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1999 Volume 17 Issue 3
1999, 17(3): 203-213
Abstract:
The shape memory effect of polymers was investigated for the purpose of improving the processingconditions of their preparation and broadening the list of polymers for shape memory applications. Emphasiswas put on the possibility of using polymers with physical crosslinks as shape memory materials and theirstructure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymerswere used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoberable strain and high final recovery rate.The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks.As only physical crosslinks are introduced,all conventional processing techniques for thermal plastics can be used,and the materials become easily reusable.The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect.The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.
The shape memory effect of polymers was investigated for the purpose of improving the processingconditions of their preparation and broadening the list of polymers for shape memory applications. Emphasiswas put on the possibility of using polymers with physical crosslinks as shape memory materials and theirstructure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymerswere used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoberable strain and high final recovery rate.The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks.As only physical crosslinks are introduced,all conventional processing techniques for thermal plastics can be used,and the materials become easily reusable.The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect.The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.
1999, 17(3): 215-220
Abstract:
PMMA films in the high global chain orientation and nearly random segmental orientation(GOLR) state were prepared by uni-axially drawing at temperatures 20～30℃ above its glass transitiontempefature, T_g, and their isotropic and anisotropic properties were studied. Experimental results show thatthis kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism andX-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling and stress-strain.
PMMA films in the high global chain orientation and nearly random segmental orientation(GOLR) state were prepared by uni-axially drawing at temperatures 20～30℃ above its glass transitiontempefature, T_g, and their isotropic and anisotropic properties were studied. Experimental results show thatthis kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism andX-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling and stress-strain.
1999, 17(3): 221-229
Abstract:
The hydrophilicity, dyeing and antistatic ability of polypropylene microfibre (PPMF) wereimproved by plasma-induced vapor grafting with acrylic acid. The effects of plasma discharge time, power,liquid phase acrylic acid temperature and environmental temperatore on grafting yield were investigated. Theexistence of grafted polyacrylic acid (PAA) was verified by ESCA and ATR FT-IR. The morphology ofgrafted PAA was directly observed by SEM. The wicking test shows that the hydrophilicity of modified PPMF is greatly enhanced.The dyeability test of modified PPMF was carried out using Dispersion Yellow.It was found that the dye uptake ratio is linear to the weight percent of grafting.The antistatic ability was indicated by specific resistance.The specific resistance of modified PPMF was reduced to 106～107Ω·cm,thus the antistatic ability was considerably improved.
The hydrophilicity, dyeing and antistatic ability of polypropylene microfibre (PPMF) wereimproved by plasma-induced vapor grafting with acrylic acid. The effects of plasma discharge time, power,liquid phase acrylic acid temperature and environmental temperatore on grafting yield were investigated. Theexistence of grafted polyacrylic acid (PAA) was verified by ESCA and ATR FT-IR. The morphology ofgrafted PAA was directly observed by SEM. The wicking test shows that the hydrophilicity of modified PPMF is greatly enhanced.The dyeability test of modified PPMF was carried out using Dispersion Yellow.It was found that the dye uptake ratio is linear to the weight percent of grafting.The antistatic ability was indicated by specific resistance.The specific resistance of modified PPMF was reduced to 106～107Ω·cm,thus the antistatic ability was considerably improved.
1999, 17(3): 231-235
Abstract:
Poly(ethylene terephthalate) -polycaprolactone block copolymer (PCL- b-PET) is a polyester withimproved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)4 was proposed for thesynthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and 1H-NMRtechniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.
Poly(ethylene terephthalate) -polycaprolactone block copolymer (PCL- b-PET) is a polyester withimproved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)4 was proposed for thesynthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and 1H-NMRtechniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.
1999, 17(3): 237-244
Abstract:
The interface behavior of polyamide 1010 (PA1010) and polypropylene (PP) was studied. In orderto improve their interfacial adhesion, functional PP was prepared by means of grafting glycidyl methacrylate(GMA) on PP main chains and used instead of plain PP. Several technological characterizations wereperformed here on their interfaces. ESCA was used to confirm that some kind of reaction occurred betweenend groups of PA1010 and epoxy species of PP-g-GMA. The peel test was adopted to measure interfacial adhesion.It was found that the fracture energy of interfaces between PA1010 and PP-g-GMA was dramatically increased with the content of GMA.Their interfaces were obserevd as being blurred by using SEM and TEM and a crack that could be seen in the case of the interfaces of the PA1010 and the plain PP disappeared.
