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1995 Volume 13 Issue 3
1995, 13(3): 195-203
Abstract:
The principal objectives and methods of surface modification of polymers are reviewed inthis paper. The methods covered include physical, chemical, mechanical and biological.
The principal objectives and methods of surface modification of polymers are reviewed inthis paper. The methods covered include physical, chemical, mechanical and biological.
1995, 13(3): 204-209
Abstract:
The shape asymmetry of gaussian models of linear and circular macromolecules hasbeen numerically invesigated in terms of asphericity and prolateness parameters. Theseparameters are found to decrease with increasing length for the macromolecule eitherconfined to a plane or in three dimensions. The effect of dimensionality on theseparameters is visible only for low dimensions and is generally weak. As dimensionality goes to infinity, it is found that asphericity and prolateness for both chains and rings approach slowly yet descendingly values of corresponding asphericity and prolateness factors,with the exception of the chain which shows a minimum value of asphericity when the embedding space has a dimensionality of four.
The shape asymmetry of gaussian models of linear and circular macromolecules hasbeen numerically invesigated in terms of asphericity and prolateness parameters. Theseparameters are found to decrease with increasing length for the macromolecule eitherconfined to a plane or in three dimensions. The effect of dimensionality on theseparameters is visible only for low dimensions and is generally weak. As dimensionality goes to infinity, it is found that asphericity and prolateness for both chains and rings approach slowly yet descendingly values of corresponding asphericity and prolateness factors,with the exception of the chain which shows a minimum value of asphericity when the embedding space has a dimensionality of four.
1995, 13(3): 210-217
Abstract:
Pure X-ray diffraction profiles have been analysed for polyamide 1010 and PA1010--BMI system by means of multipeak fitting resolution of X-ray diffraction.The methods ofvariance and fourth moment have been applied to determine the particle size and strainvalues for theparacrystalline materials.The results indicated that both variance and fourthmoment of X-ray diffraction line profile yielded approximately the same values of theparticle size and the strain.The particle sizes of(100)reflection have been found to decrease with increasing BNI content,whereas the strain values increased.
Pure X-ray diffraction profiles have been analysed for polyamide 1010 and PA1010--BMI system by means of multipeak fitting resolution of X-ray diffraction.The methods ofvariance and fourth moment have been applied to determine the particle size and strainvalues for theparacrystalline materials.The results indicated that both variance and fourthmoment of X-ray diffraction line profile yielded approximately the same values of theparticle size and the strain.The particle sizes of(100)reflection have been found to decrease with increasing BNI content,whereas the strain values increased.
1995, 13(3): 218-227
Abstract:
The effects of inter facial modifier on the mechanical, dynamic mechanical properties andcrystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersedphase of the composites, resulting in different phase structure,which was the major reason leading to different mechanical and crystallization properties.
The effects of inter facial modifier on the mechanical, dynamic mechanical properties andcrystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersedphase of the composites, resulting in different phase structure,which was the major reason leading to different mechanical and crystallization properties.
1995, 13(3): 228-234
Abstract:
We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.
We have shown that some phenylethynylsilicon compounds are good cure crosslinkersof heat-curable silicone rubber(HCSR). In this paper the effects of 1, 1, 3, 3-tetramethyl-1, 3-diphenylethynyldisiloxane (TMDPDS) as a crosslinker on HCSR were studied. Thevulcanizates with fine mechanical properties could be obtained with suitable amounts ofTMDPDS. Sol fractions, and crosslinking density of vulcanizates and vulcanizationretardation effect of TMDPDS on hydrosilation curing silicone rubber were also discussed.
1995, 13(3): 235-243
Abstract:
Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reducethe internal stress owing to the mismatch in coefficient of thermal expansion (CTE).Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to thecuring. In the cured resin, the domain size of the polysiloxane phase depended on thestructure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus ofthe cured resin depended largely on the level of the modifier, while the CTE was affected greatly by the structure of the polysiloxane.By means of incorporating a few percent of methylphenylsiloxane unit into the polydimethylsiloxane chain,or by introducing more compatible end-capping groups,the compounds of more effective low stress modifiers were synthesized.
Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reducethe internal stress owing to the mismatch in coefficient of thermal expansion (CTE).Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to thecuring. In the cured resin, the domain size of the polysiloxane phase depended on thestructure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus ofthe cured resin depended largely on the level of the modifier, while the CTE was affected greatly by the structure of the polysiloxane.By means of incorporating a few percent of methylphenylsiloxane unit into the polydimethylsiloxane chain,or by introducing more compatible end-capping groups,the compounds of more effective low stress modifiers were synthesized.
1995, 13(3): 244-251
Abstract:
An azo-group containing polybutadiene macroinitiator was prepared by Pinner synthesisand characterized by IR, NMR, GPC, viscosity and elemental measurements. Themacroinitiator was further used to polymerize acrylamide (AAm) in benzene to formpolybutadiene/polyacrylamide (PBD/PAAm) block copolymers. High conversion of AAm wasobtained over a wide range of monomer/macroinitiator ratios. The PBD/PAAm blockcopolymers.were found to have excellent solvent resistance.
An azo-group containing polybutadiene macroinitiator was prepared by Pinner synthesisand characterized by IR, NMR, GPC, viscosity and elemental measurements. Themacroinitiator was further used to polymerize acrylamide (AAm) in benzene to formpolybutadiene/polyacrylamide (PBD/PAAm) block copolymers. High conversion of AAm wasobtained over a wide range of monomer/macroinitiator ratios. The PBD/PAAm blockcopolymers.were found to have excellent solvent resistance.
