Influence of non-covalent modification of multiwalled carbon nanotubes on the crystallization behaviour of binary blends of polypropylene and polyamide 6.

Blends of polypropylene (PP) and polyamide 6 (PA6) with multiwalled carbon nanotubes (MWNTs) were prepared using different processing strategies in a twin-screw micro-compounder. The effect of MWNTs on the crystallization behaviour of the PP phase and the PA6 phase of the blend has been investigated through non-isothermal crystallization studies by differential scanning calorimetric analysis. Furthermore, the effect of the addition of the compatibilizer (PP-g-MA) and the modification of MWNTs (m-MWNTs) with a non-covalent organic modifier (Li-salt of 6 amino hexanoic acid, Li-AHA) has also been studied in context to the crystallization behaviour of the PP and PA6 phase in the blend. The crystallization studies have indicated a significant increase in bulk crystallization temperature of the PP phase in the blend in the presence of MWNTs. Moreover, the formation of 'trans-lamellar crystalline' structure consisting of PA6 'trans-crystalline lamellae' on MWNTs surface was facilitated in the case of blends prepared via 'protocol 2' as compared to the corresponding blends prepared via 'protocol 1'. Wide angle X-ray diffraction analysis has showed the existence of a ß-polymorph of the PP phase due to incorporation of the PA6 phase in the blend. Addition of MWNTs in the blends has facilitated further ß-crystalline structure formation of the PP phase. In the presence of m-MWNTs, a higher ß-fraction was observed in the PP phase as compared to the blend with pristine MWNTs. Addition of PP-g-MA has suppressed the ß-phase formation in the PP phase in the blend. X-ray bulk texture analysis revealed that incorporation of PA6 as well as pristine/modified MWNTs has influenced the extent of orientation of the PP chains towards specific crystalline planes in various blend compositions of PP and PA6.

Growth of textured nanocrystalline cobalt ferrite thin films by pulsed laser deposition.

Cobalt ferrite thin films have been deposited on fused quartz substrates by pulsed laser deposition at various substrate temperatures, T(s) (25 degrees C, 300 degrees C, 550 degrees C and 750 degrees C). Single phase, nanocrystalline, spinel cobalt ferrite formation is confirmed by X-ray diffraction (XRD) for T(s) > or = 300 degrees C. Conventional XRD studies reveal strong (111) texturing in the as deposited films with T(s) > or = 550 degrees C. Bulk texture measurements using X-ray orientation distribution function confirmed (111) preferred orientation in the films with T(s) > or = 550 degrees C. Grain size (13-16 nm for T(s) > or = 300 degrees C) estimation using grazing incidence X-ray line broadening analysis shows insignificant grain growth with increasing T(s), which is in good agreement with grain size data obtained from transmission electron microscopy.