最新刊期
卷 ， 期 4 ， 1992
- 摘要：The radiation-induced racemization and chain-scission of crystalline isotactic poly (methyl methacrylate) (i-PMMA) were studied with proton NMR, DSC and molecular weight(MW) determination. It is shown from MW results that the chain-scission reduces in crystalline phase. Its G-value is only half of that in amorphous region. NMR study on the radiation-induced change of stereospecific structure indicates that iso-PMMA transforms gradually into syndiotactic and atactic ones, similar to what happens in amorphous phase.However,radiation-induced racemi-zation in crystalline state is more remarkable than chain-scission reaction.Such an effect could be well explained with the effect of "cage"and steric hindrance on above-mentioned two reac-tion mechanisms,as we proposed before.Because of both reactions taking place within cystal-line region,the reduction of melting point of iso-PMMA with radiation dose is more remarkable.The G-value of the damage in crystalline phase estimated is 8.8,which is much higher than that in polyethylene.
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发布时间：2021-03-19 - 摘要：The polymerization of acrylonitrile (AN) in aqueous nitricacid initiated by "cage" vanadyl(IV) poly (oxime-imidodiacetate) (CPV)-thiourea (TU) system has been investigated. The overall rate of polymerization isRP = 10×108e-10.500 /RT[AN]1.0[CPV]1.0[TU]1.5[HNO3]3.0The length of the induction period (r) varies with the polymerization temperature and the substrate concentrations. It may be written as1/τ = 5.2×109e-12.800/RT[AN]1.0[CPV]1.0[TU]1.5[HNO3]3.0 These results suggests that the chain radicals are terminated via bimolecular reaction predomintately.Possibly,it is affected by the steric hindrance of the bulky polymer supporter.
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发布时间：2021-03-19 - 摘要：A novel type polymer-bound tridentate 2S-N ligand platinum complex, fumed silica-poly-γ-bis-N, N-(β-methylmercaptoethyl) amino propyl silsesquioxane platinum complex, has been synthesized from N, N-bis (β-methylmercaptoethyl) y-(triethoxysilyl) propylamine by hydrolysis of the monomer or cohydrolysis of it with dodecyltriethoxysilane and immobilization on fumed silica, followed by reacting with ponssium chloroplatinite in acetone under Ar atmosphere. It was found that they are efficient catalysts for the hydrosilylation of olefins with triethoxysilane. The influences of the nature of substrate,reaction temperature,the amount of complex used on the catalytic activity,as well as the recovery and reused property of them were investigated.
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发布时间：2021-03-19 - 摘要：By using interfacial synthesis, a series of new organo-Tin polyethers were prepared through dialkyl Tin dichlorides. Bis (-alkoxycarbonyl ethyl) Tin dichloride, reacted with diols, diph-enols and dithiols. These new polymers are cheracterized with molecular weight, IR and TG/ DTG. Part of the polymers synthesized was tested for their effect on the heat-stabilization of PVC resins. The result indicated that the new synthesized organo-tin polyethers can be used as heat-stabilizers for PVC products.
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发布时间：2021-03-19 - 摘要：The relation between the degree of polymerization and the type of initiation as well as the relation between the polymerization degree and the chain transfer for butadiene polymerization under molybdenum and iron catalyst systems were studied. Time graph was suggested to be used to determine the type of initiation if there exists chain transfer reaction. For slowly-initiated non-steady state polymerization, it was proposed that the main chain transfer be decided in the quasisteady state period. Identical results were obtained by using graphical integra-tion and the ratios of equal rates methods to deal with the adta. Theoretical analysis was presen-red to provide the feasibility of the ratios of equal rates method.
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发布时间：2021-03-19 - 摘要：In this paper the scaling behavior and percolation structure of spinodal phase separation in a binary polymer blend of poly (vinyl acetate) (PVAc) with poly(methyl methacrylate) (PM-MA) were studied by using light scattering and optical microscope techniques. Unmixing process was found to give the scaling law on the wave number of the dominant Fourier componen' of the fluctuation qm and on the maximum scattered intensity Im as given by qm-t-α and I-tβ The percolation structure was found in the phase separation process. The fractal dimension for 2d cluster of the spinodal decomposition can be obtained from microscope picture.The fractal dimension is about 1.64.
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发布时间：2021-03-19 - 摘要：The structure of ionic clustering for the membrane of perfluorosulfonate hollow fiber was studied by means of small-angle X-ray scattering (SAXS). The reflection peaks observed in the SAXS for fiber membranes at about 29 = 2° were attributed to the clustering of ions and the effects of ion-exchange capacity (IEC), cation species, water content and the drawing tensile on the diffraction peaks were investigated and discussed. The radii of the clusters and the numbers of ions in clusters were also calculated.
