Radiation-Induced Copolymerization of Trioxane with Styrene Oxide

Copolymerization of trioxane (TOX) and styrene oxide (STO) induced by gamma radiation was studied under varying operating conditions to see the effects of radiation dose, STO concentration, postpolymerization temperature, and duration on the polymer yield. Charging 5% STO with TOX STO conversion was 65% but yield was only 23% compared with 62% for the homopolymer. Molecular weight, melting point, density, and thermal stability of the copolymer samples were determined.     

Radiation-Induced Copolymerization of Trioxane with 1,3-Dioxolane

Copolymerization of 1,3-dioxolane (DOX) with trioxane in the solid state was studied by radiation. The effects of radiation dose, DOX concentration, postpolymerization temperature and duration on the copolymer yield, and DOX incorporation were investigated and compared with published data.     

Radiation-Induced Copolymerization of Thiophene with Maleic Anhydride

Radiation-induced copolymerization of thiophene with maleic anhydride has been studied. On the copolymerization in chloroform solution, the effects of dose rate, polymerization temperature, and, monomer composition and concentration on the yield and molecular weight of the copolymer were determined. The copolymerization proceeds via a radical mechanism with bimolecular termination of propagating polymer radicals, and the apparent activation energy is 5.3 kcal/mole. By NMR spectroscopy of copolymer, it was also found that these monomers copolymerize alternately to give a copolymer having structure I. In this copolymerization, the higher initial rates were obtained at an equimolar composition of monomers and by using solvents containing chlorine, such as CC1₄, CHC1₃, and C₆H₅C1.     

Radiation-Induced Copolymerization of Fluorine-Containing Monomers

Radiation-induced copolymerizations of various monomers, including perfluoro-olefines with CF₂ O and of α-olefines with monochlorotrifluoro-ethylene, have been studied. It was found that CF₂O can be copolymerized randomly via radical process, with most of monomers examined and that alternating copolymers can be obtained from the copolymerization of a-olefines with monochlorotrifluoroethylene. The structural study of these copolymers was carried out by infrared, X-ray diffraction and NMR measurements. The structure of isobutylene-monochlorotrifluoroethylene copolymer was determined precisely through proton and fluorine resonances.     

Radiation-Induced Cryogenic Copolymerization of Some Monomers with Sulfur Dioxide

A comparative study was performed on the radiation postpolymerization of a number of dienes and -olefins with sulfur dioxide occurring both on heating of the samples radiolyzed at 77 K and spontaneously by mutual dissolution. The cryopolymerization of sulfur dioxide with butadiene was studied in most detail. It was found that, unlike the case of the isoprene–SO₂system, a polycrystalline phase with the eutectic that corresponded to the equimolar composition was formed on rapidly freezing over the entire range of initial ratios between the butadiene and SO₂comonomers. It was suggested that the 1 : 1 donor–acceptor complex takes part in the postpolymerization process, and the monomers enter the resulting copolymer in a near-equimolar ratio. The copolymer obtained was found to behave as a crosslinked system. It is likely that a three-dimensional network resulted from the opening of C=C bonds in butadiene.     

烯烃高效催化剂及聚合与共聚合的研究

为中山大学高分子研究所烯烃配位聚合研究室在高效Ziegler-Natta催化剂、茂金属催化剂烯烃聚合与共聚合方面部分研究工作的概述。重点叙述了催化剂的设计、过渡金属配合物配体结构及聚合条件对乙烯、丙烯、1-丁烯、丁二烯、苯乙烯等烯烃单体聚合及共聚合活性以及聚合产物结构和分子量的影响。     

The Radiation-Induced Copolymerization of Methyl Methacrylate with Di- and Trimethacrylates

The rates and gel formation of the radiation-induced co-polymerization of a number of dimethacrylates and trimethylol propane trimethacrylate with methyl methacrylate has been studied in detail. The rates were found to be linked to the nature and amount of gel formed rather than to differences in the reactivities of the monomers.     

Radiation-Induced Copolymerization of Tetrafluoroethylene and Propylene. 2. Copolymerization in Solution

Copolymerization of tetrafluoroethylene and propylene in chlorofluorohydrocarbon solvents was carried out below room temperature with γ-rays from a ⁶⁰Co source. A remarkable rate-accerelating effect was observed in these solution systems, although the activation energies and the compositions of copolymers were almost the same as those in bulk system. The most effective solvent was found to be trichlorotrifluoroethane. Kinetic results of the copolymerization in trichlorotrifluoroethane solution system revealed the role of solvent to be complicated, with the possibility of affecting almost all reaction steps of the polymerization.     

Radiation-Induced Copolymerization of Acrylonitrile with Methyl Acrylate: Synthesis and Characterization

Radiation-induced copolymerization of acrylonitrile with methyl acrylate was carried out in aqueous medium at room temperature. Different compositions of the copolymer were prepared and characterized by IR, ¹H-NMR, thermal, and dielectric studies. NMR spectroscopy was used to determine the composition and stereochemistry of the copolymer. Glass transition temperature values (T_g ) were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss.     

The Radiation-Induced Polymerization and Copolymerization of Butadiene in Emulsion

Abstract

The polymerization of butadiene in emulsion initiated by ^{6 0}Co gamma radiation has been studied in some detail. Similar studies with styrene and styrene-butadiene comonomer mixtures were also conducted. The rates of polymerization were found to be much lower than anticipated from the reported k_p values for butadiene and for the comonomer mixtures. Styrene, on the other hand, polymerizes at normal rates. A number of possible explanations for this behavior is discussed.     

一氧化碳与烯烃共聚及其功能高分子

本文综述了一氧化碳与烯烃共聚合成聚酮的方法，共聚反应机理以及聚酮在合成其他功能高分子方面的应用。     

Radiation-Induced Copolymerization of Styrene and Cellulose at Low Dose Rates

A study has been made of the radiation-induced grafting of styrene to cellulose in the presence of cobalt 40 gamma irradiation at low total doses and dose rates. For copolymerization, What mans 41 filter paper was immersed in solutions of styrene in methanol at various monomer concentrations. The dose rates were varied from 140 to 3100 rads/hr while the total dose varied from lo³ to 2 × 10⁵ rads.

In the presence of oxygen the grafting results showed considerable scatter, but a statistical analysis revealed that at all concentrations a linear relationship existed between total dose and graft %. Three factors contributing to the variance about the regression line were examined. Residual oxygen in the solution, while not important at high dose rates, was shown markedly to contribute to the variance in the range examined. A linear dose-rate effect involving a decrease in graft with increasing dose rate was demonstrated. A LET effect also contributed to the over-all variance. Preliminary results indicate the presence of a maximum which may be a Trommsdorff effect.     

Emerging Palladium and Nickel Catalysts for Copolymerization of Olefins with Polar Monomers

Transition‐metal‐catalyzed copolymerization of olefins with polar monomers represents a challenge because of the large variety of substrate‐induced side reactions. However, this approach also holds the potential for the direct synthesis of polar functionalized polyolefins with unique properties. After decades of research, only a few catalyst systems have been found to be suitable for this reaction. Some major advances in catalyst development have been made in the past five years. This Minireview summarizes some of the recent progress in the extensively studied Brookhart and Drent catalyst systems, as well as emerging alternative palladium and nickel catalysts.     

Radiation-Induced Emulsion Copolymerization of Tetrafluorethylene with Propylene. The Behavior of the HF Formed

The radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene was carried out at room temperature in the presence of gaseous monomers. The formation of hydrofluoric acid in the course of polymerization was observed. The amount of HF formed increased linearly with the irradiation time at various dose rates in the early stage. The tendency was similar to that of time-polymer yield curves. The rate of HF formation was proportional to the first order of the dose rate. The amount of HF formed increased in the presence of oxygen and decreased remarkably above 1 wt% emulsifier, while the polymer yield decreased in the presence of oxygen and increased with the emulsifier concentration. A remarkable decrease in the amount of HF formed in higher emulsifier concentration is mainly attributable to chemical absorption or electrostatic capture of H⁺ ion on polymer particles produced. Hydrofluoric acid is mainly formed by reaction between primary products (e _aq ^? and H) from the radiolysis of water and organic fluoride (tetrafluoroethylene and emulsifier), and is little formed by reaction between primary products and copolymer produced. The G value of HF formation was in the order of emulsifier-water system > suspension polymerization > emulsion polymerization, while the polymer yield was in the order of emulsion polymerization > suspension polymerization.     

Direct and Tandem Routes for the Copolymerization of Ethylene with Polar Functionalized Internal Olefins

Transition metal catalyzed ethylene copolymerization with polar monomers is a highly challenging reaction. After decades of research, the scope of suitable comonomer substrates has expanded from special to fundamental polar monomers and, recently, to 1,1‐disubstituted ethylenes. Described in this contribution is a direct and tandem strategy to realize ethylene copolymerization with various 1,2‐disubstituted ethylenes. The direct route is sensitive to sterics of both the comonomers and the catalyst. In the tandem route, ruthenium‐catalyzed ethenolysis can convert 1,2‐disubstituted ethylenes into terminal olefins, which can be subsequently copolymerized with ethylene to afford polar functionalized polyolefins. The one‐pot, two‐step tandem route is highly versatile and efficient in dealing with challenging substrates. This work is a step forward in terms of expanding the substrate scope for transition metal catalyzed ethylene copolymerization with polar‐functionalized comonomers.     

Radiation-Induced Copolymerization of Vinyl Monomers onto Husk and Stem of Rice Cellulose

The husks and stems of grain comprise major products of agriculture processes and not very widely used in industry. The present study deals with refining such materials to suitable products. A detailed study on the graft copolymerization of styrene and acrylonitrile onto husks and stems of rice cellulose was carried out, a Co-60 source being used as a means of producing ionizing radiation. The effect of different factors, e.g., dose, water content, temperature, and monomer concentration, in the graft copolymerization was studied and optimum conditions are proposed for the reactions.     

Radiation-Induced Graft Copolymerization of Mixtures of Acrylic Acid and Acrylonitrile onto Cellulose

Graft copolymerization of mixtures of acrylic acid and acrylonitrile (AN) onto irradiated cellulose was studied. The effects of radiation dose, temperature, duration, and concentration of the monomers were investigated. The extent of grafting was found to increase with radiation dose, temperature, and duration. Grafting was higher with increasing AN concentrations.     

4-甲基-1-戊烯与烯烃共聚用催化剂的研究进展

4-甲基-1-戊烯(4M1P)是烯烃工业中一种重要的支链α-烯烃,它的主要用途是用于制备均聚物和共聚物。虽然绝大部分4M1P共聚物尚未进入工业化生产阶段,但由于共聚物作为一类新型的合成树脂具有突出的力学性能和光学性能,已成为国外聚烯烃领域的一个研究热点。本文阐述了4M1P与烯烃共聚反应催化剂包括Ziegler-Natta催化剂、茂金属催化剂及后过渡金属催化剂的开发研究现状;重点阐述了催化剂的结构对共聚物分子结构的影响;同时也简要介绍了二亚胺镍催化剂催化4M1P共聚反应作用机理,展望了这一领域的发展趋势。为开发高端聚烯烃新材料提供参考。     

Radiation-Induced Graft Copolymerization of Styrene to Polyvinyl Chloride) Latex in a Pilot Plant System

A pilot plant study of the radiation grafting of styrene to polyvinyl chloride) (PVC) latex is described. When correct extraction conditions are used less than 3% grafting took place. This is shown to be due to the low total radiation doses needed to polymerize the styrene in an emulsion system. A parallel study with PVC film did, however, lead to substantial true grafting. The G (radical) value for PVC film as determined by ESR was found to be 4.6.