共查询到20条相似文献,搜索用时 125 毫秒
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目的通过二维红外光谱技术研究温度对聚丙烯化学结构的影响。方法在1500~1350 cm-1的频率范围内,分别测定聚丙烯C—H弯曲振动模式(δC-H)的一维红外光谱、二阶导数红外光谱和四阶导数红外光谱来确定聚丙烯分子结构,后采用二维红外光谱研究温度对聚丙烯δC-H红外吸收强度的影响。结果聚丙烯δC-H主要包括甲基不对称碳氢弯曲振动模式(δas CH3)、甲基对称碳氢弯曲振动模式(δs CH3)和亚甲基碳氢弯曲振动模式(δCH2),随着测定温度的升高,聚丙烯分子中δC-H红外吸收强度变化快慢顺序为δCH2-2(1464 cm-1)δCH2-1(1475 cm-1)δas CH3(1455 cm-1)δs CH3(1375 cm-1)。结论二维红外光谱在有机高分子包装材料热变性分析具有重大作用。 相似文献
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通过接枝和缩合反应制备了支化多酚羟基乙丙橡胶(PHEPDM),利用全反射傅立叶变换红外光谱仪(ATR-FT-IR)、核磁共振(NMR)对其结构进行了研究。ATR-FT-IR测试结果表明,在PHEPDM的制备过程中,硅烷偶联剂A171可以接枝到三元乙丙橡胶(EPDM)的分子链上,且其分子结构中的Si-OCH3可以和双酚A中的酚羟基发生缩合反应;1H-NMR谱测试结果显示PHEPDM分子结构中存在与苯环和与Si相连的亚甲基上H的核磁振动峰,13C-NMR谱显示分子结构中含有与O相连的亚甲基上C的振动峰及苯环上C的振动峰。 相似文献
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CllIR/PS接枝共聚物研究——Ⅰ分子结构参数的测定 总被引:2,自引:1,他引:1
本文用红外光谱(IR)、凝胶渗透色谱(GPC)、膜渗透压(OS)等测试方法研究了氯化丁基橡胶-聚苯乙烯接枝共聚物(ClIIR/PS)的分离提纯程序以及分子结构。得到了接枝共聚物分子量,PS支链分子量、分子量分布、接枝数、枝化程度等分子结构参数。并根据GPC谱图,研究了接枝共聚物的分子结构以及溶液中共聚物的分子形态。 相似文献
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现代化学学科近年来在簇化学(Cluster chemistry)研究领域的蓬勃发展,带动了碳簇化学的深入研究和重大突破.1985年H.Kroto等首次提出了C_(60)分子结构的设想,即由60个碳原子组成的簇,它酷似一支欧洲足球(Soccer ball)即自12个五元环和20个六元环拼接成的一个园笼形分子.设想提出后(首创者将其命名为Buckminsterfulle rene以纪念结构上酷似此足球的笼形房顶的创始人Buckminster Fuller),即引起了国际化学界广泛重视和讨论.其中,怀疑和否定Buckminsterfullerene的实际存在者 相似文献
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《高分子材料科学与工程》2015,(11)
应用高分辨率热解气相色谱-质谱(HRPyGC-MS)研究溴化天然橡胶(BNR)的结构。结果表明,溴化天然橡胶热解产物中含有苯同系物和多环芳烃,但不含溴代苯和多溴苯。随着BNR中溴含量的增大,热解产物中2-甲基-1,3-丁二烯的含量逐渐减少直至消失,而环烯烃和芳香族化合物含量则逐渐增大。温度升高时,体系中甲苯和苯同系物的含量增大,而多环芳烃含量则大为减少。天然橡胶溴化过程中主链结构发生改变,可能伴随着环化反应,溴化天然橡胶产物分子链上可能存在六元环状结构。 相似文献
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硅氧树脂 Si-O 键伸缩振动模式ATR红外光谱研究 总被引:1,自引:0,他引:1
在303~393 K 温度范围内,采用变温傅里叶变换衰减全反射红外光谱(ATR-FTIR)技术分别测定硅氧树脂的一维红外光谱、二阶导数红外光谱和四阶导数红外光谱。研究发现,在1800~600 cm-1范围内,聚硅氧树脂主要存在着 CH 3伸缩振动模式(νCH3)、CH 3变形振动模式(δCH3)、CH 3摇摆振动模式(ρCH3)、Si-O 伸缩振动模式(νSi-O )和 Si-C 伸缩振动模式(νSi-C )。在1100~1000 cm-1范围内,以νSi-O 为研究对象,研究了温度对硅氧树脂分子结构的影响。实验发现,随着测定温度的升高,硅氧树脂νSi-O 的主要红外吸收频率出现了明显的红移现象。进一步研究了硅氧树脂νSi-O 的二维红外光谱,考查温度对于νSi-O 红外吸收强度的影响。研究发现,随着测定温度的升高,硅氧树脂νSi-O 红外吸收强度的变化快慢顺序为:1024 cm-1>1096 cm-1>1010 cm-1>1076 cm-1>1083 cm-1>1064 cm-1。本研究拓展了 ATR-FTIR 技术在硅氧树脂材料热变性方面的研究范围。 相似文献
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以三氯化硼(BCl_3)、三氯硅烷(Si HCl_3)、六甲基二硅氮烷(Me_6Si_2NH)为原料,通过共缩聚一步法制备了小分子前驱体,然后经过聚合得到聚硼硅氮烷前驱体(PBSZ),后经熔融纺丝、不熔化处理、高温热解制备出硅硼氮(Si BN)陶瓷纤维。利用FT-IR、NMR、TG、XRD及TEM等分析手段对Si BN陶瓷纤维的组成结构及高温稳定性能进行了表征。研究表明,热解后的Si BN陶瓷纤维主要包括Si N_4及BN_3结构,其中B—N以六元环形式存在,基本实现了无机化转变,在850℃时失重约为1%,在1 400℃仍然保持非晶结构,具有较好的高温稳定性。 相似文献
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在303~393 K温度范围内,采用变温傅里叶变换衰减全反射红外光谱技术(ATR-FTIR)研究了二甲基硅油的一维红外光谱、二阶导数红外光谱、四阶导数红外光谱和去卷积红外光谱。实验发现,在1800~600 cm~(-1)范围内,二甲基硅油主要存在CH_3伸缩振动模式(νCH_3)、CH_3变形振动模式(δCH_3)、CH_3摇摆振动模式(ρCH_3)、Si-O伸缩振动模式(νSi-O)和Si-C伸缩振动式(νSi-C)等5种红外吸收模式,其中782 cm~(-1)和789 cm~(-1)处的红外吸收峰归属于二甲基硅油νSi-C。以二甲基硅油νSi-C为研究对象,进一步开展相关二维红外光谱的研究。结果发现,随着测定温度的升高,二甲基硅油νSi-C红外吸收强度的变化快慢顺序为:789 cm~(-1)782 cm~(-1)。本项研究拓展了ATR-FTIR技术在二甲基硅油热变性方面的研究范围。 相似文献
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Nishikant Sonwalkar Sidney Yip S. Shyam Sunder 《Journal of Computer-Aided Materials Design》1995,2(2):77-100
Summary Understanding the structure and interatomic interactions of an ice-metal interface plays a fundamental role in the design of deicing coatings. This is demonstrated by a novel approach, combining vibrational results from laser Raman spectroscopy with molecular dynamics simulations to obtain insights into icing on solids which, in turn, lead to design criteria for minimizing adhesion. An atomistic model of ice-copper interaction is constructed based on electronic structure calculations and used to show that reasonable molecular geometry and binding energy at the interface can be obtained. Through molecular dynamics simulations we find that the ice layer adjacent to the copper surface is structurally more disordered than the layers further away, a result which is verified by the Raman spectra of vibrational frequencies. The primary adhesive bond is made by the adsorption of oxygen atoms at the lattice sites of the metal substrate. The information obtained by Raman spectroscopy and molecular dynamics is then exploited to arrive at specific recommendations for designing polymeric deicing coatings and materials. 相似文献
