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1986 Volume 4 Issue 2
1986, 4(2): 109-118
Abstract:
1986, 4(2): 119-125
Abstract:
The molecular weight separation and column dispersion for a number of SEC columns packedwith various packing materials were calibrated simultaneously using narrow MWD polystyrene stan-dards as probe. The molecular weight dependence of the spreading factor is closely related to thesurface structure in the pore of packings.
The molecular weight separation and column dispersion for a number of SEC columns packedwith various packing materials were calibrated simultaneously using narrow MWD polystyrene stan-dards as probe. The molecular weight dependence of the spreading factor is closely related to thesurface structure in the pore of packings.
1986, 4(2): 126-133
Abstract:
The long chain branching of polybutadienes (PB) was measured with gel permeation chroma-tography coupled to an automatically recording capillary viscometer. In this method the experimentalrelation [η] (V) was translated into the calibration curve [η] (VR) for the monodisperse species. The curve is combined with the universal calibration so that the molecular weight distributionand an additional parameter, e.g. the average branching factor of this samples may be obtained. Longchain branching molecular weight changes with polymerization conditions.
The long chain branching of polybutadienes (PB) was measured with gel permeation chroma-tography coupled to an automatically recording capillary viscometer. In this method the experimentalrelation [η] (V) was translated into the calibration curve [η] (VR) for the monodisperse species. The curve is combined with the universal calibration so that the molecular weight distributionand an additional parameter, e.g. the average branching factor of this samples may be obtained. Longchain branching molecular weight changes with polymerization conditions.
1986, 4(2): 134-141
Abstract:
The states of water in poly (N-vinylpyrrolidone-methylmethacrylate) and poly (N-vinylpyrroli-done-2-hydroxyethyl methacrylate) hydrogels have been studied by means of DSC. The effect ofpolmer structure on equilibrium swelling extent of water has been examined. It was found that thestate of water and the water content in different hydrogels were dependent on the kind of monomer used,the component of copolymer, the sequence distribution of the monomer unit and the degree of cross-linking (including chemical and physical)to a great extent.The equilibrium water content of the hydrogel may be regarded as the sum of the different state of swollen water contents of the hydrogel.Based on these,a semiempirical formula used to estimate the equilibrium water content of the copolymer hydrogels was presented.
The states of water in poly (N-vinylpyrrolidone-methylmethacrylate) and poly (N-vinylpyrroli-done-2-hydroxyethyl methacrylate) hydrogels have been studied by means of DSC. The effect ofpolmer structure on equilibrium swelling extent of water has been examined. It was found that thestate of water and the water content in different hydrogels were dependent on the kind of monomer used,the component of copolymer, the sequence distribution of the monomer unit and the degree of cross-linking (including chemical and physical)to a great extent.The equilibrium water content of the hydrogel may be regarded as the sum of the different state of swollen water contents of the hydrogel.Based on these,a semiempirical formula used to estimate the equilibrium water content of the copolymer hydrogels was presented.
1986, 4(2): 142-147
Abstract:
A new method is proposed for estimation of weight-average molecular weight from the intrinsicviscosity and GPC chromatogram of a polymer sample for which Mark-Houwink coefficients are notknown. The method bases on an approximate relationship between GPC data and the intrinsicviscosity of the sample. Reliability of this method was tested by comparing with the universalcalibration method which requires known Mark-Houwink coefficients for seven samples havingdifferent molecular weight distributions. Results obtained by the new method are in excellent agree ment with those by the universal calibration method.
A new method is proposed for estimation of weight-average molecular weight from the intrinsicviscosity and GPC chromatogram of a polymer sample for which Mark-Houwink coefficients are notknown. The method bases on an approximate relationship between GPC data and the intrinsicviscosity of the sample. Reliability of this method was tested by comparing with the universalcalibration method which requires known Mark-Houwink coefficients for seven samples havingdifferent molecular weight distributions. Results obtained by the new method are in excellent agree ment with those by the universal calibration method.
1986, 4(2): 148-156
Abstract:
Four new organosilicon monomers containing nucleic acid bases or 5-fluorouracil (5-Fu) weresynthesized by the alkylation of γ-bromopropylmethyldiethoxysilane with uracil, thymine, adenineand 5-Fu, respectively. Polymerization of the monomers resulted in the formation of six new poly-siloxanes with nucleic acid bases as the pendant groups.
Four new organosilicon monomers containing nucleic acid bases or 5-fluorouracil (5-Fu) weresynthesized by the alkylation of γ-bromopropylmethyldiethoxysilane with uracil, thymine, adenineand 5-Fu, respectively. Polymerization of the monomers resulted in the formation of six new poly-siloxanes with nucleic acid bases as the pendant groups.
