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1992 Volume 10 Issue 2
1992, 10(2): 99-106
Abstract:
The relationships between the properties of PVC-MBS polyblend and of the MBS multiphase structure and between the MBS structure and polymerization parameters are studied theoretically and experimentally. MBS resin synthesized from the molecule design principle is suitable to prepare PVC-MBS polyblend with good transparency and high impact strength.
The relationships between the properties of PVC-MBS polyblend and of the MBS multiphase structure and between the MBS structure and polymerization parameters are studied theoretically and experimentally. MBS resin synthesized from the molecule design principle is suitable to prepare PVC-MBS polyblend with good transparency and high impact strength.
1992, 10(2): 106-112
Abstract:
The copolymerization of l-octene with styrene catalyzed by rare earth coordination catalysts has been studied for the first time. Some features and kinetic behavior are described. The overall activation energy of the copolymerization was 22.2 KJ/mol and the copolymerization rate could be expressed as Rp=Kp [Nd] [M]2. (=1.68×10-3L2/mol2. S, 50℃, [Oct]/[St]=1). The catalytic activity of various rare earth elements in Ln (naph)3 for the copolymerization was compared and shows the following sequence:Dy,Y,Yb>Ho>Sm,Gd,Nd>Pr>Ce>La>Tm.Both monomers of 1-octene and styrene in the copolymerization by Nd(naph)3-AlEt3 have the tendency of constant proportion copolymerization.The structure of the copolymers was studied by 1H-NMR.
The copolymerization of l-octene with styrene catalyzed by rare earth coordination catalysts has been studied for the first time. Some features and kinetic behavior are described. The overall activation energy of the copolymerization was 22.2 KJ/mol and the copolymerization rate could be expressed as Rp=Kp [Nd] [M]2. (=1.68×10-3L2/mol2. S, 50℃, [Oct]/[St]=1). The catalytic activity of various rare earth elements in Ln (naph)3 for the copolymerization was compared and shows the following sequence:Dy,Y,Yb>Ho>Sm,Gd,Nd>Pr>Ce>La>Tm.Both monomers of 1-octene and styrene in the copolymerization by Nd(naph)3-AlEt3 have the tendency of constant proportion copolymerization.The structure of the copolymers was studied by 1H-NMR.
1992, 10(2): 113-118
Abstract:
The carbon-13 spin-spin relaxation times of fluorine-containing ionomers are measured and motional correlation times τo and τd are calculated by using VJGM model . The results show that the motions of polymer main chain in ionomers become more difficult with increasing of ionization degree and contents of functional group, and depend on the fine structures and stability of ionic microdomains.
The carbon-13 spin-spin relaxation times of fluorine-containing ionomers are measured and motional correlation times τo and τd are calculated by using VJGM model . The results show that the motions of polymer main chain in ionomers become more difficult with increasing of ionization degree and contents of functional group, and depend on the fine structures and stability of ionic microdomains.
1992, 10(2): 119-126
Abstract:
Poly (ethyleneglycol monomethylether) methacrylate (PEGMM)was synthesized by means of the reaction of methacrylyl chloride with sodium monomethylpolyethyleneglycoxide and was characterized by FTIR, 1H-NMR,and ultraviolet spectrometries. A series of poly (vinyl alcohol)-graft-PEGMM (PVA-g-PEGMM )and methyl methacrylate-PEGMM copolymer (PMMA-PEGMM) were prepared and tested for antithrombogenicity in vitro. The results indicate that the antithrombogenicity of the copolymers basically increases with the increasing of the DP of polyoxyethylene (POE) chain and tends to a plateau after the DP around 114,i.e.the long chain structure of POE is favourable to the antithrombogenicity of its copolymers;moreover,the extent of the improbement of antithrombogenicity also relates to the PEGMM content of the copolymers and the kind of the matrix that the POE chains are located on.These results are consistent with the anticipation of the hypothesis of maintaining proteins'normal conformations for blood compatible biomaterials.
Poly (ethyleneglycol monomethylether) methacrylate (PEGMM)was synthesized by means of the reaction of methacrylyl chloride with sodium monomethylpolyethyleneglycoxide and was characterized by FTIR, 1H-NMR,and ultraviolet spectrometries. A series of poly (vinyl alcohol)-graft-PEGMM (PVA-g-PEGMM )and methyl methacrylate-PEGMM copolymer (PMMA-PEGMM) were prepared and tested for antithrombogenicity in vitro. The results indicate that the antithrombogenicity of the copolymers basically increases with the increasing of the DP of polyoxyethylene (POE) chain and tends to a plateau after the DP around 114,i.e.the long chain structure of POE is favourable to the antithrombogenicity of its copolymers;moreover,the extent of the improbement of antithrombogenicity also relates to the PEGMM content of the copolymers and the kind of the matrix that the POE chains are located on.These results are consistent with the anticipation of the hypothesis of maintaining proteins'normal conformations for blood compatible biomaterials.
