Melt compounding of different grades of polystyrene with organoclay. Part 1: Compounding and characterization

Abstract

Nanocomposites of polystyrene (PS) with up to 20 wt% organoclay were prepared by melt compounding in a co‐rotating, intermeshing twin‐screw extruder. Three grades of PS with different molecular weights were used. In this paper we discuss preparation and characterization of the mixtures. Residence time and its distribution were measured by ultrasonics (US). They were found to be independent of the PS grade, but the US attenuation and sound velocity varied with the organoclay loading. According to the XRD diffraction data, the organoclay was dispersed into two types of platelet stacks evidenced by the diffraction peaks at about 2θ = 2.1 and 5.5°, i.e., with the interlayer spacings of d001 = 4.20 and 1.6 nm, respectively. Since neat organoclay has d001 = 1.93 nm, the first peak indicates intercalation by PS and the other a collapse of the interlamellar gallery during compounding. The XRD spectra depended on the organoclay content, but not on PS grade. According to TEM analysis, the degree of intercalation of organoclay in the polymer matrix is highest for the low‐molecular‐weight polystyrene. TEM results also confirm the collapse of interlamellar spacing in parts of the samples. FT‐IR spectroscopy showed that there was some thermal degradation of the onium compound present in the nanoclay. Polym. Eng. Sci. 44:1046–1060, 2004. © 2004 Society of Plastics Engineers.

Melt compounding of different grades polystyrene with organoclay. Part 3: Mechanical properties

“…Good results were also obtained using polycarbonate [18,19] or epoxy [20]. Generally, it is quite difficult to exfoliate clay in low-polarity polymers, such as polystyrene [21,22] or polyolefins [23].…”

“…These are coded as LMW, MMW, and HMW, for low (M w ϭ 230 kg/mol), medium (M w ϭ 270 kg/mol), and high (M w ϭ 310 kg/mol) weight average molecular weight respectively [21,22]. The organoclay (Cloisite 10A) is a MMT (cation exchange capacity [CEC] ϭ 0.926 meq/g, d 001 ϭ 1.17 nm) intercalated with 1.25 meq/g of di-methyl benzyl hydrogenated tallow ammonium chloride (2MBHTA), which increased the interlayer spacing to d 001 ϭ 1.92 nm.…”

“…As described in Part 1 of this series of articles [21], a Leistritz co-rotating twin-screw extruder TSE-34 (screw length/diameter ratio (L/D) ϭ 40) was used. The residence time and its distribution inside the TSE were measured using an ultrasonic probe.…”

“…XRD scans were obtained using an incident X-ray wavelength of ϭ 0.15406 nm at a scan rate of d /dt ϭ 1.5°/min. X-ray analysis was performed on the specimens prepared by compression molding at 200°C [21].…”

Melt compounding of different grades of polystyrene with organoclay. Part 2: Rheological properties

“…Characteristics of the material discussed in this paper were described elsewhere (43). Thus, XRD showed two peaks, located at 2 of about 2°and 5.5°.…”