用微量-热分析(μTA)表征聚合物膜

微量－热分析是一种结合原子力显微镜显示能力和热分析表征能力的崭新技术。它以原子力显微镜显示材料的形貌、热传导和热扩散的区域分布，并以微量－热机械分析及微量－调幅热分析测量材料相应位置的物理及化学性质变化     

Fast space charge behavior in heat‐treated polypropylene films

In this study, the characterization of the short‐circuit current within hundreds of nanoseconds is proposed to study the effect of heat treatment on fast space charge behavior in the polarized biaxially oriented polypropylene (BOPP) films. The BOPP films were cooled either quickly or slowly during the sample preparation. The damped oscillating feature was found in the short‐circuit current of all the polarized film samples, but the periods of the oscillating current for the samples prepared by fast cooling rate decrease faster. Bipolar space charge injection in the polarized BOPP films was observed by the thermal pulse (TP) measurement. The variation feature of the short‐circuit current was considered to be associated with the varying fast space charge behavior, which depended on the varying structural traps modified by the heat treatment during the sample preparation. The sample subjected to fast cooling process was with relatively shallow trap level revealed by the thermally stimulated current method, which led to higher mobility of the escaping charge in the sample. The TP measurements were utilized to analyze space charge features in the polarized BOPP films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42235.     

Through-thickness analysis of the skin layer thickness of multi-layered biaxially-oriented polypropylene films by micro-thermal analysis

A novel method is presented for the determination of the thickness of a polymer layer on a solid substrate by through-thickness local thermal analysis (LTA) measurements using a micro-thermal analyser (μTA). The feasibility of the method is illustrated for a poly(methyl methacrylate) film spin-cast on a silicon wafer. Subsequently the method is applied to determine the skin layer thickness of multi-layered biaxially-oriented polypropylene (BOPP) films. Although the melting temperatures of skin and core layer are only 15 °C different, it proved to be possible to determine the skin layer thickness. The film thickness obtained by μTA correlates well with the thickness observed by transmission electron microscopy (TEM) in a 0.1-1.6 μm range. The method is shown to be accurate, robust, and fast.     

Analysis of polymeric composite interphase regions with thermal atomic force microscopy

Previous work on the characterization of interphase regions in thermosetting composite systems has focused on the inference of an interphase layer from effects noticed through macroscale mechanical and thermal testing. With the development of atomic force microscopy and active thermal probes for this technique, it is now possible to examine material thermal properties on a much smaller scale. Variations in microscale thermal properties of an aerospace‐grade thermosetting resin system were evaluated for carbon and glass fiber reinforcement, using the modulated local thermal analysis mode of a TA Instruments 2990 μTA. The variations observed clearly demonstrate the presence of a soft interphase layer in the glass material and underline the importance of fiber–matrix interactions during the formation of the interphase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1643–1649, 2001     

Flexible conductive graphene/poly(vinyl chloride) composite thin films with high mechanical strength and thermal stability

The fabrication and characterization of ultrathin composite films of surfactant-wrapped graphene nanoflakes and poly(vinyl chloride) is described. Free-standing composite thin films were prepared by a simple solution blending, drop casting and annealing route. A significant enhancement in the mechanical properties of pure poly(vinyl chloride) films was obtained with a 2 wt.% loading of graphene, such as a 58% increase in Young’s modulus and an almost 130% improvement of tensile strength. Thermal analysis of the composite films showed an increase in the glass transition temperature of the polymer, which confirms their enhanced thermal stability. The composite films had very low percolation threshold of 0.6 vol.% and showed a maximum electrical conductivity of 0.058 S/cm at 6.47 vol.% of the graphene loading.     

Effect on wettability of the topography and oxidation state of biaxially oriented poly(propylene) film

Surface topography and surface chemistry heterogeneity are widely accepted as causes of contact angle hysteresis. Contact angle hysteresis occurs on essentially all industrial polymer films. Four unmodified and flame-treated biaxially oriented poly(propylene) (BOPP) films produced from the same poly(propylene) base resin, but differing in surface topography and orientation, were characterized by measurement of the advancing and receding contact angles of water and diiodomethane, by atomic force microscopy (AFM) and by x-ray photoelectron spectroscopy (XPS). Contact angle hysteresis was much larger on flame-treated samples than on untreated samples even though some of the untreated films have significantly different topography at the nanoscale.     