1995, 13(3): 252-258
Abstract:
Experiments including 13C spin-lattice relaxation,13C heteronuclear dipolar dephasing and1H spin diffusion are performed on poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO). Theresults show that the rotation of the methyl groups in solid PPO is partially restricted, whichresults in a surprisingly efficient spin diffusion between the aromatic proton and methyl protoncharacterized by a diffusion time of 150μs. The results also show that the aromatic ring insolid PPO is rigid and twisted, which causes all aromatic carbons to be chemically unequivalent.
Experiments including 13C spin-lattice relaxation,13C heteronuclear dipolar dephasing and1H spin diffusion are performed on poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO). Theresults show that the rotation of the methyl groups in solid PPO is partially restricted, whichresults in a surprisingly efficient spin diffusion between the aromatic proton and methyl protoncharacterized by a diffusion time of 150μs. The results also show that the aromatic ring insolid PPO is rigid and twisted, which causes all aromatic carbons to be chemically unequivalent.
1995, 13(3): 259-263
Abstract:
Photoinduced charge transfer polymerization of styrene (St) with electron acceptor asinitiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) asinitiator the polymerization takes place regularly, whereas the tetrachloro-1, 4-benzenequinone (TCQ), 2, 3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). ortetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only afterthe photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron acceptors.
Photoinduced charge transfer polymerization of styrene (St) with electron acceptor asinitiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) asinitiator the polymerization takes place regularly, whereas the tetrachloro-1, 4-benzenequinone (TCQ), 2, 3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). ortetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only afterthe photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron acceptors.
1995, 13(3): 264-272
Abstract:
A new comblike polymer host for polymer electrolyte was synthesized by reactingmonomethyl ether of poly (ethylene glycol) with poly (vinyl methyl ether alt-maleic anhydride)and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solventfor the esterification in order to obtain a completely soluble product. The synthesis processwas traced through by IR. Compared with the model compounds, the presumed structure ofthis comblike polymer has been proved to be valid by 13C NMR. The comb polymer is a white rubbery solid.It can be dissolved in butanone and THF,and manifests good film forming ability.
A new comblike polymer host for polymer electrolyte was synthesized by reactingmonomethyl ether of poly (ethylene glycol) with poly (vinyl methyl ether alt-maleic anhydride)and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solventfor the esterification in order to obtain a completely soluble product. The synthesis processwas traced through by IR. Compared with the model compounds, the presumed structure ofthis comblike polymer has been proved to be valid by 13C NMR. The comb polymer is a white rubbery solid.It can be dissolved in butanone and THF,and manifests good film forming ability.
1995, 13(3): 273-279
Abstract:
A new reactive graft copolymer, poly (dimethyl siloxane )-graft-ω-hydroxyl-poly(ethylene oxide) (PDMS-g-(PEO--OH)), was synthesized by the hydrosilylation reactionof α, ω-bifunctional PEO macromonomer (CH2=CH--CH2--PEO--OH) with poly(hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comb-like structure as indicated by the result of detailed characterization and the neededreactivity as demonstrated by the result of esterification between PDMS-g-(PEO--OH)and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer meterials.
A new reactive graft copolymer, poly (dimethyl siloxane )-graft-ω-hydroxyl-poly(ethylene oxide) (PDMS-g-(PEO--OH)), was synthesized by the hydrosilylation reactionof α, ω-bifunctional PEO macromonomer (CH2=CH--CH2--PEO--OH) with poly(hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comb-like structure as indicated by the result of detailed characterization and the neededreactivity as demonstrated by the result of esterification between PDMS-g-(PEO--OH)and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer meterials.
1995, 13(3): 280-284
Abstract:
The thermotropic liquid crystalline behavior of a fusible polydiacetylene has beenstudied by using polarizing optical microscopy and wide angle X-ray diffraction. It wasfound that the typical threaded texture can exhibit in the melt and the banded texture canbe observed when applied a gentle shear to the melt. The results indicate that thispolydiacetylene is really a thermotropic liquid crystalline polymer.
The thermotropic liquid crystalline behavior of a fusible polydiacetylene has beenstudied by using polarizing optical microscopy and wide angle X-ray diffraction. It wasfound that the typical threaded texture can exhibit in the melt and the banded texture canbe observed when applied a gentle shear to the melt. The results indicate that thispolydiacetylene is really a thermotropic liquid crystalline polymer.
1995, 13(3): 285-288
Abstract:
A series of novel mesogenic polyesters with 2-dich1oromethylhydroquinone moieties weresynthesized by polycondensation of the novel diacyl chloride monomer 2-dichloromethyl-1, 4-bis (4'-chloroformylbenzoyl) oxybenzene-(I) with α,ω-polymethylenediols including ethyleneglycol, 1, 4-butanediol, 1, 6-hexanediol and 1, 10-decanediol. The diacyl chloride monomerwas synthesized by simultaneous transformations of both the carboxy and formaldehydegroups of 2-formyl-1, 4-bis (4'-carboxybenzoyl) oxybenzene into acyl choride and dichloromethyl groups respectively.The syntheses of the monomer (I) and the polymers were reported.
A series of novel mesogenic polyesters with 2-dich1oromethylhydroquinone moieties weresynthesized by polycondensation of the novel diacyl chloride monomer 2-dichloromethyl-1, 4-bis (4'-chloroformylbenzoyl) oxybenzene-(I) with α,ω-polymethylenediols including ethyleneglycol, 1, 4-butanediol, 1, 6-hexanediol and 1, 10-decanediol. The diacyl chloride monomerwas synthesized by simultaneous transformations of both the carboxy and formaldehydegroups of 2-formyl-1, 4-bis (4'-carboxybenzoyl) oxybenzene into acyl choride and dichloromethyl groups respectively.The syntheses of the monomer (I) and the polymers were reported.
