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1984 Volume 2 Issue 2
1984, 2(2): 109-116
Abstract:
Difference in thermal behavior of presumed polypropylene-b-polyethylene block copolymers(PP-PE) and corresponding PP+PE blends was studied. Different views in the literature were unified in our observation that faster cooling rate yielded only one exothermal peak for the blends, while slower cooling rates revealed both PP and PE exothermal peaks. Further details on when a single or double exothermal peaks would appear are discussed. Melting and crystallization temperatures for both PP and PE in blends were found to be a few degrees higher than for PP and PE in block copolymers.Thus,thermal analysis can be used to identify PP-PE block copolymers.These phenomena and the lower △Hf-values of PP and PE in block copolymers than the △Hf-values of pure homo-PP and-PE (for PE even more so)are explained in terms of restricted block movement due to covalent bond between blocks and of crystallization processes in block copolymers.The presence of block structure in the PP-PE samples studied is inferred.
Difference in thermal behavior of presumed polypropylene-b-polyethylene block copolymers(PP-PE) and corresponding PP+PE blends was studied. Different views in the literature were unified in our observation that faster cooling rate yielded only one exothermal peak for the blends, while slower cooling rates revealed both PP and PE exothermal peaks. Further details on when a single or double exothermal peaks would appear are discussed. Melting and crystallization temperatures for both PP and PE in blends were found to be a few degrees higher than for PP and PE in block copolymers.Thus,thermal analysis can be used to identify PP-PE block copolymers.These phenomena and the lower △Hf-values of PP and PE in block copolymers than the △Hf-values of pure homo-PP and-PE (for PE even more so)are explained in terms of restricted block movement due to covalent bond between blocks and of crystallization processes in block copolymers.The presence of block structure in the PP-PE samples studied is inferred.
1984, 2(2): 117-123
Abstract:
Two new polytriazines: poly[2-methyl-4, 6-(4,′ 4″-diphenylene)-1, 3, 5-triazine] (Ⅰ) and poly[2-phenyl-4, 6-(4′, 4″-diphenylene)-1, 3, 5-triazine] (Ⅱ) were synthesized from the solution condensation of biphenyl-4, 4′-diamidine dihydrochloride with acetic anhydride and biphenyl-4, 4′-diamidine with benzaldehyde respectively. These two polymers were characterized by TGA, DTA, elemental analysis and IR spectroscopy. They exhibited good thermal oxidative stability as shown by the fact that the powders of these polymers suffered 5.4%,2.4% weight loss after isothermal aging in air at 300℃ for 200 hours.The decomposition temperature of (Ⅱ) was 583℃ in air and 590℃ in N2.These linear poly-1,3,5-triazines were soluble in concentrated sulfuric acid,phosphoric acid and trifluoroacetic acid whereas the crosslinked poly-1,3,5-triazines reported in the literature were insoluble and infusible.It is interesting that these polymers can form complexes with metal halides as determined by X-ray photoelectron spectroscopy(XPS).The polymer metal complex(Ⅲ).PdCl2 possesses catalytic activity for hydrogenation.
Two new polytriazines: poly[2-methyl-4, 6-(4,′ 4″-diphenylene)-1, 3, 5-triazine] (Ⅰ) and poly[2-phenyl-4, 6-(4′, 4″-diphenylene)-1, 3, 5-triazine] (Ⅱ) were synthesized from the solution condensation of biphenyl-4, 4′-diamidine dihydrochloride with acetic anhydride and biphenyl-4, 4′-diamidine with benzaldehyde respectively. These two polymers were characterized by TGA, DTA, elemental analysis and IR spectroscopy. They exhibited good thermal oxidative stability as shown by the fact that the powders of these polymers suffered 5.4%,2.4% weight loss after isothermal aging in air at 300℃ for 200 hours.The decomposition temperature of (Ⅱ) was 583℃ in air and 590℃ in N2.These linear poly-1,3,5-triazines were soluble in concentrated sulfuric acid,phosphoric acid and trifluoroacetic acid whereas the crosslinked poly-1,3,5-triazines reported in the literature were insoluble and infusible.It is interesting that these polymers can form complexes with metal halides as determined by X-ray photoelectron spectroscopy(XPS).The polymer metal complex(Ⅲ).PdCl2 possesses catalytic activity for hydrogenation.
