Carbon Black Dispersion Research Articles

Chemical analysis applied to the development of a model for the determination of quality of PE pipes

The aim of this work is expanding the base of data on which a previous developed method of predicting polyethylene (PE) quality was based. The refined method will provide water companies with a simple way of assessing chemical differences that may occur among PE pipes due to different manufacturers or different batches of virgin polymer. A number of samples, taken from PE water-ducts, were pyrolysed (triplicate analyses) at 700 °C in N 2 atmosphere using a platinum coil pyrolyser inside a tube cooled in liquid nitrogen. The volatile and non-volatile products were identified and quantified by gas chromatography/mass spectrometry, and subjected to discriminant analysis. The same samples were also pyrolysed at 900 °C in order to analyse high molecular weight pyrolysis products. Moreover, polycyclic aromatic hydrocarbons and volatile organic compounds leaching from PE tubes into drinking water were determined. Data acquired were matched up with results obtained using physical methods of polymer characterisation, namely density, oxidative induction time, melt flow rate and carbon black dispersion.

Study on the structure and properties of SSBR with large-volume functional groups at the end of chains

Solution polymerized styrene-butadiene rubber (SSBR) and SSBR with tert-Butylchlorodiphenylsilane (TBCSi, large-volume functional groups) at the two ends of macromolecular chains (T-SSBR) were prepared by anionic polymerization. The molecular structure parameters of T-SSBR and SSBR were characterized and the ratio of the amount of macromolecular chain ends connected with TBCSi to total macromolecular chain ends (i.e., end-capping efficiency) was calculated. The comprehensive properties of T-SSBR and SSBR composites filled with carbon black (CB) were investigated. The results showed that T-SSBR composites presented lower Payne effect (namely better CB dispersion) than those of SSBR composites, which led to decrease in hardness, internal friction, dynamic compression heat built-up and permanent set of T-SSBR composites, significant increase in tensile strength, elongation at break, tear strength and resilience of T-SSBR composites, and excellent balance between wet-skid resistance and rolling resistance. However, compared with SSBR composites, T-SSBR composites presented longer stress-relaxation time, bigger die-swell and higher apparent viscosity, as well as slightly inferior dynamic-cutting resistance. All the above, owing to the end-capping of TBCSi, which could immobilize the free chain ends of T-SSBR (i.e., to reduce the friction loss of molecular chains and create a greater degree of orientation in the force field), and adsorb CB, the comprehensive performances of T-SSBR were better than those of SSBR and T-SSBR terminated with styrene-TBCSi (TS-SSBR) were far superior to those of T-SSBR terminated with butadiene-TBCSi (TB-SSBR). Accordingly, the former was suitable for the tread of green tires.

Effect of surface modifications of carbon black (CB) on the properties of CB/polyurethane foams

The effect of surface modifications of carbon black (CB) on its dispersion in polyether polyol and CB/polyurethane (PU) foams and the properties of the CB/PU composite foams was investigated. Pristine CB (p-CB) was oxidized in nitric acid to obtain oxidized CB (o-CB), and then by the esterification reaction between the carboxyl groups of o-CB and the hydroxyl groups of polyether polyol, polyol grafted CB (g-CB) was obtained. Optical microscopy, scanning and transmission electron microscopy observations showed that surface modifications effectively improved the dispersion of CB in polyether polyol and in the final composite foams. Compared with the p-CB/PU foams, the o-CB/PU and g-CB/PU composite foams exhibited improved conductivities, storage moduli, and increased glass transition temperatures. The compressive strengths of the p-CB/PU and o-CB/PU composite foams decreased with the increase of filler contents, but g-CB has no negative effect on the compressive strength even at a filler content as high as 8 phr. Furthermore, the cell sizes for the o-CB/PU and g-CB/PU composite foams were more uniform than those of p-CB/PU foams.

