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1.
Nanocomposites of polyimides (PI) with covalently grafted polyhedral oligomeric silsesquioxane (R7R′Si8O12 or POSS) units were prepared by thermally‐initiated free‐radical graft polymerization of methacrylcyclopentyl‐POSS (MA‐POSS) with the ozone‐pretreated poly[N,N′‐(1,4‐phenylene)‐3,3′,4,4′‐benzophenonetetra‐carboxylic amic acid] (PAA), followed by thermal imidization. The chemical composition and structure of the PI with grafted methacrylcyclopentyl‐POSS side chains (PI‐g‐PMA‐POSS copolymers) were characterized by nuclear magnetic resonance (NMR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The POSS molecules in each grafted PMA side chain of the amorphous PI films retained the nanoporous crystalline structure, and formed an aggregate of crystallites. The PI‐g‐PMA‐POSS nanocomposite films had both lower and tunable dielectric constants, in comparison with that of the pristine PI films. Dielectric constants (κ's) of about 3.0–2.2 were obtained. The present approach offers a convenient way for preparing low‐κ materials based on existing PI's. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006 相似文献
2.
Muhammad Khalil Chang‐Sik Ha Shaukat Saeed Irum Majeed Khan Zahoor Ahmad 《Polymer Composites》2010,31(4):645-652
Polyimide molecular composite (MC) films were prepared by embedding a stiff‐chain polyimide (PIS) in the ductile matrix of a flexible‐chain polyimide (PIF) by blending their respective poly(amic acid) precursor solutions, followed by casting, drying, and thermal imidization upto 300°C. The PIS was prepared from pyromellitic dianhydride (PMDA) and 1,5‐diaminonaphathalene (DAN), whereas the PIF was prepared from the same dianhydride and 4,4′‐oxydianiline (ODA). Transparent, tough, and creasable MC films were obtained with 2.5–40 wt% of PIS content. The disruption of crystalline order of PIS in the MC films evidenced its fine dispersion in the matrix. Visco‐elastic measurements showed a single and enhanced value of the glass transition temperature for MC films indicating miscibility of this polyimide pair. Furthermore, the variation of charge transfer (CT) fluorescence intensity with the PIS content in the blends verified complete miscibility upto 30 wt% of PIS loading. These MCs showed a notable enhancement in the mechanical properties. Among all, the blend containing 30 wt% of stiff‐chain molecules gave the best combination of properties when compared with the matrix polyimide: a 50% higher value of tensile modulus, a 17°C rise in the glass transition temperature, and better thermal stability. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers 相似文献
3.
Haitao Yu Yajie Lei Xuejiang Yu Xianzhong Wang Tao Liu Shikai Luo 《Journal of Polymer Research》2016,23(6):121
The introduction of polyhedral oligomeric silsesquioxane (POSS) particles which act as heterogeneous nucleation agent was applied to improve the cellular morphology of nanocellular polyetherimide (PEI) foams. The loading of POSS particles increases the solubility and diffusivity characteristics of gases in nanocomposite sheets by changing the distribution of the free volume and enlarging the unoccupied volume in polymer matrix. When the range of content of POSS particles is 0.2?~?1.0 wt. %, the range of the calculated surface tension of PEI/scCO2 (γ mix ) and radius of the critical nucleus (r*) are 30.98?~?28.14 mN/m, and 6.88?~?6.25 nm, respectively. However, the small aggregated POSS particles are favour of heterogeneous nucleation bacause the actual diameter of the aggregated POSS particles is approximate to twice r*, so the addtion of 0.5 wt. % POSS to PEI matrix presents excellent heterogeneous nucleation performance for foaming. The average cell size of 0.5 wt. % POSS/PEI nanofoams compared with neat PEI decreases from 108 to 66 nm and the cell density increses from 5.96?×?1014 to 3.34?×?1015 cells/cm3. 相似文献
4.
