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1.
利用原位自由基聚合方法合成了聚丙烯酰胺/纳米SiO2复合凝胶,并用红外光谱测定了凝胶化过程中几个典型的反应阶段的红外光谱图,结果表明,复合材料在凝胶化过程中,不仅存在聚合交联反应,同时内部还可能有氢键的形成或其他一些化学作用.用光学显微镜观察了不同纳米粒子含量的复合凝胶的表面形貌,研究表明,纳米粒子在凝胶中并没有出现团聚,表面仍为均匀体系.  相似文献   

2.
本文通过将纳米氧化锌(ZnO)颗粒加入熔融的石蜡(PW)并进行搅拌和超声制备了一种纳米ZnO/PW复合相变储能材料。为使纳米氧化锌在基体物质中分散均匀,在制备过程中使用了搅拌和超声以制备均匀的复合材料。使用扫描电镜观察其微观结构表明氧化锌在石蜡中分散良好。对所得ZnO/PW复合相变材料的相变温度、相变焓及导热系数等热物...  相似文献   

3.
针对Ziegler-Natta/茂金属复合催化剂基于Spheripol工艺制备的聚丙烯釜内合金的初生粒子中存在的两种外观形貌的粒子,采用红外光谱(FTIR)、核磁共振(NMR)、扫描电镜(SEM)、偏光显微镜(POM)、热分析(DSC)和力学性能测试等方法对白色和半透明的初生态树脂粒子进行了组成、结构和力学性能的比较研究。FTIR,NMR和SEM结果表明,两者外观形貌的差异主要是二段聚合中乙烯-丙烯共聚物的含量和分布不同。DSC和POM结果表明,乙烯-丙烯共聚物的存在使半透明粒子中聚丙烯的结晶速率高于白色粒子。力学性能测试结果表明,由于乙烯-丙烯共聚物含量少,白色粒子的冲击韧性明显低于半透明粒子,但拉伸强度和弯曲模量明显高于半透明粒子。并基于聚合工艺提出了两种初生粒子形成的可能机理。  相似文献   

4.
合成聚丙酰胺-硫属半导体复合纳米材料的新技术   总被引:1,自引:0,他引:1  
在水溶液体系中采用同步聚合-水解技术制备聚丙烯酰胺-半导体纳米复合材料,该SPH技术是基于丙烯胺单体的聚合和MS纳米粒子的形成同步发生,使生成的半导体纳米粒子可均匀分散在聚丙烯酰胺基质中,该技术还为制备其它有机聚合物-金属硫化物纳米复合物提供了一种新途径。  相似文献   

5.
采用分散聚合反应制备了纳米SiO2/PS包覆粒子,并对其结构进行了表征。首先在超声波场中用表面活性剂对纳米SiO2粒子进行亲油化处理,然后在氮气保护下利用超声波的分散、粉碎、活化、引发等多重作用,在实现纳米SiO2粒子在反应介质中纳米分散的同时,引发苯乙烯单体在纳米SiO2粒子表面发生分散聚合反应,制备出纳米SiO2/PS包覆粒子。最后,采用SEM,TEM,FTIR,XPS等测试手段对纳米SiO2/PS包覆粒子进行了表征,测试结果表明,PS实现了对纳米SiO2的包覆,形成了核壳包覆结构。  相似文献   

6.
相转变—微波法制备匀分散α—Fe2O3胶体粒子   总被引:5,自引:0,他引:5  
用相转变-微波法制备了均分散α-Fe2O3胶体粒子。实验表明,采用微波辐照并加入CTAB表面活性剂,可有较短时间内,制备出均分散的α-Fe2O3胶体粒子。所得粒子呈均分散的假立方体,比常法制得的粒子小,产率高。讨论了微波辐照和不同的表面活性剂对粒子形状的影响,得出CTAB阳离子表面活性剂有利于均分散α-Fe2O3假立文体的形成。用时间分辨TEM和FTIR对粒子的形成过程进行了研究,认为在粒子成长过  相似文献   

