Compatibility, steady and dynamic rheological behaviors of polylactide/poly(ethylene glycol) blends

Abstract

Understanding the rheological behavior of plasticized polylactide (PLA) contributed to the optimization of processing conditions and revealed the microstructure–property relationships. In this study, the morphological, thermal, steady and dynamic rheological properties of the PLA/poly(ethylene glycol) (PEG) blends were investigated by scanning electron microscope, differential scanning calorimeter, and capillary and dynamic rheometers, respectively. The results illuminated that the melt shear flow basically fitted the power law, whereas the temperature dependence of the apparent shear viscosity (ηa) or complex viscosity (η*) followed the Arrhenius equation. Both the neat PLA and PLA/PEG blends exhibited shear‐thinning behavior. Because the incorporation of PEG reduced the intermolecular forces and improved the mobility of the PLA chains, the ηa, η*, and storage and loss moduli of the PLA/PEG blends decreased. The PEG content (WPEG) ranged from 0 to 10 wt %, both ηa and η* decreased significantly. However, the decrements of ηa and η* became unremarkable when WPEG exceeded 10 wt %. The reason was attributed to the occurrence of phase separation, which resulted in the decrease in the plasticization and lubrication efficiencies. This study demonstrated that the addition of the right amount of PEG obviously improved the flow properties of PLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42919.

Synergistic effects of polyethylene glycol and organic montmorillonite on the plasticization and enhancement of poly(lactic acid)

“…This finding was due to PEG acting as a macromolecular plasticizer and increasing the free volume of polymer chains, which weakened the degree of chain entanglement. However, at 1.5 wt % OMMT, the end of the arc rose, a new Cole–Cole radius emerged, and a new relaxation behavior was found, showing that the single layer of slices formed a rigid inorganic particle network structure …”

The effect of poly(ethylene glycol) mixed with poly(l‐lactic acid) on the crystallization characteristics and properties of their blends

“…Meanwhile, when the PEG‐10000 content was 20 wt%, the most efficient plasticizing effect was obtained. In another study of Li et al ., in which PEG ( M w = 6000 g mol −1 ) was incorporated in PLLA at 5, 10, 15 and 20 wt% via melt‐extrusion, the single glass transition temperature ( T g ) and the significant reductions in T g and cold crystallization temperature ( T cc ) of the PLLA/PEG blends demonstrated that PEG was miscible with PLLA when the PEG content was less than 10 wt%. By comparing the small melting peaks of PEG observed in the PLLA/PEG blends when PEG was incorporated at 15 and 20 wt% to that of pure PEG, it was suggested that the PEG phase might have been separated from the PLLA/PEG blends.…”

“…Among the thermoplastic aliphatic polyesters, poly( l ‐lactic acid) (PLLA) presents excellent biodegradability, biocompatibility and bioresorbability along with transparency and low toxicity . Standard‐grade PLLA is also characterized by high modulus and strength but is brittle and rigid in nature with poor toughness and low melt strength which lead to difficulties in demoulding .…”

“…PEG is a linear or branched hydroxyl‐terminated polyether, which is usually prepared by anionic ring‐opening polymerization of ethylene oxide . PEG is an excellent plasticizer for PLLA because it is miscible with it without the need for any compatibilizer and can markedly increase the PLLA elongation at break . Owing to its excellent lubricity, hydrophilicity, good biocompatibility, non‐toxicity, rapid clearance from the body and non‐immunogenicity, PEG has been extensively used in various fields, such as in cosmetics and food processing .…”

Poly (Lactic Acid) Films in Food Packaging Systems

“…Poly (lactic) acid (PLA) is biodegradable aliphatic polyester, which can be fabricated by fermentation of renewable resources such as corn, cassava, potato and sugarcane [1,2]. Comparison to other aliphatic polyesters, PLA has perfect attributes such as high mechanical strength, high modulus, biodegradability, biocompatibility, bio absorb ability, transparency, energy savings, low toxicity and easy process ability [3,4]. Moreover, PLA has a wide range of applications such as in agricultural films, biomedical devices, packaging, and automotive industries due to its great properties [5][6][7].…”