The Role of Functional Group on the Exfoliation of Clay in Poly(L‐lactide)

Abstract

Summary: A new method was attempted to improve the interaction between poly(L‐lactide) (PLLA) with a commercially available organoclay, Cloisite 25A (C25A), which was functionalized with (glycidoxypropyl)trimethoxysilane to introduce epoxy groups, and is referred to as twice‐functionalized organoclay (TFC). Tethering PLLA molecules to the epoxy groups on the surface of the TFC was attempted by melt compounding. X‐Ray diffraction and transmission electron microscopy images showed that fully exfoliated PLLA/TFC nanocomposites were prepared successfully.Transmission electron micrographs of the PLLA composites of the three clays used here.imageTransmission electron micrographs of the PLLA composites of the three clays used here.

Effect of the silane modification of clay on the tensile properties of nylon 6/clay nanocomposites

“…34 The FTIR spectrum of C25AN in Figure 1 reveals that the peak at 3638 cm À1 of C25AN, corresponding to the stretching band of the terminal SiAOH on the silicate surface, was much less intense than that of pristine C25A; this confirmed the occurrence of a chemical reaction between the hydrolyzed silane monomers or oligomers with the silanol groups of C25A. Wei et al 35 and Chen and coworkers [31][32][33] observed similar results when they treated C25A with GPS. Figure 2 discloses the FTIR spectrum of C25AI.…”

“…Figure 3 presents XRD patterns of C25AE, C25AI, and C25AN, respectively. The modification with the silane compounds shifted the XRD peak of pristine C25A to a slightly lower angle, which indicated that the interlayer spacing of C25A was somewhat enlarged, that is, from d 001 ¼ [31][32][33] observed that d 001 of C25A was almost equivalent to that of C25AE. The different experimental results seem to originate from the fact that Chen and coworkers 31-33 modified C25A with GPS at room temperature, whereas the temperature used for the same purpose was 80 C in this study.…”

“…Evidence of the grafting of the silane compounds to C25A was provided by corresponding Fourier transform infrared (FTIR) spectra. [31][32][33] The morphology and mechanical properties of the resulting nylon 6/clay composites were investigated in accordance with the functional groups introduced onto the surface of the silicate layers.…”

“…1,[31][32][33] Silane coupling agents were chosen for the modification of Cloisite 25A (C25A), a sodium montmorillonite modified by an ammonium salt bearing long alkyl chains.…”

Synthesis and characterization of dual‐functionalized laponite clay for acrylic nanocomposites

“…[6][7][8][9][10][11][12][13][14] However, there are only a few reports of preparing dual-functional clays by combining the two modification methods. [15][16][17][18][19] A twice-functionalized organoclay (TFC) was described involving reaction of a silane agent (glycidoxypropyl trimethoxysilane) with C25A, a montmorillonite modified with a quaternary ammonium salt. [15][16][17][18] Polymer nanocomposite compounded with this TFC showed improved elongation at break as well as increased tensile modules and tensile strength.…”