最新刊期
卷 ， 期 1 ， 1999
- 摘要：Cationic polymerization of 1,3 pentadiene (PD) by trimethylsilyl trifluoromethanesulfonate ((CH3)3SiOSO2CF3) in combination with SbCl3 were carried out in n hexance at 30℃. Addition of SbCl3 into the (CH3)3SiOSO2CF3 induced PD polymerization. The polymer yield increases from 55% to 80%, the polymerization is accelerated 24 times and the molecular weight of polymer is 17 times. Various ketones were used to mediate the initiating system (CH3)3SiOSO2CF3/SbCl3, the more bulky the ketone is,the higher yield and molecular weight are obtained.The 1H-NMR and the IR show that the polymerization of PD was initiated by the SbCl3 in complexation with trific acid (HOTf) resulting from hydrolysis of (CH3)3 SiOSO2CF3 adventitious water.
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发布时间：2021-03-19 - 摘要：The influence of a nucleating agent,a nucleation promoter and their mixture on the crystallization of poly(ethylene terephthalate) (PET) from melt state was studied by different characterization techniques including the measurements of the crystallization temperature in a non isothermal cooling process,halftime in an isothermal crystallization process and the specific surface free energy for nucleus formation during crystallization.The nucleating agent used was a derivative of sodium benzoate while the nucleation promoter was a sort of low molecular weight ester-ether copolymer.It was found that the nucleating agent could promote the nucleation and crystallization of PET,reducing the specific surface free energy for nucleus formation during crystallization.However,the nucleation promoter had little influence on the nucleation and crystallization rate of PET in the high crystallization temperature range.The nucleation promoter may slightly increase the degree of crystallinity of PET,when the mixture of the nucleating agent and the nucleation promoter was used,the crystallization behavior of PET from its melt state was mainly controlled by the nucleating agent.
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发布时间：2021-03-19 - 摘要：Propylene polymerizations in the presence of various monocyclopentadienyltitanium compounds and methylaluminoxanes(MAO) have been investigated. It was found that by substituting methyl group for hydrogen in the cyclopentadienyl ring, the titanocene catalyst affords a polypropylene with increasing molecular weight by one order of magnitude. Residual AlMe 3 content in MAO has an determinative effect on catalytic activity for the propylene polymerization. An excess of AlMe 3 in the catalyst system, such as 25% AlMe3 inMAO,hinders the polymerization by reducing the Ti species to inactive lower valent states.The effects of molar ratio of MAO to Ti complex,polymerization temperature and monomer pressure on catalytic activity and molecular weight of the products are studied in detail.Tbus,atactic polypropylene with the molecular weight range of 20～100×104,much higher than that prepared by unsubstiuted cycloopentadienyltitanium complex has been synthsized by η5-pentamethylcyclopentadienyltitanium tribenzyloxide/MAO catalyst.The atatic polypropylenes exhibit excellent elasticity.
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发布时间：2021-03-19 - 摘要：Chemical microstructure of the atactic polypropylenes prepared with cyclopentadienyltitanium tribenzyloxide/methylaluminoxane and pentamethylcyclo pentadienyltitanium tribenzyloxide/methylaluminoxane catalysts has been investigated by 13C-NMR spectra.Both catalysts give the polymers with similar stereo structure distributions.A satisfaction of Baernoullian statistics,by mr/(2mm+mr)+mr(2rr+mr)≈1,indicates that the propylene polymerizations are stereochemically obedient to a chain end control.The present polymers are regioirregular and contain a nonnegligible proportion of propylene units arranged in head to head and tail to tail sequences which can be observed in the methine carbon regin of the 13C-NMR spectra.From a statistical analysis of the regiotriad distribution,it was found that polypropylenes with regioblock structure can be produced with the catalysts.Considering a binary copolymerization of 1,2-orientation monomer and 2,1-orientation monomer,the reactivity ratios,r1 and r2,were calculated.The relations of r1>1,r2>1 and r1r2>>1 indicate that the incoming monomers tend to insert into the metalcarbon bonds with the same orientation as the end units.By substituting methyl group for hydrogen in the cyclopentadienyl ring,the titanocene catalyst affords a polypropylene containing shorter regioblocks.The of the regioblocks increases with reducing the polymerization temperature.
