Column fractionation of partially stereoregular poly(propylene oxide)

Alyürük, Kemal
Hartani, Khaled
A column packed with glass beads has been used to fractionate partially stereoregular poly(propylene oxide) (PPO). PPO was first crystallized onto the glass beads from isooctane solution by stepwise lowering the column temperature. Each layer of PPO, which was deposited at different temperature ranges, was extracted by washing the beads with several columns full of isooctane. Thus several fractions differing in both stereoregularity and molecular weight were obtained by progressively increasing the extraction temperature and the solvent residence time in the column. It is concluded that in the procedure described above PPO can be fractionated on the basis of structural and steric regularity. The observed steady increase in the molecular weight of fractions with extraction temperature was interpreted as being due to the fact that the stereoregularity of chains increases with their molecular weight.


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...
Stereoregularity of fractionally crystallized poly(propylene oxide) samples by 13C-NMR spectroscopy
Alyürük, K.; Alyürük, Kemal (Wiley, 1989-4)
Several stereoregular poly(propylene oxide) (PPO) samples were synthesized employing either trimethyl aluminum hydrolyzates or Pruitt–Baggett type catalysts. Dilute isooctane solutions of these samples were fractionally crystallized by stepwise cooling from 333 K down to 273 K. The fractions which dissolve at 273 K were noncrystallizable and were further fractionated by GFC. The isolated fractions were characterized by 13C‐NMR, DSC, and viscometry techniques. Both structural (head‐to‐head and tail‐to‐tail l...
Characteristics of dual-type electrochromic devices based on poly(ethylene oxide) copolymers
Yildiz, Huseyin Bekir; Sahin, Elif; Çırpan, Ali; Toppare, Levent Kamil; Yagci, Yusuf (Wiley, 2007-05-01)
Dual-type polymer electrochromic devices based on [(3-thienyl)methylmethacrylate]-co-[p-vinyl benzyloxy poly(ethylene oxide)]/polythiophene and thiophene-capped poly(ethylene oxide)/polythiophene and ethylene dioxythiophene were constructed via electropolymerization. Spectroelectrochemistry, switching ability and stability of the devices were investigated using UV-visible spectrophotometry and cyclic voltammetry. These devices exhibit low switching; voltages and short switching times with reasonable switchi...
Synergistic effect of boron containing substances on flame retardancy and thermal stability of clay containing intumescent polypropylene nanoclay composites
Dogan, Mehmet; Bayramlı, Erdal (Wiley, 2011-12-01)
The functions of nanoclay and three different boron containing substances, zinc borate (ZnB), borophosphate (BPO(4)), and boron silicon containing preceramic oligomer (BSi), were studied to improve the flame retardancy of polypropylene (PP)-nanoclay-intumescent system composed of ammonium polyphosphate (APP) and pentaerythritol (PER). The flame retardancy of PP composites was investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA), and cone calorimeter.
Ratiometric fluorescence detection of an anthrax biomarker with Eu3+-chelated chitosan biopolymers
Donmez, Mert; Öktem, Hüseyin Avni; Yilmaz, M. Deniz (Elsevier BV, 2018-01-15)
A novel chitosan-based ratiometric fluorescent probe incorporating an EDTA-Eu3+ complex as the sensing unit and fluorescein dye as the internal standard was designed to detect dipicolinic acid (DPA) as an anthrax bio-marker with high sensitivity and selectivity. The fluorescence intensity of fluorescein dye attached to the chitosan backbone remains constant as an internal reference, while the Eu3+ emission increased linearly upon the consecutive addition of DPA. The selectivity studies were performed by add...
Citation Formats
K. Alyürük and K. Hartani, “Column fractionation of partially stereoregular poly(propylene oxide),” Polymer, pp. 2328–2331, 1989, Accessed: 00, 2020. [Online]. Available: