Polypropylene fibers containing dispersed clays having improved fire performance. I. Effect of nanoclays on processing parameters and fiber properties

Abstract

While the present interest in the use of functionalized nanoclays as additives for improving tensile properties and fire performance in polypropylene thermoplastics has led to a considerable literature, little attention has been given to this polymer in fiber form. In this article, we report the conditions necessary for and the characteristics of filaments and tapes comprising dispersions of functionalized clay in polypropylene-clay prepared by melt compounding polypropylene in a twin screw extruder. A small fraction (1-3% w/w) of modified grafted polypropylene has also been included to improve dispersion of the clay. X-ray diffraction of hot-pressed films, coupled with transmission electron microscopic investigation has been used to assess the degree of dispersion of the clay. Clay dispersion at the nanolevel was observed by TEM, but intercalation was not evident from X-ray study. Compounded samples were melt-extruded into filaments using a single screw extruder and drawn prior to wind up. The physical properties of the clay-containing polypropylene filaments showed that presence of dispersed clay increased filament modulus and was supportive of having achieved some degree of nanodispersion. Selected filament samples had sufficiently acceptable textile properties to enable their knitting into fabric samples. The burning behavior of fabric and film samples were observed by limiting oxygen index and cone calorimetry at 35 kW/m 2 external heat flux. While the clay presence did not confer flame retardancy, it did change the burning character and encouraged some char formation.

Polypropylene fibers containing dispersed clays having improved fire performance. Part II: characterization of fibers and fabrics from PP–nanoclay blends

“…In Part 1, we demonstrated that as, has been generally demonstrated in the literature for a number of polymers [19], the addition of a small quantity of clay to PP fibres and fabrics improves the fire performance properties by lowering PHRR values [2]. In Part 2, we extend the work and report the burning behaviour of knitted fabrics produced from polypropylene fibres comprising several dispersed nanoclays and compatibilising copolymers in the presence of ammonium polyphosphate (APP) as a model conventional flame retardant.…”

“…In our previous communication [2] the MFI for PP after one passage through the twin screw extruder extruder has been reported as 36.0g/600s. The increase in MFI is a measure of polymer degradation induced by one extra thermal cycle [2].…”

“…In our previous communication [2] the MFI for PP after one passage through the twin screw extruder extruder has been reported as 36.0g/600s. The increase in MFI is a measure of polymer degradation induced by one extra thermal cycle [2]. With respect to matrix 1 formulations in Table 1 It can be seen from the data in Table 1 and Figure can be concluded that PP-5%Pb-3%E is an intercalated nanocomposite.…”

“…Improving the flame retardancy of polypropylene [1] and particularly fibres and textiles using nanoparticulate additives, is faced with the primary challenge of optimising the dispersion of otherwise hydrophobic particles such as montmorillonite clays, even when functionalised with relatively hydrophilic species as demonstrated in the first paper in this series [2]. While nanocomposites have attracted considerable interest as having the potential for reinforcement and flame retardants (FR) activity since 1997 due to their reported improved mechanical and fire properties [3][4][5], most of the published work to date in the nanocomposite fibre area has been on improving tensile and stiffness (as modulus) properties, in particular for nylon 6 [6][7][8][9] with melt processing variables [10][11][12] and even electrospinning [13] being of interest.…”

Poly(lactic acid)/Organoclay Nanocomposite Fibers: Preparation, Characterization and Curcumin Natural Dyeing

“…Nanoparticles, such as montmorillonite clay (MMT), normally reinforce the mechanical and thermal properties of nanocomposite fiber [24][25][26][27][28][29][30]. The dyeing of PLA fiber using nanoclay holds promise for the industry.…”