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发布时间：2021-03-19 - 摘要：A series of polyurethane (PU), prepared by using uretonimine modified pure 4,4' diphenylmenthane diisocynate (MDI), and vinyl ester resin (VER) simultaneous interpenetrating polymer networks (SINs) with different compositions have been synthesized. Based upon the DSC, SEM and WAXD observation, the experimental results showed that the chemical bonds between the two networks had great influence on the structure, morphology and mechanical properties of these SINs. For PU/VER SIN in which there are no chemical bonds between the two networks,it is a thermodynamic incompatible system and exhibits phase separation morphology.This is probably related with the different formation rates of the two networks and mixing conditions for forming such SINs.For PU/VER SIN having chemical bonds between the two networks,the compatibility between the two phases and mechanical properties of SINs increased appreciably.Furthermore,the morphology and mechanical property of such SINs are also related with the mixing conditions,i.e hand mixing and reaction injection molding,for forming these SINs.
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发布时间：2021-03-19 - 摘要：The paper presents the preparation of poly(glycidyl methacrylate)(PGMA) beads approaching to monodisperse particle size in diameter from 1 to 8μm by using dispersion polymerization.The dispersion medium used is certain alcohols or mixtures of alcohols with other solvents,the initiator is azo bis isobutyronitrile or benzoyl peroxide,the stabilizer is poly(vinyl pyrrolidone).The effects of various polymerization parameters on particle size of reaction products were systematically investigated.The experimental results show that particle diameter of PGMA beads is increased with increase of reaction temperature,initiator concentration and medium solvency,and the diameter tends to decrease with increase of stabilizer concentration within the limits of particle distribution.The dependence of PGMA particle size on monomer concentration is a reversed parabolic curve having a minimum of particle size at a monomer concentration of 10wt%.The proper conditions for preparing uniform PGMA beads of 1～8μm have been described in the report.
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发布时间：2021-03-19 - 摘要：A novel poly(ether ketone ketone) containing the phthalazinone moiety (PPEKK) was prepared by the nucleophilic displacement reaction of 4 (4 hydroxyphenyl) (2H) phthalazin 1 one with bis 1,4 (4 chlorobenzoyl)benzene. The polymer was studied by FT IR, 1H-NMR,DSC,TGA,X ray diffraction. It has been proved that PPEKK was a amorphous plastics with high glass transition temperature ( Tg=245.6℃) and good thermal stability, It was soluble in some solvents.
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发布时间：2021-03-19 - 摘要：Polystyrene supported N benzyl N methyl aminopyridine(BMAP) was prepared through chloromethylated polystyrene beads (made in the chemical plant of Nankai University in Tianjin, Cl%:6.49,DVB:2%) treated with 4 aminopyridine and dimethyl sulphate. All the reaction were performed under efficient stirring and protection of N 2. BMAP was determined by elementary analysis, FTIR and MAS 1H-NMR. BMAP is a useful catalyst for acetylation of linalool. Some experimental paramaters (anhydride and alcohol molar ratio, reaction temperature,reaction time,etc) were discussed.The conversion of linalool is over99%,toal esters is about 95% and Linalyl acetate is above 60%.There are advantage in comparison with literature:reaction time shorter,price lower and the synthesized BMAP more active.
