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1995 Volume 13 Issue 1
1995, 13(1): 1-6
Abstract:
A physical model of series of the conductivity on chain and the interchain conductivitybetween chains is proposed to explain enhanced conductivity of stretched conducting polymers.This model suggests that the enhanced conductivity for stretched conducting polymers might bedue to increasing of the interchain conductivity between chains along the elongation direction afterdrawing processes if the conductivity on chain is assumed much larger than that of the interchainconductivity between chains. According to this model,it is expected that the temperature dependence of conductivity measured by four-probe method for stretched conducting polymers is controlled by a variation of the interchain conductivity between chains with temperature,which can be used to explain that a metallic temperature dependence of conductivity for stretched conducting polymers is not observed although the conductivity along the elongation direction is enhanced by two or three orders of magnitude.
A physical model of series of the conductivity on chain and the interchain conductivitybetween chains is proposed to explain enhanced conductivity of stretched conducting polymers.This model suggests that the enhanced conductivity for stretched conducting polymers might bedue to increasing of the interchain conductivity between chains along the elongation direction afterdrawing processes if the conductivity on chain is assumed much larger than that of the interchainconductivity between chains. According to this model,it is expected that the temperature dependence of conductivity measured by four-probe method for stretched conducting polymers is controlled by a variation of the interchain conductivity between chains with temperature,which can be used to explain that a metallic temperature dependence of conductivity for stretched conducting polymers is not observed although the conductivity along the elongation direction is enhanced by two or three orders of magnitude.
1995, 13(1): 7-19
Abstract:
Microporous membranes of low-high density polyethylene and their blends were prepared bythermally-induced phase separation of polymer/long-aliphatic chain alcohol (diluent) mixtures.The microstructures of this particular membrane, which depends on the diluent properties,polymer concentration and cooling rate, were observed by scanning electron microscopy."Beehive-type,"leafy-like, and lacy porous structure morphologies can be formed,depending onthe blend composition and phase separation conditions, which were discussed by the polymer and diluent crystallization processes.
Microporous membranes of low-high density polyethylene and their blends were prepared bythermally-induced phase separation of polymer/long-aliphatic chain alcohol (diluent) mixtures.The microstructures of this particular membrane, which depends on the diluent properties,polymer concentration and cooling rate, were observed by scanning electron microscopy."Beehive-type,"leafy-like, and lacy porous structure morphologies can be formed,depending onthe blend composition and phase separation conditions, which were discussed by the polymer and diluent crystallization processes.
1995, 13(1): 20-27
Abstract:
By means of ultrasonic attenuation apparatus, the ultrasonic velocity and attenuation ofanhydride-cured epoxy resins (EP)/poly (ethylene oxide) (PEO) blends were measured on thebasis of pulse-echo method. It was found that the sonic velocity of the blends decreased as thetemperature increased, but attenuation coefficient increased and possessed a peak value. Largervelocity and smaller attenuation coefficient(α)can be obtained from perfect crosslinking networkstructures of pure DGEBA cured with phthalic anhydride(PA).As for cured DGEBA/PEO blend systems,sonic velocity decreased as a function of PEO concentration,but attenuation coefficient (α) increased.
By means of ultrasonic attenuation apparatus, the ultrasonic velocity and attenuation ofanhydride-cured epoxy resins (EP)/poly (ethylene oxide) (PEO) blends were measured on thebasis of pulse-echo method. It was found that the sonic velocity of the blends decreased as thetemperature increased, but attenuation coefficient increased and possessed a peak value. Largervelocity and smaller attenuation coefficient(α)can be obtained from perfect crosslinking networkstructures of pure DGEBA cured with phthalic anhydride(PA).As for cured DGEBA/PEO blend systems,sonic velocity decreased as a function of PEO concentration,but attenuation coefficient (α) increased.
1995, 13(1): 28-34
Abstract:
Chiral liquid crystalline polymers containing biphenylene and azobenzene as the mesogensand S(-)-2-methyl-1-butanol as the chiral end group were synthesized and characterized by DSC,POM and X-ray diffraction. These polymers show crystalline or glassy liquid crystalline phase atroom temperature. Most polymers show smectic A or highly ordered smectic phases abovemelting temperature.