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发布时间：2021-03-19 - 摘要：In this paper, the dynamic mechanical property and the phase inversion of the polyurethane (PU)-polyvinyl(PVA) blend system were studied. It was found that the phase inversion bet-ween the contious phase and the disperse phase took place when PVA content reached the range of 30-50%. Furthermore, mechanical models were used to describe the modulus composition relation, the isochronal mechanical spetrum and the diffusion coefficient composion relation of the blends. The experiment data were within the theoretic prediction and respectively fitted the mo-dified Kerner model and combination Kerner model.
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发布时间：2021-03-19 - 摘要：Resonance Raman spectra of polyaniline (PAn) in different forms (base, doped, dedoped, reduced and oxidized) were determined. According to the spectral features and other experimental results, it was found that the molecular chain of the doped PAn consists of two kinds of N atoms and three kinds of aromatic rings with different charge distribution. The effect of the oxidation extent of the PAn chain on the doping efficiency was observed. Thus the "Four-ring BQ derivatives" model and corresponding doping reactions were proposed.
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发布时间：2021-03-19 - 摘要：Poly(n-Butyl Acrylate)/Polyurethane based on castor oil semi-SEN(PnBA/COPU) has been synthesized by simultaneous prepolymerization and characterized by TBA, SEM and tensile test. The results show that some mechanical propertjes,such as Young's modulus, tensile strength and elongation at break, increase synergistically at PnBA/COPU = 10/90, whereas the fracture energy shows the maximum at PnBA/COPU = 50/50. The semi-SEN is a partial compatible system and two-phase structure with domain size of about 800A is observed.The effect of morphology on the properties of the semi-SEN has been discussed.
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发布时间：2021-03-19 - 摘要：The Solvated Metal Atom Impregnation (SMAI) technique was employed to prepare D-72 resin supported and non-supported La-Ni and Ni catalysts. The results of XRD and magnetic measurements showed that La-Ni alloy was formed in La-Ni catalysts. The particle sizes of La-Ni alloy and Ni were very small, with average diameters 2O3 . The activities of D-72 supported catalysts were all greater than tose of non-supported catalysts in the hydrogenation of acetone and dia-cetone alcohol.
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发布时间：2021-03-19 - 摘要：The morphology of spherulites in nylon 1010 and its formation condions in isothermal crystallization have been studied by a polarizing microscope. When crystallized near and above the original melting temperature (Tm) of the sample, three kinds of negative nonringed spherulites, darker, brighter and with a positive ring, can be obtained. Between Tm and 195℃, nonringed positive spherulites will be formed. In a wide range of temperature, mixed nonringed spherulites and a few six-sectional, two-sectional, and asymmeteric four-sectional spherulites will be crystal-lized.Under 181℃ nylon 1010 is crystallized to form positive ringed spherulites.
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发布时间：2021-03-19 - 摘要：The crystallization kinetics and mechanisms of phase transitions for sequential block copoly-mers synthesized through polycondensation of the mesogenic group 2-methyl-p-phenylene di(4-chloroformyl) benzoate, 1, 10-decanediol (B) and poly (oxytetramethylene) glycol (C) have been investigated by using DSC, PLM, and WAXD. As a feed ratio of B/C( 10/90, 20/80, 40/60, 50/ 50, wt%), the values of Avrami exponent are n≈2 at all the feed ratios. The crystallization from isotropic melt experienced the stage of mesophase period.The crystallization either from isotro-pic melt or from mesophase has the same mechanism including nucleation through aggregation of orientational segments and the two dimensional crystal growth. The flexible block of poly(oxyse-tramethylene) glycol has a significant influence on the structure formation. It is worth to indi-cate that ca. the ratio 20/80 there a lower Bk value and a larger entropy change △Si during me-sophase to isotropic melt transition.
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发布时间：2021-03-19 - 摘要：PET/PHB copolyesters made from poly(ethylene terephthalate) (PET) and p-acetoxyben-zoic acid represent a kind of copolymers whose sequence structure is more complicated compared with the general binary copolymers. Based on the statistical analysis on sequence distribution of the copolyesters, a parameter, Bq, has been proposed to describe the degree of randomness of the copolyesters. It has been shown that the sequence distribution of the copolymer with Bq = b can be evaluated by comparing with the sequence structure of the general copolymer whose degree of randomness,B equals b.
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发布时间：2021-03-19
Research Article
- 摘要：A novel polyphenylquinoxaline ultrafiltration (UF) membrane prepared by a phase inversion method was reported in this paper. The effects of some factors in preparation on membrane performance, such as temperature and duration of heat-treatment, and polymer concentration, were studied. The pure water flux and retention of bovine serum albumin (BSA) and chymotrypsinum (CMP) used as ball standard matters by membrane have been quantitatively determined. The morphological structure of polyphenylquinoxaline UF membrane was observed by SEM. The results of experiments showed that the membrane exhibited better permeability and high selectivity,partcularly useful for the seqaration of BSA. When suitable preparing condi-tion were employed,the membranes showed good strength,high hydrolytic stability and high heat-resistant qualities. The upper limit of working temperature could reach 120℃.
