Effect of morphology on the electric conductivity of binary polymer blends filled with carbon black

Several carbon black (CB)‐filled binary polymer blends were prepared in Haake rheometer. Distribution states of CB and effect of morphology on the electric conductivity of different ternary composites were investigated. Under our experimental condition CB particles located preferentially at the interface between polymethyl methacrylate (PMMA) and polypropylene (PP) in PMMA/PP/CB composites, in high‐density polyethylene (HDPE) phase in PP/HDPE/CB composites, and in Nylon6 (PA6) phase in polystyrene (PS)/PA6/CB, PP/PA6/CB, PMMA/PA6/CB, and polyacrylonitrile (PAN)/PA6/CB composites; the ternary composites in which CB particles locate at the interface of two polymer components have the highest electric conductivity when the mass ratio of the two polymers is near to 1 : 1. The ternary composites in which CB particles located preferentially in one polymer have the highest electric conductivity usually when the amount of the polymer component having CB particles is comparatively less than the amount of the polymer component not having CB particles; if the formulations of PS/PA6/CB, PP/PA6/CB, and PMMA/PA6/CB composites equaled and PA6/CB in them is in dispersed phase, PS/PA6/CB composites have the highest electric conductivity and PP/PA6/CB composites have the lowest electric conductivity; suitable amount of PS or PAN in PA6/CB composites increase the electric conductivity due in the formation of a parallel electrocircuit for electrons to transmit. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and properties of polypropylene‐asphaltene composites

In this study, novel composite materials of polypropylene (PP) with asphaltenes taken from Arab heavy atmospheric residue were prepared and characterized. Composites with various relative amounts of asphaltenes to PP were formed using the melt‐mixing technique. The chemical structure, crystalline form, and morphology of these materials were examined using Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), and scanning electron microscopy (SEM) measurements. Their thermal properties were measured with differential scanning calorimetry (DSC), their thermal degradation characteristics with thermogravimetric analysis (TGA), and the mechanical properties using an Instron dynamometer. It was found that the crystalline and chemical structure of PP is not affected by the presence of asphaltenes, whereas the thermal stability, crystallinity, and tensile mechanical properties are enhanced with the amount of asphaltenes. Particularly, the addition of 5 wt% asphaltenes could improve tensile strength and the Elastic modulus by almost 10%. Better dispersion is achieved at relative low percentages of asphaltenes. It was found that the optimum amount of asphaltenes to result in composites with good dispersion, enhanced thermal stability, tensile strength, and relative crystallinity was 5 wt%. Most of these properties seem to deteriorate when the amount of asphaltenes added is high (i.e., 10%–15%). Therefore, a new use of a by‐product of the petroleum refinery industry is proposed resulting in improved properties of a commodity polymer. POLYM. COMPOS., 38:1957–1963, 2017. © 2015 Society of Plastics Engineers     

Compatibility,rheological, and thermal properties of the melt blends of PEN (HQ/PP) with PEN (HQ/RS)

Two kinds of polyarylene ether nitriles (PEN) copolymers PEN (HQ/PP) and PEN (HQ/RS) were synthesized using 2,6-dicholorobenzonitrile (DCBN) with equal molar of phenolphthalein (PP) and hydroquinone (HQ), DCBN with equal molar of HQ and resorcin (RS), respectively. The melt-mixed blends of two PENs over the complete composition range were characterized by dynamic mechanical analyses (DMA), tensile testing, scanning electronic microscopy (SEM), and capillary rheometer test for their compatibility, thermal, mechanical, and melt flow properties study. DMA show a considerable compatibility between the two PENs. Morphology examinations reveal good component dispersion and strong interface adhesion. The capillary rheometer test found that the blending of PEN (HQ/RS) enhanced the fluidity of the PEN (HQ/PP)/PEN (HQ/RS) blends by reducing its viscosity, which is beneficial to the processability of PEN (HQ/PP). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(methyl methacrylate)‐grafted cellulose nanocrystals: One‐step synthesis,nanocomposite preparation,and characterization

