Mechanical properties study of micro‐ and nano‐hydroxyapatite reinforced ultrahigh molecular weight polyethylene composites

This is a comparative study between ultrahigh molecular weight polyethylene (UHMWPE) reinforced with micro‐ and nano‐hydroxyapatite (HA) under different filler content. The micro‐ and nano‐HA/UHMWPE composites were prepared by hot‐pressing method, and then compression strength, ball indentation hardness, creep resistance, friction, and wear properties were investigated. To explore mechanisms of these properties, differential scanning calorimetry, infrared spectrum, wettability, and scanning electron microscopy with energy dispersive spectrometry analysis were carried out on the samples. The results demonstrated that UHMWPE reinforced with micro‐ and nano‐HA would improve the ball indentation hardness, compression strength, creep resistance, wettability, and wear behavior. The mechanical properties for both micro‐ and nano‐HA/UHMWPE composites were comparable with pure UHMWPE. The mechanical properties of nano‐HA/UHMWPE composites are better compared with micro‐HA/UHMWPE composites and pure UHMWPE. The optimum filler quantity of micro‐ and nano‐HA/UHMWPE composites is found to be at 15 wt % and 10 wt %, separately. The micro‐ and nano‐HA/UHMWPE composites exhibit a low friction coefficient and good wear resistance at this content. The worn surface of HA/UHMWPE composites shows the wear mechanisms changed from furrow and scratch to surface rupture and delamination when the weight percent of micro‐ and nano‐HA exceed 15 wt % and 10 wt %. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42869.     

Mechanical and thermal properties of biphenyldiol formaldehyde resin/gallic acid epoxy composites enhanced by graphene oxide

In this study, the gallic acid‐based epoxy resin (GA‐ER) and alkali‐catalysed biphenyl‐4,4′‐diol formaldehyde resin (BPFR) are synthesized. Glass fibre‐reinforced GA‐ER/BPFR composites are prepared. Graphene oxide (GO) is used to improve the mechanical and thermal properties of GA‐ER/BPFR composites. Dynamic mechanical properties and thermal, mechanical, and electrical properties of the composites with different GO content are characterized. The results demonstrate that GO can enhance the mechanical and thermal properties of the composites. The glass transition temperature, T_g, of the BPFR/GA‐ER/GO composites is 20.7°C higher than the pure resin system, and the 5% weight loss temperature, T_d5, is enhanced approximately 56.6°C. When the BPFR: GA‐ER mass ratio is at 4 : 6 and GO content is 1.0–1.2 wt %, the tensile and impact strengths of composites are 60.97 MPa and 32.08 kJ/m² higher than the pure resin composites, respectively. BPFR/GA‐ER composites have better mechanical properties, and can replace common BPA epoxy resins in the fabrication of composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42637.     

Ultrasonic properties of epoxy resin/marble waste powder composites

Non‐destructive techniques are suitable alternatives for characterization of composites. The aim of this study is to analyze the composites of epoxy resin (ER)/marble waste powder (MWP) by ultrasonic method. The effects of marble powder, coagulant type, and dosage on the ultrasonic properties of ER/MWP composites were investigated. The ultrasonic wave velocities of composites were measured with the pulse–echo method at room temperature by a flaw detector. The values of the acoustic impedance, Poisson's ratio, and elastic constants of the samples were calculated by the measured values of the densities and both longitudinal and shear ultrasonic wave velocities. According to the results, the ER/MWP composite using sepiolite coagulant in dosages of 4 g/500 mL has showed the highest values of elastic constants. POLYM. COMPOS. 36:584–590, 2015. © 2014 Society of Plastics Engineers     

Determination of elastic constants of epoxy resin/biochar composites by ultrasonic pulse echo overlap method

