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1992 Volume 10 Issue 3
1992, 10(3): 195-202
Abstract:
Advances have been made in understanding the interactions of composition, molecular weight, liquid crystallinity,orientation, and three-dimensional crystallinity on the properties of injection-molded and melt-spun liquid crystalline polyesters (LCP's). Two classes of potentially low-cost LCP's were compared:(1) semiflexible LCP's prepared from 1,6-hexanediol and the dimethyl ester of either trans-4, 4'stilbenedicarboxylic acid or 4.4 ' biphenyldicarboxylic acid and (2) all-aromatic LCP's prepared from terephthalic acid,2,6-naphthalenedicarboxylic acid,the diacetate of hydroquinone,and the acetate of p-hydroxybenzoic acid.The effects of composition on the plastic properties of the 4-component all-aromatic LCP's were determined with the aid of a 3×3 dactorial statistically designed experiment,the generation of equations with a computer program,and the plotting of three-dimensional figures and contour diagrams.The effects of obsolute molecular weight(Mw) on the tensile strengths of the semiflexible LCP's and one of the all-aromatic LCP's having an excellent balance of plastic properties were also compared,and it was observed that the semiflexible LCP's required Mm's about 4 times higher than the all-aromatic LCP to attain a given strength.Persistence lengths and molecular modeling were used to explain these differences.
Advances have been made in understanding the interactions of composition, molecular weight, liquid crystallinity,orientation, and three-dimensional crystallinity on the properties of injection-molded and melt-spun liquid crystalline polyesters (LCP's). Two classes of potentially low-cost LCP's were compared:(1) semiflexible LCP's prepared from 1,6-hexanediol and the dimethyl ester of either trans-4, 4'stilbenedicarboxylic acid or 4.4 ' biphenyldicarboxylic acid and (2) all-aromatic LCP's prepared from terephthalic acid,2,6-naphthalenedicarboxylic acid,the diacetate of hydroquinone,and the acetate of p-hydroxybenzoic acid.The effects of composition on the plastic properties of the 4-component all-aromatic LCP's were determined with the aid of a 3×3 dactorial statistically designed experiment,the generation of equations with a computer program,and the plotting of three-dimensional figures and contour diagrams.The effects of obsolute molecular weight(Mw) on the tensile strengths of the semiflexible LCP's and one of the all-aromatic LCP's having an excellent balance of plastic properties were also compared,and it was observed that the semiflexible LCP's required Mm's about 4 times higher than the all-aromatic LCP to attain a given strength.Persistence lengths and molecular modeling were used to explain these differences.
1992, 10(3): 203-209
Abstract:
The permeability of copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane for twelve gases (02, N2, CO2, H2, D2, He, At, CH4, C2H4, C2H6, C3H6 and C3H8) was examined. The basic laws of solution and diffusion of the gases in the membrane were expounded preliminarily. It was found that a linear relationship between logarithm of diffusion coefficient (D) and critical molar volume (Vc) of the gases. The permeation characteristics of the gases in the copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-propyne) membrane was also discussed.
The permeability of copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane for twelve gases (02, N2, CO2, H2, D2, He, At, CH4, C2H4, C2H6, C3H6 and C3H8) was examined. The basic laws of solution and diffusion of the gases in the membrane were expounded preliminarily. It was found that a linear relationship between logarithm of diffusion coefficient (D) and critical molar volume (Vc) of the gases. The permeation characteristics of the gases in the copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-propyne) membrane was also discussed.
1992, 10(3): 210-217
Abstract:
This paper reports mainly the preparation of silica supported acetylacetone ligands and their cobalt complexes, the characterization of their chemical structure, and the evaluation of their catalytic activity in the reaction for the preparation of ethers directly from alkanols and benzyl chloride. The results indicate that those silica supported β-diketone cobalt complexes (SACO) not only can simplify the reaction procedure of the ether preparation but also show a much higher catalytic activity in comparison with other honogeneous catalysts.In addition,SACO can be recovered and reused although their catalytic activity descend gradually as a result of the decrease in their cobalt content.
This paper reports mainly the preparation of silica supported acetylacetone ligands and their cobalt complexes, the characterization of their chemical structure, and the evaluation of their catalytic activity in the reaction for the preparation of ethers directly from alkanols and benzyl chloride. The results indicate that those silica supported β-diketone cobalt complexes (SACO) not only can simplify the reaction procedure of the ether preparation but also show a much higher catalytic activity in comparison with other honogeneous catalysts.In addition,SACO can be recovered and reused although their catalytic activity descend gradually as a result of the decrease in their cobalt content.
