最新刊期
卷 ， 期 1 ， 1983
- 摘要：The optimal conditions of rosin modification of unsaturated polyesters were found and the reaction mechanism which consists of both Diels-Alder addition reaction and esterification were investigated by means of IR, UV, NMR, and MS and by comparison with some related model compounds. It has been found that this chemical modification is mainly due to the reaction of the terminal hydroxyl groups of the polyesters-and the branching effect of Diels-Alder products, and hence, the water resistance, chemical resistance,chemical resistance and the compatibility with styrene of the polyesters are improved.
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发布时间：2021-03-19 - 摘要：The parameters, K and a of [η] = KMa/w, for 1,2-polybutadienes at 30℃+ in toluene, has been determined. It has been found that the values of a of samples with various 1, 2-unit contents are basically the same, but the values of K decrease with increase in 1, 2-unit content.The relation between T0 and σ of the samples has been found to be Tg=A(σ-b), in which A and b are 174 and 0.68, respectivly, indicating the internal rotation of the molecular chain is hindered by 1, 2-unit.It has shown that less 1, 2-unit content corresponds to lower poltential barrier of internal rotation and hence to lower energy of rotational isomerization.
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发布时间：2021-03-19 - 摘要：The crystallization kinetics of poly (phenylene sulfide) (PPS) and its carbon fibre composites were investigated by dilatometry. An appreciable deviation from the Avrami equation was found for PPS-carbon fiber composites. PPS exhibits a moderate crystallization rate, and possesses a low σσ value, packing density coefficient kc, and a low pre-exponential term G0 of the equation of crystallization kinetics, in compare with polymers such as PE, PMO etc. Go has been found to be the chief factor for the crystallization rate of polymers. Those polymers which possess a lower ρa/ρc value will probablly show a higher crystallization rate.
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发布时间：2021-03-19 - 摘要：Plasma polymerization of tetrafluoroethylene and chlorotrifluoroethylene was conducted in a capactive coupling external electrode apparatus. Eesults from IR, X-ray diffraction and elementary analysis show the polymer formed in the glowing region of plasma has a lower concentration of -CF2-groups and therefore it becomes a cross-linked product. IR spectroscopy was used to study some of the optical properties of plasma polymerized films. The films have a better transmittance over a wide spectral range and have good thermostability.
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发布时间：2021-03-19 - 摘要：The aim of this paper is to get the curve of log[n]--logM of the sample tested，in the absence of a linear polymer of sample of same chemical composition based on universal calibration．The linear seetion of the curve is extended in the direction of increasing molecular weight．The [n]L values of unbranched and branched toolecule of same MW are determined by the points on lines，and／or for linear GPC’s columns，the linear section of log [n]-V might be extended in the direction of decreasing elu-tion volume．The poInts on extended lines might determ,ine [n]L value of the linear and branched sample of same elution volume．Thus， ([n]b/[n]L)M=G or ([n]b／[n]L)Ve一G，is obtained．The experiments proved that the branching has an effect on M[n]，i．e．Mb[n]b= ML[n]L．Correction must be made．After correction such as Mb[n]b=ML[n]L2一G)，the [n]b and Mw values calculated from th e data obtained via GPC coupled with an automatic viseometer agreed well with corresponding values measured by classical viscometry and light scattering method．
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发布时间：2021-03-19 - 摘要：The ultrasonic degradation of poly(ethylene oxide) and poly(vinyl acetate) in benzene solution, and grafting reaction of poly (vinyl acetate) with poly(ethylene oxide) were studied. It has been found that the chain-scission reactions follow the course suggested by Ovenall, D. W. The structure of the copolymer was identified by IB, NMB and DTA, to be a graft copolymer mainly. The copolymer, formed by irradiating 1% PEO-PVAc solution (PEO/PVAc = 1/1 by weight) for a period of 10 min. at 18.2 kHz with 2.0 A input current on reversed main circuit,amounts to 10.54%.
