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2010 Volume 28 Issue 6
2010, 28(6): 849-857
doi: 10.1007/s10118-010-9142-6
Abstract:
The interpenetrating polymer network (IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane (TRIS), 2-hydroxyethylmethacrylate (HEMA) and N-vinyl pyrrolidone (NVP) in the presence of free radical photoinitiator and cationic photoinitiator. The polymerization mechanism was investigated by the formation of gel network. The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results showed that the IPN hydrogels exhibited a heterogeneous morphology. The mechanical properties, surface wettability and oxygen permeability were examined by using a tensile tester, a contact angle goniometer and an oxygen transmission tester, respectively. The equilibrium water content of the hydrogels was measured by the gravimetric method. The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content. They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.
The interpenetrating polymer network (IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane (TRIS), 2-hydroxyethylmethacrylate (HEMA) and N-vinyl pyrrolidone (NVP) in the presence of free radical photoinitiator and cationic photoinitiator. The polymerization mechanism was investigated by the formation of gel network. The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results showed that the IPN hydrogels exhibited a heterogeneous morphology. The mechanical properties, surface wettability and oxygen permeability were examined by using a tensile tester, a contact angle goniometer and an oxygen transmission tester, respectively. The equilibrium water content of the hydrogels was measured by the gravimetric method. The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content. They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.
2010, 28(6): 859-867
doi: 10.1007/s10118-010-9153-3
Abstract:
A potential biodegradable and optically active bulky chiral aromatic amide-imidic diacid monomer, (2S,3S)-5-(3-methyl-2-phthalimidylpentanoylamino)isophthalic acid (7), containing a rigid phthalimide and flexible L-isoleucine pendant group was synthesized in three steps. New aromatic polyamides including pendant phthalimido groups and flexible side spacers have been synthesized by direct polycondensation reaction of equimolar amounts of different aromatic diamines with an optically active diacid 7, using N-methyl-2-pyrrolidone (NMP) as a solvent and triphenyl phosphite/CaCl2/pyridine as a condensing agent. These polyamides were characterized by FTIR, 1H-NMR spectroscopy, specific rotation, thermogravimetric and elemental analysis. The resulting polymers have inherent viscosities in the range of 0.21-0.45 dL/g. Amino acid existence in this backbone results in optically active polymers. Due to introduction of bulky and flexible groups in these polyamides, they show improved solubility in polar aprotic solvents such as NMP and dimethylacetamide and also good thermal stability (10% weight loss temperatures in excess of 330°C, and char yields at 600°C in nitrogen higher than 62%).
A potential biodegradable and optically active bulky chiral aromatic amide-imidic diacid monomer, (2S,3S)-5-(3-methyl-2-phthalimidylpentanoylamino)isophthalic acid (7), containing a rigid phthalimide and flexible L-isoleucine pendant group was synthesized in three steps. New aromatic polyamides including pendant phthalimido groups and flexible side spacers have been synthesized by direct polycondensation reaction of equimolar amounts of different aromatic diamines with an optically active diacid 7, using N-methyl-2-pyrrolidone (NMP) as a solvent and triphenyl phosphite/CaCl2/pyridine as a condensing agent. These polyamides were characterized by FTIR, 1H-NMR spectroscopy, specific rotation, thermogravimetric and elemental analysis. The resulting polymers have inherent viscosities in the range of 0.21-0.45 dL/g. Amino acid existence in this backbone results in optically active polymers. Due to introduction of bulky and flexible groups in these polyamides, they show improved solubility in polar aprotic solvents such as NMP and dimethylacetamide and also good thermal stability (10% weight loss temperatures in excess of 330°C, and char yields at 600°C in nitrogen higher than 62%).
2010, 28(6): 869-876
doi: 10.1007/s10118-010-9157-z
Abstract:
An innovational method that poly(styrene-co-maleic anhydride) (SMA), a compatibilizer of immiscible nylon6/polystyrene (PA6/PS) blends, was first reacted with carbon black (CB) and then blended with PA6/PS, has been employed to prepare the PA6/PS/(SMA-CB) composites of which CB localized at the interface. In PA6/PS/CB blends, CB was found to preferentially localize in the PA6 phase. However, in the PA6/PS/(SMA-CB) blends, it was found that CB particles can be induced by SMA to localize at the interface. The electrical porperties of PA6/PS/(SMA-CB) composites were investigated. The results showed that the composites exhibited distinct triple percolation behavior, i.e. the percolation is governed by the percolation of CB in SMA phase, the continuity of SMA-CB at the interface and the continuity of PA6/PS interface. The percolation threshold of PA6/PS/(SMA-CB) was only 0.15 wt%, which is much lower than that of PA6/PS/CB. Moreover, the PTC (positive temperature coefficient) intensity of PA6/PS/(SMA-CB) composites was stronger than that of PA6/PS/CB and the negative temperature coefficient (NTC) effect was eliminated. The electrical properties of PA6/PS/(SMA-CB) were explained in terms of its special interface morphology: SMA and CB localize at interphase to form the conductive pathways.
