Effect of Halloysite Nanotube on Mechanical Properties, Thermal Stability and Morphology of Polypropylene and Polypropylene/Short Kenaf Fibers Hybrid Biocomposites

Abstract

In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and thermal stability of polypropylene (PP) and PP/kenaf fiber biocomposites has been investigated. Different volume contents of HNTs ranging from 1 to 10 vol.% were melt mixed with PP and PP/kenaf fibers. The volume content of kenaf fibers was kept constant at 30%. The morphology of HNTs within the PP matrix has been studied via scanning electron microscopy (SEM). The morphological results revealed that HNT was uniformly dispersed in the PP matrix already at a low concentration of 1 and 2 vol.%. The mechanical properties of the manufactured nanocomposites and hybrid biocomposites such as Young’s modulus, tensile strength, elongation at break, flexural modulus, flexural strength, and notched Izod strength have been measured. The results show that Young’s modulus and strengths have been improved along with the addition of low content of HNTs. Moreover, the gain of notched Izod impact strength obtained by the addition of short kenaf fibers was maintained in hybrids with low concentrations of HNTs. Finally, the thermogravimetric analysis shows that at 10% and 50% weight loss, the thermal degradation rate of the PP and PP/kenaf biocomposites decreased by the addition of HNTs.

Halloysite Nanotubes and Silane-Treated Alumina Trihydrate Hybrid Flame Retardant System for High-Performance Cable Insulation

“…For this purpose, ATH-sil was used not only as a flame retardant agent but also as a compatibilizer that improves mechanical and processing performance in the considered systems (especially hybrids). It should also be noted that HNT (Dunino) is characterized by a high specific surface area; easy access to active hydroxyl groups on the developed surface of the nanoplates (in the tubes they are inside them and are difficult to access); a diversified zeta potential on the surface silanol (negative) and aluminol (positive), which significantly extends the possibilities of creating bonds with polar polymers or with surface modifiers in the case of non-polar polymers; and a large number of active centers resulting from substitutions for Al and Si in the crystal structure and weak bonds between lamellar and tubular single crystals, facilitating grain disaggregation in the matrix [ 17 , 42 ]. Figure 5 represents the stress–strain curves for the EVA/LDPE blend and its compositions reinforced with HNT and ATH-sil nanofillers.…”

“…An important aspect is the predominance of lamellar crystals compared to tubular ones, which makes it possible to form more bonds on both the silane and the aluminol sides. It also allows obtaining a larger blockage area for the flow of oxygen and heat, which is important for increasing the fire resistance of the materials and improving their thermal indicators [ 17 , 42 ].…”

“…Therefore, one can modify the sample surface (e.g., silane modification) or mix it with other nanofiller in order to obtain a hybrid system of fillers with a positive hybrid effect on improving thermal stability and flame retardancy. HNTs are such a nanofiller that could significantly enhance the compactness and thermal stability of the barrier layer and improve the flame retardancy efficiency of different polymer matrices [ 17 , 18 , 19 , 42 ]. The barrier layer covering the polymer matrix surface could effectively cut off the heat and material exchange between the polymer matrix and the combustion flame zone and prevent further degradation [ 48 ].…”

“…In this case, the fillers were well dispersed in the matrix in the presence of silane-treated ATH. Another naturally occurring mineral nanofiller is halloysite nanotubes (HNTs), with a chemical formula of Al 2 Si 2 O 5 (OH) 4 •2H 2 O, with a high amount of 1D nanotubular structures exhibiting a high length-to-diameter ratio and low hydroxyl group density at the surface [17]. HNTs have been used in applications where high mechanical properties, thermal stability, and flame retardancy are desired.…”

Comparison of mechanical properties and thermal stability of graphene‐based materials and halloysite nanotubes reinforced maleated polymer compatibilized polypropylene nanocomposites

“…The observed decrease in impact strength of PP/HNTs/MAPP nanocomposite at HNTs content above 1 phr could be related to agglomeration of the nanoparticles which created stress concentration points in the nanocomposite on impact, thereby decreasing impact energy absorption. [57] In comparing the impact strength performances of GNP, GO, and HNTs based PP nanocomposites as shown in Figure 5, increased impact strength of PP/GNP2/MAPP nanocomposite at 160.8 J/m was significantly different (p < 0.05) compared to PP/GO1/MAPP nanocomposite at 131.1 J/m, as well, significantly different (p < 0.05) compared to PP/HNTs1/MAPP nanocomposite at 141.9 J/m. It is also observed that impact strength of PP/HNTs1/MAPP nanocomposite at 141.9 J/m was higher and significantly different (p < 0.05) compared to PP/GO1/MAPP at 131.1 J/m.…”