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发布时间：2021-03-19 - 摘要：The synthesis and free radical polymerization of the novel methacrylate monomer containing para methoxyphenyloxycarbonylazobenzene group (AZO2) and the methacrylate monomer containing para methoxyphenyloxycarbonylbenzene group (MAPB2) are described.The novel azo monomer and the polymers were characterized by 1H-NMR,IR,UV Vis,elemental analysis,GPC,TG DTA,POM and X ray diffraction techniques.The polymers obtained from the copolymerization of AZO2 and MAPB2 are proved to be random copolymers and all of the polymers show relatively good thermal stbility.In addition,the azo monomer and the polymers exhibit nematic liquid crystalline textures and the temperature range of liquid crystalline behavior of the polymers broadens with increasing the azo content of the polymers.
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发布时间：2021-03-19 - 摘要：In view of that polyesterification reactions of diols with some aryl diacids consists of the non homogeneous and homogeneous reaction stages,two equations were proposed for calculation of the solubilities of aryl diacids in reaction mixtures and of the “clear points” of reactions,respectively.On the basis of the two equations,the kinetic model proposed by Chen and Wu for self catalyzed polyesterification reactions was modified into two rate equations which were used for the non-homogeneous and homogeneous reaction stages,respectively.The two rate equantions fitted the exoerimental data well,as was confirmed by the reaction of bis(4-carboxyphenyl) phenyl phosphine oxide with ethylene glycol under constant reaction temperatures of 180～197℃ and at different ratios of diol to diacid,whose rate constant and activation energy were calculated.The reaction rate constant was affected by temperature according to Arrhenius'law.The results of application of the two calculation equations of solubility and clear point and of the two rate equations shows that these equations were reasonable.
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发布时间：2021-03-19 - 摘要：Interpenetrating polymer networks based on polyurethane and epoxy based polymer containing phenylazo benzothiazole (BT) chromophore groups were synthesized.Crosslinked polyurethane was obtained by the reaction between (2 hydroxypropyl acrylate BT 2 methacrylate) copolymer and phenol capped NCO terminated BT 1,whereas crosslinked epoxybased polymer was formed by reaction between epoxy containing BT and BT containing aniline.The IPNs were synthesized by carrying out the above two reactions simultaneously,and were characterized by gel content,IR spectra and differential scanning calorimertry.The IPN shows two Tg at 142℃ and 170 ℃.Thin,transparent poled films of the IPN were prepared by spin-coating,followed by thermal curing and corona poling at 160℃ for 1h.The second-order nonlinear optical properties of the poled films were studied by a visible light absorbance measurement according to the one-dimensional rigid oriented gas model.Long-term stability of the dipole alignment at 120℃ was demonstrated for the IPN.
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发布时间：2021-03-19 - 摘要：Polyvinyl alcohol (PVA) can be degraded by bacteria from various soil sources and its structure is somewhat similar to that of starch.It is an available way of blending polyvinyl alcohol (PVA) with starch to develop biodegradable materials.The high speed stirring is a suitable method while blending of PVA and starch to prepare the biodegradable materials with better properties required.The effect of high speed stirring on the properties of starch/PVA blend solution was studied by means of spectrophotometry,microscopy,molecule weight analysis and rheometry etc.The experimental results indicate that changes are found on the chains of PVA and starch after conducting high speed stirring,which causes a modification in the properties of starch/PVA blend solution.The degrading effect of high speed stirring on starch and PVA agrees to the common mechano-chemical degrading feature.The high speed stirring breaks the side chain of starch and eventually increases the amylose content in starch solution.The high speed stirring also lowers the Mw and widens the Mw distribution of PVA. The dispersion of starch in PVA is improved by high speed stirring and the interaction between starch and PVA is strengthened,resulting in an improvement of the mechanical properties,transparency and water-repellence of starch/PVA blend film.
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发布时间：2021-03-19 - 摘要：Based on the detailed researching in the curing reactivity,reaction mechanism,dynamic mechanical behavior and impact strength for E51/dicy curing system modified with LCEU PPG containing both the flexible spacer chain and rigid liquid crystal unit chain,the morphology of the fracture surface was observed by SEM.The relationships between the morphologies and dynamic mechanical behavior,impact strengths were also discussed.The results reveal that there exist two phase microstructure for the modified curing systems.This leads to the significant improvenment in impact strength.
