Effect of calcination temperature of TiO2 on the crystallinity and the permittivity of PVDF‐TrFE/TiO2 composites

Composite membranes of poly(vinylidene‐trifluoroethylene)/titanium dioxide (PVDF‐TrFE/TiO₂) were prepared by the solution cast method. The crystallization behavior and dielectric properties of the composites with TiO₂ calcined at different temperatures were studied. Transmission electron microscopy and X‐ray diffraction (XRD) results showed that the TiO₂ nanoparticles calcined at different temperatures were well dispersed in the polymer matrix and did not affect the structure of the PVDF‐TrFE matrix. XRD and differential scanning calorimeter measurements showed that the crystallinity of PVDF‐TrFE/TiO₂ composites increased as the addition of TiO₂ with different calcination temperatures. The dielectric property testing showed that the permittivity of PVDF‐TrFE/TiO₂ membrane increased rapidly with the increase of TiO₂ content and the calcination temperature of TiO₂ at constant TiO₂ content, but the dielectric loss did not change much. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Employment of ultrasonic waves for the preparation of PVA/TiO2‐BSA nanocomposites: Mechanical,thermal, and optical properties

The goal of this project is to obtain poly(vinyl alcohol) (PVA)/TiO₂‐bovine serum albumin (BSA) nanocomposite (NC) films in different weight percentages of modified TiO₂. For this purpose, to prevent the accumulation of nanoparticles (NPs) in the PVA matrix, the surface of the TiO₂ NPs was treated with the BSA molecules. To achieve this aim, ultrasonic waves were used as an environmentally friendly and green process that decrease the time of reactions, help better spreading of TiO₂ NPs and maintain dimensions of TiO₂ NPs in the nanoscale range. In the end, the features of the PVA/TiO₂‐BSA NC films were considered with a variety of techniques. The Fourier transform infrared spectroscopy, energy dispersive X‐ray, and X‐ray diffraction showed that the BSA was well placed on the surface of TiO₂ NPs. The thermal gravimetric analysis and UV‐visible results demonstrated that all the PVA/TiO₂‐BSA NC films have better thermal and optical properties than the pure PVA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46558.     

2D‐ and 3D Observation and Mechanism of Self‐Healing in Glass–Boron Composites

The self‐healing of a crack in a glass–boron composite has been observed by X‐ray nanotomography. It shows the occurrence of a healing effect within the bulk of the composite, despite of a limited oxygen access in the crack. This 3D tomographic observation offers new insights in the mechanism of healing, complementary to in situ high‐temperature environmental scanning electron microscopy. In addition, nano‐X‐ray fluorescence imaging, electron microprobe and solid‐state NMR gave evidence that the molten B₂O₃, produced by the oxidation of boron particles at 700°C, reacts with the glass matrix to form borosilicate compounds that also contribute to heal the crack. The high viscosity of B₂O₃ at 700°C leads to the formation of bridges between the walls of the crack, which limit oxygen diffusion. Thus, the B particle oxidation is not completed after a single healing cycle, meaning that several healing cycles can be obtained in a composite.     

Study on the properties of nano‐TiO2/polybutylene succinate composites prepared by vane extruder

Different proportions of nanoscale TiO₂ (nano‐TiO₂)‐filled polybutylene succinate (PBS) composites were prepared by vane extruder. The crystalline, thermal, dynamic viscoelastic, mechanical, and UV‐resistance properties of the composites were studied, and X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were conducted. Results show that the crystalline structure of the PBS composites did not change with TiO₂ addition. TiO₂ almost has no effect on the crystallization and melting behavior of PBS. Nevertheless, the introduction of TiO₂ has improved the thermal stability, tensile modulus, flexural modulus, and flexural strength of the PBS composites. The UV resistance of the composites has also been significantly enhanced with TiO₂ addition. POLYM. COMPOS., 35:53–59, 2014. © 2013 Society of Plastics Engineers     

Self‐cleaning Bombyx mori silk: room‐temperature preparation of anatase nano‐TiO2 by the sol–gel method and its application

The aim of this work was to obtain anatase nano‐TiO₂ by the sol–gel method at room temperature and to achieve self‐cleaning Bombyx mori silk fabrics. Nano‐TiO₂ sols based on an aqueous system and an ethanol system were prepared separately by the sol–gel method using tetrabutyl orthotitanate as a precursor at room temperature. Particle size analyses showed that nano‐TiO₂ particles in an aqueous system were much bigger and more variant than those in ethanol. X‐ray diffraction patterns revealed a pure anatase phase of nano‐TiO₂ in an aqueous system. Crystalline transformation of TiO₂ from anatase to rutile by photoradiation at ambient temperature was also proved. Thermogravimetric and differential scanning calorimetric analyses confirmed the phase transformation of nano‐TiO₂. A scanning electron microscope equipped with an energy‐dispersive spectrometer was used to investigate the surface morphology and elements of Bombyx mori silk fabrics. The contact angles with water, the kinetics of photocatalytic degradation of Methylene Blue, and decontamination of red‐wine‐stained fabrics under ultraviolet radiation demonstrated that the fabrics had good self‐cleaning properties and photoinduced hydrophilicity.     

Polymeric hybrid films with photocatalytic activity under visible light

The immobilization of photocatalysts on several kinds of substrates has been widely studied over the past few years, focusing mainly on improving its industrial application. In this work, novel hybrid films were prepared, employing TiO₂ P25, commercial ZnO or BiOI, synthetized through hydrothermal method and immobilized on poly(vinylidene fluoride) by the non‐solvent‐induced phase inversion technique. Subsequently, the prepared composites were evaluated by photodegradation of methylene blue (MB) under ultraviolet or visible light. The samples were also characterized by scanning electron microscope, thermo‐gravimetric analysis, attenuated total reflection–Fourier transform infrared spectroscopy, and X‐ray diffractometer analysis to improve comprehension of the composites' photocatalytic behavior. The degradation reaction of the contaminants exhibited pseudo‐first order kinetics in all samples, and achieved better performance when compared to simple photolysis. The recyclability of the hybrid films was also evaluated and proved that polymeric matrix is a promising material for the preparation of composites for photocatalysis applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46367.     

Mechanical and piezo‐resistive properties of styrene–butadiene–styrene copolymer covalently modified with graphene/styrene–butadiene–styrene composites

As novel piezoelectric materials, carbon‐reinforced polymer composites exhibit excellent piezoelectric properties and flexibility. In this study, we used a styrene–butadiene–styrene triblock copolymer covalently grafted with graphene (SBS‐g‐RGO) to prepare SBS‐g‐RGO/styrene–butadiene–styrene (SBS) composites to enhance the organic solubility of graphene sheets and its dispersion in composites. Once exfoliated from natural graphite, graphene oxide was chemically modified with 1,6‐hexanediamine to functionalize with amino groups (GO–NH₂), and this was followed by reduction with hydrazine [amine‐functionalized graphene oxide (RGO–NH₂)]. SBS‐g‐RGO was finally obtained by the reaction of RGO–NH₂ and maleic anhydride grafted SBS. After that, X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and other methods were applied to characterize SBS‐g‐RGO. The results indicate that the SBS molecules were grafted onto the graphene sheets by covalent bonds, and SBS‐g‐RGO was dispersed well. In addition, the mechanical and electrical conductivity properties of the SBS‐g‐RGO/SBS composites showed significant improvements because of the excellent interfacial interactions and homogeneous dispersion of SBS‐g‐RGO in SBS. Moreover, the composites exhibited remarkable piezo resistivity under vertical compression and great repeatability after 10 compression cycles; thus, the composites have the potential to be applied in sensor production. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46568.     

Preparation and properties of novel,flexible, lead‐free X‐ray‐shielding materials containing tungsten and bismuth(III) oxide

Novel, flexible, lead‐free X‐ray‐shielding composites were prepared with a high‐functional methyl vinyl silicone rubber (VMQ) matrix with W and Bi₂O₃ as filler materials. To verify the advanced properties of the lead‐free material, composites with the same mass fraction of PbO were compared. With the X‐ray energy ranging from 48 to 185 keV, the W/Bi₂O₃/VMQ composites exhibited higher X‐ray‐shielding properties. As the filler volume fraction decreased, the tensile strength, elongation, tear strength, and flexibility of the W/Bi₂O₃/VMQ composites increased. The Shore hardness of the W/Bi₂O₃/VMQ composites had a maximum value of 46.6 HA and was still very flexible. With decreasing filler volume fraction, the water‐vapor transmission performances of the W/Bi₂O₃/VMQ composites increased, and the W/Bi₂O₃/VMQ composites also showed better water‐vapor permeability. The heat‐transfer properties of the W/Bi₂O₃/VMQ composites increased with increasing W content, and when the W content exceeded 70 wt %, the thermal conductivity of the W/Bi₂O₃/VMQ material was about 70.45% higher than that of the PbO/VMQ composite. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43012.     

Thermal properties and crystallization behavior of bamboo fiber/high‐density polyethylene composites: Nano‐TiO2 effects

In this study, bamboo fiber/high‐density polyethylene (HDPE) composites were prepared, and the effects of nano‐TiO₂ on their thermal properties and crystallization behavior were investigated via thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the addition of nano‐TiO₂ improved the thermal stability and had a dual function in the crystallization behavior of the composites. On one hand, it functioned as a nucleating agent. The addition of 2 wt % nano‐TiO₂ promoted the crystallization, which caused the increase of the crystallization rate and crystallinity degree, as well as the micronization of the crystalline grain. On the other hand, intermolecular hydrogen bonds and covalent bonds were formed between nano‐TiO₂ and the polymer matrix, which hindered the crystallization of the composites. When the content of nano‐TiO₂ was continually increased, the inhibitory effect of the crystallization was gradually enhanced, which resulted in a decrease in the crystallization rate and crystallinity degree of the composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39846.     

Effect of neodymium‐doped titanium dioxide nanoparticles on the structural,mechanical, and electrical properties of poly(butyl methacrylate) nanocomposites

Nanocomposites based on neodymium‐doped titanium dioxide (Nd‐TiO₂)/poly(n‐butyl methacrylate) (PBMA) have been prepared by an in situ polymerization of butyl methacrylate monomer with varying concentrations of Nd‐TiO₂ nanoparticles. The resulting nanocomposites have been analyzed by ultraviolet (UV)–Visible spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and impedance analyzer (TGA). The results of UV and FTIR spectroscopy have indicated the interaction of nanoparticles with the PBMA matrix. Spherically shaped nanoparticles with an average size of 10–25 nm have been revealed in the TEM and their homogeneous dispersion, and interaction of polymer matrix has been confirmed by SEM and XRD studies. The thermal stability and glass transition temperature of the composites were significantly enhanced by the addition of nanoparticles. The AC conductivity and dielectric properties of nanocomposites have been found to be higher than pure PBMA, and the maximum electrical properties have been observed for 7 wt% composite. The reinforcing nature of the nanoparticles in PBMA has been reflected in the improvement in tensile strength measurements. The result indicated that the tensile strength of nanocomposites have greatly enhanced by the addition of Nd‐TiO₂ nanoparticles whereas the elongation at break decreases with the loading of nanofillers. To understand the mechanism of reinforcement, tensile strength values have been correlated with various theoretical modeling. The research has been found to be promising in the development of novel materials with enhanced tensile strength, dielectric constant, and thermal properties, which may find potential applications in energy storage and nanoelectronic devices. J. VINYL ADDIT. TECHNOL., 25:9–18, 2019. © 2018 Society of Plastics Engineers     

Fabrication of highly monodisperse CeO2@poly(methyl silsesquioxane) microspheres and their application in UV‐shielding films

Highly monodisperse CeO₂@poly(methyl silsesquioxane) (PMSQ) microspheres were successfully prepared by a facile chemical precipitation technique. The structures and properties of CeO₂@PMSQ were analyzed by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy techniques. We confirmed that the PMSQ microspheres were uniformly coated by CeO₂ nanoparticles, with about an 8 nm crystallite diameter. Then, CeO₂@PMSQ was incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate PVA/CeO₂@PMSQ composite films by the casting of homogeneous solutions. The thermal and optical properties of the composite films were investigated by thermogravimetric analysis and UV–visible spectroscopy. The results show the high UV‐shielding efficiency of the composites: for a film containing 2.5 wt % CeO₂@PMSQ microspheres, about 80% UV light at wavelengths between 200 and 360 nm was absorbed, whereas the optical transparency in the visible region still remained very high. The addition of CeO2@PMSQ microspheres improved the thermal stability of the PVA films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45065.     

Preparation,thermostability, and hydrophobic properties of TiO2/poly(dodecafluoroheptyl methacrylate) nanocomposites

Poly(dodecafluoroheptyl methacrylate) (PDFMA)/titanium dioxide (TiO₂) nanocomposites with high TiO₂ content were successfully prepared by emulsion polymerization process. Before polymerization, nano‐TiO₂ was pretreated by silane coupling agent. Surface groups and composition of the modified nano‐TiO₂ were characterized by Fourier transform infrared and X‐ray photoelectron spectra. The microstructure of nanocomposites was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the thermo‐stability and wetting behavior were also investigated in relation to the dosage of TiO₂. The results showed that the thermostability is improved with the increment of TiO₂ content while hydrophilic properties exhibit nonlinear variation with the content of TiO₂. The optimal percentage of TiO₂ content in the TiO₂/PDFMA nanocomposites is 30% that could lead to the higher thermostability and hydrophobicity properties of composites. The maximum water contact angle (WCA) of nanocomposites can reach 120° ± 1°. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44377.     

Enhanced thermal and mechanical properties of PW‐based HTPB binder using polystyrene (PS) and PS–SiO2 microencapsulated paraffin wax (MePW)

Polystyrene (PS) microencapsulated paraffin wax (MePW) and PS–SiO₂ MePW were used to improve the form‐stability of PW in hydroxyl‐terminated polybutadiene‐derived polyurethane (HTPB) binder. HTPB matrix containing different contents of PS MePW, PS–SiO₂ MePW, and PW were prepared. The chemical composition, crystallinity, microstructure, heat capacities, thermal stabilities, thermal reliabilities, leakage, and mechanical properties of the composites were compared using Fourier transforms infrared spectroscope, X‐ray diffractometer, scanning electronic microscope, differential scanning calorimeter, thermo‐gravimetric analyzer, thermal cycling test, leaking test, compression, and tensile tests, respectively. The results showed that the MePW/PW/HTPB composites were prepared without chemical reaction. The thermal stability and mechanical properties of PS–SiO₂ MePW/PW/HTPB increased more dramatically than that of PS MePW/PW/HTPB. With the increasing contents of MePWs, the PW leakage of the composites decreased, especially for PS MePW/PW/HTPB. Consequently, the MePW/PW/HTPB composites possess a potential application for PW‐based polymer‐bonded explosive system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46222.     

Preparation and radiation shielding properties of Gd2O3/PEEK composites

Gd₂O₃/PEEK (poly ether ether ketone) composites were prepared on a twin‐screw extruder by the incorporation of Gd₂O₃ as a shield against X‐ray to PEEK matrix. The influence of Gd₂O₃ addition and surface treatment of the particles with sulfonated PEEK (SPEEK) on the morphology, thermal and mechanical properties of the composites was investigated by SEM, DSC, TGA and tensile tests respectively. DSC results showed that both the crystallization temperature (T_c) and melting temperature (T_m) of the composites decreased compared with pure PEEK at random filler content, which suggested that Gd₂O₃ hindered the process of PEEK nucleation. The tensile modulus of the composites increased with addition of Gd₂O₃ and the strain to break decreased. But the tensile modulus and strength of modified series were always higher than that of unmodified ones at the same filler content. The X‐ray shielding properties of composites apparently improved with the increment of the Gd₂O₃. The X‐ray transmittance (A) of 45% S₄GPEEK reduced greatly by about three to eight times compared with PEEKs in all energy range measured. POLYM. COMPOS., 36:651–659, 2015. © 2014 Society of Plastics Engineers     

Preparation and catalytic properties of composites with palladium nanoparticles and poly(methacrylic acid) microspheres

Palladium (Pd) nanoparticles with different sizes are in situ synthesized by reduction of PdCl₂ with NaBH₄ as reductant in the presence of poly(methacrylic acid) (PMAA)microspheres. The obtained PMAA/Pd composites are characterized by Fourier transform infrared spectra, X‐ray diffraction, and Transmission electron microscopy. The catalytic activity of the PMAA/Pd composites is investigated using a model reaction, that is, reduction of p‐nitrophenol to p‐aminophenol. The reaction shows first‐order kinetics, and the reaction rate increases with increasing reaction temperature, p‐nitrophenol concentration, and loadings of Pd nanoparticles on PMAA microspheres. The PMAA/Pd composites exhibit good stability, ascribing to the Pd nanoparticles stabilized by PMAA microspheres. POLYM. COMPOS., 35:2251–2260, 2014. © 2014 Society of Plastics Engineers     

Preparation of nano‐TiO2/polystyrene hybride microspheres and their antibacterial properties

This study provided a facile method to prepare nano‐TiO₂/polystyrene hybride microspheres in ethanol solution. The formation of titanium dioxide (TiO₂) nanoparticles and hybrid microspheres were verified by FTIR, SEM, transmission electron microscopy, thermogravimetric analysis, and X‐ray powder diffraction. Monodispersed colloid TiO₂ nanoparticles with small particle sizes were obtained, and the average particle size could be effectively controlled from about 10 nm. The antibacterial activity of the organic microspheres and hybride microspheres was also investigated against Escherichia coli. They were able to efficiently inhibit the growth and the multiplication of E. coli under the UV. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ag@AgCl‐TiO2/organic rectorite/quaternized chitosan microspheres: An efficient and environmental photocatalyst