This study is carried out in order to determine the elastic properties of Epoxy Resin (ER) Composites reinforced with various mixtures of China Poplar Char (CPC) and Pine Cone Char (PCC) as biochars by ultrasonic wave velocity measurement method. The prepared chars are mixed with epoxy resin matrix at weight percentages of 10%, 20%, and 30% for preparing the ER/Biochars (BC) composites. The effect of biochar amounts on the elastic properties of the ER/BC composites are investigated by ultrasonic pulse echo overlap method. The morphologies of the samples are investigated by scanning electron microscopy. Based on the findings obtained from the present study, forming of the ER/CPC composites gives better values of elastic properties compared to forming of the ER/PCC composites. According to the obtained results, the composition ratio of 70:30 is the most appropriate composition ratio for both of the ER/CPC and the ER/PCC composites. POLYM. COMPOS., 37:2907–2915, 2016. © 2015 Society of Plastics Engineers     

Facile fabrication of polyaniline/polypyrrole copolymer nanofibers with a rough surface and their electrorheological activities

Hierarchical polyaniline/polypyrrole (PANI/PPy) copolymer nanofiber was prepared via a two‐step method and adopted as dispersing materials for electrorheological (ER) fluids. The first step was used to synthesize PANI nanofibers by a rapid mixing method. Subsequently, the PANI/PPy copolymer nanofibers with a rough surface were obtained using an in situ polymerization method continuously. The morphology of the resultant PANI/PPy copolymer nanofibers can be controlled by varying the amount of Py monomer in the secondary in situ polymerization method. The rough surface of PANI/PPy copolymer nanofibers were confirmed by scanning electron microscopy and transmission electron microscopy. The diameter of PANI/PPy nanofiber is within the range 100–200 nm. The obtained PANI/PPy copolymer particles all exhibit amorphous structure through X‐ray diffraction measurement. We also demonstrated that the hierarchical PANI/PPy copolymer nanofibers exhibited characteristic ER behaviors, which were investigated using a Haake rotational rheometer at various electric field strengths. The ER efficiency e for PANI‐1mLPPy and PANI‐2mLPPy ER fluids at shear rate 0.1 s⁻¹ is 36.6 and 28.5 under electric field strength E = 3 kV/mm, respectively. Low leaking current density is observed even at high electric field strength and wide plateau region appeared, which show a strong ER activity for the PANI/PPy composite nanofibers. The results also indicate that the PANI/PPy composite particles have distinctly enhanced ER effect compared with the pure PANI and PPy particles under electric stimuli. The significantly improved ER property of PANI/PPy‐based ER fluid is ascribed to the enhanced interfacial polarization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46289.     

Synthesis and characterization of crosslinked chitosan immobilized on bentonite and its grafted products with polyaniline

Chitosan immobilized bentonite (CIB) namely chitosan‐coated bentonite (5% chitosan content) was synthesized in 2% acetic acid solution, followed by crosslinking, using epichlorohydrien (ECH). The so‐obtained crosslinked chitosan immobilized on bentonite (CIB‐ECH) and CIB composites were grafted with polyaniline (PANI) through oxidative‐radical copolymerization using ammonium peroxydisulfate in acidic medium to produce PANI‐grafted crosslinked chitosan immobilized on bentonite (PANI‐g‐CIB‐ECH) and PANI‐grafted‐chitosan immobilized on bentonite (PANI‐g‐CIB) composites, respectively. The resultant composites were characterized by using X‐ray diffraction (XRD), thermo gravimetric analysis/differential scanning calorimetry, scanning electron microscopy, Fourier transform infrared (FTIR), and electrical conductivity. XRD and FTIR analyses indicate that chitosan was not intercalated into the silicate layer. Also the electrical conductivity elucidates that the grafted composites fall in the range required for the application as electrostatic dissipation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41078.     

