IN SITU MONITORING OF COORDINATION COPOLYMERIZATION OF BUTADIENE AND ISOPRENE VIA ATR-FTIR SPECTROSCOPY

FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance （ATR） immersion probe was utilized to study in situ the copolymerization of butadiene （Bd） and isoprene （Ip） with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated. The kinetic study of copolymerization of Bd and Ip was further conducted, and the monomer reactivity ratios were determined via in situ ATR FTIR. The signal band at 1010 cm^-1 was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration （[Bd]） in the range of 0.46-3.88 mol.L^-1. The signal bands at 890 and 989 cm^-1 were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration （[Ip]） in the range of 0.08-4.73 mol·L^-1 at 890 cm^-1 and 0.08-7.49 mol·L^-1 at 989 cm^-1, respectively. Thus the signal band at 1010 cm^-1 was chosen to monitor Bd concentration and bands at 989 and 890 cm^-1 to monitor Ip concentration during the copolymerization, respectively. It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically. The poiymerization rates were first order with respect to both [Bd] and [Ip], respectively at different polymerization temperatures. The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol^-1 and 57.7 kJ·mol^-1, respectively. The monomer reactivity ratios were calculated to be 1.08 for Bd （rBd） and 0.48 for IP （rIp） based on FTIR data. The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.

Enhanced Interfacial Adhesion in HDPE/HA Composites by Surface Modification of HA Particles via in situ Polymerization and Copolymerization

Hydroxyapatite （ HA ）- reinforced high density polyethylene （HDPE） was developed as a bone replacement material,In order to enhaace the interfacial bonding between HA and polyethylene and improve the mechanical properties of HDPE/ HA composites, the surface of the micron-sized HA particles was modified by in situ polymerization of butyl acrylate （ BA ） and in situ copolymerization of vinyl triethoxyl silane （ VTES ） and BA , then the modifwd HA particles were compounded with HDPE. The effects of the surface modification of HA on morphology and mechanical properties of HDPE/ HA composites were investigated. The experimental results show that the presence of HA particles does tuft inhibit the polymerization of BA . The poly（ butyl acrylate） （ PBA ） segments on the HA surface enhance the compatibility between HA and HDPE, improve the dispersion of HA particles in HDPE matrix, and enhance the interfacial adhesion between HA and matrix. Surface modifieations , especially by in situ copolymerization of VTES and BA, significantly increase notch impact strengths and marginal stiffness and tensile strengths of HDPE/HA composites. And it is found that there is a critical thickness of PBA coating on HA panicles for optimum mechanical properties of HDPE / HA composites.

<i>In Situ</i>UV–Vis Spectroelectrochemical Studies on the Copolymerization of Diphenylamine and <i>o</i>-Phenylenediamine

The in situ ultraviolet-visible (UV-Vis) spectroelectrochemical study on the copolymerization of diphenylamine (DPA) and o-phenylenediamine (OPD) has been performed at a constant potential of 0.8 V using indium tin oxide (ITO)-coated glass electrodes as working electrode. And also, as a comparison, the electrochemical homopolymerizations of DPA and OPD have been investigated by using the in situ spectroelectrochemical technique. The intermediate species generated during the electrochemical homopoly-merization of DPA and OPD, and the copolymerization of DPA with OPD have been identified by using the in situ spectroelectrochemical procedure. The results reveal the formation of an intermediate in the initial stage of copolymerization through the cross-reaction of the cation radicals of DPA and OPD, and the absorption peak located at 538 nm in the UV–Vis spectra is assigned to this intermediate. To further investigate the copolymerization of DPA with OPD, cyclic voltammetry (CV) has been used to study the electrochemical homopolymerization of DPA and OPD and also the copolymerization of DPA and OPD with different concentration ratios in solution. The different voltammetric characteristics between the homopolymerization and copolymerization processes exhibit the occurrence of the copolymerization, and the difference between the copolymerization of DPA and OPD with different concentration ratios shows the dependence of the copoly-merization on the concentrations of DPA and OPD. The copolymer has also been characterized by Fourier transform infrared spectroscopy (FT-IR).

