Preparation and characterizat ion of polypropylene/silica composite particl e with interpenetrating network via hot emulsion sol–gel approach

A novel interpenetrating structural ultrafine polypropylene-silica nanocomposite particles were synthesized by a modified sol–gel approach in the presence of the melt polypropylene emulsion. A series of samples with different polypropylene content was prepared to investigate the unique characteristics of this original nanocomposite. The thermal gravimetric analysis and differential scanning calorimetry results showed that the nanocomposites had the interpenetrating structure and good thermal stability,and the crystallization behavior of polypropylene was confined by the silica matrix. The interpenetrating structure of nanocomposites was also suggested by the nitrogen adsorption–desorption measurement results. The scanning electronic microscope and transmission electron microscopy images indicated that the nanocomposites had irregular particle morphology. The nanoparticle tracking analysis results show that the mean size of the nanocomposites was around 160 nm. According to the results obtained from different measurements,a reasonable formation mechanism was proposed.     

Preparation and characterization of poly（styrene／maleic anhydride）／kaolin nanocomposites

The direct exfoliation of in situ intercalative copolymerized styrene/maleic anhydride charge-transfer-complex (PSMA) into the inter lamellar spaces of modified kaolin (Kao-DMSO), which was intercalated and surface modified by dimethyl sulfoxide (DMSO), was reported. The nano structure of the composites was investigated by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM). The interaction between kaolin surface and PSMA chain was conformed by FTIR analysis.The XRD results showed that the intercalated polystyrene-maleic anhydride units were arranged in the flattened monolayer arrangements, and the 001 diffraction peak of the original kaolin disappeared. The TEM image showed that thekaolin was exfoliated into nanometer size and dispersed in the polymer matrix. Additionally the thermal stability of the nanocomposites was studied by thermo-gravimetric analysis(TGA), and the resulting thermogram indicated that the thermal stability of the nanocomposites was significantly increased.     

Effects of Hydrophilic Monomer Types and Level on Polystyrene-Acrylate/montmorillonite Nanocomposite Made by Emulsion Polymerization

1 Results Nanocomposite has attracted more and more interest all over the world.Polystyrene (PS) is a commercialized and mass-productive polymer,continuous research efforts have been devoted to the development of polystyrene/montmorillonite (PS/MMT) nanocomposites[1-2].But the polarity of styrene (St) is too small to intercalate the space between the clay layers.The polarity of hydrophilic monomer is so strong that it can intercalate the MMT easily,the intercalated smectic clays maybe exfoliated by using a polymer to form nanocomposites.In this work,organic modified montmorillonite (OMMT) was made by pristine montmorillonite and cetyl trimethylammonium brimide.The two kind of nanocomposite,polystyrene-acrylate/Na-MMT (PSA/MMT) and PSA/OMMT were prepared from styrene,hydrophilic acrylate monomer and MMT or OMMT by in site emulsion polymerization,respectively.Hydrophilic acrylate monomer [beta-hydroxyethyl methacrylate (HEMA),acrylic acid(AA),methyl acrylate(MA)] type,level and emulsifier type on the thermal stability of two nanocomposites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG),the structure of composites was characterized by Infrared spectroscopy (IR) analysis and X-ray diffraction (XRD).The results showed that the thermal stability of the two composites were enhanced by the addition of HEMA,AA or MAA,and PSA/OMMT nanocomposite had higher thermal stability than that PSA/MMT nanocomposite,and also HEMA had better improvement for both nanocomposites than MAA and AA.In addition,the thermal stability of the nanocomposite made by emulsifier SDS was better than that by emulsifier SDBS.Acknowledgement:Thanks to the financial support of key laboratory of new material and processing technology of Guangxi province(063006-5C-06).     

Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles

Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO₂) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO₂ nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO₂ nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO₂ films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films.     

Preparation and Structural Characterization of Polystyrene-Rectorite Nanocornposites

The polystyrene/reetorite nanocomposites were prepared by free radical polymerization of styrene containing dispersed organophilic rectorite. The structures and thermal properties of these hybrids have been investigated by X-ray diffraction (XRD), fourier transform infrared (FT-IR), positron annihilation spectroscopy (PAS) and thermal gmvimetric analysis (TGA) techniques. It was found that exfoliation of reetorite in polystyrene (PS) matrix was achieved. The average free-volume radius in the PS/clay nanocomposites is generally same as that in PS. Along with increment of reetorite contents, the interface between reetorite and polystyrene matrix increases, and the free-volume concentration decreases obviously. And the polystyrene nanocomposites have higher thermal deeomrosition temoemture than oure PS.     

Synthesis,Characterization and Water Absorption Analysis of Highly Hygroscopic Bio-based Co-polyamides 56/66

This study aims to develop highly hygroscopic bio-based co-polyamides(CPs) by melt co-polycondensation of polyamide(PA) 56 salt and PA66 salt with varying molar fractions. The functional groups and the chemical structure of the prepared samples were determined by Fourier transform infrared(FTIR) spectroscopy and proton nuclear magnetic resonance(¹H-NMR) spectroscopy. The relative viscosity was determined with an Ubbelohde viscometer. The melting behavior and the thermal stability of C...     

Enhancement of the thermo-mechanical properties and efficacy of mixing technique in the preparation of graphene/PVC nanocomposites compared to carbon nanotubes/PVC

Thin films of poly vinyl chloride(PVC)/multiwalled carbon nanotubes(MWCNT) and PVC/graphene(GN) nanocomposites were prepared by mixing in the presence of different quantities of nanoparticles. Film casting was performed using tetrahydrofuran as a solvent. The as-prepared PVC/MWCNT and PVC/GN nanocomposites were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction,thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and diffused reflectance spectroscopy. Only the PVC/GN nanocomposite films were evaluated further for detailed mechanical analysis because of the poor dispersion of MWCNTs in PVC. The PVC/GN nanocomposite films were thermo-mechanically more stable than the PVC films. These nanocomposites have potential as a replacement material for PVC and PVC/MWCNT owing to their better dispersion and high stability.     

Hyperbranched polymer-cored star polyfluorenes as blue light-emitting materials

Hyperbranched polymer-cored star polyfluorenes with high molecular weights and narrow molecular weight distribution were prepared by palladium-catalyzed one-pot Suzuki polycondensation of multi-functional cores and an AB-type monomer. The optical, electrochemical and thermal properties of the hyperbrenched polymer-cored star polymers were investigated. These polymers exhibited good thermal and color stability in solid state, and there was no significant blue-green emission after the polymers had been annealed in air for 2.5 h. Their three-dimensional hyperbranched structures could elfectively reduce the aggregation of the peripheral rigid linear conjugated polyfluorene chains.     

Preparation of Chitosan-g-PAMPS in H2O/scCO2 Inverse Emulsion

Chitosan(CS)was successfully modified in supercritical carbon dioxide(scCO2)by grafting method to enhance its water solubility.In this work,a three-arm star-like fluorinated polymer was synthesized by atom transfer radical polymerization(ATRP)method and applied as a surfactant in supercritical carbon dioxide(scCO2).Then 2-acrylamido-2-methyl propane sulfonic acid(AMPS)was grafted onto CS(CS-g-PAMPS)in H2O/scCO2inverse emulsion.The effects of mass ratio of water and surfactants(R w/s)and pressure of scCO2on the grafting reaction were investigated.The grafting rate,particle size,and dispersity in water of CS-g-PAMPS varied greatly as R w/s and pressure of scCO2changed.It could be found that the value of R w/s at 12 and the pressure of scCO2at 30 MPa were the optimum conditions for the grafting reaction.CS-g-PAMPS prepared in this reaction system has higher grafting rate,smaller particle sizes,and better dispersity in water than those prepared via conventional methods.     

Synthesis of BiOCl photocatalyst by a low-cost,simple hydrolytic technique and its excellent photocatalytic activity

A novel photocatalyst, bismuth oxychloride (BiOCl) micro-nano particles with a fine ferrite plate structure, was prepared by a low-cost, simple hydrolytic method. The as-prepared BiOCl was characterized by scanning electron microscopy (SEM), thermogravimetric analysis-differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectra (DRS). The effects of preparation conditions such as sodium dodecyl benzene sulfonate (SDBS) dispersant, HCl concentration, and heat treatment temperature on BiOCl performances were investigated. Moreover, its photocatalytic activity was evaluated on the degradation of methylene orange (MO) and was compared with that of TiO₂ (P25). The experimental results confirmed that BiOCl micro-nano particles prepared with SDBS, the HCl concentration of 1.5 mol/L, and the heat treatment temperature of 80℃ exhibited the best performance for the photodegradation of MO solution, and they showed good stability and better photocatalytic activity than P25 photocatalyst.     

A Novel Polymethyl Methacrylate （PMMA）TiO2 Nanocomposite and Its Thermal and Photic Stability

A new kind of polymethyl methacrylate （PMMA）-TiO2 nanocomposite was synthesized through polymerization. The thermal and photic stability of this PMMA TiO2 nanocomposites were investigated. The as prepared samples were characterized by scanning electron microscopy （SEM）, UV-Vis spectroscopy, differential thermal analysis （DTA） and the photo-induced weight loss, The results show that the photostability of the PMMA-TiO2 nanocomposite is higher than that of the pure PMMA under UV-light irradiation, The weight loss of the pure PMMA reaches 30 % after 300 h UVirradiation, while the composite only 0.3% under the identical experimental condition. The glass transition temperature （TR） of pure PMMA is only 80℃, while the Tg of the composite reaches 258℃. Compared with pure PMMA, the thermal stability of the composite is greatly enhanced.     

Gas-sensing properties of nanocomplex metal oxide

The development of CuOCeO2 nanocomposites as the sensing material of semiconductor gas sensors is reported. CuOCeO2 nanocomplex oxide is prepared by modified sol-gel method that uses copper nitrate, cerium nitrate and ethylene glycol as precursors. The optimized synthesis parameters and processing condition have been established. The particle size and distribution, phase morphology, specific surface, electronic states of atoms and gas sensing properties have been systematically characterized by Transmission Electron Microscope (TEM), Brunauer Emmett Teller (BET), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and gas sensitivity measurement. The results show that the sensor sensitivity depends on particle size, CuCe cation ratio and calcination temperature. The effects of calcinations temperature and CuO loading on the gas sensitivity are also examined. The optimum calcination temperature and the CuO content for the highest sensitivity are 600 ℃ and 12%, respectively. The combination of excellent thermal stability and tunable sensing properties through careful control of the processing parameters and selection of material composition gives rise to novel nanocomposites attractive to the sensitive and selective detection of a variety of toxic and combustible gases.     

Dialdehyde starch nanoparticles： Preparation and application in drub carrier

Dialdehyde starch nanoparticles (DASNP) were prepared by the redox reaction of NaIO4 and starch in water-in-oil microemulsion. IR spectrum showed that DASNP had aldehyde groups, and quantitative alkali consumption showed that its dialdehyde content was about (50±5)%. The average diameter of DASNP determined by SEM was about 100 nm. TGA-DTA showed that its thermal stability was better than starch nanoparticle (StNP) and dialdehyde starch (DAS). Its low biological toxicity was detected by cell experiment. Also the best mass ratio of doxorubicin (DOX) to combined DASNP detected by UV-VIS was 15 : 1, and the product was effective for controlled release of DOX. The cell experiment showed that the drug-carrier particle (DOX-DASNP) can release DOX for a long time and strengthened the effect of the anticancer drug. This work demonstrates that the DASNP, which has good thermal stability, small particle size, low biological toxicity, and slowly anticancer drug-releasing to strengthen drug effect, is a potentially useful carrier for anticancer drug.     

