Login In
1985 Volume 3 Issue 3
1985, 3(3): 185-193
Abstract:
The reaction of pyrylium salt with primary amine has been utilized to synthesize 4,4'-bipyri-dinium salts and pyridinium polymers. Seven new 4,4'-(1,4-phenylene-) bis-[N-alkyl(aryl)-2,6-diphenyl-] pyridinium perchlorates 4 and five corresponding bipyridinium polymers 5 were preparedwith good yields from 4,4'-(1,4-phenylene-) bis-(2,6-diphenyl-) pyrylium perchlorate 3. Preliminarytests have been made for their redox behavior and catalytic activity.
The reaction of pyrylium salt with primary amine has been utilized to synthesize 4,4'-bipyri-dinium salts and pyridinium polymers. Seven new 4,4'-(1,4-phenylene-) bis-[N-alkyl(aryl)-2,6-diphenyl-] pyridinium perchlorates 4 and five corresponding bipyridinium polymers 5 were preparedwith good yields from 4,4'-(1,4-phenylene-) bis-(2,6-diphenyl-) pyrylium perchlorate 3. Preliminarytests have been made for their redox behavior and catalytic activity.
1985, 3(3): 194-203
Abstract:
The drawing behavior of three types of PET spherulites and PET amorphous samples have beenstudied. Two different sample preparation techniques were used in this study: (1) The films withnormal positive, normal negative or abnormal spherulites were prepared by solution casting tech-niques, then the films were deformed by uniaxial drawing. The uniaxial drawing behavior of PETspherulites appears to be dependent on the angles between the c-axis and the radius direction of the spherulites and that the deformation of spherulites becomes more difficult the larger the angles. (2)Amorphous films of PET were prepared first,then the films were deformed under uniaxial drawing to achieve c-axis orientation at a temperature near the glass transition temperature.The oriented films were subsequently annealed with fixed length at 215℃.The films prepared in this way exhibit excellent c-axis orientation along the stretching direction.The degree of perfection of the crystalline structure is much greater than that of the spherulites.
The drawing behavior of three types of PET spherulites and PET amorphous samples have beenstudied. Two different sample preparation techniques were used in this study: (1) The films withnormal positive, normal negative or abnormal spherulites were prepared by solution casting tech-niques, then the films were deformed by uniaxial drawing. The uniaxial drawing behavior of PETspherulites appears to be dependent on the angles between the c-axis and the radius direction of the spherulites and that the deformation of spherulites becomes more difficult the larger the angles. (2)Amorphous films of PET were prepared first,then the films were deformed under uniaxial drawing to achieve c-axis orientation at a temperature near the glass transition temperature.The oriented films were subsequently annealed with fixed length at 215℃.The films prepared in this way exhibit excellent c-axis orientation along the stretching direction.The degree of perfection of the crystalline structure is much greater than that of the spherulites.
1985, 3(3): 204-215
Abstract:
Polymorphous i-PP containing a and β phases were studied by WAXD and computer peak-resolution method (CPRM). The asymmetric Gaussian-Cauchy functions (a-GC) were adoptedto fit the profiles of both amorphous and crystalline peaks. For the crystalline peaks, the fitting resultsof a-GC are better than the symmetric-GC; for the amorphous peaks, they are better than polynomialand exponential functions, etc. Using the retarded least-square procedure (RLSP) on microcom-puter the results of peak-resolution are rather satisfatory.For the polymorphous samples containing αand β phases,the relations between phase-state,crystallinity,crystalline size,the ratio of α,β relative content and the crystallization temperature Tc were studied by CPRM.The ratio of α,β relative contents obtained by CPRM and Turner-Jones eq have been carefully compared.There are many improvements in this work.A simple estimation method of WAXD peak areas,both for amorphous and crystalline peaks,is suggested.
