Morphology Development via Static Crosslinking of (Polylactic Acid/Acrylic Rubber) as an Immiscible Polymer Blend

• Published in: Macromolecular materials and engineering Vol. 303; no. 3
• Main Authors: Hesami, Mahdis, Jalali‐Arani, Azam
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.03.2018
• Subjects: Acrylic rubber; Atomic force microscopy; Biodegradable materials; Crosslinking; Curing agents; Fourier transforms; immiscible blend; Infrared spectroscopy; Microscopy; Morphology; Optical microscopy; Polylactic acid; Polymer blends; Rheological properties; Rheology; Spectrum analysis; static crosslinking; viscoelastic properties; Viscoelasticity; Vulcanization
• ISSN: 1438-7492; 1439-2054
• DOI: 10.1002/mame.201700446

The interrelation between crosslinking and morphology is investigated for an immiscible blend of polylactic acid (PLA) and acrylic rubber (ACM). The blends are prepared by solution mixing and static crosslinking is used to avoid the simultaneous effect of the flow field that occurs in dynamic vulcanization. It is carried out at different temperatures, times, and curing agent contents. Scanning force microscopy (SFM) and polarized optical microscopy are used to determine the morphology of the blends. The chemical interactions and viscoelastic properties of the blends after crosslinking are also studied using infrared spectroscopy and rheological tests, respectively. Before crosslinking, SFM shows matrix‐droplet morphology for the samples that it is retained after that for the blend with 30 wt% ACM; however, it is changed to cocontinuous one in the blend with 50 wt% ACM. Partially, grafting of PLA on the crosslinked ACM is confirmed by Fourier transform infrared spectroscopy. The rheological results show that the incorporation of ACM to the PLA slows down the chain relaxation and vulcanization intensifies this effect. A model is proposed to explain the morphology evolution during static crosslinking of an immiscible blend. Static crosslinking of polylactic acid (PLA)/acrylic rubber (ACM) as an immiscible polymer blend is studied. Before crosslinking, a matrix‐droplet morphology is observed for the samples that after crosslinking is changed to a cocontinuous one in the blend with 50 wt% ACM. It is explained by formation of a self‐generated elastic force. In addition, a partially grafting of PLA chains on the ACM is detected.