Effect of Blend Preparation on Electrical,Dielectric, and Dynamical‐Mechanical Properties of Conducting Polymer Blend: SBS Triblock Copolymer/Polyaniline

Conducting polymer blends based on styrene–butadiene–styrene (SBS) triblock copolymer and polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) were prepared by different procedures: mechanical mixing (MM) and ‘in situ’ polymerization (ISP) methods. The ISP blends exhibited higher levels of electrical conductivity, as compared to MM blends. The scanning electron micrographs of the ISP blend were characterized by the presence of microtubules, which favored the formation of the conducting pathways inside the SBS matrix. From dynamic mechanical and dielectric analysis, it was possible to suggest a higher interaction degree of the polyaniline with the polystyrene phase of the block copolymer. Blends prepared by ISP method displayed also higher dielectric constant and higher dielectric loss factor than blends prepared by MM method.

     

Conducting SBS block copolymer–polyaniline blends prepared by mechanical mixing

Polyaniline was doped with dodecylbenzenesulfonic acid (Pani · DBSA) in an agate mortar and used as a conductive additive in melt blends with styrene–butadiene–styrene (SBS) block copolymer. These blends exhibit relatively high levels of electrical conductivity at low‐weight fractions of the polyaniline complex. The melt blending process, performed in a two‐roll mill or in a Haake internal mixer, increased the protonation degree of the Pani · DBSA, as indicated by X‐ray photoelectron spectroscopy analysis. This result confirms the occurrence of a second doping process at high temperature. The mechanical performance decreases as the amount of Pani · DBSA in the blend increases, indicating a plasticizing effect of the DBSA. The higher temperature used in blending imparts better conductivity value but gives rise to a strong crosslinked material because of the presence of the sulfonic acid and the high extent of double bonds in the SBS compound. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 626–633, 2001     

SBS/Polyaniline or Carbon Black System: Finding the Optimal Process and Molding Temperatures Through Experimental Design

Summary: The optimum mixing and molding conditions for processing of styrene‐butadiene‐styrene (SBS) triblock copolymer filled with carbon black (CB) or polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) were determined. The mechanical performance of SBS/CB and SBS/Pani.DBSA composites were characterized in terms of strain and stress responses at break condition. In order to reach this goal, two mixed two‐ and three‐level factorial designs were employed. The obtained data show that the molding temperature is the most important parameter to affect the mechanical behavior of the systems. Among the systems analyzed, the SBS/Pani.DBSA blends presented the highest sensitivity to the process and molding conditions.

Elongation of composites as a function of molding temperature.     

Influence of Graphite Filler on Physicochemical Characteristics of Polymer/Graphite Composites: A Review

In this article, carbon nanofiller, in particular graphite, has been reviewed for the preparation of polymer-based composites. The dispersion of graphite relies on fabrication methods employed such as solution mixing, melt blending, and in situ polymerization. The consequences of surface modification on thermal, mechanical, and electrical characteristics were explored. Moreover, the properties and parameters involved in feature enhancement of graphite-based materials have been highlighted. Topical development in field of thermal, mechanical, and other physical properties of polymer/graphite composites was investigated. Furthermore, worth of materials regarding electrodes, resistors, dye-sensitized solar cells, electromagnetic interference shielding, packaging, and flame retardant applications has been discussed.     

X‐ray photoelectron spectroscopy and electrical conductivity of polyaniline doped with dodecylbenzenesulfonic acid as a function of the synthetic method

X‐ray photoelectron spectroscopy (XPS) has been employed to investigate the protonation degree of polyaniline doped with dodecylbenzenesulfonic acid (Pani. DBSA) obtained by different synthetic methods. The protonation degree has been compared to electrical conductivity. Pani.DBSA prepared through the redoping process in an agate mortar displays conductivity values within the range of 1 S/cm. A protonation level of 48% with almost all imine groups being protonated. Pani.DBSA was also synthesized by oxidative polymerization of aniline in the presence of DBSA, which acts simultaneously as a surfactant and as protonating agent. This in situ doping polymerization was carried out in aqueous or toluene media. In both cases, protonation degrees higher than 50% have been achieved, indicating that a substantial portion of amine units have also been protonated. Higher doping degree has been achieved by aqueous dispersion polymerization of aniline. The C/N and S/N molar ratios obtained by XPS analysis indicate that the polyaniline chains obtained by in situ polymerization are protonated by both sulfonate and hydrogen sulfate anions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 556–565, 2001     