Determining the mechanical properties of epoxy resin (DGEBA) composites by ultrasonic velocity measurement

In this study, the composites of diglycidyl ether of bisphenol A (DGEBA) epoxy resin that have been formed by mixing epoxy resin with allyl glycidyl ether (AGE) and 2,3‐epoxypropyl methacrylate [glycidyl methacrylate (GMA)] were prepared in weight % ratios of 90 : 10, 80 : 20, and 70 : 30. A computer controlled analyzer with 35 MHz and a digital oscilloscope with 60 MHz were used for measuring the velocities of ultrasonic wave. The measurement of ultrasonic velocity carried out by pulse echo method at frequencies of 2.25 and 3.5 MHz at room temperature. The values of acoustic impedance (Z), Poisson ratio (μ), and coefficients of elasticity (L, G, K, E) of composites were calculated by values of densities and velocities that obtained. Thus, the effect of modificating epoxy resin (DGEBA) by AGE and GMA on mechanical properties of DGEBA was investigated using the ultrasonic method. Atomic force microscopy has been used for determining the microstructure of composites. By the results obtained from the investigation, it have been established that the longitudinal and shear ultrasonic wave velocities, and the values of all the elasticity constants of DGEBA were increased by modification with AGE and GMA. Also the most suitable combination ratio for the compound of DGEBA : AGE and DGEBA : GMA has been found as 80 : 20. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.     

Fabrication of honeycomb‐patterned polyaniline composite films containing cellulose triacetate with high conductivity and mechanical stability

Polyaniline (PANI) biocomposites were prepared via in situ polymerization of aniline monomer with cellulose triacetate (CTA) and by using ammonium persulfate as an initiator in an aqueous solvent. The composites exhibited high solubility in organic solvents due to the incorporated CTA component, and enabled the fabrication of honeycomb‐patterned thin films by casting the PANI composite solutions under humid conditions. The honeycomb‐patterned PANI–CTA composite films showed a high conductivity corresponding to about 1.5 S/cm, good mechanical stability, and high flexibility. The composites have a potential advantage comparing to pure PANI because of biodegradability and high solubility due to included CTA. These composite films can usefully be applied in the field of bio‐nanotechnology and medicine including micro‐structured electrode surfaces, filters for cell sorting, and bio‐interfaces and so on. POLYM. COMPOS., 37:2649–2656, 2016. © 2015 Society of Plastics Engineers     

Optical,electrical, and electrochemical properties of graphene based water soluble polyaniline composites

Polyaniline (PANI) is one of the most common polymers known for its conducting properties. However, poor water solubility limits its applications. In this work, PANI has been functionalized with sulfonic acid groups to produce sulfonated PANI (SPANI) offering excellent solubility in water. To compensate for the decrease of electrical conductivity due to functionalization, SPANI was combined with reduced graphene oxide (RGO) to form SPANI/RGO composites with interesting optical, thermal, and electrical properties. The composites have been characterized using X‐ray diffraction (XRD), field emission scanning electron microscopy, UV–vis absorption spectroscopy, Raman spectroscopy, Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, cyclic voltammetry, and four probe electrical conductivity measurement. The SPANI/RGO composites show increased thermal stability, reduced optical band gap and improved electrochemical properties compared with the pure polymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42766.     

Preparation of epoxy composites with CTAB‐modified BN and MWCNTs

In this study, multi‐walled carbon nanotubes (MWCNTs) and boron nitride (BN) were functionalized with cetyltrimethylammonium bromide (CTAB) at both pH 5.5 and pH 11. These MWCNT‐CTAB and BN‐CTAB particles used to prepare the composites were dispersed in a bisphenol A (DGEBA)‐type epoxy resin (ER) system at room temperature. The TGA analysis showed that the BN composite can significantly improve the thermal stability of neat ER at temperatures above 400 °C. The curing degrees of the nanocomposites were calculated to be approximately the same values as neat ER using the Beer–Lambert law from FTIR spectra. The best electrical conductivity of the composites obtained was 3.10 × 10⁻³ S/cm for ER/MWCNT‐CTAB (pH 5.5). The surface hardness, Young's modulus, and tensile strength of the composites were examined. The surface hardness values of the ER/MWCNT‐CTAB composites were higher than those of the other composites. The composite morphology was characterized using X‐ray diffraction (XRD) and scanning electron microscopy (SEM). POLYM. COMPOS., 37:3423–3432, 2016. © 2015 Society of Plastics Engineers     

Properties of polyetherimide/graphite composites prepared using ultrasonic twin‐screw extrusion

