Modification of Brittle Polylactide by Novel Hyperbranched Polymer-Based Nanostructures

Abstract

The inherent brittleness of polylactide (PLA) poses considerable scientific challenges and limits its large-scale applications. Here, we propose and demonstrate a new industrially relevant methodology to develop a polylactide (PLA)-based nanoblend having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyperbranched polymer (HBP) was in-situ cross-linked with a polyanhydride (PA) in the PLA matrix during melt processing. There was formation of new hyperbranched polymer-based cross-linked particles in the PLA matrix. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) revealed the sea-island morphology of PLA-cross-linked HBP blend. The domain size of cross-linked HBP particles in the PLA matrix was less than 100 nm as obtained from TEM. The presence of cross-linked hyperbranched polymer in the PLA matrix exhibited ∼570% and ∼847% improvement in the toughness and elongation at break, respectively, as compared to unmodified PLA. The increase in the ductility of modified PLA was related to stress whitening and multiple crazing initiated in the presence of cross-linked HBP particles. Formation of a networked interface as revealed by rheological data was associated with enhanced compatibility of the PLA-cross-linked HBP blend as compared to the PLA/HBP blend. The cross-linking reaction of HBP with PA was confirmed with the help of Fourier transform infrared spectroscopy (FTIR) and low-temperature dynamical mechanical thermal analysis (DMTA).

Modification of poly(lactic acid)/poly(propylene carbonate) blends through melt compounding with maleic anhydride

“…Correspondingly, its SEM micrograph exhibits intensive plastic deformation (Figure 4b), indicating the presence of large deformation in the blend. The rough fracture surface suggesting that the cracking propagation absorbs considerable amount of strain energy before failure [33]. And the addition of MA increases the interfacial adhesion between PLA and PPC components, leading to a significant improvement in toughness.…”

Modification of Lignin with Silane Coupling Agent to Improve the Interface of Poly(L-lactic) Acid/Lignin Composites

“…Degradable bio-composites can be broadly defined as composite materials consisting of natural fillers and biopolymers such as poly(ε-caprolactone), poly(lactic acid), or polyhydroxyalkanoates (Chun et al 2012). Poly(lactic acid) (PLA), which is a racemic mixture, is one of the most promising biopolymers commercially available today (Li et al 2003;Bhardwaj and Mohanty 2007). It is primarily produced via the ring-opening polymerization of lactides, which themselves are derived from agricultural products such as corn, beet, or rice (Yao et al 2011).…”

The Innovation Research of Biodegradable Polymers for Sustainable Packaging

“…Unfortunately, although most physical properties are equivalent to the engineering plastics, the current incorporation of PLA into large-scale commercial applications has been greatly restricted by several disadvantages, such as its low thermal resistance, inherent brittleness, and poor water-vapor barrier properties [13,14,15]. The use of natural fibers as fillers or reinforcing agents and other biodegradable polymers (for example, starch and protein) in PLA blends or composites is expected to considerably lower the price of the products as well as to improve the properties without compromising the biodegradability [13,16] Richard Eungkee Lee et al [12] manufactured PLA foam sheets with two-layered structures by laminating a solid high heat deflection temperature (HDT) PLA film onto a low density PLA foam sheet, which is able to increase the thermoformed foam products' service temperatures and to satisfy the requirements in hot-fill food packaging applications.…”