Studies on the dynamically vulcanized polypropylene (PP)/butadiene styrene block copolymer (SBS) blends: Mechanical properties

Unvulcanized and dynamically vulcanized blends of isotactic polypropylene (PP) and butadiene styrene block copolymer (SBS) in the composition range of 10–40 wt % SBS were prepared by melt mixing in an internal mixer and evaluated for impact and tensile properties. Dynamic vulcanization of blends gave superior mechanical properties. Systematic changes with varying blend composition were found in stress-strain behavior in both the blend systems. The effect of blend composition on the state of dispersion and morphology of the dispersed phase droplets were studied by scanning electron microscopy. Analysis of the yield stress data in terms of various theoretical models revealed the variation of stress concentration effect with blend composition and higher interphase adhesion in dynamically vulcanized blends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2691–2701, 1997     

Studies on mechanical behavior high impact polystyrene/vinyl clay nanocomposites: Comparison between in situ polymerization and melt mixing

A comparative study on various synthesis methods like melt mixing (MM) and in situ polymerization (ISP) of high impact polystyrene/vinyl clay nanocomposites (HIPS/VNCs) is attempted here. In ISP, nanocomposites were prepared by mixing vinyl clay (VC) and poly butadiene rubber (PBR) in styrene with the initiator, azo bis isobutyronitryle. Melt compounding was conducted in two ways–commercial melt mixed blend where Commercial HIPS was mixed with VC and in situ melt mixed blend, where, nanocomposites were prepared by mixing polystyrene, PBR, and VC. The effect of dispersion of the nanoclay on the morphology and material properties of HIPS/VNCs was compared for all the methods, and it is found that the product obtained by ISP gives better properties when compared with MM. Moreover, the dispersion of the clay in the matrix is greater by in situ method, which is evident from X‐ray diffraction pattern and scanning electron microscopic analysis. Statistical analysis of ISP was carried out by design expert software version 8.0.7.1. Modeling and Optimization of the mechanical properties were done by using central composite design of response surface methodology. POLYM. COMPOS., 38:68–76, 2017. © 2015 Society of Plastics Engineers     

Effect of styrene–isoprene–styrene,styrene–butadiene–styrene,and styrene–butadiene–rubber on the mechanical,thermal, rheological,and morphological properties of polypropylene/polystyrene blends

The mechanical, thermal, rheological, and morphological properties of polypropylene (PP)/polystyrene (PS) blends compatibilized with styrene–isoprene–styrene (SIS), styrene–butadiene–styrene (SBS), and styrene–butadiene–rubber (SBR) were studied. The incompatible PP and PS phases were effectively dispersed by the addition of SIS, SBS, and SBR as compatibilizers. The PP/PS blends were mechanically evaluated in terms of the impact strength, ductility, and tensile yield stress to determine the influence of the compatibilizers on the performance properties of these materials. SIS‐ and SBS‐compatibilized blends showed significantly improved impact strength and ductility in comparison with SBR‐compatibilized blends over the entire range of compatibilizer concentrations. Differential scanning calorimetry indicated compatibility between the components upon the addition of SIS, SBS, and SBR by the appearance of shifts in the melt peak of PP toward the melting range of PS. The melt viscosity and storage modulus of the blends depended on the composition, type, and amount of compatibilizer. Scanning electron microscopy images confirmed the compatibility between the PP and PS components in the presence of SIS, SBS, and SBR by showing finer phase domains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 266–277, 2003     

SBS／ESBS共混体系力学性能及熔体流动速率的研究

研究了苯乙烯-丁二烯-苯乙烯（SBS）和环氧化苯乙烯-丁二烯-苯乙烯（ESBS）质量配比及ESBS环氧基质量分数对SBS／ESBS共混物的力学性能以及熔体流动速率的影响。结果表明,随着SBS与ESBS质量配比的减小,共混物的绍尔A硬度逐渐增大,拉伸强度和断裂伸长率先增大后减小,熔体流动速率先减小后增大。当SBS和ESBS质量配比为60：40时,共混物的邵尔A硬度为85,拉伸强度和断裂伸长率分别为26．86MPa和795．5％,综合性能最佳。随着ESBS环氧基质量分数的增大,SBS／ESBS共混物的硬度逐渐增大,拉伸强度和断裂伸长率降低,熔体流动速率变小。     

Compatibilizing Effects of In Situ Formed Block Copolymers in Binary Blends

Four types of binary blends—Type A, Type B, Type C, and Type D—were prepared by melt mixing them in a single screw extruder, with an emphasis on the compatibilizing effect of in situ formed block copolymers between MAH-g-PP and nylon 6. The effects were examined in terms of morphological, rheological, thermal, dynamic mechanical, and mechanical properties for four types of binary blends using various methods.     

Effects of reactive melt mixing on the morphology and thermal behavior of linear low-density polyethylene/rubber blends

Linear low-density polyethylene (LLDPE)/polybutadiene (PB) and LLDPE/poly(styrene-b-butadiene-b-styrene) (SBS) binary blends were prepared by simple melt mixing or by reactive blending in the presence of a free-radical initiator, and for comparison, pure LLDPE was treated under the same conditions with a comparable free-radical initiator concentration. The effect of the reactive melt mixing on the morphology of the blends was studied with transmission electron microscopy, and the corresponding particle size distributions were analyzed and compared to highlight the effects of the crosslinking and grafting phenomena. Thermal properties of the obtained materials were investigated with differential scanning calorimetry and dynamic mechanical thermal analysis (DMTA). In particular, the effect of the reactive mixing parameters on the amorphous phase mobility was investigated. The influence of the chemical modification on the crystallization behavior of LLDPE, neat and blended with PB and SBS, was also studied with dynamic and isothermal differential scanning calorimetry tests, and the isothermal thermograms were analyzed in light of the Avrami equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Compatibilization of polystyrene and low density polyethylene blends by a two-step crosslinking process

A new method has been developed to compatibilize the blends of polystyrene (PS) and polyethylene (PE). Polyethylene is first crosslinked partially by using a small amount of dicumyl peroxide (DCP) in a mixer at 165°C. Then the crosslinked PE is melt-blended with PS for another 5 min. Finally, a styrene–butadiene–styrene block copolymer (SBS) is added to the melt and mixed for another 5 min. We refer to this special procedure as the two-step crosslinking process. During the final mixing step of this process, the residual free radicals in the PE react with SBS. The crosslinking that occurs between PE and SBS has a significant impact on the mechanical properties of the blends including the impact strength, the tensile modulus, and the elongation-at-break. Scanning electron microscopy (SEM) results indicate that the interfacial adhesion is increased significantly, even though the domain sizes have not changed significantly in comparison with the non-crosslinked system. Transmission electron microscopy (TEM) results indicate that a thin SBS interfacial layer fully encapsulates the PE particles. This method could also be applied to other blend systems containing at least one component and a compatibilizer that are crosslinkable.     

Morphology and mechanical properties of thermoplastic elastomers from nylon-nitrile rubber blends

Nylon-nitrile rubber blends having different plastic-rubber component ratios (100/0, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 0/100) were prepared by melt mixing technique in a Rheocord-90 at a temperature set at 180°C. The mixing characteristics of the blends have been analyzed from the rheographs. The morphology of the blend was studied using optical and electron microscopies, with special reference to the effect of blend ratio. The micrographs indicate a two-phase system where the component having lower proportions was found to disperse in the major continuous phase. A cocontinuous morphology was observed for 50/50 composition. Mechanical properties of the blends have been measured according to standard test methods. The effect of blend ratio on the mechanical properties like tensile strength, tear strength, elongation at break, stress-strain behavior, and hardness has been analyzed. The influence of the strain rate on the mechanical properties has also been analyzed. The mechanical properties were found to have a strong dependence on the amount of nylon in the blend. It is found that the blends with higher proportions of nylon have superior mechanical properties. The observed changes in mechanical properties are explained on the basis of the morphology of the blend. Various theoretical models such as Series, Parallel, Halpin-Tsai, and Coran's equations have been used to fit the experimental mechanical data. © 1996 John Wiley & Sons, Inc.     

Blends of styrene–butadiene–styrene triblock copolymer and isotactic polypropylene: morphology and thermomechanical properties

A set of blends of styrene–butadiene–styrene triblock copolymer (SBS) and isotactic polypropylene (i‐PP) in a composition range 0–100 % polypropylene by weight was prepared in a twin screw extruder. The morphology of the blends has been studied by transmission electron microscopy. The blends present phase separation. Dynamic mechanical measurements show an improvement of the mechanical properties of SBS when i‐PP is the dispersed phase. This reinforcing effect can be observed even at high temperatures when i‐PP is in the rubbery state. The mechanical properties of the blends have been interpreted using Takayanagi's block model. The melting and crystallization behaviour of the i‐PP in the blends has been studied by differential scanning calorimetry. The fractionated crystallization phenomenon has been observed in the blends where i‐PP forms the dispersed phase. The results are consistent with the morphology shown by the blends, in particular, with its phase inversion, which occurs at a composition near to 50% i‐PP. © 2000 Society of Chemical Industry     

碳纳米管/橡胶复合材料的制备与性能研究进展

介绍了碳纳米管/橡胶复合材料的直接共混、溶液共混、乳液共混、熔融共混、原位聚合制备工艺,综述了碳纳米管/橡胶复合材料的加工性能、力学性能和电性能,指出今后的发展方向是开发新的碳纳米管制备技术、探索碳纳米管的纯化和改性方法、研究碳纳米管/橡胶复合材料的制备技术及其结构与性能的关系.     

