Fully bio-based, highly toughened and heat-resistant poly(L-lactide) ternary blends via dynamic vulcanization with poly(D-lactide) and unsaturated bioelastomer

Abstract

Inherent brittleness and low heat resistance are the two major obstacles that hinder the wide applications of poly(L-lactide) (PLLA). In this study, we report a fully biobased, highly toughened and heat-resistant PLLA ternary blend, which was prepared by dynamic vulcanization of PLLA with poly(D-lactide) (PDLA) and an unsaturated bioelastomer (UBE). The results indicated that during dynamic vulcanization PDLA cocrystallized with PLLA to form stereocomplex (SC) crystallites, which not only enhanced the molecular entanglement but also accelerated the crystallization rate of PLLA matrix. With increase in the content of PDLA, the matrix molecular entanglement increased while phase-separation was enhanced, which enabled the impact strength to increase first and then decrease. The ternary blends containing 10 wt.% PDLA showed the highest impact strength. The presence of SC crystallites makes it possible to achieve a fully sustainable PLLA/VUB/PDLA ternary blend with highly crystalline matrix under conventional injection molding, due to the high nucleation efficiency of SC towards crystallization of PLLA. The highly crystalline ternary blend showed excellent heat resistance and better impact toughness than high impact polystyrene.

Rational design of sustainable polyurethanes from castor oil: towards simultaneous reinforcement and toughening

“…The storage moduli of CIPUs are higher than that of COPU and increase with increasing HS content in the full temperature range, indicating reinforced mechanical performance due to the enhanced stiffness. The storage modulus at high temperature can be used to evaluate the heat resistance of a material, because higher storage modulus demonstrates better tolerance to external loading [5,27,28]. The storage modulus of COPU is only 1.59 MPa and the value increases to 2.69, 3.29, 3.54, 13.67, 21.29 and 94.8 MPa for C9I1PU, C8I2PU, C7I3PU, C6I4PU, C5I5PU and C4I6PU, respectively, indicating enhanced heat resistance by incorporation of IS moiety.…”

“…Exploitation of sustainable polymers from renewable feedstocks has attracted increasing attention, due to the continuously increased environmental concerns and resource crisis related to traditional fossil-based polymers [1][2][3][4][5][6]. Inexpensive vegetable oils, with various functional groups such as C=C double bond, ester, hydroxyl and epoxy groups depending on the origins, are thought as the ideal alternatives to fossil resources in production of novel sustainable polymers [7][8][9].…”

Improvement in Mechanical Properties and Heat Resistance of PLLA-b-PEG-b-PLLA by Melt Blending with PDLA-b-PEG-b-PDLA for Potential Use as High-Performance Bioplastics

“…The results suggested that the stereocomplexation of PLLA-PEG-PLLA/PDLA-PEG-PDLA blends improved the heat resistance of the blend films. The heat resistance of PLLA and scPLA has been widely investigated by DMA analysis from storage modulus as a function of temperature [37,38]. The storage modulus of lowcrystallinity PLLA dramatically dropped as the temperature passing the T g region before increasing again due to cold crystallization of PLLA during DMA heating scan.…”

The Effect of Mold Conditions on Heat Resistance of Injection-Molded Stereocomplex Polylactide-b-polyethylene Glycol-b-Polylactide Bioplastic

“…The homo-and sc-crystallites of PLA had melting temperatures at lower and higher than 200 o C, respectively [20]. The scPLA showed better thermo-mechanical properties and heat resistance than PLLA due to faster crystallization of sccrystallites upon cooling [19,21,22]. However, scPLA with high PDLA contents or high content of sccrystallites have to be processed at high temperature (240 − 250 o C) which risks thermal decomposition [12, 23−25].…”