Thesis
Investigation of poly(lactic acid)/polyoxy methylene blends: crystallization behavior and heat resistance
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/100540
Abstract
In this research, poly(lactic acid) (PLA)/polyoxymethylene (POM) was prepared through melt extrusion. Crystallizations of neat PLA and PLA in the presence of POM were investigated by differential scanning calorimetry (DSC), polarized optical microscope and X-ray diffraction (XRD) in detail for a comparative study of the effects of different fillers on the crystallization and morphology of PLA. The results suggest that the crystal structure of PLA remained unchanged by the addition of POM, while the crystallization ability of PLA was enhanced in the presence of POM. The PLA/POM blends presented higher light transmittance than neat PLA and the PLA/talc blends, indicating POM was partially miscible with PLA, which was v consistent with the FTIR results. Well-defined banded spherulites were found in the case of PLA/POM blends during isothermal crystallization. The thermodynamic properties and phase morphology were examined using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Heat deflection temperature (HDT) of PLA was improved by incorporating POM, a highly crystalline polymer with excellent heat resistance. The HDT of neat PLA was increased nearly 2-fold from 65.5 oC to 133 oC by adding 50 wt% POM. Multiple-crack structure was observed on the surface of the PLA blends containing high POM content. Fox equation was used to assess the miscibility of the PLA/POM blends and showed that the PLA/POM blends were partially miscible, which was consistent with the FTIR results in which a distinctive characteristic peak around at 1000 cm-1 for PLA/POM blends indicated partially miscible. The toughening effects of two elastomers on the PLA/POM blend (50/50), i.e. thermoplastic polyurethane (TPU) and poly(ethylene-glycidyl methacrylate) (EGMA), were investigated in detail in this study. The experimental results suggested that TPU was more effectively on toughening the PLA/POM blend than EGMA.
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Details
- Title
- Investigation of poly(lactic acid)/polyoxy methylene blends
- Creators
- Xiaojie Guo
- 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
- 99900525180401842
- Language
- English
- Resource Type
- Thesis