序列分布导向的CGC催化乙烯与1-辛烯共聚过程建模

限制几何构型催化剂(constrained geometry catalyst,CGC)特别适用于乙烯与α-烯烃溶液聚合法制备高性能聚烯烃弹性体POE(polyolefin elastomer)。基于CGC催化乙烯与1-辛烯共聚反应机理,建立了乙烯与1-辛烯共聚反应动力学模型并确定了动力学参数。采用前期实验获得的乙烯消耗速率曲线与催化剂平均活性验证了动力学模型的准确性。基于动力学模型和面向序列结构的共聚机理,建立了乙烯与1-辛烯共聚过程序列分布模型。模型可准确预测序列分布与短支链含量及其随反应条件的变化趋势。结果表明,随着1-辛烯浓度的增加,乙烯序列长度逐渐减小,其平均序列长度线性降低,而1-辛烯平均序列平均长度呈线性增加的趋势。所建模型可为从聚合过程角度调控POE链结构提供理论参考。     

13C-NMR study of ethylene/1-hexene and ethylene/1-octene copolymers obtained using homogeneous catalysts

Summary This study employed the ¹³C-NMR spectroscopy to investigate the influence of the increase of the comonomer concentration on the microstruture of ethylene/1-hexene and ethylene/1-octene copolymers obtained by the use of MeSiCp₂ZrCl₂, Cp₂ZrCl₂, Et[Ind]₂ZrCl₂ and [Ind]₂ZrCl₂ catalysts. For both comonomers butyl or hexyl branches were isolated between ethylene blocks. As the -olefin concentration in the copolymer increased, butyl or hexyl branches became closer, some of them, separated by only one or two ethylene units. Incorporation of -olefin in the copolymer was higher for the bridged catalysts, MeSiCp₂ZrCl₂, and Et[Ind]₂ZrCl₂ than for the unbridged ones. The -olefin size did not seem to effect its reactivity towards ethylene.     

Investigation by carbon-13 and proton NMR spectroscopy of the diglycidyl derivative of phenolphthalein

¹³C- and ¹H-NMR studies have shown conclusively that the main component of the epoxy resin derived from phenolphthalein and epichlorohydrin is an aromatic diglycidyl ether containing a lactone ring, rather than a glycidyl ether-glycidyl ester compound containing a quinoid ring.     

Role of titania in TiO2–SiO2 mixed oxides-supported metallocene catalyst during ethylene/1-octene copolymerization

The present study showed enhanced activities of ethylene/1-octene copolymerization via TiO₂–SiO₂ mixed oxides-supported MAO with a zirconocene catalyst. It was proposed that titania was decorated on silica surface and acted as a spacer to anchor MAO to the silica support resulting in less steric hindrance and less interaction on the support surface.     

Monomer sequence characterization of propylene-1-olefin copolymers by carbon-13 NMR spectroscopy

Complete comonomer sequence assignments were made for a series of propylene-1-olefin copolymers, including 1-butene, 1-hexene, and 1-octene, to establish the effect of branch length on the sequence sensitivity of the backbone carbon chemical shifts. Particular attention was paid to the effect of branch length on the monomer sequence sensitivity of the αα carbon chemical shifts. As opposed to the ethylene-1-olefin copolymers where the reported αα carbon chemical shifts were exclusively tetrad sensitive regardless of the branch length, the αα carbons in each of the three propylene-1-olefin systems examined showed apparent tetrad, triad, and dyad monomer sequence sensitivities as the center dyad changed from PP to PX to XX where X represents the individual 1-olefin.     

乙烯四聚制1-辛烯的研究

研究了乙烯选择性四聚制1-辛烯的催化剂体系,利用氯化二苯基膦与胺反应生成二苯基膦胺配体,它与乙酰丙酮铬在助催化剂的存在下显示出较高的催化乙烯四聚的活性和较高的1-辛烯选择性;考察了不同溶剂、温度、压力、n(Al)/n(Cr)及第四组分对催化剂体系的影响,确定了适宜的条件,当n(Cr)/n(PNP)/n(Al)为1∶2∶300,反应温度为30℃,压力为3 MPa时,反应时间为30 min,进行乙烯四聚实验,催化剂活性达58.10 kg/(g·h),1-辛烯的选择性接近70%。     

The curing of an epoxy resin as followed by carbon-13 NMR spectroscopy

Variable-temperature carbon-13 NMR spectroscopy was used to examine the curing reaction of DGEBPA with piperidine. An initial adduct was directly observed and the disappearance of monomer could be conveniently followed. Unreacted epoxide carbons were detectable in cured samples.     

