Poly(l-Lactic Acid)/Pine Wood Bio-Based Composites

Abstract

Bio-based composites made of poly(l-lactic acid) (PLLA) and pine wood were prepared by melt extrusion. The composites were compatibilized by impregnation of wood with γ-aminopropyltriethoxysilane (APE). Comparison with non-compatibilized formulation revealed that APE is an efficient compatibilizer for PLLA/wood composites. Pine wood particles dispersed within PLLA act as nucleating agents able to start the growth of PLLA crystals, resulting in a faster crystallization rate and increased crystal fraction. Moreover, the composites have a slightly lower thermal stability compared to PLLA, proportional to filler content, due to the lower thermal stability of wood. Molecular dynamics was investigated using the solid-state 1H NMR technique, which revealed restrictions in the mobility of polymer chains upon the addition of wood, as well as enhanced interfacial adhesion between the filler and matrix in the composites compatibilized with APE. The enhanced interfacial adhesion in silane-treated composites was also proved by scanning electron microscopy and resulted in slightly improved deformability and impact resistance of the composites.

Heterogeneous Bubble Nucleation by Homogeneous Crystal Nuclei in Poly(l‐Lactic Acid) Foaming

“…The diffraction pattern shown in Figure 9 is typical of 𝛼-crystal modification of PLLA: the spectrum presents main diffraction peaks at 2𝜃 = 16.5 and 19°, plus a reflection at 22.2°, which is observed only in PLLA containing 𝛼-crystals, and the reflection at 24.5°characteristic of 𝛼'-crystals is absent. [58,59] The X-ray profile of Figure 9 is in agreement with literature data, which indicate that foaming of semicrystalline PLLA leads to growth of 𝛼-crystals, even in the presence of nucleating sites, [60,61] proving the proposed strategy of foaming PLLA in the presence of HCN does not affect structural properties of PLLA foams.…”

Modification of the Release of Poorly Soluble Sulindac with the APTES-Modified SBA-15 Mesoporous Silica

“…A sharp, symmetrical minimum of 128 ms at about 182 K (−91 °C), depicted in Figure 6 , was attributed to the hindered rotation of methyl CH 3 groups around the threefold axes C3. For sulindac, the methyl group reorientation was characterized by the activation energy E a of 12.2 kJ/mol and a τ 0 value of 1.2 × 10 −12 s, which was confirmed by prior 1 H-NMR results [ 34 , 40 , 41 ]. In the low-temperature region, a decrease of the relaxation times T 1 was observed, and the contribution of another type of molecular motion was considered.…”

Thermal and Thermo-Mechanical Properties of Poly(L-lactic Acid) Biocomposites Containing β-Cyclodextrin/d-Limonene Inclusion Complex

“…TGA analyses were performed in the temperature range between 30 and 600 °C, at a heating rate of 10 °C min −1 , under a nitrogen atmosphere using a Netzsch TG 209 F1 apparatus (Selb, Germany) calibrated by analyzing several standards, including In, Sn, Bi, Zn, Al, and Ag. The decomposition onset temperature, T o , of approximately 10 mg samples, was determined at the intersection of tangents to two branches of the thermogravimetric curve [ 29 ]. Each measurement was preceded by an empty pan run, and subtracted from each thermogram to correct instrumental drift.…”