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2014 Volume 32 Issue 3
2014, 32(3): 255-267
doi: 10.1007/s10118-014-1411-3
Abstract:
The effect of silica nanoparticles on the morphology of (10/90 wt%) PDMS/PBD blends during the shear induced coalescence of droplets of the minor phase at low shear rate was investigated systematically in situ by using an optical shear technique. Two blending procedures were used: silica nanoparticles were introduced to the blends by pre-blending silica particles first in PDMS dispersed phase (procedure 1) or in PBD matrix phase (procedure 2). Bimodal or unimodal droplet size distributions were observed for the filled blends during coalescence, which depend not so much on the surface characteristics of silica but mainly on blending procedure. For pure (10/90 wt%) PDMS/PBD blend, the droplet size distribution exhibits bimodality during the early coalescence. When silica nanoparticles (hydrophobic and hydrophilic) were added to the blends with procedure 1, bimodal droplet size distributions disappear and unimodal droplet size distributions can be maintained during coalescence; the shape of the different peaks is invariably Gaussian. Simultaneously, coalescence of the PDMS droplets was suppressed efficiently by the silica nanoparticles. It was proposed that with this blending procedure the nanoparticles should be mainly kinetically trapped at the interface or in the PDMS dispersed phase, which provides an efficient steric barrier against coalescence of the PDMS dispersed phase. However, bimodal droplet size distributions in the early stage of coalescence still occur when incorporating silica nanoparticles into the blends with procedure 2, and then coalescence of the PDMS droplets cannot be suppressed efficiently by the silica nanoparticles. It was proposed that with this blending protocol the nanoparticles should be mainly located in the PBD matrix phase, which leads to an inefficient steric barrier against coalescence of the PDMS dispersed phase; thus the morphology evolution in these filled blends is similar to that in pure blend and bimodal droplet size distributions can be observed during the early coalescence. These results imply that exploiting non-equilibrium processes by varying preparation protocol may provide an elegant route to regulate the temporal morphology of the filled blends during coalescence.
The effect of silica nanoparticles on the morphology of (10/90 wt%) PDMS/PBD blends during the shear induced coalescence of droplets of the minor phase at low shear rate was investigated systematically in situ by using an optical shear technique. Two blending procedures were used: silica nanoparticles were introduced to the blends by pre-blending silica particles first in PDMS dispersed phase (procedure 1) or in PBD matrix phase (procedure 2). Bimodal or unimodal droplet size distributions were observed for the filled blends during coalescence, which depend not so much on the surface characteristics of silica but mainly on blending procedure. For pure (10/90 wt%) PDMS/PBD blend, the droplet size distribution exhibits bimodality during the early coalescence. When silica nanoparticles (hydrophobic and hydrophilic) were added to the blends with procedure 1, bimodal droplet size distributions disappear and unimodal droplet size distributions can be maintained during coalescence; the shape of the different peaks is invariably Gaussian. Simultaneously, coalescence of the PDMS droplets was suppressed efficiently by the silica nanoparticles. It was proposed that with this blending procedure the nanoparticles should be mainly kinetically trapped at the interface or in the PDMS dispersed phase, which provides an efficient steric barrier against coalescence of the PDMS dispersed phase. However, bimodal droplet size distributions in the early stage of coalescence still occur when incorporating silica nanoparticles into the blends with procedure 2, and then coalescence of the PDMS droplets cannot be suppressed efficiently by the silica nanoparticles. It was proposed that with this blending protocol the nanoparticles should be mainly located in the PBD matrix phase, which leads to an inefficient steric barrier against coalescence of the PDMS dispersed phase; thus the morphology evolution in these filled blends is similar to that in pure blend and bimodal droplet size distributions can be observed during the early coalescence. These results imply that exploiting non-equilibrium processes by varying preparation protocol may provide an elegant route to regulate the temporal morphology of the filled blends during coalescence.
2014, 32(3): 268-279
doi: 10.1007/s10118-014-1403-3
Abstract:
Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution (DS) on properties of films. Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene (LDPE). Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS (2.5, 1.7) maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 ℃ and 389 ℃ which were higher than the decomposition temperature of native starch film (349 ℃). Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films (4.18% and 3.76%, respectively) was lower than that of native starch films (5%). This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.
Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution (DS) on properties of films. Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene (LDPE). Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS (2.5, 1.7) maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 ℃ and 389 ℃ which were higher than the decomposition temperature of native starch film (349 ℃). Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films (4.18% and 3.76%, respectively) was lower than that of native starch films (5%). This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.
2014, 32(3): 280-291
doi: 10.1007/s10118-014-1406-0
Abstract:
2-Acryloxyacetophenone (AAP) was prepared and subjected to suspension polymerization with methyl methacrylate (MMA) using azobisisobutyronitrile (AIBN) as free radical initiator. The differently sulfonated AAP-MMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70℃. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity (IEC), thermo gravimetric analysis (TGA), particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol (ATL) loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid (SGF) than in stimulated intestinal fluids (SIF). The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.
2-Acryloxyacetophenone (AAP) was prepared and subjected to suspension polymerization with methyl methacrylate (MMA) using azobisisobutyronitrile (AIBN) as free radical initiator. The differently sulfonated AAP-MMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70℃. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity (IEC), thermo gravimetric analysis (TGA), particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol (ATL) loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid (SGF) than in stimulated intestinal fluids (SIF). The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.
2014, 32(3): 292-304
doi: 10.1007/s10118-014-1407-z
Abstract:
Highly refractive and transparent polyamides containing thiadiazole units have been developed. These polymers were prepared by a polycondensation reaction of 4,4'-(1,3,4-thiadiazole-2,5-thio) bis(methylene) dibenzoyl chloride (TDTBM-DC) and diamine which contained thioether (―S―) and sulfone units. They showed good thermal stabilities such as a relatively high glass transition temperature of 206-233 ℃and a 5% weight-loss temperature (T5%) of 376-395℃. The optical transmittance of the polymer at 450 nm is higher than 83%. The heterocycle units and plural ―S― linkages provide the polymer with a high refractive index of 1.716-1.725 at 633 nm and a low birefringence of 0.003-0.004. Also they showed improved solubility in polar aprotic solvents and could form moderate strength films with tensile strength of 72.8-83.1 MPa and storage modulus of 1.0-1.8 GPa (at 200℃).
Highly refractive and transparent polyamides containing thiadiazole units have been developed. These polymers were prepared by a polycondensation reaction of 4,4'-(1,3,4-thiadiazole-2,5-thio) bis(methylene) dibenzoyl chloride (TDTBM-DC) and diamine which contained thioether (―S―) and sulfone units. They showed good thermal stabilities such as a relatively high glass transition temperature of 206-233 ℃and a 5% weight-loss temperature (T5%) of 376-395℃. The optical transmittance of the polymer at 450 nm is higher than 83%. The heterocycle units and plural ―S― linkages provide the polymer with a high refractive index of 1.716-1.725 at 633 nm and a low birefringence of 0.003-0.004. Also they showed improved solubility in polar aprotic solvents and could form moderate strength films with tensile strength of 72.8-83.1 MPa and storage modulus of 1.0-1.8 GPa (at 200℃).
2014, 32(3): 305-314
doi: 10.1007/s10118-014-1408-y
Abstract:
A novel intumescent flame retardant coating, consisting of poly(vinylphosphonic acid) (PVPA) as the acid source and branched polyethylenimine (BPEI) as the blowing agent, was constructed on the surface of ramie fabrics by alternate assembly to remarkably improve the flame retardancy of ramie. The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie. Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600℃, while the control (uncoated) fabric left less than 1.4 wt% residue. Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time, and the residues well preserved the original weave structure and fiber morphology, whereas, the uncoated fabric left only ashes. Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%, relative to those of the uncoated fabric.
A novel intumescent flame retardant coating, consisting of poly(vinylphosphonic acid) (PVPA) as the acid source and branched polyethylenimine (BPEI) as the blowing agent, was constructed on the surface of ramie fabrics by alternate assembly to remarkably improve the flame retardancy of ramie. The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie. Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600℃, while the control (uncoated) fabric left less than 1.4 wt% residue. Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time, and the residues well preserved the original weave structure and fiber morphology, whereas, the uncoated fabric left only ashes. Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%, relative to those of the uncoated fabric.
