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1998 Volume 15 Issue 4
1998, 15(4): 1-4
Abstract:
The effect of methylaluminoxane(MAO) on butadiene polymerization catalyzed by polynuclear Nd-Al bimetallic complex has been examined. Compared with alkylaluminium MAO could improve the activity of the catalyst system to a higher extent even at n(Al)/n(Nd) 5~20 mol/mol. The chain transfer seems to be lower by using MAO than that by using alkylaluminium.
The effect of methylaluminoxane(MAO) on butadiene polymerization catalyzed by polynuclear Nd-Al bimetallic complex has been examined. Compared with alkylaluminium MAO could improve the activity of the catalyst system to a higher extent even at n(Al)/n(Nd) 5~20 mol/mol. The chain transfer seems to be lower by using MAO than that by using alkylaluminium.
1998, 15(4): 5-8
Abstract:
A series of water-soluble amphoteric cellulose derivatives were prepared by quaternary ammonium cationization of carboxymethylcellulose (CMC) in aqueous sodium hydroxide or potassium hydroxide by using 3-chloro-2-hydroxypropyltrime chloride (CHPAC) as the cationic monomer in isopropanol-water mixture. The quaternarization reaction was studied with respect to the drgree of substitution of quaternary ammonium (DSQ) of canonized CMC and the reaction efficiency of quaternarization variables studied included the content of carboxymethyl groups in CMC, the type and amount of alkali, the amount of CHPAC and the solvent composition. The IR, X-ray diffraction and DSC spectra of pure CMC and the quaternized CMC with different DSQ were investigated and their be-haviour in aqueous solution was studied by viscosity measurements.
A series of water-soluble amphoteric cellulose derivatives were prepared by quaternary ammonium cationization of carboxymethylcellulose (CMC) in aqueous sodium hydroxide or potassium hydroxide by using 3-chloro-2-hydroxypropyltrime chloride (CHPAC) as the cationic monomer in isopropanol-water mixture. The quaternarization reaction was studied with respect to the drgree of substitution of quaternary ammonium (DSQ) of canonized CMC and the reaction efficiency of quaternarization variables studied included the content of carboxymethyl groups in CMC, the type and amount of alkali, the amount of CHPAC and the solvent composition. The IR, X-ray diffraction and DSC spectra of pure CMC and the quaternized CMC with different DSQ were investigated and their be-haviour in aqueous solution was studied by viscosity measurements.
1998, 15(4): 9-12
Abstract:
A series of epoxide-containing acrylic polymer modifiers (HGMB) were synthesized. The dynamic mechanical behavior and impact strengths of the modified systems, epoxy resin E-51/4, 4'-diaminodiphenylmethane (DDM)/HGMB, were investigated. The results showed that both the structure and amount of the modifiers affected the impact strength and modulus of the modified systems significantly. The addition of 15%(mass fraction) HGMB (4.3% glycidyl methacrylate (GMA), 5 % hydroxyethyl methacrylate(HEMA), 25.7% methyl methacrylate (MMA) and 65 % butyl acrylate (BA) (mole fraction)) resulted in a 50% increase in impact strength and an obvious increase in Tg of the modified system but only little loss of its modulus.
A series of epoxide-containing acrylic polymer modifiers (HGMB) were synthesized. The dynamic mechanical behavior and impact strengths of the modified systems, epoxy resin E-51/4, 4'-diaminodiphenylmethane (DDM)/HGMB, were investigated. The results showed that both the structure and amount of the modifiers affected the impact strength and modulus of the modified systems significantly. The addition of 15%(mass fraction) HGMB (4.3% glycidyl methacrylate (GMA), 5 % hydroxyethyl methacrylate(HEMA), 25.7% methyl methacrylate (MMA) and 65 % butyl acrylate (BA) (mole fraction)) resulted in a 50% increase in impact strength and an obvious increase in Tg of the modified system but only little loss of its modulus.
