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2012 Volume 30 Issue 4
2012, 30(4): 487-492
doi: 10.1007/s10118-012-1171-x
Abstract:
An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly(cyclohexene carbonate) (PCHC) has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point (Tm) of 215-230癈 and a decomposition temperature of ca. 310癈. The spherulitic morphology of (R)-PCHC grows in a clockwise spiral from a center, and that of (S)-PCHC is a counterclockwise spiral, while the stereocomplex of (S)-PCHC/(R)-PCHC (1/1 mass ratio) presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.
An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly(cyclohexene carbonate) (PCHC) has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point (Tm) of 215-230癈 and a decomposition temperature of ca. 310癈. The spherulitic morphology of (R)-PCHC grows in a clockwise spiral from a center, and that of (S)-PCHC is a counterclockwise spiral, while the stereocomplex of (S)-PCHC/(R)-PCHC (1/1 mass ratio) presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.
2012, 30(4): 493-502
doi: 10.1007/s10118-012-1166-7
Abstract:
A novel liquid hyperbranched polyether epoxy (HBPEE) based on commercially available hydroquinone (HQ) and 1,1,1-trihydroxymethylpropane triglycidyl ether (TMPGE) was synthesized through an A2 + B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A (DGEBA) in different ratios to form hybrids and cured with triethylenetetramine (TETA). Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature (Tg) of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.
A novel liquid hyperbranched polyether epoxy (HBPEE) based on commercially available hydroquinone (HQ) and 1,1,1-trihydroxymethylpropane triglycidyl ether (TMPGE) was synthesized through an A2 + B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A (DGEBA) in different ratios to form hybrids and cured with triethylenetetramine (TETA). Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature (Tg) of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.
2012, 30(4): 503-510
doi: 10.1007/s10118-012-1132-4
Abstract:
Conjugated ployfluorene with 2-(2-(2-methoxyethoxy)ethoxy)ethyl groups (EO-PF) is prepared by the palladiumcatalyzed Suzuki coupling reaction. The polymer is purified carefully by a simple chemical procedure. The inductively coupled plasma (ICP) test shows palladium-catalyst in the polymer can be removed by this procedure. The thermal properties, electrochemical properties, UV-Vis absorption properties, photoluminescence properties and electroluminescent properties of the polymer without (EO-PF1) or with purification (EO-PF2) are studied. EO-PF2 shows better PL CIE coordinates in THF solutions as blue light-emitting materials and better photoluminescence stability in thin solid films. Polymer light emitting diodes and electrochemical cells based on EO-PF2 exhibit somewhat improved optoelectronic performance than control devices of EO-PF1.
Conjugated ployfluorene with 2-(2-(2-methoxyethoxy)ethoxy)ethyl groups (EO-PF) is prepared by the palladiumcatalyzed Suzuki coupling reaction. The polymer is purified carefully by a simple chemical procedure. The inductively coupled plasma (ICP) test shows palladium-catalyst in the polymer can be removed by this procedure. The thermal properties, electrochemical properties, UV-Vis absorption properties, photoluminescence properties and electroluminescent properties of the polymer without (EO-PF1) or with purification (EO-PF2) are studied. EO-PF2 shows better PL CIE coordinates in THF solutions as blue light-emitting materials and better photoluminescence stability in thin solid films. Polymer light emitting diodes and electrochemical cells based on EO-PF2 exhibit somewhat improved optoelectronic performance than control devices of EO-PF1.
2012, 30(4): 511-519
doi: 10.1007/s10118-012-1129-z
Abstract:
Sulfonated poly(ether ketone)s containing 3,5-dimethyl phthalazinone moieties (SPPEK-DMs) with different degrees of sulfonation (DS) were synthesized via direct polycondensation from 4-(3,5-dimethyl-4-hydroxyphenyl)-2,3- phthalazinone, 4,4-difluorobenzophenone and 3,3-disulfonate-4,4-difluorobenzophenone. The chemical structure of SPPEK-DMs was characterized by FTIR and 1H-NMR. Thermal stability of SPPEK-DMs was characterized by the thermogravimetric analysis. The membranes prepared from SPPEK-DMs exhibited ion exchange capacities (IEC) ranging from 0.93 mmolg-1 to 1.86 mmolg-1. Water uptake, swelling, oxidative stability and methanol permeability of SPPEKDMs membranes were investigated. SPPEK-DMs membranes exhibited high oxidative stability. The methanol permeability values of SPPEK-DMs membranes were in the range 5.15 10-8-6.61 10-7 cm2s-1, which was much lower than those of Nafion117. The proton conductivity of SPPEK-DM40 membranes was 1.1 10-2 Scm-1 at 70C.
