Characterization of twin‐screw‐extruder‐compounded polycarbonate nanoclay composites

Abstract

Polycarbonate nanocomposites were prepared by melt processing from two surface-modified montmorillonite organoclays. The intercalation spacing and degree of the dispersion were characterized with wide-angle X-ray diffraction and transmission electron microscopy, respectively. The polycarbonate nancomposites showed rather good dispersion of nanoclay, with a mixture of exfoliated, intercalated, and confined morphology. The effect of nanoclay on the mechanical response of specimens subjected to tensile and impact loading was investigated. Results demonstrated that nanocomposites based on nanoclay possess increased Young's modulus and yield strength. However, their ductility upon tensile loading is significantly affected. A transition from ductile to brittle deformation occurs at studied clay loadings. Notched impact strength experiments supported this, showing that impact strength decreases significantly as nanoclay content increases from 1 to 5 wt%, regardless how the nanoclay surface was modified. Thermal analysis demonstrated that addition of nanoclay leads to decreased thermal stability of polycarbonate suggesting, enhanced dynamics of polymer chains. Finally, the tribological properties of selected specimens were evaluated using a pin-on-disc, and the effect of nanoclay fillers on tribological properties is discussed. POLYM. ENG.

Fabrication and characterization properties of polypropylene/polycarbonate/clay nanocomposites prepared with twin-screw extruder

“…Tensile test results show that at high filler or PC loadings, ductility is reduced, which can be indicated by a significantly lower elongation at break for both. The observed mechanical results are similar to those reported in the literature [31,32,36].…”

“…The observed phenomenon can be attributed to improved interaction between the two phases in the presence of NC. On the other hand, it is well known that microsized agglomerates increase in size with increasing NC content and can change fracture mode from ductile to brittle deformation [31,32]. Therefore, it would be expected that the large amount of NC can act as stress concentration sites, leading to much less fracture resistance [33].…”

“…Not only nanodispersion including intercalation and exfoliation determines mechanical behavior of nanocomposites, but also microdispersion has a great influence. Microparticles can initiate failure caused by stress concentration at high NC content [31,36]. For the nanocomposite containing 3 and 5 wt% NC, the significant increase in Young's modulus was observed, whereas for further amounts of NC, improvement gradually decreases.…”

The processing of polycarbonate nanocomposites generated with various nanofillers

“…Some investigations prepared the materials by in situ polymerization (Rama and Swaminathan, 2010;Yoo et al, 2004) and others by polymer melt intercalation (Yoon et al, 2003a,b;Carrión et al, 2008;Nevalainen et al, 2009;Feng et al, 2012;Xiao et al, 2013;Suin et al, 2013Suin et al, , 2014Hsieh et al, 2004;Lee and Han, 2003). Some investigations prepared the materials by in situ polymerization (Rama and Swaminathan, 2010;Yoo et al, 2004) and others by polymer melt intercalation (Yoon et al, 2003a,b;Carrión et al, 2008;Nevalainen et al, 2009;Feng et al, 2012;Xiao et al, 2013;Suin et al, 2013Suin et al, , 2014Hsieh et al, 2004;Lee and Han, 2003).…”

Composites of Engineering Plastics with Layered Silicate Nanofillers: Preparation and Study of Microstructure and Thermomechanical Properties

“…Their results indicated that the stiffness of the nanocomposite was contributed by the clay loading instead of the concentration of the modifier. A series of PC/organoclay nanocomposites from two commercial surface-modified MMT were prepared by melt compounding using a twin screw extruder (Nevalainen et al, 2009). The PC nanocomposites showed rather good dispersion of nanoclay, with a mixture of exfoliated, intercalated and confined morphology.…”