Heats of copolymerization of butadiene and styrene from measurements of heats of combustion

Abstract

The h eats of combustion of two sam ples of polybutadi ene and four cop olvm ers of butacli ene and styrene pr epared at 50° C (122° F ), and one sample of polybutadiene an d four copolym ers po lym eri ze d at 5° C (4 1 ° F ) were m eas ured in a bomb cal ori m eter. Th e stn ene contents in th e co polymers vari ed from approximate ly 8 to 55 weigh t percent.. A va lu e for t he heat of polymerization (or co polym eri zation) was calculated for each sample by comb ining th e exper im ent al valu e for t he h eat of combustion wi th other known t hermoch e.mical data. Th e m ean valu e obtai ned for th e h eat of polymerization (-tlI-J p 0) of polybutad lene IS 17.4 kcal per mono m er unit, and the values obtain ed for t he heat of copolym eri zation var ied fr om 17.1 to 17.7 kcal p er m onom er uni t . No app er ciab le differe nce was found betweep ti? e heats of copolym eri zation of t he 5° C and 50° C pol.vmers. Th e h eat of cop oly meri za t IOn can be repr ese n~ed a s a fun ction of styr ene conte nt of t he p olym er b.v a n equatIOn of a form den ved theor etICall y by Alfrey ancl Lewis, a lthough th e co ncli t ions und er whICh th e polym ers were form ed were su ch t hat som e of the as~u m pt i o n s und erl Yinp: t h e de ri vatio n of th e equation wer e not satisfi ed..

Determination of copolymer composition by combustion analysis for carbon and hydrogen

“…The carbon and hydrogen results are the mean values of five determinations; the sulfur results are the mean of three. Some of these results were utilized in the thermodynamic studies already published [ 12 , 13 ].…”

“…Table 7 shows values of the standard deviation of the carbon-hydrogen ratio R ′ found for a number of styrene-butadiene copolymers differing in styrene content. The elemental analyses for most of these polymers are given in papers on thermodynamic studies [ 12 , 14 , 15 ]. The values of standard deviation are essentially the same as those shown in table 6 for polybutadiene.…”

“…In the present instance one of the chief applications of the method was to measure the bound styrene content of samples to be used in determining the relationship of refractive index to the composition of SBR (GR–S) polymers [ 9 to 11 ]. Many of these samples were also used in studies of heats of combustion [ 12 ], specific heats, and other thermal properties [ 13 to 15 ] at NBS. The results of the analyses of these samples have already been reported in the published papers.…”

Elastomers

“…The mean value of the heat of polymerization of butadiene is given as 17.4 kcal. per mole, and the values obtained for the heat of copolymerization varied from 17.1 to 17.7 with no obvious trend (131).…”

Catalytic Polymerization Of Ethylene, 1,4-Butadiene, and Ethylene Oxide with No Solvent: Heat Effects, Kinetics, and Mechanisms

“…The I, II, and III values can be compared with the following data: À108.28, À93.60, and À119.9 (kJ/mol) (the last, for the reaction (C 2 H 4 O) (gas) ¼ (1/n) (C 2 H 4 O) n(liquid) ) obtained by using the heats of Catalytic Polymerization of Ethylene 77 combustion [6,7] and [8] , respectively, and the tabulated heats of monomer vaporization. The heat of EO vaporization at 298 K is equal to 24.94 kJ/mol [9].…”