最新刊期
卷 ， 期 3 ， 1989
- 摘要：A audy has been made of the crystallization behavior of poly (ether-ether-ketone)，PEEK，and the matrix of its carbon fiber composite，APC-2，under isothermal crys,tallization con-didons．A differential scanning calorimeter，DSC，was used to monitor the energetics of the crystallization process from the melt and from the rnbbery amorphous state．The Avrami equati cm was used to analyze the kinetics of isothermal crystallization of PEEK and APC-2．The mean Avrami exponents，n，for PEEK are 5.0 and 3.9 for the crystallization process from the melt and from the rubbery amorphous state，respectively，while APC-2 are 3.5 and 2.3 on the same conditions．The activation energies for PEEK are 532.1 KJ／mol for crystalliza-tion from the melt and 531.7 Ka／mol for crystallization from the rubbery amorphous state，while APC-2 are 444.2 and 432.5 KJ／mol on the same COnditions．The results of our studies show that the surface of carbon fiber of APC-2 samples has strong effect of nucleating agent on the crystallization of PEEK matrix，and decreases the activation energies of crystal-lization process of PEEK matrix．so that the crystallization rate and the degree of crystalliza-tion of PEEK matrix are jncreased．
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发布时间：2021-03-19 - 摘要：Chemical oxidative polymerization of toluidine(o-, m-, p-) in the acid solution has been studied, and soluble poly-o-toluidine(PoT) and poly-m-toluidine(PmT) are characterized by IR,1H NMR and elemntal analysis. It is shown that the pH value of the polymerization solution affects not only the colour and yield, but also the structure and properties of polymers obtained. The o- and m-toluidine have sinilar polymerization behavior in terms of its dependence on oxidant concentration,but the p-toluidine does not. IR spectrum reveals the existence of 1,2,4-substituted benzene(B),(B)NH(B), and quinone ring(Q)in the mole-cular chain of neutral PoT and PmT. The mole ratio of B to Q is about 3:1 according to 1H-NMR and elemental analysis. Based on the above results, a possible polymerization mechanism of toluidine(o-,m-,p-) in the acid solution is proposed.
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发布时间：2021-03-19 - 摘要：The compatibility and hydrogen bonding between PBT and PA6 segments's in amorphous poly(butylene terephthalate) (PBT)polycaprolactam (PA6) block copolymers, have been proved by differential scanning calorimetry, dynamic mechanical analysis, infrared spectrum analysis and small angle X-ray scattering.
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发布时间：2021-03-19 - 摘要：Thermal peroxidized PP films and PE films were graft copolymerized with a light stabilizer,2,2,6,6-tera-methyl-piperidinyl-merhacrylate (MTMP), by UV-irradiation in the absence of sensitizers in order to improve the photostability of films. The influence of various factors, including the thermal peroxidizing time, irradiation time, monomer concentration and the type of solvents, on the grafting content of the peroxidized films was examined. It is shown that the graft copolymerization can not take place in common organic solvents except ketones,and the photostability of either grafted PP or grafted PE film increases greatly com-pared with that of the ungrafted film.
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发布时间：2021-03-19 - 摘要：The study shows that the reverse flow method to be sutiable for determination of system-induced zone broadening in TFFF. This broadening effect is dependent on retention volume Vr, but independent on the structure of sample eluting with identical Vr Under proper circumstance, the reverse flow method may be used for estimation of the molecular weight distribution of polymer samples.
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发布时间：2021-03-19 - 摘要：Carbon-13 Nuclear Magnetic Resonance (NMR) technique is used to study the microst-ructure of a series of chlorinated atactic polypropylene. Results show that the chlorination occure mainly in the way of mono-substitution up to a chlorine content of 52.84% by weight. The mean relative reactivity of three kinds of protons towards chlorination is R(CH)>R (CH2) >R(CH3), and the chlorine atoms are distributed homogeneously in the molecular chain. It is shown that the chlorination of polypropylene could be influenced by three struc-ture factors: C-H bond energy,stability of the macromolecular free radical and configuration of the molecular chain.
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发布时间：2021-03-19 -
STUDY ON THE COPOLYMERIZATION OF PROPYLENE AND ETHYLENE WITH A SUPPORTED TITANIUM CONTAINED CATALYST
摘要：The random copolymerization of propylene and ethylene with a supported titanium contained Ziegler-Natta catalyst has been studied. The effects of temperature, Al/Ti molar ratio, concentration of electron donor and hydrogen on the copolymerization reaction were described. The regular variations of the copolymerization rate and the viscosity of copolymer were discussed. The composition, sequence of copolymer were measured by 13C-NMR. Two maxima of the curve of copolymerization rate vs feed ratio of comonomers at 10 mol% of pro-pylene and ethylene respectively have been observed. DSC curves display that both of melt-ing temperature and crystallinity of the copolymer decrease with increasing of the molar frac-tion of ethylene and the peak shape becomes lower and broader in the range of 0-10 mol% of ethylene ratio at 128/116℃,which are attributedto the formation of two different sequen-ces in the random copolymer chains.- 3
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发布时间：2021-03-19 - 摘要：Polarizing microscopy and differential scanning calorimetry (DSC) were used to study the effect of carbon fiber on the crystallization of polypropylene (PP). It is shown that the surface of carbon fiber displays a high propens ity to nucleate PP crystallization. The nuclei density at the surface of carbon fiber is much higher than that in the bulk area, and the resulting radial growth produces a type of transcrystalline structure, and the characteristic temperature of crystallization increases with carbon fiber concentration. By the study of the crys-tallization kinetics it is concluded that the crystallization in spherulitic in nature,carbon fiber promotes the crystallization of PP by decreasing it's crystalline surface free energy.
