in blends of silicone and vinylacrylic polymer emulsions

Special, unexpected properties may arise from blending of polymer emulsions, depending on the miscibility and stability of the resulting dispersions on the one hand, and the morphology of the films obtained upon drying on the other hand. In the field of water-repellent paints, blends of silicone and vinylacrylic copolymer emulsions have been previously shown to be a tricky means to associate binding ability and water permeability properties in the same material. It is currently assumed that the resulting morphology and physical properties of films obtained from these blends upon drying is partially controlled by the compatibility of the two kinds of polymers. In the present paper, the crucial problem of stability and compatibility in blends of silicone and vinylacrylic copolymer emulsions is investigated; more particularly, the effect of pH of the vinylacrylic copolymer latex, as well as the influence of the stabilizing system of both emulsions, on the stability of emulsion blends is qualitatively described. As regards the morphology of the films, the strong incompatibility of the two polymers is shown, which results in large macroscopic heterogeneities in the dried composite films. Furthermore, semi-quantitative angle-resolved ESCA measurements have evidenced a pronounced diffusion of the silicone species towards the surface of the samples. Investigations into different ways to increase compatibility of the two phases is presented. It is shown that phase separation at the macroscopic scale can be controlled either by lowering the interfacial tension between the two phases by grafting silane compatibilizers on to the latex particles, or by decreasing the molecular mobility of the silicone phase by cross-linking. Diffusion of the silicone chains towards the surface of the composite films can only be significantly restricted by cross-linking of this species.     

AN含量对PVC/SAN共混物相容性的影响

采用乳液聚合技术合成了一系列不同丙烯腈（AN）含量的苯乙烯-丙烯腈（SAN）共聚物,将其与聚氯乙烯（PVC）熔融共混,形成PVC/SAN共混物,并引入增塑剂邻苯二甲酸二辛酯（DOP）。通过动态力学分析仪（DMA）和扫描电子显微镜（SEM）对共混物的玻璃化转变温度和相结构进行表征,考察不同AN含量对PVC/SAN共混物相容性的影响。     

Structuration,selective dispersion and compatibilizing effect of (nano)fillers in polymer blends

Hybrid ternary blends comprising two polymers and one mineral (nano)filler are increasingly studied because they are starting to be widely used to respond to industrial issues. The objective of this review is to gather information on these particular systems. Concerning first thermodynamic effects of fillers on the phase separation of an immiscible polymer blend, Flory–Huggins theory demonstrate stabilization. This theory was particularly taken up and developed for the case of two polymers and one filler by Lipatov and Nesterov in the 90s. More recently, Ginzburg generalized this theory to the case of unfavorable enthalpic interactions between a particle and the two polymers. They showed that the amount of particles had to attain a certain threshold to stabilize the system and the lower the particle radius, the higher the stable zone area. Generally speaking, all the phenomena regarding the morphology of polymer blends are governed by thermodynamics and/or kinetic effects, as well as the localization of nanoparticles. The main discussed thermodynamically controlling parameter of the localization is the wetting parameter ω_AB. However, because of the viscosity of the system, the equilibrium dictated by ω_AB may never be reached. Hence, concerning the kinetic effects, the final localization of fillers in a polymer pair is guided by the sequence of mixing of the components, the viscosity ratio, the composition, the temperature, the shear rate and the time of mixing. When the particles are placed at the interface between two polymers, coalescence can be suppressed or/and interfacial tension can be reduced. In that case, particles are known to play the role of a compatibilizer. In a ternary system, (i) the shape of the particle (spheres, rods or “onions-shape”), (ii) the particle radius (R_p) versus the radius of gyration of the polymers (R_g) and (iii) the surface chemistry of the particles affect the final localization of the particles (thus, the compatibilizing effect) and the final properties of the material, such as mechanical, conductive, magnetic and thermal properties. This review details recent works for which those four above mentioned properties are improved by incorporating different kind of fillers in polymer blends.     