1998, 15(4): 13-16
Abstract:
Cobalt hexacyanoferrate (CoHCF) microcrystallites exhibited well-defined cyclic voltammetric waves in polyethylene glycol. The peak current of COHCF was linear to the scanning speed at 100 mV/s and lower. In-situ IR spectra indicated that the redox involved interchange of ferric and ferrous states of the hexacyanoferrate. CoHCF catalyzed the oxidation of ascorbic acid with the oxidation peak poteneial shifting negatively to 183 mV. A catalysis mechanism is proposed.
Cobalt hexacyanoferrate (CoHCF) microcrystallites exhibited well-defined cyclic voltammetric waves in polyethylene glycol. The peak current of COHCF was linear to the scanning speed at 100 mV/s and lower. In-situ IR spectra indicated that the redox involved interchange of ferric and ferrous states of the hexacyanoferrate. CoHCF catalyzed the oxidation of ascorbic acid with the oxidation peak poteneial shifting negatively to 183 mV. A catalysis mechanism is proposed.
1998, 15(4): 17-20
Abstract:
The CeO2-TiO2 composite nanocrystalline porous film electrodes prepared by solgel method have been investigated by XRD, AFM and photoelectrochemcal methods. The transpositions of p- and n-type photoresponses were observed on the composite film electrodes for the first time. It could be due to the competition between CeO2 and TiO2 photoresponses. This result Aught have a potential application in smart window and solar energy conversion.
The CeO2-TiO2 composite nanocrystalline porous film electrodes prepared by solgel method have been investigated by XRD, AFM and photoelectrochemcal methods. The transpositions of p- and n-type photoresponses were observed on the composite film electrodes for the first time. It could be due to the competition between CeO2 and TiO2 photoresponses. This result Aught have a potential application in smart window and solar energy conversion.
1998, 15(4): 21-24
Abstract:
Polyacrylonitrile coating was formed on aluminium cathode by in-situ electrochem-ical polymerization(ECP) at constant potential. The influences of supporting electrolytes, cell potential and monomer concentration on the performance and morphology of the coatings have been studied. The coatings in 10~15 pm thickness could be obtained at polymerization potential of 7.0 V for 3 h in 1~5 mol/L AN solution of aqueous DMF containing 0.05 mol/L AlCl3 as supporting electrolyte. The morphology and structure of the coatings have been examined by SEM and FTIR. The mechanism of ECP has been discussed briefly.
Polyacrylonitrile coating was formed on aluminium cathode by in-situ electrochem-ical polymerization(ECP) at constant potential. The influences of supporting electrolytes, cell potential and monomer concentration on the performance and morphology of the coatings have been studied. The coatings in 10~15 pm thickness could be obtained at polymerization potential of 7.0 V for 3 h in 1~5 mol/L AN solution of aqueous DMF containing 0.05 mol/L AlCl3 as supporting electrolyte. The morphology and structure of the coatings have been examined by SEM and FTIR. The mechanism of ECP has been discussed briefly.
1998, 15(4): 25-28
Abstract:
NO2- ions can be remarkably reduced by reaction in the presence of TiO2 as catalyst under UV light irradiation. The kinetic study shows that it is a multistepwise complex reaction and the rate-determining step is the oxidation of NO2- ions on the surface of TiO2. The reaction follows Langmuir-Hiushelwood mechamsm. Oxygen promotes the reaction.
NO2- ions can be remarkably reduced by reaction in the presence of TiO2 as catalyst under UV light irradiation. The kinetic study shows that it is a multistepwise complex reaction and the rate-determining step is the oxidation of NO2- ions on the surface of TiO2. The reaction follows Langmuir-Hiushelwood mechamsm. Oxygen promotes the reaction.
1998, 15(4): 29-32
Abstract:
The extraction of nitric acid and U(Ⅵ) from nitric acid solutions with N, N, N', N'-tetrahexylmalonamide (THMA) in toluene has been carried out. The dependences of the extraction distribution ratios on the concentrations of aqueous nitric acid, extractant and sodium nitrate and the temperature have been investigated. The extraction stoichiometry has been established and the structure of the extracted complex was analyzed by IR spectrometry. The extraction constants of nitric acid and U(Ⅳ) with THMA and the reaction enthalpy were calculated. In comparison with the extractability of N, N, N', N'-tetrabutylmalonamide, it shows that increase in the alkyl chain longth lowering the formation of the third phase and decreases the extractability of the amides.
