The Effects of Process Engineering on the Performance of PLA and PHBV Blends

Abstract

The effects of process engineering in the fabrication of PHBV, PLA and their blends prepared by melt blending are studied. The elongation of an optimized blend can be improved by 148 and 250% over the virgin PHBV and PLA polymers, respectively. DSC shows that the two polymers are immiscible in blends of any composition. The crystallinity of PHBV is hindered by the presence of PLA. UV‐Vis demonstrates the opacity of the blend with incorporation of PHBV to the PLA phase. The observed tensile modulus of the optimized sample is compared with theoretical values from the rule of mixtures. Gordon‐Taylor's equation is applied on the glass transition temperatures for theoretical modeling to explain the miscibility of the polymers.

Combined compatibilization and plasticization effect of low molecular weight poly(lactic acid) in poly(lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) blends

“…This gradual decrease of the T g of PLA phase can be understood as an increase of compatibility of PLA/PHBV blends due to the presence of the oLA, miscible with both PLA and PHBV. The cold crystallization temperature of PLA is decreased from 119 to 105°C with the addition of PHBV, as already observed by previous authors [15,16,45], and is not influenced by oLA addition. The PLA degree of crystallinity also remains extremely low in every case (<5%).…”

“…This suggests no complete miscibility between the two polymers [43]. The double melting peak in the range of 147-156°C can be attributed to the formation of different crystal structures for the PLA [16,44]. In the first heating run, characterizing the thermal properties of the films 'as prepared', a slight decrease of the glass transition temperature of PLA from 58°C for the neat PLA film to 56°C for the PLA/PHBV film and 54°C for the PLA/PHBV/oLA 89/10/1 is observed.…”

“…Among polyhydroxyalcanoates (PHAs), which are aliphatic polyesters obtained by microbial fermentation, poly(3-hydroxybutyrate) (PHB) and its copolymers (poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly , poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx)…) have been largely used for PLA-based blends [9]. Some of the resulting blends exhibit improved properties compared to neat PLA: higher toughness and increased elongation at break [10][11][12][13][14][15][16], improved gas barrier properties [17,18], increased thermal stability [16], enhanced biodegradability [14].…”

Packaging related properties of commercially available biopolymers – An overview of the status quo

“…A combination of PHBHB with PLA+filler increases both the WVP and OP significantly. This is probably due to several overlapping effects, for example the effect of the filler and the poorly miscible biopolymers [19,20]. Unfortunately this could not be studied in detail due to the lack of availability of commercial grades.…”

Polylactide/poly(hydroxybutyrate-co-hydroxyvalerate) blends: Morphology and mechanical properties

“…At very low HV content, PHBV is similar to conventional petrochemical thermoplastics, such as polypropylene, in terms of melting temperature, crystallinity, and tensile strength [11][12][13][14][15]. Most of literature agrees on immiscibility of PLA and PHBV [16][17][18][19]. Boufarguine et al [17] created multilayered films of PLA/PHBV (90/10 wt%) using multilayer co-extrusion.…”