Cellulose nanocrystals (CNCs) are ideal reinforcing agents for polymer nanocomposites because they are lightweight and nano‐sized with a large aspect ratio and high elastic modulus. To overcome the poor compatibility of hydrophilic CNCs in non‐polar composite matrices, we grafted poly(methyl methacrylate) (PMMA) from the surface of CNCs using an aqueous, one‐pot, free radical polymerization method with ceric ammonium nitrate as the initiator. The hybrid nanoparticles were characterized by CP/MAS NMR, X‐ray photoelectron spectroscopy, infrared spectroscopy, contact angle, thermogravimetric analysis, X‐ray diffraction, and atomic force microscopy. Spectroscopy demonstrates that 0.11 g/g (11 wt %) PMMA is grafted from the CNC surface, giving PMMA‐g‐CNCs, which are similar in size and crystallinity to unmodified CNCs but have an onset of thermal degradation 45 °C lower. Nanocomposites were prepared by compounding unmodified CNCs and PMMA‐g‐CNCs (0.0025–0.02 g/g (0.25–2 wt %) loading) with PMMA using melt mixing and wet ball milling. CNCs improved the performance of melt‐mixed nanocomposites at 0.02 g/g (2 wt %) loading compared to the PMMA control, while lower loadings of CNCs and all loadings of PMMA‐g‐CNCs did not. The difference in Young's modulus between unmodified CNC and polymer‐grafted CNC composites was generally insignificant. Overall, ball‐milled composites had inferior mechanical and rheological properties compared to melt‐mixed composites. Scanning electron microscopy showed aggregation in the samples with CNCs, but more pronounced aggregation with PMMA‐g‐CNCs. Despite improving interfacial compatibility between the nanoparticles and the matrix, the effect of PMMA‐g‐CNC aggregation and decreased thermal stability dominated the composite performance.     

Heavy crude oil asphaltenes as a nanofiller for epoxy resin

Asphaltenes are harmful components of heavy crude oils and require rational utilization after oil refining or deasphalting. Asphaltenes are macromolecules containing various functional groups that self-assemble to nanoscale aggregates and can be used as nanofillers for polymers. In this research, mixtures of asphaltenes with the diglycidyl ether of bisphenol A were considered. The solubility of asphaltenes in this epoxy resin, the rheological properties of the mixtures, and the effect of asphaltenes on the curing with 4,4′-diaminodiphenyl sulfone were studied. In addition, the glass transition temperature, strength, and adhesion characteristics of the asphaltene-filled cured composites were evaluated. The dual role of asphaltenes in polymer modification was demonstrated: the asphaltenes simultaneously plasticize and reinforce the polymer matrix, and the transition from predominant plasticization to strengthening occurs with an asphaltene content at 20 wt%. The dual reinforcement/plasticization effect occurs because epoxy composites contain both nanosized and microsized particles of asphaltenes due to the partial dissolution of asphaltenes in the epoxy resin and the decrease in their solubility during high-temperature curing.     

Compatibility and biodegradability of blendsof starch cinnamate with various polymers

The compatibility of blends of starch cinnamate (StCn) with polyvinyl chloride (PVC), polystyrene (PS), and styrene acrylonitrile copolymer (SAN) has been examined through viscometry at 30°C. The results of the three systems are compared with the already reported PMMA/StCn system. From the intrinsic viscosity, relative viscosity, reduced viscosity, and density measurements the PVC/StCn and SAN/StCn blends were found to be compatible while PS/StCn blend was found to be incompatible. The compatibility of the blends was also confirmed by SEM analysis. The compatibility of these blends based on heat of mixing and polymer-polymer interaction parameter was also examined. Blends were observed to be compatible on the basis of heat of mixing theory but not on the basis of polymer - polymer interaction parameters. Biodegradation studies of compatible blends containing 30% StCn showed 13%, 15%, 18%, and 23% weight loss in case of PMMA, SAN, and PVC blends after 120 days.     

Influence of polarity on the preferential intercalation behavior of clay in immiscible polypropylene/polystyrene blend

The immiscible polypropylene (PP)/polystyrene (PS) blend was prepared via melt compounding and the preferential intercalation behavior of clay was investigated by wide angle X‐ray diffraction (XRD) and transmission electron microscope (TEM). It was found that the clay platelets initially located in the PS phase in PP/PS/Clay composites and PS chains intercalated into the clay layers. However, all clay migrated from the PS phase to the modified PP phase after introducing polar maleic anhydride group (MAH) to PP chains. Interestingly, most of clay migrated from the modified PP phase to the modified PS phase again when PS matrix was modified with sulfonic group, and some enriched in the interphase region. The interaction energy density (B) of the blends was determined by combining the melting point variation with the ternary interaction model for heat of mixing. It was found that the value of B decreased with the introduction of polar group (MAH or sulfonic group), indicating that the polarization of PP and PS can enhance interaction between clay platelet and polymer component. Different interaction between clay platelet and polymer component leads to the preferential intercalation behavior. The higher polarity of the polymer generates higher interaction between clay and polymer component as well as results in stronger preferential intercalating ability. Moreover, the results of FTIR spectra after extraction of all samples gave additional explanation of the preferential intercalation behavior of clay in the immiscible PP/PS blends. On the basis of the results of the measurement mentioned above, a possible mechanism was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