The extraction of nitric acid and U(Ⅵ) from nitric acid solutions with N, N, N', N'-tetrahexylmalonamide (THMA) in toluene has been carried out. The dependences of the extraction distribution ratios on the concentrations of aqueous nitric acid, extractant and sodium nitrate and the temperature have been investigated. The extraction stoichiometry has been established and the structure of the extracted complex was analyzed by IR spectrometry. The extraction constants of nitric acid and U(Ⅳ) with THMA and the reaction enthalpy were calculated. In comparison with the extractability of N, N, N', N'-tetrabutylmalonamide, it shows that increase in the alkyl chain longth lowering the formation of the third phase and decreases the extractability of the amides.
1998, 15(4): 33-36
Abstract:
Samples of nylon-11 annealling at various temperatures were prepared. Their crystallinity and structures were investigated by WAXD, DSC and density measurements. The thermodynamical parameters of samples were calculated and the formula of drgree of crystallinity was derived.
Samples of nylon-11 annealling at various temperatures were prepared. Their crystallinity and structures were investigated by WAXD, DSC and density measurements. The thermodynamical parameters of samples were calculated and the formula of drgree of crystallinity was derived.
1998, 15(4): 37-40
Abstract:
A series of ceria-lanthanide oxide CeO2-LnO1.5 (Ln=La, Nd, Sm, Gd) solu solutions were prepared in n(Ce): n(Ln) ratio of 1:1 by coprecipitation method. Their partly distorted fluorite structures were revealed by specific surface, XRD, Raman spectrum and TEM results. The structure change of the solid solution due to the entering of Ln3+ ions into CeO2 lattice could make both the surface and bulk of the solid solution participate in the redox reaction simultaneously. The solid solutions were found to be highly active for catalytic combustion of methane.
A series of ceria-lanthanide oxide CeO2-LnO1.5 (Ln=La, Nd, Sm, Gd) solu solutions were prepared in n(Ce): n(Ln) ratio of 1:1 by coprecipitation method. Their partly distorted fluorite structures were revealed by specific surface, XRD, Raman spectrum and TEM results. The structure change of the solid solution due to the entering of Ln3+ ions into CeO2 lattice could make both the surface and bulk of the solid solution participate in the redox reaction simultaneously. The solid solutions were found to be highly active for catalytic combustion of methane.
1998, 15(4): 41-44
Abstract:
Some vanadium-substituted hetropolytungstates were synthesized. Their toxicity to the cells of RK and activity to antipseudorabies virus at nontoxic concentrations were tested by cell-culture methods. The results showed that some of the compounds had high anti-PRV activity at nontoxic concentration. Among them three had high antivirus and selective activity with median effective concentration 3.2~5.0 mg/L and cell median toxicity concentration 400~420 mg/L. At concentration of the compounds 12.5 mg/L the inhibition to PRV was more than 70%~80%, while virus TCID50 values descended four log. The relation between the structure and activity has been discussed briefly.
Some vanadium-substituted hetropolytungstates were synthesized. Their toxicity to the cells of RK and activity to antipseudorabies virus at nontoxic concentrations were tested by cell-culture methods. The results showed that some of the compounds had high anti-PRV activity at nontoxic concentration. Among them three had high antivirus and selective activity with median effective concentration 3.2~5.0 mg/L and cell median toxicity concentration 400~420 mg/L. At concentration of the compounds 12.5 mg/L the inhibition to PRV was more than 70%~80%, while virus TCID50 values descended four log. The relation between the structure and activity has been discussed briefly.
1998, 15(4): 45-48
Abstract:
The film formation process of corrosion inhibitors on copper in neutral solutions was studied by combination of photoelectrochemical technique with electrochemical quartz crystal microbalance(PECQCM). It is found that the film growth on the copper in Na2SO4 solution with oxidizing inhibitor Na2CrO4 follows the parabola type line, while in NaCl solution it appears to be a broken line. The precipitation type inhibitor Na2SiO3 will form film on the copper electrode in NaCl solution, but not in Na2SO4 solution.