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发布时间：2021-03-19 - 摘要：In this paper a new．approximate．method，which is called "The Conformational Counting Method”，for estimating the conformational entropy of polymer chains has been proposed．The method is applied to random self-avoiding walks on simple cubic lattice．In the range of chain step number n=7～19 the entropy data obtained by this method are consistent perfectly with their precise value and the deviation is smaller than 0.04％ (sample sizes～2，ooo)．In the range of n up to 26 of chains confined in a cubic box of side length 2 the entropy data are consistent very good also with their precise value obtained bv means of directly counting all conforma-tions．The deviation is smaller than 0.6％ (sample sizes～2，000)．In the range of n up to 2，100 of free chains,the entropy data confirm the renormalization group prediction：S/K=nlnμ+(γ-1)lnn+In Co where k is Bottzmann constant，μ=4.6838，γ=7／6 and Co=1.17．For all chain step number deviations are negative and within 0.8％ (sample size8～300)．The way to improve the accuracy is suggested.
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发布时间：2021-03-19 - 摘要：The photo-induced copolymerization of the complex of 4-vinylpyridine and ZnCl2 (4-VP)2ZnCl2 (M1) as an electron-accepting monomer with the electron-donating monomer styrene (M2) was studied under the irradiation at 365 nm. The charge-transfer complex between them absorbs the light and then produces initiating radicals. The reactivity ratios were measured to be r1=2.04 and r2=0.24. The effect of the polarity of the solvents on the copolymerization and the photo-induced copolymerization of (4-VP)2 ZnCl2 with other electron-donating mono-mers were also investigated.
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发布时间：2021-03-19 - 摘要：Using secondary derivative spectroscopy and Fourier self-deconvolution techniques, the resolution of overlapping different carbonyl stretching components has been enhanced and a new carbonyl stretching componont at 1715 cm-1 has been found. Spectra subtraction and curve fitting have been used to follow the changes in intensity of these three components in Amide I region of polyurethanes during thermal treatments. The change in intensity of the newly found 1715 cm-1 component as a result of thermal treatment is quite similar to the be-havior of the free carbonyl stretching component (1730cm-1) and generally opposite in be-havior to the strongly hydrogen bonded one (1702-1705cm-1) and therefore,can be assig-ned to dissordered interphase region.
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发布时间：2021-03-19 - 摘要：A series of different substituted ureas were evaluated as latent accelerators in the curing of dicyandiamide-cured epoxy resin by DSC, TBA and rotation viscometer techniques. Experimental work revealed that the accelerating effect of the substituted ureas was promoted with the decrease of the magnitude of the a substituents, whereas the nature of the substitu-tents on the β and γ locations has no disturbance on the accelerating level. Comparis on of varionus ureas shows 4, 4'-bi(N, N-dimethyl) urea diphenyl methane and 2,4-bi(N,N-dime-thyl) urea toluene to be the most effective among the accelerators evaluated in this work.The temperature required for cure completion of dicyanidimide-cured bisphenol A epoxy resin was decreased from 170℃ to 130℃ using these optimized accelerators. The storage life of epoxy formulation with 3phr accelerators at 30℃ might be delayed to over three months based on the extrapolation from Arrhenius plots and viscosity-storage time curves.
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发布时间：2021-03-19 - 摘要：A study has been made of the effect of thermal history on melting behavior of poly (ether-ether-ketone)(PEEK) and its carbon fiber composites (APC-2) br using differential scanning calorimeter (DSC)．The two samples crystallized and annealed between 200 and 315℃ from the rubbery state or from the melt state exhi-bited a small endotherm peak (T'm) at approximate 10 to 20℃ above the crystalliza-tion and annealing temterature (Tc) and a large endotherm peak (Tm) at 335 to 345℃．The small endotherm peak was attributed to the melting and recrvstallization of the unperfect crystals formed at the Tc．The large endotherm peak was attributed to the melting of the perfect crystals．The results of our study showed that the Tm depe-nded linearly on Tc．The "thermodynamic equilibrium melting point" calculated acco-rding to the literature which is defined bv the intersection temperature of T'm as a function of Tc with the T'm = Tc line．The results of our study demonstrated also that carbon fiber in the composites has a strong effect of perfection on the crystals of PEEK matrix，so that the melting point of composites is higher than that of PEEK resin itself．
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发布时间：2021-03-19 - 摘要：Sequential poly (vinyl acetate)/poly (methyl acrylate) interpenetrating polymer networks (PVAc/PMA-IPNs) were synthesized. The crosslinking agent of PVAc and PMA is diallyl succinate (DAS) and divinylbenzene (DVB), respectively. When the plrecentage of DAS added is small, grafting reaction contributes crosslink level of PVAc obviously. Dynamic mechanical results shows that the important influence on, phase separation in PVAc/PMA-IPNs, is from the temperature of synthesis and sol-gel transition during the process of IPNs'pre-paration.