High‐performance soluble copolyarylate based on phenolphthalein: synthesis,characterization and properties

A series of copolyarylates (PP0–PP100) containing phthalide groups was synthesized via interfacial polymerization from a mixture of phenolphthalein (PP) and bisphenol A with molar equivalent of terephthalyl chloride. Incorporating PP into the polymer chain improved the solubility of the polyarylates in common organic solvents. The glass transition temperature (191–314 °C), residual weight percentage, Young's modulus (1.7–2.8 GPa), solubility and complex melt viscosity of the copolyarylates increased with increasing PP units in the copolymerization. By contrast, crystallinity and elongation at break (14.1 to 11.2%) of the copolyarylates decreased with increasing PP units in the polymer backbone. When the PP content increased over 30 mol% (PP30), the copolyarylates became amorphous polymers. When the PP content was below 30 mol%, the copolyarylates exhibited good melt processability. With regards to its solubility, thermal stability, mechanical properties and melt processability, PP30 may be considered as a promising candidate in the field of processable high‐performance engineering plastics. © 2019 Society of Chemical Industry     

超高分子量聚乙烯对有机PTC复合材料的超强稳定作用研究

利用传统的熔融 混合方法制备碳黑填充的聚丙烯 (PP) /超高分子量聚乙烯 (UHMWPE)复合物。当PP/UHMWPE混合比大于 3 / 7,碳黑填充PP/UHMWPE复合物的PTC和NTC效应类似于碳黑填充的纯净PP聚合物。然而当重量比等于或小于 3 / 7时 ,复合物所表现的PTC效应非常相似于碳黑填充的纯净的UHMWPE聚合物。在复合物中应用粘度非常高的聚合物作为一种组分可以有效消除NTC效应     

Highly conductive, melt processable polymer composites based on nickel and low melting eutectic metal

Highly conductive polymers are difficult to process utilizing standard polymer approaches. This report describes a polymer composite loaded with a eutectic metal that is molten during melt processing along with a more traditional Nickel particulate filler. Conductivities over 300 S/cm were achieved, and 60 vol% metals loading was processable with a single screw extruder. The addition of the Nickel particulate was critical for maintaining eutectic dispersion. We anticipate that this approach will facilitate the implementation of conductive polymers into a broader variety of practical applications, due to the enhanced compatibility with standard polymer processing techniques such as extrusion, melt mixing, and resin transfer-molding operations.     

UHMWPE对有机PTC复合材料的稳定作用

利用传统的熔融－混合方法制备碳黑填充的聚丙烯（PP）／超高分子质量聚乙烯（UHMWPE）复合材料,当P／UHMWPE质量比大于3／7时,碳黑填充PP／UHMWPE复合物的正温度系数（PTC）和负温度系数（NTC）效应类似于碳黑填充的纯PP聚合物,但当质量比等于或小于3／7时,复合物所表现的PTC效应非常相似于碳黑填充充的纯UHMWPE聚合物,在复合物中采用粘度非常高的聚合物作为一种组分可以有效消除NTC效应。     

PP/PS/纳米插层高岭土复合材料的制备及性能研究

采用熔融共混法制备了聚丙烯/聚苯乙烯/二甲基亚砜插层改性高岭土（PP/PS/K-DMSO）复合材料。研究了不同用量K-DMSO对PP/PS共混材料的结构及性能的影响。结果表明,随着K-DMSO的加入,复合材料的加工性能、力学性能、热性能均得到提高;与PP/PS共混材料相比,在K-DMSO的加入量为6 %（质量分数,下同）时,熔融流动速率增加了2.925 g/(10min),冲击强度提高了48.8 %,弯曲强度提高了24.1 %。扫描电镜分析表明,K-DMSO的加入,使PP与PS两相界面模糊,PS分散相尺寸减小,增加了PP、PS的相容性。     

Optical properties of particle‐filled polycarbonate,polystyrene, and poly(methyl methacrylate) composites

