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1.
A soapless emulsion polymerization method was applied to synthesize CaCO 3/PMMA spherical composite with different loading of CaCO 3. CaCO 3 nanoparticles were pretreated with oleic acid after the carbonation process of Ca(OH) 2 slurry by CO 2, in order to improve the compatibility between the CaCO 3 particles and MMA monomer in emulsion system. The results of photon correlation spectroscopy (PCS) showed the particles size of composites were bigger than the pure PMMA. And the size increased with the increase of the content of CaCO 3 nanoparticles. TEM images showed that the morphology of the composite microspheres was uniform and CaCO 3 nanoparticles can be well encapsulated in the polymeric microsphere, and were located at the edge of the spheres. The results of DTG and TG indicated that the CaCO 3 nanoparticles could improve the thermal stability of PMMA. Moreover, capsulation of CaCO 3 by PMMA can increase the acid-resistant of CaCO 3 nanofillers. 相似文献
2.
The influences of nanosized CaCO 3 on the thermal and optical properties embedded in poly(methyl methacrylate) (PMMA) and polystyrene (PS) were investigated.
Calcium carbonate nanoparticles were synthesized by in situ deposition technique, and its nano size (32–35 nm) was confirmed
by scanning electron microscope (SEM) and X-ray studies. Nanocomposites samples of PMMA/CaCO 3 and PS/CaCO 3 were prepared with different filler loading (0–4 wt%) of CaCO 3 nanoparticles by solution mixing technique. The Fourier transform infrared analysis confirmed that CaCO 3 nanoparticles were present in the polymers matrices. The morphology and elemental composition of nanocomposites were evaluated
by SEM and energy dispersive X-ray spectroscopy. The thermal properties of nanocomposites were characterized by differential
scanning calorimetric, thermogravimetric, and differential thermogravimetry analysis, and the results indicate that the incorporation
of CaCO 3 nanoparticles could significantly improve the thermal properties of PMMA/CaCO 3 and PS/CaCO 3 nanocomposites. The glass transition temperature ( T
g
) and decomposition temperature ( T
d
) of nanocomposites with 4 wt% of CaCO 3 nanoparticles were increased by 30 and 24 K in case of PMMA/CaCO 3 and 32 and 15 K in the case of PS/CaCO 3 nanocomposites, respectively. The obtained transparent nanocomposites films were characterized using UV–Vis spectrophotometer
which shows the transparencies of nanocomposites are almost maintained in visible region while the intensity of absorption
band in ultraviolet (UV) region is increased with CaCO 3 nanoparticles contents and these composites particles could enhance the UV-shielding properties of polymers. 相似文献
3.
Summary: We previously discovered that structurally well-defined polymer/inorganic composite particles, i.e., poly(methyl methacrylate) (PMMA)/CaCO 3/SiO 2 three-component composite particles, can be achieved via reverse atom transfer radical polymerization (ATRP), using 2,2′-azo-bis-isobutyronitrile as initiator and Cu II bromide as catalyst. In the present study, the influence of the mass ratio of CaCO 3/SiO 2 two-component composite particles to methyl methacrylate (MMA) on the rate and behavior of the polymerization was studied in detail. The results illustrate that increasing the mass ratio of CaCO 3/SiO 2 two-component composite particles will decrease the overall rate of polymerization of MMA under standard reverse ATRP conditions. Thermal properties of the obtained well-defined particles were characterized and determined by thermogravimetric analysis (TGA). The results indicate that well-defined PMMA chains grafted on the surface of CaCO 3/SiO 2 particles were only degraded by random chain scission of C C linkages within the PMMA chain, which is different from the degradation of PMMA chains prepared via traditional radical polymerization. This difference is reasonably ascribed to the difference between the end groups of PMMA prepared via reverse ATRP and that via traditional radical polymerization, which has been confirmed by end group analysis measured by 1H–NMR spectroscopy. 相似文献
4.
