Login In
1994 Volume 12 Issue 1
1994, 12(1): 1-11
Abstract:
1994, 12(1): 12-21
Abstract:
Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF (95 )/VF (5), VDF (52)/TrFE (48) and VDF(47. 5)/TrFE(47. 5)/HeFP (5) over a range of-120-140℃, 10-2-104Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chain of PVDF led to disappearing of α-relaxation and increase in Tg(3℃)of VDF (95)/VF(5).Because of the spatial impediment of 5mol% HeFP in copolymer chain,the Curie point of VDF (52)/TrFE(48)decreased by 30℃.The behavior of dielectric relaxation indicated that 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline region reduced,the activation energy of local relaxation increased and the relaxation time prolonged respectively.
Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF (95 )/VF (5), VDF (52)/TrFE (48) and VDF(47. 5)/TrFE(47. 5)/HeFP (5) over a range of-120-140℃, 10-2-104Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chain of PVDF led to disappearing of α-relaxation and increase in Tg(3℃)of VDF (95)/VF(5).Because of the spatial impediment of 5mol% HeFP in copolymer chain,the Curie point of VDF (52)/TrFE(48)decreased by 30℃.The behavior of dielectric relaxation indicated that 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline region reduced,the activation energy of local relaxation increased and the relaxation time prolonged respectively.
1994, 12(1): 22-27
Abstract:
The γ induced polymerization of styrene in the presence of polar additives such as tributylphosphate, triethyl amine and ethanol was studied at dose rate of 5.0×1017 eV/ml. min. The re-sult shows that radiation induced polymerization of styrene was sensitized by the three kinds ofadditives at the approximate same rate and the experimental results were in agreement with thetheoretical calculation of WAS equation. The cause of sensitization is due to the proton transfer.
The γ induced polymerization of styrene in the presence of polar additives such as tributylphosphate, triethyl amine and ethanol was studied at dose rate of 5.0×1017 eV/ml. min. The re-sult shows that radiation induced polymerization of styrene was sensitized by the three kinds ofadditives at the approximate same rate and the experimental results were in agreement with thetheoretical calculation of WAS equation. The cause of sensitization is due to the proton transfer.
1994, 12(1): 28-32
Abstract:
Copolymerization of carbon dioxide with epichlorohydrin was successfully carried out by usingNd(P204)3-Al(i-Bu)3 as catalyst (P204)=(RO)2 POO--,R=CH3 (CH2),CH(C2H5) CH2--). Addi-tion of carbonyl compounds into the catalyst decreased the carbon dioxide content of the copoly-mer to some extent. Compared to nonpolar solvents, ethereal and moderate polar solvents werefavourable to obtaining higher carbon dioxide content copolymer. The coincidence of these resultswith the assumed copolymerization scheme clearly indicated that the copolymerization proceeds via coordinate anionic mechanism.
Copolymerization of carbon dioxide with epichlorohydrin was successfully carried out by usingNd(P204)3-Al(i-Bu)3 as catalyst (P204)=(RO)2 POO--,R=CH3 (CH2),CH(C2H5) CH2--). Addi-tion of carbonyl compounds into the catalyst decreased the carbon dioxide content of the copoly-mer to some extent. Compared to nonpolar solvents, ethereal and moderate polar solvents werefavourable to obtaining higher carbon dioxide content copolymer. The coincidence of these resultswith the assumed copolymerization scheme clearly indicated that the copolymerization proceeds via coordinate anionic mechanism.
1994, 12(1): 33-43
Abstract:
The 13C T1s of --CH3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH3 sidegroup in PPU was analyzed by means of the average spectral density functions of internal rota-tion. The results showed that the rotation of the --CH3 side group is related closely to the com-patibility between the two components. The compatibility was studied by analyzing the protonspin-lattice relaxation in rotating frame, spin-spin relaxation and spin-diffusion.The results showed that the hydrogen bonds between the components play a major role in determining the compatibility.Through spin diffusion studying,the soft phase domain size was calculated.By studying proton spin-spin relaxation,the content of each component in each phase and that of each phase in the samples can be obtained.The result shows that the content of interphase is related closely to the compatibility.
