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1994 Volume 12 Issue 2
1994, 12(2): 97-105
Abstract:
The electric conductivity, dynamic modulus and yield stress of the developed electrorheolo-gical fluid (ERF) are measured at different volume fraction and different electric field strengthusing a modified Rheometrics Mechanical Spectrometer (Model 605). The percolation theory isintroduced to explain electrorheological effect and found that the ERF′s have the similarpercolated network structure as that of other ordinary suspensions with a critical volume fractionvalue independent of electric field strength. A master curve of dimensionless modulus against dimensionless volume fraction is abtained,which shows that the essence of ER phenomenon actually is one kind of the second ofder phase transition.
The electric conductivity, dynamic modulus and yield stress of the developed electrorheolo-gical fluid (ERF) are measured at different volume fraction and different electric field strengthusing a modified Rheometrics Mechanical Spectrometer (Model 605). The percolation theory isintroduced to explain electrorheological effect and found that the ERF′s have the similarpercolated network structure as that of other ordinary suspensions with a critical volume fractionvalue independent of electric field strength. A master curve of dimensionless modulus against dimensionless volume fraction is abtained,which shows that the essence of ER phenomenon actually is one kind of the second ofder phase transition.
1994, 12(2): 106-113
Abstract:
With the help of differential scanning calorimetry, cone-plate and capillary rheometry andscanning electron microscopy, a research has been conducted on rheological behavior,crystallization and morphology of poly (butylene terephthalate) (PBT) blends containing athermotropic LCP. The blend has zero entrance pressure loss, although the LCP has rather largeone. The viscosity curve of the blend lies between those of the LCP and PBT. The crystallizationof PBT is not affected by the presence of the LCP together with no indication of transesterification between the two ingredients.LCP spheres and ellipsoids with the size of 0.5-1.5μm disperse in PBT matrix uniformly,which is related to the viscosity ratio of the two components.
With the help of differential scanning calorimetry, cone-plate and capillary rheometry andscanning electron microscopy, a research has been conducted on rheological behavior,crystallization and morphology of poly (butylene terephthalate) (PBT) blends containing athermotropic LCP. The blend has zero entrance pressure loss, although the LCP has rather largeone. The viscosity curve of the blend lies between those of the LCP and PBT. The crystallizationof PBT is not affected by the presence of the LCP together with no indication of transesterification between the two ingredients.LCP spheres and ellipsoids with the size of 0.5-1.5μm disperse in PBT matrix uniformly,which is related to the viscosity ratio of the two components.
1994, 12(2): 114-121
Abstract:
The calculating equations which could be used to obtain diad composition from the peakintensities of carbon spectra were derived. The result of the microstructure calculated from thediad compositions was in good agreement with that obtained through IR or 1H-NMR measurement.
The calculating equations which could be used to obtain diad composition from the peakintensities of carbon spectra were derived. The result of the microstructure calculated from thediad compositions was in good agreement with that obtained through IR or 1H-NMR measurement.
1994, 12(2): 122-125
Abstract:
Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF2) during quenching process.For pure PVF2, quenching at lower temperature results in the formation of β phase crystallites.The critical quenching temperature for β phase formation is about 30℃. Adding a given amountof PMMA (30%) results in the increase of the critical quenching temperature. For the blends ofPVF2 with atactic PMMA (a-PMMA), the critical quenching temperature is about 45℃,while for the blends with syndiotactic PMMA (s-PMMA),attains to about 70℃.
Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF2) during quenching process.For pure PVF2, quenching at lower temperature results in the formation of β phase crystallites.The critical quenching temperature for β phase formation is about 30℃. Adding a given amountof PMMA (30%) results in the increase of the critical quenching temperature. For the blends ofPVF2 with atactic PMMA (a-PMMA), the critical quenching temperature is about 45℃,while for the blends with syndiotactic PMMA (s-PMMA),attains to about 70℃.
1994, 12(2): 126-131
Abstract:
In this paper, the microstructure change of one step-draw PET fiber has been studied byvarious methods, such as, Laser Raman Microscope, Wide-angle X-ray, Density-gradient andPolarizing Microscope. The computer has been used to resolve overlapped bands in the Ramanspectra. Then the band changes have been correlated with trans, gauche and stressed trans-conformations indicated by a conformational index. Based on these indices, the relationshipbetween the conformation change of glycol units in the fiber structure and the macromechanical properties of fiber is expounded.
In this paper, the microstructure change of one step-draw PET fiber has been studied byvarious methods, such as, Laser Raman Microscope, Wide-angle X-ray, Density-gradient andPolarizing Microscope. The computer has been used to resolve overlapped bands in the Ramanspectra. Then the band changes have been correlated with trans, gauche and stressed trans-conformations indicated by a conformational index. Based on these indices, the relationshipbetween the conformation change of glycol units in the fiber structure and the macromechanical properties of fiber is expounded.