2014, 32(3): 315-320
doi: 10.1007/s10118-014-1401-5
Abstract:
Functional polymers such as polyethylene grafted glycidyl methacrylate (PE-g-GMA) and ethylene-methyl acrylate-glycidyl methacrylate terpolymer (E/MA/GMA) were used as compatibilizers in the preparation of highly filled composites of polyethylene/magnesium hydroxide(PE/MH). Comparative studies were performed on the effect of magnesium hydroxide and stearic acid on the interface within polymer and magnesium hydroxide composites. The effect of polymeric compatibilizers on the properties of the composites was studied using tensile and impact tests, torque rheological analysis, differential scanning calorimetry and environmental scanning electron microscopy (ESEM). The microstructure of highly filled PE/MH composites changed after the addition of functional polymers. The mechanical properties of the composite material increased after compatibilization. The compatibilization processes of PE-g-GMA and E/MA/GMA were different. The grafted polymer was more compatible with polyethylene, which led to a polar polymer phase. In contrast, the tercopolymer tended to adhere to the surface of MH particles.
Functional polymers such as polyethylene grafted glycidyl methacrylate (PE-g-GMA) and ethylene-methyl acrylate-glycidyl methacrylate terpolymer (E/MA/GMA) were used as compatibilizers in the preparation of highly filled composites of polyethylene/magnesium hydroxide(PE/MH). Comparative studies were performed on the effect of magnesium hydroxide and stearic acid on the interface within polymer and magnesium hydroxide composites. The effect of polymeric compatibilizers on the properties of the composites was studied using tensile and impact tests, torque rheological analysis, differential scanning calorimetry and environmental scanning electron microscopy (ESEM). The microstructure of highly filled PE/MH composites changed after the addition of functional polymers. The mechanical properties of the composite material increased after compatibilization. The compatibilization processes of PE-g-GMA and E/MA/GMA were different. The grafted polymer was more compatible with polyethylene, which led to a polar polymer phase. In contrast, the tercopolymer tended to adhere to the surface of MH particles.
2014, 32(3): 321-332
doi: 10.1007/s10118-014-1399-8
Abstract:
Antibody targeted delivery is an effective strategy to improve the diagnostic imaging outcome of nanoscale imaging agents in the focal areas. Dual targeting micelles encapsulating superparamagnetic iron oxide were prepared from the amphiphilic block copolymer poly(ethylene glycol)-poly(-caprolactone) (PEG-b-PCL) with different targeting ligands cRGD and scFv-ErbB single chain antibody conjugated to the distal ends of PEG block. The breast cancer animal model was established by subcutaneous injecting the BT474 cells into the BALB/c-nu female nude mice and then employed to assess the potential of the dual ligand targeted magnetic micelles as a novel MRI contrast agent on a 1.5 T clinical MRI scanner. The T2 signal intensity of the tumor in animals receiving the dual ligand targeted magnetic micelles via tail vein decreased more significantly than the single ligand targeted and nontargeted magnetic micelles. These results indicate that the dual ligand targeted magnetic micelles, cRGD/scFv-ErbB-PEG-PCL-SPION, have great potential to act as a new type of effective nanoscale MRI contrast agent for early diagnosis of breast cancer.
Antibody targeted delivery is an effective strategy to improve the diagnostic imaging outcome of nanoscale imaging agents in the focal areas. Dual targeting micelles encapsulating superparamagnetic iron oxide were prepared from the amphiphilic block copolymer poly(ethylene glycol)-poly(-caprolactone) (PEG-b-PCL) with different targeting ligands cRGD and scFv-ErbB single chain antibody conjugated to the distal ends of PEG block. The breast cancer animal model was established by subcutaneous injecting the BT474 cells into the BALB/c-nu female nude mice and then employed to assess the potential of the dual ligand targeted magnetic micelles as a novel MRI contrast agent on a 1.5 T clinical MRI scanner. The T2 signal intensity of the tumor in animals receiving the dual ligand targeted magnetic micelles via tail vein decreased more significantly than the single ligand targeted and nontargeted magnetic micelles. These results indicate that the dual ligand targeted magnetic micelles, cRGD/scFv-ErbB-PEG-PCL-SPION, have great potential to act as a new type of effective nanoscale MRI contrast agent for early diagnosis of breast cancer.