The 13C T1s of --CH3 side group in PPU/P (St-co-AA), AB-crosslinked polymers (i. e.ABCP) was studied by using high resolution solid state NMR. The rotation motion of --CH3 sidegroup in PPU was analyzed by means of the average spectral density functions of internal rota-tion. The results showed that the rotation of the --CH3 side group is related closely to the com-patibility between the two components. The compatibility was studied by analyzing the protonspin-lattice relaxation in rotating frame, spin-spin relaxation and spin-diffusion.The results showed that the hydrogen bonds between the components play a major role in determining the compatibility.Through spin diffusion studying,the soft phase domain size was calculated.By studying proton spin-spin relaxation,the content of each component in each phase and that of each phase in the samples can be obtained.The result shows that the content of interphase is related closely to the compatibility.
1994, 12(1): 44-48
Abstract:
The non-isothermal crystallization kinetics analysis of liquid crystalline random copolyestercomposed of p-oxybenzoate (B) and 2, 6-oxynaphthoate (N) monomers was carried out by meansof differential scanning calorimetry basing on Ziabicki and Jeziorny method. Although the compo-sition of 58/42 B-N copolyester had poorer thermodynamic crystallizability comparing with thoseof 30/70 and 75/25, its kinetic crystallizability Go was slightly larger. This fact was due to thepoorer match of sequences of 58/42 B-N in domains of nematic melt,and therefore better mobility of chains during crystallization.The Avrami exponents of three composition species were all about 2.5,implying two dimensional growth in so-called non-periodic layer crystallites and a mixture of homogeneous and heterogenous nucleation.
The non-isothermal crystallization kinetics analysis of liquid crystalline random copolyestercomposed of p-oxybenzoate (B) and 2, 6-oxynaphthoate (N) monomers was carried out by meansof differential scanning calorimetry basing on Ziabicki and Jeziorny method. Although the compo-sition of 58/42 B-N copolyester had poorer thermodynamic crystallizability comparing with thoseof 30/70 and 75/25, its kinetic crystallizability Go was slightly larger. This fact was due to thepoorer match of sequences of 58/42 B-N in domains of nematic melt,and therefore better mobility of chains during crystallization.The Avrami exponents of three composition species were all about 2.5,implying two dimensional growth in so-called non-periodic layer crystallites and a mixture of homogeneous and heterogenous nucleation.
1994, 12(1): 49-56
Abstract:
Three polystyrene resins containing polyether oligomers as extractants were synthesized andtheir extraction properties were studied. Gold (III) ion could be extracted rapidly by the resins(T1/2<1min.)with high effciency and capacity (for LS-B resin that were 99.8% and 95.8mg/gR respectively) from aqueous solution but most of the co-existing metal ions such as Pd(II),Cu(II),Zn(II),Pd(II) and Cd(II) were remained.The extraction capacity and stripping percentage for gold (Ⅲ) remained unmained unchanged in four extraction-stripping cycles.The resins also showed good column extraction-elution properties.
Three polystyrene resins containing polyether oligomers as extractants were synthesized andtheir extraction properties were studied. Gold (III) ion could be extracted rapidly by the resins(T1/2<1min.)with high effciency and capacity (for LS-B resin that were 99.8% and 95.8mg/gR respectively) from aqueous solution but most of the co-existing metal ions such as Pd(II),Cu(II),Zn(II),Pd(II) and Cd(II) were remained.The extraction capacity and stripping percentage for gold (Ⅲ) remained unmained unchanged in four extraction-stripping cycles.The resins also showed good column extraction-elution properties.
1994, 12(1): 57-65
Abstract:
A discussion of the mechanism of nylon 6, 6 dissolving process using CaCl2/MeOH as the sol-vent is presented. The calcium chloride forms a complex compound with nylon 6, 6 by breakingthe hydrogen bonds. The melting point of the CaCl2 --nylon 6, 6 complex was found to be reducedby 91K relative to the pure nylon 6, 6 polymer. The role of methanol is somewhat similar to acatalyst. The results demonstrate that the complexation of a Lewis acid (CaCl2) and a Lewis base(nylon 6, 6) can be used to probe intermolecular interactions such as hydrogen bonding in polymers,to modify the polymer properties and mediate its solubility and processing.
A discussion of the mechanism of nylon 6, 6 dissolving process using CaCl2/MeOH as the sol-vent is presented. The calcium chloride forms a complex compound with nylon 6, 6 by breakingthe hydrogen bonds. The melting point of the CaCl2 --nylon 6, 6 complex was found to be reducedby 91K relative to the pure nylon 6, 6 polymer. The role of methanol is somewhat similar to acatalyst. The results demonstrate that the complexation of a Lewis acid (CaCl2) and a Lewis base(nylon 6, 6) can be used to probe intermolecular interactions such as hydrogen bonding in polymers,to modify the polymer properties and mediate its solubility and processing.
