Preparation of a Clay Composite Containing Poly(o-toluidine) and Halloysite, and Examining of Its Performance as a Humidity Sensor

Abstract

This study outlines the production of an electrically conductive clay-based composite containing the halloysite as clay mineral and poly(o-toluidine) (POT) as a conductive filler. In the study, conductive POT/halloysite composite was obtained by in situ oxidative polymerization of o-toluidine using ammonium persulphate (APS) as an oxidant between the halloysite layers. By changing the polymerization conditions such as polymerization time, o-toluidine concentration, APS, and the concentration of HCl solution used as the reaction medium, the composite with the highest conductivity (7.5×10-5 S.cm-1) was obtained. Structural and morphological changes and thermal behaviors that occurred after the composite formation was revealed using various characterization techniques such as FTIR, XRD, TGA, and SEM. The usability of the prepared POT/halloysite composite as humidity sensing material was tested in comparison with the pure POT component of the composite at a relative humidity (% RH) varied between 41-94 (%). Accordingly, it was found that the composite exhibited a fairly regular resistance change to varying relative humidity compared to pure POT polymer.

Keywords

• conductive clay composite
• poly(o-toluidine)
• halloysite
• humidity sensing

Poli (o-toluidin) ve Halloysit İçeren Bir Kil Kompozitinin Hazırlanması ve Nem Sensörü Olarak Performansının İncelenmesi

Abstract

Bu çalışma, kil minerali olarak halloysit ve iletken bir dolgu maddesi olarak poli (o-toluidin) (POT) içeren elektriksel olarak iletken kil bazlı bir kompozitin üretimini özetlemektedir. Çalışmada, iletken POT / halloysit kompoziti, o-toluidinin, halloysit tabakaları arasında oksidant olarak amonyum persülfat (APS) kullanılarak in-situ oksidatif polimerizasyon yöntemi ile elde edildi. Polimerizasyon süresi, o-toluidin derişimi, APS ve reaksiyon ortamı olarak kullanılan HCl çözeltisi derişimi gibi polimerizasyon koşulları değiştirilerek en yüksek iletkenliğe sahip kompozit (7.5×10-5 Scm-1) elde edildi. Kompozit oluşumundan sonra meydana gelen yapısal ve morfolojik değişiklikler ve termal davranışlar FTIR, XRD, TGA ve SEM gibi çeşitli karakterizasyon teknikleri kullanılarak ortaya konuldu. Hazırlanan POT / halloysit kompozitin nem algılama malzemesi olarak kullanılabilirliği, 41-94 arasında değişen bir bağıl nemde (% RH) kompozitin saf POT bileşeni ile karşılaştırılarak test edilmiştir. Buna göre kompozitin, saf POT polimere kıyasla değişen bağıl neme karşı oldukça düzenli bir direnç değişikliği sergilediği bulundu.

Keywords

• iletken kil kompoziti
• poli(o-toluidin)
• halloysit
• nem sensörü

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