最新刊期
卷 ， 期 3 ， 1993
- 摘要：DSC was used to study the changes of enthalpy relaxation behavior of blends of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO)and benzoylated PPO(31. 0 mol% and 43. 3 mol% of benzoyl group respectively) (BA31.0-PPO, BA43.4-PPO). It was found that for the miscible blend of BA31.0-PPO/PPO, there was only one endothermal peak during the isothermal annealing. This behavior was very similar to that of PPO/PS blend. But for the BA43.4-PPO/ PPO blend whose miscibility was unknown, there were two endothermal peaks during the an-nealing,and the Tg values of the two peaks were very close to those of pure components of BA43.4-PPO or PPO. The results of SEM micrographs indicated that BA43.4-PPO/PPO was two phase system. So the enthalpy relaxation can be used to study the compatible properties of blend of PPO and its derivatives which have similar Tg.
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发布时间：2021-03-19 - 摘要：The crystallization behaviour of polydisperse and monodisperse poly (ethylene oxide-styrene-ethylene oxide)triblock copolymers has been studied, including these samples, of which the microphase separation took place first at high casting temperature and then crystallized at room temperature. The results show that the crystallization behavior of the copolymer could be very different when its microphase seperation is different due to the polydispersity of its molecular weight, the different casting solvents, and the castng temperature which affect the crystalline ability of PEO blockof it.
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发布时间：2021-03-19 - 摘要：A series ionomers of sulfonated ethylene-propylene copolymers containing -SO3Na group from 0 to 12. 0 mol% have been prepared by hydrolysis of chlorosulfonated copolymers. Three methods were used for analysis of sulfur and chlorine contents in ionomers. Decrease in crystallinity for ionomers with increase in -SO3Na group concentration was showed by DSC and WAXD curves. The ionic peak in the LAXD curves and the marked increase of T, with ion concentration were observed only for ionomers sulfonated above 5-7 mol%. These facts were considered to be evidences for the existence of ionic clusters in sulfonated above the critical concentration.
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发布时间：2021-03-19 - 摘要：The mixture of Hexamethoxymethylmelamine (HMMM)-triethylene glycol(T3EG) and triethylene glycol dimethacrylate (T3EGMA) can be cured by hybrid polymerization consisted of condensation polymerisation and radical polymerisation at higher temperature in presence of latent acid catalyst such as t-2-hydroxy-cyclohexyl tosylate(TCHTS) without radical initia-tor．This mixture system provides a synergetic effect on curing reaction，and that has been at-tributed to the presence of adventitious peroxides and the conversion of peroxides to initiating tadicals．It has been considered that The HMMM is not only a crosslinking agent but also an accelerater of the oxidation of active methylene groups，and the acid generated from TCHTS plays the role of the catalysts for the conversion of hydroperoxides into free radicals as well as．for the transetherification．This consideration is supported by the results of the oxygen ab-sorption examination，active oxygen content determination and gel time studies．
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发布时间：2021-03-19 - 摘要：The birefringence property of Hard Elastic polypropylene(HEPP) fiber is different from that of usual PP fibet，because it will produce a lot of microvoids on the stretching，which is observed by SEM．Furthermore，the elasticity of HEPP fiber will be reduced in an infiltrating medium(e．g．silicon oil)，and be constant in a unfiltrating medium(e．g．water)．When the medium was infiltrated into the microvoids，the surface energy will be decreased，and the e-lasticity will be reduced also．Meanwhile it is the microvoids structure that results also in change of its birefringence properties，becaust of Form Birefringence (△form)．The birefrin-gence of HEPP fiber is measured on the stretching in the different medium by polarized mi-croscopy using compensator．It was found that there is a maximum extreme value of HEPP birefringence to different draw ratio with increasing the refringence of various infiltrating me-dia．In this case，the refringence of HEPP fiber iS equal to that of the medium (n=1.54)，and Form Birefringence is equal to gero．
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发布时间：2021-03-19 - 摘要：Silver and copper foils for surface enhanced Raman study were prepared by chemical etching method with HNO3. These foils exhibit better enhancement factor and higher thermal stability than the vacuum deposited silver island film. The surface geometry of poly (4-vinylpyridine) and polybenzimidazole has been determined by observing relative intensity change of the out-of-plane and in-plane ring vibration bands in their SERS spectra. The two polymers show two orientations in which the rings are "lying down" or"standing up"from the surface resulted from different sample methods.
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发布时间：2021-03-19 - 摘要：Emulisifier-free copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) in the presence of surface active comonomer, Sodium undecylenic acid (at concentration below its CMC) are carried out. The influence of polymerization conditions such as SUA content, KPS content and ionic-strength on kinetics are examined. The particle diameter, number , morphology, growing process,as well as polymerization mechanism are studied by means of Particle Size Analysizer,TEM, GPC,IR Spectra and Ionic-Exchange-Conductimetric titra-tion. The results indicated that particles are generated through a combination of homogeneous nucleation and micellar nucleation mechanism.
