Nukushina, Yasuhiko

Sakurada, Ichiro

Kyoto University Research Information Repository

Title Statistical Mechanics of Anisotropic Swelling of CrystallinePolymersAuthor(s)Nukushina, Yasuhiko; Sakurada, IchiroCitationBulletin of the Institute for Chemical Research, KyotoUniversity (1953), 31(2): 141-142Issue Date1953-03-30URL http://hdl.handle.net/2433/75289RightType Departmental Bulletin PaperTextversionpublisherKyoto University15. Statistical Mechanics of Anisotropic Swelling of  Crystalline Polymers Yasuhiko NUKUSHINA and Ichiro SAxl1RAoA (Sakuracla Laboratory)    In the present study the entropy of anisotropic swelling was derived in a similar manner as the previous study for isotropic swelling, except that a modification factor on elastic entropy of swelling had been introduced.    Let us consider the following cycle:    • v/2 amorphous chains and (1) unswollenstructure v/2f crystalline parts interlinking of+ n solvent       + n solventchains and cry-(4) molecules    (2) moleculesscalline parts }' dissolved chains andswollen structure      crystalline parts (3)>                             interlinking of                             chains and cry-                             stalline parts   As the sum of the entropy of process (1), S1, and the entropy of process (4), AS,, is equal to the sum process (2), S2, and the entropy of process (3), S3, the entropy of swelling, A5;, is given by the following equation. AS, = S2 + S3 — S1(1) Introducing the calculated values of S2, S3 and S1 in the above equation, we obtain AS,•= -k(n In (1-v2)+v In v2+ v/4 (,l'12+ +/1 32—I1—A 2—A3 ) -v/2f1n (  V'/V-6 )(2)          T7T71-6 v2 = v/2y /(nV1+v/21),Z = Vz/V1• where V1, V2,  V, V' and a represent respectively molar volume of solute, molar volume of anamorphous chain, volume of system before swelling, volume of the system after swelling and the fraction of amorphous parts; Al and A'1 represent principal extension ratios of unswollen and swollen strncture.    The partial molal-free energy of dilution obtained by differentiating Eq. (2) and introducing heat of mixing of the van Laar form, is then AFl = RT[In(1-vz)+v2(1-2/Z)+vz%(a'12+a•_2+a'32)—1-(a12-Ia22+a32)y                               1             •(al'•a3'•as');1+/ivs2-fZ(17/v2-2+1/a)J.(3) Al=a1Al,A2=a2Al, A3=a3n1,A1=bA1               1=a'12'1,A'2=2'3=  a3A1. At equilibrium between swollen structure and pure solvent, AF1 is zero and we obtain ( 141 )           z  =  Vi/V, =       • ua 3{(ai's+a2 +a:,"')—b(a12-F (a~'•a~~'•a3)—2i;o— C/Zb~_f(1/cz 2+1/A (4)                                 1)22r(  2to+--3-+                                           v22    16. Studies on the Temperature rise and its Influence on the Degree           of Polymerisation in the Emulsion Polymerisation                         of Vinyl acetate Seizo OKAMURA and Takuhiko MOTOYAMA (Sakuracla Laboratory)    By many investigations on the emulsion polymerisation, it has already been recognized that the locus of polymerisation is in the micelles of deter-gent molecules in the earlier stage of polymerisation and is in the monomer-polymer particles in the later one. Recently through the studies by S. Okamu-ra (" Synthesis and Applications of Polyvinyl Emulsion" (in Japanese) 1949.) and by M. Matsumoto ("J. Chem. High Polymer (Japan) 7, 390, 1950) it has also been found the different ielationships between the degree and the con-version of polymerisation in both stages.    In the paper reported here are considered the relations between the degree of polymerisation and the rise of temperature in the emulsion poly-merisation of vinyl acetate. By the usage of sodium lauryl sulphate as emulsifier, the size of emulsion particles and also the amount of heat accu-mulated in the polymerising particles are both found to diminish markedly. From these effects, the branching polymerisation occurs to the less extent than in the case without any emulsifiers, and so the difference of the degree of polymerisation as polyvinyl-acetate (PAc) and as as alcohol (PA) is very small. The effects of agitation on the relationships mentioned above are shown in Figure-1. At the strong agitation the polymerisation occurs mainly in the swollen polymer particles and so PA, are found to increase but PA to decrease during the polymerisation proceeds.    Assuming that the heat of polymerisation is spent to warm the emulsion liquid and the emulsion particles and also to escape at constant rate throu-gh the wall of reaction vessel, the elevation of temperature in the emulsion particles is evaluated as shown in Figure 2. At the maximum temperature shown in figure (e. g. ca. 77'C.), the amount of monomer remaining in par-ticles reaches 50% or more. The boiling point of monomer in swollen state is considered to be higer than normal value (73'C)) and these relations are calculated by the Huggins-Boyer's equation ( 142 )

Statistical Mechanics of Anisotropic Swelling of Crystalline Polymers

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Statistical Mechanics of Anisotropic Swelling of Crystalline Polymers

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