Effect of multiblock copolymers in polymer blends

The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2293–2309, 1997     

Chitosan blends as fillers for paper

The presented studies are focused on the dependence of paper sheet strength properties such as tear resistance, burst, and extensibility on the composition of additive [chitosan blends with poly(vinyl alcohol) and gelated starch]. Chitosan acetate (cationic) and its blends caused an improvement of the strength properties of paper sheets by the substantial modification of cellulose (anionic) fibers, probably through the presence of strong ionic interactions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3210–3215, 2000     

Effect of fillers on morphological properties and wear characteristics of XNBR/NR blends

The blends of carboxylated acrylonitrile butadiene rubber (XNBR) and natural rubber (NR) were prepared using a blending technique in the presence of different types of carbon black. The effect of filler on morphological and wear characteristics was studied. ISAF N234 carbon black showed a significant effect on curing, mechanical, and thermal studies. The DIN abrader results showed high abrasion resistant properties of 80 wt % NR and 20 wt % XNBR with ISAF N234. The rubber compound containing 40 wt % of NR and 60 wt % of XNBR with ISAF N234 is found to be the toughest rubber against all types of rock. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:710–718, 2011     

Effect of conducting fillers on the microstructure and electrical conductivity of thermoplastic polymer composites

Summary This paper reports on the synthesis and characterization (electrical, mechanical, thermal and dynamic mechanical) of electrically conducting polymer composites based on thermoplastic matrices (low density polyethylene (LDPE) and polypropylene (PP)) and two conducting fillers: iron particles (Fe) and carbon black (CB). The addition of Fe allows the easy incorporation of higher amounts of CB. Results suggest that the electrical and mechanical properties of these materials are improved by the presence of both fillers being necessary the addition of CB to achieve interesting values of conductivity. On the other hand, the crystalline structure of the polymer matrix is gradually reduced with the incorporation of both fillers but Fe by itself does not affect the geometry of growing crystals.     

Effect of fillers on morphological properties in NR/SBR blends for OTR tyres

Abstract

The blends of styrene butadiene rubber (SBR) and natural rubber (NR) are prepared using a two-roll mixing mill in the presence of different types of carbon blacks as reinforcing filler. The effects of fillers on cure characteristics and thermal, dynamic–mechanical, morphological properties of the blends are studied. The ISAF N231 type of carbon black shows a significant effect on tensile, tear and modulus properties by reacting at the interface between SBR/NR matrixes. The dynamic characteristics and storage modulus of SBR/NR with SAF N110 and SRF N774 types of carbon black show distinct characteristics in respect to all other blends in this system. The thermal stability of the rubber vulcanizates containing SAF N110 and SRF N774 types of carbon blacks is higher than other blend types. With the increasing percentage of SBR to NR, the thermal stability of the blend is increased. However, the heat buildup of the blends increases with the increase in SBR percentage.     

挤出共混中的高剪切应力对PP-HDPE-滑石粉共混材料力学性能的影响

采用提高双螺杆挤出机螺杆转速的方法,研究了双螺杆挤出机的高剪切应力作用对聚丙烯(PP)、PP-滑石粉和PP-高密度聚乙烯(HDPE)-滑石粉共混材料力学性能的影响.结果表明:双螺杆挤出机的高螺杆转速、高剪切应力作用,可促进材料中滑石粉颗粒的均匀分散、促进HDPE均匀分散于PP基体的乙丙共聚物的相态之中,可引起PP或HDPE的断链反应、引起HDPE大分子自由基与PP基体中的EPR相以及与滑石粉表面偶联助剂之间的结合反应,引起共混材料缺口冲击强度的显著增大;少量极性烯类单体的加入和较低的挤出反应温度条件(180℃)有利于形成的大分子自由基与极性烯类单体的接枝、嵌段反应、界面间的偶联结合反应及其原位增粘作用,并引起PP-HDPE-滑石粉共混材料缺口冲击强度的进一步增大.     