1992, 10(3): 218-222
Abstract:
Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex based on the resultant copolymer was investigated. The introduction of the polar constituent raises chain rigidity, retards crystallization of oligo(oxyethylene) domain and promotes the dissociation of lithium salt. The factors work on the mechanical and conduction properties synergistically, therefore both of the properties are improved simultaneously as the consequence of acrylamide-introduction.
Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex based on the resultant copolymer was investigated. The introduction of the polar constituent raises chain rigidity, retards crystallization of oligo(oxyethylene) domain and promotes the dissociation of lithium salt. The factors work on the mechanical and conduction properties synergistically, therefore both of the properties are improved simultaneously as the consequence of acrylamide-introduction.
1992, 10(3): 223-229
Abstract:
Ringlike polar monomer maleic, anhydride (MAn) was copolymerized with oligo (oxyethylene) methacrylate (MEOn), and its effect on ion conduction property of the corresponding polymer-salt complexes was studied. As a consequence the introduction of MAn onto polymer chain retards crystallization of the ether pendants considerably, and improves the ion conductivity to a larger degree compared with other polar groups once investigated (σmax,25℃=8.5×10-5 S/cm). The structure-ion conduction relation in the polymer-salt matrix is also analyzed macroscopically through the correspondence between composition-dependences of polymerization conversion and isothermal ion conductivity,and microscopically through the measurements of cross polarized light and electron trans-mission.
Ringlike polar monomer maleic, anhydride (MAn) was copolymerized with oligo (oxyethylene) methacrylate (MEOn), and its effect on ion conduction property of the corresponding polymer-salt complexes was studied. As a consequence the introduction of MAn onto polymer chain retards crystallization of the ether pendants considerably, and improves the ion conductivity to a larger degree compared with other polar groups once investigated (σmax,25℃=8.5×10-5 S/cm). The structure-ion conduction relation in the polymer-salt matrix is also analyzed macroscopically through the correspondence between composition-dependences of polymerization conversion and isothermal ion conductivity,and microscopically through the measurements of cross polarized light and electron trans-mission.
1992, 10(3): 230-235
Abstract:
From Wide-Angle X-ray Scattering (WAXS) pattern of uniaxially orientated fibers, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallizes in the triclinic system, with lattice dimensions: a=4.9A, b=5.4A, c=27.8, α=49 °, β=77 °,γ=63.5 °, the unit cell contains one monomeric unit and the space group is P. The degree of crystallinity of polymer was deter mined as about 60%, using Ruland's method.The structures of Nylon-1010 with different draw ratio have been investigated by using Small-Angle X-ray Scattering (SAXS).The results indicate that the draw ratio of samples has a significant effect on microstructure of Nylon-1010.The long period and thickness of amorphous layer obviously increase but the invariant,average lamellar and interphase zone show almost independent of draw ratio,long period increases because amorphous layer increases with draw ratio.The electron density fluctuation values increased with draw ratio,but inner surface Os is drecreased.
From Wide-Angle X-ray Scattering (WAXS) pattern of uniaxially orientated fibers, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallizes in the triclinic system, with lattice dimensions: a=4.9A, b=5.4A, c=27.8, α=49 °, β=77 °,γ=63.5 °, the unit cell contains one monomeric unit and the space group is P. The degree of crystallinity of polymer was deter mined as about 60%, using Ruland's method.The structures of Nylon-1010 with different draw ratio have been investigated by using Small-Angle X-ray Scattering (SAXS).The results indicate that the draw ratio of samples has a significant effect on microstructure of Nylon-1010.The long period and thickness of amorphous layer obviously increase but the invariant,average lamellar and interphase zone show almost independent of draw ratio,long period increases because amorphous layer increases with draw ratio.The electron density fluctuation values increased with draw ratio,but inner surface Os is drecreased.
1992, 10(3): 236-241
Abstract:
The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cyclohexane (CH), by homodyne photon correlation spectroscopy .The intensityintensity autocorrelation function was analyzed by the method of cumulant. The translation diffusion coefficients have been obtained as a function of temperature and concentration. Under theta condition ,the non-concentration dependence of diffiusion coefficient showed the unperturbed Gaussian state of the SPS molecular chain.The different hydrodynamic radii estimated from Stokes-Einstein equation reflected the stretch extent of the arm chain for regular star polymer.The data of diffusion activation energy of SPS in THF,BZ and CH were also obtained respectively.
