Acryloyloxybenzoic acid (ABA) was prepared by the condensation reaction of acryloyl chloride with p-hydroxybenzoic acid in alkaline medium. The polymerization and grafting of ABA onto Polypropylene were anticipated to
occur simultaneously in melt mixing at high temperature. The monomer showed liquid crystalline property. For a better dispersion of ABA in PP before graft copolymerization, a masterbatch of 50-50 (by weight) low density polyethylene
+ ABA was prepared, which was then used for 5, 10, 15 % ABA + PP mixtures in the Brabender Plasti Corder. Furthermore, these compositions were reprocessed at the same temperature in the molten state.
Compression molding was used to prepare films for characterization experiments at 200 º / C under 15000 psi for approximately 3-5 minutes. The graft copolymers were characterized by several techniques / DSC, FTIR, MFI, SEM
and mechanical testing.
In DSC thermograms the crystallization of PP was seen at approximately 160º / C. An endothermic peak was also assigned to grafted PABA at 280º / C .
The incorporation of ABA onto the PP backbone as a graft copolymer (PABA-g-PP) at low percentages results in a possible rearrangement, where tensile strength values increased, while strain decreased. The grafting goes through
thermal radicalic mechanism.
MFI values were found to increase from 8.7 to 16.35 g/10 min at 10 wt % ABA, then decreased to 10.57 g/10 min at 15 wt % ABA. It is most likely that the presence of PABA produced easy orientational flow up to 10 % of ABA, but at 15 % ABA addition caused a slight decrease in MFI.
The tensile test specimens were analyzed by Scanning Electron Microscope. None of the three samples exhibited phase separation. This observation confirms that the graft copolymerization occurrs in a homogenous manner onto PP. The brittle nature of material is observed at all three compositions.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12607915/index.pdf |
| Date | 01 December 2006 |
| Creators | Isik, Buket |
| Contributors | Tincer, Teoman |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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