Browsing by Author "Sarbandi, Mohammad Reza"

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Open Access
Study of the influence of nanoparticles on the performance and the properties of polyamide 6
(2011) Sarbandi, Mohammad Reza; Effenberger, Franz (Prof. Dr. Dr. h.c.)
The number of efforts in order to modify the properties of polymeric fibers by organic or inorganic particles has increased in recent times because of increasing interest of fiber research in hightech fiber applications. In addition to these attempts, the innovation of nanotechnology also leads to the development of nanoparticles for various end uses such as nanocomposite fibers. In this study spherical silica nanoparticles were introduced into polyamide 6 and drawn into filaments through a melt extrusion process. With two different particle diameters, different particle concentrations and types of surface modified silica as variables, preparation of polyamide 6/SiO2 nanocomposites were investigated for three different nanocomposite preparation methods (i) melt intercalation, (ii) solution intercalation and (iii) in-situ polymerization, while pure polyamide 6 was spun under the same condition as a reference. The study was carried out for multifilament nanocomposite fibers consisting of nano-silica fillers embedded in a fiber grade polyamide 6 matrix. Thus the effect of SiO2 nanoparticles on the thermal, structural, morphological and tensile properties of polyamide-silica nanocomposites fibers were investigated by using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and standard tensile testing methods, respectively. TGA results showed that thermal stability of nanocomposites was notably improved compared to pure polyamide 6. According to DSC and XRD results the introduction of different silica nanoparticles into the polymer matrix as well as the cooling rate in the preparation method caused a phase transformation of the crystals of the polymer matrix from α- to γ-form crystals. SEM observations show that In-situ polymerization and solution intercalation are suitable methods for the preparation of inorganic/organic nanocomposites which can avoid the agglomeration of inorganic particles in polymer matrices, moreover modified silica particle disperse more homogeneously in the PA 6 matrix in comparison with the unmodified silica particle. GPC and relative viscosity measurement indicate that by increasing the silica content the molecular weight of nanocomposites decreased in comparison to pure polyamide 6 which suggests that there is an interaction between silica and polyamide 6. This is supported by a change of the proportion of the amino and carboxylic acid end groups which not only prove a molecular weight reduction but also explains the observed decrease of tenacity of nanocomposite fibers. In contrast to these findings the modulus of PA 6/silica nanocomposite fibers show a tendency to increase with increasing silica content.