Low‐density polyethylene/spherical silica (LDPE/SGS) nanocomposites, containing 1, 2, and 6 wt % neat and modified (having amine functional groups) silica nanoparticles, were prepared by melt mixing using a twin‐screw corotating extruder. To improve the dispersion degree of the nanoparticles, glicydyl methacrylate grafted ethylene/n‐octene copolymer (EOR‐g‐GMA) containing 0.6 wt % GMA was used as a compatibilizer. It was observed that mechanical properties such as tensile strength, Young's modulus, and impact strength increase and are mainly affected by the loading and size of silica nanoparticles as well as by the EOR‐g‐GMA. The addition of modified silica and EOR‐g‐GMA resulted in a further enhancement of mechanical properties due to the improved interfacial adhesion. Storage and loss modulus values of prepared nanocomposites measured by dynamic‐mechanical thermal analysis were sensitive to the microstructure of the nanocomposites. Higher storage and loss modulus are evidence that the nanocomposites became stiffer. By adding the modified silica and EOR‐g‐GMA further increase in storage and loss modulus were observed due to the better dispersion of silica nanoparticles and increased compatibility between silica and the LDPE matrix. Both permitted a much more efficient transfer of stress from the polymer matrix to the silica nanoparticles. The improved barrier properties of all nanocomposites can also be mentioned as a positive effect. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Nanokompozyty poliamid/nanokrzemionka o budowie sferycznej Streszczenie-Otrzymano nanokompozyty poliamidu 6 z nanocz¹stkami krzemionki (SGS) o budowie sferycznej, ró¿ni¹ce siê zawartooeci¹ (od 0,5 % do 4 % mas.) nape³niacza oraz wymiarami jego cz¹stek (60, 100 lub 130 nm). Okreoelono wp³yw obu tych parametrów na w³aoeciwooeci u¿ytkowe produktu na podstawie oceny masowego wskaŸnika szybkooeci p³yniêcia (MFR), statycznych i dynamicznych w³aoeciwooeci mechanicznych, odpornooeci cieplnej i chemicznej, palnooeci oraz ch³onnooeci wody. Wykazano, ¿e dziêki zastosowanej metodzie wytwarzania nanokompozytu, tj. wyt³aczania przy u¿yciu oecinaj¹co-mieszaj¹cej konfiguracji oelimaków wyt³aczarki jest mo¿liwe uzyskanie równomiernego rozproszenia cz¹stek SGS w nanokompozycie, co powoduje znaczne polepszenie badanych w³aoeciwooeci. Stwierdzono, ¿e cechy nanokompozytów ró¿ni¹ siê w zale¿nooeci od zawartooeci i wymiarów cz¹stek nape³niacza, przy czym SGS o wymiarach 60 nm wykazuj¹ tendencjê do tworzenia aglomeratów a nanokompozyty PA/SGS z udzia³em 4 % SGS o wymiarach 130 nm charakteryzuj¹ siê najlepszym zespo³em badanych w³aoeciwooeci. S³owa kluczowe: poliamid 6, nanokrzemionka, nanokompozyty, dyspersja, w³aoeciwooeci mechaniczne, w³aoeciwooeci u¿ytkowe. POLYAMIDE/SPHERICAL NANOSILICA NANOCOMPOSITES Summary-Nanocomposites of polyamide 6 and spherical silica nanoparticles (SGS) (Fig. 2), differing in filler content (0.5-4 wt. %) and filler particle size (60, 100 or 130 nm) (Fig. 1, Table 1) were prepared. The effects of both these parameters on the product functional properties [melt flow rate (MFR), static and dynamic mechanical properties, thermal stability, chemical resistance, flammability and water absorption (Table 2-10, Fig. 4, 5)] were determined. It was demonstrated that thanks to the method of nanocomposites' preparation, i.e. extrusion with shearing-mixing configuration of the screws, it was possible to obtain SGS particles uniformly dispersed in nanocomposite (Fig. 3) leading to significant improvement in the properties studied. It was found that nanocomposites features varied dependently on the filler content and size of its particles. SGS particles of 60 nm dimension showed the tendency to agglomerate. PA/SGS composites containing 4 wt. % of SGS of 130 nm size showed the best set of properties.

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