Preparation of Poly ( L-lactic acid ) / Vermiculites Composites by in situ Copolymerization of Lactic Acid and Hydroxylic Vermiculites

L-lactic acid (L-LA) based copolymer/hydroxylation vermiculites composites (PLLA-co-bis A/HVMTs) were prepared by in situ reaction among L-LA, adipic acid, and hydroxylation lamellar vermiculites (HVMTs) using bisphenol-A epoxy resin as chain extending agent. HVMTs were obtained by sulfuric acid-leaching of lamellar vermiculites (VMTs). The effects of sulfuric acid leaching on the VMTs structure were characterized by X-ray diffraction (XRD), 29Si magic-angle spinning nuclear magnetic resonance(29Si NMR), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). FTIR, FE-SEM, and TGA were used to characterize the reaction activity of HVMTs. The results indicated that VMTs with increased hydroxyl groups had been successfully obtained and could react with -COOH of the reaction system. The amount of L-LA based copolymer grafted on the surface of HVMTs was more than 22%. The onset decomposition temperature of L-LA based copolymer grafted on the surface of HVMTs was 30℃ higher than that of free L-LA based copolymer.

Researches on the In Situ Copolymerization of Ethylene with Catalysts Immobilized onto the Molecular Sieves

In this paper,the bi-functional catalyst system composed of molecular sieve（MCM-41） immobilized oligomerization catalyst（C25H17Cl2N3·FeCl2） and copolymerization catalyst（Et（Ind）2ZrCl2） was employed in the in situ copolymerization of ethylene aiming to prepare the Linear low density polyethylene（LLDPE）.In this paper,we mainly argued the regular pattern of the in situ copolymerization of ethylene in limited nano-space and compared it with that happening in free space.The impact of variance of the reaction temperature,Fe/Zr value and the A1/（Fe＋Zr） value on the activity of the in situ copolymerization of ethylene has also been introduced.Furthermore,the degree of branching,thermal properties and crystalline changes of the obtained polymerization products prepared from different reactivity were investigated.

COPOLYMERIZATION OF ETHYLENE WITH 1-OCTENE USING Et(Ind)_2ZrCl_2/MAO CATALYST

Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalystsystem. The effect of temperature and zirconium aluminum mole ratio of the catalyst onthe copolymerization was also investigated. The results of ^(13)C NMR determination of thecopolymer showed that the 1-octene units in the copolymer are principally isolated.

Copolymerization of Ethylene/1-Butene with Heterogeneous TiCl4/(α-Diimine)nickel(Ⅱ) Complex Combined Catalyst

The new type heterogeneous combined catalyst system TiCl4-(α-diimine)nickel(Ⅱ) complexes/MgCl2-SiO2/AlR3 was prepared. Ethylene and 1-butene were copolymerized with the catalysts in slurry phase. It was found that with combined catalyst, the copolymers with lower density and higher branched degree were obtained. 13CNMR results showed that in the obtained copolymers existed not only ethyl but also some other kinds of branches due to the fact that ethylene exhibits the behavior of oligomerization and copolymerization in-situ with combined catalysts.

后过渡金属铁系催化剂与Et[Ind]_2ZrCl_2复配催化乙烯原位共聚中的“共单体效应”

研究了以{2-[2-MeC6H4N=C(Me)]2C5H3N}FeCl2为齐聚催化剂、以Et[Ind]2ZrCl2为共聚催化剂复配,在甲基铝氧烷作用下催化乙烯原位共聚的“共单体效应”。在n(Al)/n(Zr)、n(Al)/n(Fe)和n(Al)/n(Fe+Zr)分别为2000时,改变齐聚催化剂/共聚催化剂的配比,均观察到共单体效应。探讨了助催化剂用量、主催化剂用量和聚合温度对共单体效应的影响。助催化剂用量的增加使出现最佳活性点的n(Fe)/n(Zr)发生了前移,而主催化剂用量的增加使出现最佳活性点的n(Fe)/n(Zr)发生了后移。聚合温度的改变使共单体效应的变化规律发生了改变。

Preparation and Mechanical Properties of HIPS Composites Containing PS-grafted-hydroxyapatite Particles