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发布时间：2021-03-19 - 摘要：The peculiarities of orientation in a chiral side chain liquid crystalline polymer by action shear stress were studied.The mesophases and phase transition temperatures of chiral side chain LCP Ps 11 are:crystalline Sc * phase (90℃), Sc * S A phase (98℃) an S A isotropic phase (117℃), determined by DSC and POM with a hot stage. The polymer Ps 11 shows typical focal conic texture is S A phase and straited focal conic texture in twisted Sc * phase. A typical banded texture with parallel bands extended in a direction perpendicular to the shear direction can be observed during quenching from the sheared melt at the temperature of SA phase.The width of bands is about 1μm.Infrared dichroism of the oriented film reveal that the orientation of the side chains containing mesogen tend to be normal to the shear direction in the oriented film,which means the smectic layers tend to parallel to shear direction because of mesogenic director normal to layer.X-ray diffraction pattern indicates that the bilayered superstructure of smectic phase,which can be attributed to an antiferroeletric ordering exist in this polymer.The relaxation behavior of the oriented film exhibits that orientation history is useful is useful for the growth of smectic layer and ordered focal-conic texture can rapidly be formed in the oriented film during the heat treatment.
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发布时间：2021-03-19 - 摘要：The kinetics of isothermal crystallization has been studied for Na+,Mn2+ and Ca2+ ionomers based on maleic anhydride graft polypropylene(PP g MAH) by DSC,compared with pure PP and PP g MAH.Avrami equation was valid for analyzing the experimental data.The fact that Avrami exponents close to three for all the samples implied the mode of PP crystallization was not changed by the solid graft modification.The introduction of ions increased the crystallization rate(characterized by the reciprocal of the half-life of the crystallization,t-11/2) dramatically.At the same time,the increase of neutralization also increased the crystallization rate.The reducing of the interfacial free energies of the side surfaces of the nucle σe,calculated from Hoffman theory,bu the anhydride group and ions had the same trend with the results of Avrami equation.
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发布时间：2021-03-19 - 摘要：Two novel dendritic polymerizable monomers with multi hydroxyl groups at the arch deck and a vinyl group at the end of the wedge have been synthesized,their polymerization reactions by free radical initiation have been investigated.The results indicate that these molecules generally behave like those monomers containing allyl groups,which leads to a conclusion that the polymerization activities of the double bonds are not influenced by multiple hydroxyl groups nor their positions on the wedge.Dendron 1 with an allyl-ether end can be copolymerized with electron poor olefins such as acrylonitrile,but it does not homopolymerize,Dendron 2 with an methacrylate end undergoes both homo- and co-polymerization rapidly.These multi-hydroxyl wedges are water-soluble molecules and they build a new type of polymers consisting dendritic units hanging on a flexible linear chain.Most of these polymers are also water-soluble.
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发布时间：2021-03-19 - 摘要：A series of thermotropic side chain liquid crystalline poly ω (4' methoxy 4 azophenyloxy)alkanoyl methacrylates (PMAAZO n,n =2,3,4,5,6) were prepared by the reaction of potassium methacrylate and 4 methoxy 4' (1 bromoalkoxy)azobenzene,then free radical polymerization in THF solution.Their structures were verified by 1H, 13C-NMR and IR spectra.The number average molecular weight (MW) of PMAAZO n were around 20,000,thus the effects of M W on the liquid crystalline (LC) properties were negligible.The LC behaviors of the polymers obtained were examined by DSC and optical polarizing microscope.Only one nenatic state for PMAAZOn,(n=2,3 and two LC states:one smectic and one nematic state for the polymers of n=5 and 6 were observed.As spacer length increased,glass transition temperature decreased.On the curves of △H and △S against spacer length,the lowest values appeared at n=3.The lowest stability of LC state was probably the result of odd-even effect and low decoupling.The odd-even effect on TNI of PMAAZOn was observed,and explained based on the placement of the mesogenic groups on relation to the polymer backbone.The physical aging process of the polymers would increase their TNI and decrease △HNI.