Plasma‐induced surface modification and adhesion enhancement of polypropylene surface

Unoriented (UPP) and biaxially oriented (BOPP) polypropylene films were treated under radio frequency plasma of air, nitrogen, oxygen, and ammonia. Surface modification of polypropylene films was investigated by using surface energy measurement and attenuated total reflection (ATR)‐FTIR spectroscopy. Surface energy of air and nitrogen plasma‐treated polypropylene film increased for shorter treatment time and then decreased and attained an equilibrium value. Such changes in surface energy were not observed for oxygen and ammonia plasma‐treated polypropylene film, which increased to an equilibrium value. ATR‐FTIR studies revealed characteristic differences in the absorption spectra for short‐duration and long‐duration treatments. From the relative intensity change in the C—H stretching vibration, the mechanism of surface chemical reaction could be inferred. Studies regarding the durability of surface modification due to plasma treatment were evaluated by investigating surface energy of samples aged for 2 months. Treated films subjected to peel strength measurement showed improvement in bondability for UPP and BOPP film by hydrophilic surface modification accompanied by surface crosslinking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 925–936, 2002     

Polymer structure and morphology of low density polyethylene filled with silica nanoparticles

The effect of silica nanoparticles on structure and morphology of low density polyethylene (LDPE) was investigated. To prepare the nanocomposites, SiO₂ nanoparticles were dispersed in a LDPE with cryogenic high‐energy ball milling (HEBM). Films of these nanocomposites with different loads (0%, 1.8%, 2.3%, 3.3%, 7.9%, 16.5% wt/wt) were obtained by hot pressing. Differential scanning calorimetry (DSC) was used to study the nonisothermal melting and crystallization of the films. The morphological characterization was done by atomic force microscopy (AFM). To determine the most representative periodical spacing associated to the LDPE crystallites, a new approach based on the first moment of the frequency distribution obtained from the fast Fourier transform of the AFM phase contrast images was used. Ultracryomicrotomed surfaces of the nanocomposites revealed an efficient dispersion of the nanoparticles throughout the polymer bulk. Although HEBM promotes the formation of the metastable monoclinic phase in the LDPE, nanocomposites in the form of films did not show important differences in their thermal and morphological characteristics, suggesting that there are not high interactions between the polar nanoparticles and the nonpolar polymer and that thermal treatment is enough to eliminate the specific microstructure induced by HEBM. POLYM. COMPOS., 33:2009–2021, 2012. © 2012 Society of Plastics Engineers     

Synthesis,magnetic and transport properties of oxygen-free CrN ceramics

In the literature, CrN is usually synthetized as thin films and often contains impurities such as oxygen or Cr₂N. We successfully prepared pure CrN powder by ammonolysis of anhydrous chromium (III) chloride, which was confirmed by X-ray diffraction analysis (XRD) and SEM-EDS. CrN ceramics were then prepared by classical ceramic route (CCR) and by spark plasma sintering (SPS) at different sintering conditions. Transport properties (Seebeck coefficient, electrical resistivity and thermal conductivity) were measured in the range 2–600 K and the magnetic behavior was examined by SQUID. Above the room temperature thermal conductivity was obtained by laser flash analysis (LFA). Thermal stability and thermodynamic characteristics were probed by simultaneous thermal analysis (STA). Transport properties are strongly affected by the fabrication process and the resulting figure of merit (ZT) is surprisingly high. CrN has big potential as a new high temperature thermoelectric material.     

Preparation and characterization of hybrid membranes for fuel cell applications: hydrogenated styrene–butadiene rubber filled with alkyl,phenyl or tolyl sulfonated silica

Polymers with ionic groups attached (ionomers) are indispensable electrolyte materials for proton exchange membrane fuel cells. Nafion^®, a widely used membrane, has many disadvantages: price, high methanol crossover and conductivity loss at temperatures above 80 °C. This work reports the preparation and characterization of hybrid membranes, alternatives to commercial Nafion, based on blends of hydrogenated polybutadiene‐block‐polystyrene copolymer and organophilized silicas. The films obtained were crosslinked to improve mechanical stability, and heterogeneously sulfonated to convert them to proton‐conducting systems. Structural characterization involved differential scanning calorimetry and dynamic mechanical analysis to determine their thermal and mechanodynamical transitions, attenuated total reflectance Fourier transform infrared spectroscopy for verifying the introduction of sulfonic groups and scanning electron microscopy linked with energy‐dispersive X‐ray analysis for obtaining more information on the location and distribution of silica within the polymer matrix. Electrical characterization was made using electrochemical impedance spectroscopy, giving high conductivity values of ca 2.6–5.8 × 10^?2 S cm^?1. Also, methanol crossover was determined: low permeabilities were found. The results showed that sulfonation of the styrene rings had occurred effectively. Conductivities were higher and methanol crossover lower than for Nafion for all samples. Copyright © 2011 Society of Chemical Industry     

Synthesis and studies of exceptionally crystalline polyaniline thin films

Highly crystalline camphor sulfonic acid (CSA)‐doped polyaniline (PANI) thin films cast from m‐cresol and N‐methylpyrrolidone (NMP) were investigated. PANI powder prepared by chemical oxidative polymerization subjected to doping–de‐doping–re‐doping procedures was cast into thin films using NMP and m‐cresol as solvents. X‐ray diffraction (XRD) reveals the presence of exceptionally highly crystalline or rather ordered regions in the PANI film samples prepared from m‐cresol. Atomic force microscopy (AFM) images also support the presence of crystalline regions on the surface of these films. The DC electrical conductivity of m‐cresol‐cast PANI is found to be quite high, and much higher than that of NMP‐cast PANI. The free‐carrier absorption tail extending to the near‐infrared region observed in the optical absorption spectrum of the m‐cresol‐cast PANI films suggests a metallic nature and regular structural arrangement in these films. Both inter‐chain and intra‐chain ordering brought about as a result of CSA doping, secondary doping effect of m‐cresol and ultrasonication are suggested to be the prime factors contributing towards the observed excellent crystallinity of these PANI films as evident from the XRD and AFM studies. The marked thermal stability of the m‐cresol‐cast PANI films is also established based on the variation of DC electrical conductivity with temperature and on thermogravimetric analysis. Copyright © 2012 Society of Chemical Industry     

Effect of low-pressure O2 and Ar plasma treatments on the wettability and morphology of biaxial-oriented polypropylene (BOPP) film

Low-pressure plasma treatments in an rf discharge of O₂ and Ar were employed to introduce polar functional groups onto the biaxial-oriented polypropylene (BOPP) surfaces to enhance the wettability and activation. The effects of plasma treatment on the morphology and wettability of the BOPP films were characterized using static contact angle measurements, attenuated total reflection (ATR)–FTIR spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM).     

Application of diamond-like carbon films to the integrated circuit fabrication process

On account of their attractive properties, amorphous diamond-like carbon (DLC) films have been developed as resist materials for lithography and as hard coatings. In this paper, we investigate the etching properties of DLC films and the electrical properties of a pn junction fabricated using DLC films.Using a parallel-plate radio frequency plasma glow discharge, methane gas was decomposed for the deposition of the DLC films on a silicon substrate. Then oxygen was used to etch the films. Properties, such as the etching rate and the cross-sectional profile, were evaluated by atomic force microscopy (AFM). In order to produce the diode, DLC films were applied to resist materials as a part of the fabrication process.The etching rate of DLC films increases with decreasing oxygen pressure. We suspect that the high etching rate at low pressure from the negative bias voltage originates from the sputtering of accelerated ionic species. The bias voltage also increases with decreasing oxygen pressure. In order to estimate the shape of the etched edge, AFM images and cross-sectional profiles of etched DLC films were investigated as a function of oxygen pressure. At high pressure, isotropic etching by neutral radicals occurred, as the shape of the etched edge was not vertical. The top and bottom edges coincided vertically at low pressure because of the high bias voltage. The yield of excellent pn junctions fabricated using DLC films as resist materials was investigated as a function of deposition and etching pressure. From the results of the characteristics of the pn junction and the yield, for the integrated circuit fabrication process the optimum condition for both deposition and etching is at low pressure.     