The surfaces of the micron- sized HA particles were modified by in situ copolymerization of vinyl triethoxyl silane （VIES） and styrene （ St ）. Then, the modified HA particles were compounded with HIPS. The results showed that the polystyrene （PS） macromolecules were grafted on the surfaces of HA particles during in situ copolymerization of VIES and St. Thereby, PS chains grafted on the HA surface enhance the compatibility between HA and HIPS, improve the dispersion of HA particles in HIPS matrix, and enhance the interfacial adhesion between HA and matrix. The stiffness, tensile strength and notch impact strength of HIPS/HA composites are improved at the same time. And there is a critical coating thickness of PS to the HA surface for the optimum mechani- cal properties of HIPS/HA composites.

SYNTHESIS OF BRANCHED POLYETHYLENE USING (α-DIIMINE)NICKEL(Ⅱ)TiCl_4 COMBINED AND SUPPORTED CATALYST

Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3 ) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCl 4 , the molar ratio of NiL to TiCl 4 , cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and 13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.

Magnesium hydroxide whisker modified via in situ copolymerization of n-butyl acrylate and maleic anhydride

Magnesium hydroxide(MH) whiskers were modified via in situ polymerization of n-butyl acrylate and maleic anhydride. Sodium dodecyl sulfonate was used as emulsifier. The modifying effect was evaluated by using contact angle and activation index. The thermal stability,functional groups, structure, morphology, phase composition and surface element valence of MH whiskers were characterized by thermogravimetry-differential scanning calorimetry(TG-DSC), Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). Results reveal that the contact angle and activation index of modified MH whiskers are 105°and 76.5%, the thermal stability shows little change, and the decomposition temperature ranges between 38 and419 ℃. The copolymer of n-butyl acrylate and maleic anhydride absorbed on the surface of MH whiskers leads to the increased diameter and makes the surface of whiskers be rougher. Furthermore, the absorption of element C on the surface of MH whiskers increases, and the diffraction intensity of C 1 s spectra increases; thus, the compatibility of whiskers in the organic phase can be improved significantly. Lastly, the surface molecular model of MH whiskers modified via in situ copolymerization of n-butyl acrylate and maleic anhydride is established.

Preparation of PE/MMT nanocomposite by monomer intercalation and in situ copolymerization

The catalyst {[(2-ArN=C(Me))2C5H3N]FeCl3} (Ar = 2-C6H4(i-Pr)) with methylaluminoxane (MAO) as co-catalyst was intercalated between layers of montmorillonite (MMT) for ethylene oligomerization. Metallocene catalyst Me2Si(Ind)2ZrCl2 and MAO was then added to form a dual functional catalytic system. A PE/MMT nanocomposite was prepared by copolymerization of ethylene with α-olefins produced in situ from ethylene over the dual functional catalytic system. The catalytic system was of high polymeric activity. The resultant PE/MMT nanocomposites were stable and got increases in tensile strength and temperature of maximum weight loss (Tonset).

Investigation on chain structure of LLDPE obtained by ethylene in-situ copolymerization with DSC and XRD

Thermal segregations of LLDPE were treated with successive self-nucleation/annealing (SSA) on dif-ferential scanning calorimetry (DSC). Information on molecular heterogeneity of LLDPE was obtained. After SSA was treated, the multiple endothermic peaks were observed in the DSC thermograms during heating experiment. It is obtained that the thickness of different lamellas formed by segments of vari-ous lengths was 4―10 nm. X-ray diffraction (XRD) results showed that the crystallites dimensions of various reflections were about several dozens of nanometers. The ethylene/α-olefin copolymers and the copolymer via in-situ copolymerization were similar to each other for molecular heterogeneity and XRD characteristics, which revealed that it was possible to use the ethylene/α-olefin copolymers to simulate the copolymer via in-situ copolymerization of ethylene to simplify the complexity of the structure of the ethylene in-situ copolymer.

