Blends of high density polyethylene and poly(l‐lactic acid): Mechanical and thermal properties

Abstract

The blends of high‐density polyethylene (HDPE) and poly(l‐lactic acid) (PLLA) were prepared by melt blending method in an extrusion mixer with a postextrusion blown film attachment. The ratios of HDPE/PLLA blends were taken as 100/0, 95/5, 90/10, 85/15, and 80/20. The 80/20 blend was further compatibilized by adding maleic anhydride‐grafted polyethylene in different ratios (up to 8 wt%). Based on the mechanical properties of the films, the compositions HDPE80 (80% HDPE and 20% PLLA) and HD80C4 (80% HDPE, 20% PLLA, and 4% compatibilizer) were found to be optimum and considered for further analysis. The thermal properties of these selected blends were investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA study revealed that the addition of the PLLA somewhat decreased the thermal stability of HDPE. DSC investigation showed that the blends were partially miscible only. X‐ray diffraction (XRD) analysis enlightened that the crystallinity of blends was slightly increased with addition of PLLA. Immiscibility of the two polymers was diminished in the presence of compatibilizer, as indicated by the scanning electron microscopy (SEM) of the blends. These partially biodegradable blends may be used for flexible packaging applications. POLYM. ENG. SCI., 54:2155–2160, 2014. © 2013 Society of Plastics Engineers

Production and investigation of structure and properties of polyethylene–polylactide composites

“…Similarly, the crystallinity of PLA was calculated according to the experimentally determined values enthalpy of PLA Δ H exp ≈ 36.5 J g −1 (Table ) and the reference enthalpy 93.7 J g −1 : …”

“…Similarly, the crystallinity of PLA was calculated according to the experimentally determined values enthalpy of PLA ΔH exp ≈ 36.5 J g −1 (Table II) and the reference enthalpy 93.7 J g −1 : 16,18 Χ cr = ΔH exp =ΔH ref = 36:5=93:7 ≈ 39% Figure 3 shows the DSC curves of the LDPE-PLA composite powder of the different compositions. Three peaks for the LDPE-PLA composite powders at the first heating, regardless of the component ratio, are observed: the glass-transition peak of PLA at 64 C, the melting peak of LDPE at 108-109 C, and the melting peak of PLA at 156 C. This allows one to calculate the crystallinity degree of these polymers, which depends on history of material and production conditions.…”

“…In literature, there are some works on production and investigation of the composites based on PLA and polyethylene . These works are mainly dedicated to the study of the composition effect on the rheological and mechanical properties of the systems under investigation.…”

“…In literature, there are some works on production and investigation of the composites based on PLA and polyethylene. [13][14][15][16][17][18][19][20] These works are mainly dedicated to the study of the composition effect on the rheological and mechanical properties of the systems under investigation. The incompatibility of these polymers was demonstrated 19 via investigation of the morphology of the composites by scanning electron microscopy (SEM) method.…”

Mechanical and morphological properties of high density polyethylene and polylactide blends

“…Even in the case of HDPE and PLLA, because of the difference in their chemical structures, these are immiscible and exhibit weak interfacial adhesion in their binary blends. In order to improve interactions between immiscible polymers, addition of a suitable compatibilizer can increase the morphological stability and interfacial adhesion, and result in better ultimate mechanical properties of the blends [34]. Reactive interfacial coupling agents are frequently used to improve interfacial properties and control morphologies of polymeric blends, as the coupling agents containing reactive functional groups are able to generate in situ formation of grafted copolymers at the interface [35].…”