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1.
In this article, the Young's modulus and the loss tangent of polydimethylsiloxane (PDMS) is obtained in the frequency range between 10 and 1500 Hz using an optical technique. The first three mechanical modes of vibrating PDMS beams are detected by measuring the tip rotational displacement using an optical lever. The experiments are carried out for 10:1 and 20:1 volume mixing ratios between the polymer base and the curing agent. The experimental results show that the Young's modulus varies between 1 and 2.6 MPa for 10:1 while its values are between 0.6 and 1.1 MPa for 20:1. The loss tangent is between 0.2 and 0.4 for 10:1 and 0.2 and 0.5 for 20:1. However, the measured values of the loss tangent are greater than the values reported in ref. 13. We also found that if the PDMS is not cured properly, its mechanical properties are time dependent. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 747–751  相似文献   

2.
申书昌  蔡君洋  王利鸿 《应用化学》2016,33(9):1085-1092
以对苯二胺、3-氯丙醇和4-羟基苯甲醛为原料,合成对苯二(对苯丙氧基醇)亚胺液晶基元,再与对苯二异氰酸酯和1,3-双(3-氨基丙基)四甲基二硅氧烷反应,合成席夫碱型硅氧烷聚氨酯液晶聚合物。 通过红外光谱法、X射线衍射、热分析、偏光显微镜等技术手段对其结构和性能进行了表征。 结果表明,该物质为席夫碱有机硅聚氨酯液晶聚合物,属于近晶相液晶,液晶区间为103~150 ℃,热分解温度为300 ℃。 用席夫碱型硅氧烷聚氨酯液晶固定相制备填充色谱柱,考察固定液的相对极性及其对取代苯位置异构体的色谱分离性能。 合成的席夫碱型硅氧烷聚氨酯液晶聚合物的液晶温度范围为103~146 ℃,属于强极性固定液(Px=79),各组分色谱峰的分离度为0.96~3.33。  相似文献   

3.
The decay in birefringence of glassy polycarbonate held at constant extension has been studied at 23°C, in the time-scale range 10–103 sec, up to about 6% strain. The results show that, under these conditions, the birefringence can be validly expressed as a linear hereditary integral of the strain history up to a relatively high strain level which is about 3.4% for an experimental time-scale of 100 sec. Comparison with previously obtained data on the stress relaxation behavior of the same polymer shows that, other factors remaining constant, mechanical relaxation is linear only up to about 1.1% strain. The earlier onset of mechanical nonlinearity is discussed and it is suggested that the mechanical relaxation spectrum is richer than the optical spectrum in relatively long relaxation times, corresponding to relatively slow molecular motions. It is further suggested that these slow molecular motions are accelerated first as the polymer is extended beyond the limit of linear viscoelastic behavior. The observed nonidentity between strain limits for linear mechanical and linear optical behavior is discussed in the light of current practices in photomechanical stress analysis.  相似文献   

4.
Summary: Several salicylaldiminate M(II) complexes of Nickel, Copper and Cobalt have been prepared and mixed with ethylene based polymers in order to prepare new composite materials with interesting morphological and optical properties by profiting of the presence of alkyl chains and push-pull substituents connected to the ligand structure. The phase dispersion behaviour of the binary films has been studied by scanning electron microscopy (SEM) and x-ray microanalysis, whereas the optical properties of the composite samples have been evaluated by UV-vis and fluorescence spectroscopy. The results in absorption have been analysed in terms of the anisotropy induced by the mechanical orientation of the polymer matrix and by the role of the metal centre according to the different strength of the complexes transition dipole moment. The luminescence behaviour have been discussed in terms of potential developments aimed at preparing polymeric supported Schiff base ligands for metal ions sensor applications.  相似文献   