The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cyclohexane (CH), by homodyne photon correlation spectroscopy .The intensityintensity autocorrelation function was analyzed by the method of cumulant. The translation diffusion coefficients have been obtained as a function of temperature and concentration. Under theta condition ,the non-concentration dependence of diffiusion coefficient showed the unperturbed Gaussian state of the SPS molecular chain.The different hydrodynamic radii estimated from Stokes-Einstein equation reflected the stretch extent of the arm chain for regular star polymer.The data of diffusion activation energy of SPS in THF,BZ and CH were also obtained respectively.
1992, 10(3): 242-249
Abstract:
The isothermal crystallization of poly (ethylene terephthalate ) (PET),which is free of catalyst, stabilizer, oligomer and diethylene glycol (DEG), was studied by DSC. The crystallization behaviour of pure PET is different from commercial PET and a reasonable explanation is presented. The influences of catalyst, stabilizer, oligomer and DEG on the crystallization of pure PET were examined. It is shown that catalyst (Manganese acetate)and stabilizer (Triphenyl phosphite) result in an increase of the crystallization rate of PET; on the contrary,DEG and oligomer (cyclotetramer) result in a reduction of the crystallization rate.When catalyst and stabilizer coexist together,both of them promote the crystallization at lower temperature,only a smaller effect was found at higher temperature,it is evident that metal phosphite is formed between the catalyst and stabilizer at higher temperature.
The isothermal crystallization of poly (ethylene terephthalate ) (PET),which is free of catalyst, stabilizer, oligomer and diethylene glycol (DEG), was studied by DSC. The crystallization behaviour of pure PET is different from commercial PET and a reasonable explanation is presented. The influences of catalyst, stabilizer, oligomer and DEG on the crystallization of pure PET were examined. It is shown that catalyst (Manganese acetate)and stabilizer (Triphenyl phosphite) result in an increase of the crystallization rate of PET; on the contrary,DEG and oligomer (cyclotetramer) result in a reduction of the crystallization rate.When catalyst and stabilizer coexist together,both of them promote the crystallization at lower temperature,only a smaller effect was found at higher temperature,it is evident that metal phosphite is formed between the catalyst and stabilizer at higher temperature.
1992, 10(3): 250-257
Abstract:
The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.
The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.
1992, 10(3): 258-265
Abstract:
The blend system composed of PET and thermotropic liquid crystal copolyester based on hydroxy benzoic acid, terephthalic acid, diacetylnaphthalene and PET was studied. The results indicated that LCP could play the role of crystal nuclei. The introduction of LCP decreased the melt viscosity of the system and fibrillous structure could be formed in favor conditions.
The blend system composed of PET and thermotropic liquid crystal copolyester based on hydroxy benzoic acid, terephthalic acid, diacetylnaphthalene and PET was studied. The results indicated that LCP could play the role of crystal nuclei. The introduction of LCP decreased the melt viscosity of the system and fibrillous structure could be formed in favor conditions.
1992, 10(3): 266-269
Abstract:
The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition.The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm,in which the dispersion force contribution is the majority.The electron diffraction proved that some crystal substance,even the single crystals were present in the polymer.X-ray diffraction also proved the presence of crystal and showed about 15% crystallinity fraction.
The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition.The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm,in which the dispersion force contribution is the majority.The electron diffraction proved that some crystal substance,even the single crystals were present in the polymer.X-ray diffraction also proved the presence of crystal and showed about 15% crystallinity fraction.
1992, 10(3): 270-275
Abstract:
The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (Rp) is Rp=9.7 x 1012 e-21.200/RT [MMA]O.88[Na2 SO3]0.50 The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ =1.2x1012e-15,600/RT[Na2SO3]=KτRi The polymerization is initiated by a primary radical generated from the redox reaction rather than induced by "coordination-proton transfer"mechanism.
The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (Rp) is Rp=9.7 x 1012 e-21.200/RT [MMA]O.88[Na2 SO3]0.50 The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ =1.2x1012e-15,600/RT[Na2SO3]=KτRi The polymerization is initiated by a primary radical generated from the redox reaction rather than induced by "coordination-proton transfer"mechanism.
1992, 10(3): 276-280
Abstract:
The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N—H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N—H to epoxide.This was accounted for the lower apparent activation energy of the curing of the two phase resin.
The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N—H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N—H to epoxide.This was accounted for the lower apparent activation energy of the curing of the two phase resin.