The interface behavior of polyamide 1010 (PA1010) and polypropylene (PP) was studied. In orderto improve their interfacial adhesion, functional PP was prepared by means of grafting glycidyl methacrylate(GMA) on PP main chains and used instead of plain PP. Several technological characterizations wereperformed here on their interfaces. ESCA was used to confirm that some kind of reaction occurred betweenend groups of PA1010 and epoxy species of PP-g-GMA. The peel test was adopted to measure interfacial adhesion.It was found that the fracture energy of interfaces between PA1010 and PP-g-GMA was dramatically increased with the content of GMA.Their interfaces were obserevd as being blurred by using SEM and TEM and a crack that could be seen in the case of the interfaces of the PA1010 and the plain PP disappeared.
1999, 17(3): 245-251
Abstract:
A new spherulite-like structure of main chain thermotropic aromatic copolyesters formed insolution cast specimens was observed and was studied by means of polarizing microscopy, X-ray diffraction,SEM and IR spectrometry. Results indicate that the spherulite-like structure of main chain thermotropicaromatic copolyesters formed from the casting solution (phenol/Cl2CH2CH2Cl2) is not a real crystal but only ahigh oriented arrangement of the macromolecular chains as a spherulite. This resulted from the interaction between the needle-like crystal of phenol and the rigid mesomorphic groups of molecular chain.The parallel packuing of extended copolyester molecules along the needle-like crystal of phenol leads to the formation of the spherulite-like structure.
A new spherulite-like structure of main chain thermotropic aromatic copolyesters formed insolution cast specimens was observed and was studied by means of polarizing microscopy, X-ray diffraction,SEM and IR spectrometry. Results indicate that the spherulite-like structure of main chain thermotropicaromatic copolyesters formed from the casting solution (phenol/Cl2CH2CH2Cl2) is not a real crystal but only ahigh oriented arrangement of the macromolecular chains as a spherulite. This resulted from the interaction between the needle-like crystal of phenol and the rigid mesomorphic groups of molecular chain.The parallel packuing of extended copolyester molecules along the needle-like crystal of phenol leads to the formation of the spherulite-like structure.
1999, 17(3): 253-257
Abstract:
Nano silica-modified epoxy resins were synthesized by the sol-gel process. The materials have themorphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed aphysical network in the resin and thus influenced the rheological behavior greatly. However, the nano silicadid not show a significant influence on the mechanical properties of the cured resins.
Nano silica-modified epoxy resins were synthesized by the sol-gel process. The materials have themorphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed aphysical network in the resin and thus influenced the rheological behavior greatly. However, the nano silicadid not show a significant influence on the mechanical properties of the cured resins.
1999, 17(3): 259-264
Abstract:
Poly(ethylene methyl phosphate)-poly(ethylene glycol)-poly(ethylene methyl phosphate) triblockcopolymers carrying hydroxyl group at both chain ends were synthesized with sodium poly(ethyleneglycol)ate as initiator. The effects of the factors such as solvent, amount of the initiator and reaction timewere investigated. The copolymers were characterized by IR,1H-NMR, 1H{31P}-NMR, 13C-NMR, 31P{1H}-NMR, and DSC. High molecular weight of the copolymer and high yield of the polymerization were achieved within 3 min at 25℃.The polymerization process was studied by 31P{1H}-NMR and transesterification was found during longer polymerization time.
Poly(ethylene methyl phosphate)-poly(ethylene glycol)-poly(ethylene methyl phosphate) triblockcopolymers carrying hydroxyl group at both chain ends were synthesized with sodium poly(ethyleneglycol)ate as initiator. The effects of the factors such as solvent, amount of the initiator and reaction timewere investigated. The copolymers were characterized by IR,1H-NMR, 1H{31P}-NMR, 13C-NMR, 31P{1H}-NMR, and DSC. High molecular weight of the copolymer and high yield of the polymerization were achieved within 3 min at 25℃.The polymerization process was studied by 31P{1H}-NMR and transesterification was found during longer polymerization time.
