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2006 Volume 24 Issue 1
2006, 24(1): 1-11
Abstract:
Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions. The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.
Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions. The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.
2006, 24(1): 13-19
Abstract:
It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p(r) of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p(r) of short two-dimensional compact polymers chains may consist of two parts, i.e. p(r) = p1(r) + p2(r), where p1(r) and p2(r) are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k(N) N. Here the value of increases with the contact radius a and it also depends on the percentage of H (hydrophobic) residues in the sequences of compact chains and the energy parameters of , and . Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.
It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p(r) of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p(r) of short two-dimensional compact polymers chains may consist of two parts, i.e. p(r) = p1(r) + p2(r), where p1(r) and p2(r) are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k(N) N. Here the value of increases with the contact radius a and it also depends on the percentage of H (hydrophobic) residues in the sequences of compact chains and the energy parameters of , and . Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.
2006, 24(1): 21-27
Abstract:
By treating disodium(thiophenedimethylene)dicyclopentadienide C4H2S(CH2C5H4Na)2 with two equivalent of CpTiCl3 or CpZrCl3•DME at 0℃ in THF, two new thiophenedimethylene bridged binuclear metallocenes [Cl2MC5H5][C5H4CH2C4H2SCH2C5H4][C5H5MCl2] (M = Ti 3, M = Zr 4) were synthesized in high yield and their structures were characterized by 1H-NMR. These complexes were used as catalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). The effects of polymerization temperature, time, concentration of catalyst, molar ratio of MAO/Cat on polymerization were studied in detail. The catalytic activities of thiophenedimethylene bridged binuclear metallocene catalysts (3, 4) reached 2.44 105 g PE mol1•cat1•h1, 9.61 105 g PE mol1•cat1•h1 respectively, which are higher than that of pheneyldimethylene bridged binuclear metallocene catalysts and much higher than that of corresponding mononuclear metallocenes (Cp2TiCl2 and Cp2ZrCl2). The molecular weight distribution curves of polyethylenes produced by binuclear metallocene catalysts (3, 4) and by mononuclear metallocene catalyst have only single peak, but the former (MWD = 3.54.7) is obviously broader than the latter (MWD = 2.02.2).
By treating disodium(thiophenedimethylene)dicyclopentadienide C4H2S(CH2C5H4Na)2 with two equivalent of CpTiCl3 or CpZrCl3•DME at 0℃ in THF, two new thiophenedimethylene bridged binuclear metallocenes [Cl2MC5H5][C5H4CH2C4H2SCH2C5H4][C5H5MCl2] (M = Ti 3, M = Zr 4) were synthesized in high yield and their structures were characterized by 1H-NMR. These complexes were used as catalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). The effects of polymerization temperature, time, concentration of catalyst, molar ratio of MAO/Cat on polymerization were studied in detail. The catalytic activities of thiophenedimethylene bridged binuclear metallocene catalysts (3, 4) reached 2.44 105 g PE mol1•cat1•h1, 9.61 105 g PE mol1•cat1•h1 respectively, which are higher than that of pheneyldimethylene bridged binuclear metallocene catalysts and much higher than that of corresponding mononuclear metallocenes (Cp2TiCl2 and Cp2ZrCl2). The molecular weight distribution curves of polyethylenes produced by binuclear metallocene catalysts (3, 4) and by mononuclear metallocene catalyst have only single peak, but the former (MWD = 3.54.7) is obviously broader than the latter (MWD = 2.02.2).
2006, 24(1): 29-34
Abstract:
The effect of vinyl acetate (VA) content in ethylene vinyl acetate (EVA) copolymer on the mechanical properties of polypropylene was investigated. Three different EVA copolymers with concentrations of 3 wt%, 6 wt%, 9 wt%, 12 wt% and 15 wt%, were blended to polypropylene. The mechanical properties such as yield and tensile strengths, elastic modulus, Izod impact strength, hardness and melt flow index of the blends were investigated. Relationship between type of vinyl acetate and concentrations, mechanical, MFI and morphological properties were explored.