Advances in Epoxy/Graphene Nanoplatelet Composite with Enhanced Physical Properties: A Review

In this review, development from graphene nanoplatelet, that is, comprised of short bulk of single layer graphene, into modified-polymer/graphene nanoplatelet composite is presented. Preparation methods of graphite, graphene, and graphene nanoplatelets have also been discussed. Graphene nanoplatelet and modified graphene nanoplatelet commend unique properties to composites such as excellent thermal and electrical conductivity as well as mechanical and barrier properties. Graphene nanoplatelet fabrication techniques by solution mixing, melt blending, and in situ polymerization are also discussed. Excellent dispersion of nanoplatelets in polymer/graphene nanoplatelet depends upon the selection of suitable fabrication technique. Moreover, the corresponding significance, exploitation, challenges, and future aspect of polymer/graphene nanoplatelet-based material is overviewed.     

Study on properties and stress relaxation behavior of oil-extended SBS/LLDPE/EVA blends

In order to explore and develop a new sealing material, the oil-extended styrene-butadiene-styrene (SBS)/Linear low density polyethylene (LLDPE)/ethylene-vinyl acetate (EVA) blends were prepared by melt mixing method and the effects of components on mechanical, rheological properties, and microstructure of the blends were investigated. The results showed that the resilience of the blends was barely changed during three-time cyclic compression. The increase of oil-extended SBS content would reduce the hardness of the blends as well as its compatibility and increase the melt flow rate. An increase in the LLDPE content, however, has the opposite effect on the blends. In contrast, EVA has little effect on the mechanical and rheological properties of the blends, but its addition could improve the transparency of samples effectively while promote the phase separation of the sample and complicate its microstructure. The master curve of stress relaxation modulus obtained by time–temperature superposition principle could be used to predict the long-term (1.5 × 10⁸ s, about 4.7 years) stress relaxation behavior of the blends at room temperature while the correlation coefficient of the shift factor fitting is 0.987. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48930.     

A new method of preparation of a rubber-modified polyamide directly during caprolactam polymerization

A new method to obtain a rubber-modified polyamide 6 (PA6) directly during the polymerization of the caprolactam (CL) is described. Binary and ternary blends containing ethylene-propylene random copolymers (EPM) and/or a fictionalized EPM rubber (EPM-g-SA) were prepared and their morphology as well as their mechanical properties were investigated as function of composition and reaction conditions. It was found that the morphology of the blends is strongly dependent on the method of preparation. More complex structures are observed in blends obtained with the “Solution” preparation. For a better resolution of the morphology, the smooth ultramicrotomed surfaces were exposed to boiling xylene before SEM (scanning electron microscopy) examination. The rubbery phases are selectively dissolved whereas the PA6 matrix is left. The tensile mechanical properties and the Izod impact behavior are related to the mode and state of dispersion of the rubbery components. The impact properties of ternary PA6/EPM/EPMg-SA (80/18/2) and (80/15/5) blends, prepared during the CL polymerization are comparable to those of similar blends obtained by usual melt mixing procedures.     

PP／PS合金技术进展

PP和PS是不相容的聚合物 ,直接机械共混的产物性能较差 ,通过添加相容剂 ,如嵌段共聚物或接枝共聚物能提高共混物性能。在线增容技术已用于PP、PS反应性增容 ,生产高性能的合金。     

PP／SBS／纳米CaCO3复合材料结构与性能研究

研究了PP/SBS/纳米CaCO3复合材料的力学性能以及SBS分散相颗粒和纳米CaCO3粒子在PP基体中的分散状况。结果表明,纳米CaCO3粒子的加入使复合材料的缺口冲击强度、弯曲弹性模量、拉伸强度均得到提高。透射电镜观察发现,纳米CaCO3粒子的加入使复合体系的熔体黏度增大,对弹性体SBS的分散起到剪切细化、均化的作用,从而起到协同增韧效应。