Preparation and characterization of cardanol‐based epoxy resin for coating at room temperature curing

Novel organic solvent‐free bio‐based epoxy resin for coating was prepared from cashew nut shell liquid which is one of renewable resources. The epoxy coating was fabricated by the reaction between amine compounds and epoxy cardanol prepolymer (ECP). The drying, physical, and thermal properties of the epoxy were investigated and compared with those of the commercial cashew coating. The ECP was synthesized by thermal polymerization under the various conditions. Based on the FT‐IR analysis, hydroxyl and carbonyl groups were generated, and viscosity increased with increasing heating temperature and time. On the other hand, the NMR analysis showed decrease in the degree of unsaturation in the side group of cardanol. Based on these results, the polymerization of the ECP could be autoxidized in the unsaturated group in the side chains. The drying time until harden dry of the ECP coating took about 2.5 h at room temperature, which is faster than that of the commercial cashew coating. This is because that the curing of ECP coating was based on the prepolymer (i.e., high molecular weight) and crosslink reaction between epoxy and amine groups. The ECP coating was rubbery state due to the flexible side chains of cardanol. Furthermore, the ECP coating improved chemical stability compared with the commercial cashew. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2468–2478, 2013     

Optical and conductivity studies of Pseudo‐doped chitin‐polyaniline blend

In this article, we report the preparation and characterization of self‐doped conducting chitin, polyaniline blends by solution blending method. The characterization of the blends was done by UV–vis absorption spectrum, FTIR, and conductivity studies. Conductivity of the self doped blends increases from less than ～10^?7 S/cm to 2.15 × 10^?5 S/cm, depending on the percentage of polyaniline in the blend. Spectroscopic analysis shows interaction between chitin and polyaniline and the electronic states are similar to those of the emeraldine and protonically doped forms of polyaniline. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of annealing on electrical conductivity and morphology of polyaniline films

We report structure–property relationships of polyaniline emeraldine base (EB) films that were produced by combining different processing steps in various sequences. The effect of annealing and doping processes on the surface structure of the films was investigated by atomic force microscopy (AFM), and the corresponding changes to the chemical structure of the EB films were monitored by Fourier transform infrared spectroscopy. AFM results indicate that after doping polyaniline (EB) films with HCl, the root mean square (rms) roughness of the surface of EB film increased ～ 46%. When the doped films were annealed at 180°C under a nitrogen atmosphere for 3 h, the rms roughness was essentially unchanged from that of the initial, undoped films. The electrical conductivity of the films also showed a significant dependence on the processing sequence. When the doped polyaniline (EB) films were annealed, no electrical conductivity was observed. When these films were redoped, only ～ 6% of the initial conductivity could be recovered. In another processing sequence in which the polyaniline (EB) films were first annealed and then doped, the electrical conductivity was only ～ 12% relative to the film that was doped immediately after being cast. From this work, a strategy to reduce the surface roughness of films made from electrically conducting polyaniline (EB) is proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3602–3610, 2001     

Effect of conductive polyaniline in thermoplastic natural rubber blends on the mechanical,thermal stability,and electrical conductivity properties

This research was conducted to fabricate thermoplastic natural rubber/polyaniline (TPNR/PANI) blends via melt blending method using an internal mixer and followed by compression molding. The effects of PANI contents between 1 and 5 wt % PANI in the TPNR blends on the mechanical properties, thermal stability, electrical conductivity (impedance), and morphology observation were investigated. The TPNR/3 wt % PANI sample exhibited the highest tensile strength (3.7 MPa), elongation at break (583%), flexural strength (1.8 MPa), flexural modulus (37.0 MPa), and impact strength (7.1 kJ m⁻²). From the aspect of thermal properties, it was found that with the addition of PANI, the thermal stability of the TPNR/PANI increased. Comparing to nonconductive TPNR sample, the incorporation of PANI promoted the electrical conductivity characteristic to PANI-filled TPNR blends which showing a magnitude order of 10⁻⁹ S cm⁻¹. Scanning electron microscopy micrograph revealed the good distribution of PANI at the optimum content (3 wt % PANI) in the TPNR blends and the good interaction between TPNR and PANI. It can be concluded that the TPNR blends incorporated with a low loading of PANI could be a newly good conductive material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47527.     

Effect of glycerol on electrical conducting of chitosan/polyaniline blends

Chitosan (Cs) and polyaniline (PANI) were studied in this article for possible application as conductive and flexible films. Cs is a biodegradable polymer, that presents interesting properties as film applications. Otherwise, PANI is a semiconductor polymer with a wide range of applications. The films were produced by casting adding 30% glycerol and glutaraldehyde. The morphology, thermally, chemical structure, and electrical properties of films were obtained. Results showed the casting technique becomes possible to obtain self-standing films, with a chemical structure identical to precursor materials. Glutaraldehyde reacted to amine groups of terminal PANI chains, acting in the increase of electric conductivity and decrease of sheet resistance. The plasticizing effect of glycerol increased the spacing between Cs chains and facilitated the PANI dispersion. Therefore, glycerol and glutaraldehyde proved to be extremely efficient in increasing the electrical conductivity of blends.     