采用铝锆偶联剂和棕榈酸改性纳米CaCO 3 粉体. 借助 XRD, FTIR, 接触角及流变学等测试方法对纳米CaCO 3 的表面结构进行表征. XRD 分析表明: 改性纳米 CaCO 3保持原样品完整的体相结构, 为方解石型纳米微晶. FTIR 分析证明: 表面改性剂与纳米 CaCO 3 表面是以化学键合和物理吸附方式相结合, 粒子表面存在羧基等有机官能团的红外吸收特征. 通过测定苯和水在改性纳米CaCO 3粉末压片上的接触角, 计算了改性纳米 CaCO 3的表面能和极性分量, 并与未改性纳米CaCO 3 进行比较. 结果表明, 经表面改性, 纳米 CaCO 3 的表面能和极性分量明显降低, 其在有机溶液中的吸附功增大, 界面张力大大降低; 经棕榈酸改性的纳米 CaCO 3 表现出较好的亲油疏水性, 而铝锆偶联剂改性的纳米 CaCO 3 同时具有亲水性和亲油性. 以液体石蜡为溶剂, 研究了表面改性对纳米CaCO 3悬浮液流变行为的影响. 实验发现: 经过表面处理, 纳米 CaCO 3 粉体悬浮液流变行为发生较大的变化, 稳态剪切黏度大大降低, 表现出较小的动态弹性储能模量和黏性损耗模量, 而损耗因子较大. 相似文献
5.
The attempt to prepare structurally well-defined polymer/inorganic composite particles, i.e., poly(methyl methacrylate) (PMMA)/CaCO 3/SiO 2 three-component composite particles, via reverse atom transfer radical polymerization (ATRP), using 2-2′-azo- bis-isobutyronitrile as initiator and Cu(II) bromide as catalyst was reported. CaCO 3/SiO 2 two-component composite particles were first obtained through sol–gel method, and their morphology and surface element information were determined by transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. The results indicate that the CaCO 3 was encapsulated by the obtained SiO 2. After being modified by silane coupling agent, the CaCO 3/SiO 2 composite particles copolymerized with methyl methacrylate (MMA) under standard reverse ATRP conditions to produce PMMA/CaCO 3/SiO 2 three-component composite particles. In the case concerned, first-order kinetic plots and linear increase of molecular weight (Mn) vs conversion and narrow molecular weight distribution for the graft polymer samples were observed. Furthermore, the gel permeation chromatography results illustrated that both the free PMMA chains from the solvent and the graft PMMA chains from the surface of CaCO 3/SiO 2 two-component composite particles were growing at the same rate. Characterizations of the PMMA-grafted CaCO 3/SiO 2 composite particles were done by Fourier transform infrared and thermogravimetric analysis. The results showed that the surface of the modified inorganic particles was grafted by the MMA and that the grafting percentage was about 8.7%. 相似文献
6.
The mechanical and morphological characteristics of PA6/ABS (60/40)-based hybrid composite containing HNO 3-treated short carbon fibers (HSCF) and CaCO 3 nanoparticles have been experimentally studied. A counter-rotating twin-screw extruder and an injection molding machine were employed to produce different samples containing 10 wt % of HSCF and 0, 2, 5 and 8 wt % of CaCO 3 nanoparticles. The SEM observations indicated high-quality adhesion between HNO 3-surface treated carbon fibers and PA6/ABS polymer matrix. In addition, the morphological studies showed that the inclusion of CaCO 3 nanoparticles caused a significant effect on the ABS particle dispersion in PA6/ABS matrix. The mechanical properties assessments revealed that the incorporation of 10 wt % HSCF into the PA6/ABS can significantly improve tensile strength (82%), tensile modulus (107%), flexural strength (98%), flexural modulus (104%) and impact resistance (24%). The inclusion of CaCO 3 nanoparticles, in the presence of 10 wt % HSCF, led to the noticeable improvements of tensile strength (128% for 2 wt % CaCO 3), tensile modulus (199% for 5 wt % CaCO 3), flexural strength (146% for 5 wt % CaCO 3), flexural modulus (204% for 5 wt % CaCO 3) and impact resistance (46% for 2 wt % CaCO 3). The surface treatment of carbon fibers, dispersion conditions of nanoparticles and ABS phase in polymeric matrix were found to be the major important factors affecting the mechanical properties. 相似文献
7.
