最新刊期
卷 ， 期 6 ， 1987
- 摘要：The effects of MW, MWD, winding speed and other spinning conditions on the texture formation of PP fibers were studied. The experimental results show that the resins of lower MW and narrower MWD can be spun nicely up to a speed of 5300 m/min. A gradual transition from smectic to a-crystalline structure of the as-spun fibers with increasing spinning speed can be observed. The magnitude of the birefringence of the as-spun fibers in a-crystal-line modification is roughly in the order of increasing value of the index for c-axis orienta-tion. Thus,selection of suitable resin and processing parameters to controll the texture of fibers offer new route for high speed spinning of PP fibers to improve the mechanical pro-perties of end-use fiber products.
- 5
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Seven new polyphosphates containing both nucleic acid base and nitrogen mustard were prepared by reacting the monomers, i.e. l,3-dihydroxyalkyl-5-fluorouracil (IIa,b,g), 1,3-dihydro-xyalkyluracil (IIe,d) and 1,3-dihydroxyalkylthymine (IIe,f) with N,N-bis (2-chloroethyl) phospho-ramidic dichlorid (I). The monomers and polymers were structurally characterized by 'H-NMR, IR spectra and elemental analysis. All of the polymers obtained are soluble in water. The antitumor activity of some of these polymers were tested against Ehrlish ascites in mice.The results showed that the polyphosphates containing both 5-fluorouracil and nitrogen mustard exhibit the lower toxicity and higher antitumor activity. The inhibition ratio of the polymer (IIIa)is 66%.
- 35
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：The radical copolymn. of poly(St-b-EO)-MA macromer (I) with St, MMA, MA(M2) has been studied in various solvents: benzene, THF, DMF. The reactivity ratios (r2) were calculated by the Kennedy's equation. It is observed that in all these systems there is a marked solvent effect on In(1/r2), which can be correlated to the different dielectric constants (ε) and to the difference between solubility paremeter of growing active chain and that of solvents.
- 42
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The amide-salt solvent system containing N-methyl pyrrolidone and LiCl or CaCl2 is generally used for the synthesis of PPTA. In this paper the associationdisassociation equilibrium and solvation existing in the solvent system were studied. The experimental results showed that there were multiple association-disassociation equilibrium in the solvent system and strong solvation of the cations. The higher the free-ion concentration and the solvation effect, the higher the molecular weight of the polymer was obtained.
- 23
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The morphology of β-modification of isotactic polypropylene (β-IPP) has been studied by polarizing microscope (PLM) and scanning electron microscope (SEM). Under PLM β-IPP appears as colored spherulites with twig-like structure. SEM photographs of β-IPP give petal-like and twist curve lamellar structure. A model for β-IPP spherulites growth has been advanced.
- 13
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：The variation of the MW and MWD of cis-polybutadiene in the course of polymerizauon catalyzed by lanthanide complex composed of triisobutyl aluminium or diisobutyl aluminium hydride was investigated by osmometry, viscometry and SEC. By analyzing the experimental data, the reasons of the appearance of bimodal MWD of lanthanide cis-polybutadiene and the possible mechanisiums of polymerization were discussed.
- 30
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The morphology of polyacrylamide has been studied by electron microscopy. Single spherical molecules of polyacrylamide can be obtained by spray technique from very dilute solution in water-n-propanal mixture. The molecular weight and molecular weight distribution were calculated using electron microscopical method. The influence of percentage of solvent-precipitant mixture, concentration of solution and method of spray on the morphology and the results of calculation have been discussed.
- 6
- |
- 10
- |
- 0
发布时间：2021-03-19
Research Article
- 摘要：An immobilized cellulase was prepared by the immobilization of cellulase with a complex of polymethacrylic acid and polyvinylpyridine for the use of transformation of cellulose to glucose. It has been found that the yield of glucose is affected by molecular weight of polymer support, pH value of solution, reaction temperature and so on. The immobilized cellulase was more stable than the soluble cellulase. It could be reused ten times and stored for 25 days without appreciable loss in catalytic activity.
- 27
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：In this paper, 25 MHz proton-decoupled 13C NMR spectra of isotactic and atactic smaptes polymerized with high effective supported catalyst using diester, C6H4[COOCH2CH(CH32)]2, as inester and (CH2O)3Si(C6H5)2 as outester have been determined. The values of triad and pentad tacticity have been calculated from the expanded spectra of methyl carbon region. The kinetic models of stereospecific polymerization mechanism have been discussed. Machanism of higher tacticity for samples using diester high effective supported catalyst system than using monoester supported catalyst system bave been quantitative explained from theoretical model of three parameters.
- 2
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The synthesis of PS macromer with the method of cationic polymerization was studied. Styrene monomers was initiated by BrCH2CH -CH2Cl/AlEt3 and thePs macromer with narrow MWD(1.4) was obtained. Under certain extent, the mole. cular weight of the Ps macromer can be controlled. The Ps macromer with structureCH3=CH - CH2-Ps was characterized by UV spectra and GPC. They werecopolymerized with ethylene and propylene and vinyl acetate. The products of copo-lymerization were graft copolymers EP-g-Ps and PVac-g-Ps.
- 4
- |
- 10
- |
- 0
发布时间：2021-03-19 - 摘要：The molecular weights of tetrahydrofuran (THF) polymerization products by BF3-epich-lorohydiin (ECH) catalyst system at 0-2℃ monthly increase as the reaction proceeds in dry conditions. A small amount of water introduced into the reaction system will sharply increase the molecular weight at high conversions. The molecular weight of the product could be precisely controlled at the molar ratio of water and BF3 being around 1.23 with high yield above 60%. The hydroxyl end-group functionality of the product is close to 2 and the content of the ECH derived units in each chain containing about 26.5 THF derived units is around 1.3.
- 31
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：A Covalently bounded immunoassay beads has been prepared by entanglment styrene-acrylic acid copolymer to the surface layer of polystyrene beads, then the protein (Hepatitis B antibody) bounded with the functional group (carboxylic acid) in the modificated layer .The methods of preparation, the influence of the conditions of preparation and immersion of the copolymer on the properties of modificated beads and the results of testing for the Virus of Hepatitis B are discribed.
- 3
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Polyvinyltetraphenylphenylsiloxanes were synthesized by Diels-Alder reaction of polyviny-lsiloxane with tetraphenylcyclopentadieneone, using a novel method. Their structures were determined by spectral analyses. Their thermal stabilities were also investigated in this paper.
- 35
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The beads of styrene, N-vinylpyrrolidone (10%) and divinylbenzene (3%) copolymer were synthesized and combined with titanium tetrachloriele in chloroform to form a stable complex containing 14.12% of chlorine which correspond to 9.94 ×10-4 mol TiCl4/l g complex beads. The complex can be used to catalyze a lot of organic reactions in high yield, such as esterifica-tions, acetalizations, ketal formations, etherifications and the Friedel-Crafts alkylation. The complex is more stable and more reactive than polystyrene-titainium tetrachloride complex,and can be reused at least 7 times.
- 36
- |
- 7
- |
- 0
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