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发布时间：2021-03-19 - 摘要：The kinetics of crystallization and liquid crystallization from isotropic melt were investigated. The analysis of experimental data in different temperatures leads to the suggestion of nucleation and growth mechanism of studied polyesters. The morphology of spherulite formed on crystallization of liquid crystlline polymers was also discussed.
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发布时间：2021-03-19 - 摘要：Molecular weight and molecular weight distribution of PBT were determined by GPC at room temperature. A room temperature solvent of o-chlorophenol / chloroform mixture (1 : 3 by volume ) was found by means of theoretical calculation of the solubility parameters. GPC experiments showed that this mixed solvent can be used as an eluant of GPC at room temperature.PBT fractions were obtained by fractionation and were characterized and used as standards to calibrate the GPC column. [η]-M equations of PBT and PS in this mixed solvent at 25℃ were obtained. Universal calibration was found to be applicable for PBT in this system.
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发布时间：2021-03-19 - 摘要：High reactive bisvinyl macromonomer (BPS-MA) introduced into the system of styrene, methacrylic acid and metal salts of monomers, the reactivity of the system can be regulated by adjusting the content of BPS-MA. The study of relationship between monomer ratio and resin transparency shows that without BPS-MA in the system, at the ratio of methylacrylic acid vs Pb monomer MA/Pb(MA)2>6. 0, transparent resin can be obtained; BPS-MA 20%, MA/ Pb(MA)2 2. 2, transparent resin with high refractive index (nD>-1. 60),can be obtained. The study of optical properties indicates that with the ratio of Pb(MA)2,BPS-MA increases,nD of the resin will increase but Abbe number uD decreases a little. At certain ratio of the monomers, multicomponent metalcon-taining transparent polymer materials can be reached,which has excellent properties.
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发布时间：2021-03-19 - 摘要：The configurations and the collapsed polymer state of a semi-stiff chain under various temperatures, especially below the theta point ,are presented in this paper. The Monte Carlo method is used to simulation the behavior of a semi-stiff polymer chain in simple cubic lattice. In our model the inter-segmental interactions included the hard core volume effect, longer ranged attractive part and the local stiffness potential. The stiffness of a chain is determined by the ratio of stiffness potential and attractive effect. Our results have been obtained show-ing a shrinkage of the coil dimension of a polymer chain with decrease temperature. But there has some differences between a flexible chain and a semi-stiff polymer chain. At first the soil demintion of a semi-stiff chain is expanded due stiffness potential,then it shrinkage with de-crease temperature. From the behaviou of the specific heat we concluded that the collapsed transitions of a polymer chain is a second-order phase transitions.
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发布时间：2021-03-19 - 摘要：The possible crystal structures of I-PP have been investigated by means of the theory of crystal symmetry.1.The dichromatic space groups of C2/c have been derived. Arrangements of the helical chains in these dichromatic space groups have been studied. Five possible space groups of I-PP (α-form) were given.2.A model of the crystalline structure of the a-form I-PP in which Cc and p2/c space groups are consolute has been proposed from the crystal domain theory.3.The arrangements of PP helical chains in a hexagonal crystals β-form have been inves-tigate. The most possible unit cell with nine chains passing through the cell has been suggest-ed. that is a R-type cell in which PP helical chains were placed in a semi-random fashion.
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发布时间：2021-03-19
Research Article
- 摘要：To investigate emulsifier-free copolymerization in the presence of a solid phase, copoly-merization experiments were carried out for the Styrene-Butyl Acrylate-K2S2O8-Water system by using barium sulfate powder, which is assumed to be chemically inert. Reactions were varied with respect to ranging barium sulfate powder quantity, initiator concentration and temperature. These factors were inquired into effect on reaction rate and conversion , polymer particle number and diameter,and latex stabililty.
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发布时间：2021-03-19 - 摘要：It is demonstrated that surface tension diffefence (△γ) can neither act as interfacial ten-sion (γ12) nor as a substituent of γ12 in polymer studies．At present，△γ is still being wrongly used as substituent of γ12 in polymer investigation，because γ12 in polymer system is very diffi—cult to measure．With a purpose to solve the problem，an estimating method of γ12 from the value of breaking energy based on the domain prediction theory of polymer blends developed by the authors is proposed as：γ12=E／3B where B is the experimental constant in domain pre-diction theory; E is macroscopic bulk breaking energy of particle in polymer blends．Using this method，γ12 of any polymer system can be obtained so long as E and B are known．In the case of EPDM，the value of E at 195℃ was found to be 3.3×102J／M3．Besides，two equations based on the modification of Wu’s equation and Girifalco’s & Wu’s equation are proposed to fit some special cases as：When the structure and composition of two polymer materials are almost same．Where γ1 is surface tension of polymer l at temperature l (T1) γ1’is surface tension of polymer l at temperature 2 (T2) γ2 is surface tension of polymer 2 at T1 γ2’is surhce tension of polymer 2 at T2 (T1-T2≈10℃)
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发布时间：2021-03-19 - 摘要：This paper is based on the mechanism of UV photodecomposition of polysilane，utilizing the sflane free radical generated from the photodecomposition to initiate the polymerization of monomer styrene．Studies of the influences of initiating time，concentration of polysilane，and UV characteristic absorption wavelength (λmax) of polysilane on the percentage of olymerized conversion，show that polysilane can be characterized as photoinitiator．The percentage of conversion increases with the square root of the concentration of polysilane．The closer the λmax is to the wavelength of source light，the more effective the polymerization is．
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发布时间：2021-03-19 - 摘要：The structure of the nylon 6 fiber irradiated by γ-ray was analyzed. The results show that during the irradiation process the molecular chain is degradated,the crystallinity increaspes,while the crystalline orientation dose not change.