1994, 12(1): 66-72
Abstract:
The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.
The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.
1994, 12(1): 73-79
Abstract:
This paper deals with graft copolymerization of acrylic acid (AA) onto Xinjiang fine wool.fiber in aqueous medium initiated by gamma rays. Graft copolymerization was carried out by themutual irradiation method in limited air. Percent grafting and percent efficiency have been deter-mined as a function of total dose, dose rate, concentration of monomer, wool weight and reactiontemperature. Graft copolymers are characterized with infrared (IR) spectroscopy, scanning elec-tron microscopy (SEM), and X--ray diffractometer,Properties of the grafts were studied,and compared with the virgin fiber.
This paper deals with graft copolymerization of acrylic acid (AA) onto Xinjiang fine wool.fiber in aqueous medium initiated by gamma rays. Graft copolymerization was carried out by themutual irradiation method in limited air. Percent grafting and percent efficiency have been deter-mined as a function of total dose, dose rate, concentration of monomer, wool weight and reactiontemperature. Graft copolymers are characterized with infrared (IR) spectroscopy, scanning elec-tron microscopy (SEM), and X--ray diffractometer,Properties of the grafts were studied,and compared with the virgin fiber.
1994, 12(1): 80-86
Abstract:
The kinetic data of solid state polycondensation of PET and its copolymers are determined.It is shown that the reaction rate of copolycondensation is higher than that of PET polyconden-sation, and increases with the comonomers content. But the reaction rate of copolycondensationin melt state of this kind of copolymers is lower than that of PET. It is considered that the chemi-cal reactivity of comonomer is the main factor which affect the polycondensation in melt state,whereas the aggregative structure of the polymer is the main factor in solid state.The crystallinity and crystallite size of the copolymers have been measured by X-ray method.
The kinetic data of solid state polycondensation of PET and its copolymers are determined.It is shown that the reaction rate of copolycondensation is higher than that of PET polyconden-sation, and increases with the comonomers content. But the reaction rate of copolycondensationin melt state of this kind of copolymers is lower than that of PET. It is considered that the chemi-cal reactivity of comonomer is the main factor which affect the polycondensation in melt state,whereas the aggregative structure of the polymer is the main factor in solid state.The crystallinity and crystallite size of the copolymers have been measured by X-ray method.
1994, 12(1): 87-90
Abstract:
Dilute solution behavior of chitosan was studied in formic acid, acetic acid, lactic acid andhydrochloric acid aqueous solution under different pH values. The reduced viscosities, ηsp/C,ofchitosan solutions were dependent on the properties of acid and pH value of solvents. For a givenchitosan concentration, ηsp/C decreased with the increase of acid concentration, or decreasing pHof solvent, indicating shielding effect of excessive acid similar to adding salt into solution. The stabilities of dilute chitosan solution in formic acid and lactic acid were better than that in acetic acid and hydrochloric acid.
Dilute solution behavior of chitosan was studied in formic acid, acetic acid, lactic acid andhydrochloric acid aqueous solution under different pH values. The reduced viscosities, ηsp/C,ofchitosan solutions were dependent on the properties of acid and pH value of solvents. For a givenchitosan concentration, ηsp/C decreased with the increase of acid concentration, or decreasing pHof solvent, indicating shielding effect of excessive acid similar to adding salt into solution. The stabilities of dilute chitosan solution in formic acid and lactic acid were better than that in acetic acid and hydrochloric acid.
1994, 12(1): 91-97
Abstract:
Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational viscometer.Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.
Cure characteristics of hydroxyl terminated polybutadiene (HTPB) prepolymer with avariety of blocked toluene diisocyanate (TDI) in the presence of triethylamine (TEA) andchloroacetic acid catalyst are reported. Phenol, thiophenol, p-chloropheno1, p-nitrophenol,p-cresol, resorcinol, naphthols, caprolactam and butylated-hydroxytoluene were used as blockingagents. Viscosity measurements have been carried out using a mixture of HTPB and blocked TDIin cyclohexanone in the presence of the catalysts at 50℃ and 60℃ using Haake rotational viscometer.Viscosity measurements have also been carried out with 50% solids such as ammonium sulphate along with HTPB and TDI adduct.
