Home About us Contact
|
Home About us Contact | ||
|
|
||
Alternating Poly (alternating + poly)
Selected AbstractsAlternating poly(ester amide)s from succinic anhydride and ,,,-amino alcohols: synthesis and thermal characterization,,POLYMER INTERNATIONAL, Issue 10 2003Thomas Fey Abstract Alternating poly(ester amide)s 6a,e from succinic anhydride and ,,,-amino alcohols H2N,(CH2)x,OH (x = 2,6) 2a,e were obtained in two steps: ,-carboxyl-,-hydroxy amides 3a,e were prepared from the starting materials in a highly selective reaction, followed by a polycondensation reaction. 1H and 13C NMR analyses of the poly(ester amide)s clearly reveal the alternating microstructure. The poly(ester amide)s with homologous ,,,-amino alcohols H2N,(CH2)x,OH (x = 2,6) are semi-crystalline materials, their melting points show the odd/even effect observed for [n]-polyamides and [n]-polyurethanes. Heating the poly(ester amide)s 6a,e yields the corresponding N -(hydroxyalkyl) imides 4a,e with no trace of cyclic ester amides. Theoretical calculations revealed that the cyclic ester amides 5a,e are clearly richer in energy than the isomeric N -(hydroxyalkyl) imides. These results show that cyclic ester amides can not be prepared from N -(hydroxyalkyl) imides by ring-enlargement reactions. Copyright © 2003 Society of Chemical Industry [source] Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity rangeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Guillaume Frutsaert Abstract New alternating copolymers comprising a chlorotrifluorinated backbone and imidazole-terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton-conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three-step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI-alt-CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi-alt-CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi-alt-CTFE) with sPEEK lies in the range of 4,10 mS cm,1 at 40,70 °C and, for blend membranes rich in poly(Imi-alt-CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223,231, 2010 [source] Essential work of fracture (EWF) analysis for compression molded alternating poly(propylene carbonate)POLYMER ENGINEERING & SCIENCE, Issue 3 2004K. L. Fung In this investigation, the main objective was to study the mechanical properties of alternating poly(propylene carbonate) copolymer (PPC). The PPC used in this study was derived from propylene oxide and carbon dioxide using zinc glutarate as catalyst. The molecular weight of the PPC copolymer used in this study has M,n,33,000. The synthesized PPC was compression molded into sheets of thickness ,1mm. The fracture toughness of the PPC films was determined using the essential work of fracture (EWF) technique, at a laboratory temperature of 20°C, and a loading rate of 1 mm/min. During the EWF measurement, a significant amount of plastic deformation has taken place around the initial ligament region. The measured specific total fracture work (wf) was observed to vary in a linear fashion with the specimen ligament (l), and hence satisfied the basic requirement for EWF analysis. The specific essential fracture work (we) for the PPC film was measured to be 11.0 kJ/m2. The PPC showed a prominent recovery behavior. The severely deformed region surrounding the fracture ligament was observed to recover completely 8 days after fracture testing. Polym. Eng. Sci. 44:580,587, 2004. © 2004 Society of Plastics Engineers. [source] Thermally stable and high molecular weight poly(propylene carbonate)s from carbon dioxide and propylene oxide,POLYMER INTERNATIONAL, Issue 10 2002Q Zhu Abstract The copolymerization of carbon dioxide and propylene oxide was carried out to afford alternating poly(propylene carbonate) in high yield. Thermal stable and high molecular weight copolymers were successfully obtained by optimizing the reaction conditions. The catalyst used was zinc glutarate supported on a perfluorinated compound containing 7,12 carbon atoms. Copolymerization parameters, such as the ratio of propylene oxide to catalyst, stirring strength and purity of propylene oxide, were studied. The alternating copolymer with a molecular weight of 56,100 in a very high yield (126,g polymer per gram of catalyst) was achieved, which is the highest yield ever reported. The thermal and mechanical properties of the alternating PPC copolymer were examined by the means of modulated differential scanning calorimetry (MDSC), thermogravimetric analysis (TGA) and tensile test. MDSC and TGA results showed that the alternating PPC copolymer exhibits an extremely high glass transition temperature (maximum 46.46,°C) and decomposition temperature (255.8,°C) when compared to those values reported in literature. Tensile test revealed that thin film of alternating PPC copolymer exhibits superior mechanical strength. © 2002 Society of Chemical Industry [source] | ||||||||||