Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol) : mechanical, thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG-200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (Tg). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG-200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG-200 effectively lowers Tg as well as cold-crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG-200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA

Influence of plasticizers on thermal properties and crystallization behaviour of poly(lactic acid) films obtained by compression moulding

[EN] Neat and plasticized poly(lactic acid) (PLA) films were obtained by compression moulding. Three different plasticizers, at concentrations of 5 and 10%, were used: poly(ethylene glycol) (PEG) of 1000 and 4000gmol(-1) molecular weights and a commercial plasticizer, Palamoll (R) 638. Crystallization behaviour and glass transition of PLA films were analysed using differential scanning calorimetry and X-ray diffraction. Films were also characterised in terms of structural, tensile, barrier and optical properties. The addition of the three plasticizers reduced the glass transition temperature (T-g) while promoting the crystallization of PLA in the compression-moulded films, depending on their type and concentration. PEG 4000 enhanced the crystallization more than PEG 1000 and Palamoll (R) 638, the latter being that which induced the lowest degree of crystallization. The T-g value of the PLA amorphous phase was reduced by the addition of plasticizers, proportionally to their concentration. Nevertheless, all of the plasticized films exhibited similar elastic modulus and were less resistant to break and less extensible due to the greater induced crystallinity. PEG 4000 markedly reduced the film stretchability whereas this effect was less marked when Palamoll (R) 638 was used. (c) 2016 Society of Chemical IndustryMuller, J.; Jiménez Marco, A.; González Martínez, MC.; Chiralt, A. (2016). Influence of plasticizers on thermal properties and crystallization behaviour of poly(lactic acid) films obtained by compression moulding. Polymer International. 65(8):970-978. doi:10.1002/pi.5142S97097865

Effect of plasticizers on thermal and physical properties of compression-moulded poly[(3-hydroxybutyrate)-co- (3-hydroxyvalerate)] films

[EN] Poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] (PHBV) is a promising bio-based, biodegradable polymer for replacing synthetic polymers, but its brittleness limits its application range. With the aim of improving the mechanical properties of PHBV films, different plasticizers (polyethylene glycol (PEG 200, 1000 and 4000), lauric acid (LA) and stearic acid (SA)) were incorporated into the film formulation at 10 wt%. All plasticized films showed lower melting temperature and crystallization degree than pure PHBV films. All plasticizers, except SA, reduced film stiffness and resistance to break, and increased the films¿ water sorption capacity and solubility as well as their water vapour permeability, but only PEG1000 yielded more extensible films. PEG1000 and PEG4000 gave rise to the most heat-resistant plasticized films, while LA and SA highly promoted the heat-sensitivity of PHBV. PEG1000 was the most effective at plasticizing PHBV films, and it was the only plasticizer that partially mitigated the ageing effects. However, a greater ratio of plasticizer would be required to adapt PHBV mechanical properties to some packaging requirements.The authors thank the Ministerio de Economia y Competitividad - Government of Spain for the financial support provided through AGL2013-42989-R Project. Author Raquel Requena thanks the Ministry of Education, Cultural and Sport - Government of Spain for a FPU Grant.Requena-Peris, R.; Jiménez Marco, A.; Vargas, M.; Chiralt, A. (2016). Effect of plasticizers on thermal and physical properties of compression-moulded poly[(3-hydroxybutyrate)-co- (3-hydroxyvalerate)] films. Polymer Testing. 56:45-53. doi:10.1016/j.polymertesting.2016.09.022S45535

Properties of linear poly(lactic acid)/polethylene glycol blends

Poly(lactic acid) (PLA) has great potentials to be processed into films for packaging applications. However, film production is difficult to carry out due to the brittleness and low melt strength of PLA

Physical and rheological properties of plasticized linear and branched PLA

Extrusion of Poly(lactic acid) (PLA) is difficult to carry out due to the brittleness and low melt strength of PLA. In this investigation, linear Poly(lactic acid) (L-PLA) and branched (B-PLA) were plasticized with poly(ethylene glycol) (PEG) having $M_w$ of 1,000 g/mol in various PEG concentrations (0, 5, 10, 15 and 20 wt%). In addition rheological, thermal and mechanical properties were also investigated in this study. In relation to the plasticizer content, dynamic rheological studies showed that the plasticized linear and branched PLA with higher PEG loading have lower viscosity and elastic properties than that of pure PLA. Storage modulus decreased with PEG loading at all frequencies and exhibited weak frequency dependence with increasing PEG content. As expected, plasticizing both linear and branched PLA lowered the glass transition temperature and modified the crystallization characteristics. Moreover, the toughness was increased by plasticizing up to 15 wt% of B-PLA and up to 10 wt% of L-PLA. However, there was decreasing in toughness due to phase separation of PEG phase in the PLA matrix at 20 wt% and 15~20 wt% of B-PLA and L-PLA, respectively. Therefore, the combination usage of branching and plasticizing showed the better properties both the melt stability and the ability to plastic deformation of PLA to meet the requirements for further

Melt strength modification of poly(lactic acid) blends for packaging film production

This research explores the possibility of improving PLA's properties to satisfy and extend its processing applications such as in blown film production. Branched PLA (B-PLA) and linear/branched PLA (L,B-PLA) samples were blended with polyethylene glycol (PEG) with Mw of 1,000 g/mol, as a plasticizer, in various PEG concentrations (0, 5 and 10 wt%). Melt strength measurement by Rheotens experiment was used to verify the possibility of using some of those blends for packaging film production by blown film extrusion. The results showed that the neat B-PLA and L,B-PLA exhibited similar level of melt strength properties. The increase of PEG content decreased the melt strength values, but increased the drawability. The L,B-PLA system showed greater strain hardening behaviour than B-PLA system. Hence, the most beneficial composition (L,B-PLA with 10 wt% of PEG) was used to produce film at varying blow-up ratios of the bubble at 2.5:1 and 3.2:1. It was found that blending of linear and branched PLA, with the addition of PEG as a plasticizer, can be tailored to meet the requirements for film manufacturing as well as the achievement in film extensibility