共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Enomoto 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1255-1267
Polymerization of vinyl chloride (VC) was studied. natural evolution of HCl from VC occurred in the polymerization. VC, VC-αd1, VC-β,βd2 and VC-d3 were used to study the reactivities of the hydrogen atoms in the polymerization and the β-hydrogen atoms contributed to the chain transfer. Chemical and physical methods were used to observe irregular structures, such as branching, double bonds, and head-to-head or tail-to-tail addition, and also to confirm the relation between conversion and the irregular structures. 相似文献
2.
V. Jíov J. Jan
a M. Kolínský 《Journal of polymer science. Part A, Polymer chemistry》1977,15(3):533-536
A sample of high molecular weight poly(vinyl chloride) (PVC) was fractionated by classical precipitation fractionation and gel-permeation chromatography (GPC) on a preparative scale. The fractions thus obtained were characterized by light scattering, viscometry, and by the GPC method. The measured weight-average molecular weights M?w, intrinsic viscosity [η], and polydispersity index M?w/M?n values were used for the determination of the Mark-Houwink equation, [η] = KMa, for PVC in cyclohexanone (CHX) at 25°C valid for molecular weights from 100,000 to 625,000. 相似文献
3.
Rudolph D. Deanin Roger E. Somers 《Journal of polymer science. Part A, Polymer chemistry》1970,8(8):1949-1954
The processability of rigid poly(vinyl chloride) can be improved by adding trichloroethylene as chain-transfer agent, increasing the polymerization temperature, and especially by combining the two effects together. The resulting synergistic interaction is best expressed by an equation of the form, P = (A + B[TCE])eC/T, where P is thermal plasticity, AeC/T is the combined effect of chain transfer to initiator and monomer and termination through combination and disproportionation, and B[TCE]eC/T represents the chain-transfer action of trichloroethylene. 相似文献
4.
A study has been made on the suspension polymerization of vinyl chloride in the presence of epoxidized cottonseed oil. Inclusion of the additive into the polymer chain was proved by i.r. spectrophotometry. The effects of epoxidized cottonseed oil on polymerization rate and K-value were slight, but plasticizer absorption by the polymer was reduced. Thermogravimetric curves of the product have been obtained, and show that epoxidized cottonseed oil improves the thermostability of the polymer. 相似文献
5.
M. Kudrna V. Jíov M. Kolínský 《Journal of polymer science. Part A, Polymer chemistry》1977,15(10):2367-2372
The flow behavior of 10, 15, and 25% solutions of high molecular weight, thermally stable poly(vinyl chloride) in cyclohexanone was studied in the temperature range 50–140°C with respect to fiber-forming properties. The flow behavior of such solutions at shear rates ranging from 1–103 sec?1 is pronouncedly non-Newtonian with the exception of the 10% solution at 70°C. It can be adequately described by known empirical linear relationships. The apparent viscosities and activation energies are considerably higher than those for the usual types of poly(vinyl chloride), but vary within limits acceptable for the preparation and spinning of solutions. 相似文献
6.
Wassaburo Kawai Taichi Ichihashi 《Journal of polymer science. Part A, Polymer chemistry》1972,10(6):1709-1718
The system comprising the ethoxydized product of triethylaluminum, cuprous chloride, and carbon tetrachloride was used as an initiator for polymerization of vinyl chloride, and the polymerization kinetics was studied. From plots of the molar number of number-average polymer chain Y/P? versus yield Y, the two parameters a ( = ∫ Ridt ? 1/2 ∫ Rtdt) and b ( = ∫ Rtrdt/∫ Rpdt) were estimated to be 6 × 10?3 mole/l. and 6.6 × 10?4 respectively. Studies of the tacticity of the poly(vinyl chloride) showed isotactic = 49.3% and syndiotactic = 50.7%. The present initiator also permitted copolymerization of vinyl chloride with carbon monoxide; the monomer reactivity ratios were r1 = 0.40 (vinyl chloride) and r2 = 0.01 (carbon monoxide). 相似文献
7.