Preparation and Composition-Structure-Thermal Stability Relation of a Novel Open-framework Vanadium Phosphate (H3NCH2CH2NH3)3[(VO)4(PO4)2(HPO4)4]

A novel open-framework vanadium(Ⅳ) phosphate (H3NCH2CH2NH3)3[(VO)4(PO4)2(HPO4)4] (short for V2P3-en) has been prepared. It is synthesized hydrothermally in the presence of ethylenediamine (en) at 170℃ for 5 days by self-assembly from structurally simple precursors V2O5, H3PO4 and H2O. The compound is characterized by means of Fourier transform-infrared spectroscopy (FT-IR), Thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction analysis (XRD) and Scanning electron microscopy (SEM). Furthermore, the composition-structure-thermal stability relation of V2P3-en is explored in terms of crystal chemistry, and the potential approach to the enhancement of its thermal stability is proposed.     

Novel Fluorene-thiophene Copolymers and Polymer Blends for Photonic Devices

1 Results In this contribution we deal with photophysical and photoelectrical study of novel fluorene-thiophene copolymers, and thiophene-based oligomers and polymers, the syntheses of which are reported in our other contributions. Information about electronic structure of the polymers was obtained from cyclic voltammetry and absorption spectroscopy. The absorption of the polymers under study covers the whole visible region; the low band-gap polymer (Eg=1.35 eV) exhibited the long-wavelength absorption maximum at 785 nm with a shoulder up to 950 nm in thin layer. The ionization potential, EIP (HOMO level) in the range 4.85-5.35 eV and electron affinity, EA (LUMO level) 2.8-3.8 eV for the polymers under study were estimated; hence, polymers with donor as well with acceptor character were used. Photoluminescence, charge photogeneration and transport properties were investigated. The performance could be improved by polymer blending or doping. Photoinduced electron transfer between donor and acceptor molecules with significantly different HOMO/LUMO levels (formation of bulk heterojunction) can efficiently dissociate photogenerated excitons. Fluorescence quenching after blending or acceptor doping was demonstrated and also an increase in photostability, which was followed by absorption spectroscopy, was observed. In addition, the surface photovoltage method was utilized for photophysical study of thin films and evaluation of the thickness of the space charge region and the diffusion lengths by fitting theory to the experimental data. The results are discussed also in relation to photoluminescence study of thin films.     

Effect of Polydimethylsilxoane Molecular of Soft Segment on Novel Urethane-Siloxane Copolymers

Novel segmented urethane-siloxane copolymers were synthesized by a two-step bulk polymerization procedure using 4,4'-methylenediphenyl diisocyanate( MDI) and 1,4-butanediol( BDO)as the hard segment components and novel polypropyleneoxide polyether( PPO) blocked polydimethylsilxoane( PDMS) α,ω-dihydroxy-( PPO-PDMS-PPO) as the soft segment component,where the hard segment content was 30% by weight,and the molar ratio of NCO / OH was 1. 02. A series of urethane-siloxane copolymers were prepared from different molecular weights of α,ω-dihydroxy-( PPO-PDMS-PPO). The soft segments were different in the molecular of PDMS block segment. Chemical structure,morphology,mechanical properties,surface properties and thermal properties of thermoplastic polyurethane( TPU) were investigated by Fourier transform infrared spectroscopy( FT-IR),scanning electron microscopy and energy dispersive X-ray spectroscopy( SEM-EDX),mechanical properties( MP) test,water contact angle( WCA) test,differential scanning calorimetry( DSC),thermogravimetric analysis( TGA), respectively. According to the obtained results, the hydrophobicity of silicone modified TPU promoted,surface WCA increased from 73° to 120°. Low temperature resistant performance was improved,and the glass transition temperature decreased from- 44. 2℃ to- 120. 8℃. Thermal stability was also improved,the beginning temperature of thermal degradation increased from 281 ℃to 299 ℃.     