A plasmonic composite, Ag@AgCl‐TiO₂/OREC, was prepared by sol–gel combing calcination technique, precipitation, and photoreduction method. Then, Ag@AgCl‐TiO₂/OREC/QCS composite microspheres were fabricated by an emulsification/chemical crosslinking method using quaternized chitosan and Ag@AgCl‐TiO₂/OREC as scaffolds materials, potassium persulphate as initiator and N,N′‐methylenebisacrylamide as crosslinker. The resulting materials were characterized by Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), UV‐visible diffused reflectance spectra (UV–vis DRS), and scanning electron microscopy (SEM). SEM showed that the Ag@AgCl‐TiO₂/OREC/QCS composite microspheres had loose, rough surface, and spherical shape, with an average diameter of 15–45 μm. The Ag@AgCl‐TiO₂/OREC/QCS composite microspheres present good adsorption–photocatalytic activities in the degradation of methylene orange (MO) and 92.1% MO was degraded after irradiation for 180 min. The high photocatalysis activity was attributed to the combined results of the relative high adsorption capacity, loose structure, and the surface plasmon resonance of silver nanoparticles formed on the surface of AgCl. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44601.     

Preparation and Characterization of Bi3+‐TiO2 and its Photocatalytic Activity

Bi³⁺‐TiO₂ photocatalysts were prepared by doping bismuth ion into the TiO₂ structure in a sol‐gel process. The catalyst samples were then characterized by UV‐vis diffuse reflectance spectra (DRS), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Rodamine‐B (RhB) was used in this study as a model chemical with the aim of organic pollutants control. The photocatalytic degradation of RhB demonstrated that an optimal loading of bismuth 0.7 at. % achieved the highest photodegradation rate, with the rate constant increasing by a factor of 3.89 over neat TiO₂ (P25) under UV illumination (λ ≥ 320 nm). The degradation of p‐nitrobenzonic acid (pNBA) was also examined to prevent/preclude/exclude/ the photosensitization pathway. GC‐MS results show that pNBA can be effectively degraded and minerized to small molecules, such as quinone, acetic acid and formic acid.     

Effect of TiO2 on thermal and adhesive characteristics of poly(imide siloxane)/TiO2 hybrid films

A novel poly(imide siloxane)/titania (PIS/TiO₂) hybrid film was fabricated by sol‐gel process via in situ formation of TiO₂ within PIS matrix. Poly(amic acid siloxane) (PAAS) was prepared from 4,4′‐oxydiphthalic anhydride, 2,2‐bis [4‐(4‐aminophenoxy) phenyl] propane, and α,ω‐bis(3‐aminopropyl)polydimethylsiloxane (APPS). Chelating agent, acetylacetone, and catalyst‐free polymerization were used to reduce the rate of hydrolysis of titanium alkoxide in the PAAS. X‐ray photoelectron spectroscopy data showed that the presence of APPS promotes the Ti surface composition of PIS/TiO₂ hybrid film. The effects of TiO₂ and APPS contents on the characteristics of surface, thermostability, coefficient of thermal expansion (CTE), and the strength of adhesion were investigated. The presence of TiO₂ on the surface of the hybrid films enhanced the adhesive strength at the interface of PIS/TiO₂ hybrid film and copper foil. When more TiO₂ was incorporated into the PIS matrix, the PIS/TiO₂ hybrid film exhibited lower CTE while retaining favorable mechanical and thermal properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characterization and conductivity studies of nanocomposite films with polymer networks containing polyaniline‐alginate/titanium dioxide

Polyaniline nanocomposite films were chemically synthesized in the presence of alginate template by varying the concentration of TiO₂ in the composites. Characterization of the composite samples by FTIR, UV‐Vis spectra (UV), and X‐ray diffraction (XRD) indicates the formation of polyaniline‐alginate/titanium dioxide (PAT) composites. The morphology analysis by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) also supports the formation of the composites. Temperature‐dependent DC conductivity of the polyaniline‐alginate (PA) and PAT composites was studied in the range of 300 ≤ T ≤ 500 K. UV‐Vis and FTIR spectral studies reveal that the alginate is a good template for the chemical interaction between polyaniline and TiO₂, which suggests that the micelles formed by the anilinium‐alginate cations containing TiO₂ are responsible for the transport properties of the PAT composites. POLYM. COMPOS., 31:1754–1761, 2010. © 2010 Society of Plastics Engineers.