5.
聚合物基纳米复合物(PNCs)具有比传统高分子材料更加优异的光学、力学、热力学等性能,广泛应用于各个工程领域.而纳米粒子(NPs)对材料性能提高的机理则是当前聚合物纳米复合物领域研究的重要问题,聚合物纳米复合体系相互作用的影响因素众多,至今尚未明确并完整建立复合体系相互作用与性能增强之间的关系.本文总结了近年来关于纳米粒子填充聚合物基体力学性能的研究,从粒子-聚合物相互作用和粒子-粒子相互作用角度阐述了聚合物纳米复合体系力学性能的增强机理,并根据体系中不同的结构关系分别总结了聚合物/未改性纳米粒子复合体系和聚合物/聚合物接枝纳米粒子复合体系中影响力学性能的因素.该部分内容具有重要的理论和实践意义,有助于构建复合体系微观结构与宏观性能之间的关系,进而对微观层面调控PNCs的力学性能提供指导.  相似文献   

6.
This work presents the influence of dopants on viscosity in an uncured liquid state as well as on refractive index, Abbe number, optical loss, and glass transition temperature of different polymer compositions. The base material consists of Genomer 2263, a bisphenol, an epoxy diacrylate as matrix polymer, and benzyl methacrylate as comonomer. As dopants, the soluble aromatic guest‐molecules 9‐bromophenantrene and 9‐vinylcarbazole are investigated. The viscosity can be adjusted by different mixtures of the matrix polymer and comonomer from 3000 down to 4 mPa sec. Depending on the type and content of the dopants, the refractive index, Abbe number, and the glass transition temperature can be adjusted. The refractive indices increase linear at 589 nm and 20°C from 1.572 to 1.638 by doping, with Abbe numbers between 20 and 30. At this wavelength, the optical losses were determined to be around 2 dB · cm?1. The glass transition temperature can be tailored between 50 and 98°C. A way to use high amounts of optical dopants is presented, which opens up the way for different shaping technologies like inkjet printing of optical components. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

7.
Polyamides containing main-chain cyanine chromophores are synthesized, and their molecular, nonlinear optical, and mechanical properties are studied. It is shown that the Kerr electro-optical effect in polymer solutions is determined by the rigidity of polymer chains and that the nonlinear optical properties are dependent only on the chromophore content.  相似文献   

8.
A new polymer blend composed of a hydrogenated ring‐opening polymer (HROP) with an ester group and hydroxyl functionalized polystyrene (HFP) produced the excellent transparent materials which enabled a precise birefringence control in keeping with the other physical properties for optical film use. The blend with a composition from 0.28 to 0.35 for the HFP weight fraction showed an extraordinary wavelength dispersion, transmitting through a zero birefringence point at the critical fraction of 0.45, while each polymer showed an ordinary wavelength dispersion. The observed excellent transparency even above those of the glass transition temperature was attributed to a depressed phase separation that resulted from strong hydrogen bond between the ester and hydroxyl groups. An IR analysis of the film demonstrated a remarkable red‐shift in the carbonyl peak with an increase of the hydroxylated polystyrene content, indicating a strong hydrogen bond between those groups. This new polymer blend provides a useful design to achieve practical demands for film use, both optical and mechanical under the fabrication conditions using the melt extrusion technique. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3132–3143  相似文献   

9.
为明确空间级硅橡胶的化学组成及填料添加对材料物理性能的影响, 采用填料复合方式制备硅橡胶高聚物材料, 并通过化学成分测试、 原子氧暴露试验及力学性能测试等研究其结构组成与物理性能. 经微观粒径测试得出硅橡胶中白炭黑填料粒径主要分布在8~16 μm; 经傅里叶变换红外光谱(FTIR)、 核磁共振波谱( 1H NMR和 29Si NMR)和溶胶凝胶渗透色谱(GPC)测试得出硅橡胶中含有Si—Me, Si—Ph, Si—O—Si等基团和甲基、 苯基等官能团, 其分子量分散系数为1.56, 并进一步推断出硅橡胶的分子结构及基胶与交联剂的反应类型为脱羟胺型; 经原子氧暴露试验及力学试验证实, 与未改性白炭黑填充的硅橡胶高聚物材料相比, 经硅烷改性白炭黑填充的硅橡胶高聚物材料表现出更好的抗原子氧性能, 动态力学测试后储能模量高54%, 并具有更好的应力应变响应性能. 研究结果表明, 采用表面改性处理方式可增强填料与硅橡胶基质的相互作用, 从而提高填料复合型硅橡胶高聚物材料的抗原子氧性能及综合力学性能.  相似文献   

