Preparation and characterization of UV‐curable ZnO/polymer nanocomposite films

A series of novel nano‐ZnO/polymer composite films with different ZnO contents was prepared through incorporation of pre‐made colloidal ZnO particles into monomer mixtures of urethane‐methacrylate oligomer and 2‐hydroxyethyl methacrylate, followed by ultraviolet (UV) radiation‐initiated polymerization. The colloidal ZnO nanoparticles with a diameter of 3–5 nm were synthesized from zinc acetate and lithium hydroxide in ethanol via a wet chemical method. In order to stabilize and immobilize the ZnO particles into the polymer matrix, the ZnO nanoparticles were further capped using 3‐(trimethoxysilyl)propyl methacrylate. Thermogravimetric analyses show that the ZnO nanoparticles were successfully incorporated into the polymer matrix and these ZnO/polymer composites have a good thermal stability. Transmission electron microscopy studies indicate the ZnO nanoparticles were uniformly dispersed in the polymer and they remained at the original size (3–5 nm) before immobilization. All nanocomposite films with ZnO particle contents from 1 to 15 wt% show good transparency in the visible region and luminescent properties. In addition, composite films with high ZnO content (>7 wt%) are able to absorb UV irradiation below 350 nm, indicating that these composite films exhibit good UV screening effects. Copyright © 2006 Society of Chemical Industry     

Insight of electrical behavior in ferroelectric‐semiconductor polymer nanocomposite films of PVDF/ZnSe and PVDF/Cu:ZnSe

Nanocomposite thin films (NCTF) of low‐dimensional ZnSe and copper doped ZnSe integrated poly(vinylidene fluoride) (PVDF) polymer were developed via simple solution casting method. Herein, ZnSe and Cu:ZnSe nanoparticles were synthesized through the chemical reduction technique. The obtained low‐dimensional nanoparticles and NCTFs were characterized by XRD, SEM/EDS, TEM, and FTIR analysis. Room temperature dielectric and ferroelectric characteristics of PVDF/ZnSe flexible NCTF exhibited superior dielectric and ferroelectric behavior with a high coercive field of 15.6 V. Whereas, the dielectric and ferroelectric characteristics were greatly diminished in the PVDF/Cu:ZnSe flexible NCTF was due to the conducting behavior of copper ions at the interface of the polymer network. These results indicated that the PVDF/ZnSe flexible NCTF will be a potential candidate for advanced electrical applications and device fabrication. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44983.     

Flexible electroactive PVDF/ZnO nanocomposite with high output power and current density

In the present study, a lightweight and flexible polyvinylidene fluoride (PVDF)/zinc oxide (ZnO) nanocomposite was prepared using a low-temperature phase-inversion process. The synergetic effect of low-temperature, phase-inversion, and the integration of ZnO nanoparticles primes on enhancing the electroactive polar β-phase in the nanocomposite. The transformation of the electroactive phase and its quantification were carried out using Fourier-transform infrared spectroscopy and wide-angle X-ray diffraction. The PVDF/ZnO piezoelectric polymer nanocomposite was utilized for energy harvesting application that showed a better electromechanical response of ca. 69 V (peak to peak) at ~1.6 N, 250 μW/cm² surface power density and 0.25 mA/cm² surface current density. The fabricated piezoelectric polymer nanocomposite is a possible candidate for superior energy scavenging applications for capturing human kinematics.     

Dielectric behavior of PVDF/POMA blends that have a low doped POMA content

The real (ε′) and imaginary (ε″) components of the complex permittivity of blends of PVDF [poly(vinylidene fluoride)] with POMA [poly(o‐methoxyaniline)] doped with toluenosulfonic acid (TSA) containing 1, 2.5, and 5 wt % POMA–TSA were determined in the frequency interval between 10² and 3 × 10⁶ Hz and in the temperature range from ?120 up to 120°C. It was observed that the values of ε′ and ε″ had a greater increase with the POMA–TSA content and with a temperature in the region of frequencies below 10 kHz. This effect decreased with frequency and it was attributed to interfacial polarization. This polarization was caused by the blend heterogeneity, formed by conductive POMA–TSA agglomerates dispersed in an insulating matrix of PVDF. The equation of Maxwell–Garnett, modified by Cohen, was used to evaluate the permittivity and conductivity behavior of POMA–TSA in the blends. A strong decrease was observed in POMA–TSA conductivity in the blend, which was bigger the lower the POMA–TSA content in the blend. This decrease could have been caused either by the POMA dedoping during the blend preparation process or by its dispersion into the insulating matrix. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 752–758, 2003     