The film formation process of corrosion inhibitors on copper in neutral solutions was studied by combination of photoelectrochemical technique with electrochemical quartz crystal microbalance(PECQCM). It is found that the film growth on the copper in Na2SO4 solution with oxidizing inhibitor Na2CrO4 follows the parabola type line, while in NaCl solution it appears to be a broken line. The precipitation type inhibitor Na2SiO3 will form film on the copper electrode in NaCl solution, but not in Na2SO4 solution.
1998, 15(4): 49-53
Abstract:
The influence of the amount of ethylene-acrylic acid random copolymer(EAA) on morphology and mechanieal properties of linear low-desnity polyethylene (LLDPE)/styrene-acrylonitrile copolymer (SAN) blends compatibilized by EAA was studied by SEM and me-chanical properties measurements. The results show that the addition of a small amount of EAA leads to a decrease in domain size of the SAN phase and an increase in modulus, tensile strength and elongation at break. When the amount of EAA(c) is up to about 11.7% (mass fraction), the saturated concentration(Cs), that is, the point of inter facial saturation on the SAN phase, is reached. When c is much higher than Cs, the excess EAA acts mainly as a toughening agent of the LLDPE/SAN blends. The compatibilizing effect of EAA is due to partial compatibility of the amorphous phases of EAA and LLDPE, and the specific interaction between EAA and SAN.
The influence of the amount of ethylene-acrylic acid random copolymer(EAA) on morphology and mechanieal properties of linear low-desnity polyethylene (LLDPE)/styrene-acrylonitrile copolymer (SAN) blends compatibilized by EAA was studied by SEM and me-chanical properties measurements. The results show that the addition of a small amount of EAA leads to a decrease in domain size of the SAN phase and an increase in modulus, tensile strength and elongation at break. When the amount of EAA(c) is up to about 11.7% (mass fraction), the saturated concentration(Cs), that is, the point of inter facial saturation on the SAN phase, is reached. When c is much higher than Cs, the excess EAA acts mainly as a toughening agent of the LLDPE/SAN blends. The compatibilizing effect of EAA is due to partial compatibility of the amorphous phases of EAA and LLDPE, and the specific interaction between EAA and SAN.
1998, 15(4): 54-58
Abstract:
The melt reactive blending and dynamic mechanical properties of HIPS/PP blends in the presence of dicumyl peroxide(DCP) were studied. The results show that the degradation of PS was the main process in HIPS/DCP mixture while the cross-linking and grafting are the predominate in the PB phases. PP was degraded when it was mixed with DCP in molten state. However, the grafting of PP onto HIPS was a main process in HIPS/PP/DCP blends. The characteristic of molecular motion in HIPS/PP/DCP blends is significantly different from that in HIPS/PP blends. The glass transition temperature of PS phase was decreased and that of PB and PP phases were increased. The melt reaction mixing of HIPS/PP blends led to the in-situ compatibilization.
The melt reactive blending and dynamic mechanical properties of HIPS/PP blends in the presence of dicumyl peroxide(DCP) were studied. The results show that the degradation of PS was the main process in HIPS/DCP mixture while the cross-linking and grafting are the predominate in the PB phases. PP was degraded when it was mixed with DCP in molten state. However, the grafting of PP onto HIPS was a main process in HIPS/PP/DCP blends. The characteristic of molecular motion in HIPS/PP/DCP blends is significantly different from that in HIPS/PP blends. The glass transition temperature of PS phase was decreased and that of PB and PP phases were increased. The melt reaction mixing of HIPS/PP blends led to the in-situ compatibilization.
1998, 15(4): 59-61
Abstract:
The correlation between the catalytic activity and structure of Sn0.8Mo0.2 mixed oxides calcinated at diffrent temperatures has been investigated by using ESR, XPS and XRD techniques. The results show that at 100~300 ℃ molybdenum disperses on the surface of rutile-type stannic oxide formed at 100℃, at 300~500℃ it gradually diffuses into SnO2 and at 550℃ the interstitial solid solution forms, which exhibites the best catalytic activity in oxidation of butene. The substitution solid solution forms at 600℃.
