Infrared Absorption Bands Possibly Associated with the Helical Structure of Polystyrene, Poly-<i>p</i>-methylstyrene and Poly-<i>m</i>-methylstyrene Prepared with Ziegler Catalyst

~sothermal crystallizat~on ~n bulk has be.en co~pared dilatometrically with linear polyethylene samples which ~ave been molded In different ways, IncludIng melt orientation and sintering of precipitated powders ~rom dIlute solutions. These experiments show significant differences in the crystallization kinetics, which In some cases cannot be removed even by prolonged heating of the melt prior to crystallization. The data have been ~nalyzed by an empiric~l expression in terms of nucleation and growth processes, according to the theoretIcal approach of Avraffil. The results suggest that, in general, the melted polyethylene is not in a true ther~?dynamic equ~lib~ium and includes some "quasi-indestructible" clusters, which act as heteroge-neou~ nuclei In the cr.rstall~atIon process. The nature and the amount of these nuclei depend on the molding, meltmg, and mechamcal history of the sample, so that the semicrystalline material may have a wide variety of structure.

show abstract

“…2 With higher To .and longer to the crystallization isotherm is slightly shifted towards increasing time scale.…”

Section: Influence Of the Melting Conditionsmentioning

confidence: 93%

Isothermal Crystallization Kinetics of Polyethylene. III. Influence of the Sample Preparation

Rabesiaka

Kovacs

1961

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

Poly‐p‐methylstyrene obtained with n‐amylsodium

et al. 1961

View full text Add to dashboard Cite

Polymerization of nuclear substituted styrene by ZIEGLER type catalysts has been studied by NATTA et a1.l) and they found many crystalline polymers, but polymerization of p-methylstyrene by alkylsodium has not been reported. We carried out polymerization of p-methylstyrene with n-amylsodium or Aljin catalyst in n-hexane a t low temperature. The polymers obtained-by these catalysts are suggested t o contain stereospecific polymer. c _Under nitrogen atmosphere 0.51 g. of metallic sodium was in 20 ml. of dry n-hexane, to which 1.07 g. of n-amyl chloride was added dropwise. The mixture was stirred a t 0°C. for 3 hours. Then 5 ml. of p-methylstyrene dissolved in 15 ml. of dry n-hexane were added dropwise to this catalyst. The polymerization mixture was stirred for 24 hours at 0 "C. and precipitated with methanol. Then the solid product was treated with aqueous hydrochloric acid followed by extraction with benzene or acetone.

show abstract

On the temperature dependence of dilute solution properties of polystyrene

Krigbaum

Mark

Pritchard³

et al. 1963

Makromol. Chem.

View full text Add to dashboard Cite

Solutions of polystyrene in decalin were examined by light-scattering over the temperature range 68-85"C., and by viscometry over the range 3O-11O0C., in order to investigate the anomalous transition reported by REISS and BENOiT. The present results indicate that the radius of gyration exhibits a small maximum in the vicinity of 75 "C., and the intrinsic viscosity deviates slightly from a smooth, theoretical curve in the range 50-90 "C. ; however, in neither case is the variation clearly beyond the experimental error. Thus, the data provide no clear evidence for any anomaly in the temperature dependence of the average molecular dimensions, which suggests that the transition may involve a change in the local arrangement of short sections of the molecular chain. Further methods for investigating the transition are proposed. ZUSAMMENFASSUNG:Um den von REISS und BENOIT berichteten anomalen Ubergang i m System Polystyrol-*) Duke University.

show abstract

Infrared Absorption Bands Possibly Associated with the Helical Structure of Polystyrene, Poly-p-methylstyrene and Poly-m-methylstyrene Prepared with Ziegler Catalyst

Cited by 44 publications

References 2 publications

Isothermal Crystallization Kinetics of Polyethylene. III. Influence of the Sample Preparation

Isothermal Crystallization Kinetics of Polyethylene. III. Influence of the Sample Preparation

Poly‐p‐methylstyrene obtained with n‐amylsodium

On the temperature dependence of dilute solution properties of polystyrene

Contact Info

Product

Resources

About