Long chain branching polylactide: Structures and properties

Sheets of branched poly(lactic acid) obtained by one step reactive extrusion calendering process: Melt rheology analysis

“…However for modified samples, the terminal zone of the storage modulus is broadened and the transition is shifted to lower frequencies, indicating a longer relaxation process of a better cohesive network formation [29]. As already observed by Liu et al [30], this change of behaviour demonstrates the existence of randomly branched LCB in modified samples. Furthermore, G" shows higher values in the case of the modified samples, indicating an increase in the melt elasticity.…”

“…PLA-2-REX seems to present longer arm lengths than PLA-4-REX due to the more pronounced bump at 60º [31]. As stated by the simulation performed by Liu et al [30] for PLA modified by a Dicumyl peroxide (DCP) samples and the similarity with Figure 8 for the storage modulus shape as well as Figure 9 for the delta shape, small amounts of asymmetric tree-arm star-branched polymers and linear chains in the modified samples may be expected. Based on a technique developed by Honerkamp and Weese [16], the weighted relaxation spectrum "H(") was calculated from the linear relaxation spectrum H(").…”

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

“…Several modification routes have been discussed in the literature in order to create a strain-hardening. Liu et al [14] found that the strain hardening was not observed in PLA without long chain branches (LCB) or even in the PLA with star branched structure. Palade et al [15] reported that the presence of a low fraction of high molecular of PLA makes the strain-hardening occurred.…”

“…Yamane et al, showed that the addition of small amounts of poly(D,L-lactic acid) (PDLA) into PLLA could lead to strain-hardening in poly(L-lactic acid) (PLLA) melts due to the stereocomplex formation acting as branching points on the PLA chains. The effects of chain branching of PLA on foaming ability have been investigated by extensional flow experiment [14,16,17]. The authors found that the chemical chain-extension enhanced the extensional flow of PLA where a relevant strain hardening appeared due to the presence of long chain branches when the macromolecular chain disentanglement rate is too low in relation with the deformation rate.…”

Preparation and properties of multi-branched poly(D-lactide) derived from polyglycidol and its stereocomplex blends

“…The number and types of functional groups on these polymers can be modified to control their properties for specific applications [33]. Recently, multi-branched PLAs have been developed, and their possible applications have been assessed [34][35][36][37][38]. In this work, multi-branched poly(D-lactide)s (mbPDLAs), with different structures and properties, are prepared by employing polyglycidol (PG) as a macro-initiator.…”