1986, 4(2): 157-164
Abstract:
The change of the pore structure of styrene-divinylbenzene copolymer caused by the presenceof the functional group has been discribed in this paper. The result indicates that the average poreredius, pore volume and surface area were reduced after the introduction of the functional groups.However, the surfase area of the resin containing--NH2 or --NHCH3 group and treated with waterand isopropyl alcohol was inareased prominently in comparison with that of the matrix copolymer. When the strongly polar ion exchange resin absorbs water,its pore diameter increases sharply.But the pore diameter of the weakly polar ion exchange resin does not change very much when it absorbs water gradually.
The change of the pore structure of styrene-divinylbenzene copolymer caused by the presenceof the functional group has been discribed in this paper. The result indicates that the average poreredius, pore volume and surface area were reduced after the introduction of the functional groups.However, the surfase area of the resin containing--NH2 or --NHCH3 group and treated with waterand isopropyl alcohol was inareased prominently in comparison with that of the matrix copolymer. When the strongly polar ion exchange resin absorbs water,its pore diameter increases sharply.But the pore diameter of the weakly polar ion exchange resin does not change very much when it absorbs water gradually.
1986, 4(2): 165-169
Abstract:
Six polyamides with pendant 5-fluorouracil group were synthesized by the polycondensation ofdi-p-nitrophenyl N-(5-fluorouracil-1-acetyl)glutamate with a series of polymethylene diamines.All of the new polyamides obtained are soluble in water. Their chemical structures were confirmedby ~1H NMR, UV and IR spectra as well as elemental analyses. The antitumor activity of some ofthese polyamides were tested against Ehrlich Ascites Carcinoma in mice, IIIa showed an inhibitionrate of 43%.
Six polyamides with pendant 5-fluorouracil group were synthesized by the polycondensation ofdi-p-nitrophenyl N-(5-fluorouracil-1-acetyl)glutamate with a series of polymethylene diamines.All of the new polyamides obtained are soluble in water. Their chemical structures were confirmedby ~1H NMR, UV and IR spectra as well as elemental analyses. The antitumor activity of some ofthese polyamides were tested against Ehrlich Ascites Carcinoma in mice, IIIa showed an inhibitionrate of 43%.
1986, 4(2): 170-179
Abstract:
In the X-ray diffiaction intensity distribution diagram of PTFE, three diffraction peaks exist inthe range of Bragg angle 30--45°, which are very sensitive to the Crystal trausition at room temperature.At 15℃, the crystal is triclinic and the "small spikes" along with the main peaks appear on the dif-fraction scans due to the distortion of the unit cell, while at 23℃, distortion no longer exists, "smallspikes" disappear completely. When the temperature is raised to 34℃, the hexagonal crystal fur-ther randomizes and the peak at Bragg angle 42°vanishes.We assigned correctly Miller index(108)to this peak and used 2θ=30-45℃ region("sensitive region") as a criterion to characterize qualitatively the crystal transition.It has been found that some factors such as γ-irradiation,cold pressing,drawing,calendering and copolymerization which are usually encountered in the fabrication or application of PTFE articles have profound effect on the crystal transition as evidenced by X-ray diffraction patterns and DSC thermograms.The information obtained in the present work is beneficial to the use of PTFE articles.
In the X-ray diffiaction intensity distribution diagram of PTFE, three diffraction peaks exist inthe range of Bragg angle 30--45°, which are very sensitive to the Crystal trausition at room temperature.At 15℃, the crystal is triclinic and the "small spikes" along with the main peaks appear on the dif-fraction scans due to the distortion of the unit cell, while at 23℃, distortion no longer exists, "smallspikes" disappear completely. When the temperature is raised to 34℃, the hexagonal crystal fur-ther randomizes and the peak at Bragg angle 42°vanishes.We assigned correctly Miller index(108)to this peak and used 2θ=30-45℃ region("sensitive region") as a criterion to characterize qualitatively the crystal transition.It has been found that some factors such as γ-irradiation,cold pressing,drawing,calendering and copolymerization which are usually encountered in the fabrication or application of PTFE articles have profound effect on the crystal transition as evidenced by X-ray diffraction patterns and DSC thermograms.The information obtained in the present work is beneficial to the use of PTFE articles.
1986, 4(2): 180-189
Abstract:
Some water-soluble bipolymer-Pd complexes were prepared. It was found that the bipolymer-Pd complexes exhibited remarkably higher catalytic activity and stability than that of the single polymer-Pd complex for hydrogenation of nitro-compounds and olefins under mild conditions.