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发布时间：2021-03-19 - 摘要：Poly(isoprene b methyl methacrylate) block copolymer has been synthesized by rare earth coordination catalysts,which are composed of rare earth 2 ethyl hexyl phosphonates RE(P 204 ) 3 ,triisobutyl aluminum Al( i Bu) 3 and 1,2 dibromoethane DBE .It is found that the rare earth coordination catalysts are highly active for the block copolymerization of isoprene and methyl methacrylate.The diblock copolymer prepared has been characterized by DSC, 1H NMR and 13C NMR.The block copolymer has two glass transition temperatures at -75.6℃ and 129℃ corresponding to the isoprene block phase and the methyl methacrylate block phase,respectively.The microstructure of the diblock copolymer is a highly stereoregular.For the isoprene scgment in the diblock copolymer it mainly exists in the form of cis-1,4 addition.The content of cis-1,4 addition is 97% and of 3,4-addition is 3%.For the methyl methacrylatc segment it is mostly syndiotactic,which is 74% syndiotacticity,4% isotacticity and 22% heterotacticity.The n(ad) probabilities of methyl methacrylate units in the block copolymer are calculated,and it is showed that the methyl methacrylate segment obeys second order Markov statistics model.
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发布时间：2021-03-19 - 摘要：The paper dealt with the influences of the o,o' diallyl bisphenol A ether(DBAE) grafted low density polyethylene(LDPE g DBAE) as a compatibilizer on HDPE/PC blend system. The efficient compatible effects of LDPE g DBAE on HDPE/PC blends were confirmed through morphology observation, thermal and mechanical properties test, as well as crystalizing behaivor. Data showed that the HDT of the 65/35 HDPE/PC blend in the presence of 10phr LDPE g DBAE was 92℃ and tensile strength 30.2MPa, notched impact strength 29.8kJ/m2,while the HDT of the same composition blend with no compatibilizer was only 82℃ and tensile strength 27.3MPz,notched impact strength 15.5kJ/m2.The optimal concentration of the compatibilizer was 10phr and it was of benefit to improving properties of HDPE/PC blends with increasing the graft degree of LDPE-g-DBAE.
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发布时间：2021-03-19
Research Article
- 摘要：The combination method of bubble pressure and fluid permeability was used to determine the average pore size and size distribution of a polypropylene(PP) microporous film prepared by biaxial stretching.The flux average pore size rJ and a parameter R90 = r90/rJ were suggested to characterize the pore structure of a microporous films,especially when they are used as filtration membranes. r90 is the pore size corresponding to 90% integral flux along the integral flux/pore size curve.The polypropylene microporous film sample shows a narrow pore size distribution with R90=1.26 and the average pore size rJ=14.9nm.
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发布时间：2021-03-19 - 摘要：The coordination polymerization of ethyl vinyl ether conducted by using Ziegler Natta catalyst in the presence of C60 has been studied under certain conditions, i.e.Al/Ti=3.It has been found that the polymerization conversion increased with the increase of C60 added in the polymerization system.GPC results of the polymers obtained show that the molecular weight increased with the increase of C60 .The solubility and UV vis spectra of polymers indicate that C60 was covalently incorporated into the PEVE chains.C60-PEVE displays the fluorescence emission at 525nm with the exciting wavelength of 440nm at room temperature.Since C60 does not process fluorescence emission at room temperature,and there is no hetero-atoms on C60 and no chromophore other than C60 in C60-PEVE,it is reasonable to assign that the lessening of the high symmetry of C60 bonded to PEVE leads to the exhibition of fluorescence.
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发布时间：2021-03-19
Research Bulletin
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