Sulfonated poly(ether ketone)s containing 3,5-dimethyl phthalazinone moieties (SPPEK-DMs) with different degrees of sulfonation (DS) were synthesized via direct polycondensation from 4-(3,5-dimethyl-4-hydroxyphenyl)-2,3- phthalazinone, 4,4-difluorobenzophenone and 3,3-disulfonate-4,4-difluorobenzophenone. The chemical structure of SPPEK-DMs was characterized by FTIR and 1H-NMR. Thermal stability of SPPEK-DMs was characterized by the thermogravimetric analysis. The membranes prepared from SPPEK-DMs exhibited ion exchange capacities (IEC) ranging from 0.93 mmolg-1 to 1.86 mmolg-1. Water uptake, swelling, oxidative stability and methanol permeability of SPPEKDMs membranes were investigated. SPPEK-DMs membranes exhibited high oxidative stability. The methanol permeability values of SPPEK-DMs membranes were in the range 5.15 10-8-6.61 10-7 cm2s-1, which was much lower than those of Nafion117. The proton conductivity of SPPEK-DM40 membranes was 1.1 10-2 Scm-1 at 70C.
2012, 30(4): 520-529
doi: 10.1007/s10118-012-1154-y
Abstract:
In this study, an application of artificial neural network (ANN) has been presented in modeling and studying the effect of compounding variables on abrasion behavior of rubber formulations. Three case studies were carried out in which the experiment data were collected according to classical response surface designs. Besides developing the ANN models, we developed response surface methodology (RSM) to confirm the ANN predictions. A simple relation was employed for determination of relative importance of each variable according to ANN models. It was shown through these case studies that ANN models delivered very good data fitting and their simulating curves could help the researchers to better understand the abrasion behavior.
In this study, an application of artificial neural network (ANN) has been presented in modeling and studying the effect of compounding variables on abrasion behavior of rubber formulations. Three case studies were carried out in which the experiment data were collected according to classical response surface designs. Besides developing the ANN models, we developed response surface methodology (RSM) to confirm the ANN predictions. A simple relation was employed for determination of relative importance of each variable according to ANN models. It was shown through these case studies that ANN models delivered very good data fitting and their simulating curves could help the researchers to better understand the abrasion behavior.
2012, 30(4): 530-536
doi: 10.1007/s10118-012-1151-1
Abstract:
Fumed silica/bisphenol A dicyanate ester (BADCy) nanocomposites were prepared by introducing different contents of nano-sized fumed SiO2 into the BADCy matrix. Two different average primary particle diameters of 12 and 40 nm were chosen. Dibutyltindilaurate (DBTDL) catalyst was chosen to catalyze the cyanate ester group into triazine group via cyclotrimerization reaction. The SEM micrographs indicated that the fumed SiO2 particles were homogeneously dispersed in the poly(bisphenol A dicyanate) matrix by means of ultrasonic treatment and the addition of a coupling agent. The FTIR spectroscopy shows that, not only DBTDL catalyzes the polymerization reaction but also ―OH groups of the SiO2 particles surface help the catalyst for the complete polymerization of BADCy monomer. The thermal stability of the cured BADCy can be improved by adequate addition of fumed SiO2. A slight increase in the dielectric constant and dielectric loss values were identified by testing the dielectric properties of the prepared nanocomposite samples. By increasing the SiO2 content, there was a slight increasing in the thermal conductivity values of the tested samples. The obtained results proved that the fumed silica/BADCy nanocomposites had good thermal and dielectrical properties and can be used in many applications such as in the thermal insulation field.