10.
As a novel material of low loss and high thermal stability, a graded index plastic optical fiber (GI POF) comprised of a copolymer of methyl α‐chloro acrylate (MCA) and 2,2,2‐trichloroethyl methacrylate (TCEMA) was prepared and the thermal, mechanical, and optical characteristics were investigated. Although each homopolymer had low loss and desirable high thermal stability, they had crucial disadvantages for the fiber fabrication process. To draw a MCA polymer (PMCA) fiber, it has to be heated above 270 °C. However, the polymer started to decompose at a lower temperature and produced numerous bubbles. In contrast, TCEMA polymer (PTCEMA) is too brittle to roll up during heat drawing. In this study, we succeeded to improve the strong viscoelasticity and the low decomposition temperature of PMCA and the brittleness of PTCEMA by copolymerizing MCA and TCEMA. In addition, the glass transition temperatures (Tg) of the copolymers were in the range of 133–147 °C and the transmittances of the copolymers were much higher than that of PMMA which has been commonly used as a base material of POF. A suitable GI POF was obtained using the MCA and TCEMA copolymer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3352–3361, 2009  相似文献   

11.
The ultra-violet (UV) irradiation induced modification of the mechanical and optical properties of several polymer composites containing 4-aminostyrene and glycidyl methacrylate and their dependences on radiation dose, structure and ageing have been investigated. The nano- and microindentation techniques were used for determination of the mechanical parameters of as-grown and irradiated materials. The light-induced structural changes result in an increase of the hardness and elastic modulus of the polymer layers up to five and three times, respectively. It is also shown that the influence of polymer structure is significant. The conditions for improvement, degradation and stabilization of physical properties by UV irradiation were established. Load and depth sensing indentation has proved to be a powerful tool for an accurate estimation of mechanical properties of cross-linking polymer compositions. Variable-energy positron annihilation spectroscopy (slow-positron beam technique) was developed to measure defect depth profiles in the near-surface region. The increase of S-parameter with the increase of nano-hardness and elastic modulus has been determined for these materials.  相似文献   

12.
Biodegradable PLA composites were prepared using microcrystalline cellulose (MCC) and silver (Ag) nanoparticles. The main objective of the present study is to develop new biopolymer composites with good mechanical properties, thermal stability, maintaining the optical transparency and also providing antimicrobial properties through silver nanoparticle introduction. Composites were prepared with 1%wt of Ag nanoparticles and 5%wt of MCC using a twin-screw microextruder; film parameters were optimized in order to obtain a thickness range between 20 and 60 μm.PLA composites maintained optical transparency properties of the matrix, while MCC was able to reduce polymer permeability. Thermal analysis revealed that MCC increased PLA crystallinity and the mechanical properties of the composites demonstrated that tensile modulus was improved by microcrystalline cellulose.  相似文献   

13.
The degradation of polystyrene nanocomposite was carried out by mechanical recycling after multiple processing of thermo-oxidative ageing. It was found that the degradation of the quaternary salt present in the clay promotes degradation of the polymer. The clay exfoliation was affected by the nanocomposite degradation process as well as the dipolar interactions of polymer chains, which influences the physical and mechanical properties of the final nanocomposite. NMR is a powerful tool for the characterization at the molecular level; it is sensitive to variations in local segmental and global movements. The correlation between NMR relaxation and rheological analyses in polymer nanocomposites was observed. This study aims to understand the complex effects of degradation in polymeric systems containing nanoparticles. Several 1H NMR relaxation parameters were analyzed. From the base line of the domain curves, the dipolar interaction phenomenon in polystyrene chains was investigated. The polymer chain heterogeneity was determined quantitatively from the MSE-FID, using a combination of Abragamian, Gaussian and exponential functions to fit experimental data. At least three domains: rigid, intermediate and mobile phases were identified based on the molecular mobilities.  相似文献   

