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1997 Volume 15 Issue 4
1997, 15(4): 289-294
Abstract:
Some physical properties of the polyester-polyeher multiblock copolymers with Si-containing hard segment were further examined by a series of physical methods. Thehydrophobicity of the copolymers was improved with the incorporation of increasing amountof organosilicone, XPS test proved that silicon element was enriched at the surface of theSi-containing polyeser-polyether copolymers. It was also found that their heat resistanceand gas permeability for O2 and N2 were greatly improved.The study on semipermeability of films made of the Si-containing copolymers was also followed with interest.
Some physical properties of the polyester-polyeher multiblock copolymers with Si-containing hard segment were further examined by a series of physical methods. Thehydrophobicity of the copolymers was improved with the incorporation of increasing amountof organosilicone, XPS test proved that silicon element was enriched at the surface of theSi-containing polyeser-polyether copolymers. It was also found that their heat resistanceand gas permeability for O2 and N2 were greatly improved.The study on semipermeability of films made of the Si-containing copolymers was also followed with interest.
1997, 15(4): 295-304
Abstract:
The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chain could even be stabilized in various values.It therefore indicates that the intermolecular interaction does play a considerable role for this polymer forming the conformation.Ac ccording to cohesive energies calculated for these unit cell models,the torsion angle in the most stable crystalline cell in 0°.When the chains packing together,there exist so many energy stable wells along the chain axis 0.35-0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies.These factors thus cause the difficulty of forming an unique perfect crystalline structure of the polymer.The present study suggested a number of reasonable unit cells,and the most stable crystalline structure for this polymer that is monoclinic,non-primitive unit cell.
The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chain could even be stabilized in various values.It therefore indicates that the intermolecular interaction does play a considerable role for this polymer forming the conformation.Ac ccording to cohesive energies calculated for these unit cell models,the torsion angle in the most stable crystalline cell in 0°.When the chains packing together,there exist so many energy stable wells along the chain axis 0.35-0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies.These factors thus cause the difficulty of forming an unique perfect crystalline structure of the polymer.The present study suggested a number of reasonable unit cells,and the most stable crystalline structure for this polymer that is monoclinic,non-primitive unit cell.
1997, 15(4): 305-310
Abstract:
Urushiol polymer containing B--N bond (PUBN) was synthesized with urushiol-boronpolymer and diethylene triamine. Its structure was characterized by XPS, IR, UV, HPLC,DTA-TG and elemental analysis. The physico-mechanical and anticorrosive propertiesof the polymer were also investigated. The results show that the coating of PUBN canbe hardened in 2h at room temperaure and its film has excellent physico-mechanicalproperties and good anticorrosive properties.
Urushiol polymer containing B--N bond (PUBN) was synthesized with urushiol-boronpolymer and diethylene triamine. Its structure was characterized by XPS, IR, UV, HPLC,DTA-TG and elemental analysis. The physico-mechanical and anticorrosive propertiesof the polymer were also investigated. The results show that the coating of PUBN canbe hardened in 2h at room temperaure and its film has excellent physico-mechanicalproperties and good anticorrosive properties.
1997, 15(4): 311-318
Abstract:
A branched polyethyleneimine (BPEI) was applied to poly(ethylene terephthalate)(PET) fabric to improve its surface moisture absorption so that the fabric becomes lessliable to retention of electrostatic charg. The durability of this treatment was assessed bywashing and followed by measurement of charge development on the fabric. The treatedsamples showed improved surface wetting compared to the untreated. The results areconsistent with attachment of the BPEI to the PET surface by a cross-linking mechanism.
A branched polyethyleneimine (BPEI) was applied to poly(ethylene terephthalate)(PET) fabric to improve its surface moisture absorption so that the fabric becomes lessliable to retention of electrostatic charg. The durability of this treatment was assessed bywashing and followed by measurement of charge development on the fabric. The treatedsamples showed improved surface wetting compared to the untreated. The results areconsistent with attachment of the BPEI to the PET surface by a cross-linking mechanism.
1997, 15(4): 319-324
Abstract:
A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, and water vapor are progressively increased,caused by decrease in crystalline fraction and increase in free volume of VDC/MA copolymers.
A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, and water vapor are progressively increased,caused by decrease in crystalline fraction and increase in free volume of VDC/MA copolymers.
