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High-modulus poly(p-phenylenepyromellitimide) films
obtained using a novel gel-drawing technique
JIRO SADANOBU
∗
Polymer Research Institute, Teijin Limited, 2-1 Hinode-cho, Iwakuni Yamaguchi 740-8411, Japan
Abstract—A new concept for the processing and fabrication of rigid-rod polyimide, poly(p-
phenylenepyromellitimide), (PPPI) is proposed. In this approach, the highly swollen polyisoimide
gel-film was used as a precursor and was biaxially stretched using gel-drawing technique. The gel-
drawn polyisoimide film was converted to a polyimide film by heat treatment at above 350°C. The
gel-drawn PPPI film possesses a tensile strength of 500 MPa and a Young's modulus of 20 GPa.
Keywords
: Poly(p-phenylenepyromellitimide); polyimides; polyisoimides; gel-drawing; rigid-rod
polyimides.
1. INTRODUCTION
There has been an increasing demand for high-performance organic films with
dimensionally, thermally and mechanically improved properties from the view-
point of emerging electronics applications [1]. Current trend of downsizing the
electronics components, such as printed circuits, IC carrier tapes, chip scale pack-
agings, magnetic recording tapes and so on, additionally requires the thickness to
be smaller than 10
m but still maintaining good processability. For conventional
organic films such a low thickness range has not been reached because reducing
the thickness causes difficulties in material handling. To remedy the situation, de-
velopment of high-modulus organic thin films is highly promising. Although con-
ventional polyimide film has been widely used in the field of electronics, its
Young's modulus is limited to 10 GPa, which is not enough for thin film applica-
tions. In the last decade some Aramid films with enhanced Young's modulus have
been developed, however, the low hygroscopic stability limits their applications
in electronics [2]. Therefore, the development of high performance organic films
with high Young's modulus is still a challenge.
Poly(p-phenylenepyromellitimide), (PPPI) is the simplest form of crystalline
polyimides, depicted in Figure 1, prepared from pyromellitic anhydride and p-
µ
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