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Qingteng Zhang Eric M. Dufresne Alec R. Sandy 《Current Opinion in Solid State & Materials Science》2018,22(5):202-212
Insight into the spatial ordering and dynamics of structural heterogeneity in materials is at the heart of understanding their structure and function. X-ray photon correlation spectroscopy (XPCS) measures the dynamic structure factor providing information on the spontaneous low-energy dynamics intrinsic to many materials. Combined with in situ and in operando capabilities, XPCS provides unique insight into a variety of scientific areas, including phase separation in binary alloys, aging in metallic glasses, surface dynamics during growth, domain wall dynamics in ferroic complex oxides and charge and spin density wave motion in quantum materials. This review summarizes some recent XPCS work in these areas and discusses scientific opportunities that will be made possible with the many-fold increase in coherent flux provided by the world-wide construction and commissioning of X-ray sources based on multi-bend achromat (MBA) storage ring (SR) lattices and high repetition rate free electron lasers (FELs). 相似文献
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Molecular components with their inherent scalability are expected to be promising supplements for nanoscale electronic devices. Here we report on how to specifically tune the electronic structure of chemisorbed molecules and thus to gain control of molecular transport properties. The electronic structure of our prototype π-conjugated carboxylic acid anchored on the Cu(110) surface is modified systematically by inserting nitrogen atoms in a six-membered aromatic ring, a carboxylic functional group at the aromatic ring or both. Depending on the specific nature of the substituent, the relative position of the occupied or unoccupied electronic states with respect to the Fermi level can be specifically controlled and thus the transport properties of the studied molecular systems are modified intentionally, as proven by our scanning tunneling spectroscopy measurements. On the basis of the insight gained by our systematic experiment and first-principles calculations we are also able to predict the specific molecular character (σ or π) of the orbitals involved in the transport process of a carboxylate-Cu(110) system, depending on the functionalization pattern employed. 相似文献
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Hemraj-Benny T Banerjee S Sambasivan S Balasubramanian M Fischer DA Eres G Puretzky AA Geohegan DB Lowndes DH Han W Misewich JA Wong SS 《Small (Weinheim an der Bergstrasse, Germany)》2006,2(1):26-35
We have demonstrated near-edge X-ray absorption fine structure (NEXAFS) spectroscopy as a particularly useful and effective technique for simultaneously probing the surface chemistry, surface molecular orientation, degree of order, and electronic structure of carbon nanotubes and related nanomaterials. Specifically, we employ NEXAFS in the study of single-walled carbon nanotube and multi-walled carbon nanotube powders, films, and arrays, as well as of boron nitride nanotubes. We have focused on the advantages of NEXAFS as an exciting, complementary tool to conventional microscopy and spectroscopy for providing chemical and structural information about nanoscale samples. 相似文献