苯乙烯—马来酸酐原位共聚包覆铝颜料的研究

研究了苯乙烯—马来酸酐原位共聚包覆铝颜料的最佳反应条件,探讨了m(St+MAn)/m(Al)对颜料铝粉耐腐蚀性能与光泽度的影响。结果表明,最佳反应条件是:反应温度为80℃;反应时间为4h;引发剂用量为0.075g;n(St)∶n(MAn)为1∶1。当m(St+MAn)/m(Al)为0.1时,包覆得到的产物同时具有良好的光泽度与耐腐蚀性。运用IR、光学显微镜、SEM、粒度分析等手段对包覆样品进行了分析与表征。

蒙脱土负载聚合催化剂用于乙烯原位共聚制备LLDPE

将蒙脱土 (MMT)负载的聚合催化剂rac Et(Ind) 2 ZrCl2 和均相低聚催化剂 { [(2 ArNC(Me) ) 2 C5H3N]FeCl2 } (Ar=2 ,4 C6 H4 (Me) 2 )组成双功能催化体系用于乙烯原位共聚制备线性低密度聚乙烯 (LLDPE) .通过调节两种催化剂之间的比例和MAO的用量制备了一系列支化度不同的LLDPE产品 .聚合反应动力学曲线表明 ,两种催化剂表现出各自的乙烯吸收特征 ,蒙脱土负载化的共聚催化剂催化乙烯聚合时反应平稳易控制 .DSC曲线表明 ,聚合物的熔点和结晶度随Fe Zr的增大而减小 .用密度梯度法测得的聚合物密度随Fe Zr的增大而降低 .从1 3C NMR谱图上可以看到 ,得到的聚合物是LLDPE ,其支化度随Fe Zr的增大而增大 ,聚合物中仍含有未共聚的α 烯烃 ,这一点从GPC上也能得到验证 .扫描电镜 (SEM)

负载型钴二亚胺配合物-TiCl_4复合催化剂制备新型乙烯/1-丁烯共聚产物结构性能研究

合成了三种负载型二亚胺配体钴配合物 TiCl4复合催化剂 (CL1、CL2、CL3催化剂 ) .不用MAO ,以烷基铝为助催化剂 ,用它们催化乙烯 1 丁烯淤浆共聚合制备一系列塑性体和弹性体共聚物 .研究表明 ,复合催化剂性质受二亚胺配体性质影响 ,配体L1制备的复合催化剂具有低聚及原位共聚性能 ,可制得高支化度(36 0～ 6 1 5branchnumber 10 0 0C)低密度和极低密度 (0 885～ 0 910g cm3)塑性体和弹性体共聚物 .在 1 丁烯用量低于 5 %时 ,CL1催化剂制备的共聚产物中 1

聚丙烯合金技术的研究进展

从提高聚丙烯低温韧性和抗张强度的技术方面进行了综述,介绍了近年来采用原位技术制备聚丙烯合金各种工艺的研究进展;描述了聚丙烯合金催化剂的发展历程;指出将Ziegler-Natta催化剂与茂金属催化剂有效结合制备聚丙烯合金是未来的研究方向和发展趋势。

氯化原位接枝反应制备羟基官能化CPE——结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.

新型TiCl_4/Ni(acac)_2复合催化剂乙烯聚合反应

制备了 Ti Cl4/ Ni(acac) 2 / Mg Cl2 -Si O2 -Zn Cl2 / Al R3复合催化剂 .研究了促进剂四氯化硅 (Si Cl4)和各种聚合条件对乙烯聚合的影响及其表观聚合动力学 .用 DSC、IR、1 3C NMR对聚合产物进行了结构性能的分析和表征 .结果表明 ,促进剂 Si Cl4有很好的提高催化效率的作用 ;Ti Cl4/ Ni(acac) 2 复合催化剂有催化乙烯齐聚和原位共聚功能 ,获得了熔点和结晶度较低的、有一定支化度的中、低密度聚乙烯 .

气相法聚乙烯工艺技术及其催化剂进展

气相法工艺制备聚乙烯是当今聚乙烯工业的主要发展趋势。介绍了冷凝及超冷凝技术、不造粒技术、共聚技术、原位技术、反应器新配置、双峰技术、激光催化等聚乙烯生产新技术的开发应用情况,以及用于乙烯气相聚合的铬基催化剂、齐格勒-纳塔催化剂、茂金属催化剂等催化剂的发展历程和现状。