The correlation between the catalytic activity and structure of Sn0.8Mo0.2 mixed oxides calcinated at diffrent temperatures has been investigated by using ESR, XPS and XRD techniques. The results show that at 100~300 ℃ molybdenum disperses on the surface of rutile-type stannic oxide formed at 100℃, at 300~500℃ it gradually diffuses into SnO2 and at 550℃ the interstitial solid solution forms, which exhibites the best catalytic activity in oxidation of butene. The substitution solid solution forms at 600℃.
1998, 15(4): 62-64
Abstract:
The reaction of methane with CO2 and H2O using catalyst MCD-2(α-Al2O3 with 15%~17% impregnated NiO) has been investigated. After a 500 h continuous run underconditions: n (CH4): n (CO2): n (H2O)=1:1.5:0.9, CH4 space velocity 1000 h -1, bed temperature 600~900℃ and 0.6 MPa, it is found that the porous structure, mechanical strength,content of active nickel,XRD patterns and content of deposited carbon on the catalyst did not change drastically and the activity of the catalyst kept steady with the CH4 conversion,CO content on the product gas and H2/CO ratio being ≥92%, ~40% and ~1, respectively.
The reaction of methane with CO2 and H2O using catalyst MCD-2(α-Al2O3 with 15%~17% impregnated NiO) has been investigated. After a 500 h continuous run underconditions: n (CH4): n (CO2): n (H2O)=1:1.5:0.9, CH4 space velocity 1000 h -1, bed temperature 600~900℃ and 0.6 MPa, it is found that the porous structure, mechanical strength,content of active nickel,XRD patterns and content of deposited carbon on the catalyst did not change drastically and the activity of the catalyst kept steady with the CH4 conversion,CO content on the product gas and H2/CO ratio being ≥92%, ~40% and ~1, respectively.
1998, 15(4): 65-67
Abstract:
Water-soluble chitosan complex with zinc was prepared from oligomeric chitosan after oxidative degradation of chitosan. The process of complex formation were followed by UV and IR spectra measurements.
Water-soluble chitosan complex with zinc was prepared from oligomeric chitosan after oxidative degradation of chitosan. The process of complex formation were followed by UV and IR spectra measurements.
1998, 15(4): 68-70
Abstract:
The characteristics of the CO gas sensor with partly Nafion solid electrolyte have been studied with the method of electrolysis at a fixed potential. It is found that the sensor has the advantages of rapid response, low background current and noise etc. in comparison with that of the sensor using aqueous electrolyte. Hence, it may also be used for the measurement of low concentration CO gas.
The characteristics of the CO gas sensor with partly Nafion solid electrolyte have been studied with the method of electrolysis at a fixed potential. It is found that the sensor has the advantages of rapid response, low background current and noise etc. in comparison with that of the sensor using aqueous electrolyte. Hence, it may also be used for the measurement of low concentration CO gas.
1998, 15(4): 71-73
Abstract:
Di (2-ethylhexyl)phosphate levextrel resin(CL-P204) showed a maximum distribution coefficient for In(Ⅲ) adsorption at pH=1.0 in sulfuric acid. The steady adsorption capacity was 48.5 mg/g and the adsorption enthalpy was 9.2 kJ/mol. The isothermal adsorption equation is Q=60.2 c0.1 (25℃). The adsorption mechanism has been investigated by IR measurement.
Di (2-ethylhexyl)phosphate levextrel resin(CL-P204) showed a maximum distribution coefficient for In(Ⅲ) adsorption at pH=1.0 in sulfuric acid. The steady adsorption capacity was 48.5 mg/g and the adsorption enthalpy was 9.2 kJ/mol. The isothermal adsorption equation is Q=60.2 c0.1 (25℃). The adsorption mechanism has been investigated by IR measurement.
1998, 15(4): 74-76
Abstract:
The biological effects of Ge compounds on the rat with diabete mellitus is reported. The effects of Ge-132 on the pancreatic cells of young rat in vitro have been examined in order to elucidate the cytology mechanism. The results show that both 0.01 mmol/L and 1 mmol/L Ge-132 did not affect the morphology of the pancreatic cell. However, Ge-132 in concentration of 0.01 mmol/L revealed an obvious promotion of the pancreas of young rats to secrete insulin. The effect of Ge-132 was compared with that of GeO2.