1999, 17(3): 265-270
Abstract:
Poly-dl -lactide-poly(ethylene glycol ) (PELA) triblock copolymers were synthesized withlanthanum acetate as the initiator. PELA microspheres with entrapped Vibrio Cholera antigen and outermembrane protein (OMP) were prepared by a double emulsion W/O/W based on solvent extraction methods.The obtained microspheres showed smooth and spherical surface and their size varied between 0.5 and 5.0μm, which are suitable for oral targeting delivery system. The distribution tests in rabbits and mice through scanning electronic micrography and fluorescence microscope indicated that microspheres have successfully reached the immunization-related tissues,such as the liver,spleen and intestinal peyer's patches,following oral administration.The PELA microspheres were also evaluated as an efficient antigen delivery system by enhancing a higher protective ratio against live Vibrios Cholera.
Poly-dl -lactide-poly(ethylene glycol ) (PELA) triblock copolymers were synthesized withlanthanum acetate as the initiator. PELA microspheres with entrapped Vibrio Cholera antigen and outermembrane protein (OMP) were prepared by a double emulsion W/O/W based on solvent extraction methods.The obtained microspheres showed smooth and spherical surface and their size varied between 0.5 and 5.0μm, which are suitable for oral targeting delivery system. The distribution tests in rabbits and mice through scanning electronic micrography and fluorescence microscope indicated that microspheres have successfully reached the immunization-related tissues,such as the liver,spleen and intestinal peyer's patches,following oral administration.The PELA microspheres were also evaluated as an efficient antigen delivery system by enhancing a higher protective ratio against live Vibrios Cholera.
1999, 17(3): 271-280
Abstract:
A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with differentsoft segment length and hard segment content were synthesized. The compositional heterogeneity was studiedby solvent extraction. The results show that the compositional heterogeneity increases when soft segmentlength and hard segment content increase. The compositional heterogeneity is also reflected in thecrystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more composition behavior and morphology of soft and hard segment in EOBT segmented copolymer.The more compositional heterogeneous the EOBT segmented copolymer is,the more different the morphology and the crystallization behavior between separated fractions.Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer,compositional heterogeneity in EOBT segmented copolymer is weaker.But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.
A series of ethylene oxide-butylene terephthalate (EOBT) segmented copolymers with differentsoft segment length and hard segment content were synthesized. The compositional heterogeneity was studiedby solvent extraction. The results show that the compositional heterogeneity increases when soft segmentlength and hard segment content increase. The compositional heterogeneity is also reflected in thecrystallization behavior and morphology of soft and hard segment in EOBT segmented copolymer. The more composition behavior and morphology of soft and hard segment in EOBT segmented copolymer.The more compositional heterogeneous the EOBT segmented copolymer is,the more different the morphology and the crystallization behavior between separated fractions.Compared with ethylene oxide-ethylene terephthalate (EOET) segmented copolymer,compositional heterogeneity in EOBT segmented copolymer is weaker.But the compositional heterogeneity in EOBT segmented copolymer with long soft segment and high hard segment content is still obvious.
1999, 17(3): 281-288
Abstract:
In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer withacrylamide is reported. 2 -perfluoroamyl -4- hydroxylquinoline 2 was synthesized from ethyl 2, 2 -dihydro-perfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in highyields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer wereinvestigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles,pseudoplasticity of these solutions and the effect of the presence of surfactant.These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.
In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer withacrylamide is reported. 2 -perfluoroamyl -4- hydroxylquinoline 2 was synthesized from ethyl 2, 2 -dihydro-perfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in highyields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer wereinvestigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles,pseudoplasticity of these solutions and the effect of the presence of surfactant.These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.