The effect of polymethyl methacrylate (PMMA)-encapsulated calcium carbonate on the kinetics of the vulcanization of natural rubber (NR) with a vulcanizing agent (sulfur) accelerated by N-oxydiethyl benzthiazyl sulfenamide (BSM) has been studied. The PMMA coating (4% by weight of CaCO 3) was prepared by dispersion polymerization, and compositions of five NR composites were 10, 15, 20 phr of treated CaCO 3 and 20 and 40 phr of untreated CaCO 3. The vulcanization kinetics was determined by oscillating disc rheometry (ODR) and the kinetic parameters were determined by the model equations. The kinetic analysis suggests that the two-parameter auto catalytic model is the more appropriate one to elucidate the kinetics of the vulcanizing reaction of the present system. These parameters support the nature of the experimental ODR curves (degree of conversion–time plots). The encapsulated CaCO 3 leads to a change in vulcanization reaction and has an effect on the kinetic parameters E, ln K 0, m and n, and consequently on the overall reactivity. 相似文献
8.
利用铝锆偶联剂对纳米CaCO 3进行表面改性。采用红外光谱(IR)、X射线衍射分析(XRD)、热分析(TG-DTG)对改性前后的纳米CaCO 3进行了表征。通过透射电镜(TEM)、粒度分析、吸油值、比表面积及静滴接触角等实验对纳米CaCO 3的表面改性效果进行评价。红外光谱分析表明,偶联剂以化学键合的方式在纳米CaCO 3的表面形成化学吸附。TEM及粒度分析结果显示,未改性纳米CaCO 3存在严重的团聚现象,而改性后纳米CaCO 3的分散性有很大改善。经表面改性,水滴在纳米CaCO 3粉体压片表面静滴接触角变大,改性纳米CaCO 3同时具有亲水性和亲油性,能够较好地分散在水和有机相中。将改性前后的纳米CaCO 3分别加入到纸张涂料体系中,制得纳米CaCO 3复合纸张涂料。涂料流变实验表明,经铝锆偶联剂表面改性的纳米CaCO 3制得的复合纸张涂料具有较高的动态弹性模量和粘性模量。 相似文献
9.
The effect of migration of calcium carbonate (CaCO 3) nanoparticles on the breakup dynamics of Ethylene-Propylene-Diene Monomer (EPDM) droplets in Polypropylene (PP) matrix during melt extrusion was investigated in situ. The breakup process of EPDM droplets was sped up dramatically when the migration of CaCO 3 nano-particles from dispersed phase to matrix was introduced to PP/EPDM melts. It was found that both the total breakup time and the shape stability of slender EPDM droplets decreased with the increase of CaCO 3 concentration. Both the maximum value in equivalent diameter d and aspect ratio AR of EPDM droplets were also reduced by increasing the composition of CaCO 3 nanoparticles. Results were discussed in consideration of interfacial tension and migration of CaCO 3 nanoparticles. Reduction in interfacial tension is mainly responsible for the improved breakup process in the two-step composites with CaCO 3 nanoparticles (<2 wt%). Higher composition of CaCO 3 (≥2 wt%) induced the CaCO 3 aggregates in the EPDM phase. These aggregates acted as stress concentration when the EPDM droplets break up. 相似文献
10.
A new type of Cu II ion sorbents is presented. These are obtained by CaCO 3 mineralization from supersaturated solutions on gel‐like cross‐linked polymeric beads as insoluble templates. A divinylbenzene–ethylacrylate–acrylonitrile cross‐linked copolymer functionalized with weakly acidic, basic, or amphoteric functional groups has been used, as well as different initial inorganic concentrations and addition procedures for CaCO 3 crystal growth. The morphology of the new composites was investigated by SEM and compared to that of the unmodified beads, and the polymorph content was established by X‐ray diffraction. The beads, before and after CaCO 3 mineralization, were tested as sorbents for Cu II ions. The newly formed patterns on the bead surface after Cu II sorption were observed by SEM, and the elemental distribution on the composites and the chemical structure of crystals after interaction with Cu II were investigated by EDAX elemental mapping and by FTIR‐ATR spectroscopy, respectively. The sorption capacity increased significantly after CaCO 3 crystals growth on the weak anionic bead surface (up to 1041.5 mg Cu II/g sample) compared to that of unmodified beads (491.5 mg Cu II/g sample). 相似文献
11.