Akira Akimoto Toshir
Yoshida 《Journal of polymer science. Part A, Polymer chemistry》1972,10(4):993-1000
Polymerization of vinyl chloride by the ternary catalyst system of VOCl3–AIRnCl3–n complexing agent was investigated. It was suggested that the formation of a polar complex (or charge-transfer complex) between AlRnCl3–n and the complexing agent participated in the polymerization of vinyl chloride. In the copolymerization of vinyl chloride with propylene with the present catalyst system, it was more difficult to incorporate the propylene unit in the copolymer than with a typical radical catalyst. 相似文献
8.
Zbigniew Florjanczyk Marek Siudakiewicz 《Journal of polymer science. Part A, Polymer chemistry》1986,24(8):1849-1862
The free-radical polymerization of methyl methacrylate (MMA) initiated by systems comprizing benzoyl peroxide (BPO) and different organoaluminium compounds (OACs) has been studied. The influence of the type of OAC, concentration of components of the initiation system, temperature, and time on the reaction yield have been determined. Systems containing BPO and diethylaluminium chloride (Et2AlCl) have been found to enable us to obtain, in high yields at room temperature, of homopolymers of MMA, methyl acrylate, acrylonitrile (AN), vinyl acetate, and the alternating AN/styrene (St) copolymer; they are, however, not very active in the homopolymerization of St and vinyl chloride. Factors affecting the polymerization yield have been discussed in terms of the mechanism of the reaction between BPO and OACs, reactivity of alkyl radicals formed in these systems, and catalytic effect of OAC in the propagation step. 相似文献
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10.
Koichiro Arita V. Stannett 《Journal of polymer science. Part A, Polymer chemistry》1973,11(7):1565-1588
The kinetics of bulk and precipitation polymerization of vinyl chloride has been studied over wide range of reaction temperature by using γ-ray induced initiation. The autoacceleration effect, which has been observed by many investigators in the case of chemically initiated bulk polymerization of vinyl chloride above 40°C and has been the most controversial aspect of the bulk polymerization of vinyl chloride, was found to disappear in the bulk polymerization below 0°C. In the bulk polymerization at 40°C, the autoacceleration effect was observed up to 20%, in agreement with the results of previous investigators, and a pronounced effect of the size of polymer particles on the time–conversion curve was observed. The kinetics of precipitation polymerization of vinyl chloride in the presence of some nonsolvents was successfully described by a oneparameter equation. A kinetic scheme, which clearly explains the zero-order reaction behavior of bulk polymerization at low temperature and the kinetic behavior of precipitation polymerization described by the empirical equation, is proposed. The autoacceleration effect in the bulk polymerization at 40°C was considered to be essentially the same phenomenon as the small retardation period observed in the bulk polymerization at low temperature. 相似文献
11.
Tadashi Narita Hiroshi Hamana Fumiaki Sekiya Yasuyuki Nojima 《Journal of polymer science. Part A, Polymer chemistry》2007,45(5):908-910
To report a new polymerization reaction phenomenon, this article examines the polymerization of butyl vinyl ether and N‐vinylcarbazole in the presence of 2‐benzoxypentafluoropropene [CF2?C(CF3)OCOC6H5 or BPFP]. The homopolymer of butyl vinyl ether was produced in the presence of a catalytic amount of BPFP in high yields. N‐Vinylcarbazole, which is a monomer well‐known for producing its homopolymer under cationic polymerization conditions, also yielded its homopolymer in the presence of BPFP. It was concluded that some cationic species would be yielded by the addition of BPFP. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 908–910, 2007. 相似文献
12.
V. V. Korshak A. M. Polyakova V. F. Mironov A. D. Petrov 《Russian Chemical Bulletin》1959,8(1):169-171
Summary The free-radical polymerization of some unsaturated compounds of Group IV elements was investigated. The tendency for these compounds to polymerize falls in the order Si > C > Ge > Sn. 相似文献
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14.
Conclusions The systems Fe(CO)5 + hexamethylphosphotriamide and Fe(CO)5 + DMF are efficient initiators for the telomerization of vinyl chloride by benzyl chloride involving the C-Cl bond of the benzyl chloride, in which connection both the conversion of the telogen and yield of telomers is high. Telomers of general formula C6H5CH2-(CH2CHCl)nCl (n=1–3) were isolated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2541–2546, November, 1980. 相似文献
15.