The biological effects of Ge compounds on the rat with diabete mellitus is reported. The effects of Ge-132 on the pancreatic cells of young rat in vitro have been examined in order to elucidate the cytology mechanism. The results show that both 0.01 mmol/L and 1 mmol/L Ge-132 did not affect the morphology of the pancreatic cell. However, Ge-132 in concentration of 0.01 mmol/L revealed an obvious promotion of the pancreas of young rats to secrete insulin. The effect of Ge-132 was compared with that of GeO2.
1998, 15(4): 77-79
Abstract:
The epoxy resin E-51 has been modified with a new prepolymer containing spiroorthocarbonate. It is found that the addition of the prepolymer into epoxy resin system enhances the conversion of epoxy groups with the Tg and thermal stability of the matrix being slightly reduced. The adhesive tensile and shear strengths of the modified resin increased obviousely with the increase in prepolymer content. The relationship between the shrinkage and adhesive strengths of the products also has been investigated.
The epoxy resin E-51 has been modified with a new prepolymer containing spiroorthocarbonate. It is found that the addition of the prepolymer into epoxy resin system enhances the conversion of epoxy groups with the Tg and thermal stability of the matrix being slightly reduced. The adhesive tensile and shear strengths of the modified resin increased obviousely with the increase in prepolymer content. The relationship between the shrinkage and adhesive strengths of the products also has been investigated.
1998, 15(4): 80-82
Abstract:
The phase structure of La2O3-NiO system at various calcination temperatures have been studied by XRD and DTA-TG techniques. It is found that at 450-600℃ there are mixed phases of La2O3 and NiO and at 800~900℃ only a single phase of perovskite LaNiO3. The conductivity of the system increases with the increase in calcination temperature. At temperature 600~800℃ a sudden change of the conductivity occurred in correspondence with the phase transformation of the system. The catalytic activities of the system calcinated at 600℃ and 800℃ also show a distinct "activity gap" for CO methanation and xylene combustion.
The phase structure of La2O3-NiO system at various calcination temperatures have been studied by XRD and DTA-TG techniques. It is found that at 450-600℃ there are mixed phases of La2O3 and NiO and at 800~900℃ only a single phase of perovskite LaNiO3. The conductivity of the system increases with the increase in calcination temperature. At temperature 600~800℃ a sudden change of the conductivity occurred in correspondence with the phase transformation of the system. The catalytic activities of the system calcinated at 600℃ and 800℃ also show a distinct "activity gap" for CO methanation and xylene combustion.
1998, 15(4): 83-85
Abstract:
The optical basicities of some oxides have been calculated on the basis of Sanderson's partial charge. The results seem rather reasonable. The method also applies to the oxides of subgroup elements.
The optical basicities of some oxides have been calculated on the basis of Sanderson's partial charge. The results seem rather reasonable. The method also applies to the oxides of subgroup elements.
1998, 15(4): 86-88
Abstract:
Graft copolymerization of methylmethacrylate on chlorinated polyethylene was carried out in suspension by initiation with benzoyl peroxide. The reaction conditions and chlorine content of CPE in relation to the graft efficiency, graft degree and conversion rate were studied. The structures of the graft copolymers were characterized by IR and 1H NMR.
Graft copolymerization of methylmethacrylate on chlorinated polyethylene was carried out in suspension by initiation with benzoyl peroxide. The reaction conditions and chlorine content of CPE in relation to the graft efficiency, graft degree and conversion rate were studied. The structures of the graft copolymers were characterized by IR and 1H NMR.
1998, 15(4): 89-91
Abstract:
The title ligand(A) was synthesized through condensation of 2-pyridine aldehyde and L-methyl cysteine hydrochloride. The isomers of (A) were separated by column chromatography. The in-situ prepared catalyst from (A) with [Rh(COD)CI]2 (COD:cyclooctadiene) has been used to catalyze the asymmetric hydrosilylation of acetophenone. The results showed that only the configuration of C4, but not that of C2 affected the optical yield and configuration of the products.