1997, 15(4): 325-331
Abstract:
Some nove polyimides containing bisthiazole rings were prepared by reacting 2,2'-diamino-4, 4'-bisthiazole (DABT) with different aromatic dianhydride. The polyimidesobtained had inherent viscosities of 0.37--0.82 dl/g. Thermogravimetric analysis of thepolyimides showed good thermal stability the temperature at 5% weight loss being from450°to 560℃. The permeability of two polymer membranes to H2, O2 and N2 was deter-mined, respectively Three kinds of polyimide films were converted into electrical conductor by pyrolysis at high temperature in nitrogen atmosphere.The maximum room temperature conductivity as high as 3.9×102S/cm for PI film pyrolyzed at 1200℃ for 10 min was obtained,and it was very stable in air.
Some nove polyimides containing bisthiazole rings were prepared by reacting 2,2'-diamino-4, 4'-bisthiazole (DABT) with different aromatic dianhydride. The polyimidesobtained had inherent viscosities of 0.37--0.82 dl/g. Thermogravimetric analysis of thepolyimides showed good thermal stability the temperature at 5% weight loss being from450°to 560℃. The permeability of two polymer membranes to H2, O2 and N2 was deter-mined, respectively Three kinds of polyimide films were converted into electrical conductor by pyrolysis at high temperature in nitrogen atmosphere.The maximum room temperature conductivity as high as 3.9×102S/cm for PI film pyrolyzed at 1200℃ for 10 min was obtained,and it was very stable in air.
1997, 15(4): 332-337
Abstract:
Rubber of high molar mass, like cis-polybutadiene, shows a stress peak on theenineering stress-strain curve during stretching at room temperature. In this work cis-polybutadiene samples were swollen in a poor solvent, CHCl3/EtOH (1/1 v/v), for differenttimes. It was found that both the initial modulus and the stress peak on stretching de-creased in magnitude with increasing swelling time and the peak disappeared entirely after1 hour of swelling. On further swelling the initial modulus increased somewhat and a small stress peak re-appeared after swelling for 2h.The disappearance of the stress peak after swelling is interpreted as the result of disruption of cohesional entanglements present in the initial rubber sample.The re-appearence of a small stress peak and the increase of modulus on further swelling are interpreted as being of the same nature as the phenomenon of anti-plasticization.It is the result of forming some new cohesional entanglements of larger binding energies through longer range chain segmental motions excited after the disruption of the previously existing cohesional entanglements in the rubber.Thus an understanding of the stress peak on stretching a high molar mass rubber and the phenomenon of anti-plasticization on molecular level has been put forward.
Rubber of high molar mass, like cis-polybutadiene, shows a stress peak on theenineering stress-strain curve during stretching at room temperature. In this work cis-polybutadiene samples were swollen in a poor solvent, CHCl3/EtOH (1/1 v/v), for differenttimes. It was found that both the initial modulus and the stress peak on stretching de-creased in magnitude with increasing swelling time and the peak disappeared entirely after1 hour of swelling. On further swelling the initial modulus increased somewhat and a small stress peak re-appeared after swelling for 2h.The disappearance of the stress peak after swelling is interpreted as the result of disruption of cohesional entanglements present in the initial rubber sample.The re-appearence of a small stress peak and the increase of modulus on further swelling are interpreted as being of the same nature as the phenomenon of anti-plasticization.It is the result of forming some new cohesional entanglements of larger binding energies through longer range chain segmental motions excited after the disruption of the previously existing cohesional entanglements in the rubber.Thus an understanding of the stress peak on stretching a high molar mass rubber and the phenomenon of anti-plasticization on molecular level has been put forward.
1997, 15(4): 338-346
Abstract:
The kinetic behavior of isohermal and nonisothermal crystallization of nylon-1010has been studied by means of dilatometry and differential scanning calorimetry, respec-tively. The isothermal and nonisothermal process can be descibed by Avrami equationand Ozawa equation, respectively. From the experimental results the kinetic paramters ofcrystallization and crystalline mechanism for isothermal and nonisothermal measurementsare discussed.
The kinetic behavior of isohermal and nonisothermal crystallization of nylon-1010has been studied by means of dilatometry and differential scanning calorimetry, respec-tively. The isothermal and nonisothermal process can be descibed by Avrami equationand Ozawa equation, respectively. From the experimental results the kinetic paramters ofcrystallization and crystalline mechanism for isothermal and nonisothermal measurementsare discussed.
1997, 15(4): 347-352
Abstract:
Some organogermanium oligomers with different side groups were synthesized via li-gand substitution polymerization from 1, 4-dioxane complex of germanium dichloride withdifferent organolithitum compounds. The oligomers were isolated through either precipi-tation from methanol or extraction using toluene with a yield of no less than 50%. Theweiglit average molecular weight (Mw) of the oligomers is ranging from 1.4×103 to 5.9×103 depending on the type and alkyl length of the organolithium compounds used.