An innovational method that poly(styrene-co-maleic anhydride) (SMA), a compatibilizer of immiscible nylon6/polystyrene (PA6/PS) blends, was first reacted with carbon black (CB) and then blended with PA6/PS, has been employed to prepare the PA6/PS/(SMA-CB) composites of which CB localized at the interface. In PA6/PS/CB blends, CB was found to preferentially localize in the PA6 phase. However, in the PA6/PS/(SMA-CB) blends, it was found that CB particles can be induced by SMA to localize at the interface. The electrical porperties of PA6/PS/(SMA-CB) composites were investigated. The results showed that the composites exhibited distinct triple percolation behavior, i.e. the percolation is governed by the percolation of CB in SMA phase, the continuity of SMA-CB at the interface and the continuity of PA6/PS interface. The percolation threshold of PA6/PS/(SMA-CB) was only 0.15 wt%, which is much lower than that of PA6/PS/CB. Moreover, the PTC (positive temperature coefficient) intensity of PA6/PS/(SMA-CB) composites was stronger than that of PA6/PS/CB and the negative temperature coefficient (NTC) effect was eliminated. The electrical properties of PA6/PS/(SMA-CB) were explained in terms of its special interface morphology: SMA and CB localize at interphase to form the conductive pathways.
2010, 28(6): 877-885
doi: 10.1007/s10118-010-9160-4
Abstract:
A benzocyclobuten-4-yl acrylate (1) monomer was prepared by esterification of 4-hydroxybenzocyclobutene with acryloyl chloride. The radical homopolymerization of 1 and copolymerization of 1 with styrene or n-butyl acrylate were carried out to produce linear polymers 2a, 2b and 2c. Heating of these linear polymers under thermal initiation gave corresponding cross-linked polymers 3a, 3b and 3c. The ring-opening reaction in the cross-linking process was confirmed by on-line infrared spectra. Differential scanning calorimetry showed that the glass transition temperatures of linear polymers 2a and 2b were 83.2°C and 68.1°C, respectively. Thermogravimetric analysis of the cross-linked polymers showed that they all exhibited good thermal stability.
A benzocyclobuten-4-yl acrylate (1) monomer was prepared by esterification of 4-hydroxybenzocyclobutene with acryloyl chloride. The radical homopolymerization of 1 and copolymerization of 1 with styrene or n-butyl acrylate were carried out to produce linear polymers 2a, 2b and 2c. Heating of these linear polymers under thermal initiation gave corresponding cross-linked polymers 3a, 3b and 3c. The ring-opening reaction in the cross-linking process was confirmed by on-line infrared spectra. Differential scanning calorimetry showed that the glass transition temperatures of linear polymers 2a and 2b were 83.2°C and 68.1°C, respectively. Thermogravimetric analysis of the cross-linked polymers showed that they all exhibited good thermal stability.
2010, 28(6): 887-894
doi: 10.1007/s10118-010-9176-9
Abstract:
The existence of interfacial instability at the interface of multilayer polymeric flows is well known. This article is designed mainly to provide guidelines for the development of experimental techniques for the improvement of two-layer polymer products in the polymer processing industry. This is done by performing a series of tensile tests on extrudate two-layer polymer melts in order to get insight into the relation between interfacial wave and mechanical properties of LLDPE/HDPE polymer system. Observed variations of the mechanical properties have been related to the conformation of the interfacial wave so that a relationship between interface morphology corresponding to extrusion instabilities and mechanical characteristics of the interfacial strength for polymer melts extrudate is established.
The existence of interfacial instability at the interface of multilayer polymeric flows is well known. This article is designed mainly to provide guidelines for the development of experimental techniques for the improvement of two-layer polymer products in the polymer processing industry. This is done by performing a series of tensile tests on extrudate two-layer polymer melts in order to get insight into the relation between interfacial wave and mechanical properties of LLDPE/HDPE polymer system. Observed variations of the mechanical properties have been related to the conformation of the interfacial wave so that a relationship between interface morphology corresponding to extrusion instabilities and mechanical characteristics of the interfacial strength for polymer melts extrudate is established.