芳纶纳米纤维增强聚乙烯醇复合膜的制备与性能

以芳纶纤维Kevlar@49为原料,在温和条件下制备了芳纶纳米纤维分散体(ANFS),并利用分散体制备了芳纶纳米纤维/聚乙烯醇(ANFs/PVA)复合膜。通过傅里叶红外光谱(FTIR)仪、差示扫描量热(DSC)仪、原子力显微镜(AFM)、扫描电子显微镜(SEM)、电子万能试验机及透光度/雾度测定仪等考察了复合膜的微观结构、热学、光学及力学性能。FTIR证明,复合膜中ANFs与PVA具有一定的分子间氢键作用,促进了ANFs在PVA基体中的分散。由AFM和SEM可以清晰观察到直径为20~30 nm的芳纶纳米纤维分散体,并且通过SEM观察到复合膜表面较为平整。当芳纶纳米纤维质量分数为6.0%时,复合膜的抗拉强度为17.86 MPa,断裂伸长率为442%;透光度为82.63%,雾度为27.56%;玻璃化温度,熔融温度和结晶温度分别为75.20、208.82和174.51℃,表明其透光性良好,力学和热学性能达到最佳。     

Electromagnetic interference shielding of cellulose triacetate/multiwalled carbon nanotube composite films

Cellulose triacetate (CTA) and multiwalled carbon nanotube (MWNT) composite films were prepared by dispersing different weight percentages of MWNTs into a CTA solution. These composite blends were characterized by UV–vis spectroscopy (UV), and their surface mophology, thermal stability, and amended crystallinity were determined by atomic force microscopy (AFM), thermogravimetric analysis (TGA), and X‐ray diffraction (XRD), respectively. Measurements of the complex impedance of the composite samples were made in the form of films. Sheets prepared from conventional techniques were used to study microwave absorption in the microwave range of 2–12 GHz, and the effects of sample thickness on microwave absorption were investigated. The experimental results show that the electrical conductivity of composites increases with the increase in MWNT loading without a percolation threshold. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Synthesis,characterization and photovoltaic properties of a new thiophene-based double-cable polymer with pendent fullerene group

In this paper we report the synthesis of a new thiophenic 3-substituted monomer with a plastifying side chain bearing a C₆₀-fullerene moiety at the end. The monomer has been copolymerized with 3-hexylthiophene through the simplest chemical method, namely oxidative polymerization with iron trichloride. The final copolymer, with a high fullerene content (1:1 wt/wt), was fully soluble in common organic solvents and its solubility allowed for its complete physic-chemical characterization. The copolymer thermal behavior was investigated by TGA analysis showing that the incorporation of fullerene has beneficial effects on thermal stability. The fluorescence spectroscopy showed a strong quenching of fluorescence of the copolymer main chains in film, while the AFM analysis confirmed the homogeneous morphology of its films with only very small and uniformly distributed aggregates. The photovoltaic performances of the copolymer and of a film obtained by blending the prepared monomer with poly(3-hexylthiophene) were significantly higher than those obtained using conventional materials and architectures.     

Influence of high power ultrasound on physical–chemical properties of polypropylene films aimed for food packaging: barrier and contact angle features

Investigation was focused on the impact of high power ultrasound (HPUS), also called thermosonication, on the oxygen permeation properties (permeability, solubility and diffusion coefficients) of barrier films aimed for food packaging. For this purpose, biaxially oriented polypropylene (BOPP) coated with acrylic/polyvinylidene chloride (BOPPAcPVDC) and biaxially oriented coextruded polypropylene (BOPPcoex) were used. The physical–chemical profile of the samples was determined using goniometry. There is a significant impact only of extreme HPUS conditions (the longest time and the highest amplitude) on the permeability, solubility and diffusion coefficients of oxygen through the BOPP films. The highest influence on the oxygen permeability in both investigated BOPP samples involved an HPUS with an amplitude of 100% during a 6 min treatment. However, BOPP samples showed different sensitivities at lower HPUS treatments. © 2017 Society of Chemical Industry     

