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The calculating equations which could be used to obtain diad composition from the peakintensities of carbon spectra were derived. The result of the microstructure calculated from thediad compositions was in good agreement with that obtained through IR or ~1H-NMR measurement. 相似文献
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Triad sequence distributions in a series of P(AM/AA) with different AA% were calculated from copolymerization reactivity ratio r_1 and r_2 based on first order Markov statistic model, and the calculated data compared with observed ones from ~(13)C-NMR spectra showed good agreement with each other. The sequence distribution in P(AM/AA) obtained under our experimental conditions fits in with first order Markov statistic model. A significant sequence structure difference was observed between P(AM/AA) and alkaline hydrolyzed polyaerylamide, ABA triad (acrylate unit center), AAA and AAB triads (aerylamide unit center) dominated in hydrolyzed ones. 相似文献
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A ~(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites. 相似文献
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The sequence structures of emulsion-processed SBR and solution-processed (by lithium catalyst) SBR were investigated by ~(13)C-NMR spectroscopy. Seventeen peaks within unsaturated carbon region were recorded under the adopted experimental conditions. Assignments for these peaks were made by empirical-parameter-evaluation method. 相似文献
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Isoprene can be plymerized with Fe(acac)_3-phen-AlEt_3 catalyst system into a polymer mainly containg 3, 4-unit and capable of crystallizing to some extent. The ~(13)C-NMR spectra of 3, 4-polyisoprene synthesized: with Fe-catalyst system were investigated, and the: sequence distribution of cis-1, 4, trons-1, 4 and 3, 4-units and the amount of head-to-head and tail-to-tail linkages of 1, 4 and 3, 4-units were discussed. Results showed that the contents of cis-1, 4, trans-1, 4 and 3, 4-unit calculated from different carbon types were satisfactorily identical, indicating correct assignments of these peaks. 相似文献
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凝胶渗透色谱法(GPC)广泛用于测量高聚物的分子量及其分布,但即使是根据普适校准原理也需知道溶液体系的K、α值。已经提出了几种改进方法来估算分子量,其中文献[2]提出利用特性粘数和GPC谱图来估算平均分子量。后来有些学者从实验角度对此方法 相似文献
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A program of Monte Carlo simulation of binary copolymerization for E-SBR (emulsion polymn. SB rubber) was made according to the terminal model. The simulation results obtained by this program were in good agreement with those experimental ones. A detail microstructure information of E-SBR molecular chain has been provided. 相似文献
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The dynamics of a series of poly(n-alkyl methacrylates) is investigated by means of ~(13)C spin-lattice relaxation experiments. The results show that the dynamics has the polymer property dependence. 相似文献
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激光解吸/傅里叶变换质谱(Laser Desorption/Fourier Transform MassSpectrometry,LD/FTMS)技术是测定高分子低聚物(MW=1000-10000)平均分子量和分布的一种新的有效方法。采用这项技术,本文研究了一系列的均聚醚和共聚醚,得到了占主导地位的含K~+的准分子离子分布图,用自编程序处理这些数据得到的数均分子量与VPO、GPC、NMR等方法的测定值相一致。还讨论了样品制备中的碱金属盐和实验参数对测定结果的影响等问题。 相似文献
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Samples of polyphenylsilsisquioxane (PPSQ)using CaF_2 or MgF_2 as the main catalysts hadbeen prepared under different polymerization conditions. The results were treated on anorthogonal design L_9 (3~4). All weight-average molecular weights (M_W ) of PPSQ had beenmeasured by gel permeation chromatography (GPC). Effects of polymerization conditionsincluding reaction temperature, composition of the dual catalysts (CaF_2 or MgF_2 and DCC),mixture of solvents and reaction time on M_W of PPSQ have been discussed. The quantity of thecatalysts is the most important factor that affects M_W of PPSQ. Reaction temperature is thesecond important factor. Appropriate polymerization condition has been established to get PPSQwith high M_W. 相似文献
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环氧树脂/聚砜共混体系相结构的调控研究——环氧预聚物分子量的影响 总被引:9,自引:0,他引:9
研究了不同分子量的环氧预聚物对双酚A型双官能团环氧树脂 /聚砜 (PSF) /固化剂 (二氨基二苯基砜 ,DDS)体系相分离结构的影响 .通过红外光谱 (FTIR)和动态热机械分析 (TMA)对反应转化率、玻璃化温度以及固化温度的关系的研究 ,表明环氧预聚物分子量较小时 ,凝胶点和玻璃化是影响相结构的关键因素 ;环氧分子量较大时 ,环氧扩链后粘度的变化则成为抑制相分离的重要因素 .电子显微镜 (SEM)结果表明改变环氧预聚物分子量可以达到调控相结构的目的 ,随着预聚物分子量的增大 ,体系的微区尺寸减小 . 相似文献
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~(13)C-NMR chemical shifts of model compound of a novel side chain liquid crystalline polymer, poly 2.5-his (4-alkoxybenzoyloxy) styrene , have been assigned in this study. Moreover, by using high-resolution solid-state CP/MAS (cross polarization/magic angle spinning) technique, the spectrum shows that in the crystalline state the ester linkage has a conformation nearly perpendicular to the either side of ring planes, and that the alkoxy groups are not fully in zigzag form. The possible conformational changes around the mesogens from the solid state to the mesophase are discussed. 相似文献