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1.
Small‐angle X‐ray scattering (SAXS) studies of electrically conductive blends based on polyaniline–dodecylbenzenesulfonic acid (PANI–DBSA)/styrene–butadiene–styrene (SBS) triblock copolymer were performed to investigate the influence of the blend preparation procedure on the nanoscopic structure of the blends. The blends were prepared by mechanical mixing (MM) procedure and by in situ polymerization (ISP) of aniline in the presence of SBS. The results indicate that pure PANI–DBSA presents an extended phase consisting of crystalline islands of nanometric size, with a good spatial correlation between them, embedded into an amorphous PANI phase. This feature was not observed in SBS/PANI–DBSA blends prepared by MM or ISP. In MM blends, the PANI phase is constituted by smaller domains, containing poorly spatially correlated crystalline islands, whereas in ISP blends with low or medium amount of PANI, there is no SAXS peak which could be related to a spatial correlation between PANI crystalline islands. The conductivity of the ISP blends is higher when compared to MM blends because of the higher homogeneity at nanometric scale. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3069–3077, 2007  相似文献   

2.
In this work, the influence of polyaniline (PAni) doped with both camphorsulfonic acid (PAni‐CSA) and dodecylbenzenesulfonic acid (PAni‐DBSA) on polyurethane (PU)/PAni blends was studied by rheological and morphological analyses. The effect of doped polyaniline on the attenuation of incident microwave radiation, in the frequency range from 8.0 to 12.0 GHz, was also investigated. The complex viscosity (η*) of PAni‐DBSA blends is observed to vary more significantly as a function of resting time than PAni‐CSA blends. This behavior is attributed to a better dispersion of PAni particles into the matrix on account of the presence of smaller agglomerates, as observed by optical and electron microscopy. However, this behavior has not been determinant on microwave absorption by the blends, with those that contain PAni‐CSA showing higher attenuation values. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

3.
This article describes electrically conductive polymer blends containing polyaniline‐dodecyl benzene sulfonic acid (PANI‐DBSA) dispersed in a polystyrene (PS) matrix or in crosslinked polystyrene (XPS). Melt blending of previously mixed, coagulated, and dried aqueous dispersions of PANI‐DBSA and PS latices lead to high conductivities at extremely low PANI‐DBSA concentrations (∼0.5 wt % PANI‐DBSA). In these blends, the very small size of the PANI‐DBSA particles and the surface properties (with surfactants used) of both the PANI and polymer particles play a major role in the PANI‐DBSA particle structuring process. The PANI‐DBSA behavior is characteristic of a unique colloidal polymeric filler with an extremely high surface area and a strong interaction with the matrix, evidenced by a significantly higher glass‐transition temperature of the matrix. The effect of the shear level on the conductivity and morphology of the PS/PANI‐DBSA blends was studied by the production of capillary rheometer filaments at various shear rates. An outstanding result was found for XPS/PANI‐DBSA blends prepared by the blending of aqueous XPS and PANI‐DBSA dispersions. Some of these blends were insulating at low shear levels; however, above a certain shear level, smooth surface filaments were generated, with dramatically increased and stable conductivities. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 611–621, 2001  相似文献   

4.
Small-angle neutron scattering (SANS) has been employed to study a blend of polystyrene and polybutadiene modified by copolymer additives. SANS data from the one-phase region approaching the phase boundary has been acquired for blends modified by random and diblock copolymers that have equal amounts of styrene and butadiene monomers as well as a random copolymer with an unequal monomer composition. The binary blend is near the critical composition, and the copolymer concentrations are low at 2.5% (w/w). The data have been fitted with the random-phase approximation model (binary and multicomponent versions) to obtain Flory–Huggins interaction parameters (χ) for the various monomer interactions. These results are considered in the context of previous light scattering data for the same blend systems. The SANS cloud points are in good agreement with previous results from light scattering. The shifts in the phase boundary are due to the effects of the additives on the χ parameter at the spinodal. All the additives appear to lower the χ parameter between the homopolymers; this is in conflict with the predicted Flory–Huggins behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3191–3203, 2004  相似文献   

