Characterization and study of solution properties of poly(propylene oxide) synthesized by metal xanthate catalysts

Download

index.pdf

Date

2003

Author

Tarkın, Eylem

Metadata

Show full item record

Item Usage Stats

158
views

0
downloads

Zinc xanthates polymerize propylene oxide into high polymer (PPO) with coordination mechanism. In order to identify structure and stereoisomerisms of this polymer, PPO was subjected to thermal and column fractionation. Obtained fractions were characterized by end-group analysis, cryoscopy, viscometry, IR and 13C-NMR spectroscopy, melting temperature. PPO is composed of a high molecular weight, stereoregular, crystallizable polymer (K-polymer) with low molecular weight (=500 g/mol) D-polymer. Presence of double bonds and hydroxyl terminals was interpreted as the product of an anionic mechanism. K-Polymers can be thermally fractionated on the basis of their melting temperature (Tm) rather than molecular weight (Mwt). It̕s found that higher Tm fractions have lower Mwt, but they precipitate at higher temperatures than higher Mwt but lower Tm fractions. In column fractionation, K-polymers were deposited on glass beads from isooctane solution in a narrow temperature interval. Then the precipitated samples were split into a number of fractions by using again isooctane but at a higher temperature than the precipitation temperature by increasing residence time from 5 minutes to several hours. It̕s found that rate of solubility is not controlled by molecular weight, but controlled by percentage crystallinity and Tm. Highest Tm polymers, with relatively higher Mwt showed faster rate of solution than that of lower Tm, lower Mwt but higher percent crystalline fractions. This discrepancy was accounted by suggesting a stereo-block structure where tactic blocks are bound each other with non-crystallizable atactic blocks. The mechanism of polymerization was also discussed in some detail.

Subject Keywords

Polymers and polymerization, Propylene oxide

URI

http://etd.lib.metu.edu.tr/upload/1086099/index.pdf
https://hdl.handle.net/11511/13448

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Characterization and Electrical Conductivity of Poly(ethylene glycol)/Polyacrylonitrile/Multiwalled Carbon Nanotube Composites Aqeel, Salem M.; Kucukyavuz, Zuhal (Wiley, 2011-01-05) Polymer blends based on poly(ethylene glycol), polyacrylonitrile, and multiwalled carbon nanotubes (MWNTs) were prepared by the solvent cast technique from the dispersion of the MWNTs in the concentration range 0-3.45 wt %. The interaction of the MWNTs with the polymer blend was confirmed by a Fourier transform infrared (FTIR) spectroscopy study. The thermal properties of the polymer blend with the MWNTs were carried out by means of differential scanning calorimetry (DSC). It was evident from DSC that the p...
A density functional theory study of partial oxidation of propylene on Cu2O(001) and CuO(001) surfaces Duzenli, Derya; Atmaca, Deniz Onay; Gezer, Miray Gulbiter; Önal, Işık (2015-11-15) This work theoretically investigates propylene epoxidation reaction on Cu2O(001) and CuO(001) surfaces using periodical DFT method to determine the active copper species within the reaction mechanism. The transition states and energy profiles are calculated for the formation of surface intermediates such as oxametallopropylene (OMP) over Cu2O(0 0 1) and oxygen bridging (OB) over CuO(0 0 1) and allylic H-stripping reaction (AHS) over both surfaces as well as for formation of products. Propylene oxide (PO) an...
Properties of blends prepared from surface-modified low-density polyethylene and poly(vinyl chloride) Akovali, G; Torun, TT (Wiley, 1997-03-01) Improvement of adhesion between low-density polyethylene (LDPE) and poly(vinyl chloride) (PVC) in their blends was attempted by plasma modification of their surfaces. A series of different plasma treatments, vinyl chloride or carbon tetrachloride plasma for PE and acetylene plasma for PVC, were employed. In addition, an oligomeric copolymer of PE-VC was also tested in the blend. After modification, different degrees of improvement were obtained in mechanical properties, ranging from slight for acetylene pla...
Formation and characterization of infrared absorbing copper oxide surfaces Arslan, Burcu; Erdogan, Metehan; Karakaya, İshak (2017-04-30) Copper oxide formation has been investigated to combine the advantages of producing different size and shapes of coatings that possess good light absorbing properties. An aqueous blackening solution was investigated and optimum composition was found as 2.5 M NaOH and 0.225 M NaClO to form velvet copper oxide films. A two-step oxidation mechanism was proposed for the blackening process by carefully examining the experimental results. Formation of Cu2O was observed until the entire copper surface was covered ...
Preparation and characterization of thermally stable organoclays and their use in polymer based nanocomposites Abdallah, Wissam; Yılmazer, Ülkü; Department of Chemical Engineering (2010) The present study was aimed at exploring the purification and modification of montmorillonite rich Turkish bentonites by organic salts and their subsequent effects on the morphology (X-diffractometry, transmission electron microscopy, scanning electron microscopy), melt flow index, mechanical (Tensile, Impact) and especially thermal stability (thermal gravimetric analysis, differential scanning calorimetry) properties of polymer/organoclay nanocomposites with and without an elastomeric compatibilizer. The b...

Citation Formats

E. Tarkın, “Characterization and study of solution properties of poly(propylene oxide) synthesized by metal xanthate catalysts,” M.S. - Master of Science, Middle East Technical University, 2003.