最新刊期
卷 ， 期 2 ， 1986
- 摘要：This paper reports the effect of monomer composition and drug content in the polymer-drug composite on the drug release rate. The polymer-dug were made by radiation-induced polymerization in a supercooled state at low temperature using monomers in glassy state. The major results obtained are:1. The release rate of drug such as indomethacin, whose molecular weight is large, could be controlled efficiently when the hydrophobie monomer MMA in the polymer-drug composite was increased.2. The release rate of drug such as 5-fluorouracil, whose molecular weight is small,could be controlled efficiently when the MMA and EDGMA in the polymer-drug composite were increased. 3. The release rate of 5-fluorouracil decreased with increasing ration of 5-fluorou-racil in the polymer-drug composite.4.The amount of drug reease from polymer-drug decreased with the rising of radiation dose.
- 37
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Proton-decoupled，partially relaxed，Fourier-transform NMR of 13C (operating at 50.3 MHz) in natural abundance was used to determine spin-lattice relaxation times (T1) and nuclear Overhauser effect (NOE) of individual carbon of a serier of 1,2-polybutadienes with different 1,2-unit content in solution．The microstrueture depen-dence of molecular motion and the internal motion of vinyl group in 1,2-polybutadiens have been studied by T1 and NOE．The nT1 values for carbons in cis-1，4-units were about twice as large as those for earbons in main chain of 1,2-units with the same se-quence strtmture，the nT1 values far carbons in the saine unit,become larger when the adjacent 1，2-units are replaced by 1,4-units and the nT1 values decrease sharply with increase of 1,2-unit content in the polymer．Form above it was seen that vinyl group has a intense steric hindrance for molecular motion of 1,2-polybuCadiene．The fact that nT1 values for CH is larger thanthose for CH2 in vinyl group implies that there are complex internal motion of vinyl group．It has been shown by caleula-tion that the dominant factor causing the difference in nT1 of CH and CH2 in vinyl group is its swinv in a plane perpendicular to the chain backbome．
- 38
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：By the use of polarized light microscopy, scanning elctron microscopy and chemical or solvent etching techniques, the crystalline morphologies of polyphenylene sulfide (PPS) and its blends with polysulfone (PSF) have been studied. It was found that for the PPS resin which was cured by heating in air, the crystalline morphologies in the bulk and in the surface region may be greatly different. Etching preferentially took place in the boundary of spherulites. With the increasing of PSF portion in the blend, the texture structure of blend changed gradually,e.g. a transform from a con-tinuous phase of PPS to a continuous phase f PSF,while the spherulite morphologies of PPS became irregular.
- 3
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：AB type PSt-PEO block copolymers were successfully synthesized using a-pheny-lethyl potassium as initiator in toluene, whereas ABA type PSt-PEO block copolymer were prepared by coupling reaction of TDI with hydroxyl terminated AB type PSt-PEO block copolymers. Both AB and ABA types block copolymers of PSt-PEO were characterized by NME, IK, UV, DSC and their bulk properties investigated by X-ray dif-fraction polarization microscopy and DSC.
- 34
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The growing AB block copolymer intermediate (PCL-PLA-OAi ) was extendedwith ethylene oxide at room temperature to form a HO-terminated PEO end-capped prepolymer which reacted with Teyssie catalyst, and replaced its isopropoxy groups toform an active prepolymeraupported catalyst, PCL-PLA-OCH2CH2-OAl . Ithas been proved that this prepolymer-supported catalyst was able to initiate CL polymerization in toluene at 90℃. The ABA triblocg copolymens with different length of segments with biodegradable as well as tough menbrane-forming properties have been synthesized successfully. This new synthetic method would provide a potential pothway from polylactide to form block copolymers with lactones.
- 2
- |
- 12
- |
- 0
发布时间：2021-03-19 - 摘要：The X-ray diffraction profiles of two polyphenylene sulfide samples with different crystallinity were analized by the computational resolution method of overlapping peaks (CROP). It was found that within the fitting error which was usually regarded as a reasonable value, multiple solutions may be obtained. The occurrence of the multiple solution is associated with the structure characteristics of the material studied, such as the crystallite size and the relative position of diffraction peaks of different crystal planes,and the physical and mathematical treatment inthe CROP process.
