Melt compounding of various polymers with organoclay by shear flow

We studied melt compounding of polymer/organoclay composites by shear flow in a rotating cylindrical mixer to investigate an effect of shear stress on the dispersion state of clay. The commercial organoclay, which is intercalated by dimethyl benzyl stearyl ammonium ion between clay platelets, and four kinds of commercial polymer (polystyrene (PS), poly(lactic acid) (PLA), polyamide(PA6), and poly(butylene succinate) (PBS)) were used in this study. According to the TEM photographs, there is exfoliated clay in PA6/organoclay composite, but the exfoliated clay cannot be seen in other polymer/organoclay composites. We calculated the value of clay dispersion from the low magnification TEM photograph, called the dispersion coefficient to consider the micro level dispersion of the clay in a polymer matrix. Generally, the dispersion coefficient increases with shear stress. However, the dispersion coefficients in case using PA6 and PBS as the matrix, whose melts have low viscosity, are larger than those in case using PS and PLA, whose melts have high viscosity. According to XRD results, d 001 peak originated from organoclay mostly shifted to the low value of angle for PA6/organoclay composite and began shifting to the low value of angle for PBS/organoclay composite. However, there is a peak for PS and PLA based organoclay composites. From the cases of PA6 and PBS in the DMA results, the storage modulus increases with an addition of organoclay. These results imply that low viscosity polymer is typical easy to get the composites with intercalated clay by melt compounding. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers