最新刊期
卷 ， 期 6 ， 1991
- 摘要：Two kinds of liquid crystalline copolymers, based on p-hydroxybenzoic acid, terephthalic acid and diphenols, with regular or irregular sequence structure were synthesized by melt transe-sterification or Schottern-Baumann polycondensation. Polarizing microscope, DSC and X-ray diffraction were applied to investigate influence of sequence structure on mesogen, phase transition and solid structure of the polymers. It was found that sequence structure of liquid crystalline copolyesters has a strong influence on phase transition.Generally melting temperature of irregular copolyesters is depressed compared with their regular isomers,While the typeof mesogen remains unchanged,both are thermotropic nematic phase. The solid structure of the copolyesters can be explained on thebasis of structurl unit similarity.
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发布时间：2021-03-19 - 摘要：Several experiments were desighned to reveeal the reaction mechanism of phenolphthalein during its condensating with DCDPS in presence of potassium carbonate. The results show that the special stereo-structure derived from phenolphthalein's cardo group and its phenol rings makes it possible to form an intermediate complex between the solid potassium carbonate and phenolphthalein, which was proved to benifie to the solvation of solid potassium carbonate, the formation of the phenoxide, and to the further nucleophilic substitution reaction. It is also confirmed that the phenoxides'structures formed in potassium carbonate system are different from that formed inpotassium hydroxide system.Based on our series experimental results,a new reaction mechnism was proposed.
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发布时间：2021-03-19 - 摘要：Fourteen MC nylons (polycaprolactam) modified by three aromatic compounds containing quinoxaline ring were prepared. Their morphology, impact strength, water absorbency and melting behaviour were characterized. The introduction of the mono-model compound of poly-phenylquinoxaline(PPQ) has little effect on the crystallization of MC nylon. The addition of small amounts of phenazine (0.005-5.0%) induced a great change of color, morphology and properties of MC nylon. The modification effect was considered to result from the bydrogen bond between nylon-6 and phenazine. The effect of the di-model compund of PPQ on MC nylon is between that of he mono-model compound and phenazine.
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发布时间：2021-03-19 - 摘要：A set of poly(ethylene oxide)-poly(dimethylsiloxane)-poly(ethylene oxide) triblock copo-lymers having different block lengths in aqueous solution was stulied by small angle X-ray scattering (SAXS) method. It is shown that the amphiphilic triblock copolymers behave as lyotropoic liquid crystals in concentrated water solution. The respective influences of water concentration, block length on the geometrical parmeters of the supermolecular structures are established. The experimental results can be explained by simple geomerical model.
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发布时间：2021-03-19 - 摘要：Three specimens from solution cast polyvinyl chloride (PVC) films, one being ice-water quenched from 120℃(Q), one being slowly cooled from 120℃ (SC) and one being quenched and sub-Tg, annealed at 72℃ for 48h (AN), have been studied by infrared difference spectra Q-SC and AN-Q and temperature difference spectra of T2-T1 for every 4℃ step on heating to 120℃ at 2℃/min. SC and AN showed more trans conformers than Q. It means that the PVC chain has more gauche conformers at higher temperatures and some of these are frozen during quenching through Tg The temperature difference spectra on heating through Tg showed that the conformation changes in Q are gradual while a rather abrupt change occurs in AN at 92-88℃。A kind of chain entanglement mechanism is suggested which hinders the molecular conformation changes in AN below Tg until a sudden release occurs at Tg.
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发布时间：2021-03-19 - 摘要：Copolymerization of styrene and a-methylstyrene initiated by n-butyllithium in cyclohe-xane with tetrahydrofuran as a polar solvent has been performed. Through the investigation of copolymer composition and active species, the copolymer composition equation which applies in this system was derived based on the mechanism. The apparent reactivity ratios of two monomers were obtained. The effect of tetrahydrofuran concentration on the apparent reactivity ratios of monomers was discussed.
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发布时间：2021-03-19 - 摘要：The effect of molecular weight on dynamical process of spinodal phase separation of po-lystylene(PS) with carboxylated poly(2,6-dimethyl phenylene oxide) (C-PPO) has been investigated by using time resolved light scattering technique. In the early stage, the effect of molecular weight on dynamical parameters of phase separation, such as the growth rate, R(q) of phase se paration and apparent diffusion coefficient, are distinct, As the molecular weight increasing, the apparent diffusion coefficient, Dapp,decreases. Experimental results obtained from three mixtures tend to support the relationship of q2m/Dapp proportional to the degree of po-lymerization (N),and the diffusion behaviour coincides the reptation mechanism.
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发布时间：2021-03-19 - 摘要：Computer method for the peak separation of data on X-ray crystalline diffraction and amorphous scattering of semicrystalline polymers at low angle range(20<50°), is extended through wide angle range(20:5-140°) of X-ray diffraction-scattering by PET films. By comparing characteristic paramters of the separated most prominent amorphous peaks due to in-tersegmental scattering, the changes of the moTecular orientation at amorohous regions during PET film formation have been discussed.
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发布时间：2021-03-19 - 摘要：In this work, the action mechanism of N-ethyl-N'-phenylpiperazine-one of components in the photo-initiation system has been studied. It was found that the titled amine in which although dimethyl aniline and triethyl amine both were contained, possesses less efficiency of photoinitiation while it was composed with ketone as an initiated system. This phenomenon was discussed and the mechanism was further comfirmed by the addition of acid for promoting of photoinitiated efficiency by the quaternary ammoniation of one of amines in piperazine.
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发布时间：2021-03-19 - 摘要：Several porous and highly crosslinked resins with moderate polarity were synthesized by the suspension copolymerization of divinylbenzene respectively with methyl methacrylate, methyl acrylate, dimethyl maleate, allyl acetate, acrylonitrile, vinyl methyl ketone, and N-vinyl pyrrolidone. The resins were characterized and their capacities in adsorbing gypenosides were then determined by HPLC method. The results showed that the polarities of these resins had an important influence on their physical structures and adsorbing capacities.
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发布时间：2021-03-19 - 摘要：In the present work, the relationship between sol fraction (s) and radiation dose (R) in radiation crosslinking of PP/HDPE blends was studied. The results indicate that both Charles-by-pinner expression and Chen-Liu-Tang expression, which were well applicable with radiation crosslinking of some polymers, do not well fit to the case of PP/HDPE blends.According to Zhang's assumption, which deals with relationship between structure and radiation crosslinking of pure polymers and applies to most cases, fracture density of polymer is proportional to Rβ,where β is a parameter depending on the structure of a polymer.In this paper,we extended their assumption to polymer blends,but the Rβ value of blends were modified by equation Rβ=∑fiRβi,where fi and βi are weight fraction and β value of i component in blend,respectively. Using the modified Rβ,good linear relation between R(s+s)and Rβ of PP/HDPE blends was obtained.
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发布时间：2021-03-19 - 摘要：In this paper, the properties of ion-exchange membrane prepared by irradiating poly(sty-rene-butadiene-4-vinylpyridine) triblock copolymer, with different sulfonating agents and qoa-ternizing agents were investigated. The results showed that the ion-exchange capacity of membrane sulfonated by chlorsulfonic acid is higher than that of membrane sulfonated by sulfonic acid. Although the ion-exchange capacity of membrane quaternized by methyl iodide is higher than that of membrane quaternized by methylene diiodide,mechanical properties of the former are too poor to form membranes. The ion-exchange membrane with higher ion-exchange capa-city will result in lower concentration membrane potential,higher membrane conductivity and water content.
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发布时间：2021-03-19 - 摘要：1-Butene was polymerized with highly active supported titanium catalysts which was developed in this laboratory. The influences of various conditions such as catalyst composition, temperature, triethylaluminum concentration, catalyst concentration, adding ester and H2 on the catalytic activity, decay of polymerization rate,inh value and isotactivity of resulting products were studied in detail. The structure and properties of poly (1-butene) were also studied by WAXD, DSC and 13C-NMR.It was found that TiCl4, Ti (OBu)4/MgCl2/ethylbenzoate (EB)/(C6H5)2SiCl2/AlEt3 catalyst had high catalytic activity,i.e. 3.2×104g.PB/g.Ti.h Isotacticity of ploducts was increased by adding P-CH3H6H4COOEt. i.e. I. I. %= 93.3.Molecular weight ofproducts was controlled by H2.The decay of polyme-rization rate with time fulfills the equation:Rt-Rs=(Ro-Rs)e-βt.