- 7
- |
- 9
- |
- 0
发布时间：2021-03-19 -
POLYETHER ELASTOMERS CONTAINING TTF STRUCTURE IN THE MAIN CHAIN, SYNTHESIS AND ELECTRICAL PROPERTIES
摘要：Two kinds of polyether elastomers containing TTF structures in the main chain have been synthesized and their structures have been identified．The model compound TTF (COOC4H9)2 has been synthesized for comparison．It is shown that iodine and bromine are good dopants for thelse elastomers．The room temperature canduetivity of the elastomers are increased about 6 orders of magnitude after doping．but the level of doping is not very high for bromine．It has been observed that the roo mtemperatu-re conduetivities of elastomers and of the model compound TTF(COOC4H9)2 after do-ping wnh iodine are of the same orders of magnitude．It is evident that the introduc-tion of soft segments into the elastomer’s main chain which doesn’t contain drawing group，offers an effective approach to obtain highly eondnmting polymers containing TTF structures in the main chain.- 33
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The polymerizations of acetylene by coordination catalysts composed of neodymium com-pounds(Nd(P204)3, Nd(P507)3, Nd(NO3)3 . 3P350, Nd(BA)3 . 3H2O, Nd(acac)3 .3H2O), trialkyl aluminum and a third component have been investigated. It is found that neodymium phosphonata-trialkyl aluminum-2-ethyl hexyl phosphonate system shows higher catalytic activity and gives high cis% polyacetylene films at 30℃.
- 2
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：Experimental observations of aeoustie emission (AE) of polymers have been ex-tended in the following aspects：1．Kaiser effect of AE during stretching of a polymer specimen before yielding has been observed for an amor,phous polymer in its glamy state．2．During stretching of an amorphous polymer in its glassy state AE appear-ed in the vieinity of yielding．while in rubbery state AE events were much fewer and weaker and appeared only before break．3．In a temperature jump from room tem-perature to 100℃ both amorphous and semi-crystaline polymers and polymer blends showed AE while not in the sudden cooling to--60℃．4．A polypropylene sample in-jection molded under differeht conditions showed that AE during stretching could re-fleet the quality of molding．
- 2
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The inhibition method using CO to determine the active center concentration C in gas-phase polymerization of propene were studied. The method is found to be also reliable when used in gas-phase polymerization and mainly affected by the "repeating inhibition" of CO to the active centers. It is proved experimentally that polymerization rate decay coincides with the decrease of C.
- 30
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The crosslink copolymerization of styrene (S) and diethylene glycol dimethac-rylate (DEGDM) was carried out in and without the presence of diluents, and the kinetics, phase separation and gelation were investigated. The reactivity ratios (60℃) were found to be y(DEGDM)=1.85 and y(S)=0.54. The dependence of both time and conversion at the onset of gelation on concentration of DEGDM were obtained. And the effect of properties of the reaction and product on crosslinker and diluents were examined systematically. Some experimental results were explained with microgel formation theory.
- 9
- |
- 7
- |
- 0
发布时间：2021-03-19
Research Article
- 摘要：Thermodynamically active parameters of hydrolysis of p-nitrophenyl acetate (PNPA) catalyzed by salicylic acid and its condensation polymers with formaldehyde and alkyl primary amines (alkyl=methyl, n-hexyl, or n-dodecyl) were determined under different temperature and the effect of temperature on catalysis of condensation polymers was discussed.
- 31
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：In this work, a new photostabilizer-2, 2, 6, 6-tetramethyl-4-piperidinylsalicyla-te (TMPS) has been synthesized by ester-exchange reaction between 2, 2, 6, 6-tetra-methyl-4-piperidinol and methylsalicylate. Its physical characteristics including data of nitrogen content, infrared spectrum and NME spectrum were shown. The photos-tabilizing effect of TMPS and Tinuvin 770, PDS on the photodegradation of cis-1, 4-polybutadiene has been investigated for comparison. The results observed show that the most effective stabilizer of the three is TMPS. The reason of the good photostea-bilizing effect of TMPS was discussed by fluorescence spectra.
- 32
- |
- 7
- |
- 0
发布时间：2021-03-19 -
SYNTHESIS OF SEGMENTED COPOLYMERS WITH ARYLCARDOSULFONE OR ARYLAMIDE-IMIDE OLIGOMER AS HARD SEGMENTS
摘要：Two series of segmented copolymers, with arylcardosulfone and arylamide-imide oligomers as hard segments respectively, were synthesized. The structure of the oligo-mers and the segmented copolymers obtained has been characterized.- 34
- |
- 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