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

Abstract

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. POLYM. COMPOS., 40:2617–2628, 2019. © 2018 Society of Plastics Engineers

Improving the Oxygen Barrier of Polyamide Food Packaging by Using Nanoclay

“…The disappearance of this peak by transmission XRD and appearance by reflection XRD analysis confirms the assumption about the preferential orientation of clay crystallites in the PAnanoclay composite. Abdelwaha et al [16] observed a similar preferred orientation effect for polyamide-Nanomer I.30T composite produced by melt extrusion and injection molding, and explained the different behavior of basal reflection measured in reflection and transmission modes of XRD pattern by the anisotropic effect of the injection molding forcing the nanoclay platelets to be oriented preferentially parallel to the plane of the samples.…”

“…Approximately a triple increase of the broadening of this reflection from 1.1° to 3.1°, that corresponds to decrease of the effective X-ray crystallite size from 6.4 nm to 2.6 nm, or decrease of the average number of clay layers in [001] direction of the crystallites from 3 to 1.7, was observed for the nanoclay in the composite. This result can be explained by the appearance of partially exfoliated crystallites of nanoclay in the composite, but might also indicate an unevenly delaminated or polymer intercalation and gradients in d-spacings of the clay crystallites [16]. The low intensity of this reflection, related to the low concentration of partially exfoliated clay crystallites in the composite, allowed us to infer that the concentration of intercalated nanoclay crystallites is small and most of the silicate layers of crystallites in the nanocomposite were exfoliated or delaminated.…”

A review of high performance polymer nanocomposites for packaging applications in electronics and food industries

“…However, polymer nanocomposites are usually in intercalated and/or exfoliated form. 45–48 These morphologies are advantageous for improved mechanical properties and barrier properties. Polymer/nanoclay nanocomposite has gained interest in food packaging applications.…”

Subcritical gas‐assisted processing of ethylene vinyl alcohol + nanoclay composites

“…Equibiaxial extensional flows are especially efficient for this purpose because the associated material viscosity is six times greater than the shear case . Improved dispersion of nanocomposite fillers using continuous polymer processing techniques especially melt extrusion has possessed a great interest in recent years . This cost‐effective technology assisted with atmospheric gases is able to produce nanocomposites with enhanced properties for many applications such as electromagnetic interference shielding, sensor applications, and high‐performance polymers …”

“…[28][29][30][31][32][33] Improved dispersion of nanocomposite fillers using continuous polymer processing techniques especially melt extrusion has possessed a great interest in recent years. [33][34][35] This cost-effective technology assisted with atmospheric gases is able to produce nanocomposites with enhanced properties for many applications such as electromagnetic interference shielding, sensor applications, and highperformance polymers. [36][37][38] In this work, EVOH was compounded with NC at a loading of 5% by weight using traditional TSE or SGAP with N 2 or CO 2 as the blowing agent.…”