2014, 32(3): 333-349
doi: 10.1007/s10118-014-1404-2
Abstract:
Effects of branches on the crystallization kinetics of polypropylene-g-polystyrene (PP-g-PS) and polypropylene-g-poly(n-butyl acrylate) (PP-g-PnBA) graft copolymers with well-defined molecular structures were systematically investigated by DSC. The Avrami equation was used to analyze the isothermal crystallization process, while the analysis of nonisothermal crystallization process was based on the Jeziorny-modified Avrami model and Mo model. The kinetics results of isothermal and nonisothermal crystallization verified the peculiar effects of branches on the crystallization process of PP backbones in PP-g-PS and PP-g-PnBA graft copolymers: on one hand, the interaction between branches (- interaction between PS branches, or dipole-dipole interaction between PnBA branches) restrained the mobility and reptation ability of the PP backbones, which hindered the crystallization process; on the other hand, the heterogeneous nucleation effect resulting from the branched structure and fluctuation-assisted nucleation mechanism (caused by microphase separation between the PS or PnBA rich phase and the PP rich phase) became more pronounced with increasing branch length, which facilitated the crystallization process.
Effects of branches on the crystallization kinetics of polypropylene-g-polystyrene (PP-g-PS) and polypropylene-g-poly(n-butyl acrylate) (PP-g-PnBA) graft copolymers with well-defined molecular structures were systematically investigated by DSC. The Avrami equation was used to analyze the isothermal crystallization process, while the analysis of nonisothermal crystallization process was based on the Jeziorny-modified Avrami model and Mo model. The kinetics results of isothermal and nonisothermal crystallization verified the peculiar effects of branches on the crystallization process of PP backbones in PP-g-PS and PP-g-PnBA graft copolymers: on one hand, the interaction between branches (- interaction between PS branches, or dipole-dipole interaction between PnBA branches) restrained the mobility and reptation ability of the PP backbones, which hindered the crystallization process; on the other hand, the heterogeneous nucleation effect resulting from the branched structure and fluctuation-assisted nucleation mechanism (caused by microphase separation between the PS or PnBA rich phase and the PP rich phase) became more pronounced with increasing branch length, which facilitated the crystallization process.
2014, 32(3): 350-361
doi: 10.1007/s10118-014-1405-1
Abstract:
We have experimentally studied the growth process of a water-absorbing polymer commonly known as hydro-gel. We took a number of spherical beads, immersed them in pure water, measured their diameters at regular intervals of time and plotted graphs showing the change in volume with the time of immersion, to analyze their swelling properties. We have formulated a dynamical model on the basis of curve-fitting to our experimental data. Our mathematical modelling is devoted solely towards the explanation of the swelling of spherical hydro-gels and we have interpreted our observations on these basis. And finally evaluating the constants of the process, we have shown that the results obtained from our modelling and numerical simulation exactly match the experimental data. The justification of this new approach lies in its successful application for the complete explanation of our observations through numerical and analytical ways.
We have experimentally studied the growth process of a water-absorbing polymer commonly known as hydro-gel. We took a number of spherical beads, immersed them in pure water, measured their diameters at regular intervals of time and plotted graphs showing the change in volume with the time of immersion, to analyze their swelling properties. We have formulated a dynamical model on the basis of curve-fitting to our experimental data. Our mathematical modelling is devoted solely towards the explanation of the swelling of spherical hydro-gels and we have interpreted our observations on these basis. And finally evaluating the constants of the process, we have shown that the results obtained from our modelling and numerical simulation exactly match the experimental data. The justification of this new approach lies in its successful application for the complete explanation of our observations through numerical and analytical ways.
2014, 32(3): 362-370
doi: 10.1007/s10118-014-1412-2
Abstract:
The stereo-defects distribution of polypropylene of the two industry biaxially oriented polypropylene (BOPP) samples T28FE and F28SO with different processing properties was studied through successive self-nucleation and annealing (SSA) technique. It was found that there were more medium isotactic components in sample F28SO, and the isotactic sequence length of polypropylene of sample F28SO was shorter and the isotactic sequence length distribution of polypropylene of sample F28SO was broader, which could be processed well at high-speed orientation during the processing of BOPP films. This result indicates that the isotactic sequence length distribution of polypropylene is related to the processing speed during preparing BOPP films, and the stereo-defects distribution of polypropylene has an important influence on its processing ability.
The stereo-defects distribution of polypropylene of the two industry biaxially oriented polypropylene (BOPP) samples T28FE and F28SO with different processing properties was studied through successive self-nucleation and annealing (SSA) technique. It was found that there were more medium isotactic components in sample F28SO, and the isotactic sequence length of polypropylene of sample F28SO was shorter and the isotactic sequence length distribution of polypropylene of sample F28SO was broader, which could be processed well at high-speed orientation during the processing of BOPP films. This result indicates that the isotactic sequence length distribution of polypropylene is related to the processing speed during preparing BOPP films, and the stereo-defects distribution of polypropylene has an important influence on its processing ability.
2014, 32(3): 371-376
doi: 10.1007/s10118-014-1389-x
Abstract:
Novel conjugated polymers with aza-15-crown-5 as pendant groups, P1 were synthesized by the Sonogashira coupling reaction. The polymer P1 was found to show fluorescence enhancement response towards Ba2+. The gradual recovery and turning-point of emission intensity of polymers appeared in the addition of Ba2+, which provided good evidence for the fluorescence amplification mechanism of conjugated polymers.
Novel conjugated polymers with aza-15-crown-5 as pendant groups, P1 were synthesized by the Sonogashira coupling reaction. The polymer P1 was found to show fluorescence enhancement response towards Ba2+. The gradual recovery and turning-point of emission intensity of polymers appeared in the addition of Ba2+, which provided good evidence for the fluorescence amplification mechanism of conjugated polymers.
2014, 32(3): 377-384
doi: 10.1007/s10118-014-1374-4
Abstract:
A low operating pressure nanofiltration membrane is prepared by interfacial polymerization between m-phenylenediamine (MPDA) and trimesoyl chloride (TMC) using PVC hollow fiber membrane as supporting. A series of PVC nanofiltration membranes with different molecular weight cutoff (MWCO) can be obtained by controlling preparation conditions. Chemical and morphological characterization of the membrane surface was carried out by FTIR-ATR and SEM. MWCO was characterized by filtration experiments. The preparation conditions were investigated in detail. At the optimized conditions (40 min air-dried time, aqueous phase containing 0.5% MPDA, 0.05% SDS and 0.6% acid absorbent, oil phase containing 0.3% TMC, and 1 min reaction time), under 0.3 MPa, water flux of the gained nanofiltration membrane reaches 17.8 L/m2h, and the rejection rates of methyl orange and MgSO4 are more than 90% and 60%, respectively.
A low operating pressure nanofiltration membrane is prepared by interfacial polymerization between m-phenylenediamine (MPDA) and trimesoyl chloride (TMC) using PVC hollow fiber membrane as supporting. A series of PVC nanofiltration membranes with different molecular weight cutoff (MWCO) can be obtained by controlling preparation conditions. Chemical and morphological characterization of the membrane surface was carried out by FTIR-ATR and SEM. MWCO was characterized by filtration experiments. The preparation conditions were investigated in detail. At the optimized conditions (40 min air-dried time, aqueous phase containing 0.5% MPDA, 0.05% SDS and 0.6% acid absorbent, oil phase containing 0.3% TMC, and 1 min reaction time), under 0.3 MPa, water flux of the gained nanofiltration membrane reaches 17.8 L/m2h, and the rejection rates of methyl orange and MgSO4 are more than 90% and 60%, respectively.