1984, 2(2): 124-130
Abstract:
Segmented polyurethanes (SPU) have been used as an important biomedical material, of which the hemocompatibility is determined mainly by the surface properties of the polymer. ESCA has. been used in the present study to characterize the surface composition of SPU samples with different degree of phase segregation. Our experimental results show that (1) the ratio of O/N on polymer-air interface is greater than that in the bulk, i. e., more soft segment is found on the surface than in the bulk average; (2) the soft segment is more abundant on the surface for the sample with better phase segregation;(3)within about 50A thickness of the air facing side the composition variation of the sample with better phase segregation is greater than the sample with poor phase segregation.
Segmented polyurethanes (SPU) have been used as an important biomedical material, of which the hemocompatibility is determined mainly by the surface properties of the polymer. ESCA has. been used in the present study to characterize the surface composition of SPU samples with different degree of phase segregation. Our experimental results show that (1) the ratio of O/N on polymer-air interface is greater than that in the bulk, i. e., more soft segment is found on the surface than in the bulk average; (2) the soft segment is more abundant on the surface for the sample with better phase segregation;(3)within about 50A thickness of the air facing side the composition variation of the sample with better phase segregation is greater than the sample with poor phase segregation.
1984, 2(2): 131-137
Abstract:
The active center concentration Cp, the rate constant kp, and the activation energy of chain propagation Ep in the polymerization of propylene with complex-type TiCl3-(C2H5)2AlCl catalyst system were studied. The Mn was corrected by Mw/Mn value determined by GPC. The values thus obtained for Cp, kp, and Ep at 50℃ were 3.01 mol/mol Ti, 6.27 1/mol·sec, and 5.10 Kcal/mol respectively. The kinetic parameters were compared with those obtained from conventional TiCl3·AlCl2 catalyst, showing that the higher activity of the complex-type catalyst over the conventional catalyst is not only due to the higher Cp of the former,but to a greater extent due to the increase of the kp value.
The active center concentration Cp, the rate constant kp, and the activation energy of chain propagation Ep in the polymerization of propylene with complex-type TiCl3-(C2H5)2AlCl catalyst system were studied. The Mn was corrected by Mw/Mn value determined by GPC. The values thus obtained for Cp, kp, and Ep at 50℃ were 3.01 mol/mol Ti, 6.27 1/mol·sec, and 5.10 Kcal/mol respectively. The kinetic parameters were compared with those obtained from conventional TiCl3·AlCl2 catalyst, showing that the higher activity of the complex-type catalyst over the conventional catalyst is not only due to the higher Cp of the former,but to a greater extent due to the increase of the kp value.
1984, 2(2): 138-145
Abstract:
Based on the methods reported by Ambler and Kraus, a method has been developed for the determination of long-chain branching distribution in polymers by the combined use of GPC and intrinsic viscosity data of polymer fractions. In this method, gi, λi, Gi, mi, the weight percentage of polymer that is branched, etc. can be used simultaneously to characterize the distribution, degree and content of branching in polymers. Some relations between molecular weight polydispersity and branching polydispersity in Nickel-based high cis-1,4-polybutadiene samples are discussed.It was found that the number of long branchedλ per unit molecular weight is a function of molecular weight and all of the samples are highly branched at a molecular weight of about 106.
Based on the methods reported by Ambler and Kraus, a method has been developed for the determination of long-chain branching distribution in polymers by the combined use of GPC and intrinsic viscosity data of polymer fractions. In this method, gi, λi, Gi, mi, the weight percentage of polymer that is branched, etc. can be used simultaneously to characterize the distribution, degree and content of branching in polymers. Some relations between molecular weight polydispersity and branching polydispersity in Nickel-based high cis-1,4-polybutadiene samples are discussed.It was found that the number of long branchedλ per unit molecular weight is a function of molecular weight and all of the samples are highly branched at a molecular weight of about 106.