Polymorphous i-PP containing a and β phases were studied by WAXD and computer peak-resolution method (CPRM). The asymmetric Gaussian-Cauchy functions (a-GC) were adoptedto fit the profiles of both amorphous and crystalline peaks. For the crystalline peaks, the fitting resultsof a-GC are better than the symmetric-GC; for the amorphous peaks, they are better than polynomialand exponential functions, etc. Using the retarded least-square procedure (RLSP) on microcom-puter the results of peak-resolution are rather satisfatory.For the polymorphous samples containing αand β phases,the relations between phase-state,crystallinity,crystalline size,the ratio of α,β relative content and the crystallization temperature Tc were studied by CPRM.The ratio of α,β relative contents obtained by CPRM and Turner-Jones eq have been carefully compared.There are many improvements in this work.A simple estimation method of WAXD peak areas,both for amorphous and crystalline peaks,is suggested.
1985, 3(3): 216-225
Abstract:
Blending isotactic polypropylene (PP) with ethylene-propylene terpolymer (EPT) is one of thesimplest and most effective ways for toughening PP. In order to further improve the toughness ofPP/EPT blend and to enhance the stability of the dispersed rubber phase, a diblock copolymer com-posed of PP and ethylene-propylene rubber blocks (PP-EPR) was added into the blend, as it is con-sidered that "forced compatibility" of the two components will be effected through the two chemi-cally bonded blocks, while two-phase structure still remains.Experimental results indicate that PP-EPR is an effective compatibilizer for PP/EPT blend.It not only increases the toughness of the blend,but also decreases the loss of tensile strengths usually accompanying the toughening of plastics with an elastomer,which is very well explained by the mor-phological structure changes when an appropriate amount of PP-EPR was added into the blend.
Blending isotactic polypropylene (PP) with ethylene-propylene terpolymer (EPT) is one of thesimplest and most effective ways for toughening PP. In order to further improve the toughness ofPP/EPT blend and to enhance the stability of the dispersed rubber phase, a diblock copolymer com-posed of PP and ethylene-propylene rubber blocks (PP-EPR) was added into the blend, as it is con-sidered that "forced compatibility" of the two components will be effected through the two chemi-cally bonded blocks, while two-phase structure still remains.Experimental results indicate that PP-EPR is an effective compatibilizer for PP/EPT blend.It not only increases the toughness of the blend,but also decreases the loss of tensile strengths usually accompanying the toughening of plastics with an elastomer,which is very well explained by the mor-phological structure changes when an appropriate amount of PP-EPR was added into the blend.
1985, 3(3): 226-234
Abstract:
The polymerization rates of fourteen aromatic and heterocyclic dinitriles were measured by infraredspectroscopy and compared with that of 4, 4′-biphenyldicarbonitrile. The rate is greatly enhancedwhen an electron withdrawing group is substituted at the para position of cyano group in aromaticdinitriles. The polymerization rates of heterocyclic dinitriles wer discussed in terms of π-lectrondensity of the heterocyclic rings.
The polymerization rates of fourteen aromatic and heterocyclic dinitriles were measured by infraredspectroscopy and compared with that of 4, 4′-biphenyldicarbonitrile. The rate is greatly enhancedwhen an electron withdrawing group is substituted at the para position of cyano group in aromaticdinitriles. The polymerization rates of heterocyclic dinitriles wer discussed in terms of π-lectrondensity of the heterocyclic rings.
1985, 3(3): 234-243
Abstract:
Irradiation crosslinking of semi-crystalline polyamides was performed by high energy electronswith various dosages. It is known that the melting behavior of the polymers after irradiation is acomplex phenomenon. In company with the wide angle X-ray diffraction and DSC data of irradiatedand unirradiated polyamides it is possible to develop the local order and perfection of the crystallinitiesslightly which resulted from introduction of intermolecular crosslinking in amorphous region, incl-uding in amorphous-crystalline interface and crystalline defect regions due to irradiation.It can be explained that slight increase of melting temperature(Tm) and heat of fusion(△Hf) with increasing dosage for both of higher crystallinity nylon 4 and nylon 6.For irradiated lower crystallinity nylons,in contrast,the Tm and △Hf decrease obviously with increasing dosage.In this case,radiation cross-linking"freeze in" the pre-existing morphology,and then the prevention for reorganization during heating is a dominant effect.The Tm from the second melting for all of the samples were depressed,corresponding with Flory theory.Therefore the crosslinks imposed on the molecules restrained the molecular mobility,and that not only depresses the crystallinity but also increases the imperfection of crystallites when the radiated polymer melted and then recrystallized.These are also reflected in the depression of heat and entropy of fusion as well as the appearance of double melting peaks on the DSC thermograms.
