最新刊期
卷 ， 期 5 ， 1988
- 摘要：Lifetime spectra of positron annihilation in amorphous and semicrystalline polyethylene terephthalate (PET) have been measured in the temperature range from 21 to 150℃. The lifetime data were analysed in terms of a three component fit. A sudden change of slope in the longest lifetime τ3 against temperature was found at 70℃ for amorphous and semi-crystalline PET respectively. The transition temperature obtained by this technique, so-called Ts, is insensitive to crystallinity of the sample. In general, the relative intensity of the longest lifetime component I3 increses with increasing temperature. However,due to the crystalliza-tion of amorphous sample the gradual decrease of I3 with increasing temperature between 100 and 110℃ was observed. Thus,the value of I3 is sensitive to variation of crystallinity of PET.
- 2
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：A simple empirical correction method for the intrinsic viscosity in the experiment of GPC combined with viscometer has been presented in this paper. The values of [η] remain unchanged. It is only necessary to correct the values of corresponding elution volume Vi. For linear GPC columns, an empirical correction equation was proposed as follows:where tgθ is the slope of uncorrected straight line in a plot of log [η] vs V, Vi and Vi,corr are the uncorrected and corrected elution volume for count i respectively;Si+1 Si-1 and Si represent corresonding area in chromatogram for count i+1.i-1.and i.This correction method is tested and verified by the broad sample and standard sample of polystyrene as well as the unfractionated and the fractionated samples of poly (vinylchloride) and chlorinated polyethylene. The results are satisfactory.
- 3
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：The relation between thermal degradation and carboxyl content of polyethylene tereph-thalate is investigated in the polycondensation process. It is found that in the presence of butyl titanate or stannous oxalate as a polycondensation catalyst the carboxyl content is not always on the increase in all high vacuum stage. Three methods (TGA, [η] and COOH) for evaluating thermooxidative degradation rate constants are employed and the results are discussed. The effects of single or composite stabilizers and polycondensation catalysts on the thermooxidative degradation have also been studied.
- 4
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：A series of silica-supported polysiloxane palladium complexes with N-donor ligands were prepared and used to catalyze the hydrogenation of imines. These Polymer palladium complexes showed different catalytic activity for the reaction under atmospheric pressure at room temperature. The hydrogenation of N-benzylideneaniline catalyzed by poly-(N, N-dia-cetyl)-γ-aminopropylsiloxane palladium complex was investigated in detail. It was found that the catalyst is stable and yields only one product in the reaction. The effects of the at-omic ratio of N/Pd in the complex,temperature and various substrates on the reaction are also reporte.
- 3
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The present paper establishes two equations on gelation reaction of type ∑Aa1-B2, containing two unknown numbers of functional group and weight average functionality. A quadratic equation is obtained by solving the simultaneous equation. Coefficient of the equation, functional group number and weight average functionality indirectly measured. When the method is applied to hydroxyl number determination of HTPB initiated by H2O3, the hydroxyl number is two times as large as one obtained by existing classical acetylizing method.
- 29
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：The effect of polydispersity of molecular weight distribution Mw/Mn on radiation-induced crosslinking of polyethylene has been studied. The deviation from the linearity of Charlesby-Pinner's relationship increases with Mw/Mn. A parameter v has been defined to estimate the deviation. v and Mw/Mn can be simply related with the empirical expression v=1.25-0.18(Mw/Mn)0.08 in the range of Mw/Mn experimentally studied. The Mw/Mn could be estimated accordingly with radiation crosslinking technique by means of the expression.
- 36
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：The crystalline properties and complexing ability of the amphiphilic star-shaped poly-styrene(S)-polyoxyethykne(E) block Copolymers were studied. The results show that crystal-linity increases with increase of E content or molecular weight of the copolymers. The sphe-rulites observed by quenching their melt at 20℃ or casting from CHCl3 solution appear more regular than quenching their melt at 0℃ or casting from ethylbenzene solution. These new copolymers show some mesomorphic phenomeni in toluene solution. UV spectra indicate that they can complex with picrate of alkali metals and enhance the solubility of the salt in CHCl3 or toluene.
- 35
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：Two model functions with broad distribution (Mw/Mn= 6.3) and narrow distribution (Mw/Mn= 1.22) were used in this paper. The effect of the broad and narrow distribution on the extent of correction of instrumental spreading has been examined. The calculated results showed that the differences of molecular weight, distribution of samples affect only the shape of chromatograms but not the extent of average molecular weight correction. The opinion prevailed in literature that peak broadening correction for samples wit broad mole-cular weight distribution is negligible in comparison with that of narrow molecular weight distribution is a misunderstanding.
- 42
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：A series of new amino-isopropylmercaptan type crosslinked chelating resins were prepared by the reaction of chloromethylthiirane with polyethylene polyamines H-(NHCH2CH2)-nNH2, n = 1, 2, 3, 4.These chelating resins exhibited excellent adsorption properties for the noble metal ions. The adsorption capacities for Ag+, Au3+, Pd2+ and Hg2+ were 5.3-6.6, 2.0-5.7, 2.6-4.6 and 3.8-5.7 mmol/g-resin respectively.