The dispersion of various graphites in polymers is a challenging problem limiting their potential use. To solve this problem, an ultrasound assisted twin‐screw extruder was developed and utilized to compound polyetherimide (PEI) with untreated nature graphite (UG), modified graphite (MG) and expanded graphite (EG) at concentrations up to 10 wt %. The effect of ultrasonic amplitude on rheological, mechanical and electrical properties of the PEI composites was investigated. Ultrasonic treatment of PEI/UG composites showed little effect on these properties. In contrast, ultrasonic treatment of PEI/MG and PEI/EG composites led to an increase of the storage (G′), loss (G″) moduli and complex viscosity and to a decrease of the damping characteristics. In particular, the PEI/5 wt %EG composite ultrasonically treated at an amplitude of 10 μm showed a 45% higher complex viscosity than the untreated composite at a frequency of 0.5 rad/s. Also, the PEI/5 wt % EG composite treated at an amplitude of 10 μm showed a reduction in the electrical volume resistivity by almost three orders of magnitude leading to a lower percolation threshold. The untreated and treated PEI/UG and PEI/MG composites did not show any percolation within all graphite concentrations studied, due to large size of particles of UG and MG and their strong agglomeration. The ultrasonic treatment showed slight effect on mechanical properties of all these composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41397.     

Enhanced microwave absorbing properties of lightweight films based on polyaniline/aliphatic polyurethane composites in X band

Polymer blends based on nanostructured polyaniline (PANI) doped with hydrochloric acid (HCl) and para‐toluene sulfonic acid (PTSA) introduced into aliphatic polyurethane matrix (PU) are synthesized to produce flexible thin composite films for microwave absorbers. The effects of dopant type, PANI content and film thickness on morphologies, dielectric and microwave absorption properties in the X‐band are studied. It reveals that real and imaginary parts of the complex permittivity are proportional to filler concentrations and type of doped PANI. The PANI‐PTSA/PU films show higher permittivity and better microwave absorbing properties than PANI‐HCl/PU for the same weight fraction of PANI. The minimum reflection loss RL_(dB) values for the PANI‐PTSA/PU are ?37 dB at (20% PANI and 11.6 GHz) and ?30 dB at (15% PANI and 11.3 GHz) for thicknesses of 1.2 and 1.6 mm, respectively. These high values of reflection losses make the obtained lightweight and flexible composites promising radar absorbing materials (RAM). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40961.     

Preparation and properties of waterborne polyurethane/polyaniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid blends

A conductive poly(aniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid) [PANI‐D/H, yield: 32.2%, intrinsic viscosity ([η]): 1.39 dL/g, electrical conductivity: 7.3 S/cm] was synthesized by chemical oxidative polymerization from aniline‐dodecylbenzene sulfonic acid salt (A‐DS)/aniline‐hydrochloric acid salt (A‐HS) (6/4M ratio) in an aqueous system. Waterborne polyurethane (WBPU) dispersion obtained from isophorone diisocyanate/poly(tetramethylene oxide)glycol/dimethylol propionic acid/ethylene diamine/triethylene amine/water was used as a matrix polymer. The blend films of WBPU/PANI‐D/H with various weight ratios (99.9/0.1–25/75) were prepared by solution blending/casting. Effect of PANI‐D/H content on the mechanical property, dynamic mechanical property, hardness, electrical conductivity, and antistaticity of WBPU/PANI‐D/H blend films was investigated. The dynamic storage modulus and initial tensile modulus increased with increasing PANI‐D/H content up to 1 wt %, and then it was significantly decreased about the content. With increasing PANI‐D/H content, the glass transition temperature of soft segment (T_gs) and hard segment (T_gh) of WBPU/PANI‐D/H blend films were shifted a bit to lower the temperature. The tensile strength and hardness of WBPU/PANI‐D/H blend films increased a little with increasing PANI‐D/H content up to 0.5 wt %, and then it was dramatically decreased over the content. The elongation at break of WBPU/PANI‐D/H decreased with an increase in PANI‐D/H content. From these results, it was concluded that 0.5–1 wt % of PANI‐D/H was the critical concentration to reinforce those various properties of WBPU/PANI‐D/H blend films prepared in this study. The electrical conductivity of WBPU/ultrasonic treated PANI‐D/H (particle size: 0.7 μm) blend films prepared here increased from 4.0 × 10^?7 to 0.33 S/cm with increasing PANI‐D/H content from 0.1 to 75 wt %. The antistatic half‐life time (τ_1/2) of pure WBPU film was about 110 s. However, those of WBPU/ultrasonic treated PANI‐D/H blend films (τ_1/2: 8.2–0.1 s, and almost 0 s) were found to decrease exponentially with increasing PANI‐D/H content (0.1–9 wt %, and above 9 wt %). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 700–710, 2004     