2010, 28(6): 895-902
doi: 10.1007/s10118-010-9168-9
Abstract:
A generic method was described to change surface biocompatibility by introducing reactive functional groups onto surfaces of polymeric substrates and covalently binding them with biomolecules. A block copolymer with protected carboxylic acid functionality, poly(styrene-b-tert-butyl acrylate) (PS-PtBA), was spin coated from solutions in toluene on a bioinert polystyrene (PS) substrate to form a bilayer structure: a surface layer of the poly(tert-butyl acrylate) (PtBA) blocks that order at the air-polymer interface and a bottom layer of the PS blocks that entangle with the PS substrate. The thickness of the PtBA layer and the area density of tert-butyl ester groups of PtBA increased linearly with the concentration of the spin coating solution until a 2 nm saturated monolayer coverage of PtBA was achieved at the concentration of 0.4% W/W. The protected carboxylic acid groups were generated by exposing the tert-butyl ester groups of PtBA to trifluoroacetic acid (TFA) for bioconjugation with FMRF peptides via amide bonds. The yield of the bioconjugation reaction for the saturated surface was calculated to be 37.1% based on X-ray photoelectron spectroscopy (XPS) measurements. The success of each functionalization step was demonstrated and characterized by XPS and contact angle measurements. This polymer functionalization/modification concept can be virtually applied to any polymeric substrate by choosing appropriate functional block copolymers and biomolecules to attain novel biocompatibility.
A generic method was described to change surface biocompatibility by introducing reactive functional groups onto surfaces of polymeric substrates and covalently binding them with biomolecules. A block copolymer with protected carboxylic acid functionality, poly(styrene-b-tert-butyl acrylate) (PS-PtBA), was spin coated from solutions in toluene on a bioinert polystyrene (PS) substrate to form a bilayer structure: a surface layer of the poly(tert-butyl acrylate) (PtBA) blocks that order at the air-polymer interface and a bottom layer of the PS blocks that entangle with the PS substrate. The thickness of the PtBA layer and the area density of tert-butyl ester groups of PtBA increased linearly with the concentration of the spin coating solution until a 2 nm saturated monolayer coverage of PtBA was achieved at the concentration of 0.4% W/W. The protected carboxylic acid groups were generated by exposing the tert-butyl ester groups of PtBA to trifluoroacetic acid (TFA) for bioconjugation with FMRF peptides via amide bonds. The yield of the bioconjugation reaction for the saturated surface was calculated to be 37.1% based on X-ray photoelectron spectroscopy (XPS) measurements. The success of each functionalization step was demonstrated and characterized by XPS and contact angle measurements. This polymer functionalization/modification concept can be virtually applied to any polymeric substrate by choosing appropriate functional block copolymers and biomolecules to attain novel biocompatibility.
2010, 28(6): 903-922
doi: 10.1007/s10118-010-9167-x
Abstract:
The aim of this work is to investigate the hydrogen-bonding interaction in poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAA) blending system and its influence on rheological properties in solution and the physical properties in solid state. Introducing PAA into PVA solutions resulted in a thickening behavior of blend solutions. The viscosity of the solutions increased with PAA content increasing, and a maximum viscosity could be obtained when the ratio of PVA/PAA was 70/30. The intermolecular hydrogen-bonding and miscibility between PVA and PAA in solid state were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and mechanical measurements. The results displayed the great influence of introducing PAA on the properties of blending films. The tensile strength increased from 89.31 MPa to 119.8 MPa and Young’s modulus improved by over 300% with increasing PAA concentration compared with those of pure PVA films. By systematically studying the rheological behaviors of solutions and the physical properties of films, the influence of hydrogen-bonding in solutions and solid states were discussed.
The aim of this work is to investigate the hydrogen-bonding interaction in poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAA) blending system and its influence on rheological properties in solution and the physical properties in solid state. Introducing PAA into PVA solutions resulted in a thickening behavior of blend solutions. The viscosity of the solutions increased with PAA content increasing, and a maximum viscosity could be obtained when the ratio of PVA/PAA was 70/30. The intermolecular hydrogen-bonding and miscibility between PVA and PAA in solid state were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and mechanical measurements. The results displayed the great influence of introducing PAA on the properties of blending films. The tensile strength increased from 89.31 MPa to 119.8 MPa and Young’s modulus improved by over 300% with increasing PAA concentration compared with those of pure PVA films. By systematically studying the rheological behaviors of solutions and the physical properties of films, the influence of hydrogen-bonding in solutions and solid states were discussed.
