Birefringence studies of the stress-induced crystallization of rubbers

Abstract

The change in thc fraction crystallinity with time and elongation of synthetic cis-1.4polyisoprene is studied through simultaneous measurement of birefringence and stress. Results are compared with values estimatcd from the decrease in stress arising from the crystallization. Various mcthods for calculating the crystallinity from the data arc compared. This method proves to be a sensitive, convenient method for determination of crystallinity of such samples. ZlJSAMM ENFASSIJNG :Die Anderung der Kristallinitiit ids Funktion der Zeit und des Verstreckungsgrades von synthetischem c,is-l,4-Polyisopren wird durch gleichzeitige Messung der Doppelbrechung und der Zugspannung untcrsucht. Die Ergebnisse werden mit Werten vcrplichen. die aus der durch die Kristallisation bedingten Abnahme der Zugspannung abgeschltzt wurden. Verschiedene Methoden zur I3erechnung der Kristallinitiit aus den experimcntellcn Daten wcrdcn verglichcn. Es kann pcrcipt wcrden. dal3 diese Methodc cin cmpfindlichcs. einfach LU handhabendes Vcrkihrcn zur 13estimmunp der Kristallinitlit dieser Prohen darstellt.Professor Mark's studies of the theory of rubber elasticity were among his many noteworthy contributions to the development of polymer science. He was also one of the pioneers in the use of X-ray diffraction in

Molecular orientation and stress relaxation during strain-induced crystallization of vulcanized natural rubber

“…There is an advantage to this method compared with other methods using monochromatic light. [21][22][23][24] Because this method is relatively insensitive to the clarity of samples, estimation of birefringence is possible even when the specimen becomes turbid because of crystallization. Furthermore, the problem of multiple order (namely, the case of m41) in highly birefringent materials can be eliminated.…”

Biaxial Orientation Mechanism of Drawn Natural Rubber. I. Appearance of the Biaxial Orientation

“…Mitchell [13] studied uniaxially stretched NR sheet and calculated crystallinity and orientation based on WAXD. Stein and colleagues [14] evaluated molecular orientation of NR by birefringence. Recently, Tosaka et al [15] and Toki et al [16,17] reported the structural development of NR during uniaxial deformation through in situ WAXD measurements.…”

Optical studies of the stress‐induced crystallization of polymers

“…Hashiyama, Gaylord and Stein (6) subsequently applied the equation to the study of the crystallization of c-PIP, again assumingf, = 1 (substantiated by X-ray diffraction) and using the Guth (7)-Smallwood (8) expression…”

“…The intrinsic birefringence of the crystals was calculated from bond polarizabilities using the principal of tensor additivity (9) Where <is the average refractive index of the crystal and V is the volume per isoprene unit of the crystal; (b, -bJ0 is the anisotropy of the isoprene unit which is calculated using, for example, (6) where b, is the polarizability along thc principal axis of the isoprene unit and and (b2)z are the principal longitudinal and transverse polarizabilities of bond i . 0" is the angle between the axis of bond i and the longitudinal axis of the isoprene unit (which is alignrd along the c axis of the orthorhombic crystal).…”