Prediction of long‐term mechanical properties of PVDF/BaTiO3 nanocomposite

Low elastic modulus of polyvinylidene fluoride (PVDF) is a major drawback that can be compensated by adding nanoparticles. This work reports the long‐term mechanical behavior of PVDF nanocomposite containing BaTiO₃ nanoparticle that is evaluated by creep test. The nanocomposite morphology was characterized by scanning and transmission electron microscopy techniques. The dynamic mechanical analysis (DMA) was employed to study the viscoelastic behavior of nanocomposite in a wide range of temperatures and frequencies. According to the creep tests, nanocomposite reduced the rate of the creep compliance at different temperatures. Moreover, the creep compliance for the nanocomposite sample decreased slightly in comparison with neat PVDF. Comparing the Burger's model and experimental results, the elastic and viscous parameters revealed the exactly opposite behavior with increasing temperature. The effect of frequencies on storage moduli of samples was investigated based on time–temperature superposition (TTS) method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40596.     

Thermo‐electric behavior (PTC) of carbon black–containing PVDF/UHMWPE and PVDF/XL‐UHMWPE blends

This paper describes the structure and electrical performance of PTC/NTC (positive temperature coefficient/negative temperature coefficient) effects and their reproducibility upon healing/cooling cycles. The following three‐component blends were studied: PVDF/UHMWPE/CB, PVDF/XL‐UHMWPE/CB and γ‐irradiated compression molded plaques of these blends. Carbon black (CB) particles are attracted to the UHMWPE (ultra high molecular weight polyethylene) and XL (cross‐linked)UHMWPE particles, which constitute the dispersed phase in the PVDF (polyvinylidene fluoride) matrix, but practically cannot or only very slightly penetrate them because of their extremely high viscosity. A double‐PTC effect was exhibited by all unirradiated samples. Irradiation of compression molded PVDF/UHMWPE/CB plaques does not add to their already outstanding reproducibility, and it results In a wide single‐PTC effect. Irradiation of compression molded PVDF/XL‐UHMV/PE/CB plaque, slabilizes their structure upon heating/cooling cycles and thus makes them reproducible PTC/NTC materials, still exhibiting a double‐PTC effect. The carbon black concentrations studied in this report are extremely low (< 2 phr CB) in comparison to other literature reports.     

Preparation and characterization of PS‐PMMA/ZnO nanocomposite films with novel properties of high transparency and UV‐shielding capacity

High transparent and UV‐shielding poly (styrene)‐co‐poly(methyl methacrylate) (PS‐PMMA)/zinc oxide (ZnO) optical nanocomposite films were prepared by solution mixing using methyl ethyl ketone (MEK) as a cosolvent. The films were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis) spectra, high‐resolution transmission electron microscopy (HR‐TEM), and atomic force microscope (AFM). Cross‐section HR‐TEM and AFM images showed that the ZnO nanoparticles were uniformly dispersed in the polymer matrix at the nanoscale level. The XRD and FTIR studies indicate that there is no chemical bond or interaction between PS‐PMMA and ZnO nanoparticles in the nanocomposite films. The UV–vis spectra in the wavelength range of 200–800 nm showed that nanocomposite films with ZnO particle contents from 1 to 20 wt % had strong absorption in UV spectrum region and the same transparency as pure PMMA‐PS film in the visible region. The optical properties of polymer are greatly improved by the incorporation of ZnO nanoparticles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dielectric properties of Ag@C/PVDF composites

The core–shell Ag@C nanoparticles were prepared by hydrothermal method. The silver cores with diameters from 100 to 120 nm are each covered with a carbon shell about 60–80‐nm thick. Ag@C/poly(vinylidene fluoride) (PVDF) composites were prepared by the solution cast method. Transmission electron microscopy showed that the Ag@C core–shell nanoparticles were dispersed homogenously in the PVDF matrix with little agglomeration. The crystallization behavior and dielectric properties of the Ag@C/PVDF composites as a function of frequency and temperature were studied. The differential scanning calorimeter measurements showed that the crystallinity of the Ag@C/PVDF composites decreased with the increasing content of the Ag@C nanoparticles. The dielectric tests showed that the permittivity of the Ag@C/PVDF composites increased obviously over that of the pure PVDF with increasing content of Ag@C particles because of the enhanced interfacial polarization. The tan δ of the composites remained at a low level (～0.08 at 1000 Hz). Furthermore, the permittivity and the tan δ of the composites increased with increasing temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Size‐dependent optical properties of transparent,spin‐coated polystyrene/ZnO nanocomposite films