2010, 28(6): 913-922
doi: 10.1007/s10118-010-9173-z
Abstract:
Unsaturated polyester (UPR)/thermoplastic polyurethane (TPU)/organoclay nanocomposites were prepared by melt compounding of thermoplastic polyurethane and unsaturated polyester prepolymer, and then mixing with the hybrids of styrene monomers and organoclay at ambient temperature. The crosslinking reaction eventually occurred through the unsaturated polyester prepolymer and styrene monomer. The morphology of the composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the impact strength of UPR/TPU/organoclay nanocomposites increases obviously; the cure shrinkage decreases markedly, the glass transition temperature is enhanced and an elastic response to the deformation is prominent at the temperature above 10oC.
Unsaturated polyester (UPR)/thermoplastic polyurethane (TPU)/organoclay nanocomposites were prepared by melt compounding of thermoplastic polyurethane and unsaturated polyester prepolymer, and then mixing with the hybrids of styrene monomers and organoclay at ambient temperature. The crosslinking reaction eventually occurred through the unsaturated polyester prepolymer and styrene monomer. The morphology of the composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the impact strength of UPR/TPU/organoclay nanocomposites increases obviously; the cure shrinkage decreases markedly, the glass transition temperature is enhanced and an elastic response to the deformation is prominent at the temperature above 10oC.
2010, 28(6): 923-930
doi: 10.1007/s10118-010-9175-x
Abstract:
Polypyrrole (PPy) shows a favorable application in the electromagnetic interference (EMI) shielding due to its good electrical conductivity and outstanding air stability. Conducting PPy films with high conductivity and good adhesion were successfully polymerized on the surface of insulating epoxy resin substrates using chemical polymerization. The factors affecting the properties of PPy films, such as the surface morphology, adhesion between PPy film and substrate, electrical conductivity, EMI shielding effectiveness (SE), were investigated. The adhesion was improved significantly through a three-step surface pretreatment of epoxy resin substrates including removing impurities, roughening, and surface modification with silane coupling agent. An enhancement in the conductivity of PPy films of about one order of magnitude was achieved by adding dopant in FeCl3 solution. The higher the conductivity, the better the shielding effectiveness. Taking sodium p-toluenesulfonate doped PPy film as example, EMI SE was in the practically useful range of about 30 dB over a wide frequency range from 30 MHz to 1500 MHz. The PPy film samples were characterized by scanning electron microscopy (SEM), infrared spectra (IR), X-ray photoelectron spectroscopy (XPS) and the flange coaxial transmission device. The four-point probe method was used to measure conductivity of PPy films.
Polypyrrole (PPy) shows a favorable application in the electromagnetic interference (EMI) shielding due to its good electrical conductivity and outstanding air stability. Conducting PPy films with high conductivity and good adhesion were successfully polymerized on the surface of insulating epoxy resin substrates using chemical polymerization. The factors affecting the properties of PPy films, such as the surface morphology, adhesion between PPy film and substrate, electrical conductivity, EMI shielding effectiveness (SE), were investigated. The adhesion was improved significantly through a three-step surface pretreatment of epoxy resin substrates including removing impurities, roughening, and surface modification with silane coupling agent. An enhancement in the conductivity of PPy films of about one order of magnitude was achieved by adding dopant in FeCl3 solution. The higher the conductivity, the better the shielding effectiveness. Taking sodium p-toluenesulfonate doped PPy film as example, EMI SE was in the practically useful range of about 30 dB over a wide frequency range from 30 MHz to 1500 MHz. The PPy film samples were characterized by scanning electron microscopy (SEM), infrared spectra (IR), X-ray photoelectron spectroscopy (XPS) and the flange coaxial transmission device. The four-point probe method was used to measure conductivity of PPy films.