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发布时间：2021-03-19 - 摘要：A kind of functional polymeric microspheres with weak anion exchange group of diethylaminoethyl (-DEAE) with particle diameter mere than 5 micrometers, as well as narrow dispersion in diameter, has been synthesized with moncmers of diethylaminoethyl methacrylate (DEAE-MA), vinyl acetate (VAC) and divinylbenzene (DVB) initiated by 2,2'-azo-isobutyronitrile (AIBN) at 65℃ for 10hr. The effects of reaction condition, such as components ratio of the reaction system, polymerization temperature and time on the diameter and distribution of particle diameter have been studied.
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发布时间：2021-03-19 - 摘要：Dynamic mechanical properties of different amine or zinc, barium ions neutralized sul-fonated butyl rubber ionomers were studied. The results showed that glass transition temperature, Tg1 and Tg2 of amine neutralized ionomers were lower than those of metallic ionomers and temperature range of the rubber plateau on the storage modulus vs temperature plot was narrower. E' of the rubber plateau for most amine neutralized ionomers was lower than that of zinc neutralized ionomers plasticized with zinc stearate. With increase of steric hindrance of steric hindrance of amine the temperature range for the rubber plateau became narrow and the height of the loss peak at higher temperature increased. Dynamic mechanical properities of blends of the zinc ionomer with polypropylene,high density polyethylene or SBS showed that Tm increased and Tg1 decreased with increase of polypropylene or polyethylene,while Tg2 changed only slightly Tg1 decreased with increase of SBS content. Decrease of Tg1 is attributed to the mixing of the matrix of ionomer ocntaining ion pairs with amorphous part of the other poly-mer,caused by enhanced compatibility due to physical interpenetrating networks.
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发布时间：2021-03-19 - 摘要：The purpose of this paper is to study the synthesis chemistry of supported Ziegler-Natta catalysts for polypropylene．Four kinds of catalysts were made，the first one (catalyst-A) from MgCl2-A solution containing MgCl2，EH(2-ethylhexanol) and PA (phthalic anhydride) dis-solved in decane；the second one (catalyst-B) from MgCl2-B solution containing MgCl2，EH and TBT (tetrabutoxy titanium)；the third one (catalyst-C) from MgCl2-C solution containing MgCl2，EH，PA and TBT；the fourth one (catalyst-D) from MgCl2-D solution containing MgCl2 and EH．The activity of catalysts varled in the order；B>C>A>D．Both activity and stereospecificity of catalyst-D ad'e very low．Catalyst-A and Catalyst-B have the same stru-ctures characterized bv X-ray diffraction．A mechanistic scheme for the variety of reactions that occur during the preparation of the final catalyst is proposed by analysis of IR spectra．The catalyst-B has about 60％ more activity and 2％ less stereospeci -ficity as catalyst-A．The pre-sence of BuO-group which has a less hindrance for monomer inserting has been identified as an improver of catalyst activity．The role of phthalic anhydride has been discussed in detail．Some“mono-esters”generated from the reaction between PA and ROH improved catalyst pro-perties．When PA was added during the preparation of catalysts，the finished catalyst produces polypropylene not only in high activity，but also in much better stereospecificity．
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发布时间：2021-03-19 - 摘要：The differential equation, which was proposed by us in previous paper, was applied to analysis of the DSC curves of poly (etkylene terephthalate) with several constant heating or cooling rates. The parameters characterizing the rate and the mechanism of crystallization can be derived by using present method. The results of the isothermal and the constant heating and cooling rate tests were illustrated.
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发布时间：2021-03-19 - 摘要：A polymerizable aromatic tertiary amine N-(2-methacryloyloxyethyl) -N-methyl-p-toluidine (MEMT) was synthesized and characterized by elemental analysis, IR and 1H-NMR spectra. MEMT in conjunction with organic peroxide such as benzoyl peroxide (BPO), lauroyl peroxide (LPO) formed a redox initiator. The overall activation energy of MMA polymerization using BPO/MEMT as initiator was evaluated to be 43.1 KJ/mol, which was much lower than that of BPO alone (E. = 85.8 KJ/mol). The rate equations of MMA polymerization were determined as follows.
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发布时间：2021-03-19 - 摘要：The Crystallization of constrained and fre oriented amorphous PET films were studied by using density, birefringence and stress measurements. It has been shown that depending on the birefringence of original sample, the effect of fixing two ends of samples on the Crystallization rate shows different behavior. For amor hous PET film with high birefringence the Crystallization rate of constrained sample is faster. For oriented amorphous PET with very low birefringence the Crystallization rate of free sample is faster.
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发布时间：2021-03-19
Research Bulletin
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