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1966 Volume 8 Issue 1
1966, 8(1): 1-9
Abstract:
Copolymerization of acrylonitrile (AN) with acrylamide (AAm) in concentrated aqueous solutions of inorganic salts，such as 52％ NaSCN，60％ ZnCl2，34％ Mg (ClO4)2， and in various concentrations of aqueous solution of NaSCN at 60±0.1℃．initiated by azo-bis-isobutyronitrile，has been studied．It has been found that the monomer reactivity ratios of the monomer pair in various concentrations of inorganic salt solutions are almost similar to one another and also similar to the result obtained from the copolymerization carried out in water medium as reported by Reicherr．Copolymerization of Acrylonitrile with methyl acrylate (MA) in 52％ NaSCN and 64％ ZnCl2 has been also studied．Results show that the composition of AN-AAm，AN-MA Copolymers at any degree of oolymerization conversion is approximately in agreement with the results calculated from the Skeist equation．
Copolymerization of acrylonitrile (AN) with acrylamide (AAm) in concentrated aqueous solutions of inorganic salts，such as 52％ NaSCN，60％ ZnCl2，34％ Mg (ClO4)2， and in various concentrations of aqueous solution of NaSCN at 60±0.1℃．initiated by azo-bis-isobutyronitrile，has been studied．It has been found that the monomer reactivity ratios of the monomer pair in various concentrations of inorganic salt solutions are almost similar to one another and also similar to the result obtained from the copolymerization carried out in water medium as reported by Reicherr．Copolymerization of Acrylonitrile with methyl acrylate (MA) in 52％ NaSCN and 64％ ZnCl2 has been also studied．Results show that the composition of AN-AAm，AN-MA Copolymers at any degree of oolymerization conversion is approximately in agreement with the results calculated from the Skeist equation．
1966, 8(1): 21-27
Abstract:
Emulsion copolymerization of chloroprene and isoprene initiated by potassium persulphate has been investigated. When chloroprene and isoprene were copolymerized to approximately 80% conversion, only a small amount of gel occurred. The peak in the viscosity-conversion curve, followed by a marked drop, is usually a sign of gel formation, since the insoluble gel does not contribute to the viscosity of the solution. The product thus obtained has a markedly decreased rate of crystallization, and the brittle-point of the vulcanizates is 5℃lower than those of the corresponding vulcanizates from Neoprene type GN-A.
Emulsion copolymerization of chloroprene and isoprene initiated by potassium persulphate has been investigated. When chloroprene and isoprene were copolymerized to approximately 80% conversion, only a small amount of gel occurred. The peak in the viscosity-conversion curve, followed by a marked drop, is usually a sign of gel formation, since the insoluble gel does not contribute to the viscosity of the solution. The product thus obtained has a markedly decreased rate of crystallization, and the brittle-point of the vulcanizates is 5℃lower than those of the corresponding vulcanizates from Neoprene type GN-A.
1966, 8(1): 28-40
Abstract:
In relation to the graft copolymerization of cellulose using Ce4+as catalyst，the me-chanism of eellulose oxidation and the reaction sites on the cellulose macromolecular chain in Ce4+-H2O-cellulose system were studied．From the experimental data concerning the rate of reduction of Ce4+ to Ce3+ in aqueous solution，the photosensitive character of this system has been confirmed．From the rates of oxidation of eellulose and its related model compounds，such as hydrocellulose，cellobiose，dialdehydeceIlulose，glucose and methylglucoside，as determined in eerie salt solution，the kinetics of cellulose oxidation may be represented bv the fol- lowing equation：where [I]0，[II]0 and [III]0 are the initial concentrations of the functional groups of type I，II and III，and kI，kII and kIII are their reaction rate constants respectively．By determining and comparing the rate constants of the same type but of different cellulose model compounds，it was found that the values of k for the same functional group are approximately equal irrespective of the model compounds to which the particular type of functional group is attached．It was also confirmed that there are at least three oxidation sites on a cellulose macfomolecular chain．The sites of greater and medium reactivity are the aldehyde group and 5,6-glycol unit of the terminal anhydroglucose unit respectively．The least reactive site is the hydroxyl groups attached to the third position of the rest of anhydroglucose rings．Though the value of kIII is very small，nevertheless，the reaction of third position should not be neglected for the number of such hydroxyl groups is great． When cellulose is oxidized by ceric salt，it was found that one mole of terminal aldehyde group or 5，6-glycol unit consumes two moles of eerie salt and was finally con-verted into new aldehyde group．Cellulose free radical formed as an intermediate pro-duct initiates the graft copolymerization．Hence，it may be assumed that the copolymer of cellulose obtained by Ce4+ initiation is possibly a graft-block complex copolymer.
In relation to the graft copolymerization of cellulose using Ce4+as catalyst，the me-chanism of eellulose oxidation and the reaction sites on the cellulose macromolecular chain in Ce4+-H2O-cellulose system were studied．From the experimental data concerning the rate of reduction of Ce4+ to Ce3+ in aqueous solution，the photosensitive character of this system has been confirmed．From the rates of oxidation of eellulose and its related model compounds，such as hydrocellulose，cellobiose，dialdehydeceIlulose，glucose and methylglucoside，as determined in eerie salt solution，the kinetics of cellulose oxidation may be represented bv the fol- lowing equation：where [I]0，[II]0 and [III]0 are the initial concentrations of the functional groups of type I，II and III，and kI，kII and kIII are their reaction rate constants respectively．By determining and comparing the rate constants of the same type but of different cellulose model compounds，it was found that the values of k for the same functional group are approximately equal irrespective of the model compounds to which the particular type of functional group is attached．It was also confirmed that there are at least three oxidation sites on a cellulose macfomolecular chain．The sites of greater and medium reactivity are the aldehyde group and 5,6-glycol unit of the terminal anhydroglucose unit respectively．The least reactive site is the hydroxyl groups attached to the third position of the rest of anhydroglucose rings．Though the value of kIII is very small，nevertheless，the reaction of third position should not be neglected for the number of such hydroxyl groups is great． When cellulose is oxidized by ceric salt，it was found that one mole of terminal aldehyde group or 5，6-glycol unit consumes two moles of eerie salt and was finally con-verted into new aldehyde group．Cellulose free radical formed as an intermediate pro-duct initiates the graft copolymerization．Hence，it may be assumed that the copolymer of cellulose obtained by Ce4+ initiation is possibly a graft-block complex copolymer.