Transparency is a key material property of polycarbonate (PC), polystyrene (PS), and poly(methyl methacrylate) (PMMA). To study the optical properties of particle‐filled PC, PS, and PMMA, composites containing inorganic particles in different sizes and concentrations were produced by direct melt mixing in this work. The optical properties characterized by total light transmittance, haze, and clarity were studied. The results show that the optical properties of polymer composites are strongly affected by particle content, particle size, and especially by difference in refractive indices between polymer matrix and particles. It is also revealed that the light transmittance and haze of composites are mainly affected by difference in refractive indices, whereas the clarity is more affected by particle size. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Melt rheology and morphology of physically compatibilized natural rubber–polystyrene blends by the addition of natural rubber-g-polystyrene

Blends of natural rubber (NR) and polystyrene (PS) were prepared by melt mixing in a Brabender plasticorder and by solution casting using chloroform as the casting solvent. Earlier studies have indicated that these blends are incompatible and immiscible, and their compatibility can be improved by the addition of a graft copolymer of NR and PS (NR-g-PS). The rheological behavior of these blends has been carried out in the presence and absence of the compatibilizer using a capillary rheometer and a melt flow indexer. The effects of blend ratio, processing techniques (melt mixing versus solution casting), shear stress, and temperature on the rheological behavior have been studied in detail. Both in the presence and absence of the copolymer, the blends showed a decrease in viscosity with an increase of shear stress, indicating pseudoplastic nature. Solution-cast blends showed a higher viscosity as compared to melt-mixed blends. The viscosity versus composition curve of both melt-mixed and solution-cast blends showed negative deviation from the additivity at a higher shear rate region. This is associated with the interlayer slip between the highly incompatible NR and PS phases. The effects of graft copolymer loading and temperature on solution-cast blends were studied, and it was found that as the copolymer loading increases, the shear viscosity increases. This is due to the high interfacial interaction between the two components in the presence of the copolymer. The copolymer, in fact, locates at the interface and makes the interface more broad. However, at higher loading of the copolymer, the viscosity of the blends decreases. This may be associated with the formation of micelles, which have a plasticizing action on the viscosity of the blends. Melt elasticity parameters like principal normal stress difference, recoverable elastic shear strain, and die swell were evaluated. Master curves have been generated using modified viscosity and shear rate functions that contain the melt flow index as a parameter. The extrudate morphology of the blends was studied using a scanning electron microscope. Addition of the copolymer reduces the domain size of the dispersed phase, followed by a leveling off at a higher concentration. The leveling off is an indication of interfacial saturation. The interparticle distance also decreased followed by a leveling off at a higher loading of the copolymer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2673–2690, 1998     

In situ reactive compatibilization in polymer blends: Effects of functional group concentrations

Polystyrene (PS) and polyethylene (PE), along with their reactive counterparts, i.e., polystyrene having oxazoline reactive groups (OPS) and polyethylene with carboxylic acid groups (CPE), were melt blended in a Rheomix mixer. These blends were prepared by mixing these polymers in various proportions under a variety of conditions. In an alternate procedure the OPS, CPE graft polymer (OPS-g-CPE) was prepared by melt blending these two polymers beforehand, and subsequently this grafted polymer was used as a compatibilizer for PS–PE blends. The effects of the addition of OPS and CPE, on the one hand, and OPS-g-CPE, on the other hand, on the compatibility of PS–PE blends were investigated. The morphology of these blends was examined with a scanning electron microscope (SEM) and related to their tensile properties. The PS–PE blends are found to have the typical coarse morphology of incompatible blends and poor tensile properties while their reactive counterparts, OPS-CPE blends, have fine grain microstructure and show improved tensile strength throughout the range and improved elongation in the PE-rich blends. Relatively low concentrations of the reactive pair, oxazoline and carboxylic acid, are shown to be necessary to produce improved compatibility. The preblended graft copolymer OPS-g-CPE imparts compatibility to PS–PE blends also but not as effectively. This suggests that the addition of OPS and CPE during melt mixing of PS and PE forms OPS-g-CPE polymer at the interface and that these ingredients act as “in situ reactive compatibilizers” which improve physical properties.     

