Electrically Conductive Composite of Polyaniline and Poly(p-Phenylene-Terephthalamide)
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ELECTRICALLY CONDUCTIVE COMPOSITE OF POLYANILINE AND POLY(p-PHENYLENE-TEREPHTHALAMIDE) XIAN-TONG BI, C. WANG AND J.S. BAO Institute of Chemistry, Academia Sinica, Beijing 100080, China.
ABSTRACT The improvement of the processibility and mechanical properties of polyaniline (PAn) by processing a concentrated sulfuric acid solution of the mixture of chemically prepared conductive PAn powders and poly(p-phenyleneterephthalamide) (PPTA) in different weight ratios are presented. The concentrated sulfuric acid solution of PAn and PPTA were processed to films and threads, they are liquid crystalline conductive polymer c~mpo- 1 sites, the electrical conductivities of the composites are between 10 -10 s/cm. PAn enhanced the tensile strength of PPTA, but does not effect the elongation. The morphology of the PPTA/PAn composite surfaces are fiberlike texture. INTRODUCTION In recent years, the study of para-aromatic polyamide has become a very attractive subject. Due to the semi-rigid chain in polymers, poly(p-phenyleneterephthalamide) can form anisotropic liquid crystalline solution [1-5]. Fibers with high tensile strength and high modulus can be obtained by dry-jet wet-spinning of this kind of polymer solution. PPTA is a kind of lyotropic liquid crystalline polymer, if we can prepare a composite of conductive liquid crystalline polymer from polyaniline and poly(p-phenylene-terephthalamide), then a new material can be obtained. Polyaniline has been discussed in many papers during the past 120 years [6-9]. A series of polyanilines having the structure formulae [10] H H H HH (IS)
(lA)
[0]
if
H
[0]1
[R]
(2S)
(2A) or [1I1
Emeraldine base form H I ýO Naý
H_ (__ (
H NC
Cl Emeraldine hydrochloride
H N-)x
Cl
Mat. Res. Soc. Symp. Proc. Vol. 173. ©1990 Materials Research Society
[R]
348
The 2S form and the emeraldine hydrochloride form are electrical conductive polyaniline and all of the rest are insulators. The polyaniline powder can be processed to self-supported film, but the processibility and mechanical properties are very poor. In order to improve the processibility and mechanical properties of polyaniline, we have studied the electrochemical polymerization of aniline in the polyurethane matrix to form electrically conductive composites [12,13], which had the same electrical conductivity as polyaniline and the mechanical properties of pure polyurethane films. Our previous work showed that the composite retained the mechanical properties of the matrix material. In this paper, we report the chemical oxidative polymerized aniline to form liquid crystalline electrical conductive composites by means of mixing the concentrated sulfuric acid solution of polyaniline with the concentrated sulfuric acid solution of poly(p-phenylene-terephthalamide). EXPERIMENTAL
Synthesis of poly(p-phenylene-terephthalamide)
(PPTA)
Starting materials: p-phenylenediamine: commercial 1,4-phenylenediamine was purified by vaccum distillation, white solids, m.p. 140-141 'C. Terephthaloyl chloride: terephthaloyl chloride was prepared from t
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