Fumed silica/bisphenol A dicyanate ester (BADCy) nanocomposites were prepared by introducing different contents of nano-sized fumed SiO2 into the BADCy matrix. Two different average primary particle diameters of 12 and 40 nm were chosen. Dibutyltindilaurate (DBTDL) catalyst was chosen to catalyze the cyanate ester group into triazine group via cyclotrimerization reaction. The SEM micrographs indicated that the fumed SiO2 particles were homogeneously dispersed in the poly(bisphenol A dicyanate) matrix by means of ultrasonic treatment and the addition of a coupling agent. The FTIR spectroscopy shows that, not only DBTDL catalyzes the polymerization reaction but also ―OH groups of the SiO2 particles surface help the catalyst for the complete polymerization of BADCy monomer. The thermal stability of the cured BADCy can be improved by adequate addition of fumed SiO2. A slight increase in the dielectric constant and dielectric loss values were identified by testing the dielectric properties of the prepared nanocomposite samples. By increasing the SiO2 content, there was a slight increasing in the thermal conductivity values of the tested samples. The obtained results proved that the fumed silica/BADCy nanocomposites had good thermal and dielectrical properties and can be used in many applications such as in the thermal insulation field.
2012, 30(4): 537-547
doi: 10.1007/s10118-012-1150-2
Abstract:
High quality free-standing poly(thiophene-3-acetic acid) (PTAA), a water-soluble polythiophene derivative, was successfully electrosynthesized in boron trifluoride diethyl etherate (BFEE) + 25% (by volume) trifluoroacetic acid (TFA) at lower potential (0.38 V versus Pt). The carboxyl group makes PTAA highly soluble in water, facilitating its potential application as a blue-light-emitting material. PTAA films with conductivity of 7 S cm-1 obtained from this medium showed better redox activity and thermal stability. The structure and morphology of the polymer were studied by UV-Vis, FT-IR, 1H-NMR spectra and scanning electron microscopy, respectively.
High quality free-standing poly(thiophene-3-acetic acid) (PTAA), a water-soluble polythiophene derivative, was successfully electrosynthesized in boron trifluoride diethyl etherate (BFEE) + 25% (by volume) trifluoroacetic acid (TFA) at lower potential (0.38 V versus Pt). The carboxyl group makes PTAA highly soluble in water, facilitating its potential application as a blue-light-emitting material. PTAA films with conductivity of 7 S cm-1 obtained from this medium showed better redox activity and thermal stability. The structure and morphology of the polymer were studied by UV-Vis, FT-IR, 1H-NMR spectra and scanning electron microscopy, respectively.
2012, 30(4): 548-560
doi: 10.1007/s10118-012-1146-y
Abstract:
Sulphonated polystyrene ethylene butylene polystyrene (SPSEBS) prepared with 35% sulphonation was found to be highly elastic and enlarged up to 300%-400% of its initial length. It absorbed over 110% of water by weight. A major drawback of this membrane is its poor mechanical properties which are not adequate for use as polymer electrolytes in fuel cells. To overcome this, SPSEBS was blended with poly(vinylidene fluoride) (PVDF), a hydrophobic polymer. The blend membranes showed better mechanical properties than the base polymer. The effect of PVDF content on water uptake, ion exchange capacity and proton conductivity of the blend membranes was investigated. This paper presents the results of recent studies applied to develop an optimized in-house membrane electrode assembly (MEA) preparation technique combining catalyst ink spraying and assembly hot pressing. Easy steps were chosen in this preparation technique in order to simplify the method, aiming at cost reduction. The open circuit voltage for the cell with SPSEBS is 0.980 V which is higher compared to that of the cell with Nafion 117 (0.790 V). From this study, it is concluded that a polymer electrolyte membrane suitable for proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) application can be obtained by blending SPSEBS and PVDF in appropriate proportions. The methanol permeability and selectivity showed a strong influence on DMFC performance.
