Fractionation of isotactic polystyrene

Kawahara, Kazuo; Okada, Reisuke

doi:10.1002/pol.1962.1205616328

Cited by 12 publications

(7 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…30 This band exhibits little intensity variation during the crystallization process 31 as well as weak dichroism, 32 and thus is largely independent of crystallinity and orientation. Therefore, the 1155 cm 21 band was chosen as a reference band, 29,38 and all spectral data were normalized with respect to this band. The peak at 858 cm 21 is assigned to the CH out-of-plane bending vibration of the 1,2,4,6-tetrasubstituted benzene ring of PPO.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the ratio of the absorptions at 982 and 1155 cm 21 , H 982 /H 1155 , can be used as an indirect index of crystallinity of iPS. 29,38 Fig. 3B displays the values of H 982 /H 1155 at different positions in the nanorods and the bulk film, which were extracted from the data in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…iPS was kindly supplied by Idemitsu Kosan Co., Ltd., and PPO was purchased from Aldrich. To minimize the influence of polymers with different molecular weight forming gradient molecular composition 27,28,35 on the polymer crystallization behavior 36 in nanopores, the iPS and PPO were fractionated first by successive precipitation using toluene (for iPS) and CHCl 3 (for PPO) as solvents and methanol as the nonsolvent, 37,38 and then by a recycling preparative HPLC (Japan Analytical Industry Co., Ltd., LC-9104) equipped with an RI detector (JAI RI-7s) using CHCl 3 as eluent. iPS with M n of 121,000 (M w /M n = 1.16) and PPO with M n of 24,300 (M w /M n = 1.16) were obtained and used in this study.…”

Section: Experimental Sample Preparationmentioning

confidence: 99%

See 2 more Smart Citations

Characterization of an isotactic polystyrene/poly(2,6-dimethylphenylene oxide) nanorod blend with gradient composition and crystallinity

Takahara

2012

RSC Adv.

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Sample Preparationmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of an isotactic polystyrene/poly(2,6-dimethylphenylene oxide) nanorod blend with gradient composition and crystallinity

Takahara

2012

RSC Adv.

View full text Add to dashboard Cite

“…for 16 hrs. 3 (poises) Comparing the samples A and B it is striking that reprecipitation from toluene solution a t 70 "C with n-butanol improved the thermal stability by a factor 3.9 without lowering the ash content (see Table 1). in vacuum and compressed with a plunger by hand.…”

Section: Melt Viscometrymentioning

confidence: 97%

Study of molten isotactic polystyrene. II. The kinetics of thermal degradation from melt viscosity data

Boon¹,

Challa²

1965

Makromol. Chem.

View full text Add to dashboard Cite

Starting from the established relation: log r, = A + 3.4 log w,, the kinetics of thermal degradation of isotactic polystyrene has been investigated in terms of melt viscosities measured as a function of melting time at constant temperatures between 265 and 320 "C.Random chain scission predominates over radical chain depolymerization and can be described by a zero-order reaction with an activation energy E of about 39 kcal. /mole. At the same time, the kinetic plots permit evaluation of the temperature dependence of melt viscosity without interference by degradation. This leads to an activation energy for viscous flow E' of 20 =k 2 kcal./mole. As the same value hdds for atactic polystyrene; viscous flow seems not to be influenced by the stereoregularity of polystyrene. In addition to the above activation energies only a single run of melt viscometry with 1-2 g. of a new sample of isotactic polystyrene is needed for a quantitative prediction of its melt viscosity a t any practical melting time and temperature. ZUSAMMENFASSUNG:Ausgehend von der Beziehung: log r, = A + 3,4 log Ev, ist die Kinetik des thermischen Abbaus von isotaktischem Polystyrol durch Messung der Schmelzviskositaten bei konstanten Schmelztemperaturen zwischen 265 und 320 "C in AbhHngigkeit von den Schmelzzeiten untersucht worden. Der statistische Kettenbruch iiberwiegt die radikalische Kettendepolymerisation und kann durch eine Reaktion nullter Ordnung mit einer Aktivierungsenergie E von ca. 39 kcal/Mol beschrieben werden. uberdies gestatten die kinetischen Darstellungen eine Bewertung der Temperaturabhangigkeit der Schmelzviskositat ohne Storung durch Degradation. Dies liefert eine Aktivierungsenergie fur viskoses Fliefien E' von 20 f 2 kcal! Mol. Da derselbe Wert sich auch auf ataktisches Polystyrol bezieht, scheint es, daS das viskose FlieSen durch die Stereoregularitat des Polystyrols nicht beeinflufit wird. Aufier den obengenannten Aktivierungsenergien geniigt eine einzige Reihe von SchmelzviskositLtsbestimmungen an 1-2 g einer neuen Probe isotaktischen Polystyrols fur eine quantitative Voraussage uber ihre Schmelzviskositat bei jeder praktischen Schmelzzeit und Temperatur.

show abstract

“…Therefore it does not seem possible with this model to obtain a gaussian behavior of the chain as the experiment tends to show. Nevertheless, in order to examine more thoroughly the possibility of such a rigid helical structure of the chain, we have carried out, with this model and according to eq 5 of part I, a theoretical calculation of the weight average value of <r 2 )jx by means of the Kawahara and Okada's 20 ponderal distribution of molecular weights. The isotactic PS fractioned by these authors corresponds in fact fairly well to that used here, since it possesses a weight and number-average molecular weights equal to and q,= }50000, respectively, that is, a polydispersity the calculation of (r 2 )/x and weighted this result by the weight percentage of the corresponding fraction.…”

Section: Let Us Remark That the Reverse Transition (Tg')----+ (Gt) Ismentioning

confidence: 99%

Depolarized Rayleigh Scattering and Stereoregularity of Polystyrene Chains. II. Interpretation

Fourche

Lemaire

1973

Polym J

View full text Add to dashboard Cite

ABSTRACT:The molecular optical anisotropy of isotactic and atactic polystyrene, and their oligomers has been interpreted according to the rotational isomeric state model. The results obtained allowed us to determine the statistical weights of mesoand racemic 2,4-diphenylpentane and the respective orientation of the phenyl rings in these molecules. Analysis also showed that isotactic polystyrene in solution had the same local conformation as the meso pentane. This conformation consisted of a succession of very long helical segments of type 31• In the case of atactic polystyrene a conformation of identical nature was found, though the length of isotactic sequences was much smaller.Finally, this study shows that it has been possible to interpret, by means of conformational parameters of model compounds, all the experimental values observed for isotactic and atactic polymers, thus pointing out the utility of depolarized Rayleigh Scattering as a method for the determination of the average conformation of polymers as well as that of short chains.

show abstract

Fractionation of isotactic polystyrene

Cited by 12 publications

References 2 publications

Characterization of an isotactic polystyrene/poly(2,6-dimethylphenylene oxide) nanorod blend with gradient composition and crystallinity

Characterization of an isotactic polystyrene/poly(2,6-dimethylphenylene oxide) nanorod blend with gradient composition and crystallinity

Study of molten isotactic polystyrene. II. The kinetics of thermal degradation from melt viscosity data

Depolarized Rayleigh Scattering and Stereoregularity of Polystyrene Chains. II. Interpretation

Contact Info

Product

Resources

About