14.
In this note rheological properties of two different polymer modified asphalts (PMA) are compared. PMAs were prepared from two different base asphalts, a soft one (200/300 Pen grade) and a hard one (70/100 Pen grade), by addition of 4% by weight of radial SBS as modifier. Dynamic mechanical properties were determined in a wide temperature range for bases and modified asphalts both before and after artificial aging. As expected, the moduli of the soft base are more sensitive to polymer addition and the two PMAs attain similar maximum values after aging. However a significant difference in the frequency at which the maxima of the loss modulus are reached is maintained within the two materials irrespectively of aging or polymer addition.  相似文献   

15.
Sol-gel optical composites doped with optically active materials prepared by the post-doping method have been characterised in relation to their optical and structural properties. The dopants of interest have been found to be homogeneously distributed throughout the gel matrix. The in-situ impregnation of an index-matching polymer such as PMMA within the porous structure improves both the optical and mechanical properties of the composites significantly. The as-prepared materials have a non-porous feature and show a low optical loss.  相似文献   

16.
By application of different unique microphotometric sensors it is possible to detect and quantify disturbing particles (gels, unmolten resins, black spots, additive agglomerates, bubbles) within a flowing polymer melt in realtime during extrusion processing. These particles result in disadvantageous optical and mechanical properties of a final polymer product. Sensors can be adapted inline and online to different extruders at various positions. This seems to give technical and economic benefit to quality control and process optimisation in polymer processing.  相似文献   

17.
<正>The existence of interfacial instability at the interface of multilayer polymeric flows is well known.This article is designed mainly to provide guidelines for the development of experimental techniques for the improvement of two-layer polymer products in the polymer processing industry.This is done by performing a series of tensile tests on extrudate two-layer polymer melts in order to get insight into the relation between interfacial wave and mechanical properties of LLDPE/HDPE polymer system.Observed variations of the mechanical properties have been related to the conformation of the interfacial wave so that a relationship between interface morphology corresponding to extrusion instabilities and mechanical characteristics of the interfacial strength for polymer melts extrudate is established.  相似文献   

18.
Discussion is presented on the use of the photoisomerization of azobenzene chromophore in the design andpreparation of novel functional materials. The two systems reviewed are azobenzene polymer-stabilized liquid crystals andazobenzene elastomers. In the first case, a polymer network containing azobenzene moieties is used to optically induce andstabilize a long-range liquid crystal orientation without the need of treating the surfaces of the substrates. This optical andrubbing-free approach was applied to nematic and ferroelectric liquid crystals. In the second case, an azobenzene side-chainliquid crystalline polymer is grafted onto a styrene-butadiene-styrene triblock copolymer to yield a photoactive thermoplasticelastomer. Coupled mechanical and optical effects make possible the formation of dimaction gratings that may be useful formechanically tunable optical devices.  相似文献   

19.
A new, more realistic optical model of a dilute polymer solution is used to calculate the intrinsic birefringence. A general formula is derived valid for an arbitrary equilibrium distribution function of particles in the system. Besides the contributions due to the polymer and solvent, the resulting relation for intrinsic birefringence also contains terms reflecting the effect of orientation of solvent surrounding the polymer chain and the contribution of optical interactions between polymer segments and molecules of solvent. A detailed discussion of the optical interactions in an isotropic solvent reveals that the problem may be transformed in the first approximation into that of interactions between excess dipoles; however, any separation of the macroform and microform effects has no theoretical justification. It is shown that the microform effect depends on a detailed optical model of the statistical segment, and this effect is calculated for two simple models. The expression suggested by Tsvetkov cannot be applied to a segment consisting of anisotropic monomers.  相似文献   

20.
Li  Hongbing  Zong  Yudong  Li  Xia  Ding  Qijun  Jiang  Yifei  Han  Wenjia 《Cellulose (London, England)》2021,28(17):10707-10714
Cellulose - Cellulose is the most widely distributed polymer material in nature and is considered a low-cost, green and recyclable material. Because of its excellent mechanical, optical and thermal...  相似文献   

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