Flame retardancy of polyamide 6 hybrid fibers:Combined effects ofα-zirconium phosphate and ammonium sulfamate

Synergistic effect between α-zirconium phosphate(α-ZrP) and ammonium sulfamate(AS) for enhanced flame retardant properties of Polyamide 6(PA6) was investigated by using oxygen index instrument,cone calorimeter,thermogravimetric analyzer(TGA),Instron universal test machine and scanning electron microscopy(SEM).PA6/AS/α-ZrP ternary hybrid materials with various contents of α-ZrP and AS were fabricated by melt-mixing method.The result from flammabihty indicated that the Limiting oxygen index(LOI) and Underwriters Laboratories-94(UL-94) rating of PA6/AS/α-ZrP were significantly accelerated under the coordinating function of α-ZrP and AS.Moreover,the thermal stability for PA6/AS/α-ZrP studied by TGA also demonstrated this synergistic effect between α-ZrP and AS on the heat resistance.The effects of the usage amount of α-ZrP and AS on mechanical properties were analyzed by using uniaxial tensile test.It was found that the addition of AS provided negative effects on the tensile strength of PA6/AS/α-ZrP,however,the adverse trends that mentioned above could be overcome by using the well dispersed α-ZrP.     

Novel electric conductive polylactide/carbon nanotubes foams prepared by supercritical CO2

In this paper,novel electric conductive polylactide/carbon nanotubes(PLA/CNTs) foams were fabricated by a pressure-quench process using supercritical CO2as a blowing agent.The morphology of PLA/CNTs nanocomposites prepared by solution blending was characterized using SEM and the results indicate that CNTs well dispersed in PLA matrix.The introduction of CNTs improved the thermal stability of PLA.The morphology and electrical properties of PLA/CNTs foams were characterized and discussed.Depending on the process parameters,such as saturation temperature and pressure,nanocellular or microcellular structure of PLA/CNTs nanocomposites were obtained.The volume resistivity of PLA/CNTs foams was from 0.53 103Ω cm to 15.13 103Ω cm,which was affected by cell structure and crystallization of foams oppositely.Foaming reduced the electrical conductivity due to the decrease of CNTs volume content and the break of conductive pathways.However,crystallization increased the electrical conductivity possibly because of the CNTs structural change in which the CNTs were less curled and more connected.     

Synthesis and Wetting Behavior of Polyurethanes Containing Polyoxetane Soft Blocks with Semifluorinated and Bromomethyl Side Chains

Polyoxetanes bearing short fluorinated and/or bromomethyl pendant groups were prepared from 3,3-bis(2,2,2-trifluoroethoxymethyl)oxetane and/or 3,3-bisbromomethyloxetane by ring-opening polymerization.A series of novel polyurethanes(PUs)containing polyoxetanes as soft blocks was synthesized by the reaction of polyoxetanes,isophorone diisocyanate(IPDI),and 1,4-butanediol(BD).The thermal properties and wetting behavior of these novel polymers were evaluated using TGA,DSC and contact angle analysis.The cotton fabrics treated with PU3 showed good hydrophobic property,and its contact angle for water was 133°.     

Photocatalytic oxidation of gaseous benzene over nanosized TiO2 prepared by solvothermal method

Nanosized TiO2 particles were prepared by solvothermal method using tetrabutyl titanate as precursor,ethanol and water as solvents,and a facile immobilization method of nanosized TiO2 particles on woven glass fabric was developed. The samples obtained under various preparation conditions were charac-terized by means of thermo gravimetric analysis(TG) and differential scanning calorimetry(DSC) ,X-ray diffraction(XRD) ,transmission electron microscopy(TEM) ,high resolution-transmission electron mi-croscopy(HR-TEM) ,and Brunauer-Emmett-Teller(BET) . The results show that the cube-shape of TiO2 prepared by solvothermal method has good crystallinity of(101) surface,higher thermal stability and large specific surface area. Scanning electron microscopy(SEM) images confirmed that the immobi-lized TiO2 film was uniformly distributed and clung to the substrate firmly. The photocatalytic activity of the catalysts was tested using photocatalytic oxidation of gaseous benzene. The results show that the TiO2 calcined after solvothermal treatment suffers from lower specific surface area,and hence de-creases its photocatalytic activity. The photocatalytic activities of the TiO2 by solvothermal treatment with or without calcination in degradation 400 mg/m3 benzene are 3.7 and 4.1 times as high as catalyst without solvothermal treatment,respectively.