Efficient preparation of hybrid nanocomposite coatings based on poly(vinyl alcohol) and silane coupling agent modified TiO2 nanoparticles

In the present investigation, at first, the surface of titanium dioxide (TiO₂) nanoparticles was modified with γ-aminopropyltriethoxy silane as a coupling agent. Then a new kind of poly(vinyl alcohol)/titanium dioxide (PVA/TiO₂) nanocomposites coating with different modified TiO₂ loading were prepared under ultrasonic irradiation process. Finally, these nanocomposites coating were used for fabrication of PVA/TiO₂ films via solution casting method. The resulting nanocomposites were fully characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis/derivative thermal gravimetric (TGA/DTG), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TEM and SEM results indicated that the surface modified nanoparticles were dispersed homogeneously in PVA matrix on nanoscale and based on obtained results a possible mechanism was proposed for ultrasonic induced nanocomposite fabrication. TGA confirmed that the heat stability of the nanocomposite was improved. UV–vis spectroscopy was employed to evaluate the absorbance and transmittance behavior of the PVA/TiO₂ nanocomposite films in the wavelength range of 200–800 nm. The results showed that this type of films could be used as a coating to shield against UV light.     

Synthesis and characterization of methacrylate phospho-silicate hybrid for thin film applications

Phosphorus containing methacrylate hybrids were synthesized from 2-(methacryloyloxy)ethyl phosphate (EGMP) and 3-[(methacryloyloxy)propyl] trimethoxysilane (MEMO) via dual-cure process involving sol-gel reaction and addition polymerization. The kinetics of the reactions was established using spectroscopic techniques. Photoacoustic Fourier transform infrared spectroscopy (PA-FTIR) and X-ray photoelectron spectroscopy (XPS) confirm the formation of Si-O-Si, P-O-P and Si-O-P linkages and simultaneous polymerization of methacrylate groups leading to a dense networked structure. The presence of silicate/phospho-silicate network in the hybrid enhances its thermal stability. Nanoindentation measurements on thin films show enhanced hardness and modulus with increasing silicate network. Topographic and conductivity images obtained using micro-thermal analysis (μTA) reveal a dense, homogenous and defect-free thin film formed on metallic substrate with a T_g of 93 °C.     

Optoelectronic properties of In-doped SnS thin films

Nanostructured un- and In-doped SnS thin films were deposited on fluorine-doped tin oxide (FTO) substrates via an electrochemical deposition technique. The deposited thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), photoluminescence (PL) spectroscopy and UV–visible spectroscopy. The XRD patterns demonstrated that all deposited thin films are made of polycrystalline SnS particles. The AFM images illustrated a distinct change in the surface topography of the SnS thin films due to In-doping. The PL spectra showed two blue emission peaks and a green emission peak for all samples. Also, they highlighted a PL peak for the In-doped thin films. The incorporation of In-dopant leads to enhance in the optical absorption of SnS lattice. The optical energy band gap (E_g) of the deposited thin films was estimated using UV–vis spectroscopy, which indicated that In-doping decreases the E_g value of SnS thin films by creating defect levels. The photocurrent results demonstrated a higher photocurrent response and photocurrent amplitude for the In-doped SnS samples relative to the un-doped SnS thin film. The Mott–Schottky analysis revealed p-type conductivity for all samples. In addition, the carrier concentration of SnS was increased after In doping. The EIS spectra declared that In-doping improves the rate of charge transfer for SnS thin films. The charge transfer resistance of In-doped SnS decreased compared to the undoped SnS thin film. Finally, according to the J-V characteristics, the conversion efficiency of the In-doped SnS thin films was higher than that of the un-doped SnS sample. Therefore, the optical and electrical performance of SnS thin films were improved due to In-doping.