Chiral liquid crystalline polymers containing biphenylene and azobenzene as the mesogensand S(-)-2-methyl-1-butanol as the chiral end group were synthesized and characterized by DSC,POM and X-ray diffraction. These polymers show crystalline or glassy liquid crystalline phase atroom temperature. Most polymers show smectic A or highly ordered smectic phases abovemelting temperature.
1995, 13(1): 35-40
Abstract:
A new cyclic monomer, 2-methyl-2-methoxycarbonyl-5-methylene-1,3-dioxolan-4-one,was synthesized successfully. The monomer and intermediate were characterized by 1H NMR, 13CNMR, INEPT(Intensive Nuclei Enhanced by Polarization Transfer) technique, IR and elementalanalysis. Anionic polymerization of the monomer was carried out in anhydrous THF at -70℃,and 9-fluorenyllithium was used as initiator. The polymer structure was determined by IR, NMRand elemental analysis. Molecular weight of the polymer was estimated by viscosity measurement in DMSO at 30℃.
A new cyclic monomer, 2-methyl-2-methoxycarbonyl-5-methylene-1,3-dioxolan-4-one,was synthesized successfully. The monomer and intermediate were characterized by 1H NMR, 13CNMR, INEPT(Intensive Nuclei Enhanced by Polarization Transfer) technique, IR and elementalanalysis. Anionic polymerization of the monomer was carried out in anhydrous THF at -70℃,and 9-fluorenyllithium was used as initiator. The polymer structure was determined by IR, NMRand elemental analysis. Molecular weight of the polymer was estimated by viscosity measurement in DMSO at 30℃.
1995, 13(1): 41-50
Abstract:
In this paper, highly active Ziegler-Natta catalysts of MgCl2 supported TiCl4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can be obtained.Plausible structure model and mechanism were proposed.
In this paper, highly active Ziegler-Natta catalysts of MgCl2 supported TiCl4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can be obtained.Plausible structure model and mechanism were proposed.
1995, 13(1): 51-58
Abstract:
Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalline behaviour has been characterized by differentialscanning calorimetry (DSC) and optical polarizing microscopy. Structural broadening bysubstitution of methoxy group in 2, 2" positions of the mesogenic core produce polymers withlower transition temperatures. Polymers synthesized from ortho and meta substituted phenylene diamine did not form a liquid crystal phase.
Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalline behaviour has been characterized by differentialscanning calorimetry (DSC) and optical polarizing microscopy. Structural broadening bysubstitution of methoxy group in 2, 2" positions of the mesogenic core produce polymers withlower transition temperatures. Polymers synthesized from ortho and meta substituted phenylene diamine did not form a liquid crystal phase.
1995, 13(1): 59-65
Abstract:
Factors affecting the gelation of resorcinol-formaldehyde systems have been examined overvariable ranges applicable to oilfield use. Gelation of resorcinol-formaldehyde (RF) system wassensitive to pH,salinity and hardness. Generally,this gel system could be used in fresh water orlow salinity brine at pH higher than about 9. The application would require careful monitoring ofinjection fluids to avoid premature gelation or prolonged shut-in times,especially under conditionsof low salinity and high pH. Salinity and hardness compatibilities of the system were improved by sulfomethylation of resorcinol.Aqueous sulfomethylated resorcinol formaldehyde (SMRF) system could be used in brine with higher salinity and hardness and at a wider pH range of 5-10.
Factors affecting the gelation of resorcinol-formaldehyde systems have been examined overvariable ranges applicable to oilfield use. Gelation of resorcinol-formaldehyde (RF) system wassensitive to pH,salinity and hardness. Generally,this gel system could be used in fresh water orlow salinity brine at pH higher than about 9. The application would require careful monitoring ofinjection fluids to avoid premature gelation or prolonged shut-in times,especially under conditionsof low salinity and high pH. Salinity and hardness compatibilities of the system were improved by sulfomethylation of resorcinol.Aqueous sulfomethylated resorcinol formaldehyde (SMRF) system could be used in brine with higher salinity and hardness and at a wider pH range of 5-10.
1995, 13(1): 66-73
Abstract:
In-situ gelation of aqueous sulfomethylated resorcinol formaldehyde (SMRF) system inBerea core has been investigated. Two sets of displacement experiments were conducted with thissystem (containing 5% NaCl, 0. 036% CaCl2. 2H2O). The brine permeabilities of the coreswere reduced significantly from about 600 to 0.1 md. The in-situ gelation in Berea core occurreda little bit earlier than gelation anticipated from bulk test in the experiments. The gel time waseasier to control at initial pH between 6 and 8. During injection of SMRF system,the apparent viscosity was less than 1 mPa·s at 41℃.
In-situ gelation of aqueous sulfomethylated resorcinol formaldehyde (SMRF) system inBerea core has been investigated. Two sets of displacement experiments were conducted with thissystem (containing 5% NaCl, 0. 036% CaCl2. 2H2O). The brine permeabilities of the coreswere reduced significantly from about 600 to 0.1 md. The in-situ gelation in Berea core occurreda little bit earlier than gelation anticipated from bulk test in the experiments. The gel time waseasier to control at initial pH between 6 and 8. During injection of SMRF system,the apparent viscosity was less than 1 mPa·s at 41℃.
1995, 13(1): 74-77
Abstract:
Photopolymerization of propargyl acetate (PAT) with Michler's ketone (MK) asphotoinitiator in benzene has been investigated for the first time. Some features of the PATphotopolymerization with MK as photoinitiator is described.
Photopolymerization of propargyl acetate (PAT) with Michler's ketone (MK) asphotoinitiator in benzene has been investigated for the first time. Some features of the PATphotopolymerization with MK as photoinitiator is described.
1995, 13(1): 78-83
Abstract:
Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the rrgenerated cellulose films.The films were completely biodegraded after being in soil for 100 days.The transmittance of the films derived from linter and reed in visible band range were 80-90%.
Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the rrgenerated cellulose films.The films were completely biodegraded after being in soil for 100 days.The transmittance of the films derived from linter and reed in visible band range were 80-90%.
1995, 13(1): 84-90
Abstract:
Polymeric Grignard Reagent (PGR) based on the chloromethylated poly(ST-co-DVB) resinhas been prepared by means of anthracene-magnesium complex in THF (Anth-Mg-THF), andpolymer matrix with long polymethylene spacer was synthesized via the coupling reaction betweenPGR and α, ω-dibromoalkanes. Based on the studies of factors affecting the coupling, such ascatalyst,reaction time,the length of spacer etc.,this paper offers the optimal reaction conditionsand three typical experiment procedures. The mechanism for the formation and coupling reaction of PGR are also discussed.
Polymeric Grignard Reagent (PGR) based on the chloromethylated poly(ST-co-DVB) resinhas been prepared by means of anthracene-magnesium complex in THF (Anth-Mg-THF), andpolymer matrix with long polymethylene spacer was synthesized via the coupling reaction betweenPGR and α, ω-dibromoalkanes. Based on the studies of factors affecting the coupling, such ascatalyst,reaction time,the length of spacer etc.,this paper offers the optimal reaction conditionsand three typical experiment procedures. The mechanism for the formation and coupling reaction of PGR are also discussed.
1995, 13(1): 91-96
Abstract:
The stereoregular polymerization of methyl methacrylate (MMA) have been investigatedwith chiral anionic complex initiator[FILi-(-)SP]in toluene, THF and toluene/THF [1/1(v/v)]. The tacticities of PMMAs obtained in the three solvents have been found to be mainly asyndiotactic triads(s-PMMA)with content of 72.3, 67.7 and 71.4%,respectively.
The stereoregular polymerization of methyl methacrylate (MMA) have been investigatedwith chiral anionic complex initiator[FILi-(-)SP]in toluene, THF and toluene/THF [1/1(v/v)]. The tacticities of PMMAs obtained in the three solvents have been found to be mainly asyndiotactic triads(s-PMMA)with content of 72.3, 67.7 and 71.4%,respectively.