Electrophoretic mobility of concentrated carbon black dispersions in a low-permittivity solvent by optical coherence tomography

Electrophoretic mobilities of concentrated dispersions of carbon black particles in a low-permittivity solvent were measured using differential-phase optical coherence tomography (DP-OCT). An electrode spacing of only 0.18 mm enables measurement of highly concentrated dispersions up to 1 wt.% of highly absorbing carbon black particles with high electric fields at low potentials. The capabilities of this DP-OCT method, including high sensitivity, high spatial resolution, and strong electric fields, enable enhanced measurement of low electrophoretic mobilities encountered in low-permittivity solvents. The zeta potential of carbon black particles ranged from −24 mV to −12 mV as the concentration of surfactant sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT) was increased from 1 mM to 100 mM. A mechanism is presented to explain the electrostatic charging of carbon black particles in terms of the partitioning of the ions between the reverse micelles in the double layer and the surfactant adsorbed on the particle surface, as AOT concentration is varied.

High performance electrochemical sensor based on modified screen-printed electrodes with cost-effective dispersion of nanostructured carbon black

Abstract A novel sensor based on a screen-printed electrode (SPE) modified with a stable dispersion of commercially available carbon black (CB) N220 was developed. This probe showed significantly enhanced electrochemical activity relative to a bare SPE when tested with ferricyanide, epinephrine, norepinephrine, benzoquinone and NADH. When challenged in amperometric batch mode with NADH, the response was stable and revealed a linear dependence up to 2·10−4 mol L−1 with a detection limit of 3·10−7 mol L−1. The analytical performance, coupled with the low cost of the CB nanomaterial, suggests that this sensor holds promise for electrochemical applications.

Influence of In-situ Grafting on the Dispersion of Carbon Black in Solvents and Natural Rubber

In-situ grafting of natural rubber (NR) onto the carbon black (CB) surface by a solid-state method was used to obtain grafted carbon black (GCB). The morphology of the original CB and GCB particles was observed by AFM and TEM. The original CB particles fused together and occurred as large dendritic agglomerates while the GCB particles occurred as small aggregates about 150 nm in diameter. The dispersion and dispersion stability of CB and GCB in toluene and cyclohexene were studied by zeta potential and a spectrophotometer. The results showed that the grafting procedure can improve both dispersion and dispersion stability of CB particles. The dispersion in NR was studied by DMA and observed by SEM. It was shown that GCB has better dispersion than CB in a NR matrix. As expected a weakened filler-filler interaction and enhanced filler-polymer interaction occurred after grafting modification.

Vibration damping and electrical conductivity of styrene–butyl acrylate random copolymers filled with carbon black

AbstractEmulsion‐polymerized poly(styrene‐rand‐butyl acrylate) (St–BA) copolymers exhibit damping capabilities over a wide temperature range with changes in the monomer ratio. Blending copolymers of different compositions results in a multidamping peak, further widening the effective damping temperature range. Adding carbon black (CB) reduces the peak damping intensity but enhances damping at higher temperatures. The addition of dodecyl benzene sulfonic acid to an St–BA/CB aqueous dispersion improves the dispersion of CB in the polymer, reducing the percolation threshold and improving the conductivity while slightly affecting the mechanical behavior. The electrical properties of the St–BA/CB system are affected by the copolymer composition, influencing the polymer surface tension. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Positive Temperature Coefficient Behavior of HDPE/EVA Blends Filled with Carbon Black

The electrical resistivity and positive temperature coefficient (PTC) behavior of carbon black (CB)-filled high density polyethylene (HDPE) /ethylene-vinyl acetate copolymer (EVA) composites were investigated. At any particular CB content, the composite with the HDPE/EVA weight ratio 9/1 showed the lowest resistivity compared to other composites under investigation. The resistivity was decreased after the addition of small amount of EVA in HDPE with a particular CB loading. This is due to the improvement in dispersion of CB in HDPE in presence of small amount of EVA. However, the resistivity was again increased after the addition of higher amount of EVA due to the formation of an insulation polymer shield by EVA around CB particles. The nature and intensity of PTC was dependent on the HDPE/EVA ratio. With the increase in EVA content, PTC was shifted at a lower temperature. The highest PTC intensity was observed for the composite with HDPE/EVA ratio 8/2.

