Modification of montmorillonite with poly(oxypropylene) amine hydrochlorides : Basal spacing, amount intercalated, and thermal stability - Wang, Yaqing (Beihang University. School of Material Science and Engineering) ; Wang, Xiaoqun (Beihang University. School of Material Science and Engineering) ; Duan, Yifeng (Beihang University. School of Material Science and Engineering) ; Liu, Yuzhong (Beihang University. School of Material Science and Engineering) ; Du, Shanyi (Beihang University. School of Material Science and Engineering)