Zinc oxide (ZnO) nanoparticles are synthesized using a simple chemical method at room temperature. A variation in molar concentration of the precursor, potassium hydroxide, from 0.25 to 0.01 mol L^?1 is accompanied by a decrease in the average size of the nanoparticles. These nanoparticles are used for the preparation of polystyrene/ZnO nanocomposite films using the spin‐coating technique. These films are found to be highly transparent throughout the visible region and absorb UV light in the region from 395 to190 nm, almost covering the near and middle UV ranges (400 to 200 nm). This observation highlights the possible prospects of these films in UV shielding applications. The wavelength corresponding to the onset of UV absorption is found to be blue shifted with a decrease in size of the ZnO particles in the composite films due to confinement effects. The photoluminescence spectra of the composite films also change as a function of particle size. The emissions at longer wavelength due to defects and impurity‐related states in ZnO are almost quenched as a result of surface modification by the polymer matrix. The observed band‐gap enlargement with a decrease in size of the ZnO particles in the composite films is significant for band‐gap engineering of nanoparticles for various applications. Copyright © 2011 Society of Chemical Industry     

Preparation and characterization of UV-cured polyurethane acrylate/ZnO nanocomposite films based on surface modified ZnO

A series of polyurethane acrylate (PUA)/ZnO nanocomposite films with different ZnO contents were prepared via a UV-curing system. To ensure good dispersion in the PUA matrix, ZnO nanoparticles were modified with a silane coupling agent and confirmed by FT-IR analysis. The morphological structures, thermal properties, mechanical properties and water transfer properties of the prepared films were investigated as a function of their ZnO concentration. WAXD and SEM analyses showed that the surface-modified ZnO nanoparticles were homogeneously dispersed in the PUA matrix and the molecular ordering increased with increasing ZnO content. Compared with neat PUA, the hardness and elastic modulus in films increased from 0.03 to 0.056 GPa and from 2.75 to 3.55 GPa, respectively. Additionally, the water uptake and WVTR in the PUA/ZnO nanocomposite films decreased as the ZnO content nanoparticles increased, which may come from enhanced molecular ordering and hydrophobicity in films. UV light below approximately 450 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PUA matrix, indicating that these composite films exhibit good weather ability and UV-shielding effects. The enhanced physical properties achieved by incorporating modified ZnO nanoparticles can be advantageous in various applications, whereas the thermal stability of the composite films should be increased.     

Preparation and characterization of wood/styrene‐acrylonitrile copolymer/MMT nanocomposite

Wood polymer nanocomposite (WPNC) was prepared by impregnating Simul (Salmalia malabarica) wood with styrene‐acrylonitrile copolymer (SAN), glycidyl methacrylate(GMA), and a reactive polymerizable surfactant modified montmorillonite (MMT). The physical and mechanical properties of WPNC were investigated by using XRD, tensile tester, SEM, and FTIR. The polymer loading, dimensional stability, water uptake, mechanical property, and thermal stability were found to improve due to inclusion of MMT. SEM micrographs showed the presence of polymer and MMT into cell wall and cell lumen. FTIR analysis confirmed the presence of MMT and SAN in WPNC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Curing kinetics and thermal property characterization of o‐CFER/MeTHPA/O‐MMT nanocomposite

The kinetics of the cure reaction for a system of o‐cresol‐formaldehyde epoxy resin (o‐CFER), 3‐methyl‐tetrahydrophthalic anhydride (MeTHPA), N,N‐dimethyl‐benzylamine, and organic montmorillonite(O‐MMT) were investigated by means of X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD result indicates that an exfoliated nanocomposite was obtained. The analysis of DSC data indicated the behavior was shown in the first stages of the cure for the system, which could be well described by the model proposed by Kamal. In the later stages, the reaction is mainly controlled by diffusion, and diffusion factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics was predicted well over the entire range of conversion. Molecular mechanism for curing reaction was discussed. The thermal degradation kinetics of the system were investigated by thermogravimetric analysis (TGA), which revealed that with the increase of O‐MMT content, TG curves shift to higher temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3023–3032, 2006     