The title ligand(A) was synthesized through condensation of 2-pyridine aldehyde and L-methyl cysteine hydrochloride. The isomers of (A) were separated by column chromatography. The in-situ prepared catalyst from (A) with [Rh(COD)CI]2 (COD:cyclooctadiene) has been used to catalyze the asymmetric hydrosilylation of acetophenone. The results showed that only the configuration of C4, but not that of C2 affected the optical yield and configuration of the products.
1998, 15(4): 92-94
Abstract:
The particulate hydrous oxides of rare-earth RExOy · nH2O(RE=Ce,Nd,La,Pr) have been prepared using polyacrylonitrile as adhesive agent. They showed better fluoride removing property. The adsorption mechanism in relation with the pH value and temperature of the solution have been discussed briefly.
The particulate hydrous oxides of rare-earth RExOy · nH2O(RE=Ce,Nd,La,Pr) have been prepared using polyacrylonitrile as adhesive agent. They showed better fluoride removing property. The adsorption mechanism in relation with the pH value and temperature of the solution have been discussed briefly.
1998, 15(4): 95-97
Abstract:
The reaction mechanism, reactivities, and apparent activation energies of epoxy/dicyanamide curing system accelerated by C6H5NHCONR2 (R=CH3, n-C4H9, i-C3H7) were studied by DSC and GC techniques. The results showed that in reaction of C6H5,NHCONR2 with either dicyanamide or epoxy resin there was a dimethylamine released reacting with epoxy resin, giving a tertiary amine, which accelerated the anionic homopolymerization of epoxy resin.
The reaction mechanism, reactivities, and apparent activation energies of epoxy/dicyanamide curing system accelerated by C6H5NHCONR2 (R=CH3, n-C4H9, i-C3H7) were studied by DSC and GC techniques. The results showed that in reaction of C6H5,NHCONR2 with either dicyanamide or epoxy resin there was a dimethylamine released reacting with epoxy resin, giving a tertiary amine, which accelerated the anionic homopolymerization of epoxy resin.
1998, 15(4): 98-100
Abstract:
The Ruettimnann's method[5] for vitamin K1 synthesis has been improved by using phase transfer catalyst in Diels-Alder condensation and using mixed trans-cis phytyl chloride instead of natural phytol as starting material in the synthesis. The vitamin K1 then obtained by a retro-Diels-Alder reaction has a cis-trans isomer ratio of 20.35 to 79.65 which meets the Chinese pharmacopia standard. Phytyl bromide in this case gave vitamin K1 with cis-trans ratio of 26.30 to 73.70.
The Ruettimnann's method[5] for vitamin K1 synthesis has been improved by using phase transfer catalyst in Diels-Alder condensation and using mixed trans-cis phytyl chloride instead of natural phytol as starting material in the synthesis. The vitamin K1 then obtained by a retro-Diels-Alder reaction has a cis-trans isomer ratio of 20.35 to 79.65 which meets the Chinese pharmacopia standard. Phytyl bromide in this case gave vitamin K1 with cis-trans ratio of 26.30 to 73.70.
1998, 15(4): 101-103
Abstract:
The graft copolymerization of starch and methyl acrylate(MA) in three different reaction systems, MA-CH3OH-H2O, aqueous solution, emulsion system has been carried out. The composition of the grafted PMA in copolymer and homopolymer PMA, the viscosity-average molecular weight of the graft copolymer, the graft efficiency and freqency and the microstructure and mechanical property have been investigated. The biodegradable graft plastics with 60% starch was obtained.
The graft copolymerization of starch and methyl acrylate(MA) in three different reaction systems, MA-CH3OH-H2O, aqueous solution, emulsion system has been carried out. The composition of the grafted PMA in copolymer and homopolymer PMA, the viscosity-average molecular weight of the graft copolymer, the graft efficiency and freqency and the microstructure and mechanical property have been investigated. The biodegradable graft plastics with 60% starch was obtained.
