Radical Copolymerization Of Ethylene Research Articles

Radical copolymerization of ethylene and 2‐phenyl‐3‐vinyloxirane

AbstractThe radical copolymerization of ethylene and 2‐phenyl‐3‐vinyloxirane was carried out under high pressure to obtain the corresponding copolymers. The structure of the obtained copolymers was discussed by the data of infrared and nuclear magnetic resonance.

The solvent effect on radical copolymerization of ethylene with vinyl acetate

The copolymerization of ethylene with vinyl acetate under 25 MPa pressure at 383°K has been studied in different solvents. The constants for chain transfer to the solvent were determined for the entire range being studied. It was shown that the solvent concentration in the reaction mixture has a substantial effect on the copolymerization rate and copolymer yield. The overall copolymerization rate was determined in different solvents. The effect of the solvent on the mechanism of chain termination was studied. The order of reaction was determined in respect of initiator concentration for three solvents. It was shown that the reaction system under the conditions of study, in presence of copolymer, is a heterophase one.

Synthesis of alternating and random copolymers of ethylene with maleic anhydride

The radical copolymerization of ethylene with maleic anhydride has been investigated over a wide range of pressure (10–150 MPa), temperature (70–235°) and comonomer concentrations (0·1–60 mole %) in the presence of various solvents and initiators. Only alternating copolymers are formed at 150°, irrespective of the initial ratio of monomers and pressure, and irrespective of the medium. Above 200° random copolymers containing 0·4–13 mole% anhydride units are formed. The relative reactivity of ethylene in the random copolymerization was equal to 0·045±0·019. The dependence of the rate of formation of alternating copolymers on the maleic anhydride concentration was expressed by an extremal type of relationship, a maximum being obtained at an equimolar ratio of monomers. It was found that the rate and degree of copolymerization depend on pressure and temperature, on the polarity of the solvent, and on the initiator concentration.

Radical copolymerization of ethylene with vinyl phosphonates under pressure

The reactivities (composition curves) found during the copolymerization of ethylene, as well as the copolymer densitities as a function of composition, have been used to divide the CH 2=CHPO(OR) 2 (M 2) monomers into 2 groups: 1) R=C 6 H 5 and C 2H 4Cl and 2) R=C 4 H 9 and iso-C 4H 9. This correlates well with the polarity differences of M 2. The first group is characterized by higher reactivities, especially when the M 2 content in the reaction mixture is high. The rapid drop of the reaction rate and of the mol. wt. of the copolymers, when the M 2 content is increased in the reaction mixture, and the relatively large rate of the M 2 homopolymerization, can be explained by the competition of the two mechanisms of chain transfer. An intramolecular reaction is dominant at the start and yields an intermediate P ∗ radical. Chain transfer is faster at a larger M 2 content and hydrogen will dissociate from R.

Radical copolymerization of ethylene with unsaturated organosilicon monomers under pressure

The rate of copolymerization of ethylene with the organosilicon monomers CH 2 = =CHSiR 3 (m), where R represents the alkoxy or the OSi(CH 3) 3 group, is about the same as the rate of homopolymerization of ethylene over a wide range of composition of the monomer mixture. With a low concentration of m in the reaction mixture, the conversion of m is approximately the same as that of ethylene when R is an alkyl, alkoxyl or (OSi (CH 3) 3 group; the conversion is considerably greater than that of ethylene when R is a phenyl or phenoxy group or Cl. As the concentration of m increases, the density of the copolymers increases when R is a phenyl or alkoxy group, and decreases when R is an alkyl or a OSi (CH 3) 3 group. The capacity of the copolymers to crosslink with vinylalkoxysilanes decreases as the length of the alkyl group is increased. Thermooxidative degredation of the high molecular crosslinked copolymers occurs at a slower rate, as compared with polyethylene.

Radical copolymerization with vinyl trimethyl- or vinyl triethylsilane under pressure

The radical copolymerization of ethylene with vinyl trimethyl- and vinyl triethylsilanes proceeds via vinyl silane double bonds with chain termination of a bimolecular character. As the silane content of the reaction mixture rises, the reaction rate and the molecular mass of products are rapidly reduced, and the MMD and composition of the copolymers take on a unimodal character. The composition curves do not fit the Mayo-Lewis equation, but this absence of agreement is unrelated to the phase state of the system. Over the entire range of composition r sil→0. On introducing vinyl silane units to the polyethylene the frequency and temperature intervals for α and β relaxation transitions are reduced as the amount of vinyl silane units rises. A study was made of features of the temperature dependence of the heat capacity for the copolymers. It was found that at moderate temperatures crosslinking processes do not occur in the copolymers. The coefficients were found for approximate calculation of the molecular mass of the polymers using the viscosimetric method.

The radical copolymerization of ethylene with dimethyl or diethyl maleate

The radical copolymerization of ethylene with dimethyl- or diethyl maleate was studied at 130°C at pressures of 500 and 1500 kg/cm 2 in the presence of tert.butyl peroxide as initiator. The relative reactivities of the monomers have been calculated. The ester concentrations have been found to affect the reaction rate.

Free radical copolymerization of ethylene

Free radical copolymerization of ethylene