Some organogermanium oligomers with different side groups were synthesized via li-gand substitution polymerization from 1, 4-dioxane complex of germanium dichloride withdifferent organolithitum compounds. The oligomers were isolated through either precipi-tation from methanol or extraction using toluene with a yield of no less than 50%. Theweiglit average molecular weight (Mw) of the oligomers is ranging from 1.4×103 to 5.9×103 depending on the type and alkyl length of the organolithium compounds used.
1997, 15(4): 353-361
Abstract:
A series of novel mesogenic polyamides containing a flexible pendent side group wassynthesized by solution condensation polymerization. The new monomers, diacids and di-amines containing flexible elements of diferent lengths, were also synthesized and character-ized by ~1HNMR, mass spectroscopy and elemental analysis. The polymers were character-ized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffiactionand polarizing optical microscopy. These studies revealed that polyamides containing flexible elements of a sufficient length exhibited thermotropic liquid crystalline (LC) properties.The melting temperatures of this series of polymers were particularly sensitive to the length of the flexible segment on the main chain and that of the flexible pendent ester side chain.Lyotropic LC behaviours were also observed in solution.
A series of novel mesogenic polyamides containing a flexible pendent side group wassynthesized by solution condensation polymerization. The new monomers, diacids and di-amines containing flexible elements of diferent lengths, were also synthesized and character-ized by ~1HNMR, mass spectroscopy and elemental analysis. The polymers were character-ized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffiactionand polarizing optical microscopy. These studies revealed that polyamides containing flexible elements of a sufficient length exhibited thermotropic liquid crystalline (LC) properties.The melting temperatures of this series of polymers were particularly sensitive to the length of the flexible segment on the main chain and that of the flexible pendent ester side chain.Lyotropic LC behaviours were also observed in solution.
1997, 15(4): 362-367
Abstract:
Polyfluoroalkyl substituted 2-hydroxyethyl acrylate 6 was synthesized in six steps usingglycerol as a starting material. A preliminary investigation has been taken on the synthesisand characterization of copolymers of 6 and 2-hydroxyethyl methacrylate.
Polyfluoroalkyl substituted 2-hydroxyethyl acrylate 6 was synthesized in six steps usingglycerol as a starting material. A preliminary investigation has been taken on the synthesisand characterization of copolymers of 6 and 2-hydroxyethyl methacrylate.
1997, 15(4): 368-372
Abstract:
Tapping mode atomic force microscope has been applied to observe single-chain PMMAparticles which were stored for six months at room temperature after sprayed from verydilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodis-perse PMMA standards of molecular weights ranging from 7.90×104 to 1.3×106 wereused to investigate the effect of molecular weight oh the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight was found to be identical in spite of different solvents used for solution spraying.Molecular weight dependence of the particle dimension was also found.The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared to the values estimated from molecular weight and density.
Tapping mode atomic force microscope has been applied to observe single-chain PMMAparticles which were stored for six months at room temperature after sprayed from verydilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodis-perse PMMA standards of molecular weights ranging from 7.90×104 to 1.3×106 wereused to investigate the effect of molecular weight oh the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight was found to be identical in spite of different solvents used for solution spraying.Molecular weight dependence of the particle dimension was also found.The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared to the values estimated from molecular weight and density.
1997, 15(4): 373-378
Abstract:
Phase inversion emulsification technique is a recently developed method to achievewaterborne dispersions of polymer resin. It is found that the electrica and rheologicalproperties of the system experience abrupt changes in the vicinity of the phase inversionpoint (PIP). Before PIP the system is a Newtonian fluid. At PIP the continuous phasetransforms from polymer resin to water phase with the result that the electrical resistanceof the system drops abruptly. Meanwhile, the system at PIP exhibits high visco-elasticity originated from the formation of a physical gel alike structure among the waterborne particles.Besides,the morphology evolution is observed by Scanning Electron Microscopy (SEM).
Phase inversion emulsification technique is a recently developed method to achievewaterborne dispersions of polymer resin. It is found that the electrica and rheologicalproperties of the system experience abrupt changes in the vicinity of the phase inversionpoint (PIP). Before PIP the system is a Newtonian fluid. At PIP the continuous phasetransforms from polymer resin to water phase with the result that the electrical resistanceof the system drops abruptly. Meanwhile, the system at PIP exhibits high visco-elasticity originated from the formation of a physical gel alike structure among the waterborne particles.Besides,the morphology evolution is observed by Scanning Electron Microscopy (SEM).