Synergistic Effect of TNPP and Carbon Black in Weathered XLPE Materials

Carbon black is one of the most widely used and most effective ultraviolet (UV) light stabilizers for plastics applications. Several important segments of the plastics industry rely on carbon black for UV stabilization of weather-resistant products, including telecommunications, power cable jacketing, and plastic pipes. In this research work a combination of Trisnonylphospate (TNPP) antioxidant and different size carbon black were applied in crosslinked polyethylene (XLPE) to improve its wetherability. The primary reason for cross-linking polyethylene (PE) is to raise the thermal stability of the material under load. This substantially improves environmental stress crack resistance and resistance to slow crack growth. The results achieved of this additive package combination show a synergism effect and improved weatherability of electrical cable. Increased weathering lifetime was also achieved. Further, we were able to confirm in this work, that the size and quality of the carbon black dispersion in a XLPE samples is an important component of both the UV-resistance and mechanical properties of the finished plastic article. Incremental improvements of carbon black dispersion can positively influence the expected life of plastic articles. Mechanical testing and FTIR were used to detect degradation of the accelerated weathered XLPE samples. The morphological considerations of UV energy absorption and presents laboratory data demonstrating the link between dispersion and weatherability as well as between morphology and weatherability

Dispersion and stability of carbon black nanoparticles, studied by ultraviolet–visible spectroscopy

The dispersion and stability of carbon black (CB) nanoparticles in water were investigated using ultra-violet–visible (UV–vis) spectroscopy. After studying the effects of five dispersants, the most appropriate ones, Triton X-100 and N220 CB, were selected. UV–vis spectra of samples containing different amounts of Triton X-100 and a constant amount of CB were used to find the optimal circumstances of CB dispersion. Also, the stability of the dispersion was studied and it was found that the optimum conditions could be achieved in colloidal mixture containing CB and Triton X-100 in a weight ratio of 2:1. It was clarified that the mixtures containing Triton X-100 up to 50 wt% CB were stable over a period of 20 days. In order to support the UV–vis results additional techniques such as AFM, PSA and FE-SEM were employed.

Characterization of the effect of the filler dispersion on the stress relaxation behavior of carbon black filled rubber composites

In the present work a new evaluation method for the characterization of the stress relaxation behavior of rubber–carbon black (CB) composites is presented. Using the chart of the online measured electrical conductance received from the recording equipment in the mixing chamber different rubber–CB composites with well defined state of the CB network have been produced for the stress relaxation investigation. The development of CB dispersion degree and the rubber-layer bonded on the CB surface have been characterized systematically using the method of the online measured electrical conductance and the thermogravimetric analysis of rubber–filler gel. The analysis of the stress relaxation curves is based on the division of the initial stress into several stress components and the consideration of the structure of the composites as a combination of different networks. The contribution of the stress component to the corresponding network is the focus of the present work. Based on the systematic variation of material parameters and test conditions we could divide the applied stress into six stress components which are originated from the rubber matrix and CB. It is obvious that the debonding of the rubber-layer from the CB surface and the collapse of a part of the CB network can be described by the relaxing stress component ΔσCB(rubber-layer) and ΔσCB(network), respectively. The non-relaxing stress components σ∞CB(rubber-layer) and σ∞CB(network) are dependent on the amount of the time-stable bonding in the rubber-layer and the stable part of the CB network. The mechanical performance of the composites and especially the time and temperature dependent mechanical behavior could be specifically modified by CB addition.

Determination of the Degree of Dispersion of Carbon Black in Rubber Mixes

Determination of the Degree of Dispersion of Carbon Black in Rubber Mixes

Effect of Dispersion of Carbon Black on Electrical and Thermal Properties of Poly(Ethylene Terephthalate)/Carbon Black Composites

A type of grafted carbon black (GCB), prepared with a low molecular weight antioxidant compound by in-situ reaction, was dispersed in poly(ethylene terephthalate) (PET) by a melt-blending process. Dispersion of fillers, volume resistivity, and thermal properties were investigated using scanning electron microscopy, a high-resistance meter, differential scanning calorimetry, and thermogravimetric analysis, respectively. The results show that, compared with carbon black (CB) particles, GCB particles dispersed better in the PET matrix, whereas the conductivity percolation threshold of PET/GCB was higher than that of PET/CB. The addition of GCB or CB elevated the cold crystallization temperature of PET, reflecting the effectiveness of carbon fillers as nucleating agents. But carbon fillers decreased the crystallization enthalpy of PET during both heating and cooling process. Both CB and GCB elevated the starting temperature of thermal degradation of PET and increased the amount of residues for the composites over that of neat PET.

