Thermal characterization of phenol and bisphenol-A based polybenzoxazines

Download

index.pdf

Date

2009

Author

Bagherifam, Shahla

Metadata

Show full item record

Item Usage Stats

224
views

85
downloads

Although, several researches on synthesis and characterization of benzoxazines and polybenzoxazines have appeared in the literature, detailed studies on thermal characterization are still limited. In this study, polymerization and thermal degradation mechanisms of benzoxazines were investigated via direct pyrolysis mass spectrometry. Benzoxazine monomers prepared by reactions of phenol or bisphenol- A with aniline or methyl amine were analyzed to investigate the effects of the structures of phenyl and amine groups on both polymerization and thermal degradation behaviours. It has been proposed in the literature that polymerization of benzoxazines occurs by ring opening polymerization of oxazine ring; cleavage of O-CH2 bond of the oxazine ring and attack of n-CH2 group to phenol or bisphenol-A ring. However, the direct pyrolysis mass spectrometry analyses of polymerization and thermal degradation of benzoxazines pointed out that after the cleavage of O-CH2 bond of the oxazine ring, polymerization proceeded through opposing pathways. Strong evidences confirming coupling of (CH3)NCH2 or (C6H5)NCH2 groups yielding dimers involving diamine linkages were detected. Polymerization of the dimer by the reactions with the corresponding monomers was proposed. In case of benzoxazines based on bisphenol-A, the results indicated polymerization of the dimer ii by coupling of both of the oxazine rings. On the other hand, polymerization of the dimer through the ethylene units (vinyl polymerization) in case of benzoxazine monomer based on phenol and methyl amine was also noted. For polybenzoxazines based on aniline another polymerization pathway involved attack of radicals generated by cleavage of the oxazine ring to aniline ring. Multi-step thermal decomposition was observed for all the polybenzoxazines under investigation confirming the presence of units with different structures and stabilities.

Subject Keywords

Polymers.

URI

http://etd.lib.metu.edu.tr/upload/12610409/index.pdf
https://hdl.handle.net/11511/18458

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Polymerization and polymer characterization of n-vinylcaprolactam Polat, Özlem; Usanmaz, Ali; Department of Polymer Science and Technology (2005) In this study, N-vinylcaprolactam was polymerized by radiation in the solid state. The polymerization was carried out at room temperayure under vacuum and open to atmosphere respectively. The polymerization mechanism showed autoacceleration and the rate of polymerization was higher in the presence of oxygen. However the limiting conversion was 100% under vacuum conditions and 90% in the present of oxygen. This is due to the low molecular weight olgomer formation in the presence of oxygen. The polymers were ...
Structural and thermal characterization of polymers via pyrolysis mass spectrometry Argın, Emir; Hacaloğlu, Jale; Department of Chemistry (2005) In the first part of this study, the structtural and thermal characterization of electrochemically and chemically polymerized poly(paraphenylene vinylene), (PPV), have been investigated by direct pyrolysis mass spectrometry. Thermal characteristics, and degradation products of electrochemically prepared poly(paraphenylene vinylene). Pyrolysis study indicated that thermal decomposition of PPV occurs at least two steps. The first being due to the loss of supporting electrolyte present and the second being dec...
Pyrolysis mass spectrometric analysis of copolymer of polyacrylonitrile and polythiophene Oğuz, Gülcan; Hacaloğlu, Jale; Department of Polymer Science and Technology (2004) In the first part of this work, the structural and thermal characteristics of polyacrylonitrile, polyacrylonitrile films treated under the electrolysis conditions in the absence of thiophene, polythiophene and the mechanical mixture and a conducting copolymer of polyacrylonitrile/polythiophene have been studied by pyrolysis mass spectrometry technique. The thermal degradation of polyacrylonitrile occurs in three steps; evolution of HCN, monomer, low molecular weight oligomers due to random chain cleavages a...
Electrochemical synthesis of new conjugated polymers based on carbazole and furan units Oguzturk, H. Esra; TİRKEŞ, SEHA; Önal, Ahmet Muhtar (2015-08-01) In this study, synthesis of four new monomers; 3,6-di(2-furyl)-9H-carbazole (M1), 3,6-di(2-furyl)-9-ethyl-carbazole (M2), 2,7-di(2-furyl)-9-H-carbazole (M3), 2,7-di(2-furyl)-9-(tridecan-7-yl)-9H-carbazole (M4), was achieved via Stifle cross-coupling reaction. The monomers were electrochemically polymerized, via repetitive cycling in acetonitrile-tetrabutylammonium hexafluorophosphate electrolytic medium. Optical and electrochemical properties of the monomers and their corresponding polymers were investigate...
Nanocomposites based on blends of polyethylene Işık, Fatma; Yılmazer, Ülkü; Department of Chemical Engineering (2005) In this study the effects of compatibilizer type, organoclay type, and the addition order of components on the morphological, thermal, mechanical and flow properties of ternary nanocomposites based on low density polyethylene, LDPE were investigated. As compatibilizer, ethylene/methyl acrylate/glycidyl methacrylate, ethylene/glycidyl methacrylate, and ethylene/butyl acrylate/maleic anhydride; as organoclay Cloisite? 15A, Cloisite? 25A and Cloisite? 30B were used. All samples were prepared by a co-rotating t...

Citation Formats

S. Bagherifam, “Thermal characterization of phenol and bisphenol-A based polybenzoxazines,” M.S. - Master of Science, Middle East Technical University, 2009.