1999, 17(3): 289-294
Abstract:
A new liquid crystalline polyacetylene containing a phenyl benzoate mesogen (5) is synthesized,whose mesomorphic properties are found to be easily "tunab1e" by simple mechanical perturbation. Thepolymerization of 10- [ 4 - (4' -methoxyphenoxycarbonyl )phenoxycarbonyl] - 1 -decyne (4 ) in itiated by theWCl6-Ph4Sn/dioxane complex yields polymer 5 with a Mw of 28400. The molecular structure of 5 is characterized by NMR, IR, and UV spectroscopy and its liquid crystalline behavior is investigated by DSC,POM, and XRD analysis.Upon mechanical perturbation,5 exhibits unusual agitation-induced high-strength disclinations,shear-induced inversion walls,and solidification-induced banded textures.Such phenomena have been observed in the main-chain liquid crystalline polymers with rigid backbones,but have seldom been reported for the side-chain liquid crystalline polymers with flexible backbones,suggesting that the rigid polyacetylene backbone of 5 plays a constructive role in inducing the novel molecular alignments.
A new liquid crystalline polyacetylene containing a phenyl benzoate mesogen (5) is synthesized,whose mesomorphic properties are found to be easily "tunab1e" by simple mechanical perturbation. Thepolymerization of 10- [ 4 - (4' -methoxyphenoxycarbonyl )phenoxycarbonyl] - 1 -decyne (4 ) in itiated by theWCl6-Ph4Sn/dioxane complex yields polymer 5 with a Mw of 28400. The molecular structure of 5 is characterized by NMR, IR, and UV spectroscopy and its liquid crystalline behavior is investigated by DSC,POM, and XRD analysis.Upon mechanical perturbation,5 exhibits unusual agitation-induced high-strength disclinations,shear-induced inversion walls,and solidification-induced banded textures.Such phenomena have been observed in the main-chain liquid crystalline polymers with rigid backbones,but have seldom been reported for the side-chain liquid crystalline polymers with flexible backbones,suggesting that the rigid polyacetylene backbone of 5 plays a constructive role in inducing the novel molecular alignments.
1999, 17(3): 295-298
Abstract:
A novel methacrylate monomer with bulky side group, tri(2-pyridyl)methyl methacrylate(Tr2PyMA), was synthesized and polymerized. The polymer obtained by radical polymerization exhibits highisotactic tacticity.
A novel methacrylate monomer with bulky side group, tri(2-pyridyl)methyl methacrylate(Tr2PyMA), was synthesized and polymerized. The polymer obtained by radical polymerization exhibits highisotactic tacticity.
1999, 17(3): 299-302
Abstract:
In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymerswere prepared by copolymerization for preparing membrane materials. The composite membrane of celluloseacetate (CA) blended with MMA-AA hydrophobic copolymer was used for the separation of methanol frompentane-methanol mixture. When the methanol concentration was only 1 wt% ,the permeate flux stillmaintained at 350 g/m2h and separation factor was as big as 800. The composite membrane of PVA(polyvinyl alcohol) blended with MMA-AA hydrophilic copolymer was used for the separation of ethanol-water mixture.The permeate flux was increased to 975g/m2h at 74℃ and the separation factor reached 3000 at 25℃.The PVA/MMA-AA blended membrane surface modified by ammonia plasma was also investigated for separating ethanol-water mixture.Both permeate flux and separation factor of the membrane was improved.However,there was on obvious difference of plasma treatment time in the interval of 20～40 min.
In this paper, methylmethacrylate-acrylic acid MMA-AA hydrophilic and hydrophobic copolymerswere prepared by copolymerization for preparing membrane materials. The composite membrane of celluloseacetate (CA) blended with MMA-AA hydrophobic copolymer was used for the separation of methanol frompentane-methanol mixture. When the methanol concentration was only 1 wt% ,the permeate flux stillmaintained at 350 g/m2h and separation factor was as big as 800. The composite membrane of PVA(polyvinyl alcohol) blended with MMA-AA hydrophilic copolymer was used for the separation of ethanol-water mixture.The permeate flux was increased to 975g/m2h at 74℃ and the separation factor reached 3000 at 25℃.The PVA/MMA-AA blended membrane surface modified by ammonia plasma was also investigated for separating ethanol-water mixture.Both permeate flux and separation factor of the membrane was improved.However,there was on obvious difference of plasma treatment time in the interval of 20～40 min.