2010, 28(6): 931-939
doi: 10.1007/s10118-010-9178-7
Abstract:
Two novel copolymers based on benzothiadizole-thiophene-phenylenevinylene have been synthesized through palladium catalyzed triple-bond polycondensation method. The copolymers exhibit good solubility in common organic solvents such as CHCl3, CH2Cl2 and THF. The structures and properties of the two copolymers are characterized by FT-IR, 1H-NMR, UV-Vis absorbance (Abs), gel permeation chromatography (GPC), thermal gravimetric analysis and cyclic voltammetry (CV). The copolymers of P1 and P2 show absorption spectra with maximum peak at 532 nm and 573 nm in solution, respectively. Compare to their monomers M1 and M2, the absorption peaks of P1 and P2 were red-shifted by 34 nm and 54 nm respectively. Thermal gravimetric analysis demonstrated that the polymers were stable and little weight loss was observed below 300oC. Cyclic voltammetry experiments showed that the band gaps of the copolymers were 1.81 eV and 1.62 eV, respectively, suggesting their potential for applications as organic solar cell materials.
Two novel copolymers based on benzothiadizole-thiophene-phenylenevinylene have been synthesized through palladium catalyzed triple-bond polycondensation method. The copolymers exhibit good solubility in common organic solvents such as CHCl3, CH2Cl2 and THF. The structures and properties of the two copolymers are characterized by FT-IR, 1H-NMR, UV-Vis absorbance (Abs), gel permeation chromatography (GPC), thermal gravimetric analysis and cyclic voltammetry (CV). The copolymers of P1 and P2 show absorption spectra with maximum peak at 532 nm and 573 nm in solution, respectively. Compare to their monomers M1 and M2, the absorption peaks of P1 and P2 were red-shifted by 34 nm and 54 nm respectively. Thermal gravimetric analysis demonstrated that the polymers were stable and little weight loss was observed below 300oC. Cyclic voltammetry experiments showed that the band gaps of the copolymers were 1.81 eV and 1.62 eV, respectively, suggesting their potential for applications as organic solar cell materials.
2010, 28(6): 941-949
doi: 10.1007/s10118-010-9182-y
Abstract:
New organo-soluble poly(amide-imide)s (PAIs) 8a-8f were prepared from newly synthesized 1,2-bis[4,4’-(trimellitimido)phenoxy]ethane 6 via direct polycondensation with various aromatic diamines. The diacid 6 was synthesized by the condensation reaction of 1,2-bis[4-aminophenoxy]ethane 4 with trimellitic anhydride 5 in acetic acid. All polymers were obtained in quantitative high yields with inherent viscosities of 0.48-0.61 dL/g. All of these polymers were highly soluble in organic solvents such as, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), N,N’-dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) at room temperature and were fully characterized by means of NMR spectroscopy, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
New organo-soluble poly(amide-imide)s (PAIs) 8a-8f were prepared from newly synthesized 1,2-bis[4,4’-(trimellitimido)phenoxy]ethane 6 via direct polycondensation with various aromatic diamines. The diacid 6 was synthesized by the condensation reaction of 1,2-bis[4-aminophenoxy]ethane 4 with trimellitic anhydride 5 in acetic acid. All polymers were obtained in quantitative high yields with inherent viscosities of 0.48-0.61 dL/g. All of these polymers were highly soluble in organic solvents such as, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), N,N’-dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) at room temperature and were fully characterized by means of NMR spectroscopy, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
2010, 28(6): 951-959
doi: 10.1007/s10118-010-9191-x
Abstract:
Poly(maleic anhydride-co-acrylic acid), P(MA-AA), was synthesized by the free-radical copolymerization of maleic anhydride with acrylic acid, and fast responsive pH-sensitive poly(maleic anhydride-co-acrylic acid)/polyethylene glycol, P(MA-AA)/PEG, hydrogels were prepared using PEG as macromolecular cross-linking agent. FT-IR and 1H-NMR spectrometry were applied to characterize the structure of P(MA-AA). The influences of pH and ionic strength on the swelling behavior of P(MA-AA)/PEG hydrogels and the swelling-deswelling changes along with the repeated changes between acid and alkali conditions were studied. The results showed that there was a hundredfold difference in the swelling ratios between the conditions of acid and alkali, and the swelling capability could not be weakened after multiple swelling-deswelling cycles. The results of swelling kinetics demonstrated that the response rate of P(MA-AA)/PEG hydrogels was very fast, because the swelling transition points always occurred at 10 min. The pH-responsive hydrogels reported here might be a smart material for potentially applications in many areas, including biosensors, drug-delivery devices and tissue engineering.
Poly(maleic anhydride-co-acrylic acid), P(MA-AA), was synthesized by the free-radical copolymerization of maleic anhydride with acrylic acid, and fast responsive pH-sensitive poly(maleic anhydride-co-acrylic acid)/polyethylene glycol, P(MA-AA)/PEG, hydrogels were prepared using PEG as macromolecular cross-linking agent. FT-IR and 1H-NMR spectrometry were applied to characterize the structure of P(MA-AA). The influences of pH and ionic strength on the swelling behavior of P(MA-AA)/PEG hydrogels and the swelling-deswelling changes along with the repeated changes between acid and alkali conditions were studied. The results showed that there was a hundredfold difference in the swelling ratios between the conditions of acid and alkali, and the swelling capability could not be weakened after multiple swelling-deswelling cycles. The results of swelling kinetics demonstrated that the response rate of P(MA-AA)/PEG hydrogels was very fast, because the swelling transition points always occurred at 10 min. The pH-responsive hydrogels reported here might be a smart material for potentially applications in many areas, including biosensors, drug-delivery devices and tissue engineering.
2010, 28(6): 961-969
doi: 10.1007/s10118-010-0033-7
Abstract:
A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A (DGEBA) and flexible α,β-bisamino(n-alkylene)phenyl terminated poly(ethylene glycol). The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers (ATPE) on the mechanical properties, fractographs and curing kinetics of the ATPE-DGEBA cured products were studied. The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE, on one hand, can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products, resulting in slight decrease of the Young’s modulus and tensile strength, and significant increase of the toughness and elongation of the ATPE-DGEBA cured products. On the other hand, it can remarkably enhance the reactivity of amine with epoxy, much accelerating the curing rate of the ATPE-DGEBA systems. The activation energy of DGEBA cured by BAPTPE, BAMPTPE and BAEPTPE was 53.1, 28.5 and 25.4 kJ.mol-1, respectively. The as-obtained ATPE-DGEBA cured products are homogeneous, transparent, and show excellent mechanical properties including tensile strength and toughness. Thus they are promising to have important applications in structure adhesives, casting bulk materials, functional coatings, cryogenic engineering, damping and sound absorbing materials.
A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A (DGEBA) and flexible α,β-bisamino(n-alkylene)phenyl terminated poly(ethylene glycol). The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers (ATPE) on the mechanical properties, fractographs and curing kinetics of the ATPE-DGEBA cured products were studied. The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE, on one hand, can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products, resulting in slight decrease of the Young’s modulus and tensile strength, and significant increase of the toughness and elongation of the ATPE-DGEBA cured products. On the other hand, it can remarkably enhance the reactivity of amine with epoxy, much accelerating the curing rate of the ATPE-DGEBA systems. The activation energy of DGEBA cured by BAPTPE, BAMPTPE and BAEPTPE was 53.1, 28.5 and 25.4 kJ.mol-1, respectively. The as-obtained ATPE-DGEBA cured products are homogeneous, transparent, and show excellent mechanical properties including tensile strength and toughness. Thus they are promising to have important applications in structure adhesives, casting bulk materials, functional coatings, cryogenic engineering, damping and sound absorbing materials.
2010, 28(6): 971-980
doi: 10.1007/s10118-010-1011-9
Abstract:
A novel fluorene-bridged tetraketone monomer, 9,9-bis[(4-benzilyloxy)phenyl]fluorene (FLTK) was synthesized and characterized. The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyphenylquinoxalines (PPQs). The obtained polymers were found to be soluble in common organic solvents such as N-methyl-2-pyrrolidone (NMP), chloroform and m-cresol. Flexible and tough PPQ films obtained by spin-casting their NMP solutions exhibited tensile strengths higher than 60 MPa. The films also demonstrated good thermal stability up to 500oC in nitrogen and glass transition temperatures higher than 280oC. In addition, the PPQ films exhibited good hydrolytic stability. High surface and volume resistivity retentions were achieved for the films after immersion or boiling in water for 24 h.
A novel fluorene-bridged tetraketone monomer, 9,9-bis[(4-benzilyloxy)phenyl]fluorene (FLTK) was synthesized and characterized. The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyphenylquinoxalines (PPQs). The obtained polymers were found to be soluble in common organic solvents such as N-methyl-2-pyrrolidone (NMP), chloroform and m-cresol. Flexible and tough PPQ films obtained by spin-casting their NMP solutions exhibited tensile strengths higher than 60 MPa. The films also demonstrated good thermal stability up to 500oC in nitrogen and glass transition temperatures higher than 280oC. In addition, the PPQ films exhibited good hydrolytic stability. High surface and volume resistivity retentions were achieved for the films after immersion or boiling in water for 24 h.
