Mechanical and Barrier Properties Enhancement in Film Extruded Bio‐Polyamides With Modified Nanoclay

The plastics industry is increasingly oriented towards the use of bio‐based polymers replacing the fossil‐based ones. Bio‐based polyamides (PAs) in the film packaging application are not still used and need enhancement to overcome some drawbacks. In this scenario, fully (PA10.10) and partially (PA6.10) bio‐based PAs were extruded in a laboratory sheet‐casting machine. The materials used to obtain films were previously melt blended with modified clay in a twin‐screw extruder. The resulting films were morphologically investigated through the scanning electron microscope. The magnifications show agglomerated particles and the packed layers are preferentially aligned in the extrusion machine direction. X‐rays confirm that 5 wt% of clay content is difficult to exfoliate in such matrices. The crystallinity was studied by using X‐ray diffraction (XRD) and differential scanning calorimetry. The XRD results show coexisting α and γ phases in the PA6.10 while the presence of only γ in the PA10.10. The presence of clay platelets constrains the crystallites formation, especially in the more polar PA6.10, resulting in changes in the type and the amount of crystals. The mechanical analysis data showed that 5 wt% of clay induced significant improvement in Young's modulus (+68 and + 14%), a slight increase in the tensile yield stress (+21 and + 5%) and only a surprisingly small decrease in the deformation at break (−15 and −24%) for PA10.10 and PA6.10, respectively. Furthermore, the addition of clay gave the best oxygen barrier properties reaching a value of 1.8 ± 0.2 cm3 × mm/m2 × day × atm comparable to a commercial PA6 film used in the packaging field.