سال انتشار: ۱۳۸۷

محل انتشار: دومین کنگره بین المللی علوم و فناوری نانو

تعداد صفحات: ۲

نویسنده(ها):

Ali Samadi, – Facility of Engineering, Tarbiat Modares University, Tehran, Iran;
Mehdi Razzaghi Kashani –

چکیده:

Organically modified layered silicates (organoclay) are increasingly used for reinforcement of polymeric materials. It has been reported that the dispersion of such minerals at the level of a few nanometers induces a significant improvement in mechanical properties, flame resistance and barrier properties, compared with the pure polymer [1,2]. In addition, these improvements may be obtained with low clay loading (typically less than 5%). There are several techniques used for dispersing organoclay at a nano-scopic scale, including the addition of organoclay during polymerization (in situ method), or to a solvent swollen polymer (solution blending), or to a polymer melt (melt intercalation method),or co-coagulating of rubber latex and clay aqueous suspension, as described in recent reviews [1–۳]. According to these techniques, two ideal structures defined as intercalated nanocomposite and exfoliated nanocomposite are commonly used to describe the state of dispersion [1,2]. In the former, the polymer chains are intercalated between the silicate layers, resulting in a well ordered alternating layered silicates and polymer chains. In contrast, in the exfoliated structure, the individual clay layers are dispersed in the polymer matrix. The term conventional composite or micro-composite is also used to describe the structure of nanocomposite containing the clay tactoids with the layers aggregated in unintercalated form. One of the most commonly used organically layered silicates is derived from montmorillonite (MMT). Its structure is made of several stacked layers, with a layer thickness around 0.96 nm and a lateral dimension of 100–۲۰۰ nm [4]. These layers organize themselves to form the stacks with a regular gap between them, called interlayer or gallery. The sum of the single layer thickness (0.96 nm) and the interlayer represents the repeat unit of the multilayer material, called d-spacing or basal spacing (d001), and is calculated from the (001) harmonics obtained from X-ray diffraction patterns. The clay is naturally a hydrophilic material, which makes it difficult to exfoliate in a polymer matrix. Therefore, the surface treatment of silicate layers is necessary to render its surface more hydrophobic, which facilitates exfoliation. Generally, this can be done by ion-exchange reactions with cationic surfactants, including primary, secondary, tertiary and quaternary alkylammonium cations [5,6]. This modification also leads to expand the basal spacing between the silicate layers due to the presence of alkyl chain intercalated in the interlayer. For polymer containing polar functional groups, an alkylammonium surfactant is adequate to promote the nanocomposite formation. In this work we studied the effect of modifier type, on physical mechanical property of butyl-clay nano-composite based on tire shaping bladders compound cured with phenolic resin curing agent. Nano-composites obtained with 4% clay content by melt blending. The structure of used montmorillonite modifiers in this work are shown In table 1. Curing properties was analyzed at 190 °C by rheometer. In order to study the structure of nano-composites, XRD experiments were performed in a scan range of 2 =1-10. For dynamic properties, DMTA test at the temperature -150 to 250 were used, and finally tensile stress–strain properties were measured according to ASTM D882 specifications