The effect of vinyl acetate (VA) content in ethylene vinyl acetate (EVA) copolymer on the mechanical properties of polypropylene was investigated. Three different EVA copolymers with concentrations of 3 wt%, 6 wt%, 9 wt%, 12 wt% and 15 wt%, were blended to polypropylene. The mechanical properties such as yield and tensile strengths, elastic modulus, Izod impact strength, hardness and melt flow index of the blends were investigated. Relationship between type of vinyl acetate and concentrations, mechanical, MFI and morphological properties were explored.
2006, 24(1): 35-40
Abstract:
A new kind of binary hydrogels composed of poly(dimethylaminoethylmethacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) with varying weight average molecular weights ( = 5 104, 1 105 and 2.5 106) were prepared by γ-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of = 5 104, and the pH sensitivity was retained in samples with PEO of = 5 104 and 1 105. When DMAEMA/PEO mixtures containing PEO of = 5 104 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.
A new kind of binary hydrogels composed of poly(dimethylaminoethylmethacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) with varying weight average molecular weights ( = 5 104, 1 105 and 2.5 106) were prepared by γ-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of = 5 104, and the pH sensitivity was retained in samples with PEO of = 5 104 and 1 105. When DMAEMA/PEO mixtures containing PEO of = 5 104 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.
2006, 24(1): 41-46
Abstract:
Conventional chloromethylation, paraformaldehyde/hydrogen chloride in acetic acid medium, was applied to 1,2-dimethoxybenzene. Chloroform-soluble poly(3,4-dimethoxy-o-tolylene) was obtained with an intrinsic viscosity of 0.034 dL•g1. The polymer was evaluated as a condensation redox polymer precursor formed by a Friedel-Crafts reaction. Cleavage of the methoxy groups present in this polymer resulted in poly(3,4-dihydroxy-o-tolylene) which manifested a great air-oxidation resistance. The redox property of the latter polymer was found to be 1017 mV by potentiometric titration with 0.05 N ceric ammonium nitrate at 25℃. This midpotential was compared to that of catechol, a monomeric analogue, under the same titration conditions.
Conventional chloromethylation, paraformaldehyde/hydrogen chloride in acetic acid medium, was applied to 1,2-dimethoxybenzene. Chloroform-soluble poly(3,4-dimethoxy-o-tolylene) was obtained with an intrinsic viscosity of 0.034 dL•g1. The polymer was evaluated as a condensation redox polymer precursor formed by a Friedel-Crafts reaction. Cleavage of the methoxy groups present in this polymer resulted in poly(3,4-dihydroxy-o-tolylene) which manifested a great air-oxidation resistance. The redox property of the latter polymer was found to be 1017 mV by potentiometric titration with 0.05 N ceric ammonium nitrate at 25℃. This midpotential was compared to that of catechol, a monomeric analogue, under the same titration conditions.
2006, 24(1): 47-52
Abstract:
High quality poly(5-cyanoindole) (P5CI) films were electrosynthesized by direct anodic oxidation of 5-cyanoindole on stainless steel sheet in the mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and diethyl ether (EE) (by volume 1:1) + 0.05 mol L1 Bu4NBF4. The film formed can be peeled off the electrode into freestanding films. The addition of EE into BFEE can improve the solubility of monomer. P5CI films obtained from this medium showed excellent electrochemical behavior with conductivity of 102 S cm1. Structural studies showed that the polymerization of 5-cyanoindole occurred at the 2,3 position. As-formed P5CI films were thoroughly soluble in strong polar organic solvent dimethyl sulfoxide (DMSO) while partly soluble in tetrahydrofuran (THF) or acetone. Fluorescence spectral studies indicated that P5CI was a good blue-light emitter.