5.
Conductivity stability at thermal environment of conductive polyaniline‐complexes/polyimide (PANI‐complexes/PI) blends, which were doped by camphorsulfonic acid (CSA) and dodecylbenzenesulfonic acid (DBSA), respectively, were investigated by conductivity measurements, electron spin resonance (ESR) spectra, differential and scanning thermometer (DSC). In the conversion process of PANI/Polyamic acid (PAA) to PANI/PI, the blend endeavored some kinds of alteration such as decomplexation of moisture and solvent, dissociation of dopant, crosslinking of PANI chain, and the imidization of PAA chain. PANI‐DBSA/PI showed higher thermal stability of conductivity than PANI‐CSA/PI, and both samples showed nearly linear decay of conductivity with increasing temperature showing greatly enhancement of conductivity stability. When they were exposed at near or over glass transition temperature, the conductivity decay became faster. The conductivity stability at base environment was also higher for PANI‐DBSA/PI due to difficulty in accessing of hydroxyl ion to PANI, which were resulted from dopant. DBSA‐doped blends showed increased polaron mobility and concentration at relatively high temperature, which led to extremely higher conductivity and its stability at high temperature. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

6.
The compatibilization effect of linear low‐density polyethylene‐grafted maleic anhydride (LLDPEgMA) and high‐density polyethylene‐grafted maleic anhydride (HDPEgMA) on high‐density polyethylene (HDPE)/polyamide 6 (Nylon 6) blend system is investigated. The morphology of 45 wt %/55 wt % polyethylene/Nylon 6 blends with three compatibilizer compositions (5 wt %, 10 wt %, and 15 wt %) are characterized by atomic force microscopic (AFM) phase imaging. The blend with 5 wt % LLDPEgMA demonstrates a Nylon 6 continuous, HDPE dispersed morphology. Increased amount of LLDPEgMA leads to sharp transition in morphology to HDPE continuous, Nylon 6 dispersed morphology. Whereas, increasing HDPEgMA concentration in the same blends results in gradual morphology transition from Nylon 6 continuous to co‐continuous morphology. The mechanical properties, oxygen permeability, and water vapor permeability are measured on the blends which confirm the morphology and indicate that HDPEgMA is a better compatibilizer than LLDPEgMA for the HDPE/Nylon 6 blend system. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 281–290  相似文献   

7.
Small-angle neutron scattering (SANS) and light scattering studies were carried out on an organogel consisting of a gelator, coded P-1, and dimethyl sulfoxide (DMSO). The gelator was made of an oligosiloxane stem and about eight branches of an amino acid derivative combined with a long alkyl chain. The amino acid part, N-n-pentanoyl-L -isoleucylaminooctadecane, was responsible for intermolecular association via hydrogen bonding between amide groups. After the complete dissolution of P-1 in DMSO at 85 °C, the solution was cooled, and the variations of the scattered light intensity were monitored as a function of the temperature. The scattered intensity increased drastically at about 40 °C when the P-1 concentration (C) was 3.5 g/L, and this indicated gel formation. The SANS results showed that the scattering intensity function was a monotonically decreasing function, regardless of C. A master relationship of the scattering intensity was obtained with respect to C. These scattering studies disclosed the following facts. First, gelation could be monitored as an abrupt increase in the intensity. Second, the gel was composed of randomly oriented bundlelike clusters. Third, the structure factor could be reduced by the gelator concentration, and this indicated the presence of a self-similar structure across the gelation threshold. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1841–1848, 2004  相似文献   

8.
Although polyaniline (PANI) has high conductivity and relatively good environmental and thermal stability and is easily synthesized, the intractability of this intrinsically conducting polymer with a melting procedure prevents extensive applications. This work was designed to process PANI with a melting blend method with current thermoplastic polymers. PANI in an emeraldine base form was plasticized and doped with dodecylbenzene sulfonic acid (DBSA) to prepare a conductive complex (PANI–DBSA). PANI–DBSA, low‐density polyethylene (LDPE), and an ethylene/vinyl acetate copolymer (EVA) were blended in a twin‐rotor mixer. The blending procedure was monitored, including the changes in the temperature, torque moment, and work. As expected, the conductivity of ternary PANI–DBSA/LDPE/EVA was higher by one order of magnitude than that of binary PANI–DBSA/LDPE, and this was attributed to the PANI–DBSA phase being preferentially located in the EVA phase. An investigation of the morphology of the polymer blends with high‐resolution optical microscopy indicated that PANI–DBSA formed a conducting network at a high concentration of PANI–DBSA. The thermal and crystalline properties of the polymer blends were measured with differential scanning calorimetry. The mechanical properties were also measured. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3750–3758, 2004  相似文献   