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发布时间：2021-03-19 - 摘要：The transformation of the spherulites of nylon 1010 has been studied by means of PLM. In cooling process, the nonringed spherulites formed above 195℃ could be changed into the same birefringent ringed spherulites below 181℃.In heating process, positive ringed and nonringed are transformed into positive and negative nonringed forms at 182 and 194℃ respectively and 2-valve spherulites became negative nonringed at 183℃ which returned Into 2-valve at 178℃. When a few kinds of spherulites coexisted, positive, mixed ringed and nonringed could be changed into 2-,asymmetric 4- and 6-valve spherulited in 109-158℃,and all changed into ringed form at 203℃ then melted at 216℃.
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发布时间：2021-03-19 - 摘要：Due to the distinctive structure characters,the rare earth metal ionomers have mech greater Water absorption than some others. The effects of carboxylic content, degree of neutralization, metal ionic species, contra-ionic species, temperature and time on the water absorption of ionomers were studied in detail.
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发布时间：2021-03-19 - 摘要：Group transfer polymerization(GTP) of methyl methacrylate with 1-trimethylsiloxy cyclo-hexene(TSCH) as initiator, tetrabutylammonium bibenzoate(TBABB) and mercuric iodide (HgI2) as catalyst was reported HgI2 is a catalyst for the GTP of MMA which gives high conversions and requires far less amount. The activity of TBABB catalyst is depended on the structure of the anion and cation. The effects of catalyst concentration on polymerization rate, Mn and monomer conversion were studied.
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发布时间：2021-03-19
Research Article
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EFFECT OF THE DONOR IN THE HIGHLY ACTIVE CATALYST ON THE KINETIC BEHAVIOR OF ETHYLENE POLYMERIZATION
摘要：Two catalysts were prepared using reaction method with or without dibuthylphalate(DBP). The surface area, X-ray diffractions and kinetic behavior for ethylene polymerization of these catalysts have been compared. It was found that when the catalyst without DBP(WY-1 system), the kinetic curves for ethylene polymerization show decaying type; however, when the catalyst with DBP(WY-2 system), the kinetic curves are accelerating type. The specific number of active centers [C*] are almost same in the two systems. The value of kp of WY-2 system was much greater than that of WY-1 system,but the apparent activation energy of WY-2 system was much lower than that of WY-1 system.It leads to that the catalytic activity of the catalyst with DBP increased greatly in comparision with that of the catalyst without DBP.- 27
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发布时间：2021-03-19 - 摘要：PCILO conformational calculations have been carried out on several model compounds of mesogenic cores of liquid crystalline aromatic polyesters,-CO-O--O-CO-,-CO -O-CO-O- and -O-CO-CO-O-.The calculated structures can be compared to the X-ray crystallographic data. In addition, bond orders of the model compounds were also obtained by using CNDO. It has been found that the three phenylene rings statistically take orientations perpendicular to each other, and that when the carbonyl group turns into plane of the phenylene ring which is not the immediate neighbor but the one through the ether-oxygen,the best conjugation reached is not accompanied by the lowest conformational ener-gy.
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发布时间：2021-03-19 - 摘要：4-Acetamino-4'-methacryloylaminodiphenylmethane (AMDPM) monomer was synthesized from 4,4'-diaminodiphenylmethane via acetylation reaction and then reacted with methacryloyl chloride. AMDPM monomer was characterized by elemental analysis,1H-NMR and IR spectra. In the presence of 2,2'-azobisisobutyronitrile (AIBN) AMDPM polymerized and formed a brittle homopolymer. The copolymers of methyl acrylate(MA) with AMDPM in various molar ratio were synthesized via free radical polymerization in N,N-dimethylformamide solution.The monomer reactivity ratios were determined by Fineman-Ross method.
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发布时间：2021-03-19
Research Bulletin
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