High quality poly(5-cyanoindole) (P5CI) films were electrosynthesized by direct anodic oxidation of 5-cyanoindole on stainless steel sheet in the mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and diethyl ether (EE) (by volume 1:1) + 0.05 mol L1 Bu4NBF4. The film formed can be peeled off the electrode into freestanding films. The addition of EE into BFEE can improve the solubility of monomer. P5CI films obtained from this medium showed excellent electrochemical behavior with conductivity of 102 S cm1. Structural studies showed that the polymerization of 5-cyanoindole occurred at the 2,3 position. As-formed P5CI films were thoroughly soluble in strong polar organic solvent dimethyl sulfoxide (DMSO) while partly soluble in tetrahydrofuran (THF) or acetone. Fluorescence spectral studies indicated that P5CI was a good blue-light emitter.
2006, 24(1): 53-60
Abstract:
Based on the premise that the addition of glass beads (GB) could hardly influence the linear viscoelasticity in low frequency (ω) region for homogeneous polymer systems, the dynamic rheological behaviors of unfilled and filled poly(methyl methyacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN) blends were studied in order to explore the effect of GB on the phase-separation of binary polymer matrix. Results show that GB has an induced effect on the phase-separation, which embodies that the phase-separation temperature (Ts) of PMMA/SAN blend filled with GB is lower than that of the unfilled system. The higher content of GB, the higher is the “secondary plateau” of in the terminal region of storage modulus (G) versus plot. The “secondary plateau” appearing in the terminal region is attributed to the phase-separation of PMMA/SAN blends and it becomes more flat for filled polymer blends under the same conditions. However, it is suggested that this kind of “induced effect” is related to the GB content; the higher content of GB particles might enhance the interaction between the particles and polymer matrix. Moreover，it is found that the addition of GB also has an influence more or less on the morphology and domain size of polymer matrix. It is believed that the plot of dynamic viscosity () versus the loss viscosity () is sensitive to examine the effect induced by GB on the phase-separation of binary polymer matrix.
Based on the premise that the addition of glass beads (GB) could hardly influence the linear viscoelasticity in low frequency (ω) region for homogeneous polymer systems, the dynamic rheological behaviors of unfilled and filled poly(methyl methyacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN) blends were studied in order to explore the effect of GB on the phase-separation of binary polymer matrix. Results show that GB has an induced effect on the phase-separation, which embodies that the phase-separation temperature (Ts) of PMMA/SAN blend filled with GB is lower than that of the unfilled system. The higher content of GB, the higher is the “secondary plateau” of in the terminal region of storage modulus (G) versus plot. The “secondary plateau” appearing in the terminal region is attributed to the phase-separation of PMMA/SAN blends and it becomes more flat for filled polymer blends under the same conditions. However, it is suggested that this kind of “induced effect” is related to the GB content; the higher content of GB particles might enhance the interaction between the particles and polymer matrix. Moreover，it is found that the addition of GB also has an influence more or less on the morphology and domain size of polymer matrix. It is believed that the plot of dynamic viscosity () versus the loss viscosity () is sensitive to examine the effect induced by GB on the phase-separation of binary polymer matrix.
2006, 24(1): 61-66
Abstract:
Adsorption behaviors of phenol from aqueous solutions have been investigated in batch systems at 303 K and 318 K respectively, using hypercrosslinked polymeric adsorbent (CHA111), aminated hypercrosslinked polymeric adsorbents (NDA101, NDA103, NDA105) and weakly basic polymeric adsorbent (D301) with a view to studying the effect of hydrogen bonding and Van der Waals interactions between adsorbate and the adsorbent. All adsorption isotherms can be well fitted by Langmuir and Freundlich equations. Compared with D301 driven by hydrogen bonding interaction only and CHA111 driven by Van der Waals interaction only, phenol adsorption on aminated adsorbents driven by both hydrogen bonding and Van der Waals interactions were apparently different, i.e., negative effect for NDA105, positive effect for NDA101 and synergistic effect for NDA103. In this synergistic action, some weak interactions would contribute more or less to the adsorption than they work individually.
Adsorption behaviors of phenol from aqueous solutions have been investigated in batch systems at 303 K and 318 K respectively, using hypercrosslinked polymeric adsorbent (CHA111), aminated hypercrosslinked polymeric adsorbents (NDA101, NDA103, NDA105) and weakly basic polymeric adsorbent (D301) with a view to studying the effect of hydrogen bonding and Van der Waals interactions between adsorbate and the adsorbent. All adsorption isotherms can be well fitted by Langmuir and Freundlich equations. Compared with D301 driven by hydrogen bonding interaction only and CHA111 driven by Van der Waals interaction only, phenol adsorption on aminated adsorbents driven by both hydrogen bonding and Van der Waals interactions were apparently different, i.e., negative effect for NDA105, positive effect for NDA101 and synergistic effect for NDA103. In this synergistic action, some weak interactions would contribute more or less to the adsorption than they work individually.
2006, 24(1): 67-72
Abstract:
A novel soluble and reactive amide-bridged ladderlike polyhydrosiloxane (ALPHS) was first synthesized by an amido H-bonding self-assembled template. ALPHS with molecular weight = 18300 has very highly ordered ladderlike structure, which was confirmed by a sharp resonance absorption peak of [―Si(H)O2/2 ] moiety with the half peak width 1/2 < 0.5 in 29Si-NMR spectrum. Presence of the reactive Si―H groups gives ALPHS an opportunity to further derive a variety of functional polymers by versatile Si―H reactions such as hydrosilylation, condensation, and so on.
A novel soluble and reactive amide-bridged ladderlike polyhydrosiloxane (ALPHS) was first synthesized by an amido H-bonding self-assembled template. ALPHS with molecular weight = 18300 has very highly ordered ladderlike structure, which was confirmed by a sharp resonance absorption peak of [―Si(H)O2/2 ] moiety with the half peak width 1/2 < 0.5 in 29Si-NMR spectrum. Presence of the reactive Si―H groups gives ALPHS an opportunity to further derive a variety of functional polymers by versatile Si―H reactions such as hydrosilylation, condensation, and so on.
2006, 24(1): 73-80
Abstract:
The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.
The binary adsorption behavior of 1-naphthol/1-naphthylamine mixtures in water on nonpolar adsorbent Amberlite XAD4 was investigated at 293 K, 303 K and 313 K, respectively. The experimental uptakes of 1-naphthol and 1-naphthylamine in all binary-component systems of different molar ratios were obviously higher than the corresponding uptakes predicted by the extended Langmuir model, assuming no interaction between the adsorbed molecules of the two components. This phenomenon was attributed to the cooperative adsorption effect arising from the hydrogen bonding interaction between 1-naphthol and 1-naphthylamine molecules. A modified extended Langmuir model was proposed to describe the binary adsorption behavior by means of introducing a fitting parameter related with the cooperative adsorption effect of the adsorbates.
2006, 24(1): 81-86
Abstract:
A series of polymeric complexes were prepared from Fe2+, Co2+ or Ni2+ and poly(Schiff base) (DAPcIPA), which was obtained by polycondensation of 5,6-diamino-1,10-phenanthroline (DAP) with isophthalaldehyde (IPA). The structures of the polymer and the polymeric complexes were characterized by IR, 1H-NMR and elemental analysis. The magnetic behavior of these complexes was measured as a function of magnetic field strength (03.98 106 A/m) at 5 K and as a function of temperature (5300 K) at a magnetic field strength of 2.39 106 A/m. Experimental results show that DAPcIPA-Ni2+, DAPcIPA-Co2+ are soft ferromagnets while DAPcIPA-Fe2+exhibits features of an antiferromagnet.