Irradiation crosslinking of semi-crystalline polyamides was performed by high energy electronswith various dosages. It is known that the melting behavior of the polymers after irradiation is acomplex phenomenon. In company with the wide angle X-ray diffraction and DSC data of irradiatedand unirradiated polyamides it is possible to develop the local order and perfection of the crystallinitiesslightly which resulted from introduction of intermolecular crosslinking in amorphous region, incl-uding in amorphous-crystalline interface and crystalline defect regions due to irradiation.It can be explained that slight increase of melting temperature(Tm) and heat of fusion(△Hf) with increasing dosage for both of higher crystallinity nylon 4 and nylon 6.For irradiated lower crystallinity nylons,in contrast,the Tm and △Hf decrease obviously with increasing dosage.In this case,radiation cross-linking"freeze in" the pre-existing morphology,and then the prevention for reorganization during heating is a dominant effect.The Tm from the second melting for all of the samples were depressed,corresponding with Flory theory.Therefore the crosslinks imposed on the molecules restrained the molecular mobility,and that not only depresses the crystallinity but also increases the imperfection of crystallites when the radiated polymer melted and then recrystallized.These are also reflected in the depression of heat and entropy of fusion as well as the appearance of double melting peaks on the DSC thermograms.
1985, 3(3): 244-249
Abstract:
The 13C-NMR spectra of alternating copolymers of conjugated dienes, butadiene (BD), isoprene(IP) and chloroprene (CP), with methyl acrylate (MA) were studied. It is proved that they are allalternating copolymers. The BD units in Poly (BD-alt-MA) are joined to MA mainly in the form of trans 1,4-structure. The contents of trans 1,4-, cis 1,4-and 1,2-structure are 88, 7 and 5%, res-pectively. The IP and CP units in Poly(IP-alt-MA) and Poly(CP-alt-MA) exist essentially as trans1,4-configuration and connect with MA units in "head to head"arrangement predominantly,while CP-CP units present in Poly(CP-alt-MA) in a small quantity.
The 13C-NMR spectra of alternating copolymers of conjugated dienes, butadiene (BD), isoprene(IP) and chloroprene (CP), with methyl acrylate (MA) were studied. It is proved that they are allalternating copolymers. The BD units in Poly (BD-alt-MA) are joined to MA mainly in the form of trans 1,4-structure. The contents of trans 1,4-, cis 1,4-and 1,2-structure are 88, 7 and 5%, res-pectively. The IP and CP units in Poly(IP-alt-MA) and Poly(CP-alt-MA) exist essentially as trans1,4-configuration and connect with MA units in "head to head"arrangement predominantly,while CP-CP units present in Poly(CP-alt-MA) in a small quantity.
1985, 3(3): 250-257
Abstract:
A series of copolyesters were prepared from chloro-hydroquinone or methyl-hydroquinone,terephthalic acid, and two kinds of comonomers, such as oxy-4,4'-diphenol and isophthalic acid.which could provide kinking and bending in chain. The four-components copolyesters in certain range of compositions have low melting point,ssteady mesophase in a broad temperature range and fiber- forming tendency. This report focuses on the relations of their molecular composition-transitions- liquid crystallinityand fiber-forming tendency,and the morphologic characterizations of mesophase.
A series of copolyesters were prepared from chloro-hydroquinone or methyl-hydroquinone,terephthalic acid, and two kinds of comonomers, such as oxy-4,4'-diphenol and isophthalic acid.which could provide kinking and bending in chain. The four-components copolyesters in certain range of compositions have low melting point,ssteady mesophase in a broad temperature range and fiber- forming tendency. This report focuses on the relations of their molecular composition-transitions- liquid crystallinityand fiber-forming tendency,and the morphologic characterizations of mesophase.
1985, 3(3): 258-264
Abstract:
The charge-accumulating process of polymeric photoconductive coating film used in electro-photography as well as factors controlling the charging rate have been studied, and the characteriza-tion of charging process and kinetic equation have been established.
The charge-accumulating process of polymeric photoconductive coating film used in electro-photography as well as factors controlling the charging rate have been studied, and the characteriza-tion of charging process and kinetic equation have been established.
1985, 3(3): 265-271
Abstract:
The Thermal Field-Flow Fractionation (TFFF) method was used to determine the elution volumeof a series of star branched polystyrene having different number of arms but the same arm molecularweigh and polystyrene standards with narrow distribution whose molecular weight ranged from5.0×104 to 8.6×105. Results were obtained by measuring at two temperature difference (△T=30℃and △T=50℃ in THF. The same star branched samples were measured by means of GPC method.Comparison of Vr-M relationships obtained from TFFF and GPC showed that the displacement of Vr-M curves for star and linear polystyrene is larger than that in GPC.This difference is caused by the entirely different mechanism of separation for these two methods.As the controlling factor is hydrodynamic volume of the polymer chain in solution for GPC,it is the diffusion coefficient of polymer molecules for TFFF.The experimental results indicate that the influence of variance of chain structure on diffusion coefficient is stronger than that on the hydrodynamic volume and that TFFF tech-nique may be used as a method for characterizing branching of polymer molecules.For this purpose a proper theoretical model and more accurate experiments are needed.
The Thermal Field-Flow Fractionation (TFFF) method was used to determine the elution volumeof a series of star branched polystyrene having different number of arms but the same arm molecularweigh and polystyrene standards with narrow distribution whose molecular weight ranged from5.0×104 to 8.6×105. Results were obtained by measuring at two temperature difference (△T=30℃and △T=50℃ in THF. The same star branched samples were measured by means of GPC method.Comparison of Vr-M relationships obtained from TFFF and GPC showed that the displacement of Vr-M curves for star and linear polystyrene is larger than that in GPC.This difference is caused by the entirely different mechanism of separation for these two methods.As the controlling factor is hydrodynamic volume of the polymer chain in solution for GPC,it is the diffusion coefficient of polymer molecules for TFFF.The experimental results indicate that the influence of variance of chain structure on diffusion coefficient is stronger than that on the hydrodynamic volume and that TFFF tech-nique may be used as a method for characterizing branching of polymer molecules.For this purpose a proper theoretical model and more accurate experiments are needed.
1985, 3(3): 272-279
Abstract:
The photopolymerization of acrylonitrile and methyl methacrylate initiated by condensed aro-matic hydrocarbon-aniline systenis was studied at 25℃ under irradiation of 365 nm wavelengthlight. From kinetic data the monomer exponent has been measured to be 1.1. Within the concen-tration of 10-4—10-3M, the aromatic hydrocarbon exponents changrd from 0.30 to 0.40, depedingon the values of molar extinction coefficient of the hydrocarbons at 365 nm (ε365). The greater theε365, the Iower the exponents.The aniline exponents were measured to be in the range of 0.30—0.45.The aromatic hydrocarbon-aniline systems with the lower aniline exponent showed a lower ratio of the fluorescence quenching of the hydrocarbon by aniline and by the monomer.
The photopolymerization of acrylonitrile and methyl methacrylate initiated by condensed aro-matic hydrocarbon-aniline systenis was studied at 25℃ under irradiation of 365 nm wavelengthlight. From kinetic data the monomer exponent has been measured to be 1.1. Within the concen-tration of 10-4—10-3M, the aromatic hydrocarbon exponents changrd from 0.30 to 0.40, depedingon the values of molar extinction coefficient of the hydrocarbons at 365 nm (ε365). The greater theε365, the Iower the exponents.The aniline exponents were measured to be in the range of 0.30—0.45.The aromatic hydrocarbon-aniline systems with the lower aniline exponent showed a lower ratio of the fluorescence quenching of the hydrocarbon by aniline and by the monomer.
1985, 3(3): 280-288
Abstract:
The crystallization process of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)and PEO/poly(vinyl acetate) (PVAc) blends has been characterized by Fourier Transform Infrared(FTIR) spectra in conjunction with Differential Scanning Calorimeter (DSC) measurements. Thecrystallinity of PEO varies consistently with PEO content in PEO/PVAc blends and the PEO/PMMAblends containing 50 wt% or less PMMA. For the PEO/PMMA blends containing 60 wt% or more PMMA, the crystallinity of PEO decreases more than PEO content but develops with crystallization time.These results can be explained in terms of difference betweeen the crystallization temperature(Tc) and glass transition temperature(Tg) of the blends as a function of content of amorphous component.
The crystallization process of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)and PEO/poly(vinyl acetate) (PVAc) blends has been characterized by Fourier Transform Infrared(FTIR) spectra in conjunction with Differential Scanning Calorimeter (DSC) measurements. Thecrystallinity of PEO varies consistently with PEO content in PEO/PVAc blends and the PEO/PMMAblends containing 50 wt% or less PMMA. For the PEO/PMMA blends containing 60 wt% or more PMMA, the crystallinity of PEO decreases more than PEO content but develops with crystallization time.These results can be explained in terms of difference betweeen the crystallization temperature(Tc) and glass transition temperature(Tg) of the blends as a function of content of amorphous component.
1985, 3(3): 289-299
Abstract:
Melt blends of poly(ethylene oxide) (PEO) and poly(vinyl acetate (PVAc) were prepared andstudied by Torsional Pendulum Analysis (TPA) and Fourier Transform Infrared (FTIR). Two glasstransitions were found in these blends. The lower Tg corresponds to the segmental motion in thepure PEO. The dependence of the position and broadness of the higher Tg on composition of theblends indicates that the two components are compatible in the amorphous phase with micro-hetero-geneity. These Tg values observed from mixed PVAc/PEO phase are much higher than that calculated from Fox equation.The comparison of the blends quenched and annealed from melt implies that PVAc mixed with PEO at the segmental level on molten state and the deviation of Tg values from Fox equation could be due to variation of the blend's composition by crustallization of part of the PEO component.Further indication that the blends are compatible down to the level of chain segments and that there are specific interactions between PVAc and PEO molecules comes from the analysis of FTIR spectra of the blends and the solution of PVAc in diethylene glycol dimethyl ether.
Melt blends of poly(ethylene oxide) (PEO) and poly(vinyl acetate (PVAc) were prepared andstudied by Torsional Pendulum Analysis (TPA) and Fourier Transform Infrared (FTIR). Two glasstransitions were found in these blends. The lower Tg corresponds to the segmental motion in thepure PEO. The dependence of the position and broadness of the higher Tg on composition of theblends indicates that the two components are compatible in the amorphous phase with micro-hetero-geneity. These Tg values observed from mixed PVAc/PEO phase are much higher than that calculated from Fox equation.The comparison of the blends quenched and annealed from melt implies that PVAc mixed with PEO at the segmental level on molten state and the deviation of Tg values from Fox equation could be due to variation of the blend's composition by crustallization of part of the PEO component.Further indication that the blends are compatible down to the level of chain segments and that there are specific interactions between PVAc and PEO molecules comes from the analysis of FTIR spectra of the blends and the solution of PVAc in diethylene glycol dimethyl ether.
1985, 3(3): 300-304
Abstract:
The epoxy resin modified by liquid chloroprene-hydroxyethylmethacrylate copolymer (CP-HEMA) is a new kind of structural adhesives with good mechanical properties. By changing its mole-cular structure, it may also have such desirable properties as retardation of combustion, enduringweather aging, inert oils and chemicals. A series of the thermosets of the epoxy resin modifiedby CP-HEMA used as a toughener were prepared. The effects of CP-HEMA content, catalyst con-tent and curing temperature on the mechanical on the mechanical properties of modified epoxy resin system were studied.The thermal weight-loss curves were examined.The two-phase morphology was observed and discussed.
The epoxy resin modified by liquid chloroprene-hydroxyethylmethacrylate copolymer (CP-HEMA) is a new kind of structural adhesives with good mechanical properties. By changing its mole-cular structure, it may also have such desirable properties as retardation of combustion, enduringweather aging, inert oils and chemicals. A series of the thermosets of the epoxy resin modifiedby CP-HEMA used as a toughener were prepared. The effects of CP-HEMA content, catalyst con-tent and curing temperature on the mechanical on the mechanical properties of modified epoxy resin system were studied.The thermal weight-loss curves were examined.The two-phase morphology was observed and discussed.