1984, 2(2): 146-151
Abstract:
An automatic capillary viscometer with optical fibres as cold light source and a thermostat in which the temperature can be regulated within ±5×10-4℃ have been developed for the determination of flow time with an accuracy of ±4×10-3 sec. The basic principle, construction, specifications as well as the main features of this instrument are described.
An automatic capillary viscometer with optical fibres as cold light source and a thermostat in which the temperature can be regulated within ±5×10-4℃ have been developed for the determination of flow time with an accuracy of ±4×10-3 sec. The basic principle, construction, specifications as well as the main features of this instrument are described.
1984, 2(2): 151-158
Abstract:
Polymeric pendant Ru(bpy)32+ complexes were prepared from homopolymer and copolymers of 4-methyl-4'-vinyl-2,2'-bipyridine (Vbpy). Vbpy was prepared from 4-methylpyridine. The comonomers were styrene (St), acrylic acid (AA), N-vinylpyrrolidone (Pyr), 4-vinylpyridine (Vpy), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), acrylonitrile (AN) and N-ethyl-4-vinylpyridium bromide (EQ-Vpy). The fraction of the pendant Ru(bpy)32+ repeating unit in the polymeric complex was 0.022 to 0.052. Absorption maximum,molar extinction coefficient,emission maximum and relative emission intensity of the polymeric complexes were studied.
Polymeric pendant Ru(bpy)32+ complexes were prepared from homopolymer and copolymers of 4-methyl-4'-vinyl-2,2'-bipyridine (Vbpy). Vbpy was prepared from 4-methylpyridine. The comonomers were styrene (St), acrylic acid (AA), N-vinylpyrrolidone (Pyr), 4-vinylpyridine (Vpy), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), acrylonitrile (AN) and N-ethyl-4-vinylpyridium bromide (EQ-Vpy). The fraction of the pendant Ru(bpy)32+ repeating unit in the polymeric complex was 0.022 to 0.052. Absorption maximum,molar extinction coefficient,emission maximum and relative emission intensity of the polymeric complexes were studied.
1984, 2(2): 159-168
Abstract:
Macroporous HA resins (HAR) can be prepared in pearl form by grafting HA onto crosslinked PS through azo or through ester and / or ether linkages. At pH 13 and the HA / PSNH2 weight ratio 0.7—1.0, PSN2+Cl-couples with HA and results in the formation of a7o-type HA resin (HAR-A), which shows good adsorbility towards heavy metal ions. The Cu2+ sorption capacity of ester / ether type humic acid resin (HAR-E) is increased by lengthening the reaction time of HA and PSCH2Cl. The structure of HAR is discussed on the basis of the IR spectra.The sorption capacity of HAR-A is 1.01mmol/g for Cd2+,Mn2+,Cu2+,Co2+and Zn2+,respectively.The calculated distribution coefficents of heavy metal ions on HAR-A can be arranged in the following order;Cu2+(8.7×103)>Cd2(3.8×102)>Zn2+(2.4×102)>Ni2+(1.8×102)>Mn2+(4.9×10).At pH 6.5,Cu2+,Cd2+,Ni2+,Mn2+ can be quantitatively asdorbed by HAR-A and completely eluted with 1N HNO3.HAR-A can be regenerated and reused.Trace quantities of the above-mentioned heavy metal ions in four samples of the natural occurring water and one sample of the tap water were analyzed by using HAR-A.