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发布时间：2021-03-19 - 摘要：The Mark-Houwink constants of poly (1-octene) in THF at 25℃ were evaluated from GPC and [η] of broad distribution samples. Two methods were used: calculation of K and a from the method developed by weiss and from the linear relation between in In[η] and InMx made by Goldwasser. More reliable results were obtained with the latter method. Determination of the molecular weight was made with the light scattering method, which gave Mw value close to that obtained from GPC. Then the Mark-Houwink equation for poly(1-octene) is [n]25℃THF×10-4M0.625. The effects of polymerization conditions on molecular weight distribution were studied with GPC. When AlEt3 was used as cocatalyst,the distribution was bi-modal. The change of alkyl aluminiums caused greater effect on the distrbutions than the cha-nge of TiCl3 strucure.
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发布时间：2021-03-19 - 摘要：Polymerization of acrylamide (AAM) initiated with eerie ion-acetanilide (AA) and its derivatives binary systems has been studied. It was found that cerie ion alone and eerie ion coupled with AA, acetyl p-toluidine (APT), acetyl p-chloroaniline (APCA), acetyl p-nitro-aniline (APNA), N-methyl acetanilide (NMAA), benzanilide (BA), N-methyl benzanilide (NMBA) and N-p-tolylbenzamide (NTBA) could initiate AAM to polymerize, The activity of amide on polymerization rate was investigated. The descending order of Rp was PAT》AA APCA>BA>NMAA>APNA. The overall energy of polymerization Ea, the kinetic equation of polymerization and the end group of polymer obtained were determined respecti-vely.
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发布时间：2021-03-19 - 摘要：In this paper the process of the thermal stabilization of polyacrylonitrile (PAN) fibres pretreated with cuprous Chloride (CuCl) have been studied in air and nitrogen atmosphere by in-situ infrared spectroscopic method. From the results is was found that the rate of cyclita-tion proceeded furiously at 240-300℃ region and is much faster than the rate of dehydro-genation. It may be inferred that for CuCl treated PAN fibres the aromatization of the structure de veloped extensively and the formed structure more stabilized. It was shown that the incorporation of Cu Cl in the PAN structure enhances the rate of cyclization byabout 1.4 time in air (260℃) and by about 43% in nitrogen (340℃).
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发布时间：2021-03-19
Research Article
- 摘要：The number average molecular weight Mn, second virial coefficient A2 and intrinsic viscosity [η] were measured for unfractionated and fractionated samples of a lacquer polysaccharide from Vietnam by dynamic membrane osmometry and vlscosimetry. The aqueous 0.5MKCl/10% cadoxen was chosen as a solvent, which not only rapidly dissolved the polysaccharide to form a particularly stable solution, but also did not destroy the regenerated cellulose membrane used for osmometry. The Mark-Houwink equation and A2~ Mn relationship for the polysaccharide in aqueous 0.5M KCl/10% cadoxen at 30℃ were found respectively to be [n]=1.44×10-2M0.56n and A2=0.142Mn-0.48.This implies that branched polysaccharide in the aqueous solution takes a fairly compact coil conformation.
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发布时间：2021-03-19 - 摘要：Very thick slurry of sodium sulfohexyl methacrylate (SSHMA) with little amount of water was plasma-initiated and polymerized. The mechanism and kinetics of plasma-initiated polymerization of SSHMA were preliminarily studied. The existence of macromolecular "living" chains were ascertained by experiments. Thus, SSHMA-acrylic acid block copolymers were obtained by adding acrylic acid to livingSSHMA segments. The ESR results suggest that propagating radicals CH2C(CH3)CO-O(CH2)6SO3Na might be present in the SSHMA system initiated by plasma. It was found that no"living"chains were present in the SSHMA system initiated by either UV light or radical initiators under the same conditions.
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发布时间：2021-03-19 - 摘要：2-Hydroxy-3-morpholinopropyl methacrylate( HMPMA) has been synthesized from mor-pholine with glycidyl methacrylate. From the rate equation and the overal activation energies of polymerization of HMPMA initiated with lauroyl peroxide, the redox initiation mechanism was suggested. The photopolymerization of HMPMA sensitized by various aryl ketones was investigated.
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发布时间：2021-03-19
Research Bulletin
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