Silica (SiO 2) nanoparticles and silica/calcium carbonate (SiO 2/CaCO 3) core–shell nanocomposites were prepared by sol–gel technique as fillers for papermaking application. Semi-burned rice straw ash (SBRSA), as waste material, was used to prepare the targeted fillers. Preparation of SiO 2 nanoparticles and SiO 2/CaCO 3 nanocomposites was carried out using Na 2SiO 3 solution that was prepared from SBRSA and CaCO 3 nanoparticles of 30–70 nm. The targeted SiO 2/CaCO 3 nanocomposites were prepared with different molar ratio of SiO 2:CaCO 3 1:15, 1:10 and 1:5. The percentage of silica increased from 62.5% to 82.9% by thermal treatment of SBRSA at 800 °C for 2 h. The prepared SiO 2 nanoparticles and SiO 2/CaCO 3 nanocomposites were characterized by using XRD, XRF, TEM, FT-IR and Zeta potential. The results indicate that a pure semi-crystalline SiO 2 nanoparticle and semi-crystalline shell of SiO 2 coated CaCO 3 core particles were produced. The work extended also to investigate the effect of the prepared fillers on physical, mechanical and optical properties of paper.Application of the prepared SiO 2 nanoparticles and SiO 2/CaCO 3 nanocomposites improved the optical properties of paper (brightness, whiteness and opacity) but it slightly reduced the mechanical properties when compared to commercial precipitated CaCO 3 (PCC) filler.The results showed that the retention of SiO 2 nano-particles was highly increased. The retention of the prepared nanocomposites increased along with increasing of SiO 2:CaCO 3 molar ratio. 相似文献
12.
CaCO 3/polystyrene inorganic/organic composite nanoparticles (50 nm) with a core/shell structure were synthesized in 80% yield by emulsion polymerization. Nanometer CaCO 3 was pretreated with γ‐methacryloxypropyltrimethoxysilane in order to introduce polymerizable groups onto its surface. Soxhlet extraction experiments have shown that only 4% of total encapsulating polystyrene (PS) was removable when the ratio of CaCO 3 to styrene was relatively low (14.8–29.6%), indicating strong adhesion between CaCO 3 and PS. 相似文献
13.
Oil refinery is one of the fast growing industries across the globe and it is expected to progress in the near future. The worldwide increase in the generation of refinery wastewater along with strict environmental regulations in the discharge of industrial effluent, persistent efforts have been devoted to recycle and reuse the treated water. The wastewater from the refining operation leads to serious environmental threat to the ecosystem. Therefore, this study aimed to synthesize silica (SiO 2) and calcium carbonate nanoparticles (CaCO 3) in the reduction of organics from refinery wastewater. The synthesized nanoparticles were employed in the reduction of chemical oxygen demand (COD) from refinery wastewater by studying the influence of solution pH, contact time, dosage of nanoparticles and stirring speed on adsorption performance. From the batch experimental studies, the optimized processing conditions for the reduction of COD using SiO 2 nanoparticles are pH 4.0, dosage 0.5 g, stirring speed 125 rpm and 90 min stirring time, and the corresponding values for CaCO 3 nanoparticles are pH 8.0, dosage 0.4 g, stirring speed 100 rpm and 90 min stirring time. The study demonstrates that SiO 2 and CaCO 3 nanoparticles have a promising future in the reduction organics from refinery wastewater in different pH regimes. 相似文献
14.
Poly(methyl methacrylate) (PMMA) microcapsules were prepared by the in situ polymerization of methyl methacrylate (MMA) and N, N′-methylenebisacrylamide on the surface of calcium carbonate (CaCO 3) particles, followed by the dissolution of the CaCO 3 core in ethylenediaminetetraacetic acid solution. The microcapsules were characterized using fluorescence microscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The average sizes of the CaCO 3 particles and PMMA capsules were 3.8 ± 0.6 and 4.0 ± 0.6 μm, respectively. A copolymer consisting of MMA and rhodamine B-bearing MMA was also used to prepare microcapsules for fluorescent microscopy observations. Fluorescein isothiocyanate-labeled bovine serum albumin was enclosed in the PMMA microcapsules and its release properties were studied. 相似文献
15.