Sulphonated polystyrene ethylene butylene polystyrene (SPSEBS) prepared with 35% sulphonation was found to be highly elastic and enlarged up to 300%-400% of its initial length. It absorbed over 110% of water by weight. A major drawback of this membrane is its poor mechanical properties which are not adequate for use as polymer electrolytes in fuel cells. To overcome this, SPSEBS was blended with poly(vinylidene fluoride) (PVDF), a hydrophobic polymer. The blend membranes showed better mechanical properties than the base polymer. The effect of PVDF content on water uptake, ion exchange capacity and proton conductivity of the blend membranes was investigated. This paper presents the results of recent studies applied to develop an optimized in-house membrane electrode assembly (MEA) preparation technique combining catalyst ink spraying and assembly hot pressing. Easy steps were chosen in this preparation technique in order to simplify the method, aiming at cost reduction. The open circuit voltage for the cell with SPSEBS is 0.980 V which is higher compared to that of the cell with Nafion 117 (0.790 V). From this study, it is concluded that a polymer electrolyte membrane suitable for proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) application can be obtained by blending SPSEBS and PVDF in appropriate proportions. The methanol permeability and selectivity showed a strong influence on DMFC performance.
2012, 30(4): 561-567
doi: 10.1007/s10118-012-1141-3
Abstract:
A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane (DMDS) as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.
A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane (DMDS) as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.
2012, 30(4): 568-577
doi: 10.1007/s10118-012-1153-z
Abstract:
Three well-defined diblock copolymers of poly(methyl methacrylate-b-methacrylic acid) (P(MMA-b-MAA)) were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid) (PMAA) chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that, the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery.
Three well-defined diblock copolymers of poly(methyl methacrylate-b-methacrylic acid) (P(MMA-b-MAA)) were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid) (PMAA) chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that, the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery.
2012, 30(4): 578-588
doi: 10.1007/s10118-012-1147-x
Abstract:
Novel copolymers based on acrylamide (AM) and complex pseudorotaxane monomer N-(3-vinylbenzyl)-1,4- diaminobutane dihydrochloride with cucurbit[6]uril (CB[6]) (3VBCB) were prepared via free-radical polymerization in aqueous solution, and characterized by 1H-NMR, FT-IR, elemental analysis and static light scattering. The compositions of the copolymers (PAM3VBCB) with pseudorotaxane units were determined by 1H-NMR and elemental analysis. Thermal properties of the copolymers were studied by TGA, and the effects of the copolymer concentration and pH on the average hydrodynamic radius (Rh) of the copolymer molecules were studied by dynamic light scattering (DLS). The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of the copolymers. TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB. DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration, and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6] dethreading from the side chains of PAM3VBCB. CB[6] threading and dethreading of PAM3VBCB could be controlled by addition of BaCl2 and Na2SO4.
Novel copolymers based on acrylamide (AM) and complex pseudorotaxane monomer N-(3-vinylbenzyl)-1,4- diaminobutane dihydrochloride with cucurbit[6]uril (CB[6]) (3VBCB) were prepared via free-radical polymerization in aqueous solution, and characterized by 1H-NMR, FT-IR, elemental analysis and static light scattering. The compositions of the copolymers (PAM3VBCB) with pseudorotaxane units were determined by 1H-NMR and elemental analysis. Thermal properties of the copolymers were studied by TGA, and the effects of the copolymer concentration and pH on the average hydrodynamic radius (Rh) of the copolymer molecules were studied by dynamic light scattering (DLS). The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of the copolymers. TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB. DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration, and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6] dethreading from the side chains of PAM3VBCB. CB[6] threading and dethreading of PAM3VBCB could be controlled by addition of BaCl2 and Na2SO4.
2012, 30(4): 589-594
doi: 10.1007/s10118-012-1157-8
Abstract:
A series of new silicon-containing poly(p-arylene vinylene)s (PAVs) with anthracene units in the main chain were synthesized by hydrosilylation reaction. The introduction of organosilicon units improved the solubility of the polymers, and the - conjugation of polymeric chains was interrupted. These polymers behaved as blue-green light emitters with their fluorescence maximum at 447-499 nm and quantum yields in the range of 0.28-0.30 in solution.
