Lamellae Evolution of Stereocomplex-Type Poly(Lactic Acid)/Organically-Modified Layered Zinc Phenylphosphonate Nanocomposites Induced by Isothermal Crystallization

Abstract

Stereocomplex-type poly(lactic acid) (SC-PLA)/oleylamine-modified layered zinc phenylphosphonate (SC-PLA/m-PPZn) nanocomposites are successfully fabricated using a solution mixing process. Wide-angle X-ray diffraction (WAXD) analysis reveals that the structural arrangement of the oleylamine-modified PPZn exhibits a large interlayer spacing of 30.3 Å. In addition, we investigate the temperature effect on the real-time structural arrangement of PPZn and m-PPZn. The results indicated that the lattice expansion of m-PPZn with increasing temperature leads to an increase in the interlayer spacing from 30.3 to 37.1 Å as the temperature increases from 30 to 150 °C. The interlayer spacing decreases slightly as the temperature further increases to 210 °C. This behavior might be attributed to interlayer oleylamine elimination, which results in hydrogen bonding destruction between the hydroxide sheets and water molecules. As the temperature reaches 240 °C, the in situ WAXD patterns show the coexistence of m-PPZn and PPZn. However, the layered structures of m-PPZn at 300 °C are almost the same as those of PPZn, after the complete degradation temperature of oleylamine. The morphology of the SC-PLA/m-PPZn nanocomposites characterized using WAXD and transmission electron microscopy (TEM) demonstrates that most partial delamination layered materials are randomly dispersed in the SC-PLA matrix. Small-angle X-ray scattering reveals that higher crystal layer thickness and lower surface free energy is achieved in 0.25 wt% SC-PLA/m-PPZn nanocomposites. These results indicate that the introduction of 0.25 wt% m-PPZn into SC-PLA reduces the surface free energy, thereby increasing the polymer chain mobility.

Thermo-Mechanical Performance of Polylactide Composites Reinforced with Alkali-Treated Bamboo Fibers

“…Compared to UTFC, the first peak of ATFC exhibits a slight shift to the higher angle of 17.1°. This could be explained by the fact that the lattice spacing of PLA crystal decreased by alkali treatment, leading to a more compact arrangement of its molecular chains [ 39 ]. Evidently, the height of the first peak of ATFC decreases in contrast to that of UTFC.…”

Melt Processing and Characterization of Biodegradable Poly(butylene succinate-<em>co</em>-adipate)/Hexadecylamine-Modified Layered Zinc Phenylphosphonate Nanocomposites

“…Melt processing of PBSA/m-PPZn nanocomposites. Hexadecylamine-intercalated PPZns were prepared by a similar approach reported previously [12,13]. The 1, 3 and 5 wt % PBSA/m-PPZn nanocomposites were fabricated by mixing the m-PPZn, PBSA, and polyoxyethylene bis(amine) at 105 °C using a single-screw extruder (Brabender Mix 30/50E) for 5 min.…”

“…However, the interlayer distance of PPZn is extremely small for the insertion of polymer chains into its interlayer gallery. To overcome this problem, organo-modifiers served as delamination compound to enlarge the interlayer spacing of PPZn have been applied [12,13]. The biocompatible and nontoxic organo-modifiers was selected owing to the preparation of fully green nanocomposites.…”

Development of Stereocomplex Polylactide Nanocomposites as an Advanced Class of Biomaterials—A Review

“…Despite MWCNT in PLLA/PDLA blends being able to yield stereocomplex crystallites, the poor dispersion of MWCNT in the polymer matrix leads to agglomerates and limits stereocomplex crystallization [ 95 ]. The presence of organic modifiers in nanoplatelets helps their delamination and improves their dispersion in the PLLA/PDLA matrix [ 86 , 101 , 102 ]. The presence of 1–10% PDLA in the PLLA matrix prevents the aggregation of carbon black (CB) and helps the formation of a CB nanoparticle network [ 110 , 117 ].…”