Yongli Cui Chao Yang Zhiheng Zhuang Mingzhen Wang Quanchao Zhuang 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(3):731-737
In this study, spheroid LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode material were synthesized using LiOH with Ni0.5Co0.2Mn0.3(OH)2 precursor by a simple solid-state reaction, and characterized by X-ray diffraction and scanning electron microscopy. Electrochemical behavior of NCM111 was investigated by electrochemical impedance spectroscopy (EIS) combining with cyclic voltammogram (CV) and charge/discharge test in the 1 M LiPF6-EC:EMC electrolyte with ethylene sulfate (DTD) and methylene methanedisulfonate (MMDS) additives either singly or in combination with high cutoff voltage of 3.0–4.5 V at room temperature of 25 °C or elevated temperature of 55 °C. It was found that DTD additive can increase the initial coulombic efficiency of NCM111, and the spheroid NCM111 can obtain the maximum initial discharge capacity of 177.81 mAh/g with the 2 wt% DTD, and keep 92.29% capacity retention after 80 cycles. The MMDS additives would decrease the initial discharge capacity of the NCM111, and enhance significantly long cycle life of the NCM111 with the capacity retention of 99.23% over 80 cycles at high voltage of 4.5 V. The additive combination 2 wt% DTD?+?1 wt% MMDS was an optimal additive combination, demonstrating the 102.2% capacity retention over 80 cycles at room temperature and the 94.2% capacity retention over 70 cycles at elevated temperature of 55 °C. EIS results revealed that the additive blend of 2 wt% DTD?+?1 wt% MMDS can drastically lower the kinetics impedance and suppress the growth rate of R ct for the NCM111 electrode. 相似文献
5.
Plasticized solid polymer electrolytes (PSPEs) consisting of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50/50 wt%) based matrix with lithium tetrafluoroborate (LiBF4) as dopant ionic salt (10 wt%) and varied concentrations (x = 0, 5, 10 and 15 wt%) of ethylene carbonate (EC) as plasticizer have been prepared. Classical solution-cast (SC) and the ultrasonic assisted followed by microwave irradiated (US–MW) solution-cast methods have been used for the preparation of (PEO–PMMA)–LiBF4–x wt% EC films, and the same have been hot–pressed to get their smooth surfaces. Dielectric relaxation spectroscopy (DRS) and X–ray diffraction (XRD) techniques have been employed to characterize the dielectric and electrical dispersions and the structural properties of the PSPE films, respectively. It has been observed that the ionic conductivity of these semicrystalline ion-dipolar complexes is governed by their dielectric permittivity and polymers chain segmental dynamics. The increase in ionic conductivity values with the increase of plasticizer concentration in the PSPEs also varies with the films’ preparation methods. The US–MW method prepared PSPE film containing 15 wt% EC has a maximum ionic conductivity (1.86 × 10?5 S cm?1) at room temperature, whereas, the films having low concentrations of EC exhibit the conductivity of the order of 10?6 S cm?1. 相似文献
6.
Polyhedral oligomeric silsesquioxane (POSS) and glycidyl methacrylate (GMA) are used to synthesize linear L-(PGMA-b-MA-POSS), dicephalous D-(PGMA-b-MA-POSS)2, and four-armed T-(PGMA-b-MA-POSS)4 through atom transfer radical polymerization (ATRP). These different structured POSS/GMA-containing copolymers are applied to build the porous films through breath-figures (BF) method. L-(PGMA-b-MA-POSS) is easy to form the ordered porous BF film, and T-(PGMA-b-MA-POSS)4 tends to form well-distributed BF film due to its high segment density which is beneficial to stabilize water drop. It is proven that solvent has a great effect on the morphologies of BF film. The perfect BF film is developed in the relatively wet atmosphere as 5–8 μm diameter of pores casted in THF and 2–4 μm diameter of pores casted in CH2Cl2 with regular morphology. The developed BF film has superior stability than the film developed in natural conditions due to the shorter stable balancing time. Therefore, it is believed that the obtained porous films show great potential in coating application. 相似文献
7.
Shobhna Choudhary 《Journal of Polymer Research》2018,25(5):116
The polymer nanocomposite (PNC) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrices dispersed with nanoparticles of amorphous silica (SiO2) have been prepared by solution-cast method followed by melt-press technique. Effects of SiO2 concentration (x?=?0, 1, 3 and 5 wt%) and PEO–PMMA blend compositional ratios (PEO:PMMA?=?75:25, 50:50, and 25:75 wt%) on the surface morphology, crystalline phase, polymer-polymer and polymer-nanoparticle interactions, melting phase transition temperature, dielectric permittivity, electrical conductivity, electric modulus and the impedance properties of the PNC films have been investigated. The crystalline phase of the PNC films decreases with the increase of PMMA contents which also vary anomalously with the increase of SiO2 concentration in the films. The melting phase transition temperature and polymer-nanoparticle interactions significantly change with the variation in the compositional ratio of the blend polymers in the PNC films. It is observed that the effect of SiO2 on the dielectric and electrical properties of these PNCs vary greatly with change in the compositional ratio of PEO and PMMA in the blends. The dielectric relaxation process of these films confirm that the polymers cooperative chain segmental dynamics becomes significantly slow when merely 1 wt% SiO2 nanoparticles are dispersed in the polymer blend matrix. 相似文献
8.