9.
Conducting polymer blends whose undiluted components have different properties are promising materials for specific applications and have attracted interest in recent years. The aim of this study was to obtain and evaluate the electrical conductivity of polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA)/polyurethane thermoplastic (TPU) blends. The PAni.DBSA was synthesized from DBSA-aniline (DBSAn) salt through an emulsion polymerization in tetrahydrofurane (THF) or in the presence of polyurethane thermoplastic solution, resulting in pure PAni.DBSA or PAni.DBSA/TPU blends. Blends of PAni.DBSA/TPU were also prepared through casting, at room temperature, after dissolving both components in THF as a common solvent. The insulator-conductor transition was very sharp and the percolation threshold was lower than 2.7 wt% of PAni.DBSA. The electrical conductivity of PAni.DBSA/TPU blends, prepared by both methods, reached maximum values at a PAni.DBSA concentration of 40 wt%, close to the value observed for the undiluted conducting polymer. However, for a PAni.DBSA content lower than 30 wt%, the electrical conductivity was dependent on the blend preparation method. Blends were characterized by infrared spectroscopy, thermogravimetric analysis (TG) and optical microscopy. The electrical conducting characteristics of the PAni.DBSA/TPU blends prepared using different procedures indicate a high potential for their successful application in electrical processes.  相似文献   

10.
The influence of shear on viscoelastic solutions of poly(ethylene oxide) (PEO) and clay [montmorillonite, i.e., Cloisite NA+ (CNA)] was investigated with rheology and small-angle neutron scattering (SANS). The steady-state viscosity and SANS were used to measure the shear-induced orientation and relaxation of the polymer and clay platelets. Anisotropic scattering patterns developed at much lower shear rates than in pure clay solutions. The scattering anisotropy saturated at low shear rates, and the CNA clay platelets aligned with the flow, with the surface normal parallel to the gradient direction. The cessation of shear led to partial and slow randomization of the CNA platelets, whereas extremely fast relaxation was observed for laponite (LRD) platelets. These PEO–CNA networklike solutions were compared with previously reported PEO–LRD networks, and the differences and similarities, with respect to the shear orientation, relaxation, and polymer–clay interactions, were examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3102–3112, 2004  相似文献   

11.
It has been suggested that, due to topological constraints, rings in the melt may assume a more compact shape than Gaussian chains. In this paper, we exploit the availability of narrow fractions of perdeuterated linear and cyclic polydimethylsiloxane (PDMS) and, through the analysis of the small angle neutron scattering (SANS) profiles, demonstrate the difference in scattering properties of linear and cyclic PDMS molecules. As expected for Gaussian chains, for the H/D linear PDMS samples, log-log plots of the scattered intensity versus scattering vector Q display a Q((-2)) dependence. However, for H/D cyclic blends, the scaling exponent is higher than 2, as predicted by computer simulations reported in the literature. We show that cyclic molecules in bulk display the characteristic maximum in plots of scattered intensity versus Q((-2)) that is expected on the basis of Monte Carlo calculations and from the Casassa equation [E. F. Casassa, J. Polym. Sci. A 3, 605 (1965)]. It is also shown that, for rings, the Debye equation [P. Debye, J. Appl. Phys. 15, 338 (1944)] is no longer appropriate to describe the SANS profiles of H/D cyclic blends, at least up to M(w) approximately 10 000. For these samples, the Casassa form factor gives a better representation of the SANS data and we show that this function which was developed for monodisperse cyclics is still adequate to describe our slightly polydisperse samples. Deviations from all above observations are noted for M(w)>11 000 and are attributed to partial contamination of cyclic samples with linear chains. The failure of both the Debye and the Casassa form factors could be due to contamination of the cyclic fractions by linear polymers or to a real conformational change.  相似文献   

12.
The aim of this study was to determine the interaction parameter xAB and its variation with temperature from the intensity scattered By pure block copolymer (A-B) and block copolymer-homopolymer (B) blends where A is polydeuteratedstyrene and B polybutadiene. SANS experiments on pure copolymers of low molecular weight have shown that the scattering curve exhibits a peak of intensity related to the correlation hole effect. χAB was determined by fitting the experimental curves using Leibler's theory and the law of variation of χAB versus temperature was established. In the case of copolymer-homopolymer blends, the scattering spectrum is modified because of a new and additional long range correlation effect (mixing effect) which dominates in the low q range and leads to strong forward scattering. We have not found any significant variation of χ with blend composition.  相似文献   