A series of new silicon-containing poly(p-arylene vinylene)s (PAVs) with anthracene units in the main chain were synthesized by hydrosilylation reaction. The introduction of organosilicon units improved the solubility of the polymers, and the - conjugation of polymeric chains was interrupted. These polymers behaved as blue-green light emitters with their fluorescence maximum at 447-499 nm and quantum yields in the range of 0.28-0.30 in solution.
2012, 30(4): 595-602
doi: 10.1007/s10118-012-1160-0
Abstract:
Soap-free hydrophilic-hydrophobic core-shell latex particles with high carboxyl content in the core of the particles were synthesized via the seeded emulsion polymerization using methyl methacrylate (MMA), butyl acrylate (BA), methacrylic acid (MAA), styrene (St) and ethylene glycol dimethacrylate (EGDMA) as monomers, and the influences of MMA content used in the core preparation on polymerization, particle size and morphology were investigated by transmission electron microscopy, dynamic light scattering and conductometric titration. The results showed that the seeded emulsion polymerization could be carried out smoothly using starved monomer feeding process when MAA content in the core preparation was equal to or less than 24 wt%, and the encapsulating efficiency of the hydrophilic P(MMA-BA-MAAEGDMA) core with the hydrophobic PSt shell decreased with the increase in MAA content. When an interlayer of P(MMAMAA- St) with moderate polarity was inserted between the P(MMA-BA-MAA-EGDMA) core and the PSt shell, well designed soap-free hydrophilic-hydrophobic core-shell latex particles with 24 wt% MAA content in the core preparation were obtained.
Soap-free hydrophilic-hydrophobic core-shell latex particles with high carboxyl content in the core of the particles were synthesized via the seeded emulsion polymerization using methyl methacrylate (MMA), butyl acrylate (BA), methacrylic acid (MAA), styrene (St) and ethylene glycol dimethacrylate (EGDMA) as monomers, and the influences of MMA content used in the core preparation on polymerization, particle size and morphology were investigated by transmission electron microscopy, dynamic light scattering and conductometric titration. The results showed that the seeded emulsion polymerization could be carried out smoothly using starved monomer feeding process when MAA content in the core preparation was equal to or less than 24 wt%, and the encapsulating efficiency of the hydrophilic P(MMA-BA-MAAEGDMA) core with the hydrophobic PSt shell decreased with the increase in MAA content. When an interlayer of P(MMAMAA- St) with moderate polarity was inserted between the P(MMA-BA-MAA-EGDMA) core and the PSt shell, well designed soap-free hydrophilic-hydrophobic core-shell latex particles with 24 wt% MAA content in the core preparation were obtained.
2012, 30(4): 603-612
doi: 10.1007/s10118-012-1159-6
Abstract:
The morphology and mechanical properties of poly(ethylene-octene) copolymers (POE) obtained by dynamic packing injection molding were investigated by mechanical tests, differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The mechanical tests found that only POE with low octene content and high molecular weight show apparent response for external shear field. Further investigation has been done by DSC, FT-IR, and SEM in order to make clear the reason of that phenomenon. Finally, the hypothetical mechanism of POE microstructure formation under shear field has been proposed. For POE with low octene content and high molecular weight, orientation degree and mechanical properties both increase substantially under shear field. For POE with low octene content and low molecular weight, orientation degree and crystallinity increase under shear field, but it is not dramatically benefit for the mechanical properties. For POE with high octene content and high molecular weight, the shear field has little effect on the morphology and mechanical properties.
The morphology and mechanical properties of poly(ethylene-octene) copolymers (POE) obtained by dynamic packing injection molding were investigated by mechanical tests, differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The mechanical tests found that only POE with low octene content and high molecular weight show apparent response for external shear field. Further investigation has been done by DSC, FT-IR, and SEM in order to make clear the reason of that phenomenon. Finally, the hypothetical mechanism of POE microstructure formation under shear field has been proposed. For POE with low octene content and high molecular weight, orientation degree and mechanical properties both increase substantially under shear field. For POE with low octene content and low molecular weight, orientation degree and crystallinity increase under shear field, but it is not dramatically benefit for the mechanical properties. For POE with high octene content and high molecular weight, the shear field has little effect on the morphology and mechanical properties.