Zbigniew Florjanczyk Witold Kuran Jadwiga Sitkowska Andrzej Zikowski 《Journal of polymer science. Part A, Polymer chemistry》1987,25(1):343-351
Polymerization of vinyl chloride in the presence of systems containing a transition metal compound/Lewis base and an organoaluminum compound of a different length of carbon chain have been carried out. The influence of the structure and the concentrations of particular components on the polymerization yield and molecular weight of the products has been determined. The polymerization of vinyl chloride proceeds according to the free radical mechanism, and the effectiveness of such types of initiators decreases with an increase in the length of the substituent chain in the organoaluminum chain. When using ethyl derivatives, the maximum degree of vinyl chloride conversion is about 75%, and for polystyryl or polyisoprenylaluminum of an average polymerization degree of 50–100, the conversion did not exceed 0.5%. The maximum polymerization degree of vinyl chloride in block copolymers containing polyisoprenyl or polystyryl units was 90–300. 相似文献
16.
Yuji Minoura Hiroyuki Toshima 《Journal of polymer science. Part A, Polymer chemistry》1972,10(4):1109-1122
It was found that styrene was polymerized with chlorosilane compounds and metal halides in 1,2-dichloroethane. The rate of polymerization of styrene was proportional to the concentration of styrene, trimethylchlorosilane, and mercuric chloride. The overall activation energy of polymerization was ?2.9 kcal/mole. The polymer yield decreased markedly on addition of ether into the polymerization system, and the infrared spectrum showed evidence of silicone fragments in the polymer. From the results, it was considered that the polymerization was initiated by a siliconium cation. The formation of a complex between trimethylchlorosilane and metal halides (i.e., ferric chloride) was confirmed by the continuous variation method of ultraviolet and visible absorption spectra. 相似文献
17.
A. V. Yurkovetskii G. N. Bondarenko V. D. Oppengeim K. L. Makovetskii 《Russian Chemical Bulletin》1988,37(9):1785-1788
Conclusions 1,3-Dimethylenecyclobutane and 1-methyl-3-methylenecyclobutene are metallated in the presence of THF by alkyllithium compounds under mild conditions with the formation of one and the same organolithium compound of the -pentadienyl type. Under the same conditions, 1,2-dimethylenecyclobutane adds alkyllithium compounds, to form a -alkenyl complex.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1996–1999, September, 1988.The authors wish to express their gratitude to E. R. Dolinskaya and her fellow workers for recording the spectra on the Bruker HX-270 spectrometer. 相似文献
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19.
Poly(vinyl chloride) (PVC) was prepared using a titanium complex with an anionic oxygen tripod ligand [CpCo{P(O)(OEt)2}3]− () as catalyst and methyl aluminoxane (MAO) as cocatalyst. The polymerization behavior was compared with that of pentamethyl cyclopentadienyl titanium trichloride (Me5CpTiCl3). It is observed that LOEtTiCl3 can polymerize vinyl chloride with activity comparable to that of Me5CpTiCl3. The PVC samples prepared with LOEtTiCl3/MAO exhibit bimodal molecular weight distribution and the fraction of high molecular weight peak decreases with polymerization temperature. The microstructure and thermal decomposition of the PVC obtained were studied. Five types of structural defect were detected by 1H-NMR. Only saturated structural defects are found at low polymerization temperature, but at high polymerization temperature unsaturated structural defects, possibly resulting from dehydrochlorination of the saturated structural defects, appear as well. No head-to-head structural defect is observed. 13C-NMR shows that the PVC prepared by LOEtTiCl3 has an atactic stereostructure. Compared with the PVC from radical polymerization and anionic polymerization, the PVC samples prepared with LOEtTiCl3 show improved thermal stability. 相似文献
20.
Koichiro Arita V. T. Stannett 《Journal of polymer science. Part A, Polymer chemistry》1973,11(9):2127-2142
The kinetics of the radiation-induced polymerization of vinyl chloride in the presence of precipitants has been successfully described by a one-parameter equation as follows, where ?0 is initial monomer volume fraction, X is conversion, t is time, and k is reaction constant. The equation was confirmed for extensive conditions of temperatures and monomer concentrations in the case of polymerization in methanol. The degree of polymerization was related with the reaction constant k, initial monomer volume fraction ?0, monomer chain transfer constant Cm, conversion X, and the initiation rate I as follows, The factors which determine the value of the reaction constant k were elucidated through measurements of the reaction constant k and the degree of polymerization DP n. 相似文献