最新刊期
卷 ， 期 2 ， 1991
- 摘要：Polymerization of isoprene in the presence of (NdCl3+FeCl3) n Phen HAl-(i-Bu)2 was studied. The results indicate that the catalytic activity and the microstructure of polymer obtained changed greatly with changing Nd/Fe ratio in the mixed catalyst. When the content of Fe changes in the range of 0-100%, the corresponding cis-1,4 and 3,4 contents of the polyisoprene vary in the range of 94.4-22.1% and 5.6-77.9%, respectively. The catalytic activity and the polymer microstructure are influenced by Al/M ratio, concentration of mono-mer andpolymerization temperature. In the polymerization system,there are two kinds of active centers having higher catalytic activity for isoprene polymerization.
- 2
- |
- 8
- |
- 3
发布时间：2021-03-19 - 摘要：Samples of iPP and their blends with LDPE had been observed by SEM. The samples were prepared by different methods, including deep or slight etching, heat treatment, ageing by UV, heat and oxygen, and so on.Some new opinions about morphology and cause of β-spherulites had been suggested. The formation of cores of β-spherulites perhaps related to the polar force, the crystalline lamellas of β-spherulites are wide and thick, and at a distance, while lamellar bunchs take the shapes of horn or cabbage, giowing from the core under ex-tending force. The lamellar surfaces are mainly smooth and some are waveform,but are not spiral at all. In the violent ageing samples,there are some short andheavy-section cry-stalline bands.
- 39
- |
- 10
- |
- 7
发布时间：2021-03-19 - 摘要：The structure and properties of commercial ethylene-propylene block copolymers have been studied by a series of techniques. The results obtained show that the ethylene-propylene block copolymers may be a mixture of PP, PP-b-EPR, EPR and PE, and the thermal properties of the ethylene-propylene block copolymers are influenced by the random copolymeriza-tion of ethene with residual propene in the sequential copolymerization process. Meanwhile, the multi-phase structure of ethylene-propylene block copolymers was revealed by DMA and SEM.
- 5
- |
- 12
- |
- 4
发布时间：2021-03-19 - 摘要：The present work is to investigate the effect of annealing temperature Tan on microst-ructure and superstructure of HEPP fibers by FRS-XRSA and SAXS. The results show that: FRS-XRSA is a new reasonable method for studying the preferred orientation polymers, It was found that as Tan increases, the melting-crystallization-remelting-processes approach a dynamic equilibrium and the twisted lamellae, which is different from previous literatures, works, extends gradually; long periodicity increases linearly and the lamellae thickness in-creases suddenly from Tan=110 to 120℃The superatructure oflamellae consists of two-layer crystallites.Tan effects on the microstrucrure and superstructure of HEPP fibers. are greater than tan effects.
- 3
- |
- 9
- |
- 6
发布时间：2021-03-19 - 摘要：A series of main chain type aromatic copolyesters with X-shaped and rod-shaped meso-gens were synthsized by solution polycondensations. All samples were thermotropic and the liquid-crystalline behaviour of the copolyesters was studied.
- 3
- |
- 8
- |
- 11
发布时间：2021-03-19 - 摘要：Vinyl acetate was copolymerized with triallyl isocyanurate which was then saponified, activated, and DNA was immobilized on to the adsorbent. The physical properties and blood compatibility of the adsorbents were determined. Results showed that the copolymers possessed large average pore size and after saponification the hydrophilicity of the copolymer was increased, followed by the activatio the surface area of the copolymer was increased, and the pore distribution was homogenized. The adsorbent showed good blood compatibility. Platelet depletion was about 10% and no destruction of leucocyte was observed. Up to 60% of the an-DNA (0.714mg/ml,20ml was used) was removed by 1g of adsorbent,during 2h of adsorp-tion in vitro.
- 41
- |
- 8
- |
- 4
发布时间：2021-03-19 - 摘要：Up to now, on Cossee's mechanism, the stable configuration of catalytical centre, the essence of propylene coordination, the process of chain propagation, effect of alkyl aluminim and even whether Cossee's mechanismis resonale or not have still not come to identical understanding. In present paper, a theoritical study of the mechanism of propylene polymerization with Ziegler-Natta catalyst has been investigated in terms of the ASED-MO method. Acoording to Cossee's model, the calculated results are basically in agreement with the experimental,so it can be considered to be rational. Moreover,there is need tofurther investigate the related key reactions to clarify the details of mechanism. It isshown that the stable configuration of ca-talytical centre is a trigonal bipyrimid andit is activated by coordinating ofpropylene mole-cule,to be r\transformedinto a octahedron. It is just a weak coordinated bond linked pro-pylene and Ti3+ in active species has not effect ofback-donated electrons. But coordinating propylene can change the charge distribution ofsystem to facilitate the polymer chain propaga-tion. The average activation energy of polymerization calculated is 59.2KJ.Mol-1.For some disputed proplems,explainations are also given.