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发布时间：2021-03-19 - 摘要：A new synthetic method for biomedical materials poly (ε-caprolactone)(PCL) initiated by the catalyst Ti(OBu)4 has been investigated．The test has shown that the average degree of polymerization DP is linear with monomer／initiator M/I．The relationship between the．poly-met molecular weight Mw and reaction temperature，reaction time also is obtained PCL is characterised by IR，1H-NMR, 13C-NMR and DSC．The analysis results indicated that PCL synthesized by this method is no difference as compared to that obtained by other methods on polymer structure and performance．In vitro the Nifidipine and Lauryl Alcohol microspheres prepared by the solvent evapora-tion method using this materials as substrate were found to give excellent sustained release performance．
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发布时间：2021-03-19 - 摘要：The initiation，propagation and breakdown of crazes in uhrathin film of a-phase isotatic polypropylene with different molecular weight during slow tensile process in TEM have been observed．The local orientation of lamellea in spherulites changed the straightforward propa-gation direction of crazes．Most of crazes irdtiated in the spherulites．The microfibril break-down became easier as the molecular weight decreased，and most of the fibril breakdown took place in the middle．It was different from that in PS where fibril breakdown occurred in the strain softened zone at the craze-bulk interface．
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发布时间：2021-03-19 - 摘要：Effect of polar acrylamide (AM) group on the conductivity of Li+-conducting polymers is studied，in which the conductivity data are analyzed by Vogel-Tammann-Fulcher(VTF)equa-tion and interpreted by the configurational entropy model．The linear VTF pohs revealthat there is a close correlation between ionic conductivity and segmental motion of the polymers．Polar AM groups may enhance the dissociation degree of the salt species and lower the activa-tion energy of exchange process of the Li+-O bonds during ionic transport，but also increase the rigidity of polymer segments．As a result，ionic conductivity of the copolymers is promot-ed as long as AM content is below ca．15 wt％．
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发布时间：2021-03-19 - 摘要：N-(p-Dimethylaminophenyl)maleimide (DMAPMI) was synthesized and copolymerized with vinyl acetate. The photochemical behavior of DMAPMI and its polymer was studied. It was found that the intensity of monomer was lower than that of its copolymer due to the structural self-quenching effect as we have reported previously. The relationship between Stern-Volmer constant and 'e' value of quenchers was discussed. DMAPMI could act as both of a photosensitizer for vinyl polymerization upon UV irradiation and a component of redox initiation system by combining with BPO to initiate the vinyl thermo-polymerization.
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发布时间：2021-03-19 - 摘要：The complexes of linear 4-vinylpyridine-methyl vinyl ketone copolymers as ligands with tetracarbonyldichlorodirhodium have been found to be able to catalyze the methanol carbony-lation to produce acetic acid in a mild reaction condition. Experimental results show that these macromolecular complexes contain cis-dicarbonyl rhodium structure. There are two coordination bonds, N→Rh and O→Rh, which form the following two coordination units in the copolymer complexes:Experiments reveal that catalytic reactivity of the complexes is increasing with the aug-mentation of O→Rh bonds, while thermal stability of the complexes is elevating with the growth of N→Rh bonds content.
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发布时间：2021-03-19 - 摘要：The effects of benzaldehyde(BA)，p-nitrobenzaldehyde(PNBA)，m-nitrobenzaldehyde (MNBA)，m-bromobenzaldehyde(MBBA)，and p-ehlorobenzaldehyde(PCBA) on the poly-merization of acrylamide (AAM) in the presence of eerie ion (Ce4+) have been studied：Vinyl monomers such as AAM，acrylonitrile (AN) could polymerize using eerie ion (eerie ammoni-um nitrate) as an initiator．In the presence of eerie ion the rate of polymerization Rp of AAM could be enhanced by adding an aliphatic aldehyde to the polymerization system．Adding ben-zaldehyde，however，could not increase the Rp of AAM initiated by ceric ion．The Rp of AAM initiated by ceric ion/BA system is always lower than that of ceric ion alone．The values of overall activation energy of polymerization Ea were determined and the Ea values for ceric ion/MBBA and ceric ion/BA were evaluated to be 41.6 KJ/mol and 36.8KJ/mol respectively．The reaction of BA and ceric ion was investigated by UV spectra and the free radicalinterme-diate was detected by ESR spectrum．The end group of polymer formed was detected by IR spectrum analysis method and it revealed the presence of aliphatic aldehyde moiety in the polymer obtained with ceric ion/aldehyde system．
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发布时间：2021-03-19
Research Bulletin
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