摘要:

AbstractHighly oriented linear polyethylene was prepared by elongational flow injection molding. The changes in crystal orientation were investigated as a function of temperature by real‐time wide‐angle X‐ray diffraction. Additionally, the influence of molecular weight upon the microstructure and the changes in orientation, during heating near the melting point, and after cooling have been examined. A shish‐kebab structure is inferred for the high molecular weight samples (Mw≥105) from SAXS observations, while for samples with Mw<105only an oriented lamellar structure is found. Consequently, a higher thermal stability is shown by the higher molecular weight samples. Furthermore, a recovery of crystal orientation on rapid cooling of the samples from the melt is only observed for samples with Mw≥105. The results are discussed in terms of a preferential recrystallization of chain‐folded lamellae, on cooling, onto the shish fibrils which survive at hig

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020201

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe mobility of fluorescent probe molecules in the microdomains formed by polyelectrolyte complexes (PEC) in aqueous solution was investigated by the fluorescence polarization method. The degree of fluorescence polarization (p) for the anthracene (Anth) chromophores attached to anionic polyelectrolytes increased with complexation, indicating the restricted mobility of probe molecules in the PEC microdomains. These p values depended on the properties of added polycations, which were not in parallel with the fluorescence intensities of the Anth chromophores.

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020202

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPoly(oxyethylene) (POE) was incorporated into the ionic clusters of ionomers, ethylene and methacrylic acid (7.2% neutralized with KOH) copolymer membrane. The changes of properties were studied from SAXS, DSC, IR and ionic conductivity. The IR study suggested that the coordinated structures in ionic clusters of the membrane were destroyed by POE incorporation, and also SAXS suggested that ionic clusters were swollen by POE incorporation. The ionic conductivity, a carrier being K+in this system, increases from 10−16S/cm to 10−9S/cm at 30°C by the incorporation of POE (20.5 wt%). On the other hand, a large amount of POE (63 wt%) could be incorporated into ionomer membrane by the esterification of methacrylic acid groups (93%) with POE. When LiClO4was added, ionic conduction occurred in the phase‐separated POE domain, which had a low glass transition temperature (−55.2°C), showing an ionic conductivity 2.6 × 10−6

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020203

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractNanocomposites of lead sulfide and several polymers, especially poly(ethyleneoxide), were prepared by coprecipitation of lead sulfide and polymer, followed by a drying and pressing procedure. Such nanocomposites consist of ca. 90% w/w (or ca. 50% v/v) lead sulfide, of particle dimensions of 2–40 nm. The refractive index of these materials is on the order of 3 and therefore, to the authors' best knowledge, is the highest reported for any polymer composit

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020204

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPolyimides are effective thermally stable bonding agents for substrates including titanium, aluminum alloys, steel alloys, metal matrix composites, and polymer/fiber composites with good tolerance toward elevated temperature and humidity.Problems associated with polyimide adhesives, including high processing temperatures and pressures and high melt viscosity, can be partially or totally alleviated by use of blends of polyisoimides. During thermal processing, the polyisoimides are isomerized to their polyimide modifications.

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020205

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPolyethyleneimine (PEIM) samples crosslinked by a commercial epoxy resin (Epon 828) were prepared, and their adsorption capacity for acidic gases was studied. The swelling and deswelling characteristics of the crosslinked samples were also examined as part of this program. Reactivation of these adsorbents could be carried out by heat, or by a combination of heat and treatment in dilute alkalies.

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020206

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractCrosslinked polystyrene microspheres of a diameter of the order of more than 2 μm and a narrow particle diameter distribution were synthesized by emulsifier‐free emulsion polymerization. The dependence of various parameters such as an electrolyte (NaCl), an initiator (K2S2O8), the phase volume ratio, the reaction temperature and time on the diameter and the particle size distribution has been discuss

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020207

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractCopolymerization of methacrylic acid alkali metal salts (MAAM; M = Li, Na, K, Rb or Cs) and oligo(oxyethylene) methacrylate (MEO) was carried out in bulk or in poly(oligo(oxyethylene) methacrylate) (PMEO) at 60°C. The copolymers of MAAM and MEO which were obtained by bulk polymerization showed a cation conductivity of around 1 × 10−7S/cm at room temperature. On the other hand, the copolymers obtained by radical polymerization in PMEO, showed a higher cation conductivity (10−6–10−5S/cm). Furthermore, higher cation conductivity was observed for the copolymer systems containing alkali metal cations with a larger ion radius. This tendency was explained by the strength of the bond between alkali metal cation and ether oxygens. The degree of dissociation had little effect on this difference in the conductivity. The effective dissociation of methacrylic salts was enhanced in the copolymer compared to the homopolymer because of the suppression of the adjacent dissociative carboxylic acid groups. Arrhenius plots for ionic conductivity show the migration of ions along with the segmental motion of the polym

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020208

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPolyethylene oxide (PEO) oligomers can dissolve lanthanide salts. The terminal hydroxyl groups of PEO affect the solubility of the lanthanide salts in the PEO considerably. However, no intensive fluorescence was observed from Eu3+dispersed in PEO or other ion‐conductive polymers containing terminal hydroxyl groups, because of the quenching effect of the terminal hydroxyl groups. Copolymer of ω‐methoxy oligo(oxyethylene) methacrylate and methyl methacrylate (P(MEOM‐co‐MMA)) could dissolve small amount of Eu(NO3)3, but the copolymer film containing Eu3+shows intensive fluorescence (Ex = 269.0 nm, Em = 570.0 nm). This was prepared as a soft film, and there was a clear dependence of the Eu3+concentration on the fluorescence intensity. A linear relation between the film thickness and the fluorescence intensity was also observed. Little fluorescence was found for Eu3+in the blend of the corresponding two homopolymers, i.e. poly‐(ω‐methoxy oligo (oxyethylene) methacrylate) (PMEOM) and poly(α‐methyl methacrylate) (PMMA). This strongly suggests that intensive fluorescence requires a mixed state of MEOM and MMA units at

ISSN:1042-7147    

DOI:10.1002/pat.1991.220020209

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY