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1.
The effect of the addition of an ester of montanic acid with multifunctional alcohols in the effectiveness of the dispersion and compatibility of TiO2 nanoparticles when included as filler in poly(ethyleneterephthalate) for composite production is studied through the study of the non-isothermal crystallization by differential scanning calorimetry (DSC). The application of the Avrami method enables to evaluate the compatibility and the level of dispersion/aggregation of the nanofiller in the poly(ethyleneterephthalate) by the analysis of the temperature and enthalpy of crystallization, the kinetic parameters and the half-crystallization time.  相似文献   

2.
The effect of untreated and tri-n-octylphosphine oxide (TOPO) surface-treated TiO2 nanoparticles when included as filler in poly(ethylene terephthalate) on its compatibility, non-isothermal crystallization behavior, viscoelastic transitions and cold crystallization has been studied. The effectiveness of the surface treatment has been studied using infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA). The effect of the untreated and surface-treated nanofiller content in the polymer, added by an extrusion process, on the non-isothermal crystallization has been studied by differential scanning calorimetry (DSC). The influence on the viscoelastic transitions and cold crystallization of PET nanocomposites has been studied through thermomechanical analysis (TMA). The surface treatment and the concentration of nanofiller influence the non-isothermal crystallization behavior, the viscoelastic transitions and the cold crystallization of the PET nanocomposites, enables us to evaluate the compatibility and the level of dispersion/aggregation of the nanofiller in the poly(ethylene terephthalate).  相似文献   

3.
Poly(ethylene terephthalate) (PET) is an important industrial material and has been widely applied in consumer products. Due to its slow crystallization rate, nanoparticles are incorporated into PET to function as heterogeneous nucleating agents. In this study, the non-isothermal crystallization behavior of recycled PET-silicon nitride (Si3N4) nanocomposites was investigated by differential scanning calorimetry (DSC). In the general analysis of the non-isothermal crystallization curves, it was found that the Si3N4 nanoparticles could effectively accelerate the nucleation of PET, but the crystal growth rate was slowed down when the Si3N4 content was more than 1 wt%. This might be attributed to the interaction between the PET chains and the surface-treated Si3N4 nanoparticles. Results obtained from Avrami and Mo treatments agreed well with the general analysis. Application of the Kissinger method and isoconversional method of Flynn-Wall-Ozawa also showed that Si3N4 nanoparticles had a good nucleation effect on the crystallization of PET, and the crystal growth was hindered by Si3N4 when the particle loading is higher than 1 wt%.  相似文献   

4.
Poly(ethylene terephthalate) (PET) has been mixed with fluorite (CaF2) particles to obtain micro- and nano-composites aiming to obtain a hybrid multifilament. In first term, the use of two montanic waxes and an amide wax as dispersing agents towards the compatibilization of the inorganic and organic components of the CaF2/PET composite were considered. To do this, non-isothermal crystallization studies by differential scanning calorimetry have been carried out. Moreover, the influence of the CaF2 particle size and concentration on the thermal properties of the system have been also studied by this technique. Finally, the extrapolation of the results has materialised as a novel PET/CaF2 hybrid multifilament. Thermal and mechanical properties and molecular weight of the multifilament have been as well evaluated.  相似文献   

5.
There is a growing interest in the development of nanocomposites consisting of organic polymers and TiO2 or amorphous SiO2 nanoparticles. These nanoparticles may be released from nanocomposites. There is evidence that amorphous SiO2 and TiO2 nanoparticles can be hazardous. Thus, in the design of nanocomposites with such nanoparticles, hazard reduction extending to the full nanocomposite life cycle would seem a matter to consider. Options for hazard reduction include: changes of nanoparticle surface, structure or composition, better fixation of nanoparticles in nanocomposites, including persistent suppression of oxidative damage to polymers by nanoparticles, and design changes leading to the release of relatively large particles.  相似文献   

6.
Transparent organic-inorganic nanocomposites were successfully synthesized from sulfonic acid-modified poly(bisphenol A carbonate) (SPC) and TiO2 or ZrO2 nanoparticles. The dispersibility of nanoparticles was significantly improved by both the surface treatment of nanoparticles with phosphoric acid 2-ethylhexyl esters (PAEH) and the introduction of a sulfonic acid moiety into the PC chain. It was found that in some cases, crystallization of the matrix caused a reduction in transparency. Efficient dispersion of nanoparticles and the absence of crystallization resulted in highly transparent nanocomposites with up to 42 wt% TiO2 and 50 wt% ZrO2 nanoparticles. The refractive indices of the nanocomposites based on SPC increased with the increasing amount of nanoparticles. Theoretical equation based on Maxwell-Garnett effective medium theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The prepared nanocomposites had lower thermal stability than the host matrix polymers.  相似文献   