1994, 12(2): 132-136
Abstract:
The effects of chemical structure, i. e. side chain structure and their contents, on thepermeability of pure SO2, N2 and their mixture gases for the sulfoxide grafted poly (vinylalcohol) (RVSO-PVA) membranes have been investigated:where R=Me, Et, Pr, t-Bu and Ph. It was notable that introduction of sulfoxide group intoPVA side chain greatly enhanced the permselectivity of sulfur dioxide. SO2 permeability andseparation factor of these polymers increased markedly as the size of side chain increased. The sulfoxide content of the polymer also played an important role in the pure and mixture gases permeation.Some explanations have been made to interpret this unique gas separation behaviour.
The effects of chemical structure, i. e. side chain structure and their contents, on thepermeability of pure SO2, N2 and their mixture gases for the sulfoxide grafted poly (vinylalcohol) (RVSO-PVA) membranes have been investigated:where R=Me, Et, Pr, t-Bu and Ph. It was notable that introduction of sulfoxide group intoPVA side chain greatly enhanced the permselectivity of sulfur dioxide. SO2 permeability andseparation factor of these polymers increased markedly as the size of side chain increased. The sulfoxide content of the polymer also played an important role in the pure and mixture gases permeation.Some explanations have been made to interpret this unique gas separation behaviour.
1994, 12(2): 137-144
Abstract:
Two copolymers containing p-tolylcarbamoyl pendant group poly (MAMT-co-VAc) and poly(MAMT-co-MA) were synthesized f and the graft copolymerization of AAM onto these two func-tional copolymers films initiated with ceric salt were carried out in aqueous solution for variousperiods at 30℃. The formation of graft copolymer was verified by water absorption, ESCA andSEM photographs. Based on the results of the study of the initiation mechanism of model com-pounds and ceric salt systems, the reaction mechanism of graft copolymerization initiated with ceric salt was proposed.
Two copolymers containing p-tolylcarbamoyl pendant group poly (MAMT-co-VAc) and poly(MAMT-co-MA) were synthesized f and the graft copolymerization of AAM onto these two func-tional copolymers films initiated with ceric salt were carried out in aqueous solution for variousperiods at 30℃. The formation of graft copolymer was verified by water absorption, ESCA andSEM photographs. Based on the results of the study of the initiation mechanism of model com-pounds and ceric salt systems, the reaction mechanism of graft copolymerization initiated with ceric salt was proposed.
1994, 12(2): 145-152
Abstract:
The synthesis and phase behaviour of chiral combined main/side chain liquid crystallinecopolymers containing pendant group constituted by chiral side group and trans-azobenzenemoiety with nitro end group are described. The formation of liquid crystalline polymorphism ofcopolymers is influenced by various contents of achiral side group.
The synthesis and phase behaviour of chiral combined main/side chain liquid crystallinecopolymers containing pendant group constituted by chiral side group and trans-azobenzenemoiety with nitro end group are described. The formation of liquid crystalline polymorphism ofcopolymers is influenced by various contents of achiral side group.
1994, 12(2): 153-156
Abstract:
Epichlorohydrin (ECH) was polymerized with a rare earth catalytic system: Nd (i-OPr)3-Al (i-Bu)3. The effects of Al/Nd molar ratio, solvents, the polymerization time and temperature,the aging time and temperature of the catalyst preparation were studied. The results showed thatat a low Al/Nd molar ratio (4) of the Nd(i-OPr)3-Al(i-Bu)3 system ECH polymerized at a lowtemperature (248K) with a high conversion. The average molecular weight ofpolyepichlorohydrin (PECH) ranged from 1×105 to 3×105.
Epichlorohydrin (ECH) was polymerized with a rare earth catalytic system: Nd (i-OPr)3-Al (i-Bu)3. The effects of Al/Nd molar ratio, solvents, the polymerization time and temperature,the aging time and temperature of the catalyst preparation were studied. The results showed thatat a low Al/Nd molar ratio (4) of the Nd(i-OPr)3-Al(i-Bu)3 system ECH polymerized at a lowtemperature (248K) with a high conversion. The average molecular weight ofpolyepichlorohydrin (PECH) ranged from 1×105 to 3×105.
1994, 12(2): 157-163
Abstract:
Metal foils for Raman scattering were prepared by HNO3 etching method. These foils werefound to exhibit a strong SERS effect and excellent thermal stability. SERS spectra of cystaminehave been taken to illustrate the usefulness of this sample preparation method in the studies ofchemisorption. The ring opening reactions of an epoxy compound have been observed on the topof chemisorbed cystamine on silver foils.