A novel dispersant for preparation of high loading and photosensitive carbon black dispersion

AbstractHigh loading of stable carbon black (CB) dispersion in organic solvent, PGMEA, was prepared by a ball‐milling process when using poly(styrene‐EHA‐HEMA)‐block‐poly(styrene‐EHA‐HEMA‐DMAEMA) (P(SEH)‐b‐P(SEHD)) as a dispersant. The P(SEH)‐b‐P(SEHD) containing P(SEH) as a steric chain and P(SEHD) as an anchoring chain was prepared by TEMPO‐mediated polymerization. The tertiary amine group of DMAEMA in P(SEHD) chain could be adsorbed onto CB by the interaction with the carboxylic acid group on surface of CB and the P(SEH) chain could provide sufficiently steric repulsion force to avoid the aggregation of CB. In addition, a photosensitive dispersant, P(SEH)‐b‐P(SEHD)CC, containing the methacrylate double bond side group was also synthesized and was used to prepare stable CB dispersion in PGMEA. The effects of the molecular weight between steric and anchoring chains, the content of tertiary amine, and the amount of methacrylate double bond in the dispersant on the particle size of CB were investigated. Furthermore, the influences of various surface properties of CB, such as specific surface area, content of carboxylic acid group, and size of primary particle, on the particle size of CB in dispersion were also discussed. Finally, the photosensitivity of P(SEH)‐b‐P(SEHD)CC/CB composite was monitored by a photodifferential scanning calorimeter. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6185–6197, 2008

AN INVESTIGATION OF DISPERSION AND STABILITY OF CARBON BLACK NANO PARTICLES IN WATER VIA UV-VISIBLE SPECTROSCOPY

Study of the quality of carbon black dispersion by using UV-Visible Spectroscopy was carried out. Carbon materials have a main absorption around 200 nm (UV region) due to π→π* excitation. Based on UV absorption of carbon black and the parameter affects the absorption, UV Visible spectroscopy was used to study CB dispersion. Result showed that Triton X-100 was proper kinds of dispersant which resulted in higher UV absorption compared to other used dispersants. Also proper weight ratio of Triton X-100 to initial carbon solid was calculated of 50 wt% which no significant change was observed for sample containing higher amount of dispersant. Finally AFM images and PSA results asserted the results obtained from UV-Visible Spectroscopy.

Fine dispersion of carbon black in fluorene‐based resin

AbstractThe dispersion ability of fluorene‐based epoxy resin (FBE), bisphenol A based epoxy resin (PBE), fluorene‐based polyester (FBP), and polycarbonate (PC) in carbon black (CB) was evaluated. CB/FBE composite had a lower L value (reflectance, blackness) than that of CB/PBE composite, for the same CB content. Aggregations of CB in CB/FBE composites were much smaller than those in CB/PBE composites. The strong interaction between fluorene with cardo structure and CB resulted in a fine dispersion of CB in FBE. FBP had much higher dispersion ability of CB than PC. CB (50 wt%) was dispersed into FBP compared with the 10 wt% of CB dispersed in PC by melt blending. The effect of CB on the mechanical properties of FBP was much higher than that on PC due to fine dispersion of CB in FBP. The effect of CB addition on the Tg of FBP was also higher than that of CB on the Tg of PC. Computational simulation indicates that most stable energy between fluorene with a cardo structure and graphite structure was smaller than the energy between bisphenol A and graphite. It was also shown that the minimum energy appeared when the fluorene structure was almost parallel to the graphite plane. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