Elaboration of superparamagnetic cobalt–ferrite nanocomposites from films of chitosan chelates

Cobalt–ferrite nanocomposites were synthesized from polymeric films of chelates of Co(II) and Fe(III) ions within a chitosan matrix by a solid‐state coprecipitation reaction with weight content ratios of chitosan to cobalt–ferrite of 50/50 and 25/75 w/w. Morphological and crystalline studies of the composites were performed by high‐resolution transmission electron microscopy, X‐ray diffraction, and selected area electron diffraction with a nanobeam diffraction probe. The results show nanoparticles around 4 nm with a spinel structure, consistent with the cobalt–ferrite phase. The magnetic behavior was evaluated with curves of the applied‐field‐dependent magnetization [M(H)] and the temperature‐dependent magnetization [M(T)]. Both the M(H) and M(T) curves showed typical superparamagnetic behavior, depicting an absence of hysteretic characteristics and the characteristic peak at blocking temperature in the zero‐field‐cooled curve. There was also evidence of strong interparticle and intraparticle interactions, which suggested magnetic frustration in the particle magnetic moment alignment with the applied field. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of PLA crystallization on the structure of biomimetic composites of PLA and clay

Composites of poly(lactic acid) (PLA) and organoclays with clay loadings of up to 80% were prepared as self‐supporting films using a doctor‐blading approach. Depending on the properties of the used organoclay, either intercalated nanocomposites or conventional composites were obtained. The incorporation of such high amounts of clay resulted in up to 10‐fold decrease in the water vapor transmission rate when compared to the pristine polymer. The effect of clay platelets on the crystallization of PLA chains was also studied; it was found that high amounts of clay hinder only the melt crystallization of the polymer, whereas cold crystallization proceeds as usual. On the other hand, the crystallization of PLA also influenced the composite structure by increasing the extent of intercalation of polymer between clay layers. This study thus shows that the change in the extent of clay‐polymer interactions is also an important factor in controlling nanocomposite structure, especially for high loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Investigation on microstructural behavior of styroflex/polyaniline blends by WAXS

Styroflex/polyaniline (STF/PAni) blends were prepared by two routes namely by in situ and thermo mechanical processing method with various PAni compositions, namely, 0, 15, 30, and 45 wt %. The influence of volume fraction of PAni in the blends and synthetic routes of the STF/PAni blends on the volume resistivity and microcrystalline parameters have been investigated. The microcrystalline parameters such as the nanocrystal size (<N>), lattice disorder (g), interplanar distance (d_hkl), width of the crystallite size distribution, surface weighted crystal size (D_s), and crystallite area were evaluated from the wide angle X‐ray scattering profiles. The different asymmetric column length distribution functions namely, exponential, reinhold, and lognormal distribution methods were employed to probe the microcrystalline behavior of the STF/PAni blends and the results are compared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber

Blend films (free‐standing) containing 20% in volume of polyaniline (PANI) in 80% of natural rubber (NR) were fabricated by casting in three different ways: (1) adding PANI‐EB (emeraldine base) dissolved in N‐methyl‐2‐pyrrolidone (NMP) to the latex (NRL), (2) adding PANI‐EB dissolved in m‐cresol to NR dissolved in xylol (NRD), (3) overlaying the surface of a pure NR cast film with a PANI layer grown by in situ polymerization (NRO). All the films were immersed into HCl solution to achieve the primary doping (protonation) of PANI before the characterization. The main goal here was to investigate the elastomeric and electrical conductivity properties for each blend, which may be applied as pressure and deformation sensors in the future. The characterization was carried out by optical microscopy, dc conductivity, vibrational spectroscopy (infrared absorption and Raman scattering), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile stress–strain curves. The results suggest that the NRL blend is the most suitable in terms of mechanical and electrical properties required for applications in pressure and deformation sensors: a gain of conductivity without losing the elastomeric property of the rubber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1498–1503, 2005     

Effect of electron-withdrawing type substituents in the polyaniline ring on the electrical conductivity

Summary Poly(ethyl 3-aminophenyl formate), poly(ethyl 3-aminophenyl acetate) and poly(ethyl 3-aminophenyl propionate) were synthesized in 1 M HCl media from respective monomers using ammonium persulphate as oxidizing. The polymers were characterized by FT-IR, UV-vis and ¹H-NMR spectroscopy. The effect of electron-withdrawing on the electrical conductivity of polyaniline, was studied. The electron-withdrawing group (ester) bond to the aniline ring affects the formation of charge carriers and electrical conductivity of polymers, therefore, at various bond lengths of the aniline ring, the electron-withdrawing effect decreases and a polymer with electrical conductivity from the semi-conduction order is obtained.     