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。     

Melt compounding of various polymers with organoclay by shear flow

We studied melt compounding of polymer/organoclay composites by shear flow in a rotating cylindrical mixer to investigate an effect of shear stress on the dispersion state of clay. The commercial organoclay, which is intercalated by dimethyl benzyl stearyl ammonium ion between clay platelets, and four kinds of commercial polymer (polystyrene (PS), poly(lactic acid) (PLA), polyamide(PA6), and poly(butylene succinate) (PBS)) were used in this study. According to the TEM photographs, there is exfoliated clay in PA6/organoclay composite, but the exfoliated clay cannot be seen in other polymer/organoclay composites. We calculated the value of clay dispersion from the low magnification TEM photograph, called the dispersion coefficient to consider the micro level dispersion of the clay in a polymer matrix. Generally, the dispersion coefficient increases with shear stress. However, the dispersion coefficients in case using PA6 and PBS as the matrix, whose melts have low viscosity, are larger than those in case using PS and PLA, whose melts have high viscosity. According to XRD results, d₀₀₁ peak originated from organoclay mostly shifted to the low value of angle for PA6/organoclay composite and began shifting to the low value of angle for PBS/organoclay composite. However, there is a peak for PS and PLA based organoclay composites. From the cases of PA6 and PBS in the DMA results, the storage modulus increases with an addition of organoclay. These results imply that low viscosity polymer is typical easy to get the composites with intercalated clay by melt compounding. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Morphological properties,rheological behaviors,and phase interaction of nylon 11/polypropylene blends by in situ reactive compatibilization and dispersion through polyhydroxybutyrate

The current research discusses the reactive compatibilization of nylon 11 (PA11) and polypropylene (PP) using maleic anhydride grafted PP (PP-g-MA) through an extruder. PP phase is dispersed in PA11 by coalescence and droplet break-up mechanism by using polyhydroxybutyrate (PHB) as a dispersion agent that induces uniform interaction between the blend components. The reactive compatibilization ensures the mixing of polymers, and the consistent interaction of phases is controlled by dispersion. All of the blends were processed through melt processing at different compositions using a twin-screw extruder. Scanning electron microscopy was used to determine the morphologies of the binary and ternary blends. Surface tension and interfacial tension of the homopolymer characterizes the interaction of the polymers at interphase. The interaction of PHB/PA11 appeared preferable than that of PHB/PP, elaborating on the efficient dispersion and droplet formation of the PP phase. The compatibilizer maleic anhydride grafted PP (PP-g-MA) imparts a drastic effect on the compatibility of PA11-PP and PA11-PHB-PP blends and reduces PP phase particle size, which indicates the affinity of PHB and PP. The encapsulation of PP by PHB was seen in the expectation of minimum free energy models. The rheological measurements were used to understand the phase separation within blends. These measurements were also applied to understand the interaction between PA11-PP-PHB phases. The modulus values and viscosity ratio of the blends were measured to follow the chain relaxation in the melt. In the Cole–Cole plot, it was found that the reduction in PP phase size influences the relaxation of chains of blends.     

微纳米有机微球对聚丙烯复合体系流变及力学性能的影响

用聚丙烯和马来酸酐接枝聚丙烯作为基体,以微乳液法制备的纳米微球作为添加剂制备出3种不同的复合体系,并通过旋转流变仪对各复合体系与聚丙烯／马来酸酐接枝聚丙烯基体的流变行为进行了对比研究,然后通过电子万能试验机对各复合体系以及基体的力学性能进行了对比试验。结果表明：随着纳米微球的加入,复合体系的表观黏度均下降;同时,随着剪切速率和剪切应力的增加,各复合体系的表观黏度也下降。由此可推得,纳米微球的加入可以在相对较低的温度下降低熔体黏度,更加有利于纺丝成形。通过研究,3#微球较其他样品具备较优的熔融纺丝条件,且力学性能下降也最少。     

Influence of wrapping on some properties of MWCNT–PMMA and MWCNT–PE composites

The melt processing technique was used to elaborate composites made with a polymer matrix [polymethylmethacrylate (PMMA) or polyethylene (PE)] and multiwall carbon nanotubes (MWCNT). Nanotubes were wrapped by amphiphilic block copolymer (PE–co-polyethylene oxide) in aqueous solution to facilitate the dispersion and the handling. Morphology and physical properties (thermal, mechanical, electrical, and rheological) of the resulting composites were investigated. The wrapping of MWCNT allowed a good dispersion of these nanoparticules in the polymer matrices. Physical properties such as thermal degradation, mechanical behavior, and conduction are improved. The use of wrapped MWCNT allows to reduce drastically the melt viscosity of the blends of crystalline PE composites whereas it is almost non efficient for amorphous PMMA ones.