Rheology and extrusion foaming of chain‐branched poly(lactic acid)

Abstract

Rheology and extrusion foaming of chain-branched poly(lactic acid)Mihai, Mihaela; Huneault, Michel A.; Favis, Basil D.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. In this study, the effect of macromolecular chainbranching on poly(lactic acid) (PLA) rheology, crystallization, and extrusion foaming was investigated. Two PLA grades, an amorphous and a semi-crystalline one, were branched using a multifunctional styrene-acrylicepoxy copolymer. The branching of PLA and its foaming were achieved in one-step extrusion process. Carbon dioxide (CO 2 ), in concentration up to 9%, was used as expansion agent to obtain foams from the two PLA branched using chain-extender contents up to 2%. The foams were investigated with respect to their shear and elongational behavior, crystallinity, morphology, and density. The addition of the chain-extender led to an increase in complex viscosity, elasticity, elongational viscosity, and in the manifestation of the strain-hardening phenomena. Low-density foams were obtained at 5-9% CO 2 for semi-crystalline PLA and only at 9% CO 2 in the case of the amorphous PLA. Differences in foaming behavior were attributed to crystallites formation during the foaming process. The rheological and structural changes associated with PLA chain-extension lowered the achieved crystallinity but slightly improved the foamability at low CO 2 content. POLYM. ENG. SCI.,

Biopolymer Blends Based on Poly (lactic acid): Shear and Elongation Rheology/Structure/Blowing Process Relationships

“…Some experiments have been conducted by our team researchers in previous works [5][6][7][8][9][11][12][13]. We showed that the structural modification of PLA highly increased the shear rheological properties (melt strength, zero-shear viscosity, elasticity, shear-thinning behavior) and contributed to very long relaxation process.…”

“…Many strategies have motivated considerable research efforts. In particular, two strategies are presented here: (i) modification of PLA through branched architecture with chain-extension reactions to compensate for the molecular weight decrease caused by the processing degradation [7,8] and (ii) blending PLA with other natural or synthetic materials such as Polycaprolacton (PCL), starch, poly (butylene adipate-co-terephtalate) (PBAT), poly(butylene succinate-co-adipate) (PBSA), etc. [9].…”

The effect of two commercial melt strength enhancer additives on the thermal, rheological and morphological properties of polylactide

“…Najafi et al [21] prepared PLA-clay nanocomposites using polycarbodiimide, tris(nonyl phenyl) phosphate and Joncryl ADR-4368 as chain extenders. Liu et al [16], Corre et al [22], Mihai et al [23] and Pilla et al [24], employed a multi-functional epoxy-based chain extender (Cesa-Extend from Clariant) to give rise to branched structures of PLA. Recently, Han et al [25] used polysilsesquioxane microspheres as novel chain extenders to improve the thermal stability of PLA.…”

Batch Foaming of Amorphous Poly (DL-Lactic Acid) and Poly (Lactic Acid-co-Glycolic Acid) with Supercritical Carbon Dioxide: CO2 Solubility, Intermolecular Interaction, Rheology and Morphology

“…However, there are very few studies about extrusion foaming of PLA (Reignier et al, 2007;Mihai et al, 2010). Mihai et al studied the rheology and extrusion foaming of chainbranched PLA at a temperature between 180 o C to 200 o C (Mihai et al, 2010).…”

“…Mihai et al studied the rheology and extrusion foaming of chainbranched PLA at a temperature between 180 o C to 200 o C (Mihai et al, 2010). Two PLA grades, an amorphous and a semicrystalline one, were branched using a multifunctional styrene-acrylic-epoxy copolymer.…”