A series of polymeric complexes were prepared from Fe2+, Co2+ or Ni2+ and poly(Schiff base) (DAPcIPA), which was obtained by polycondensation of 5,6-diamino-1,10-phenanthroline (DAP) with isophthalaldehyde (IPA). The structures of the polymer and the polymeric complexes were characterized by IR, 1H-NMR and elemental analysis. The magnetic behavior of these complexes was measured as a function of magnetic field strength (03.98 106 A/m) at 5 K and as a function of temperature (5300 K) at a magnetic field strength of 2.39 106 A/m. Experimental results show that DAPcIPA-Ni2+, DAPcIPA-Co2+ are soft ferromagnets while DAPcIPA-Fe2+exhibits features of an antiferromagnet.
2006, 24(1): 87-93
Abstract:
An improved configurational-confomational statistical method is developed and the mean-square radius of gyration for atactic poly(-methylstyrene)(PMS) chains is studied, in which the effect of large side groups is considered. The deduced formulas, based on the rotational isomer state theory, are used to investigate the configuration-dependent properties of the atactic polymer chain, and the statistical correlation of the unperturbed polymer chain dimension and structure parameters are calculated. For the fraction of meso dyads wm = 0.4, the dependence of the radius of gyration Rg and the intrinsic viscosity [] on the molecule mass M are Rg = 2.63 102 M0.50 nm and [] = 7.36 102 M0.497, respectively, which are in agreement with the previous experimental data for the PMS samples. A small hump is detected in the curve of the characteristic ratio of the unperturbed mean-square radius of gyration versus the chain length for short PMS chains. The Rg increases linearly with the temperature T, and the effects of the chain length and the tacticity on the temperature coefficient are remarkable. These are quite different from the results for PMS chains not considering side groups or for the monosubstituted polystyrene chain.
An improved configurational-confomational statistical method is developed and the mean-square radius of gyration for atactic poly(-methylstyrene)(PMS) chains is studied, in which the effect of large side groups is considered. The deduced formulas, based on the rotational isomer state theory, are used to investigate the configuration-dependent properties of the atactic polymer chain, and the statistical correlation of the unperturbed polymer chain dimension and structure parameters are calculated. For the fraction of meso dyads wm = 0.4, the dependence of the radius of gyration Rg and the intrinsic viscosity [] on the molecule mass M are Rg = 2.63 102 M0.50 nm and [] = 7.36 102 M0.497, respectively, which are in agreement with the previous experimental data for the PMS samples. A small hump is detected in the curve of the characteristic ratio of the unperturbed mean-square radius of gyration versus the chain length for short PMS chains. The Rg increases linearly with the temperature T, and the effects of the chain length and the tacticity on the temperature coefficient are remarkable. These are quite different from the results for PMS chains not considering side groups or for the monosubstituted polystyrene chain.
2006, 24(1): 95-101
Abstract:
2006, 24(1): 103-106
Abstract:
In this work, the membrane surface of poly(acrylonitrile-co-2-hydroxyethyl methacrylate) (PANCHEMA) was chemically modified by anchoring of phospholipid moieties. The process involved the reaction of hydroxyl groups on the membrane surface with 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) followed by the ring-opening reaction of COP with trimethylamine. Chemical differences between the original and the modified membranes were characterized by FT-IR and XPS. It was found that the amount of macrophage adhered on the modified membrane surface is substantially lower than that on polyacrylonitrile (PAN) and PANCHEMA membranes under the same condition. The morphological change of the adherent cell is also suppressed by the generation of phospholipid moieties on the membrane surface.
In this work, the membrane surface of poly(acrylonitrile-co-2-hydroxyethyl methacrylate) (PANCHEMA) was chemically modified by anchoring of phospholipid moieties. The process involved the reaction of hydroxyl groups on the membrane surface with 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) followed by the ring-opening reaction of COP with trimethylamine. Chemical differences between the original and the modified membranes were characterized by FT-IR and XPS. It was found that the amount of macrophage adhered on the modified membrane surface is substantially lower than that on polyacrylonitrile (PAN) and PANCHEMA membranes under the same condition. The morphological change of the adherent cell is also suppressed by the generation of phospholipid moieties on the membrane surface.
