Influence of the polymer structure of polycarboxylate-based superplasticizers on the intercalation behaviour in montmorillonite clays

The influence of polymeric structure of polycarboxylate-ether (PCE) based superplasticizers on the intercalation behavior in sodium montmorillonite clay (Na-MNT) is investigated by performing in-situ X-ray diffraction (XRPD) on fresh, unaltered clay pastes. The use of this technique reveals the real influence of the PCE structure and of the PCE/clay dosage ratio on the expansion profile of the clay. This is not observed with the traditional XRPD methodology performed on dried clay pastes, which shows the same values of d-spacing despite using polymers of diverse structures. It is observed that PCE polymers with long side chains and high side chain density result in larger expansion. Additionally, polymers with a high anionic charge saturate the interlaminar space of montmorillonite at a lower dosage. The experimental results also indicate that clay exfoliation is critical in the intercalation process and the exfoliation tendency of the clay is influenced by the structure of PCE polymers. (C) 2019 Elsevier Ltd. All rights reserved.