P. A. Nunes P. Pires-Cabral M. Guillén F. Valero D. Luna S. Ferreira-Dias 《Journal of the American Oil Chemists' Society》2011,88(4):473-480
This work aims to produce triacylglycerols (TAG) containing a medium-chain fatty acid (M) at positions sn-1,3 and a long-chain fatty acid (L) at sn-2 position, i.e. TAG of MLM type, by acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, catalyzed by 1,3-selective Rhizopus oryzae heterologous lipase (rROL) immobilized in Eupergit® C and modified sepiolite. This lipase was produced by the methylotrophic yeast Pichia pastoris. Reactions were performed at 25 and 40 °C, for 24 h, either in solvent-free or in n-hexane media, at a molar ratio 1:2 (olive oil:free fatty acid). Higher incorporations of C8:0 (21.6 mol%) and C10:0 (34.8 mol%) into the TAG were attained in solvent-free media, at 40 °C, when rROL immobilized in Eupergit® C was used. In organic media, at 40 °C, only 15.9 and 14.1 mol%, incorporation of C8:0 or C10:0 were, respectively observed. Lower incorporations were attained for both acids (3.4–7.0 mol%) when native ROL (nROL) in both supports and rROL in modified sepiolite were used. rROL in Eupergit® C maintained its activity during the first four or three 23-h batches, respectively when C8:0 (half-life time, t 1/2 = 159 h) or C10:0 (t 1/2 = 136 h) were used, decreasing thereafter following a time delay model. 相似文献
9.
Dachao Yuan Shuang Guo Shuaihang Hou Yuejin Ma Jianglong Wang Shufang Wang 《Nanoscale research letters》2018,13(1):382
We reported the epitaxial growth of c-axis-oriented Bi1?xBaxCuSeO (0?≤ x ≤?10%) thin films and investigated the effect of Ba doping on the structure, valence state of elements, and thermoelectric properties of the films. X-ray photoelectron spectroscopy analysis reveal that Bi3+ is partially reduced to the lower valence state after Ba doping, while Cu and Se ions still exist as +?1 and ??2 valence state, respectively. As the Ba doping content increases, both resistivity and Seebeck coefficient decrease because of the increased hole carrier concentration. A large power factor, as high as 1.24 mWm?1 K?2 at 673 K, has been achieved in the 7.5% Ba-doped BiCuSeO thin film, which is 1.5 times higher than those reported for the corresponding bulk samples. Considering that the nanoscale-thick Ba-doped films should have a very low thermal conductivity, high ZT can be expected in the films. 相似文献
10.
Polyimide/titania (PI/TiO2) nanocomposite films have been successfully fabricated through the in situ formation of TiO2 within a PI matrix via sol–gel method. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized by mixing pyromellitic dianhydride (PMDA), with equimolar amount of a diamine monomer having a pendent benzoxazole unit and two flexible ether linkages in N,N-dimethylformamide (DMF) solvent. Tetraethyl orthotitanate [Ti(OEt)4] and acetylacetone were then added to the resulted PAA. After imidization at high temperature, PI/TiO2 hybrid films were formed. The structure and morphology of the hybrid nanocomposites with different titania contents (0 wt%, 5 wt%, 10 wt%, and 15 wt%) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The results indicate that the TiO2 nanoparticles were homogeneously dispersed in the hybrid films. The thermogravimetric analysis of nanocomposites confirms the improvement in the thermal stability with the increase in the percentage of titania nanoparticle. Transmission electron microscopy showed that the nanoparticles with an average diameter of 25–40 nm were dispersed in the polymer matrix. 相似文献
11.
Congyan Li Lang Yi Shuting Xu Xiuming Wu Wei Huang Deyue Yan 《Journal of Polymer Research》2017,24(1):7
A novel diamine 4,4′-(3-(tert-butyl)-4-aminophenoxy)diphenyl ether (4) was synthesized from 2-tert-butylaniline and 4,4′-oxydiphenol through iodination, acetyl protection, coupling reaction and deacetylation protection. Then some polyimides (PIs) were obtained by one-pot polycondensation of diamne 4 with several commercial aromatic dianhydrides respectively. They all exhibit enhanced solubility in organic solvents (such as NMP, DMF, THF and CHCl3 etc.) at room temperature. Their number-average molecular weights are in the range of (2.1–3.7)?×?104 g/mol with PDI from 2.25 to 2.74 by GPC. They can form transparent, tough and flexible films by solution-casting. The light transparency of them is higher than 90% in the visible light range from 400 nm to 760 nm and the cut-off wavelengths of UV–vis absorption are below 370 nm. They also display the outstanding thermal stability with the 5% weight loss temperature from 525 °C to 529 °C in nitrogen atmosphere. The glass transition temperatures (T g s) are higher than 264 °C by DSC. XRD results demonstrate that these PIs are amorphous polymers with the lower water absorption (<0.66%). In summary, the incorporation of tert-butyl groups and multiple phenoxy units into the rigid PI backbones can endow them excellent solubility and transparency with relatively high T g s. 相似文献
12.
Cathren E. Gowenlock Virginia Gomez James D. McGettrick Enrico Andreoli Andrew R. Barron 《Journal of Coatings Technology and Research》2017,14(1):195-205
Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu0 but with surface oxidation, and show a faceted morphology, which is more textured (R q = 460 ± 90 nm) compared to the SAM (R q = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl2/PdCl2 catalyzed electroless deposition, using formaldehyde (CH2O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu2+ to the iNA is proposed to facilitate reduction to Cu0 and create the seed for subsequent growth. The films show good adhesion to the functionalized surface. 相似文献
13.
Sepideh Bahrami Maryam Mizani Masoud Honarvar Mohammad Abdollahian Noghabi 《Iranian Polymer Journal》2017,26(11):885-893
Latent heat storage system by phase change materials is an effective method to achieve high density energy storage. A novel composite pellet consisted of a blend of linear low density polyethylene and low density polyethylene (LLDPE/LDPE) with low molecular weight paraffin (a phase change material, at 25 and 50 wt%) has been developed and coated by calcium silicate to prevent paraffin leakage. Three-layer coextruded films containing the paraffin composites as the middle layer have been prepared from each group for application as plastic film cover to control undesirable temperature variations during the storage of agricultural crops. The Melt Flow Index and thermal properties of the pellets as well as the quantity of paraffin leakage were studied. Thermal/morphological and permeation properties of the coextruded films have been investigated. The results showed that the LLDPE/LDPE polymer matrix provided an appropriate structural morphology for low molecular weight paraffin (n < 18) entrapment with good miscibility and low paraffin leakage (< 5%). Based on differential scanning calorimetry (DSC) thermographs, this type of paraffin may promote the compatibility between linear and low-density polyethylene. A dispersion-type morphology was observed in the micrograph of LLDPE/LDPE film, where the sizes of the spherical micro-domains were reduced as evident in the microscopic images of the paraffin-containing composite films. At storage temperatures below the phase change temperature (T < 25 °C), the oxygen permeability was substantially decreased because of the combined effects of paraffin crystallites and calcium silicate. 相似文献
14.
Víctor M. Ovando-Medina Nancy E. Dávila-Guzmán Nancy V. Pérez-Aguilar Hugo Martínez-Gutiérrez Iveth D. Antonio-Carmona Silvia Y. Martínez-Amador Andrés Dector 《Iranian Polymer Journal》2018,27(3):171-181
A composite based on coffee grounds waste (CGW) coated with the semi-conducting polypyrrole (PPy) was prepared by pyrrole polymerization using potassium persulfate as oxidant. The composite was characterized by FTIR spectroscopy, cyclic voltammetry, UV/vis spectroscopy, scanning electron microscopy (SEM) and TGA analysis. SEM analysis showed homogeneous coating of coffee fibers with spherical nanoparticles of PPy with diameters in the range of 200–300 nm. Aqueous adsorption experiments of rhodamine B dye (RhB) onto the as-prepared composite were performed. The effect of pH and initial dye concentration (C0) on the adsorption behavior was studied. The results showed that this material was an efficient adsorbent of RhB dye at alkaline pH. The adsorption experiments were set at C0 = 200 mg/L and initial pH values of 2.0, 3.25 and 9.0, the adsorption capacities were 7.22, 13.8, and 19.0 mg of dye/g of the composite, respectively. Nonetheless, when pH was maintained at 9.0 throughout adsorption time, the adsorption capacity increased to 32 mg of dye/g of the composite. When performing adsorption tests using pure CGW, dye adsorption was insignificant at any pH level. Adsorption isotherm for RhB at controlled pH of 9.0 was well described by the Redlich–Peterson model and by the typical Langmuir adsorption model with a theoretical maximum adsorption capacity (qmax) of 50.59 mg of dye/g of composite. 相似文献
15.