The influence of PVP on the synthesis and electromagnetic properties of PANI/PVP/CIP composites

Polyaniline/carbonyl iron powder (PANI/CIP) composites with core‐shell structure were synthesized via in situ polymerization in aqueous solution of polyvinylpyrrolidon (PVP). The micromorphology, structure, and microwave absorbing property of the PANI/PVP/CIP composites were characterized by scanning electron microscopy, fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and vector network analysis. And, the modified mechanism of PVP on polymerization was discussed. The research showed that the presence of PVP was conducive to not only dispersion of CIP but also the formation coated well with PANI. PANI/CIP composites that were decorated by PVP have obviously improved on wave absorbing property compared with the composites which were synthesized without PVP. With the concentrations of 10 wt% PVP, the PANI/PVP/CIP composites show best microwave absorption, which the minimum reflection loss (RL) was −26.4 dB at 38.1 GHz and the corresponding thickness was 0.9 mm; for a thickness of 1.1 mm, an RL exceeding −10 dB was obtained in the frequency range of 27.6–39.0 GHz. POLYM. COMPOS., 36:1799–1806, 2015. © 2014 Society of Plastics Engineers     

Micro‐contact reconstruction of adjacent carbon nanotubes in polymer matrix through annealing‐Induced relaxation of interfacial residual stress and strain

Thermoplastic polyurethane (TPU)/multi‐walled carbon nanotubes (CNT) nanocomposites were prepared by twin‐screw extrusion and micro injection molding. The electrical conductivity of micro injection molded polymer nanocomposites exhibits a low value and uneven distribution in the micromolded samples. Real‐time tracing of electrical conductivity was conducted to investigate the post thermal treatment on the electrical conductivity of microinjection molded composites. The results show that postmolding thermal treatment leads to a significant increase in the electrical conductivity by over three orders of magnitude for 5 wt % CNT‐filled TPU composites. In‐situ Transmission electron microscopy confirms the conductive CNT network does not change at the micron/sub‐micron scale during thermal treatment. TEM image analysis by a statistical method was used to determine the spatial distribution of CNT in the sample and showed that the average distance between adjacent CNT reduced slightly at the nanometer scale after postmolding thermal treatment. A new conductive mechanism is proposed to explain the enhancement of electrical conductivity after thermal treatment, i.e. micro‐contact reconstruction of adjacent CNT in the polymer matrix through annealing‐induced relaxation of interfacial residual stress and strain. Raman spectra and small angle X‐ray scattering curve of annealed samples provide supporting evidence for the proposed new conductive mechanism. The electron tunneling model was used to understand the effect of inter‐particle distance on the conductivity of polymer composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42416.     

Manufacturing and mechanical characterization of perforated hybrid composites based on flexible polyurethane foam

This study focused on the fabrication and mechanical evaluation of nonwoven reinforced flexible polyurethane foam composites. Effects of perforation ratio, aperture size, and perforation depth on bursting and low‐velocity impact responses of perforated composite panels were investigated. The nonwoven fabric used for cover sheet was composed of flame retardant polyester, low‐melting point polyester, and recycled Kevlar staple fibers. Blending ratio of Kevlar fiber was confirmed to have relation to mechanical mechanism of cushioning layer. The highest mechanical strength value was obtained at 5 wt % of Kevlar ratio because of the highest cohesive force among recycled Kevlar, flame retardant polyester, and low‐melting point polyester fibers was provided at the blending ratio. The perforated high‐density flexible polyurethane foam composites panel was adhered with intra‐ply hybrid laminates with various areal densities on each face to form sandwich structural composites. The results revealed that perforation ratio and aperture significantly influenced the bursting and low‐velocity impact resistance behaviors of the perforated composites panel. Perforated composites with 10% perforation ratio and 4 mm aperture lead to maximum bursting strength of 437 N. Additional hybrid laminates significantly promoted the maximum bursting strength of the semiperforated hybrid composites by 212%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42288.     