The hyperbranched aliphatic polyester grafted calcium carbonate nanoparticles (HAPE‐CaCO 3), was successfully prepared by the real one‐pot method. The AB 2 monomer, 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA), was used as both the surface modifying agent and the monomer of the hyperbranched aliphatic polyester. It introduced the organic active group (hydroxyl group) onto the surfaces of the calcium carbonate nanoparticles (nano‐CaCO 3) and its polycondensation took place subsequently, with the catalysis of p‐toluenesulfonic acid (p‐TSA). The HAPE‐CaCO 3 had been characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), and transmission electron microscope (TEM). 相似文献
16.
Feasibility studies directed at the parallel increase in the elastic modulus and impact toughness of polypropylene via introduction of ultradispersed CaCO 3 particles with sizes of 100 (Socal U1S2) and 60 nm (Socal 312V) have been performed. The effects of the content and sizes of CaCO 3 particles and the nature of a surfactant on the character of distribution of particles, the thermophysical characteristics of the polymer matrix, and the mechanical characteristics and heat resistance of the nanocomposites are analyzed. Microscopic studies reveal that nanoparticles show a tendency toward structuring. DSC studies have proved the nucleating action of ultrafine particles during the crystallization of PP. For the composites containing 15 vol % of Socal 312V CaCO 3 nanoparticles, the increase in the tensile elastic modulus achieves its maximum; depending on the nature of the surfactant, the reinforcing effect increases by 70-40%. As compared to the initial PP, the presence of ultrafine particles in the composites prevents a decrease in the storage modulus of PP with increasing temperature from 0 to 50°C; as a result, the reinforcing effect increases from 30-40% at temperatures below the glass transition temperature to 40–75% at 50°C. For the nanocomposites with U1S2 in the presence of Triton X-100 or fluorinated alcohol telomer, the impact toughness increases over the entire filler content interval; when the filler concentration is 15 vol %, the impact toughness of nanocomposites is higher than that of the initial PP by factors of 3 and 4.5, respectively. It has been found that nanocomposites containing 5 vol % CaCO 3 nanoparticles show the effect of thermal stabilization, which comes up to about 50°C. 相似文献
17.
In the present experiments, the monodisperse calcium carbonate nanoparticles obtained in the reactor (three-phase reaction) with rotating discs have been covered with α-cyclodextrin. Both pure CaCO3 nanoparticle and α-cyclodextrin-coated CaCO3 powders were deeply analysed by the use of the scanning electron microscope, the dynamic light scattering and the thermogravimetric method. The experimental data have allowed for determination of effective diameter of the obtained particles (aggregates of ca. 30 nm single crystals) and their size distribution (almost monodisperse—ca. 390 nm) as well as for distinction between α-cyclodextrin molecules present on calcite surface or free α-cyclodextrin molecules if presented in the sample. It was found that the nanometric CaCO3 obtained in the reactor with rotating discs can be covered with a maximum of 1.15% α-cyclodextrin monolayer. The maximal coverage of the CaCO3 calcite particles with α-cyclodextrin can be done by 24-h shaking of 50 mg nanometric calcium carbonate with 25 mg of 36.79 mM α-cyclodextrin aqueous solution.
相似文献
18.
