Enhancements of clay exfoliation in polymer nanocomposites using a chemical blowing agent

Abstract

A novel approach for the enhancement of clay exfoliation in melt‐processed polymer/clay nanocomposites is reported. As‐received organoclay is pre‐treated with a blowing agent resulting in nanocomposites with superior properties.

Structure and properties of clay/recycled plastic composites

“…The intercalated nanostructures exhibited between 2 and 7 clay layers per stack with an average of 3.2 clay layers per stack. Using a blowing agent treated organomodified montmorillonite resulted in more exfoliated clay/R-PS nanocomposites, which is in good agreement with our previous findings on neat PS (Istrate and Chen, 2014). Typically, intercalated/exfoliated nanostructures occur inside melt processed nanocomposites due to the shear forces that are present during melt blending and the interfacial interactions between the polymer matrix and clay minerals (Fornes and Paul, 2003;Paul and Robeson, 2008).…”

“…7 By dispersing Clay in R-PE ( Fig 1C, Curve C1) the (001) diffraction peak shifted to slightly higher 2θ values indicating that conventional composites have formed. This is similar to the findings reported for neat Clay/PP composites and attributed to the immiscibility between the polymer and the organomodified montmorillonite and/or the degradation of the surfactant during melt processing (Chen and Evans, 2008;Istrate and Chen, 2014). Replacing the Clay with ADC-Clay, the XRD spectra ( Fig 1C, Curve C2) showed no significant (001) diffraction peaks between the 2θ values of 2° and 4°, where the (001) peaks for Clay ( Fig 1A, Curve A1), ADC-Clay ( Fig 1A, Curve A2) and Clay/R-PE ( Fig 1C, Curve C1) were previously encountered.…”

“…By treating the organomodified montmorillonite with the organic blowing agent, the diffraction peak shifted towards a higher 2θ value. The intercalation of ADC inside the interlayer space and the positive shift which was attributed to the removal of some surfactant molecules from the clay mineral interlayer space have been discussed in our previous works Istrate and Chen, 2014).…”

“…The organic content of the organomodified montmorillonite was previously determined from loss on ignition test to be 40% . The as-received organomodified montmorillonite was treated with azodicarboxamide (ADC), a well-known blowing agent, following a procedure described in our previous publication (Istrate and Chen, 2014). The resulting clays were denoted as ADC-Clay.…”

“…This work examines the structure and thermal and mechanical properties of clay/recycled polymer composites manufactured with an as-received organomodified montmorillonite (Organoclay Nanomer® I.44P) and a blowing agenttreated organomodified montmorillonite. These treated clay minerals have been previously used to manufacture clay/polymer nanocomposites with a higher degree of exfoliation and superior properties (Istrate and Chen, 2014). It is hypothesised that by dispersing these clay minerals in recycled polymer matrices polymer composites/nanocomposites with better clay dispersion and superior properties will form.…”