Biphasic polylactide/polyamide 6, 10 blends: Influence of composition on polyamide structure and polyester crystallization. (12th August 2020)

• Record Type: Journal Article
• Authors: Keridou, Ina; Cailloux, Jonathan; Martínez, Juan C.; Santana, Orlando; Maspoch, Maria Lluisa; Puiggalí, Jordi; Franco, Lourdes
• Is Part Of: Polymer. Volume 202(2020)
• Publication Date: 2020-08-12
• Subjects: Epoxy modified polylactide -- Polyamide 6, 10 -- Polyamide/polylactide blend morphology -- Thermal properties -- Polyamide crystalline structure -- Crystal growth rate -- Nucleation; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.122676
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Blends with different ratios of polylactide and polyamide 6, 10 (PA610) have been prepared by melt-mixing using a Brabender mixer equipment. Previously, a rheologically modified polylactide (PLAREx ) was obtained through reactive extrusion using a multifunctional epoxide agent. It was expected that unreacted epoxy groups of PLAREx were able to improve the compatibility between the two polymers. SEM observations revealed a logical dependence of the morphology of immiscible phases with composition, and more interestingly a co-continuity at relatively low PA content (around 50%) was detected. This result contrasts with previous observations performed with non-modified PLA. Confined PA domains increased with the PA content and hardly crystallized at the typical crystallization temperature of the pure PA (195 °C). Synchrotron X-ray diffraction studies indicated that a PA crystallization at a lower temperature close to 120 °C was enhanced and led to a pseudohexagonal γ phase that differs from the characteristic layered structure of PA610. SAXS data revealed also that well differentiated lamellar entities could be assigned at both immiscible polymer phases. Clear differences were observed in the spherulitic morphologies attained under isothermal melt crystallization experiments. Results indicated that the texture of PLAREx spherulites was modified by the presence of PA. Compatibilization of PA molecules on the crystal lamellar boundaries of PLAREx led to an enhancement of the lamellar twisting frequency. Optical microscopy results also indicated that the crystal growth rate of PLAREx increased by the incorporation of PA, but in contrast this had an adverse effect on the nucleation process. Graphical abstract: Image 1 Highlights: Co-continous PLA/PA blend morphology was favoured by employing modified PLA. PLA influenced on the crystalline structure of the polyamide. The crystalline γ-form of polyamide 6, 10 was enhanced in blends due to confinement. Texture of PLA spherulites was influenced by the presence of the polyamide. Polyamide increased the growth rate of PLA but had an anti-nucleation effect.