摘要:

AbstractTetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM) undergoes homopolymerization on heating. Intramolecular reactions which compete with crosslinking favor the formation of cyclic structures with increasing thermal and fire resistance of the resin, whereas physical mechanical properties tend to decrease.The mechanism of thermal decomposition of TGDDM is studied by thermogravimetry, differential scanning calorimetry and thermal volatilization analysis with characterization of volatiles evolved and residue left. Thermal degradation of poly‐(TGDDM) starts at 260°C with elimination of water from secondary alcoholic groups which is a typical pathway for epoxy resin degradation. Resulting unsaturations weaken bonds in the β‐position and provoke the first chain breaking at allyl–amine and allyl–either bonds. With increasing temperature, saturated alkyl–ether bonds and alkyl carbon–carbon bonds are broken first, followed by the most stable alkyl–aryl bonds at T>365°C. The combustion performance of TGDDM is discussed on the basis of the thermal

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060201

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPoly(ethylene terephthalate) and a series of other amorphous copolyesters based on ethylene glycol and terephthalic/isophthalic or 2,6‐naphthalenedicarboxylic/isophthalic acid mixtures were prepared by melt polycondensation. Comonomers consisting of azoic dyes having two polymerizable functions on the aromatic rings (either one alcoholic and one carbomethoxyl, two alcoholic or two carbomethoxyl groups) were also added, in amounts lower than 1% mol with respect to the sum of diesters used as starting monomers. In these conditions (P<0.1 torr and T=280°C), only few azoic dyes were found to be stable.Among the prepared polymers, those based on dyes having sufficient thermal stability were characterized by differential scanning calorimetry and solution properties. Inherent viscosities suggest that molecular weights are high. Glass transition and melting temperatures as well as mechanical properties of colored polyesters are not affected by the presence of the azoic comonomers. UV–visible spectra of copolyester solutions were registered, and absorption coefficients were correlated with the amount of

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060202

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA novel wet water–ethanol‐borne technique of preparing nanocrystals of the poly[5,7‐dodecadiyn‐1,12‐diol bis‐(n‐butoxycarbonylmethyl urethane)], oxoreferred to as poly(4‐BCMU), is reported for the first time. The fabrication of poly(4‐BCMU) nanocrystals with sizes ranging from a few to hundreds of namometers is presented. The spectroscopic analysis of the poly(4‐BCMU) nanocrystals using nuclear magnetic resonance, infrared, optical absorption spectroscopy, gel permeation chromatography and scanning electron microscopic techniques is discussed. A structural characterization at molecular level of the poly(4‐BCMU) constituting the nanocrystals evidences the maintenance of the molecular integrity of the pol

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060203

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA review of work which has been performed on high temperature polymer blends is presented. The discussion is divided into miscible and immiscible blends. It is pointed out that one problem with miscible polymer blends is that of processing in the miscible state. In the case of immiscible blends, particularly ones containing liquid crystal polymers, the issue of adhesion of the two phases is discussed. Finally, the need for better theoretical models for predicting miscibility in polymer blends is highlighted.

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060204

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractSolid polymer electrolytes (SPE) have been identified as a class of materials which could enable the fabrication of high energy density solid state lithium rechargeable batteries which could meet the performance requirements for advanced portable electronic and automotive applications. In order to achieve this goal, novel SPE systems having high ionic conductivity and good mechanical properties at or near ambient temperature must be developed. Novel lithium salts believed to be useful in realizing this objective have recently been proposed. The thermal behavior of SPE systems based on high molecular weight poly(ethylene oxide) (PEO) and on two novel salts, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the lithium tris(trifluoromethylsulfonyl)‐methanide (LiTSFM) is reported and compared with the thermal behavior of the high molecular weight PEO–lithium trifluoromethane sulfonate (LiTFLT) SPE system. Phase diagrams for the PEO–LiTFSI and PEO–LiTFSM SPE systems have been established and are discussed in terms of their impact on SPE‐based rechargeable lithium battery technologies. The use of a novel plasticizer in conjunction with the PEO–LiTFSI‐based SPE system is reported and it is shown how this modifies the thermal behavior of the PEO–Li

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060205

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPolycarbonate‐triad‐4–co‐polybutylene terephthalate liquid crystalline blends were prepared and spun into fibers. It has been shown that fibrillation of the thermotropic liquid crystalline polymer (TLCP) takes place at the given spinning conditions, forming thus “in situ” reinforcement. Continuous fibrils are formed at concentrations between 2.5 and 5% LCP. A degree of miscibility between two phases was observed. The moduli of both as‐spun and cold drawn fibers increase almost linearly with increasing concentration of TLCP. Tensile strength was found to decrease and elongation at break to increase with increasing TLCP content. The structure of the cold drawn fibers was not stable with time, causing a relaxation in the observ

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060206

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of poly(ethylene glycol) (PEG) 4000 on the corrosion of zinc‐plated steel in H2SO4has been investigated over a wide range of conditions. It was found that the corrosion rate depends upon exposure time. The rate of corrosion goes down rapidly to reach a low value, which is an almost constant value within 5 hr under most conditions. This trend was also found by Growock and Lopp for the inhibition of steel corrosion in HCl with 3‐phenyl‐2‐propyl‐1‐ol. Other workers have linked this slow fall‐off in the corrosion rate to film formation. The corrosion rate was found to decrease slowly with increasing PEG concentration, and to increase slowly with acid concentration for all conditions.The effect of temperature on corrosion rate was found to be similar to that of acid concentration. The corrosion rate decreased exponentially with poly(ethylene glycol) concentration. The percentage inhibition reached a value of 48.93 for a PEG concentration of 4 ppm: to double this, the concentration had to be increased to 40,000 ppm.Sulphuric acid titration against sodium hydroxide showed no change in acid concentration during the corrosion protection process, thus supporting the film pro

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060207

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY