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Mechanochemical initiation of polymerization of crystalline salts of acrylic acid
Abstracts *MECHANOCHEMICAL INITIATION OF POLYMERIZATION OF ACRYLIC ACID
l 67 OF CRYSTALLINE SALTS
V. A. K a r g i n , V. A. K a b a n o v a n d N. Y a . I ~ a p a p o r t - M o l o d t s o v a , V y s o k o m o l . s o e d i n . 3: ~ o . 5, 7 8 7 - 7 9 3 , 1961. IT has been shown that rapid polymerization of crystalline salts of acrylic and methacrylie acids takes place during their vibratory disintegration in the presence of small amounts of solvent. Polymerization also takes place in the absence of solvent b u t at considerably lower rates. The small amounts of solvent sharply increasing the polymerization rate practically set up "near melting" conditions. The dependence of the molecular weight of the polymer upon the a m o u n t of solvent in the reaction mixture during the disintegration process was found to possess a maximum, coinciding with a m a x i m u m on the curve depicting the dependence of the yield upon the same factor. A mechanism for the meehanichemical induction has been proposed according to which in the lattice of the ionic crystals defects of the type of cationic or anionic vacancies are created. Their interaction with the neighbouring molecules of monomer initiates the chain propagating reaction. Rapid polymerization of the monomer has been shown to be initiated in the absorption layer of silica gel particles when the silica gel is dispersed in a saturated aqueous solution of sodium acrylate. The part played b y the preliminary ordering of the monomer molecules in conjunction with a certain a m o u n t of their mobility in the realization of rapid polymerization has been stressed. TEMPERATURE DEPENDENCE OF THE DIPOLE-ELASTIC RELAXATION OF POLYMERS
G. P. M i k h a i l o v , A. M. L o b a n o v a n d V. A. S h e v e l e v , V y s o k o m o l . s o e d i n . 3: No. 5, 7 9 4 - 7 9 7 , 1961. TIlE temperature dependence of the dipole-elastic relaxation of polyvinylaeetate, p01ymethylacrylate, polyethylacrylate and polyethyleneterephthalate has been investigated b y the dielectric loss method. Measurements were carried out at high and ultra-high frequencies. The l o g r - 1 / T relation of the polymers in the high elastic state has been shown to be described b y a straight line with a break at 60-70 ° above the glass transition temperature. The apparent activation energy above the break temperature was found to b e 2-4 times less t h a n that observed in the region of audio-frequencies and to possess a value of 15-20 kcal/mole. The effect of plasticization on the nature of the logz-1/T relation has been investigated a n d it has been shown t h a t for PVA plasticized with 30~) dibutyl phthalate the relation is described by a curve with a smoothly changing slope. POLYMERIZATION OF CHLOROPRENE BY ORGANOMETAL COMPOUNDS
B. L. E r u s a l i m s k y , A. V. M e r k u r y e v a a n d N . P . B a i k o v a , V y s o k o m o l . s o e d i n . 3: No. 5, 798, 1961. DATA are given for the polymerization of chloroprene by organolithium a n d organomagneslum compounds. Butyllithium and the system butylmagnesium iodide -~ dibutylmagneslum were used as catalysts. For this system the polymerization rate at 60 ° in the initial period (catalyst cone. 0.012-0-025, monomer cone. 2.5 mole/1.) is about 5% per hour. For The Publisher will be pleased to quote for the supply of a full English translation of any papers abstracted in these pages.
l 67 OF CRYSTALLINE SALTS
V. A. K a r g i n , V. A. K a b a n o v a n d N. Y a . I ~ a p a p o r t - M o l o d t s o v a , V y s o k o m o l . s o e d i n . 3: ~ o . 5, 7 8 7 - 7 9 3 , 1961. IT has been shown that rapid polymerization of crystalline salts of acrylic and methacrylie acids takes place during their vibratory disintegration in the presence of small amounts of solvent. Polymerization also takes place in the absence of solvent b u t at considerably lower rates. The small amounts of solvent sharply increasing the polymerization rate practically set up "near melting" conditions. The dependence of the molecular weight of the polymer upon the a m o u n t of solvent in the reaction mixture during the disintegration process was found to possess a maximum, coinciding with a m a x i m u m on the curve depicting the dependence of the yield upon the same factor. A mechanism for the meehanichemical induction has been proposed according to which in the lattice of the ionic crystals defects of the type of cationic or anionic vacancies are created. Their interaction with the neighbouring molecules of monomer initiates the chain propagating reaction. Rapid polymerization of the monomer has been shown to be initiated in the absorption layer of silica gel particles when the silica gel is dispersed in a saturated aqueous solution of sodium acrylate. The part played b y the preliminary ordering of the monomer molecules in conjunction with a certain a m o u n t of their mobility in the realization of rapid polymerization has been stressed. TEMPERATURE DEPENDENCE OF THE DIPOLE-ELASTIC RELAXATION OF POLYMERS
G. P. M i k h a i l o v , A. M. L o b a n o v a n d V. A. S h e v e l e v , V y s o k o m o l . s o e d i n . 3: No. 5, 7 9 4 - 7 9 7 , 1961. TIlE temperature dependence of the dipole-elastic relaxation of polyvinylaeetate, p01ymethylacrylate, polyethylacrylate and polyethyleneterephthalate has been investigated b y the dielectric loss method. Measurements were carried out at high and ultra-high frequencies. The l o g r - 1 / T relation of the polymers in the high elastic state has been shown to be described b y a straight line with a break at 60-70 ° above the glass transition temperature. The apparent activation energy above the break temperature was found to b e 2-4 times less t h a n that observed in the region of audio-frequencies and to possess a value of 15-20 kcal/mole. The effect of plasticization on the nature of the logz-1/T relation has been investigated a n d it has been shown t h a t for PVA plasticized with 30~) dibutyl phthalate the relation is described by a curve with a smoothly changing slope. POLYMERIZATION OF CHLOROPRENE BY ORGANOMETAL COMPOUNDS
B. L. E r u s a l i m s k y , A. V. M e r k u r y e v a a n d N . P . B a i k o v a , V y s o k o m o l . s o e d i n . 3: No. 5, 798, 1961. DATA are given for the polymerization of chloroprene by organolithium a n d organomagneslum compounds. Butyllithium and the system butylmagnesium iodide -~ dibutylmagneslum were used as catalysts. For this system the polymerization rate at 60 ° in the initial period (catalyst cone. 0.012-0-025, monomer cone. 2.5 mole/1.) is about 5% per hour. For The Publisher will be pleased to quote for the supply of a full English translation of any papers abstracted in these pages.