Macroporous HA resins (HAR) can be prepared in pearl form by grafting HA onto crosslinked PS through azo or through ester and / or ether linkages. At pH 13 and the HA / PSNH2 weight ratio 0.7—1.0, PSN2+Cl-couples with HA and results in the formation of a7o-type HA resin (HAR-A), which shows good adsorbility towards heavy metal ions. The Cu2+ sorption capacity of ester / ether type humic acid resin (HAR-E) is increased by lengthening the reaction time of HA and PSCH2Cl. The structure of HAR is discussed on the basis of the IR spectra.The sorption capacity of HAR-A is 1.01mmol/g for Cd2+,Mn2+,Cu2+,Co2+and Zn2+,respectively.The calculated distribution coefficents of heavy metal ions on HAR-A can be arranged in the following order;Cu2+(8.7×103)>Cd2(3.8×102)>Zn2+(2.4×102)>Ni2+(1.8×102)>Mn2+(4.9×10).At pH 6.5,Cu2+,Cd2+,Ni2+,Mn2+ can be quantitatively asdorbed by HAR-A and completely eluted with 1N HNO3.HAR-A can be regenerated and reused.Trace quantities of the above-mentioned heavy metal ions in four samples of the natural occurring water and one sample of the tap water were analyzed by using HAR-A.
1984, 2(2): 169-176
Abstract:
The morphology and structure of three types of normal and abnormal spherulites of polyethylene terephthalate cast from solution in dimethylphthalate were studied by polarizing microscopy, transmission electron microscopy and electron diffraction techniques. In the normal negative spherulites the [210]* direction is parallel to the radius direction. In the normal positive spherulites the radius direction is parallel to the [326]*. In the abnormal PET spherulites the Maltese cross extinction pattern in the polarizing microscope under crossed polars is oriented at 45°to the polars and there are concentric extinction rings around the center of the spherulite.Electron diffraction pattern indicates that[212]* is parallel to the radius of the spherulite and this explains the observed extinction pattern in the abnormal spherulite.
The morphology and structure of three types of normal and abnormal spherulites of polyethylene terephthalate cast from solution in dimethylphthalate were studied by polarizing microscopy, transmission electron microscopy and electron diffraction techniques. In the normal negative spherulites the [210]* direction is parallel to the radius direction. In the normal positive spherulites the radius direction is parallel to the [326]*. In the abnormal PET spherulites the Maltese cross extinction pattern in the polarizing microscope under crossed polars is oriented at 45°to the polars and there are concentric extinction rings around the center of the spherulite.Electron diffraction pattern indicates that[212]* is parallel to the radius of the spherulite and this explains the observed extinction pattern in the abnormal spherulite.
1984, 2(2): 177-189
Abstract:
A series of macromolecular copolymers of styrene and divinyl-benzene were prepared in the presence of iso-octanol or 2-ethyl butyl alcohol. The factors which affected the physical structures of the copolymer were discussed. The macroporous amido-phosphonic acid resin was obtained after the acetylation, phosphonylation and amination of the crosslinked polystyrene. The factors which affected each reaction were studied and the change of physical structures of the copolymer were discussed.
A series of macromolecular copolymers of styrene and divinyl-benzene were prepared in the presence of iso-octanol or 2-ethyl butyl alcohol. The factors which affected the physical structures of the copolymer were discussed. The macroporous amido-phosphonic acid resin was obtained after the acetylation, phosphonylation and amination of the crosslinked polystyrene. The factors which affected each reaction were studied and the change of physical structures of the copolymer were discussed.
1984, 2(2): 190-195
Abstract:
In this paper the synthesis of linear and crosslinked N-substituted acrylamide copolymer is reported. In order to obtain the terpolymer with appropriate hydrophilicity, the conditions of aminolysis of St-MMA copolymer have been selected. It is shown that the copolymer with predictable hydrophilicity possesses good blood compatibility.
In this paper the synthesis of linear and crosslinked N-substituted acrylamide copolymer is reported. In order to obtain the terpolymer with appropriate hydrophilicity, the conditions of aminolysis of St-MMA copolymer have been selected. It is shown that the copolymer with predictable hydrophilicity possesses good blood compatibility.