Dipolar-decoupled carbon-13 NMR study of highly oriented polyethylene films

Summary High-resolution solid-state ¹³C NMR spectra and ¹³C relaxation times T₁ and T₁ have been measured at 40–100° C for uniaxially oriented polyethylene films with the drawing direction parallel to the magnetic field; this sample has a unique morphological structure that the noncrystalline chains are nearly disordered irrespective of the high degree of drawing. A sharp resonance line(line A) appears at the position corresponding to the principal value ₃₃ of the chemical shift tensor for the CH₂ carbons with the trans-trans conformation. Another sharp linedine B) is observed at almost the same chemical shift as for the CH₂ carbons of polyethylene in solution. Although these observations are similar to those for a cold-drawn polyethylene sample reported previously, line B is much enhanced in intensity and the linewidth is narrower in the present sample, reflecting the disorientation of the noncrystalline component. It is found from T₁ measurements that line A contains two components with different molecular mobility, both being assigned to the crystalline components. On the other hand, the line B is composed of a single component assignable to the noncrystalline component with liquid-like molecular mobility.     

Copolymerization of ethylene and 1-octene by homogeneous and different supported metallocenic catalysts

In this work, the performance of the homogeneous catalyst system based on Et(Flu)₂ZrCl₂/MAO was evaluated on the copolymerization of ethylene and 1-octene. Characteristics of some of the produced polymers were also investigated. A study was performed to compare this system with that of Cp₂ZrCl₂/MAO. The influence of different support materials for the Cp₂ZrCl₂ was also evaluated, using silica, MgCl₂, and the zeolite sodic mordenite NaM. An increase in activity was observed in relation to the comonomer addition for the two homogeneous catalysts. The copolymers produced by the Et(Flu)₂ZrCl₂/MAO system showed higher molecular weight and narrower molecular weight distribution. We verified that the catalyst supported on SiO₂ was the most active one, although the copolymers produced with the catalyst supported on NaM showed higher molecular weight and lower molecular weight distribution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 724–730, 2001     

限定几何构型茂金属催化剂催化乙烯/1-己烯共聚研究

以自制的限定几何构型茂金属催化剂为主催化剂,甲基铝氧烷为助催化剂,对乙烯/1-己烯共聚性能进行研究,考察溶剂、Al与Zr物质的量比、聚合温度、聚合压力和共聚单体浓度等工艺条件对催化剂活性以及聚合物性能的影响。确定乙烯/1-己烯共聚合的工艺条件为:以正庚烷为溶剂,Al与Zr物质的量比为700~1 000,聚合温度(100~120)℃,聚合压力(1.2~2.0)MPa,优选1-己烯浓度为(0.8~1.8)mol·L~(-1)。     

Solubility of ethylene in 2,2,4-trimethylpentane and 1-octene mixture

With a static type equilibrium cell and the pressure decaying method, the solubility of ethylene in a mixture of 2,2,4-trimethylpentane and 1-octene was measured in the temperature range of 323.15-423.15 K, pressure range of 5-25 bar, and 1-octene concentration from 0 to 85 wt%. The experimental results show that the solubility of ethylene in a 2,2,4-trimethylpentane and 1-octane mixture increases with system pressure but decreases with system temperature.The experimental solubility data were also expressed in the vapor-liquid equilibrium relationship and correlated by the bubble pressure calculation using the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules. Among the deviations between the experimental and correlated results, the largest value of average absolute relative deviation is 1.73% for pressure at 423.15 K and that of average absolute deviation is 0.0024 mol fraction for vapor composition at 373.15 K by the Zhong-Masuoka mixing rule.     

Polymerization and characterization of ethylene/propylene and ethylene/1-octene copolymers produced with bridged Zr- and Hf-based metallocenes

Ethylene/propylene (E/P) and ethylene/1-octene (E/O) copolymers were polymerized with two bridged metallocene catalyst systems, Et(Ind)₂ZrCl₂/MAO and Et(Ind)₂HfCl₂/MAO, respectively. The copolymers produced and some commercial reference copolymers were characterized by DSC, SEC, DMA and ¹³C NMR. The Hf-catalysed E/P polymerizations showed much lower activities than the corresponding Zr-catalysed polymerizations but gave polymers with high molar mass. The Hf-based copolymers also showed two melting peaks which may be indicative of several active sites of the catalyst. A comparison of E/P copolymers, containing about 20 mol-% propylene and produced with Zr, Hf and homogeneous V-catalysts, respectively, indicated that the Hf and V-catalysts gave material more similar to each other. The E/O copolymers produced with Zr-catalysts gave very low molar masses and the reactivity ratios, calculated from the NMR data, indicated that the Hf-catalyst has a slightly higher reactivity for 1-octene and the Zr-catalyst some better reactivity for ethylene. Segregation fractionation studies by DSC indicated that a lower 1-octene feed gives more heterogeneous copolymers and the DMA measurements reveal the existence of a linear correlation between the 1-octene content and the intensity of the tan δ_max peak.     

Fully quantitative carbon-13 NMR characterization of resol phenol-formaldehyde prepolymer resins

Different resol phenol-formaldehyde prepolymer resins have been synthesized with different Formaldehyde/Phenol (F/P) ratios or different catalysts and characterized by ¹³C NMR spectroscopy in solution. A fast quantitative measuring protocol is proposed based on the use of chromium(III)acetylacetonate as a relaxation agent. APT (attached proton test) and DEPT (distortionless enhancement by polarisation transfer) spectra were acquired to enable proper resonance assignments, especially in the regions with severe signal overlap. Equations are presented in which the methylene bridges (MB), the methylol groups (MG) and the dimethylene ether bridges (DMEB) of resol resins are quantitatively taken into account. Important structural factors determined quantitatively for resol prepolymer resins are the F/P ratio after reaction, the degree of polymerization (n), the number average molecular weight (M_n) and the content of free ortho and para positions.     