Preparation of cardanol–formaldehyde resins from cashew nut shell liquid for the reinforcement of natural rubber

Natural rubber was reinforced with a high loading of a cardanol–formaldehyde resin prepared from cashew nut shell liquid. Cardanol–formaldehyde resins, both resoles and novolaks, were synthesized from cardanol, which was extracted from cashew nut shells. This was done by the condensation polymerization of cardanol and formaldehyde in the presence of base and acid catalysts. The cardanol–formaldehyde resole with the highest yield (ca. 75%) was prepared with a formaldehyde/cardanol molar ratio of 2.0 at pH 8.0 and 90°C for 8 h. The cardanol–formaldehyde novolak with the highest yield (ca. 80%) was prepared with a formaldehyde/cardanol molar ratio of 0.8 at pH 2.2 and 100°C for 7 h. Fourier transform infrared and ¹³C‐NMR were employed to characterize the chemical structures of the obtained cardanol–formaldehyde resins. The resins were compatible with natural rubber in various formulations. The cured behaviors of natural rubber blended with the cardanol–formaldehyde resole and novolak resins were investigated. The cured behaviors of cardanol–formaldehyde resole and cardanol–formaldehyde novolak samples were different, reflecting differences in their chemical reactivities. Furthermore, the incorporation of cardanol–formaldehyde resins into natural rubber provided significant improvements in mechanical properties such as the hardness, tensile strength, modulus at 100 and 300% elongation, and abrasion resistance. However, the elongation at break and compression set of the blends decreased as expected. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1997–2002, 2007     

Synthesis and characterization of polyacrylamide–polyaniline conductive blends

Conducting poly(acrylamide) films were synthesized by exposing the polyacrylamide films impregnated with ammonium peroxodisulphate, an oxidizing agent, to hydrochloric acid vapor and then to aniline vapor. The effects of varying the exposure time to aniline vapor and the resulting composite films of polyacrylamide–polyaniline were characterized by different methods. The mode of conduction has also been studied. The conductivity of the resulting composites reached up to 10⁻⁵ s/cm². © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 841–844, 1998     

Characterization of polymer‐layered silicate (clay) nanocomposites by transmission electron microscopy and X‐ray diffraction: A comparative study

Several polymer‐layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide‐angle X‐ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene‐g‐maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d‐spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand‐alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003     

Effect of m‐nitroaniline doping on the optical humidity‐sensing characteristics of cobalt/poly(vinyl alcohol) nanocomposites

Cobalt (Co) nanoparticles (with different loadings, 1 and 2 wt %, of Co) were synthesized in situ in a poly(vinyl alcohol) (PVA) matrix with and without meta‐nitroaniline (m‐NA) as a dopant (2.5 wt %). The obtained nanocomposite films were characterized with various physicochemical techniques, including ultraviolet–visible spectrophotometry, X‐ray diffraction analysis, scanning electron microscopy, and Fourier transform infrared analysis. To study the effect of the humidity, the nanocomposite solutions were coated on planar glass substrates. The beam of an He–Ne laser was incident normal to the film surface and was subjected to variable relative humidities (RHs; 4–93%); the transmitted intensity was measured on a photovoltaic diode. Variations in the intensity of light caused by the changes in RH within the range 3–93% were recorded. We optimized the response by varying the film thickness by coating the solution layer by layer. We generated the RH (4–100%) by passing wet water vapors. The neat PVA film of similar thickness gave humidity sensing in the range 78–93% RH. The sensors with m‐NA‐doped Co/PVA gave better sensitivity (6.4 mV/% RH) than the undoped samples (1.78–2.45 mV/% RH), exhibiting a fast response of 3 s (2–93% RH) and a recovery of 10 s (93 to 2% RH). These samples also showed reversible behavior and long‐term stability (for nearly a year) with a good sensitivity and a large dynamic range (2–95% RH). An attempt was made to explain the results on the basis of a bulk mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of polyaniline and studying its electrical conductivity

Polyaniline was prepared by chemical methods. Its electrical conductivity was measured. The electrical conductivity of polyaniline salt and polyaniline base were compared with composites prepared by the hot press of polyaniline base with KBr, Co(CH₃COO)₂, and picric acid. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1658–1665, 2000     

Studies of AC conductivity and dielectric relaxation behavior of CdO‐doped nanometric polyaniline

