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1993 Volume 11 Issue 1
1993, 11(1): 1-7
Abstract:
External magnetic field increases the photo-induced polymerization rate of styrene microemulsion.The type of photoinitiator plays an important role. The photoinitiators, used are dimethoxyphenyl acetophenone(DMPA), 1-hydroxycyclohexyl phenylketone (Irgacure 184) and dimethylhydroxyacetophenone (Darocur 1173). No magnetic effect was observed by using dibenzylketone (DBK) as photoinitiator. The molecular weight of the polymer is slightly affected by magnetic field. The influence of temperature has also been investigated.
External magnetic field increases the photo-induced polymerization rate of styrene microemulsion.The type of photoinitiator plays an important role. The photoinitiators, used are dimethoxyphenyl acetophenone(DMPA), 1-hydroxycyclohexyl phenylketone (Irgacure 184) and dimethylhydroxyacetophenone (Darocur 1173). No magnetic effect was observed by using dibenzylketone (DBK) as photoinitiator. The molecular weight of the polymer is slightly affected by magnetic field. The influence of temperature has also been investigated.
1993, 11(1): 8-15
Abstract:
The preparation of conducting PPQ film was first reported in the previous paper. It is very interesting that this film is highly sensitive to moisture in air. The hydration and dehydration of the film are accompanied by change not only in color but also in conductivity and UV-visible spectrum. The conducting PPQ is reduced to PPQ and loses its conductivity after being soaked in water.
The preparation of conducting PPQ film was first reported in the previous paper. It is very interesting that this film is highly sensitive to moisture in air. The hydration and dehydration of the film are accompanied by change not only in color but also in conductivity and UV-visible spectrum. The conducting PPQ is reduced to PPQ and loses its conductivity after being soaked in water.
1993, 11(1): 16-21
Abstract:
The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15—20% PPS into nylon-6 has provided UL V-0 rating for the system and there is enhancement in tensile and flexural properties. The results obtained on the thermal, crystallization and flow characteristics of the nylon-PPS system upto a loading of 40% PPS are also discussed.
The present paper deals with the use of a new polymeric flame retardant material, polyphenylene sulphide (PPS) for plastics. Incorporation of 15—20% PPS into nylon-6 has provided UL V-0 rating for the system and there is enhancement in tensile and flexural properties. The results obtained on the thermal, crystallization and flow characteristics of the nylon-PPS system upto a loading of 40% PPS are also discussed.
1993, 11(1): 22-25
Abstract:
Silica-bound 15-Crown-5, 18-Crown-6 with a spacer of propyloxymethyl and their platinum complexes have been synthesized. It was found that they were efficient catalysts for the hydrosilylation of olefms with triethoxysilane in the temperature range of 60 to 130 ℃.
Silica-bound 15-Crown-5, 18-Crown-6 with a spacer of propyloxymethyl and their platinum complexes have been synthesized. It was found that they were efficient catalysts for the hydrosilylation of olefms with triethoxysilane in the temperature range of 60 to 130 ℃.
1993, 11(1): 26-30
Abstract:
α,α-dimethoxy-α-Phenyl acetophenone (DMPA) is an efficient and thermally stable photoinitiator. Here its spectral characteristics in the transient state were shown. The transient species were identified as a benzoyl radical and a dimethoxyi benzyl radical that played a primary initiation role in polymerization. The kinetics and mechanism of the bulk polymerization of MMA were investigated. The exponent of DMPA concentration and kp/k11/2 value were found to be 0.5 and 0.066 mol(-1/2)l1/2s-1/2, respectively.The existence of oxygen led to obtain the polymer with higher molecular weight,which can be attributed to the occurrence of the subsequent polymerization induced by active polymer end group.In the photocrosslinking reaction,the dependence of DMP A content on initial rate has been found.A principal reason is that the sample contained higher percentage of DMPA has higher light-absorbed efficiency.In solid film,higher concentration of DMP A is permitted to be used because there is little excited state self-quenching effect in the rigid medium.
α,α-dimethoxy-α-Phenyl acetophenone (DMPA) is an efficient and thermally stable photoinitiator. Here its spectral characteristics in the transient state were shown. The transient species were identified as a benzoyl radical and a dimethoxyi benzyl radical that played a primary initiation role in polymerization. The kinetics and mechanism of the bulk polymerization of MMA were investigated. The exponent of DMPA concentration and kp/k11/2 value were found to be 0.5 and 0.066 mol(-1/2)l1/2s-1/2, respectively.The existence of oxygen led to obtain the polymer with higher molecular weight,which can be attributed to the occurrence of the subsequent polymerization induced by active polymer end group.In the photocrosslinking reaction,the dependence of DMP A content on initial rate has been found.A principal reason is that the sample contained higher percentage of DMPA has higher light-absorbed efficiency.In solid film,higher concentration of DMP A is permitted to be used because there is little excited state self-quenching effect in the rigid medium.
