Kinetic Analysis on Effect of Poly(4-vinyl phenol) on Complex-Forming Blends of Poly(L-lactide) and Poly(D-lactide)

Abstract

Differential scanning calorimetry (DSC), Fourier transformed infrared spectroscopy (FT-IR) and polarized optical microscopy (POM) characterizations were performed to reveal interaction between amorphous poly(p-vinyl phenol) (PVPh) and crystalline stereocomplex of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA). The negative value of the interaction parameter 12 clearly confirms a thermodynamic miscibility in the ternary blend. At low contents, PVPh is well dispersed in the ternary blends, but PVPh may aggregate to nanodomains by self-associated hydrogen-bonding upon annealing. In addition, PVPh serves as an effective agent in reducing the spherulite sizes of the PLLA/PDLA crystals, which may be favorable in controlling the macroscopic properties. The Avrami and Tobin kinetic analysis methods were carried out to analyze the nonisothermal crystallization data, and the results showed that the ternary blends with an optimal range of 2-10 wt % PVPh were faster in the crystallization rate and smaller in the spherulite size than those with no PVPh or with PVPh contents greater than 10 wt %. Ternary blend containing higher PVPh contents may form large phase-separated domains and growth of the stereocomplex is hindered under the nonisothermal crystallization condition.

Preparation and Properties of sc-PLA/PMMA Transparent Nanofiber Air Filter

“…No melting peak of PLLA/PDLA homo-crystallization at around of 170 °C was observed for all the blend nanofibers. T m of sc -PLA was reported to be 30–60 °C higher than that of individual PLLA and PDLA, which is attributed to the close packing of polymer chains, strong intermolecular interactions and consequently increased crystallinity [38,39,40,41] As shown in Figure 3a, the blends containing more than 5 wt % of sc -PLA show only one melting point at about 215 °C. This indicates electrostatic field applied in ESB process favor the formation of sc -PLA in PMMA nanofibers and is beneficial to improve the miscibility of sc- PLA and PMMA under certain conditions of sc -PLA content [42].…”

Poly(Lactic Acid) Blends

“…Solution blends prepared from solution/precipitation with THF/hexane were miscible with q of À87 and evidence of hydrogen bonding determined from FTIR [53,54]. The phase behavior, interactions, and crystallinity of ternary blends of PVPh (M w ¼ 22 kDa) with PLLA (M w ¼ 152 kDa) and poly(D-lactic acid) (PDLA) (M w ¼ 124 kDa) at weight ratios of 2/49/49, 5/47.5/47.5, 10/45/45, and 20/40/40, prepared by solution casting from dioxane, were investigated [55]. The ternary blends exhibited one T m around 220 C (belonging to stereocomplex PDLA), a single composition-dependent T g (close to PLA), and a single composition-dependent T c (belong to a stereocomplex PDLA) that increased with augmented PVPh content.…”

“…The addition of a small amount of PVPh (up to 10 wt%) also enhanced the crystallization rate and reduced the spherulite size of stereocomplex PLDA. However, the addition of a high amount of PVPh may lead to phase separation in PVPh/PLLA/PDLA blends [55].…”

Composite banded core and non-banded shell transition patterns in stereocomplexed poly(lactide acid) induced by strongly interacting poly(p-vinyl phenol)

“…[13][14][15] The miscible PEO component was believed to induce re-orientation of lamellae, resulting in ring-banded spherulites, as shown in a previous study. 21 The addition of another polymer to sc-PLA was reported to inuence the crystallization behavior 19,21 and improved the processability and thermomechanical properties of sc-PLA. On the other hand, PDLA has been reported to a lesser extent to form ring-banded spherulites either in neat conditions or while blending with another component.…”