Thesis
The role of zinc ionomer in the impact performance of polylactide (PLA) ternary blends: Effect of acid content and degree of neutralization
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/100784
Abstract
In this work, polylactide (PLA) was blended with an epoxy-containing elastomer (ethylene/n-butyl acrylate/glycidyl methacrylate, ‘EBA-GMA’), and a zinc ionomer (partially neutralized ethylene/methacrylic acid copolymer, ‘EMAA-Zn’). Un-neutralized ethylene/methacrylic acid copolymers (EMAA-H) were used in the place of EMAA-Zn ionomers as controls. In order to study the effect of acid content and degree of neutralization of zinc ionomer on the impact behaviors of the PLA/EBA-GMA/EMAA-Zn (or EMAA-H) ternary blends, EMAA-Zn with various degree of neutralization were derived from two types of EMAA-H containing 15 wt% and 4 wt% methacrylic acid (MAA) comonomer, respectively. Degree of neutralization of EMAA-Zn was determined by Fourier transform-infrared (FT-IR) spectroscopy. The concentration of zinc oxide incorporated into the ionomers was characterized by thermogravimetric analysis (TGA). The mechanical properties of the blends were studied by notched Izod impact tests and tensile tests and the fracture surfaces were investigated by scanning electron microscopy (SEM). Two important reactions involved in the processing of the PLA/EBA-GMA/EMAA-Zn (or EMAA-H) ternary blends, i.e. the interfacial compatibilization between EBA-GMA and the PLA matrix and the crosslinking reaction of EBA-GMA, were studied. Interfacial compatibilization reaction between the epoxy functionalities of EBA-GMA and the terminal hydroxyl groups of PLA was studied using FT-IR. Crosslinking reaction of EBA-GMA in the presence of EMAA-Zn (or EMAA-H) was investigated by torque rheology and its crosslinking level was studied using dynamic mechanical analysis (DMA). The particle size and substructure of the dispersed domains were analyzed using images acquired from transmission electron microscopy (TEM). It was found that neutralization was necessary for the blend to have superior impact strength. The impact strength of blends containing EMAA-Zn with high initial content of MAA were universally higher than that of blends containing EMAA-Zn with low initial content of MAA, regardless of the neutralization degree. The results of this study implied that a good interfacial adhesion between dispersed particles and the PLA matrix, a proper crosslinking level of the EBA-GMA phase and a fine particle size were favorable for high impact toughness of these PLA/EBA-GMA/EMAA-Zn ternary blends.
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Details
- Title
- The role of zinc ionomer in the impact performance of polylactide (PLA) ternary blends
- Creators
- Wenjia Song
- Contributors
- Jinwen Zhang (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525004301842
- Language
- English
- Resource Type
- Thesis