7.
溶胶-凝胶法制备Polyme/MS/SiO2(M=Pb,Cd)复合纳米材料   总被引:4,自引:1,他引:3  
采用溶胶-凝胶结合水热结晶技术,可成功把高聚物引入MS-SiO2网络结构。合成一种新型的有机-无机硫化物即Polymer/MS/SiO2(M=Pb,Cd)复合纳米材料,其中聚甲基丙烯酸甲酯或聚丙烯酰胺等高聚物的引入将有效地防止无机粒子团聚,控制粒子尺寸,前者还能形成核-壳结构复合粒子。作者还详细讨论了该复合纳米材料的热分析,结果表明,聚合物的存在提高了原有MS-SiO2(M=Pb,Cd)材料的热稳定性。  相似文献   

8.
《光散射学报》2017,(4):314-319
本文通过将单分散Fe_3O_4胶体粒子分散嵌埋于琼脂糖水凝胶网络结构中,制备了一种新型磁响应光子晶体水凝胶,并对其光学性质进行了研究。首先通过水热法制备了由表面羧基修饰的Fe_3O_4胶体粒子,并将其分散于水中制成胶体溶液。将该胶体溶液与琼脂糖单体混合,通过交联聚合使之形成琼脂糖水凝胶。由于琼脂糖水凝胶较大的网络空间结构,使得Fe_3O_4胶体粒子仍能保持其可动性,在外加磁场作用下,处于水凝胶网络中的Fe_3O_4胶体粒子可以对磁场做出响应并形成晶态胶体阵列,且随着磁场强度的变化,凝胶的结构色也表现为连续可调的特性。这种结构色可动态调控的光子晶体水凝胶,为胶体光子晶体的实际应用提供可能。  相似文献   

9.
聚氨酯/聚丙烯酸酯复合乳液的紫外光谱研究   总被引:1,自引:1,他引:0  
以水性聚氨酯(PU)分散液为种子,采用无皂乳液聚合技术合成出了聚氨酯/聚丙烯酸酯(PUA)复合乳液。紫外光谱研究发现,PU乳液的,n-π迁紫外吸收峰的λmax随溶液浓度增加明显红移。对于PU分散液,随着亲水性扩链剂用量增加,紫外光谱吸光度值变小;随着NCO/OH摩尔比增大,吸光度增大。对于PUA复合乳液,亲水性扩链剂用量取7.5%时,吸光度值最小;而第二阶段聚合引发剂种类对紫外光谱影响不大。紫外光谱的吸光度值反映了乳液粒子平均粒径的大小;随着NCO/OH摩尔比增大,吸光度增大。对于PUA复合浮液,亲水性扩链剂用量取7.5%时,吸光度值最小;而第二阶段聚合引发剂种类对紫外光谱影响不大。紫外光谱的吸光度值反映了乳液粒子平均粒径的大小。  相似文献   

10.
在4℃避光条件下,将藻蓝蛋白(简称PC)与AgNO3作用,通过UV,FS,FTIR等谱学方法研究了PC与Ag(Ⅰ)原位还原与纳米Ag(0)粒子形成的动态过程。结果显示:PC在615nm的特征吸收峰强度明显减弱,并随Ag(Ⅰ)浓度增加和时间延长单调降低;PC的荧光发射峰和荧光激发峰也均呈现衰减趋势。同步荧光光谱观察到纳米Ag(0)粒子形成的动态过程。用TEM观察到所形成的Ag(0)分散于PC表面,形成PC为核,纳米银为壳部分包覆的生物缀合物,粒子呈球形,有较窄的分布尺寸,粒径在15~30nm之间。  相似文献   

11.
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.  相似文献   

12.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   

13.
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.  相似文献   

14.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   

15.
A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.  相似文献   

16.
17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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