Nanocomposites based on poly(methyl methacrylate) (PMMA) and TiO 2 nanoparticles were synthesized by in situ radical polymerization of MMA in solution. The surface of TiO 2 nanoparticles was modified with four gallic acid esters (octyl, decyl, lauryl and cetyl gallate). The content of gallates present on the surface of TiO 2 was calculated from the TGA results. The influence of length of hydrophobic tail of amphiphilic alkyl gallates on dispersability of surface modified TiO 2 nanoparticles in PMMA matrix, the molecular weight and glass transition temperature of PMMA, as well as the thermal stability of the prepared PMMA/TiO 2 nanocomposites in nitrogen and air was investigated. The influence of content of TiO 2 nanoparticles on the properties of these nanocomposites was also examined. The formation of a charge transfer complex between the surface Ti atoms and the gallates was confirmed by FTIR and UV spectroscopy. TEM micrographs of the PMMA/TiO 2 nanocomposites revealed that degree of TiO 2 aggregation can be significantly lowered by increasing the length of aliphatic part of the used gallates. The molecular weight of PMMA slightly decreases with the increase of TiO 2 content, indicating that used TiO 2 nanoparticles act as radical scavengers during the polymerization of MMA. The presence of surface modified TiO 2 nanoparticles do not have an influence on the mobility of PMMA chain segments leading to the same values of glass transition temperature for all investigated samples. Thermal and thermo-oxidative stability of the PMMA matrix are improved by introducing TiO 2 nanoparticles modified with gallates. 相似文献
19.
Modified calcium carbonate (CaCO 3) nanoparticles with cubic- and spindle-like configuration were synthesized in situ by the typical bobbling (gas-liquid-solid) method. The modifiers, such as sodium stearate, octadecyl dihydrogen phosphate
(ODP) and oleic acid (OA), were used to obtain hydrophobic nanoparticles. The different modification effects of the modifiers
were investigated by measuring the active ratio, whiteness and the contact angle. Moreover, transmission electron microscopy
(TEM), X-ray diffraction (XRD) and thermogravimetry analysis (TGA analysis) were employed to characterize the obtained products.
A preliminary reaction mechanism was discussed. According to the results, the active ratio of CaCO 3 modified by ODP was ca. 99.9% and the value of whiteness was 97.3% when the dosage of modifiers reached 2%. The contact angle
was 122.25° for the CaCO 3 modified in the presence of sodium stearate, ODP and OA. When modified CaCO 3 was filled into PVC, the mechanical properties of products were improved greatly such as rupture intensity, pull intensity
and fuse temperature. The compatibility and affinity between the modified CaCO 3 nanoparticles and the organic matrixes were greatly improved.
Supported by the National Natural Science Foundation of China (Grant No. 50372025) 相似文献
20.
The effects of calcium carbonate (CaCO 3) and calcium sulfate (CaSO 4) nanoparticles on the thermal and UV-absorbing properties of polyvinyl acetate (PVAc) were analyzed in this study. Nanoparticles of CaCO 3 and CaSO 4 were synthesized by in situ deposition technique. The size and shape of nanoparticles were recognized by X-ray diffraction and scanning electron microscope (SEM) analyses which confirmed that the particle was having a diameter of 25–33 nm. In this technique, the surface modification of nanoparticles was done by non-ionic polymeric surfactant. PVAc/CaCO 3 and PVAc/CaSO 4 nanocomposites film samples with an average thickness of 30 µm and in the mass ratio of nanoparticles (0–4% (w/w)) were prepared by solution mixing technique. Chemical, structural, and elemental characterizations of nanocomposites were done by, fourier transform infrared, SEM, and energy dispersive X-ray spectroscopy analyses, respectively. Thermal properties of pure polymer and nanocomposites were characterized through differential scanning calorimetric, thermogravimetric, and differential thermogravimetry techniques. The glass transition temperature of nanocomposites increases with increase in content of nanoparticles. It may be due to the interaction between inorganic and organic components. The thermogravimetric analysis results indicate that the thermal degradation temperatures of nanocomposites were enhanced upon the addition of nanosized inorganic fillers. The thermal results show that PVAc/CaSO 4 nanocomposites were more thermally stable than PVAc/CaCO 3 nanocomposites. The addition of nanoparticles affects degradation mechanism and consequently improves thermal stability of PVAc. The reduction of polymer chain mobility and the tendency of nanoparticles to eliminate free radicals were the principal effects responsible for these enhancements. The ultraviolet–visible (UV–Vis) absorbance spectra of PVAc and its nanocomposites films show that the intensity of absorbance increases with increasing filling content, suggesting that nanocomposites films have greater UV-shielding property. 相似文献
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