1993, 11(1): 31-37
Abstract:
The effects of interfacial modifier on the mechanical properties of kaolin-filled polyamide 6 (PA6) have been studied. The interracial interaction between polyamide 6 and kaolin has been character ized by means of infrared spectroscopy (IR) and scanning electron microscopy (SEM). The results show that the role of the interracial modifier lies in forming an elastic interlayer with good adhesion between kaolin and PA 6. A composite with high impact strength, high tensile strength and high elastic modulus can be obtained by inserting the elastic interfacial modiffer into the rigid-particle-filled polymer system.
The effects of interfacial modifier on the mechanical properties of kaolin-filled polyamide 6 (PA6) have been studied. The interracial interaction between polyamide 6 and kaolin has been character ized by means of infrared spectroscopy (IR) and scanning electron microscopy (SEM). The results show that the role of the interracial modifier lies in forming an elastic interlayer with good adhesion between kaolin and PA 6. A composite with high impact strength, high tensile strength and high elastic modulus can be obtained by inserting the elastic interfacial modiffer into the rigid-particle-filled polymer system.
1993, 11(1): 38-45
Abstract:
The copolymerization of p-diethynylbenzene (PDEB) with phenylacetylene (PhA), 4, 4'-diethynylbiphenyl (DEBP)or m-diethynylbenzene (MDEB) are studied by varying mole ratios of monomers. When the mole ratios of PDEB/PhA are less or equal to 1/5, the copolymers are soluble and fusible, but the other copolymers are insoluble and infusible. The results show that the good solvent of cross-linked copolymers is benzene and their solubility parameter is 9.15 cal0.5.cm(-1.5). And their swellability (θp), Huggins parameter(x),density (d254)and the average molecular weights between crosslinks(Mc)are measured.It is found that θp and Mc of copolymers are greater but d254 is less than that of respective homopolymers.IR spectra show that the copolymers have transoid configuration and small number of unreacted ethynyl groups exist in the copolymers.The mechanism about the polymerization or acetylenic derivatives initiated by (Ph3P)2PdCl2 is discussed.
The copolymerization of p-diethynylbenzene (PDEB) with phenylacetylene (PhA), 4, 4'-diethynylbiphenyl (DEBP)or m-diethynylbenzene (MDEB) are studied by varying mole ratios of monomers. When the mole ratios of PDEB/PhA are less or equal to 1/5, the copolymers are soluble and fusible, but the other copolymers are insoluble and infusible. The results show that the good solvent of cross-linked copolymers is benzene and their solubility parameter is 9.15 cal0.5.cm(-1.5). And their swellability (θp), Huggins parameter(x),density (d254)and the average molecular weights between crosslinks(Mc)are measured.It is found that θp and Mc of copolymers are greater but d254 is less than that of respective homopolymers.IR spectra show that the copolymers have transoid configuration and small number of unreacted ethynyl groups exist in the copolymers.The mechanism about the polymerization or acetylenic derivatives initiated by (Ph3P)2PdCl2 is discussed.
1993, 11(1): 46-53
Abstract:
Polyamide-1010 samples were irradiated in vacuum at room temperature by Cobalt-60 γ-rays. The free radicals formed in irradiation were studied by means of electron spin resonance (ESR)techniques.The ESRspectra consisted of a quartet and a superimposed singlet which were attributed to radical -CO-NH-CH-CH2 and -CH2-C=O, respectively. The effects of temperature and crystaUinity on the radicals were discussed and the mechanism for the production and decay of the radicals was also proposed.
Polyamide-1010 samples were irradiated in vacuum at room temperature by Cobalt-60 γ-rays. The free radicals formed in irradiation were studied by means of electron spin resonance (ESR)techniques.The ESRspectra consisted of a quartet and a superimposed singlet which were attributed to radical -CO-NH-CH-CH2 and -CH2-C=O, respectively. The effects of temperature and crystaUinity on the radicals were discussed and the mechanism for the production and decay of the radicals was also proposed.
1993, 11(1): 54-58
Abstract:
A new type of crown functionalized polysiloxane, in which the crown moieties were incorporated into main chain, and its platinum complex were synthesized. The polysiloxane was synthesized from 3, 16-dihydroxy-1- thia - 5, 8, 11, 14- tetraoxacycloheptadecane via etheritication with ω-chloroundecene, followed by hydrosilylation with triethoxysilane, cohydrolysis with D4, sequentially. Treating the polysiloxane with potassium cholroplatinite, the title complex was obtained. It was found that the platinum complex exhibited high catalytic activity in the hydrosilylation of olefins with triethoxysilane.
A new type of crown functionalized polysiloxane, in which the crown moieties were incorporated into main chain, and its platinum complex were synthesized. The polysiloxane was synthesized from 3, 16-dihydroxy-1- thia - 5, 8, 11, 14- tetraoxacycloheptadecane via etheritication with ω-chloroundecene, followed by hydrosilylation with triethoxysilane, cohydrolysis with D4, sequentially. Treating the polysiloxane with potassium cholroplatinite, the title complex was obtained. It was found that the platinum complex exhibited high catalytic activity in the hydrosilylation of olefins with triethoxysilane.
1993, 11(1): 59-66
Abstract:
An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using 'h:anning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the coupling agents to the PA6/ kaolin (20 wt percent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover,the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/P A6 systems.The rheological behavior of KH550 kaolin/PA6 system is different from that of KH560 kaolin/PA6 system,although chemical reactions have taken palce between the surface of KH 550 kaolin(or KH560 kaolin)and PA6 matrix during melt processing.This is attributable,in part,to the differences in the state of dispersion of kaolins in PA6 matrix and,to a great extent,to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.
An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using 'h:anning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the coupling agents to the PA6/ kaolin (20 wt percent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover,the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/P A6 systems.The rheological behavior of KH550 kaolin/PA6 system is different from that of KH560 kaolin/PA6 system,although chemical reactions have taken palce between the surface of KH 550 kaolin(or KH560 kaolin)and PA6 matrix during melt processing.This is attributable,in part,to the differences in the state of dispersion of kaolins in PA6 matrix and,to a great extent,to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.
1993, 11(1): 67-75
Abstract:
Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR,1H-NMR and GPC.Various experimental parameters controlling the copolymerization were studied in detail.The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers.A detailed "comb-model" was proposed to describe the molecular structure of the graft copolymers.Finally,this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.
Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called "selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR,1H-NMR and GPC.Various experimental parameters controlling the copolymerization were studied in detail.The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers.A detailed "comb-model" was proposed to describe the molecular structure of the graft copolymers.Finally,this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.
1993, 11(1): 76-83
Abstract:
A drawn high density polyethylene(HDPE)has been measured by Raman spectroscopy and differential scanning calorimetry (DSC). The crystalline structure of drawn HDPE is analysed by the Raman internal modes in terms of mass fractions of the crystalline orthorhombic phase, the liquid- like amorphous phase and the disordered anisotropic phase. The mass fractions depend on draw temperature Td and draw ratio Rd. The fraction of disordered anisotropic amorphous phase changes very little with, the Tdand increases with increasing Rd.Sum of the mass fractions of crystalline orthorhombic phase and the disordered anisotropic phase increases linearly as the same slope as the crystallinity Wc determined from DSC measurements with increasing Td or Rd and it is higher than the Wc for all the samples.The results show that the mass fraction of disordered anisotropic phase is partially devoted by the taut tie molecules(TTMs) in the amorphous state.The dependence of the disordered anisotropic phase on Td and Rd supports the mechanism of plastic deformation of fibre structure.
A drawn high density polyethylene(HDPE)has been measured by Raman spectroscopy and differential scanning calorimetry (DSC). The crystalline structure of drawn HDPE is analysed by the Raman internal modes in terms of mass fractions of the crystalline orthorhombic phase, the liquid- like amorphous phase and the disordered anisotropic phase. The mass fractions depend on draw temperature Td and draw ratio Rd. The fraction of disordered anisotropic amorphous phase changes very little with, the Tdand increases with increasing Rd.Sum of the mass fractions of crystalline orthorhombic phase and the disordered anisotropic phase increases linearly as the same slope as the crystallinity Wc determined from DSC measurements with increasing Td or Rd and it is higher than the Wc for all the samples.The results show that the mass fraction of disordered anisotropic phase is partially devoted by the taut tie molecules(TTMs) in the amorphous state.The dependence of the disordered anisotropic phase on Td and Rd supports the mechanism of plastic deformation of fibre structure.
1993, 11(1): 84-91
Abstract:
The compatibility and dynamics of latex bidirectional/nterpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to, a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side-groups of PBA in the LBIPN are longer than those in the LIPN.The relation between the 13C linewidths of PBA and temperature is also discussed.
The compatibility and dynamics of latex bidirectional/nterpenetrating polymer networks (LBIPNs) and latex IPN(LIPN) of poly(vinyl acetate)(PVAc) and poly (butyl acrylate )(PBA) are investigated by means of dynamic mechanical spectroscopy (DMS) and nuclear magnetic resonance (NMR) techniques. The results of DMS show that the compatibility of the LBIPNs is much better than that of the corresponding LIPN and depends to, a large extent on the distribution of PVAc both in the core and in the shell. The results of NMR measurements indicate that the rotational correlation times of the side-groups of PBA in the LBIPN are longer than those in the LIPN.The relation between the 13C linewidths of PBA and temperature is also discussed.
1993, 11(1): 92-96
Abstract:
The temperature spectra of internal friction of polyetheretherketone (PEEK) are investigated from 130K to 250K with a multi-function torsion pendulum in the frequency range of 0.1 Hz to 5 Hz. A relaxation process, γ relaxation, appears in the temperature range of the measurement. Its relaxation time distribution in terms of a Gaussian distribution, and the relation between molecular motion mechanism and the distribution characteristic are discussed. The element process of γ relaxation is found to be a disordering one.
The temperature spectra of internal friction of polyetheretherketone (PEEK) are investigated from 130K to 250K with a multi-function torsion pendulum in the frequency range of 0.1 Hz to 5 Hz. A relaxation process, γ relaxation, appears in the temperature range of the measurement. Its relaxation time distribution in terms of a Gaussian distribution, and the relation between molecular motion mechanism and the distribution characteristic are discussed. The element process of γ relaxation is found to be a disordering one.