Preparation and characterization of nylon‐6/PPy/MMT composite of nanocomposite

Series of composites consisting of polypyrrole/montmorillonite nanocomposites in the matrix of Nylon6 has been synthesized and characterized in this work. The composites were processable, so that test samples were prepared by compression‐molding of the materials for electrical property measurements. Intercalated structures were confirmed by wide‐angle X‐ray diffraction and TEM studies for PPy/MMT nanocomposites. A two‐phase structure was determined for the fused samples consisting of two separated N6 and PPy phases by using scanning electron microscopy analyses. A conductivity threshold was measured at 15%(w/w) loading level of PPy in the composites. Electrical resistivity–temperature behavior of the samples was investigated and a resistivity peak was observed at 100°C for the samples. It was proved that the glass transition temperature of PPy around 100°C should be the responsible factor for the observed resistivity peak, as studied by thermogravimetic analysis and differential scanning calorimetry thermal methods. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

改性钛酸锶/PVDF复合材料介电性能研究

采用具有强络合能力的酒石酸在碱性溶液中对SrTiO3陶瓷颗粒进行表面改性,将改性后的SrTiO3颗粒与聚偏二氟乙烯(PVDF)经热压共混成型,制备出系列陶瓷/聚合物基复合材料,对改性SrTiO3/PVDF复合材料进行了介电性能分析。结果表明:添加了改性SrTiO3的复合材料比未改性SrTiO3复合材料的介电常数增加值达34%以上,同时,改性复合材料的介电损耗仍保持较低水平;随着改性SrTiO3在复合材料中含量的增加,介电常数也随之增加,介电损耗仍保持不变,改性后的陶瓷/聚合物复合材料表现出优异的综合介电性能。     

Preparation and Dielectric Properties of AGS@CuPc/PVDF Composites

GNS/PVDF, AGS/PVDF and AGS@CuPc/PVDF composites were prepared using hot press molding technique. The micromorphologies showed that the dispersion degree of the GNS in the matrix decreases in the following order: AGS@CuPc/PVDF > AGS/PVDF > GNS/PVDF. It could be attributed to AGS treated with copper phthalocyanine (CuPc) exhibit strongest interface bonding with PVDF, and acidification GNS (AGS) have stronger interface bonding with PVDF than GNS. GNS/PVDF composites showed a slight increase in dielectric constant and dielectric loss with the growing content of fillers. AGS/PVDF composites presented a better performance in dielectric constant than that of GNS/PVDF but with a much higher dielectric loss. Especially AGS@CuPc/PVDF three-phase composite displayed better dielectric properties than GNS/PVDF and AGS/PVDF composites, with a dielectric constant 327 and a dielectric loss 0.63 at 10 kHz. It could be attributed to the cooperation of well dispersion of conductive fillers and the electric barrier effects of CuPc.     

Synthesis and characterization of novel silver/L‐phenylalanine‐based optically active polyacrylate nanocomposite

Novel bioactive and optically active poly(N‐acryloyl‐L ‐phenylalanine) (PAPA) was synthesized by atom transfer radical polymerization. PAPA‐silver (Ag) nanocomposites have been successfully prepared via in situ reducing Ag⁺ ions anchored in the polymer chain using hydrazine hydrate as reducing agent in an aqueous medium. By controlling of the amount of Ag⁺ ions introduced, we have produced an organic/inorganic nanocomposite containing Ag nanoparticles with well controlled size. Nanocomposites were characterized by X‐ray diffraction (XRD), UV–Vis spectrophotometry, transmission electron microscopy, and Fourier transform infrared. XRD pattern showed presence of Ag nanoparticles. The PAPA/Ag nanocomposites with 1 : 10 silver nitrate (AgNO₃) : PAPA ratio revealed the presence of well‐dispersed Ag nanoparticles in the polymer matrix. All of these Ag nanoparticles formed are spherical and more than 80% of them are in the range of 15–25 nm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization behavior of PA‐6 clay nanocomposite hybrid

