Ternary polymer blends based on poly(lactic acid): Effect of stereo‐regularity and molecular weight

Abstract

The effects of stereo‐regularity and molecular weight of poly(lactic acid) (PLA) on ternary polymer blends was analyzed using optical clarity as the primary screening method. This enabled the ready identification of phase boundaries of optically clear and apparently miscible regions. Solvent‐mediated blends of amorphous poly(dl‐lactide) (PDLLA) and semi‐crystalline poly(l‐lactide) (PLLA) with various molecular weights from high to low, along with polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were used in this study. The nature and extent of crystallinity of the blends was examined by X‐ray diffraction, which, in conjunction with differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy, provided information about the competition between polymer crystallization (self‐aggregating behavior) and intermixing of the macromolecules. Thus, allowing the primary physical cause of transparency loss to be identified. The results of the ternary blends optical clarity showed the position of the phase boundaries in PLLA/PCL/CAB and PDLLA/PCL/CAB blends are significantly affected by the stereo‐regularity and molecular weight of PLA. The PDLLA (amorphous) blend shows comparable regions of phase separation with high molecular weight and semi‐crystalline PLLA blends even though the molecular weight is much lower. The blends of the shorter chain PLLA1 tend to show more crystalline regions. The optical transparency, miscibility, and crystallinity of the blends are not only affected by the stereo‐regularity and molecular weight of PLA but also the crystallizable PCL, especially at high loading. These findings give useful information to the film‐packaging sector where good optical clarity is a critical performance requirement. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41780.

Green fabrication route of robust, biodegradable silk sericin and poly(vinyl alcohol) nanofibrous scaffolds

“…Figure shows the FTIR spectra of samples EP1–EP9. All samples show a small shift in amide I and amide II peaks to higher wavenumbers when compared to neat SS, while the broad bands (3700–3000 cm −1 ) of NH stretching of SS and hydrogen‐bonded OH of PVA simply show the spectrum of the two homopolymers, which can be described as a miscible blend . This miscible blend suggests that there are molecular interactions between PVA and SS.…”

Environmentally Friendly Compatibilizers from Soybean Oil for Ternary Blends of Poly(lactic acid)-PLA, Poly(ε-caprolactone)-PCL and Poly(3-hydroxybutyrate)-PHB

“…Due to the low miscibility of PLA with most polymers, the use of compatibilizers and/or reactive extrusion have been proposed as technical solutions to improve compatibility in binary PLA-based blends [ 30 , 33 ]. Moreover, ternary blends with PLA have also given good results in terms of improved toughness as tailored properties can be obtained by selecting the appropriate components and/or compatibilizers [ 24 , 34 , 35 , 36 , 37 , 38 , 39 ].…”

Ternary blend nanofibres of poly(lactic acid), polycaprolactone and cellulose acetate butyrate for skin tissue scaffolds: influence of blend ratio and polycaprolactone molecular mass on miscibility, morphology, crystallinity and thermal properties

“…The miscibility or immiscibility of ternary blend fibres can be investigated using FTIR spectroscopy. If a blend is immiscible, the FTIR spectrum is simply the summation of the spectra of the two or three homopolymers, while shifts in the characteristic bands in the FTIR spectrum indicates a level of miscibility . Figure shows the FTIR spectra of electrospun fibres of the homopolymers (PLA, PCL, CAB) and the blends.…”

“…CAB was chosen because of its known compatibility with ester‐containing polymers, provided by the miscibility prediction between polymer pairs developed by Coleman et al . and our previous researches …”