Rustam Hojiyev

In the present study, poly(ethylene terephthalate)-clay nanocomposite multifilament yarns were prepared using two commercial and four nanoclays synthesized from Reşadiye Na-montmorillonite (Na-MMT). Two type multifilament yarns, i.e., fully drawn yarn (FDY) and partially oriented yarn (POY), were melt spun. The FDY yarns were prepared using pilot type Buschaert SpinBoy II CC melt spinning machine with a masterbatch feeding ratio of 4–5% in order to meet industrial machine requirements. The POY spinning was made on the Barmag industrial machine, and the POY yarn was subsequently texturized. All multifilament yarns were prepared via the masterbatch approach, similarly used for the preparation of colored dope dyed yarns. The mechanical properties, flame retardancy, thermal stability, and morphology of produced yarns on melt spinning experiments were analyzed and discussed along with the effect of nanoclay properties such as thermal stability, polymer-clay compatibility, and particle size distribution.

Poly(ethylene terephthalate)/clay nanocomposite multifilament yarn was manufactured by conventional masterbatch approach. Poly(butylene terephthalate) was used as a carrier polymer in masterbatch steps. The masterbatches were diluted into pilot melt spinning machine and subsequently drawn with 2.65 ratios to prepare fully oriented yarn. The degree of dispersion in nanocomposite fibers was analyzed by X-ray diffractometry and scanning electron microscopy. Even though the addition of nanoclay reduced mechanical properties of nanocomposite fibers, dimensional stability could be improved at certain clay contents. The flammability properties were sufficiently improved, and no significant changes were observed with increasing clay content. The main novelty of this paper is the development of a proper approach for the selection of optimum carrier polymer for nanoclay in masterbatch preparation, as well as proper nanoclay for desired polymers. The acid-base approach is used in evaluating the surface free energy of commercial nanoclay and calculation the total interaction energies between polymer and clay surfaces. Such an approach gives adequate information about polymer-clay compatibility and provides a useful tool in the selection of optimum carrier polymer, as well as proper nanoclay for the desired polymer during masterbatch preparations.

In this study, the production of ultrapure Na-bentonite by centrifuge based techniques for organo and nano composite bentonite industry was investigated. Various parameters including centrifuging time, solids content, and g force were studied to determine the set points (cut size) for theoretical CEC (cation exchange capacity) and recovery limits. The experimental results were modeled using Response Surface Method (RSM) with high responses (regression > 85% and correlation coefficients > 0.85). it is shown that the commercial centrifugation equipment operating with residence time of 10–15 seconds and g values lower than 300 g such as Multi Gravity separator (MGS), Hydrocyclones and Falcon/Knelson concentrators are not suitable for obtaining pure quality Na-bentonite, since the set point size (5-8 µm) is higher than 2 µm which is defined for bentonite of high smectite contents. The RSM models demonstrate that only the kind of separators such as decanter centrifuges with operational g forces higher than 600 may exhibit the closest set point to 2 µm and thus enable the achievement of an ultra pure quality bentonite product. These assumptions obtained from the developed model were confirmed by running tests on Falcon and Mozley hydrocyclone separators.