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发布时间：2021-03-19 - 摘要：Polyethers eould form hydroperoxide under air-oxidation or photooxidation in the presence of H2O2．The scission of ether linkages induced by moderate oxidation was prevented by controlling the reaction time and hydroperoxide concentration．The oxi-dation rate was affected by the end group S of polyethers．The decreasing order of oxidation rate for various poly (oxytetramethylene) derivatives having different end groups are as follows：poly (oxytetramethylene) glycol (PTMG)> poly (oxtetra-me thylene)acetate(PTMGAC)>poly(oxytetramethylene)phenylamino formate (PTMGPIC)．The urethane end groups in PTMGPIC increase the resistance toward oxidation．Polyether hydroperoxide reacts with ferrous ion or N，N-dimethyl-p-tollli-dine (DMT) to form polymeric·oxy radical which then initiates the graft copolymeri-zation of vinyl monomers at low temperature，and was devoid of homopolymerization．The eopolymer after separation and purification was proved to be a graft one by IR analysis and elemental analysis．
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发布时间：2021-03-19 - 摘要：One linear and four branched polyvinyl acetate (PVAc) samples were polymeri-zed and fraetionated．Intrinsic viscosities [n]，weight average molecular weight Mw (by LALLS) and GPC ehromatograms were measured for the fraetions．The Mark．Houwink equation for linear PVAc in tetrahydrofuran at 25℃ was found to be [n]=1.62×10-2 M0.698w K and a values for PvAe samples with different degree of branching were also obtained when linear relationships were assumed．From the values of K and a of the branched samples it is possible to talculate the eritical molecular weights Mc's g which eharaeterize the point of separation in molecular weight between the linear and branched moleeules．Different parameters which characterize the degree of branching were ealculated and compared．
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发布时间：2021-03-19 - 摘要：A kinetic analysis of star coupling reaction of living polymers has been carried out. The molecular weight distribution function and some molecular parameters of the pre-polymers are concerened in those of prepolymers. The conclusions obtained include that the more arms the star polymer has, the more homogenious is it; when the degree of branching is large enough, the star polymer follows the normal distribution inspite of the dispersity of prepolymer.
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发布时间：2021-03-19 - 摘要：The transitions of copolymer of tetrafluoroethylene-hexafluoropropylene (FEP) were studied by using the dynamic mechanical and dielectric relaxatiOn methods．Three mechanical transition peaks i.e．a.β and γ，were observed over a temperature range from一90℃ to 160℃ for FEP eop olymer．Efleets of HFP content on the transitions were discussed． Similar to mechanical relaxation．there are three transi．tion peaks of a-γ and δ existing between —186 and 150℃ by dielectric method．Ex-perimental data showed that the peaks measured by dynamic mechanical method are consistent with the peaks measured by dielectric method．The meehanism of dielee-tric δ transition is explained in detail．
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发布时间：2021-03-19
Research Article
- 摘要：A series of styrene (st) and 2, 2, 6, 6-tetramethyl-4-piperidinyl methacrylate (MTMP) copolymers were prepared by free radical copolymerization and their IR spectra were measured.It was discovered that the 1152.5 cm-1 band of MTMP was shifted to lower wave numbers with a decrease in the content of MTMP in the copolymer.This displacement of wave number of this band is approximately proportional to Fams which is called triad sequence distribution.The diad sequence distribution Pmm which was calculated through measuring the position of the ve=O of MTMP was discussed.
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发布时间：2021-03-19 - 摘要：The photo-stabilizing effect of 2，2，6，6-tetramethyl-4-hydroxy-piperidine (TMP) and 2，2，6，6-tetramethyl．4．hydroxy-piperidine-N-oxyl (TMPO) alone and with 2-hydro-xy-4-oetyloxy．benzophenone(uv-531) on polypropylene (PP) films has been investi-gated．Expermental results show that both TMP and TMPO．synergise with uv-531．It is shown also that the decrease in concentration of uv-531 obeys first-order kinetics in films containing uv-531 alone and with TMP and TMPO and the rate constants in cases of films containing uv-531 with TMP and TMPO·are less than that of films containing UV-531 alone．Fronl these facts it has been suggested that the reason of synergism of studied stabilizers consists m ainly in that N-oxyls can scavenge active radicals pro．duced in photooxidation of PP films and inhibite effectively the formation of carbonyl compounds and hydroperoxides and thus protect uv-531 from．photo-des-truction during the photo．oxidation of PP．
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发布时间：2021-03-19 - 摘要：The condensation aligomers of 5-fluorouracil were ppepared by reacting 2，4 bis-(trimethylsilyloxy) 5-fluoropyrimidine with various dicarboxylic chlorides，e．g．The structural eharacteristics of the ohgomers obtained were investigated by IR．1HNMR．The oligomers were then hydroly zed in acid．alkaline and neutral medium at room temperature respectively and the amount of 5．fluorouracil released was guan-titated by measuring its absorbanee at 266.5nm. However．in the case of oligomers containing phenylene moiety，5-fluorouraeil was not detected，when the hydrolysis was conducted in acid or neutral medium．while in the case of oligomers containing methy-lene moiety，hydrolysis proceeded readily in acid，alkaline and neutral medium．
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发布时间：2021-03-19 - 摘要：A silica-supported poly-y-mercaptopropylsilioxane-platinum complex has been prepared and found to catalyze the addition o f triethoxysilane to 1-hexene at 80℃ or room temperature.This complex is very stable throughout the reaction and can be reused many times without appreciable loss in the catalytic ac tivity.The addition of triethoxysilane to acetylene can also be catalyzed by this complex at room temperature to give vinyltriethoxysilane and 1, 2-bis-(triethoxysilyl)-ethane.
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发布时间：2021-03-19
Research Bulletin
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