Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

15A/2005C012

Sequential drawing behavior of isotactic polypropylene film by time-resolved
WAXS/SAXS measurements
Takashi SAKURAI1*, Yoshinobu, NOZUE1, Tatsuya KASAHARA1, Noboru YAMAGUCHI1
and Yoshiyuki AMEMIYA2
1
Petrochemicals Research Laboratory, Sumitomo Chemical Co., Ltd., 2-1 Kitasode Sodegaura City,Chiba 299-0295, Japan
2
Graduate School of Frontier Sciences, The Univ. of Tokyo, Kashiwanoha Kashiwa City,Chiba 277-8561, Japan
Introduction
The sequential drawing is the deformation process ofthe highly oriented crystalline and amorphous chains intransverse direction perpendicular to the first drawing
direction. This operation is often performed to produce
isotactic polypropylene (iPP) film used in packaging andother applications. However, the structural evolution
during the sequential drawing is not well understood.
Recently, we have developed newly designed biaxial
film drawing machine and have successfully applied it for
in-situ observation of deformation behavior of iPP in aseries of drawing from first draw to second draw direction.
Experimental
As a typical example, we used here a commerciallyavailable Zieglar-Natta iPP with Mw of 4.4 × 105 g/mol,Mw/Mn of 5.1, melt flow rate index of 2 g/10min, and amelting temperature of 160.9 °C.
The specimen (20mm×20mm×0.5mmt) was preparedby pressing at 230 °C followed by cooling to room
temperature. In Figure 1, we briefly present the set up ofnewly designed biaxial drawing machine. Sequentiallybiaxial drawing tests were carried out at temperature
close to melting point (160 °C) and draw rate of 1mm/sec.
The specimen was at first stretched in the X1 direction
and then in the X2 direction, respectively.
Wide- and small-angle X-ray scattering (WAXS andSAXS, respectively) measurements were conducted at theBL-15A beam line. For tracing the structural change
during drawing, time-resolved two-dimensional (2D)
WAXS and SAXS patterns were measured with 0.5 sectime slices by using a CCD X-ray detector [1].

Debye-Scherrer rings. These rings started to change intoarcs, and the reflections became more spot-like (50 sec),
indicating an improvement of the c-axis crystallites (αform) oriented along the first draw direction [2]. As
times passed from first to second drawing process, thespot-like of the 2D WAXS started to change into the arcs
(55 sec) at first. Then, the 2D WAXS pattern showedring pattern (60 sec) followed by the arc pattern (80 sec),
which indicated c-axis crystallites oriented towards thesecond draw direction in the second biaxial drawing
process.
The 2D SAXS pattern before stretching consisted ofrings. It transformed to the elliptical pattern and thenshowed spot pattern with the scattering maximum on thehorizontal line and the streak-like pattern along thevertical line (50 sec) [2]. It is noted here that the spot andstreak-like patterns behave in quite different manner insequential drawing process. The spot was distorted into
arc pattern (55 sec) in the early stage of biaxial drawing
process followed by the diffuse spot (60 sec) towards thesecond draw direction, revealing immediate orientation ofcrystalline lamellae towards the second draw direction.
On the other hand, the streak changed into circle (60 sec)
by way of lozenge (55 sec) in the biaxial drawing process.
In final stage of second biaxial drawing, weak streakalong the horizontal line is recognized slightly.
WAXSSAXS

X20 sec

50 sec55 sec60 sec80 sec

X1
Grip

X1

X2

Figure 1 Newly designed biaxial film drawing machine
Results and Discussion
Figure 2 shows the time dependence of 2D WAXS andSAXS patterns observed for the sequential drawing
process. The 2D WAXS pattern before drawing exhibited

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Users' Report

Figure 2 The time dependence of WAXS and SAXSpatterns observed for the sequential drawing process.
First drawing: 0–50 sec; Second drawing: 50-80sec.
References[1] Y. Amemiya et al., Rev. Sci. Instrum. 66, 2290 (1995).
[2] T. Sakurai et al., Polymer, 46, 8846 (2005).
* sakurait2@sc.sumitomo-chem.co.jp