1998, 15(4): 104-106
Abstract:
The partial deposit films on p-silicon wafers were formed from three kinds of plating solution:chloro-platinic acid, potassium tetranitroplatinate and diammine platinium dinitrate under Nd:YAG laser irradiation. The compositions and properties of the deposits were investigated by AES, SEM and XPS techniques. The Pt deposits have ohmic contact with p-type silicon.
The partial deposit films on p-silicon wafers were formed from three kinds of plating solution:chloro-platinic acid, potassium tetranitroplatinate and diammine platinium dinitrate under Nd:YAG laser irradiation. The compositions and properties of the deposits were investigated by AES, SEM and XPS techniques. The Pt deposits have ohmic contact with p-type silicon.
1998, 15(4): 107-108
Abstract:
Five fluorescent bromotriphenodioxazines were syntheslied. As fluorescent pig-ments and dyes their visible absorption and fluorescence spectra were determined and examined.
Five fluorescent bromotriphenodioxazines were syntheslied. As fluorescent pig-ments and dyes their visible absorption and fluorescence spectra were determined and examined.
1998, 15(4): 109-110
Abstract:
Tetraacryloxyethoxysilane syntheslied by the reaction of 2-hydroxyethyl acrylate with silicon tetrachloride was used in preparation of the transparent poly (2-hydroxyethylacrylate)/silicon dioxide composites by sol-gel method. The composition of the composites were analyzed by electronic energy spectroscopy, elemental analysis and thermogravimetry. The composites have transparency greater than 80%, with thermal stability being increased with the silicon dioxide content.
Tetraacryloxyethoxysilane syntheslied by the reaction of 2-hydroxyethyl acrylate with silicon tetrachloride was used in preparation of the transparent poly (2-hydroxyethylacrylate)/silicon dioxide composites by sol-gel method. The composition of the composites were analyzed by electronic energy spectroscopy, elemental analysis and thermogravimetry. The composites have transparency greater than 80%, with thermal stability being increased with the silicon dioxide content.
1998, 15(4): 111-112
Abstract:
Irradiation alkylation of diethyl malonate has been carried out with a high power stability program-control microwave "5 kW/2450 MHz" made in our laboratory. The microwave has advantages of accelerating synthesis, short reaction time, and reduced energy consumption.
Irradiation alkylation of diethyl malonate has been carried out with a high power stability program-control microwave "5 kW/2450 MHz" made in our laboratory. The microwave has advantages of accelerating synthesis, short reaction time, and reduced energy consumption.
1998, 15(4): 113-114
Abstract:
The catalytic activities of the supported PdO catalysts were found to be dependent on the kind of the support as follows: CeO2 >ZrO2 >TiO2 >Al2O3 >SnO2 >ZSM-5 >SiO2. The reduction state of PdO in the catalyst played an important role in the oxidation activity of the catalyst. PdO/CeO2 was inferior to PdO/Al2O3 in heat-stability, but its activity for CO oxidation was higher than PdO/Al2O3, after it had been calcinated at 1200 ℃ for 4 h.
The catalytic activities of the supported PdO catalysts were found to be dependent on the kind of the support as follows: CeO2 >ZrO2 >TiO2 >Al2O3 >SnO2 >ZSM-5 >SiO2. The reduction state of PdO in the catalyst played an important role in the oxidation activity of the catalyst. PdO/CeO2 was inferior to PdO/Al2O3 in heat-stability, but its activity for CO oxidation was higher than PdO/Al2O3, after it had been calcinated at 1200 ℃ for 4 h.
1998, 15(4): 115-116
Abstract:
The reactions of carbonyls with a low-valent titanium reagent prepared by TiCl4 with Mg in THF were carried out under ultrasonic action at room temperature for 10 min to 1 h and corresponding olefins were obtained in good yields. The results indicate that the tita-nium-induced reductive coupling of carbonyls to olefins is directly affected by ultra sonic due to the electron transfer process.
The reactions of carbonyls with a low-valent titanium reagent prepared by TiCl4 with Mg in THF were carried out under ultrasonic action at room temperature for 10 min to 1 h and corresponding olefins were obtained in good yields. The results indicate that the tita-nium-induced reductive coupling of carbonyls to olefins is directly affected by ultra sonic due to the electron transfer process.