- 30
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：In this paper, wereport the preparation of three UV-sensitive organosilicon monomers, (Y-methacryloxy) propylmethyldimethoxyl-silane,1,3>5,7-tera(γ-methacryloxypropyl) terame-thylcyclotera-siloxane, and 1,3-di(methacryloy netyl)-1,1,3,3-tetramethyldisiloxane. By the co-polymerization of these monomers with αH, αH, ωH-perfluoroalkoxypropylmethylecyclotera-siloxanes, we synthesized a series of new UV-sensitive αH, αH, ωH-perfluoroalkoxypropyl-lysiloxanes, and studied the influence of the chemical structure of these polyorganosiloxanes on curing speed uuder UV radiation.
- 34
- |
- 8
- |
- 0
发布时间：2021-03-19 - 摘要：WAXD，FTIR，TGA have been used to investigate the effect of heat treatment on the structural properties of chemically prepared polythiophene (PT)．The thermal stability of the high-molecular weight fractions of PT (PT2) are much greater than the low molecular weight fractions of PT (PT1) by thermogravimetric analysis．Heat treatment of PT|at 380℃，for 30 min (under N2) lend to significant incgeases in crystallinity and coberence length indicative of chain growth and extension．Heat treatment of PT1 is carried out only with low-temperature．The crystallinity is improved somewhat．Low-crystallinity and long chain facilitate the increased concentration doped and con-ductivity．Crystal structure of PT belongs tO monoclinic unit cell and individual chain stru-cture for polythiophene in which the thiophene units alternate on both sides results in a stra-ight-chian conformation．Fourier Transform Infrared (FTIR) spectra of unannealed and an-nealed PT,powder with AsF5 dopant at varying doping levels have been investigated．
- 3
- |
- 10
- |
- 0
发布时间：2021-03-19
Research Article
- 摘要：The external reflection spectra giving information on the film electrochemically polymerized on metal wires have been achieved by using FT-IR diffuse reflectance optics. This technique is valid for samples with cylinderical shape and can detect a thin layer of film (130 A in thickness) on platnum wire.
- 2
- |
- 9
- |
- 0
发布时间：2021-03-19 - 摘要：The synthesis of macromolecular-drug and its behavior during the process of hydrolysis at the temperature near that of human body were studied. β-acryloxypropionic acid-styrene copolymer was used as drug carrier and it reacted with the isoniazidum drug through ma-cromolecular reaction. The IR analysis of products demonstrated that the conversion of car-oxylic group could reach 61%. The results of neutral or acidic hydrolysis of P(St-co-APA) attaching isoniazidum showed that the hydrolysis of the macromolecular-drug could be con-trolled due to the particular structure of acryloxypropionic acid unit.
- 2
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：The N-p-nitrophenylmethacrylamide (N-pNPhMA) was synthesized by the interaction of p-nhrophenylamine with methacryloyl chloride in the presence of triethylamine. This monomer was characterized by IR. and 1H NMR method.The N-p-NPhMA-co-MMA bulk copolymers have been prepared and characterized by IR and 1H NMR.The reactivity ratios of copolymerization of the N-p-NPhMA with MMA were obtained (r1 = 5.05±0.02 for MMA, r, = 0.29±0.02 for N-p-NPhMA) by using of a 'H NMR method.The N-p-NPhMA-co-MMA bulk copolymers are golden and transparent.
- 2
- |
- 13
- |
- 0
发布时间：2021-03-19 - 摘要：The graft copolymerization of vinyl monomers onto polyvinyl alcohol (PVA) using Mn3+ ion complexed with pyrophosphate as initiator has been studied. It was found that manganic ion-PVA complex is an efficient redox initiator system for the graft copolymerization. The effect of the temperature, concentration of initiator and monomer (AN) on the reaction were investigated. Under the optimum condition the conversion of AN and the efficiency of graft will exceed 80% and 95% respectively and the graft percent of PAN in copolymer will reach 80% The initiation mechanism has been proposed tentatively.
- 2
- |
- 7
- |
- 0
发布时间：2021-03-19 - 摘要：Accelerating effects of alkylthiols on copolymerization of Charge-Transfer-Complex (C. T. C.) comonomers were discovered for the first time. Experiments indicate that St/MAn (1:1) can hardly copolymerize spontaneously at 37℃, but in the presence of trace amount of thiols (RSH) the copolymerization occurs rapidly. In the range of 1.7×10-4-3.4×10-3 mol-1 for (RSH), initial rates, Rpo, almost remain constant. If set (St + MAn)= constant, Rpo, increase monotonically with increasing [MAn] . Furthermore, when feed ratio Xam=0..08--0.083,the compositions of copolymers vary from 0.28--0.33. In other words,regardless of comonomer feed ratio,MAn contents in resultant copolymers are always far lower than that of "ideal alternative copolymer",as it was frequently reported.
- 31
- |
- 9
- |
- 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