Effect of casting solvent on the heterogeneity of films of polymer blends

The miscibility window of the 50/50 w/w poly(styrene-co-4-vinylphenyl)-dimethylsilanol/poly(n-butyl methacrylate) (ST-VPDMS/PBMA) blends prepared from toluene was studied and determined to be in the VPDMS composition range of 4 to 18 mole% in the copolymers. The observed miscibility window was to be compared to the range of 9 to 34 mole% found for the blends prepared from methyl ethyl ketone which was capable of competing for hydrogen bonding. The fact that the observed miscibility windows are influenced by the choice of solvents illustrates that an equilibrium state of polymer mixing is not always attained in solvent casting films and that caution needs to be exercised in studying polymer miscibility when solvent cast films are used.     

Effect of mixer resident time on the overall moduli of polymer blends

The overall moduli tensor of polymer blends is one of the most important characteristics of microscopic morphology development. This article focused on the analysis of dependence of the moduli on mixer resident time in terms of polypropylene–polystyrene (PP/PS) and polypropylene– polyamide1010 (PP/PA1010) blends. Tensile tests on the PP/PS and PP/PA1010 blends with a series of mixer resident times showed a marked change during the initial mixing stage, which may be due to the evolution of particle size and distribution from inhomogeneous to homogeneous. The two cases of periodic spatial distribution of the identical spherical particles were proposed to model the well‐ dispersed and slightly aggregating morphologies in the steady state. Based on the micromechanical model, the moduli of polymer blends were calculated by incorporating the influences of spatial distribution and Poisson's ratio of dispersed particles. Theoretical results indicated that spatial distribution should have little effect on the overall moduli in the steady state. Analysis of the blend system PP/PA1010 with and without compatibilizing agent showed good agreement between the calculations and experiments. Because the interfacial properties were not taken into account, the model gave an overestimate prediction for immiscible blends, like PP/PS for example. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 307–314, 2002     

Effect of polymer-filler surface interactions on the phase separation in polymer blends

For the blends of chlorinated polyethylene and copolymer of ethylene with vinyl acetate, the effect of the introducing filler (fumed silica) on the phase behavior of the blends was investigated. It was found that introducing filler in polymer blends depending on its amount lead either to the increase or to the decrease in the temperature of phase separation. At the filler concentration where both components transit into the state of a border layers, the phase separation temperature increases. This effect was explained by the change of the total thermodynamic interaction parameter in the ternary system polymer-polymer-filler. At lower concentration of a filler, the possible effect is the redistribution of the blend components according to their molecular masses between filler surface (in the border layer) and in the bulk that may diminish the phase separation temperature.Effect of the filler on the phase behavior was explained by the simultaneous action of two mechanisms: by changing the thermodynamics of interaction near the surface due to selective adsorption of one of the components and by the redistribution of components according to their molecular masses between the boundary region (near the surface) and in the matrix.The measurements of the kinetics of phase separation and calculation of the parameters of the activation energy are in agreement with proposed mechanisms.     

Preparation of well‐controlled porous carbon nanofiber materials by varying the compatibility of polymer blends

The relationships between the compatibility in binary polymer blends and the pore sizes of carbon nanofibers (CNFs) prepared from the blends were investigated. Compatibility was determined by the difference between the solubility parameters of each polymer in the polymer blends. Porous CNFs were prepared by an electrospinning and carbonization process using binary polymer blends, consisting of polyacrylonitrile (PAN) as the carbonizing polymer and poly(acrylic acid) (PAA), poly(ethylene glycol), poly(methyl methacrylate) or polystyrene (PS) as the pyrolyzing polymer. The pore size of the CNFs increased with increasing difference in solubility parameter. The CNFs prepared using the PAN/PAA blend, which had the smallest solubility parameter difference, exhibited a pore size of 1.66 nm compared to 18.24 nm for the CNFs prepared using the PAN/PS blend. The prepared CNF webs with controlled meso‐sized pores showed a stable cycle performance in cyclic voltammetry measurements and improved impedance characteristics. This method focusing on the compatibility in polymer blends was simple to apply and effective for controlling the pore sizes and surface area of CNFs for application as electrode materials in energy storage systems. © 2013 Society of Chemical Industry