Elaboration of nanostructured polyurethane foams/OMMT using a twin-screw extruder in counter-rotating mode

Abstract

In this work, a new elaboration method for nanostructured foam polyurethane/organo-modified montmorillonite (PUR/OMMT) by in situ polymerization is proposed. A twin-screw extruder in the contra-rotation mode combined with reaction injection molding (RIM) as the polymerization process was used. The blended polyols, copolymer polyol (CPP) were included between the OMMT layers via the twin-screw extruder. Both the formulation of the PUR and the inter-foliar distance in the montmorillonite (MMT) were optimized. The effect of some parameters such as OMMT content and catalyst (triethylenediamine for PUR 3 and triethylenediamine+diamino-1,2 propane for PUR 4) was also investigated. The synthesized materials (OMMT, PUR and PUR/OMMT) were characterized by different methods, i.e., Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of evaluation tests, such as flammability and the tensile for the PUR 3+OMMT foams revealed that the optimum properties were obtained for PUR 3+2 % OMMT. The PUR 4 foam showed better mechanical and flame--retardant properties than the PUR 3 (r = -NCO/-OH = 1.15) foam. However, the PUR 4 + 2 % OMMT formula exhibited the most delayed flame diffusion and pronounced rigidity.Available on line at www.shd.org.rs/JSCS/ 1364 MAHMOUD, SAFIDINE and ZEGHIOUD motive, naval, furniture and building industries, and for shock absorption, padding and thermal or acoustic insulation. 1-5 PUR foams are present in all areas of daily life due to their various properties and applications. Despite all these advantages, these foams can constitute a peril in the event of fire. Currently, public opinion is very aware of this inflammability problem. Among the solutions to address this issue is the addition of organic flame-retardants in the polymer matrix. 6-8 However, most organic flame-retardants emit toxic gases.Nevertheless, both researchers and industrialists are interested in finding other solutions, such as the addition of graphite, 9-12 fibers, 13,14 montmorillonite, 15-26 nanocoating, 27,28 etc. The addition of montmorillonite in the polyurethane imparts noteworthy improvement to the relevant properties, especially if it is distributed on the nanometric scale. It enhances mechanical, thermal, barrier and flame retardant properties. 3 These improvements depend on the type of polymer, the ingredients used, the preparation process and the dispersion of the clay in the matrix. 3,29,30 Much work on the development of polyurethane foams modified with montmorillonite are reported in the literature. 15,[21][22][23][31][32][33] However, the use of a combination of grafted polyol (CPP) and polymeric diphenylmethane diisocyanate (PMDI) and/or diamino-1,2 propane as a catalyst has not been considered.The main goal of the present study consisted in the preparation of nanostructured foam polyurethane/OMMT with enhanced mechanical and flame-retardant properties. In order to incorporate the grafted polyols into the OMMT galleries, a twin-screw extruder oper...

Impact of microcrystalline cellulose extracted from walnut and apricots shells on the biodegradability of Poly (lactic acid)

“…The bands located at 1183, 1126 and 1080 cm −1 are attributed to C-O stretching vibrations (Gazzotti et al, 2019) while those situated at 1281 and 1747 cm −1 are attributed to bending and stretching vibrations of C=O bonds, respectively (Qu et al, 2010). The bands located at 2,995 and 2,933 cm −1 represent the asymmetric and symmetric stretching of C-H vibrations, and the bands located at 1383 and 1453 cm −1 are characteristic of symmetric and asymmetric bending of C-H vibrations, respectively (Mahmoud et al, 2018;Gazzotti et al, 2019). Low band intensity observed at 1200 cm −1 was attributed to the C-O-C bands and those at 868 and 953 cm −1 were attributed to C-C band stretching vibrations (Heidarian et al, 2017;Gazzotti et al, 2019).…”