Fahd Jamshaid Adnan Ahmad Muhammad Adrees Sadia Sagar Iqbal Hira Zaheer Tahir Jamil Javaid Ahmad Tousif Hussain 《Iranian Polymer Journal》2017,26(12):913-927
The incorporation of functionalized nanoscale fillers into traditional glass fiber/unsaturated polyester (GF/UPE) composites provides a more robust mechanical attributes. The current study demonstrates the potential of 3-mercaptopropyl trimethoxysilane (MPTS)-functionalized carbon black (f-CB) for enhancing the thermo-mechanical properties of GF composites. The composites infused with 1, 3 and 5 wt% of pristine and MPTS-functionalized CB were fabricated by hand lay-up and hot press processing. Tensile testing, interlaminar shear strength (ILSS) testing and dynamic mechanical analysis were used to evaluate the performance of nanocomposites. Fourier transform infrared spectroscopy validated the MPTS functionalization of CB. Pristine CB-loaded nanocomposites exhibited marginal improvement in ultimate tensile strength (UTS), ILSS and thermo-mechanical properties. However, with the addition of f-CB, the improvement in all the studied properties was more substantial. The inclusion of 5 wt% f-CB increased the elastic modulus and UTS by 16 and 22%, respectively, whereas the ILSS was enhanced by 36%, in comparison to the neat GF composite. The scanning electron microscope analysis of fractured ILSS samples revealed better fiber-matrix adhesion and compatibility in f-CB-loaded nanocomposites. At the same filler weight percentage, the storage modulus at 25 °C was ~ 19% higher than that of neat composite. The f-CB inclusion resulted in increment of T g by ~ 13 °C over the T g of neat GF/UPE composite (~ 109 °C). These improvements were due to the chemical connection of f-CB to the UPE matrix and GF surface. With such improvements in thermal and mechanical properties, these nanocomposites can replace the conventional GF composites with prominent improvements in performance. 相似文献
16.
Changwoon Nah Sang Hyub Han Joong‐Hee Lee Myong‐Hoon Lee Kyung Ho Chung 《Polymer International》2004,53(7):891-897
Montmorillonite (MMT)‐based polyimide (PI) nanocomposites were prepared via two‐stage polymerization of PI using polyamic acid (PAA). The clay was organically modified using various alkylammonium ions to examine the effect of changes in alkyl length on the intercalation spacing of both the treated clays and their hybrids with PAA and PI. The intercalation behavior of clay in the PI matrix and its thermal and mechanical properties were investigated as a function of clay concentration. The d‐spacing of organically modified MMT (O‐MMT) increased with increasing length of the alkylammonium chain. PI/O‐MMT hybrids form exfoliated nanocomposites at clay concentrations below 2 wt%, while they form intercalated nanocomposites together with some exfoliated ones at clay contents exceeding 4 wt%. Young's modulus increased rapidly to a clay loading of 2 wt%, and leveled off with further increases in clay loading. The tensile strength at break increased rapidly up to a clay loading of 1 wt%, and then decreased sharply, while the strain at break showed a monotonic decrease with increasing clay loading from 0 to 8 wt%. The storage modulus, E′, in the temperature range below the glass transition temperature Tg, generally increased with increasing clay content, except at the highest clay content of 8 wt%. Copyright © 2004 Society of Chemical Industry 相似文献
17.