Some water-soluble bipolymer-Pd complexes were prepared. It was found that the bipolymer-Pd complexes exhibited remarkably higher catalytic activity and stability than that of the single polymer-Pd complex for hydrogenation of nitro-compounds and olefins under mild conditions.
1986, 4(2): 190-193
Abstract:
A new photostabilizer--2,2,6,6-tetramethyl-4-piperidinylsalicylate (TMPS) has been syn-thesized by ester-exchange reaction between 2,2, 6, 6-tetramethyl-4-piperidinol and methylsalicylate.The photostabilizing effect of TMPS and Tinuvin 770, PDS on the photodegradation of cis-1,4-polybutadiene has been investigated for comparison. The results observed show that the mosteffective stabilizer of the three is TMPS. The reason of the good photostabilizing effect of TMPSwas discussed by fluorescence spectra.
A new photostabilizer--2,2,6,6-tetramethyl-4-piperidinylsalicylate (TMPS) has been syn-thesized by ester-exchange reaction between 2,2, 6, 6-tetramethyl-4-piperidinol and methylsalicylate.The photostabilizing effect of TMPS and Tinuvin 770, PDS on the photodegradation of cis-1,4-polybutadiene has been investigated for comparison. The results observed show that the mosteffective stabilizer of the three is TMPS. The reason of the good photostabilizing effect of TMPSwas discussed by fluorescence spectra.
1986, 4(2): 194-199
Abstract:
The catalytic effect of Mo Cln (OR)4-n-(i-Bu)2AlOPh on the polymerization of butadiene inhydrogenated gasoline is studied (R is alkyl, cycloheptyl, phenyl of C4-16). In this system, the solu-bility and the catalytic activity of the catalyst do not depend on whether the number of carbon atomsin R group is odd or even. The R group with the primary and secondary carbon atom has a fairlygreat influence on the catalytic activity. When R is an alkyl, the catalytic activity increases and therange of Al/Mo values that keeps higher conversion of butadiene is broadened as the size of the R group increases.The content of 1,2-units in the polymer hardly varies with the size of the R group.
The catalytic effect of Mo Cln (OR)4-n-(i-Bu)2AlOPh on the polymerization of butadiene inhydrogenated gasoline is studied (R is alkyl, cycloheptyl, phenyl of C4-16). In this system, the solu-bility and the catalytic activity of the catalyst do not depend on whether the number of carbon atomsin R group is odd or even. The R group with the primary and secondary carbon atom has a fairlygreat influence on the catalytic activity. When R is an alkyl, the catalytic activity increases and therange of Al/Mo values that keeps higher conversion of butadiene is broadened as the size of the R group increases.The content of 1,2-units in the polymer hardly varies with the size of the R group.
1986, 4(2): 200-206
Abstract:
In this paper the catalytic behaviour of tetravalent molybdenum catalyst system in polymeriza-tion of butadiene is dealt with. The effects of the variety of apions combined with molybdenumatom, the pattern of the substituent R in (i-Bu)2AlOR and the polymerization conditions on thebutadiene conversion, the molecular weight and its distribution and the microstructure of the polymeralso are studied. It has been found that the catalyst system is significantly active when anions com-bined with the molybdenum atom are acetoxy(CH3COO-) or ethoxy (C2H5O-).Obviously,the variety of substituent R in (i-Bu)2 AlOR has a great influence on the catalytic activity.The catalyst system is inactive if the R group is-COR'(R'is alkyl or aromatic group) or alkyl,whereas the activity of the catalyst system increases if the R group is phenyl or tolyl.With the rise of polymerization temperature the polymer molecular weight decreases,the distribution index of molecular weight increases and the content of 1,2-unit in polybutadiene reduces.
In this paper the catalytic behaviour of tetravalent molybdenum catalyst system in polymeriza-tion of butadiene is dealt with. The effects of the variety of apions combined with molybdenumatom, the pattern of the substituent R in (i-Bu)2AlOR and the polymerization conditions on thebutadiene conversion, the molecular weight and its distribution and the microstructure of the polymeralso are studied. It has been found that the catalyst system is significantly active when anions com-bined with the molybdenum atom are acetoxy(CH3COO-) or ethoxy (C2H5O-).Obviously,the variety of substituent R in (i-Bu)2 AlOR has a great influence on the catalytic activity.The catalyst system is inactive if the R group is-COR'(R'is alkyl or aromatic group) or alkyl,whereas the activity of the catalyst system increases if the R group is phenyl or tolyl.With the rise of polymerization temperature the polymer molecular weight decreases,the distribution index of molecular weight increases and the content of 1,2-unit in polybutadiene reduces.