13.
The solid‐state three‐dimensional ordering of polyaniline–dopant complexes was investigated with four structurally different sulfonic acid dopants. The doped materials were produced in three different ways: polyaniline emeraldine base doped with sulfonic acid (aqueous route), in situ polymerization at the organic–water solvent interface (interfacial route), and in situ polymerization in organic and aqueous solvent mixtures (bilayer route). p‐Toluenesulfonic acid (PTSA), 5‐sulfosalicilic acid (SSA), camphorsulfonic acid (CSA), and dodecylbenzene sulfonic acid (DBSA) were employed as dopants. The conductivity of the aqueous‐route samples showed 10 and 100 times higher conductivity than the interfacial and bilayer routes, respectively. WXRD studies suggested that the crystallinity of the doped samples was dependent on both the structure of the dopants and the polymerization techniques. DBSA increases the polyaniline interplanar distance and produced highly crystalline materials via the aqueous and bilayer routes but failed with the interfacial route because of poor solubility in water. CSA, PTSA, and SSA produced highly crystalline samples by the interfacial route but failed with the aqueous (except for CSA) and bilayer routes. SEM analysis revealed that the doped materials of the interfacial route had excellent continuous morphology and uniform submicrometer‐size particle distributions in comparison with those of the aqueous and bilayer routes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1321–1331, 2005  相似文献   

14.
Small‐angle neutron scattering (SANS) was used to examine the melt phase behavior of a heavily branched comb PEE polymer blended separately with two linear PEE copolymers. In this case, PEE refers to poly(ethylene‐r‐ethylethylene) with 10% ethylene units; therefore, the molecular architecture was the only difference between the two components of the blends. The molecular weights of the two linear random copolymers were 60 and 220 kg/mol, respectively. The comb polymer contained an average of 54 long branches, with a molecular weight of 13.7 kg/mol, attached to a backbone with a molecular weight of 10 kg/mol. Three different volume compositions (25/75, 50/50, and 75/25) were investigated for both types of blends. SANS results indicate that all the blends containing the lower molecular weight linear polymer formed single‐phase mixtures, whereas all the blends containing the high molecular weight linear polymer phase‐separated. These results are discussed in the context of current theories for polymer blend miscibility. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2965–2975, 2000  相似文献   

15.
We examine the crystallization and chain conformation behavior of semicrystalline poly(ethylene oxide) (PEO) and amorphous poly(vinyl acetate) (PVAc) mixtures with wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and small‐angle neutron scattering (SANS) experiments. For blends with PEO weight fractions (wtPEO) greater than or equal to 0.3, below the melting point of PEO, the WAXD patterns reveal that crystalline PEO belongs to the monoclinic system. The unit‐cell parameters are independent of wtPEO. However, the bulk crystallinity determined from WAXD decreases as wtPEO decreases. The scattered intensities from SAXS experiments show that the systems form an ordered crystalline/amorphous lamellar structure. In a combination of WAXD and SAXS analysis, the related morphological parameters are assigned correctly. With the addition of amorphous PVAc, both the average amorphous layer thickness and long spacing increase, whereas the average crystalline layer thickness decreases. We find that a two‐phase analysis of the correlation function from SAXS, in which the scattering invariant is linearly proportional to the volume fraction of lamellar stacks, describes quantitatively the crystallization behavior of PEO in the presence of PVAc. When wtPEO is close to 1, the samples are fully spaced‐filled with lamellar stacks. As wtPEO decreases from 1.0 to 0.3, more PVAc chains are excluded from the interlamellar region into the interfibrillar region. The fraction outside the lamellar stacks, which is completely occupied with PVAc chains, increases from 0 to 58%. Because the radius of gyration of PVAc with a random‐coil configuration determined from SANS is smaller than the average amorphous layer thickness from SAXS, we believe that the amorphous PVAc chains still persist with a random‐coil configuration even when the blends form an ordered structure. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2705–2715, 2001  相似文献   

16.
Studies of immiscible blend compatibilization often involve laborious microscopy methods to characterize changes in the particle size distribution with time in the melt. Here we explore a simple alternative approach based on Porod scattering from the two-phase structure. Although micron-sized particles in immiscible polymer blends are too large to be fully characterized by small-angle scattering, Porod scattering measurements of the interfacial area combined with knowledge of the blend volume fraction allows determination of an average particle diameter from a single scattering measurement. This technique is illustrated in experiments monitoring coarsening of particle size in polystyrene/poly(methyl methacrylate) blends prepared either by melt blending or solid-state shear pulverization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3413–3420, 2005  相似文献   

17.
The phase behavior of [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) blends with amorphous polymers with different degrees of aromaticity has been investigated by differential scanning calorimetry (DSC) and small‐angle neutron scattering (SANS). The polymers investigated are the homologous series of polystyrene (PS), poly(2‐vinyl‐naphthalene) (P2VN), and poly(9‐vinyl‐phenanthrene) (P9VPh). The DSC results show that the miscibility of PCBM in these polymers increases nonlinearly from 16.5 wt % in PS, 57.0 wt % in P2VN, and 74.9 wt % in P9VPh. The SANS results show that at all concentrations of PCBM, the blends are composed of two mixed phases. Analysis shows that the phase dimensions remain largely independent of PCBM content, but there is a strong dependence of the PCBM concentration difference in the two phases with increasing PCBM content. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 994–1001  相似文献   

18.
Small angle neutron scattering (SANS) is used to measure the size and the dispersion of synthetic polymers in matrix-assisted laser desorption/ionization (MALDI) matrixes. Deuterated polystyrene (DPS) and dithranol in tetrahydrofuran were deposited by electrospray onto a substrate for small angle neutron scattering (SANS) measurements. DPS with 6050 and 27,000 g mol(-1) molecular masses were prepared at mass fractions between 0.2 and 6%. All samples contained large aggregates of DPS with characteristic sizes >200 A that represent hundreds of aggregated chains. Samples of mass fraction 1% DPS (6050 g mol(-1)) in 2,5-dihydroxybenzoic acid, all-trans-retinoic acid, and sinapinic acid also have large zero angle scattering characteristic of large aggregates. The morphological trend obtained from the SANS measurements of the DPS aggregate size in the four matrixes is dithranol > 2,5-dihydroxybenzoic acid > all-trans-retinoic acid > sinapinic acid. These measurements indicate that DPS in dithranol exhibits the most strong phase separation, while DPS in sinapinic acid shows considerable domain mixing. All of these matrixes produce MALDI signal strength under appropriate conditions, suggesting that strong phase separation does not diminish the signal-to-noise ratio. DPS (188,000 g mol(-1)) in biphenyl was used as a model system of a matrix that can be either crystalline or amorphous. SANS data shows that above the biphenyl melting point, a conventional solution is formed that has molecularly dispersed polymers. Upon crystallization, there is strong aggregation of the DPS into large domains. Therefore, the crystalline matrixes commonly used in MALDI measurements probably cause large aggregations of polymers to be present during the MALDI process.  相似文献   

19.
Deuterium-labeled polystyrene modified by random distributions of the comonomer p-(1,1,1,3,3,3-hexaflouro-2-hydroxyisopropyl)-α-methyl-styrene [DPS(OH)] has been blended with poly(butyl methacrylate) (PBMA) and studied with small-angle neutron scattering (SANS). Miscibility is induced via hydrogen bonding between the DPS(OH) hydroxyl group and PBMA carbonyl groups. The data suggest that the nature of the miscible-phase structure in these blends differs from that of the usual homopolymer blends at small scattering angles, which we attribute to the short-range site specific nature of the hydrogen bond interaction. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2745–2750, 1998  相似文献   

20.
Following a previous investigation on partitioning of some macrocycle compounds in sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) aqueous solutions and their effect on the micellar structure, a small-angle neutron scattering (SANS) study has been performed at fixed surfactant content (0.20 mol/L) and varying macrocycle concentrations from 0.20 up to 1.0 mol/L. Conductivity measurements have been also performed in order to evaluate the effect of the presence of macrocycles on the critical micellar concentration (cmc) of the two surfactants. SANS experimental data were fitted successfully by means of a core-plus-shell monodisperse prolate ellipsoid model. It has been found that 1,4,7,10,13,16-esaoxacyclooctadecane (18C6) and 4,7,13,16-tetraoxa-1,10-diazacyclooctadecane (22) do not interact with DTAB micelles whereas their sodium complexes interact with SDS aggregates and partially localize, as a consequence of electrostatic interaction, on the micellar surface or in the Stern layer. 2,5,8,11,14,17-Hexaoxabicyclo[16.4.0] dicosane (B18C6), as a consequence of the increased hydrophobic character with respect to 18C6, interacts with DTAB hydrocarbon chains and partially localizes in the inner part of micelles. This finding has been successfully used to justify the higher amount of B18C6 compared to the 18C6 one found in the SDS micellar phase. The substituted crown ether has been found localized both on the micelle surface via complex formation and in the inner part of micelles as a consequence of the increased hydrophobic character. For all systems, the aggregate size primarily decreases with the amount of macrocycle in the micellar phase. The interpretation of cmc trends as a function ofmacrocycle concentration gives information on its distribution between micellar and aqueous phases that is in line with SANS results.  相似文献   

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