1984, 2(2): 197-202
Abstract:
The PAN fiber treated by Lewis acid (e.g. stannic chloride) could be transformed into a macromolecular conducting fiber by further thermal treatment. Depending on thermal treatment condition the resistance of the fiber varied from 103 to 1012 Ω and kept stable after hydrolysis. The fiber has enough strength to be processed by various means. This is a new kind of macromolecular semiconducting fiber having some characteristics similar to those of organic semiconductors.
The PAN fiber treated by Lewis acid (e.g. stannic chloride) could be transformed into a macromolecular conducting fiber by further thermal treatment. Depending on thermal treatment condition the resistance of the fiber varied from 103 to 1012 Ω and kept stable after hydrolysis. The fiber has enough strength to be processed by various means. This is a new kind of macromolecular semiconducting fiber having some characteristics similar to those of organic semiconductors.
1984, 2(2): 203-208
Abstract:
The polymerization kinetics of 4,4'-biphenyldicarbonitrile catalyzed by complex of 4,4'-biphenyl-dicarbonitrile with ZnCl2 was studied. The cyano group concentration was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. The results proved that the polymerization is a second order reaction, and the activation energy of polymerization is 12.4 kcal/mol. The polymerization rates of 4,4'-biphenyldicarbonitrile catalyzed by other seven complexes were also measured.The polymerization mechanism was discussed.
The polymerization kinetics of 4,4'-biphenyldicarbonitrile catalyzed by complex of 4,4'-biphenyl-dicarbonitrile with ZnCl2 was studied. The cyano group concentration was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. The results proved that the polymerization is a second order reaction, and the activation energy of polymerization is 12.4 kcal/mol. The polymerization rates of 4,4'-biphenyldicarbonitrile catalyzed by other seven complexes were also measured.The polymerization mechanism was discussed.
1984, 2(2): 209-212
Abstract:
It has been shown that the free volume fraction at Tg is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at Tg is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at Tg and energy e of rotational isomerization of isolated molecular chains was formulated,e=-k·Tg·1n(Δa·Tg/1-Δa·Tg).The values of calculated from the above formula are in good agreement with those published in the literatures.Thus,the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.7
It has been shown that the free volume fraction at Tg is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at Tg is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at Tg and energy e of rotational isomerization of isolated molecular chains was formulated,e=-k·Tg·1n(Δa·Tg/1-Δa·Tg).The values of calculated from the above formula are in good agreement with those published in the literatures.Thus,the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.7
1984, 2(2): 213-216
Abstract:
Continuing the study of electron transfer reactions of polypyridiniomethylstyrene chloride (PSPyCl), the reduction of nitro-compounds by the PSPyCl-Zn system was investigated. In general azoxy compounds were obtained as chief intermediate product of reduction. Reduction of nitrobenzo-15-crown-5 and its homologues give a new class of bis-crown ether compounds——azoxy-bisbenzocrown ethers. Azoxybisbenzocrown ethers undergo photoinduced trans-cis isomerization, which is reversible on irradiation with UV and on storage in darkness,similar to the case of azobis crows ethers.Investigation of solvent extraction of various cations by azobiscrown ether isomers shows that cis-azoxybisbenzo-15-crown-5 exhibit good selectivity toward Nd3+ from other rare earth cations.
Continuing the study of electron transfer reactions of polypyridiniomethylstyrene chloride (PSPyCl), the reduction of nitro-compounds by the PSPyCl-Zn system was investigated. In general azoxy compounds were obtained as chief intermediate product of reduction. Reduction of nitrobenzo-15-crown-5 and its homologues give a new class of bis-crown ether compounds——azoxy-bisbenzocrown ethers. Azoxybisbenzocrown ethers undergo photoinduced trans-cis isomerization, which is reversible on irradiation with UV and on storage in darkness,similar to the case of azobis crows ethers.Investigation of solvent extraction of various cations by azobiscrown ether isomers shows that cis-azoxybisbenzo-15-crown-5 exhibit good selectivity toward Nd3+ from other rare earth cations.