Metal foils for Raman scattering were prepared by HNO3 etching method. These foils werefound to exhibit a strong SERS effect and excellent thermal stability. SERS spectra of cystaminehave been taken to illustrate the usefulness of this sample preparation method in the studies ofchemisorption. The ring opening reactions of an epoxy compound have been observed on the topof chemisorbed cystamine on silver foils.
1994, 12(2): 164-172
Abstract:
In the present work, the structure and impact properties of copolymers of polypropylenewith low ethylene contents have been investigated. Based on the results of 13C--NMR, FTIR,WAXD, DSC, PLM and SEM, the relationship between impact properties and morphology of thecopolymers has been discussed. The high impact properties of copolymer ICP2 may attribute tothe relatively higher ethylene content and homogeneous ethylene unit distribution. The size andits distribution of spherulite in the copolymers and cycloid cavitites dispersed in polypropylene continue phase may also be two important factors which affect the impact properties of these materials.
In the present work, the structure and impact properties of copolymers of polypropylenewith low ethylene contents have been investigated. Based on the results of 13C--NMR, FTIR,WAXD, DSC, PLM and SEM, the relationship between impact properties and morphology of thecopolymers has been discussed. The high impact properties of copolymer ICP2 may attribute tothe relatively higher ethylene content and homogeneous ethylene unit distribution. The size andits distribution of spherulite in the copolymers and cycloid cavitites dispersed in polypropylene continue phase may also be two important factors which affect the impact properties of these materials.
1994, 12(2): 173-179
Abstract:
The lamellar structure of a thermotropic aromatic polyester with flexible spacer has beenstudied by using transmission electron microscopy. It was found that the lamellar structure couldbe observed in the crystalline samples of this semirigid polymer crystallized from different states.The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymersof flexible chain molecules. The molecular chains in the lamellae are oriented in the thicknessdirection as determined by electron diffraction.The possibility of molecular chains folding in the lamellae has been discussed.
The lamellar structure of a thermotropic aromatic polyester with flexible spacer has beenstudied by using transmission electron microscopy. It was found that the lamellar structure couldbe observed in the crystalline samples of this semirigid polymer crystallized from different states.The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymersof flexible chain molecules. The molecular chains in the lamellae are oriented in the thicknessdirection as determined by electron diffraction.The possibility of molecular chains folding in the lamellae has been discussed.
1994, 12(2): 180-184
Abstract:
Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C1s spectra and some newbands, e. g. at 1220 and 580cm-1 in IR spectra were formed.The fact,Po2 permeability of oxygen,decreased and αo2/N2,separation factor of oxygen relative to nitrogen,increased with bromination time,shows that surface modification of PTMSP by bromine may be an effcient approach to prepare PTMSP membranes used for practical gas separations.
Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C1s spectra and some newbands, e. g. at 1220 and 580cm-1 in IR spectra were formed.The fact,Po2 permeability of oxygen,decreased and αo2/N2,separation factor of oxygen relative to nitrogen,increased with bromination time,shows that surface modification of PTMSP by bromine may be an effcient approach to prepare PTMSP membranes used for practical gas separations.
1994, 12(2): 185-189
Abstract:
Poly(styrene-co-4-vinylpyridine)-neodymium complexes(NdCl3·PS4VPY)with variouscontents of the functional group and neodymium have been prepared and characterized.Theinfrared and X-ray photoelectron spectra indicate that uncoordinated 4-vinylpyridine(4VPY)unitsremain in the NdCl3·PS4VPY complexes.The catalytic behaviour of NdCl3·PS4VPY was described briefly.
Poly(styrene-co-4-vinylpyridine)-neodymium complexes(NdCl3·PS4VPY)with variouscontents of the functional group and neodymium have been prepared and characterized.Theinfrared and X-ray photoelectron spectra indicate that uncoordinated 4-vinylpyridine(4VPY)unitsremain in the NdCl3·PS4VPY complexes.The catalytic behaviour of NdCl3·PS4VPY was described briefly.
1994, 12(2): 190-192
Abstract:
The copolymerization process of triphenylmethyl methacrylate (TrMA) and methylmethacrylate (MMA) using chiral anionic complex initiator (-) SP-FlLi (Scheme 1) has beenstudied in toluene and THF, respectively. The copolymer obtained in toluene possessed muchhigher specific rotation than that in THF. These copolymers have shown a tendency to a random and a like alternating structure, respectively.
The copolymerization process of triphenylmethyl methacrylate (TrMA) and methylmethacrylate (MMA) using chiral anionic complex initiator (-) SP-FlLi (Scheme 1) has beenstudied in toluene and THF, respectively. The copolymer obtained in toluene possessed muchhigher specific rotation than that in THF. These copolymers have shown a tendency to a random and a like alternating structure, respectively.