7.
The extensional rheology and dispersion behavior of high impact polystyrene (HIPS) and HIPS/TiO2 nanocomposites prepared by melt‐compounding were investigated. The influence of ethylene‐vinyl acetate (EVA) copolymer on the extensional rheology of HIPS/TiO2 masterbatches was also researched. The rheological experiments investigated with Rosand Presicion Rheometer confirmed that the HIPS/TiO2 masterbatches, the HIPS/EVA/TiO2 masterbatches and the HIPS/TiO2 nanocomposites with low TiO2 loading shown different extensional rheology in comparison to the pure HIPS. Field‐emission scanning electron microscopy (FE‐SEM) shown the dispersion morphology of TiO2 nanoparticles in HIPS based nanocomposites and indicated the influence of TiO2 dispersion behavior on the unusual extensional rheology of HIPS nanocomposites.  相似文献   

8.
Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles (PANI-TiO2 ) were characterized with the FT-IR, XRD, SEM and TEM techniques. Results confirmed that PANI was grafted successfully on the surface of TiO2 nanoparticles, therefore agglomeration of nanoparticles decreased dramatically. Polyvinyl chloride nanocomposites filled with 1 wt% 5 wt% of PANI-TiO2 and TiO2 nanoparticles were prepared via the solution blending method. PVC nanocomposites were analyzed with FT-IR, XRD, SEM, TG/DTA, DSC and tensile test techniques. Effect of PANI as surface modifier of nanoparticles was discussed according to the final properties of PVC nanocomposites. Results demonstrated that deposition of PANI on the surface of TiO2 nanoparticles improved the interfacial adhesion between the constituents of nanocomposites, which resulted in better dispersion of nanoparticles in the PVC matrix. Also PVC/PANI-TiO2 nanocomposites showed higher thermal resistance, tensile strength and Young’s modulus compared to those of unfilled PVC and PVC/TiO2 nanocomposites.  相似文献   

9.
Au改性TiO2纳米复合物对人结肠癌细胞的光催化杀伤作用   总被引:2,自引:0,他引:2  
许娟  陈智栋  孙毅  陈春妹  江志裕 《化学学报》2008,66(10):1163-1167
提出了通过TiO2表面修饰纳米Au的方法来提高纳米TiO2光催化杀伤癌细胞的效率. 采用化学还原法合成了Au改性的TiO2 (Au/TiO2)纳米复合物, 并研究了不同掺杂量(1 wt%, 2 wt%, 4 wt%)的Au/TiO2对人结肠癌LoVo细胞的光催化杀伤效应. 结果显示, Au的掺杂大大地提高了TiO2纳米粒子光催化杀伤结肠癌LoVo细胞的效率, 而且Au掺杂量的高低影响Au/TiO2光催化杀伤癌细胞的效率, 掺金量为2%的Au/TiO2对结肠癌LoVo细胞具有最高的光催化杀伤效率. 在光强为1.8 mW/cm2的紫外灯(λmax=365 nm)下光照110 min, 50 μg/mL掺金量为2%的Au/TiO2能够杀死所有的癌细胞, 而同样浓度的TiO2只能杀死70%的癌细胞.  相似文献   

10.
Inorganic dielectrics encapsulated in an organic matrix are showing excellent promise as novel dielectric materials. In this work, firstly highly organized crystalline nanoparticles of rutile TiO2 were synthesized by acid hydrolysis of titanium isopropoxide at room temperature. Then we developed a novel dielectric material consisting of highly organized rutile TiO2/polyaniline (PAni) nanocomposites by in-situ chemical oxidative polymerization. The structural, morphological, conducting, and dielectric properties of the rutile TiO2/PAni nanoparticles have been evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution-transmission emission microscopy (HR-TEM), four-point probe technique, CV (Capacitance versus Voltage), and Impedance analyzer. The nanocomposites show 70 times higher permittivity compared to rutile nanoparticles and much higher compared to anatase/PAni (ES) nanocomposites at 10 MHz. Large interfacial polarizations, nanostructure, and dopant levels are the key factors for the large dielectric constant of the nanocomposites. The rutile/PAni (ES) nanocomposites might see potential uses in super-capacitors, gate dielectric in transistors, and capacitive-type gas sensors.  相似文献   

11.
Surface modified TiO2 nanoparticles dissolved in toluene were encapsulated in PMMA by in situ radical polymerization of methyl methacrylate initiated by 2,2′-azobisisobutyronitrile. The surface modification of the TiO2 nanoparticles (average diameter of 4.5 nm) was achieved by the formation of a charge transfer complex between TiO2 nanoparticles and 6-palmitate ascorbic acid. The surface modified TiO2/nanoparticles were characterized using UV−Vis and FTIR spectroscopy, while the obtained polymer nanocomposites were characterized using reflection and 1H NMR spectroscopy, as well as gel permeation chromatography. The influence of the TiO2 nanoparticles on the thermal properties of the PMMA matrix was investigated using thermo-gravimetric analysis and differential scanning calorimetry. The glass transition temperature of the polymer was not influenced by the presence of the nanoparticles while the thermal stability was significantly improved.  相似文献   

12.
The influence of TiO2 nanoparticles on the thermal degradation of poly(methyl methacrylate) (PMMA) was investigated by TGA. The studied materials were characterized by Py-GC-MS, TEM, SEM, TGA, DSC and TGA-MS. The PMMA-TiO2 nanocomposites were prepared by melt blending with different (5, 10, 15 and 20 wt% TiO2) loadings. According to TGA results and to the activation energy (determined by the model-free isoconversional method of Vyazovkin), the incorporation of 5 wt% of TiO2 nanoparticles into PMMA stabilizes it by more than 40 °C. However, for higher loading contents, a catalytic effect on the thermal decomposition was observed which increased with the oxide content. The results obtained by Py-GC-MS showed clearly that TiO2 increases the formation of methanol, methacrylic acid and propanoic acid methyl ester during the degradation of PMMA. This catalytic effect could be explained through the interaction of the methoxy group of the methacrylate function with the hydroxyl groups present at the surface of the oxide particles.  相似文献   

13.
《Thermochimica Acta》2004,414(2):137-143
The kinetics of nanocrystallization in amorphous TiO2 has been studied in non-isothermal conditions by DSC. It was found that this process could be well described by standard Johnson-Mehl-Avrami-Kolmogorov (JMA) model with kinetic exponent m≅1. The kinetic parameters were calculated by simultaneous analysis of experimental data taken at different heating rates. These parameters were used as a basis for prediction of crystallization kinetics in isothermal conditions. The agreement between the JMA model prediction and experimental data depends on the method of preparation of amorphous TiO2.  相似文献   

14.
Na+ complex with the dibenzo-18-crown-6 ester was used as a template to synthesize mesoporous titanium dioxide with the specific surface area 130–140 m2/g, pore diameter 5–9 nm and anatase content 70–90%. The mesoporous TiO2 samples prepared were found to have photocatalytic activity in CuII, NiII and AgI reduction by aliphatic alcohols. The resulting metal–semiconductor nanostructures have remarkable photocatalytic activity in hydrogen evolution from water–alcohol mixtures, their efficiency being 50–60% greater than that of the metal-containing nano-composites based on TiO2 Degussa P25.The effects of the thermal treatment of mesoporous TiO2 upon its photocatalytic activity in hydrogen production were studied. The anatase content and pore size were found to be the basic parameters determining the photoreaction rate. The growth of the quantum yield of hydrogen evolution from TiO2/Ag0 to TiO2/Ni0 to TiO2/Cu0 was interpreted in terms of differences in the electronic interaction between metal nanoparticles and the semiconductor surface. It was found that there is an optimal metal concentration range where the quantum yield of hydrogen production is maximal. A decrease in the photoreaction rate at further increment in the metal content was supposed to be connected with the enlargement of metal nanoparticles and deterioration of the intimate electron interaction between the components of the metal–semiconductor nanocomposites.  相似文献   

15.
We report on the stability of titanium dioxide nanoparticles suspended in various aqueous solutions with and without the presence of a model organic contaminant—salicylic acid. The stability of the suspended nanoparticles was revealed by measuring the isoelectric point by means of zetapotential scans and measuring the growth kinetics of the hydrodynamic particle size by means of dynamic light scattering (DLS) under different pH conditions. Aggregated nanoparticle sizes were also examined using atomic force microscopy. It was found that salicylic acid had a dramatic impact on the aggregation behavior of TiO2 nanoparticles, suggesting that salicylic acid adsorbs to TiO2 nanoparticles surfaces.  相似文献   

16.
We have demonstrated a facile approach for fabricating graphene quantum dots–TiO2 (GQDs–TiO2) nanocomposites by a simple physical adsorption method. Compared with pure GQDs and TiO2 nanoparticles (NPs), the as-prepared GQDs–TiO2 nanocomposites showed enhanced photoelectrochemical (PEC) signal under visible-light irradiation. The photocurrent of GQDs–TiO2/GCE was nearly 30-fold and 12-fold enhancement than that of GQDs/GCE and TiO2/GCE, respectively, which was attributed to the synergistic amplification between TiO2 NPs and GQDs. More interestingly, the photocurrent of GQDs–TiO2 nanocomposites was selectively sensitized by dopamine (DA), and enhanced with the increasing of DA concentration. Further, a new PEC methodology for ultrasensitive determination of DA was developed, which showed linearly enhanced photocurrent by increasing the DA concentration from 0.02 to 105 μM with a detection limit of 6.7 nM (S/N = 3) under optimized conditions. This strategy opens up a new avenue for the application of GQDs-based nanocomposites in the field of PEC sensing and monitoring.  相似文献   

17.
The present article embraces the photocatalytic oxidation (PCO) of three selected cyclohexyl alcohols namely cyclohexylmethanol (1), 2-cyclohexylethanol (2) and 1-cyclohexylethanol (3) using nanoparticles titanium dioxide (TiO2-P25) as a semiconductor photocatalyst in acetonitrile under aerated conditions. The photocatalytic experiments showed moderate conversion ratios (55.2%, 51.8% and 60.3%, respectively). The primary photocatalytic oxidation products are the corresponding aldehydes or ketones and acids. The photocatalytic oxidation products were identified mainly by GC and GC/MS techniques using authentic samples. Formation of electron–hole pair at the surface of the semiconductor nanoparticles followed by oxidation reaction was the suggested mechanism. A first-order kinetic model was observed for the photocatalytic oxidation of the investigated alcohols and the rate constants were calculated.  相似文献   

18.
宋义虎 《高分子科学》2013,31(2):325-332
Nano-sized rod-like titanium dioxide (TiO2) filled rigid poly(vinyl chloride) (PVC) nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr (parts per hundreds of resin) could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness.  相似文献   

19.
TiO2 nanoparticles incorporated with CuInS2 clusters were prepared in a solvothermal process and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersion X-ray analysis (EDX). Compared with pure TiO2 nanoparticles, the TiO2 nanoparticles incorporated with CuInS2 clusters display higher photocatalytic activity with 99.9% of degradation ratio of 4-nitrophenol after 2 h irradiation. In order to investigate the effect of the CuInS2 clusters on the photocatalytic activity of TiO2 nanoparticles, diffuse reflectance UV–Vis spectra (DRS), photoluminescence (PL) spectra, and photocurrent action spectra were measured. The results indicate that the enhanced photocatalytic activity is probably due to the interface between TiO2 and CuInS2 as a trap of the photogenerated electrons to decrease the recombination of electrons and holes.  相似文献   

20.
Abstract

Vegetable oil based environmentally friendly polyurethane-TiO2 nanocomposite coatings have been synthesized by using sunflower oil derived diol, toluene diisocyanate and TiO2 nanoparticles. The chemical structure was confirmed by FTIR and NMR techniques while physico-chemical testing was carried out by standard laboratory methods. Physico-mechanical and anticorrosive tests of the coatings (in different corrosive media) have been investigated by standard methods. In addition to this the morphology and thermal stability behavior of the coatings have been carefully investigated by different techniques like XRD, TEM, TGA/DTG and DSC. The comparison of the performance of nanocomposites with the respective virgin polyurethane coatings reveals that the dispersion of nanoTiO2 enhanced the mechanical, corrosion and thermal stability behavior of the polymer. The synthesized nanocomposites can be used safely upto 250–275?°C. These sunflower oil derived polyurethane nanocomposites can be used in the world of protective coatings, as an alternative of petroleum derived corrosion protective coating materials.  相似文献   

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