The Cadmium oxide doped in nanocrystalline polyaniline (CdO/PANI) composite were prepared with various weight percentages by in situ polymerization method using aniline, ammonium per sulfate, and CdO as starting materials. The frequency dependent conductivity and dielectric behavior of PANI/CdO composites have been studied. The formation of nano PANI and PANI/CdO composites with regards to the structural and microstructural properties of the materials were investigated by XRD, FTIR, and SEM techniques. The variation of σ_ac with frequency obeys Jonscher power law except a small deviation in the low frequency region and is due to dipole polarization effect. The σ_ac increases with increase in CdO concentration. Studies of dielectric properties at lower frequencies show that the relaxation behavior is superimposed by dipole polarization effect. The appearance of peak for each concentration in the loss tangent suggests the presence of relaxing dipoles in the PANI/CdO composite. On addition of CdO, the peak shifts toward higher frequency side indicating the speed up of the relaxation time. Analysis of frequency dependent dielectric suggests that the electronic and polymer segmental motions are strongly coupled. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

溶胀处理煤对煤结构与煤基聚苯胺导电性影响

首次选用苯胺为溶剂对神府煤(SFC)进行溶胀处理,以研究其对煤结构与煤基聚苯胺导电性的影响,对其结构进行TG/DSC、FTIR和SEM分析,并通过溶胀SFC处理煤为聚合基体,在苯胺和引发剂条件下聚合为煤基聚苯胺,测定了其导电率。结果表明:苯胺溶胀处理破坏了煤中非共价键,降低了煤的交联缔合度,疏松了煤的孔结构,在此条件下的煤基聚苯胺的导电率均小于溶胀处理前原煤为聚合基体的煤基聚苯胺导电率,这与煤大分子网络结构受到一定程度破坏有关,这可为煤基聚苯胺的扩大化生产提供重要参考。     

Thermal behavior of polyaniline films and polyaniline–polystyrene blends

In this article, a study of the thermal behavior of polyaniline films and polyaniline–polystyrene blends is presented. Transport measurements (electrical conductivity and thermoelectric power) at high temperature and thermogravimetric analysis show that an irreversible degradation is observed near 450 K for films doped with DiOHP and near 500 K for films doped with CSA. In both cases, the thermoelectric power is the most sensitive parameter to electrical degradation during the heating of conducting films. Electrical conductivity measurements during heating–cooling cycles show a diminution of the room temperature conductivity after evaporation of the solvent (water, m‐cresol). A model of cluster with a variable diameter allows interpreting this phenomenon by assuming the existence of a sensitive frontier to the solvent at the periphery of conducting clusters. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1848–1855, 2002; DOI 10.1002/app.10468     

Effect of organoclay structure and mixing protocol on the toughening of amorphous polyamide/elastomer blends

An amorphous polyamide (a-PA) was blended with an ethylene-1-octene (EOR) elastomer with organoclays present to control the elastomer particle size. Four different organoclays, M₃(HT)₁, M₂(HT)₂, M₁H₁(HT)₂, and (HE)₂M₁T₁ and two different mixing protocols were used to investigate the effect of the organoclay structure and mixing protocol on the morphology and properties of the resulting blends. Wide angle X-ray scattering, transmission electron microscopy, and stress-strain behavior were used to evaluate the degree of exfoliation of the organoclays and the morphology of the elastomer particles for these blends. A detailed particle analysis was made to provide a quantitative assessment of elastomer particle size. The size and shape of the elastomer particles were dramatically affected by the amount of organoclay but the organoclay type and the mixing protocol led to slight differences. Broadly speaking, most of the MMT platelets are well exfoliated in the a-PA phase, but some locate at the interface and tend to envelop the EOR phase. The mechanical properties were not significantly affected by the organoclay type or the mixing protocol. While the organoclays reduced the EOR particles to size range where toughness might be expected, all blends proved to be brittle. A clear trade-off was observed between the Izod impact strength and tensile modulus for these blends containing organoclays.     

Wheat gluten nanocomposite films as food‐contact materials: Migration tests and impact of a novel food stabilization technology (high pressure)

The aptitude of a novel biodegradable material [wheat gluten/montmorillonite (MMT)] to be used as a food‐contact material was assessed with a focus on mass transfer from the film into foodstuff (migration). Special attention was paid to the impact of high‐pressure treatments and subsequent storage. Several aspects were treated: the migration of a model molecule (Uvitex OB), MMT migration, protein migration, and overall migration. The results showed that overall migration and protein migration were high; on the contrary, MMT and Uvitex OB migration was low or not detectable. No difference was found between the high‐pressure‐treated samples and the control, except for the migration of MMT. Two solid simulants (agar gel and Tenax) were also tested to emphasize the need of new migration tests adapted to water‐sensitive materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010