Preparation and electrochemical properties of polyaniline/reduced graphene oxide composites

Polyaniline (PANI)/reduced graphene oxide (rGO) composites were synthesized by in situ oxidative polymerization of aniline on reduced graphene sheets. Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, transmission electron microscopy, and scanning electron microscopy were used to characterize the composites. The results indicated PANI/rGO composites were produced and contained covalent bonds between the functional groups of PANI and rGO. A uniform coating of PANI on the rGO sheets had a synergistic effect on the properties of the composites. The electrochemical properties of the PANI/rGO composites produced using different feed ratios of aniline to rGO were studied. The results showed that the composites exhibited a maximum specific capacitance of 797.5 F/g at 0.5 A/g and minimum charge transfer resistance of 0.98 Ω when the feed ratio of aniline to rGO was 2:1. These values were superior to those of pure PANI and rGO. The composites also displayed excellent cycling stability, with specific capacitance retention of 92.43% after 1000 cycles. These stable structural composites show promise for the development of new supercapacitor applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46103.     

Solid‐state synthesis and characterization of polyaniline/nano‐TiO2 composite

Polyaniline/nano‐TiO₂ composites with the content of nano‐TiO₂ varying from 6.2 wt % to 24.1 wt % were prepared by using solid‐state synthesis method at room temperature. The structure and morphology of the composites were characterized by the Fourier transform infrared (FTIR) spectra, ultraviolet‐visible (UV–vis) absorption spectra, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge measurement, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results from FTIR and UV–vis spectra showed that the composites displayed higher oxidation and doping degree than pure PANI. The XRD and morphological studies revealed that the inclusion of nano‐TiO₂ particles hampered the crystallization of PANI chains in composites, and the composites exhibited mixed particles from free PANI particles and the nano‐TiO₂ entrapped PANI particles. The galvanostatic charge–discharge measurements indicated that the PANI/nano‐TiO₂ composites had higher specific capacitances than PANI. The composite with 6.2 wt % TiO₂ had the highest specific capacitance among the composites. The further electrochemical tests on the composite electrode with 6.2 wt % TiO₂ showed that the composite displayed an ideal capacitive behavior and good rate ability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Modified polyaniline and its effects on the microstructure and antistatic properties of PP/PANI‐APP/CPP composites

Polypropylene (PP) composites that contain poly(aniline) (PANI) and ammonium polyphosphate crystalline form II (APP‐II) have both antistatic and flame‐retardant properties. In the present study, double anti‐functional PANI was prepared via in situ polymerization in the presence of APP‐II. Analysis of the Fourier transform infrared spectra demonstrated that PANI was synthesized successfully with APP‐II and that modified PANI (PANI‐APP) was obtained. Next, PP/PANI‐APP/chlorinated poly(propylene) (CPP) and PP/PANI/CPP composites were prepared. The results showed that the volume resistivity of the PP/PANI‐APP/CPP composite was at least 100 times less than that of the PP/PANI/CPP composite. The microstructures of the corresponding composites were investigated carefully by scanning electron microscopy and wide angle X‐ray diffraction. The areas of the conductive regions and the percentage crystallinity of PP in the PP/PANI‐APP/CPP composite were distinctly higher than those in the PP/PANI/CPP composite, i.e., by about 10% and 7%, respectively. In addition, experimental analyses of the limiting oxygen index and thermogravimetry showed that the PP/PANI‐APP/CPP composite had advantages compared with PP in terms of its flame‐retardant properties thermal stability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40732.