Uniaxial Drawing and Mechanical Properties of Poly[(R)-3-hydroxybutyrate]/Poly(l-lactic acid) Blends

Abstract

Blends of poly(L-lactic acid) (PLLA) with two kinds of poly[(R)-3-hydroxybutyrate] (PHB) having different molecular weights, commercial-grade bacterial PHB (bacterial-PHB) and ultrahigh molecular weight PHB (UHMW-PHB), were prepared by the solvent-casting method and uniaxially drawn at two drawing temperatures, around PHB's T(g) (2 degrees C) for PHB-rich blends and around PLLA's T(g) (60 degrees C) for PLLA-rich blends. Differential scanning calorimetry analysis showed that this system was immiscible over the entire composition range. Mechanical properties of all of the samples were improved in proportion to the draw ratio. Although PLLA domains in bacterial-PHB-rich blends remained almost unstretched during cold drawing, a good interfacial adhesion between two polymers and the reinforcing role of PLLA components led to enhanced mechanical properties proportionally to the PLLA content at the same draw ratio. On the contrary, in the case of UHMW-PHB-rich blends, the minor component PLLA was found to be also oriented by cold drawing in ice water due to an increase in the interfacial entanglements caused by the very long chain length of the matrix polymer. As a result, their mechanical properties were considerably improved with increasing PLLA content compared with the bacterial-PHB system. Scanning electron microscopy observations on the surface and cross-section revealed that a layered structure with uniformly oriented microporous in the interior was obtained by selectively removal of PLLA component after simple alkaline treatment.

Synergistic effect of compatibilizer and cloisite 30B on the functional properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/polylactide blends

“…Regarding publications on PHA/PLA blends reported in the literature, this process was explored as an alternative economical way of achieving novel materials with desired properties [7][8][9][10]. PHA/ PLA polymer blends tend to phase separation due to immiscibility, resulting into poor properties.…”

Effect of multi-walled carbon nanotubes on the crystallization and hydrolytic degradation of biodegradable poly(l-lactide)

“…However, the low toughness, slow crystallization rate and slow degradation rate of PLLA have limited its development and wide practical application; therefore, several modifications have been proposed to overcome the aforementioned problems, such as copolymerization, [2] plasticization, [3,4] polymer blending [5][6][7][8][9][10], and reinforced composites [11][12][13]. Among the several modifications, reinforced composites are regarded as a useful and convenient way to control rate of crystallization and degradation, as well as improve the mechanical properties and the heat resistance.…”

Poly(3-hydroxybutyrate) and biopolymer systems on the basis of this polyester

“…Так, полученный композит ПМК с атПОБ имел меньшую кристалличность, улучшенные механические свойства и большую скорость биодеградации [78]. Были получены и исследованы композиты бактериального ПОБ с ПМК и показано, что они имеют улучшенные механические свойства [80].…”