Ultrafiltration of Humic Acid Solution: Effects of Self‐dispersible Carbon Black and Cations

Effects of carbon black (CB) addition on membrane fouling and rejection of macromolecular humic acids (HA) were evaluated by a stirred‐cell ultrafiltration unit. Stable CB dispersions increased filtration resistances, but enhanced HA rejection by the membranes. Monovalent and divalent ions affected the filtration resistance of CB solution differently; namely, NaCl solution showed a very high resistance due to the concentration of CB in the diffusion boundary layer near the membrane surface, whereas CaCl2 and MgCl2 solutions showed only cake resistance. The cake layer containing both CB and HA was more easily removed from the membranes than HA‐cake layer.

The mastication characteristics of powdered carbon black filled natural rubber during internal mixing

AbstractPowdered carbon black filled natural rubber, P(NR/HAF), is a premixture of natural rubber and carbon black in powdered form with good carbon black dispersion throughout the rubber matrix. In this study, the mastication properties of P(NR/HAF) were observed under a wide temperature range (50–110°C) and rotor speed (30–100 rpm) range, using a mixing head attached to Brabender Plasticorder. It was found that P(NR/HAF) showed different mastication characteristic, compared to the traditional internal mastication theories of natural rubber; poor masticating properties of P(NR/HAF) are observed with low rotor speed and high temperature and a ‘‘stable zone’’ with middle rotor speed and lower temperature. The Mooney viscosity of rubber batch under different rotor speed and temperature was almost the same, and mastication properties were unsatisfactory. It was considered that the higher temperature build‐up of the mixing batch of P(NR/HAF) during the early stage of internal mixing results in the special mastication properties. A quadratic mastication model of P(NR/HAF), based on the multivariate regression analysis and stepwise regression analysis, was used to predict the mastication characters of P(NR/HAF) in internal mixer under varied temperature and rotor speed. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Electrical and Mechanical Properties of Carbon Black -Filled Poly (Styrene-Co-Butyl Acrylate) Latex Reinforced Polyester Nonwoven Composites

The main goal of the present research work was to fabricate lightweight nonwoven fabric impregnated composites for antistatic applications. Composites were fabricated by impregnating polyester nonwoven fabric with aqueous carbon black (CB) filled poly (styrene-co-butyl acrylate) latex. The effect of the amount of CB on the mechanical and electrical properties has been studied. Tensile strength, stitch tear strength and surface hardness were reduced by an increase in the wt.% of CB. The percentage elongation of the composites increased drastically because of the presence of diethylene glycol plasticiser in the CB dispersion. The dielectric constant, dissipation factor and loss factor of the composites increased with increasing wt.% of CB and decreased with increasing frequency. The reduction in dielectric properties with increasing frequency could be due to the delocalisation of charge carriers.

Dynamic mechanical properties of styrene-butadiene composites reinforced by defatted soy flour and carbon black co-filler

Carboxylated styrene-butadiene (SB) com- posites reinforced by a mixture of defatted soy flour (DSF) and carbon black (CB) were investigated in terms of their dynamic mechanical properties. DSF is an abundant renewable commodity and has a lower cost than CB. DSF contains soy protein, carbohydrate, and whey. Aqueous dispersions of DSF and CB were first mixed and then blended with SB latex to form rubber composites using freeze-drying and compression molding methods. At 1408C, a single filler composite reinforced by 30% DSF exhibited roughly a 230-fold increase in the shear elastic modulus compared to the unfilled SB rubber, indicating a significant reinforcement effect by DSF. Mixtures of DSF and CB at three different ratios were investigated as co- fillers. Temperature sweep experiments indicate the shear elastic moduli of the co-filler composites are between that of DSF and CB composites. Strain sweep experiments were used to study the fatigue and recovery behaviors of these composites. Compared with the DSF composites, the re- covery behaviors of the 30% co-filler composites after the eight consecutive deformation cycles of dynamic strain were improved and similar to that of 30% CB composite. Strain sweep experiments also indicated that the co-filler composites have a greater elastic modulus than the CB re- inforced composites within the strain range mea- sured. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 108: 65- 75, 2008