Polyamide‐6 (PA‐6)/clay (modified montmorillonite) hybrid was synthesized by melt blending at high shear stress. ²⁷Al‐NMR of solid state shows that the clay is not modified after melt blending. Using wide‐line ¹H‐NMR and TEM, it is demonstrated that the nanocomposite exhibits mainly an exfoliated structure. It is shown that the modified montmorillonite induces the crystallization of PA‐6 predominantly in γ‐form. The presence of clay in PA‐6 increases the polymer crystallization temperature, and decreases its melting point. These phenomena show that a certain number of interactions develop near the reinforcing material, and that the latter plays a particular role of nucleating agent. However, the crystallization is not spherulitic and the assumption of macromolecular orientation in the vicinity of the clay is demonstrated by the observations carried out in DSC and AFM. These particular properties of orientation will have a particular importance on the mechanical behavior of the nanocomposite material. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2416–2423, 2002     

Swelling behavior of novel protein‐based superabsorbent nanocomposite

A novel superabsorbent nanocomposite based on hydrolyzed collagen was synthesized by simultaneously graft copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) and acrylamide (AAm). Sodium montmorilonite (Na‐MMt) was used as clay. Methylenebisacrylamide (MBA) and ammonium persulfate (APS) were used as crosslinker and initiator, respectively. The effect of reaction variables such as nanoclay content, MBA and APS concentrations as well as the AMPS/AAm weight ratio on the water absorbency of nanocomposites was investigated. Although the water absorbency was decreased by increasing of MBA concentration, an optimum swelling capacity was achieved for clay, APS, and AMPS/AAm variables. The structure of nanocomposite was identified using FTIR spectroscopy, XRD patterns, and scanning electron microscopy graphs. The effect of swelling media comprising various dissolved salts and different pHs was studied. Also, water retention capacity was studied, and the results showed that inclusion of Na‐MMt nanoclay causes an increase in water retention under heating. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of a Zr‐containing silicate‐based epoxy‐functional polymer nanocomposite system

As a continuation of efforts to explore the potential of certain types of polymer nanocomposites to be successful candidates as dental restoration/adhesion materials, a Zr‐containing and organically modified silicate‐based material system with epoxy functionality was prepared by use of a sol–gel synthesis method, and UV light‐ and visible light (VL)‐curing processes. Comparative influences of the synthesis and processing parameters on the mechanical, thermal, and microstructural/nanostructural properties of the system were detailed. Zr‐containing species proved to more effectively catalyze the epoxy polymerization/crosslinking reactions than those containing Ti. Incorporation of Zr into the nanocomposite network led to significantly advanced mechanical properties. An elastic (Young's) modulus value of 23 MPa was achieved. The system with relatively high Zr content was successfully obtained, which also had higher thermal stability. Overall observations and results suggested that Zr content, and the UV light‐ or VL‐curing process could be capitalized on to modify the structure, and to improve the final properties of these material systems, which indicated a prospective opportunity for this material system to be utilized in dental restoration/adhesion applications. POLYM. ENG. SCI., 55:792–798, 2015. © 2014 Society of Plastics Engineers     

Preparation and characterization of semi‐interpenetrating network polystyrene/PVDF cation exchange alloy membranes

The polystyrene‐DVB/PVDF alloy particles were prepared by pulverizing the polymerization product of styrene/DVB/PVDF in DMF, and then sulfonated with concentrated sulfuric acid to gain the cation exchange alloy powder, which was directly thermoformed by a hot‐press machine to form the titled cation exchange alloy membranes with the structure of semi‐interpenetrating polymer network. The effects of the polystyrene‐DVB to PVDF mass ratio and the DVB content in the monomers on the physical and electrochemical properties of the prepared alloy membranes were investigated. While the Fourier transform infrared spectroscopy (FTIR) confirms the components of membranes, the scanning electron microscopy (SEM) reveals that the alloy membranes possess a uniform distribution of functional groups, and a more dense structure with the increases of DVB content and PVDF content. The optimal prepared membranes have the area electrical resistance values within 3.0–6.6 Ω·cm², obviously superior to the commercial heterogeneous cation exchange membrane, as well as the moderate water contents of 35–40% and the desirable permselectivity with a transport number more than 0.95. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1220‐1227, 2013