The spun tapes of synthesized PAN, its copolymer with 1 wt% itaconic acid, and doped version with 1 wt% sodium dodecyl sulfate (SDS) all showed stripy, even, and compact cross-sections as the hallmark of gel forming products. PAN doping with SDS and acrylonitrile copolymerization with itaconic acid reduced its dimethylformamide (DMF) solution structural viscosity index (Δη) by 50% and 30%, respectively, at 675 s??1. In addition, the modification of synthesized PAN through doping and acrylonitrile copolymerization with itaconic acid led to severe and mild gelation temperature decrease, respectively. The stabilization peak of the synthesized PAN tape was enhanced as much as 25 °C by 900% hot drawing, decreased by about 10 °C through copolymerization, while experienced small temperature changes through doping. The second derivative of Fourier transform infrared and Gaussian fitting was used to analyze the tapes cyclization due to stabilization treatment through introducing Isd index. 10 min Isd index was raised as much as 430% and 800% in comparison with the synthesized PAN through its doping or acrylonitrile copolymerization with itaconic acid, respectively. Further 180 min of Isd index, however, showed the same proportional increase as toughness of the drawn tapes versus their heat of stabilization through their physical and chemical modifications. 相似文献
18.
Linshuang Li Jianfei Che Liu Xiaohong Wei Zhao Zhifeng Ye 《Polymer-Plastics Technology and Engineering》2019,58(2):172-181
A series of white fluorinated polyimide/TiO2 composite films were prepared by a solution mixing method. They showed high tensile strength beyond 95.1MPa and excellent insulting property with surface and volume resistances exceeding 1.9 × 1011Ω and 2.3 × 1012 Ω cm, respectively, coupled with water absorptions below 1.1%, water contact angles up to 95.9 and whiteness beyond 58.5. It was found that their optical transparency decreased dramatically with the increasing doping of TiO2. The thermal degradation of pure fluorinated polyimide (FPI) and representative polyimide/TiO2 composite film with 5 wt% of TiO2 (PI/TiO2-5 wt%) was also studied. 相似文献
19.
Recently, the preparation of nanodiamond–polymer composites has attracted the attention of materials scientists due to the unique properties of nanodiamonds. In this study, novel polyimide (PI)/phosphorylated nanodiamonds (PNDs) composites were prepared. PNDs were achieved from the reaction of methylphosphonic dichloride with nanodiamonds in dichloromethane. Precursor of polyimide, which is the poly(amic acid) (PAA), was successfully synthesized with 3,3′, 4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐oxydianiline in the solution of N,N‐dimethylformamide. Different ratios of phosphorylated nanodiamond particles were added into PAA solution and four different nanocomposite films were prepared. The amount of PNDs in the composite films was varied from 0 wt% to 3 wt%. The structure, thermal and surface properties of polyimide films were characterized by scanning electron microscopy (SEM), ATR‐FTIR, thermogravimetric analysis (TGA), ultraviolet visible spectroscopy, and contact angle. SEM and FTIR results showed that the phosphorylated nanodiamond and PI/PNDs films were successfully prepared. Phosphorylated nanodiamonds were homogeneously dispersed in the polymer matrix and they displayed good compatibility. TGA results showed that the thermo‐oxidative stability of PI/PNDs films was increased with the increasing amount of phosphorylated nanodiamond. POLYM. COMPOS., 37:2285–2292, 2016. © 2015 Society of Plastics Engineers 相似文献
20.
Hengameh Honarkar Mohammad Barmar Mehdi Barikani Parvin Shokrollahi 《Korean Journal of Chemical Engineering》2016,33(1):319-329
A series of aqueous polyurethane nanocomposites were prepared using various amounts (0.3-4.6 wt%) of a diol functionalized polyhedral oligomeric silsesquioxane (POSS) by the prepolymer mixing method. N,N-bis(2-hydroxy ethyl-2-amino ethane sulfonic acid sodium salt (BES sodium salt) was used as the anionic internal emulsifier and ionic center. The molecular structure of the samples was characterized by ATR-FTIR spectroscopy. We investigated the effect of the POSS contents on the properties of the specimens by particle size and viscosity measurements, X-ray diffractometry, mechanical behavior assessment, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis and morphological studies. The results showed that with increasing the POSS contents, particle size, viscosity, tensile strength, modulus, T g , and thermal stability of the synthesized samples were improved. Also, SEM and TEM images indicated that a homogeneous morphology was obtained in the 1.2 wt% POSS-based sample. AFM results showed that the surface roughness increased as the POSS amounts increased. 相似文献