POSS改性负载型Ziegler-Natta催化剂及其乙烯/1-己烯共聚反应

采用具有开放型骨架结构的大孔SiO₂（Macro-SiO₂）与MgCl₂形成复合载体,同时引入聚倍半硅氧烷（POSS）形成具有空间分隔作用的POSS/MgCl₂纳米团聚体,负载TiCl₄后制备得到改性Ziegler-Natta催化剂。采用红外分析、热重分析、CO低温吸附红外、扫描电镜、粒径分析等手段对POSS改性前后催化剂的结构进行表征,发现POSS的引入能诱导MgCl₂形成更多Mg_4c²⁺缺陷位点,并促进了Lewis酸性位点的形成,有利于TiCl₄有效活性中心的负载。乙烯/1-己烯共聚结果表明,POSS改性催化剂活性较高,最高可达1.03×10⁶ g?（mol?h）^-1,同时具有更高的共聚能力,共聚产物中共聚单体摩尔分数可达3.79%,且聚合产物具有较窄的分子量分布（MWD=3~6）。     

Application of solid state carbon-13 NMR spectroscopy to chemically modified surfaces

The nuclear magnetic resonance (NMR) techniques, high-power decoupling, magic-angle spinning, and cross polarization for high resolution in solid materials have been utilized to characterize surface-modified silicas. Solid state Carbon-13 NMR was used to study the chemical adsorption of a series of organosilane coupling agents on the silica surface. The type of information that can be obtained from such surface studies includes chemical bonding between the surface and the organosilane, the effects on steric hindrance of the hydrocarbon chains of the coupling agent, and other silane-surface interactions. The approach for the analysis involved comparing the spectra of the treated silica to the spectra of the corresponding condensed coupling agents. Spectral differences in terms of changes in chemical shifts and line widths are observed. The results are interpreted in terms of chemical bonding and structural differences of the silane coupling agents adsorbed onto the surface.     

Determination of the microstructure of acrylonitrile-butadiene and styrene-butadiene copolymers using carbon-13 NMR

Summary The microstructures of copolymers such as acrylonitrile-butadiene and styrene-butadiene are determined directly from the ¹³C NMR spectra without resorting to empirical factors. Experimental parameters were devised to overcome the difficulties due to long spin-lattice relaxation times or to different nuclear Overhauser effects.     

Improved quantitative solution state C NMR analysis of ethylene-1-octene copolymers

In order to acquire fully quantitative, high signal-to-noise ¹³C NMR spectra of ethylene-1-octene copolymers in a relatively short period of time, a detailed protocol has been developed, based on the addition of an optimised amount of the relaxation agent chromium(III)triacetylacetonate and without using nuclear overhauser enhancement (NOE). Compared to classical measurements with NOE, the proposed measuring protocol additionally offers a gain in signal-to-noise of 16%, which corresponds to a gain in experimental time of 34%. It allows precise and accurate quantification of all resonances, including small one's related to, e.g. comonomer inversion, and offers more refined information towards the determination of chemical shift and peak area measurements and the development of statistical chain microstructure models.     

Characterization of substituted phenol–formaldehyde resins using solid-state carbon-13 NMR

Crosslinked substituted phenol–formaldehyde resins were synthesized from cashew nut shell liquid, 3-n-pentadecylphenol and phenol with formaldehyde. The resulting resins were crosslinked and investigated using carbon-13 NMR in the solid state using cross-polarization, magic angle spinning, and dipolar decoupling. Comparisons were made between the spectra of pure phenol–formaldehyde resins and it was shown possible to distinguish between the resins. It was also shown that the proton-dephased spectrum gave better spectral resolution for the substituted compounds. In addition, the solids carbon-13 technique verified that the degradation of the substituted phenolic resins occurs first with the degradation of the side chain in agreement with suggestions from earlier work.     

乙烯和/或1-丁烯与丙烯共聚合的工业化研究

分析了Sphripol-Ⅱ环管工艺引入丙烯、乙烯及1-丁烯共聚单体后的聚合特性。引入乙烯后催化剂活性增加,氢调敏感性变差。引入1-丁烯后,催化剂活性变化不大,链转移速率增加,需降低H2用量以确保无规共聚PP的熔体流动速率合格。引入乙烯和1-丁烯的三元共聚合催化剂活性提高,氢调敏感性与乙烯和丙烯的二元共聚合时相当;因闪蒸线蒸汽压力的限制,装置负荷降低30%;控制环管反应器内淤浆中可溶物的含量,调整反应温度为60.0℃,乙烯质量分数≤2.5%;控制汽蒸器内温度低于105.0℃,避免低分子物料熔融黏附在汽蒸器表面及干燥器表面。