Melt-compounding methods

Much effort has gone into preparing rubber-clay nanocomposites based on NR as described in the earlier section. However, the dispersion of such nanoclays in non-polar NR matrices was very poor. In this section we would like to outline the preparation and characterization of NR-clay nanocomposites in the presence of certain eompatibilizers added into the system externally. For instance, Teh et al. prepared NR-OMt nanocomposites by a melt compounding method. ENR 25 and ENR 50 were used as compatibilizers. Pristine MMT was modified with oetadecyltrimethylamine and abbreviated as MMT-ODTMA. The amount of organoclay was only 2 phr while the amount of ENR was varied. NR-MMT-ODTMA showed mostly intercalated structure of the... 

Likozar et al. [148] obtained NBR/hydrogenated NBR mixed with MWCNTs using a melt compounding method, cured with peroxide, and further mixed with a two-roll mill. The resulted composites showed improved hardness, elastic modulus, tensile strength, elongation at break, and tear strength compared with noncured... 

The performance of CNT-based polymer composites include the extent to which the CNTs can be wetted by a given polymer and the resultant adhesion between the nanotube and the surrounding polymer matrix material. Therefore, the interface between the polymer matrix and the reinforcement plays a crucial role in the physical properties of the composites. Several techniques like physical processing and melt compounding methods (ultrasonication, milling, or grinding) are known [130] to be efficient at dispersing CNTs into polymer matrices (Table 9). 

Table 4.1 Thermal and mechanical properties of various PHA blends prepared using the melt compounding method.

A nylon 11-clay nanocomposite was prepared using the melt compounding method. X-ray diffraction and TEM observations showed that this technique formed an exfoliated nanocomposite at low concentrations of clay (less than 4wt.%) and that a nanocomposite with both exfoliated and intercalated clay layers was formed at high clay concentrations. TGA, DMA and tensile tests showed that the thermal stability and mechanical properties of the exfoliated nanocomposite were superior to those of the intercalated nanocomposite material (with higher clay content). The superior thermal stability and mechanical properties of the exfoliated nanocomposite were attributed to the organophilic clay being dispersed stably and densely in the nylon 11 matrix. 

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