- 2
- |
- 8
- |
- 1
发布时间：2021-03-19 - 摘要：The kinetics of polymerization of PO and ECH using rare earth coordination catalyst composed of Neodynium 2-Ethylhexyl Phosphonatestriisobutyl Aluminum-water in toluene have been studied by a dilatometer method. It has been shown that the rate of polymerization is first order with respect to both monomer and catalyst concentrations. According to Arrhenius equation, it was found that polymerization activstion energies for PO and ECH are 61.3 Kj/mol and 48.9 Kj/mol respectively. Under the same conditions, propylene oxide polymerization proceeded fasfer than ECH polymerization. Al/Nd molar ration and H2O/Al molar ratio also have some effects on the polymerization rate,and the same is catalyst composition. The activity sequence for different rare earth element catalyst systems decresses in the following order:Nd>La>Dy>Yb>Eu;activity se-quence of catalysts containing different ligands decreases in the order: acac>P204>P507>naph; and the activity of Al(i-Bu)3 system is higher than that of catalyst with AlEt3.
- 36
- |
- 7
- |
- 4
发布时间：2021-03-19 - 摘要：The skin-core structures of three kind of injection-molded isotactic polypropylene samples were studied by X-ray diffraction. The bend, tensile and impact properties were also measured. The results show that Sample A, without nucleating agent, contains mainly a-form and has lower crystallinity and β-form crystal amount (kβ-value) in the skin than in the core. Sample β, with a-nucleating agent, only contains α-form. But Sample C, with β-nucleating agent, contains mainly β-form and has higher crystallinity and kβ-value in the skin. The mo-dification transition between a-and β-forms occurs inthe sections of Sample A and Sample C. The differences of a-and β-forms in mechanical behaviors are explained with ther struc-ture features.
- 7
- |
- 10
- |
- 6
发布时间：2021-03-19 - 摘要：Poly (tetramethylene succinate) (PTS-4,4) is synthesized from dimethyl succinate and bu-tanediol and solid polymeric electrolytes are made by dissolving lithium perchlorate in the polyester. The complexation between ions and oxygens of ester groups is found with FT-IR, NMR, and XPS techniques. The analytical results of WAXD and DSC show that PTS-4,4-LiClO4 complexes have the same crystallites as PTS-4, 4. LiClO4 mainly dissolves in the amorphous region of the polymer. The dissolution of the salt depresses the melting temperature,the crystallization degree and rate,but raises the glass transition temperature of PTS-4,4.The relation of the melting temperature and salt content of the electrolytes corresponds with Flory-Huggins theory within lower salt concentration. The ionic conductivity of PTS-2,2-LiClO4 complexes varies with the salt concentration and there is a maximum. Particularly,the loga-tion. The conductive behaviorof PTS-4,4-LiClO4 complexes could not simply be explained by Arrhenius or WLF equation. The conductive equation is inferred from diffusion theory and the process of ion migration inpolyester is described in this article.
- 35
- |
- 10
- |
- 2
发布时间：2021-03-19 - 摘要：A series of thermotropic liquid crystal aromatic copolyesters with different length of flexible chain spacer have been investigated by FTIR. The result suggests that the interaction between the mesogenic cores is dominant in forming the mesophase, while the interaction between flexible chain spacers is very weak. It is concluded that the polymethylene is in full extended trans conformation both in the crystalline and in the liquid crystalline phases when the spacer units are longer than 8. Molecular chain order parameters are also evaluated from the band dichroism. The degree of the chain orientation decreases with increase of the length of the flexible chain spacer.
- 32
- |
- 7
- |
- 1
发布时间：2021-03-19 - 摘要：Crosslinked poly-4-vinylpyridine quaternized with methyl iodide, ethyl bromide has been prepared and the quaternary salts have been used for the support of the Pd catalyst. It is found that the hydrogenation rate of poly-4-vinylpyridine quaternized with methyl iodide and complexed with Pd depends pricipally on the degree of quaternization of the support. The activity increases as the quaternization degree decreases. When the quaternization degree is less than 80%, the catalytic activity of Pd supported on poly-4-vinylpyridine quaternized with methyl iodide is larger than that of Pd supported on poly-4-vinylpyridine. The preparation condition of the catalyst has also been investigated.