1992, 10(2): 127-136
Abstract:
A novel class of segmented copolymers, dimethyldiphenylpolysiloxane/poly (oxytetramethylene)-polyurea (PSPEU), was synthesized from α , ω-bis (γ-aminopropyl) dimethyldiphenylpolysiloxane (APMPS), which was prepared by means of basic ring-opening copolymerization of octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and 1, 3-bis (γ-aminopropyl) tetramethyl disiloxane. The relationships between the diphenylsiloxy contents and the properties of APMPS, including refractive index, glass transition temperature,solubility parameter as well as thermal stability,were investigated;meanwhile,the thermal stability,dynamic mechanical properties,mechanical properies as well as the antithrombogenicity in vitro of the PSPEU were also revealed.
A novel class of segmented copolymers, dimethyldiphenylpolysiloxane/poly (oxytetramethylene)-polyurea (PSPEU), was synthesized from α , ω-bis (γ-aminopropyl) dimethyldiphenylpolysiloxane (APMPS), which was prepared by means of basic ring-opening copolymerization of octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and 1, 3-bis (γ-aminopropyl) tetramethyl disiloxane. The relationships between the diphenylsiloxy contents and the properties of APMPS, including refractive index, glass transition temperature,solubility parameter as well as thermal stability,were investigated;meanwhile,the thermal stability,dynamic mechanical properties,mechanical properies as well as the antithrombogenicity in vitro of the PSPEU were also revealed.
1992, 10(2): 137-144
Abstract:
Ten fractionated samples of Chinese lacquer polysaccharide in aqueous 0.1M NaC1 solution were studied by aqueous-phase gel permeation chromatography (GPC). The universal calibration, broad MWD calibration and corrected column dispersion were adopted to the analysis of GPC chromatograms of the polysaccharide. The molecular weights Mw, Mn and polydispersity index Mw/Mn obtained from GPC are in good agreement with the results of light scattering and membrane osmometry. It is verified that the universal calibration concept is applicable to the lacquer polysaccharide having a number of side chains.
Ten fractionated samples of Chinese lacquer polysaccharide in aqueous 0.1M NaC1 solution were studied by aqueous-phase gel permeation chromatography (GPC). The universal calibration, broad MWD calibration and corrected column dispersion were adopted to the analysis of GPC chromatograms of the polysaccharide. The molecular weights Mw, Mn and polydispersity index Mw/Mn obtained from GPC are in good agreement with the results of light scattering and membrane osmometry. It is verified that the universal calibration concept is applicable to the lacquer polysaccharide having a number of side chains.
1992, 10(2): 145-151
Abstract:
The strain induced crystallization behaviour in polyimide from 1,4-bis (3', 4'- dicarboxyphenoxy)benzene and 4,4'-oxydianiline (PEI-E)has been investigated by WAXD, DSC and FTIR. The results obtained show that crystallization in PEI-E did take place just after tensile yielding. Meanwhile, the effect of strain induced crystallization on the thermomechanical properties was studied by DMA and TMA, the results of which indicate that the crystallization and hot stretching have a certain influence on the dynamic mechanical properties,such as weakening the β relaxation and decreasing the glass transition temperature.The TMA results confirm the shifting of glass transition temperature to lower temperature region after hot stretching.This phenomenon could be well explained by the effect of residual stress according to Eyring's theory.
The strain induced crystallization behaviour in polyimide from 1,4-bis (3', 4'- dicarboxyphenoxy)benzene and 4,4'-oxydianiline (PEI-E)has been investigated by WAXD, DSC and FTIR. The results obtained show that crystallization in PEI-E did take place just after tensile yielding. Meanwhile, the effect of strain induced crystallization on the thermomechanical properties was studied by DMA and TMA, the results of which indicate that the crystallization and hot stretching have a certain influence on the dynamic mechanical properties,such as weakening the β relaxation and decreasing the glass transition temperature.The TMA results confirm the shifting of glass transition temperature to lower temperature region after hot stretching.This phenomenon could be well explained by the effect of residual stress according to Eyring's theory.
1992, 10(2): 152-157
Abstract:
The secondary electrons spectrum in XPS can be used to determine the work function of polyaniline (PANI). It is shown that the work function of PANI depends on the protonation state and the polymerization method used.
The secondary electrons spectrum in XPS can be used to determine the work function of polyaniline (PANI). It is shown that the work function of PANI depends on the protonation state and the polymerization method used.
1992, 10(2): 158-163
Abstract:
The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing micioscope were observed for solution cast specimens, They were composed of radially growing crystalline lamellae of thickness around 100. It was found that the molecules were packed in the thickness direction. Banded texture was observed in randomly packed domains for melt cast specimens. The bands have the same width and internal structure as those usually observed in oriented specimens of these polymers obtained by shearing their mesomorphic melt.
The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing micioscope were observed for solution cast specimens, They were composed of radially growing crystalline lamellae of thickness around 100. It was found that the molecules were packed in the thickness direction. Banded texture was observed in randomly packed domains for melt cast specimens. The bands have the same width and internal structure as those usually observed in oriented specimens of these polymers obtained by shearing their mesomorphic melt.
1992, 10(2): 164-168
Abstract:
Polymerization of acrylamide initiated by ceric ammonium nitrate alone has been studied in aqueous medium. The effects of UV light irradiation on the initial rates of polymerization, the activation energy and on the polymer molecular weights have been investigated. Compared with that in the dark, the rate of polymerization under UV light was accelerated to eleven times higher, and the overall activation energy was lowered markedly.
Polymerization of acrylamide initiated by ceric ammonium nitrate alone has been studied in aqueous medium. The effects of UV light irradiation on the initial rates of polymerization, the activation energy and on the polymer molecular weights have been investigated. Compared with that in the dark, the rate of polymerization under UV light was accelerated to eleven times higher, and the overall activation energy was lowered markedly.
1992, 10(2): 169-175
Abstract:
The influences of UV light irradiation (313 nm) and diffused daylight on the polymerization of methyl acrylate initiated by the ceric ammonium nitrate without any reducing agent have been studied both in aqueous nitric acid and in pure water. The rate of polymerization was found to be accelerated and the overall activation energy and the induction time were found to be decreased sharply by the UV light irradiation. Under UV light, the rate of polymerization is 8 times as high as the rate in dark. The rate of polymerization is 8 times as high as the rate in dark.The rate of polymerization was found to attain a maximum with the increase of nitric acid concentration and the rate of polymerization became less sensitive to UV light in the presence of nitric acid whereas the induction period reduced outstandingly.Based on the experimental results,the mechanism is proposed.
The influences of UV light irradiation (313 nm) and diffused daylight on the polymerization of methyl acrylate initiated by the ceric ammonium nitrate without any reducing agent have been studied both in aqueous nitric acid and in pure water. The rate of polymerization was found to be accelerated and the overall activation energy and the induction time were found to be decreased sharply by the UV light irradiation. Under UV light, the rate of polymerization is 8 times as high as the rate in dark. The rate of polymerization is 8 times as high as the rate in dark.The rate of polymerization was found to attain a maximum with the increase of nitric acid concentration and the rate of polymerization became less sensitive to UV light in the presence of nitric acid whereas the induction period reduced outstandingly.Based on the experimental results,the mechanism is proposed.
COMPATIBILITY IN POLYMER BLENDS OF POLY (VINYL ACETATE) AND POLY (METHYL METHACRYLATE)STUDIED BY NMR
1992, 10(2): 176-179
Abstract:
Compatibility of poly (vinyl acetate) (PVAc) with poly (methyl methacrylate) (PMMA) mixtures has been studied by using nuclear magnetic relaxation, differential scanning calorimeter and small-angle X-ray scattering techniques. The nuclear magnetic relaxation time T1's were measured as a function of composition in blends of PMMA and PVAc prepared from chloroform solution. The results show that the system is miscible for casting from chloroform solution.
Compatibility of poly (vinyl acetate) (PVAc) with poly (methyl methacrylate) (PMMA) mixtures has been studied by using nuclear magnetic relaxation, differential scanning calorimeter and small-angle X-ray scattering techniques. The nuclear magnetic relaxation time T1's were measured as a function of composition in blends of PMMA and PVAc prepared from chloroform solution. The results show that the system is miscible for casting from chloroform solution.
1992, 10(2): 180-186
Abstract:
An Abbe refractometer with a rotatable polarizer mounted on the eyepiece is used for determining the two principal refractive indices of methyl-cyanoethyl cellulose/dichloroacetic acid liquid crystalline solutions. The critical concentration where the mesophase appears can be determined according to the variation of the increment of the refractive index with the concentration. Mesophase textures of the liquid crystalline solutions are observed and the influence of the concentration on mesophase textures is also discussed.
An Abbe refractometer with a rotatable polarizer mounted on the eyepiece is used for determining the two principal refractive indices of methyl-cyanoethyl cellulose/dichloroacetic acid liquid crystalline solutions. The critical concentration where the mesophase appears can be determined according to the variation of the increment of the refractive index with the concentration. Mesophase textures of the liquid crystalline solutions are observed and the influence of the concentration on mesophase textures is also discussed.
1992, 10(2): 187-194
Abstract:
A group of the mesogen jacketed liquid crystal polymers based on the monomers 2,5-bis (4-substituted benzoyl)oxystyrenes are synthesized. The substituents include alkoxy, alkyl, and cyano groups. The synthesis and the primary characterization of the liquid crystal phase of the monomers and the polymers are described. While some of the monomers give smectic textures the polymers are found to be nematic above their melting or glass transition temperatures. Interestingly the unsubstituted monomer and its polymer poly 2,5-di(benzoyloxy) styrene are also liquid crystalline.The single crystal structure of one of the monomers is also discussed.
A group of the mesogen jacketed liquid crystal polymers based on the monomers 2,5-bis (4-substituted benzoyl)oxystyrenes are synthesized. The substituents include alkoxy, alkyl, and cyano groups. The synthesis and the primary characterization of the liquid crystal phase of the monomers and the polymers are described. While some of the monomers give smectic textures the polymers are found to be nematic above their melting or glass transition temperatures. Interestingly the unsubstituted monomer and its polymer poly 2,5-di(benzoyloxy) styrene are also liquid crystalline.The single crystal structure of one of the monomers is also discussed.