- 2
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：The effects of four anilides with different structures, e. g. 4-methoxysuccinyl aniline (MSA), 4-methoxysuccinyl-p-toluidine (MST), succinic acid mono-p-toluidide (SAMT) and 4-methoxymaleoyl-p-toluidine (MMT), on the polymerization of AAM initiated with eerie ion have been studied. The overall activation energy of polymerization and the kinetic equation of polymerization were determined. The end group analysis of polyacrylonitrile by IR spectrum confirmed that the free radical produced by the reaction of MST and ceric ion could initiate the polymerization of vinyl monomer.
- 2
- |
- 8
- |
- 2
发布时间：2021-03-19
Research Article
- 摘要：Using three different compounds (1-methoxy-2-methyl-1-trimethylsiloxy propene, ethyl 3-ethoxy-3-trimethylsiloxy acrylate and ethyl 2-butyl-3-ethoxy-3-trimethyl-siloxy acrylate) as initiator and Et4 NHF2 as catalyst the initiation activity of some group transfer polymerization (GTP) monomers was compared. The results show that acrylonitrile has highest initiation activity and methacrylate monomers have lowest initiation activity. It is also reported that selective GTP of MA and MMA can be carried out by using ETSA initiator.
- 32
- |
- 7
- |
- 4
发布时间：2021-03-19 - 摘要：Radiation-induced crosslinking of poly (methyl methacrylate) (PMMA)-poly (ethylene oxide) (PEO) blend were studied. It was found that PMMA in the PMMA-PEO blend can be crosslinked in the ranges of certain dose (1-20×104Gy) and composition (PMMA%=40-75) under the absence of oxygen. Moreover, it was also found that the crosslinking degree of PMMA in the blend in which content of PMMA is 70% is the largest. The crosslinking degree of PMMA in the blend is in close relationship with the polymer compatibility.The crosslink-ing degree of the blend prepared at 60℃ is much higher than that at 25℃ .
- 4
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Graft copolymers with polystyrene backbone and poly (methyl methacrylate) branchs were synthesized via three steps: (1) free-radical copolymerization of styrene and desired amount of 2-vinylfluorene, (2) metallation of the fluorene units in the copolymers, (3) anionic graft polymerization of MMA initiated by the carbanion sites at the fluorene units. GPC measurements have proved that almost no homopolymers remain in the products. The molecular weights of the copolymers, backbones and branchs and the number of the branchs on each backbone have been determined directly or calculated.
- 6
- |
- 10
- |
- 2
发布时间：2021-03-19 - 摘要：p-Chloromethyl styrene (p-CMS) is a new industrial monomer and is attractive for both science and industry. In this paper, many important physicochemical data including IR, UV, 1H-NMR, 13C-NMR, MS of the monomer and TGA, solubility parameter of the polymer are shown. On the basis of explored kinetic results, the equation Rp= K[AIBN]0.5[ p-CMS]1.5 is proposed to express the initial overall rate of the polymerization of p-CMS in the presence of AIBN as an initiator. In the light of the results from TGA, an inference that the thermodegra-dation seems to be the main reaction during the thermal decomposition of poly-p-CMS in nitro-gen is given.
- 2
- |
- 8
- |
- 1
发布时间：2021-03-19 - 摘要：The mechanism of photosensitized decomposition of benzoyl peroxide by several anthracene derivatives has been studied. It comfirms that the photosensitized process is carried out by electron transfer.It is discovered that benzoyl peroxide can be decomposed by sensitizer of different anthracene derivatives which are used either electron donor or acceptor and the active radical which produces in this reaction can initiate the polymerization of MMA. It is considered that the BPO with positive charge in the charge transfer complex is easier to decompose into radical than that with negative charge,so the rate (Rp) of polymerzation of MMA in-itiated by the system of DCA/BPO has higher value than others.
- 3
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Photopolymerization of acrylonitrile (AN) sensitized by binary component initiators consisting of 8-acryloyloxyquinoline (AQ) and its polymer (PAQ) with carbon tetrabromide (CTB) are investigated kinetically. It is found that the polymerization rates are proportional to 0.19th power of AQ concentration, 0.35th power of CTB concentration and 0.62th power of AN concentration for AQ-CTB system initiation system; proportional to 0.24th power of PAQ concentration, 0.22th power of CTB concentration and 1.0th power of AN concentration initia-ted by above systems are obtained to be 5.26Kcal/mol and 6.34Kcal/mol respectively. It is also found that the polymerization rates sensitized by addition of CTB to AQ or PAQ are much higher than that ofAQ or PAQ alone. Forom the fluorescence analysis of AN polymers,it is confirmed that AQ or PAQ joints into the AN polymer chains. The molecular weight of PAN sensitized by the binary initiatorsystems is lower than that of AQ or PAQ sensitized.
- 27
- |
- 7
- |
- 1
发布时间：2021-03-19
Research Bulletin
- Postal code：100190
- Tel：010-62588927 Email：gfzxb@iccas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备05002797号-8
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0