摘要:

AbstractKinetic studies were carried out on the reaction between ethylenediamine and dimeric fatty acids in melt phase. The reaction was performed at 124, 130, 145, 160, 174, and 190°C and followed by determining the acid value of the product. The polyamidation reaction was found to be of overall second order with an activation energy of 18.2 kcal/g mol up to 90% conversion and of overall third order with an activation energy of 16.4 kcal/g mol above 90% conversion

ISSN:0021-8995    

DOI:10.1002/app.1988.070360701

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA theoretical and experimental study was carried out to investigate the process of electrodepositing a polyamic acid film from a nonaqueous emulsion onto a metal surface (copper, aluminum) as well as the subsequent drying and imidization steps. The rate of film growth is controlled by the electrophoresis of the polymer emulsion particles to one of the electrodes and the concomitant film compaction due to the outflow of the solvent caused by electro‐osmosis. Parameters affecting the coating process such as particle size, charge, ζ potential, viscosity of the liquid medium, conductivity of the deposited film, etc. were consider

ISSN:0021-8995    

DOI:10.1002/app.1988.070360702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe equilibrium water content (EWC) of thermoplastic 2‐hydroxypropyl methacrylate and 2‐hydroxyethyl methacrylate homopolymers from technical grade monomer and of copolymers of the latter with methyl methacrylate has been measured in distilled water and in phosphate‐buffered saline (PBS). In distilled water, as expected, EWCs increased monotonically with the proportion of hydrophilic monomer in the polymer and showed only a small dependence on molecular weight. In contrast, the degree of swelling (and in some cases dissolution) and “freezable” water content of polymers in PBS were shown to be anomalously high and to be a consequence of ionization at pH 7.4 of methacrylic acid incorporated into the polymer in small quantity (<1 mol %) as an impurity. Initial studies indicated a strong relationship between copolymer molecular weight and small molecule permeability in distil

ISSN:0021-8995    

DOI:10.1002/app.1988.070360703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCurrent interest for implantable insulating biomaterials has resurrected a class of polymers synthesized fromp‐xylylene and its derivative dimers. Important kinetic aspects for the synthesis of the polymer are derived from measurements of chamber pressure and total weight of film deposition. Reduction of peak chamber pressure during polymer deposition was found to improve film quality, uniformity of deposit, adhesion, and transparency. A low‐cost reactor design is proposed which simplifies the deposition characterization steps needed for producing high quality fi

ISSN:0021-8995    

DOI:10.1002/app.1988.070360704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractFar infrared (FIR) birefringence is a new tool for measuring orientation in semicrystalline polymers. In this work FIR birefringence of high‐pressure injection‐molded high‐density polyethylene (HDPE) was compared with wide‐angle X‐ray scattering (WAXS) and shrinkage for the first time. An indirect measure of orientation was obtained by differential thermal analysis (DTA). The content of high‐temperature melting crystals was found to increase with increasing orientation. A high correlation was found between FIR birefringence and the other orientational measurements. Contrary to the other orientational methods used, FIR birefringence does not saturate with highly oriented samples. It is furthermore faster, nondestructive, and can be used for probing fairly th

ISSN:0021-8995    

DOI:10.1002/app.1988.070360705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0021-8995    

DOI:10.1002/app.1988.070360706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractStructural features of bhindi fiber have been studied by X‐ray diffractometry, scanning electron microscopy, and infrared spectroscopy. The fiber has multicellular structure and on alkali treatment, it behaves like other lignocellulosic fibers. Infrared spectra indicated that alkali degradation of cellulose and hemicellulose was quite significant in the fiber and that substantial portion of uronic acid was removed as a results of alkali treatmen

ISSN:0021-8995    

DOI:10.1002/app.1988.070360707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of fillers such as glass, ferrite, and carbon on the dielectric properties of epoxide resin along with conductivity has been studied as a function of frequency (1–100 kHz) and temperature (30–200°C). The glass transition temperature is not much affected by the presence of the fillers. The observed higher values of dielectric permittivity and loss in the case of filled polymers are attributed to Maxwell–Wagner–Sillars pola

ISSN:0021-8995    

DOI:10.1002/app.1988.070360708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMacroporous chelating resins (RNH‐DVB‐1G) containing amidoxime groups with various degrees of crosslinking were synthesized by varying the amount of divinylbenzene (DVB) and ethyleneglycol dimethacrylate (1G). It was confirmed that the content of amidoxime group decreased with an increase in the degree of crosslinking. On the other hand, the amount of amidoxime group hydrolyzed by acid treatment showed a tendency to decrease with an increase in degree of crosslinking. From the measurement of specific surface area and pore size distribution, it was found that the macropore of RNH‐DVB‐1G with the same degree of crosslinking was remarkably affected by the composition of crosslinking reagent (DVB and 1G). The RNH‐DVB‐1G prepared in the present work were applied to the recovery of uranium from seawater. It was found that the uranium adsorption ability of RNH‐DVB‐1G with the same degree of crosslinking was remarkably affected by the proportion of DVB and 1G, although each RNH‐DVB‐1G had the same content of amidoxime group. In the case of RNH‐DVB‐1G prepared with 25 mol% of crosslinking reagent, the resin prepared with 10 mol% of DVB and 15 mol% of 1G showed the high adsorption ability for uranium in seawater. These results indicate that the simultaneous use of DVB and 1G contributes to the formation of effective macropore and micropore for recovery of uranium from seawater and the increase of chemical

ISSN:0021-8995    

DOI:10.1002/app.1988.070360709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of solvent treatment on the dyeability and mechanical properties of drawn poly(ethylene terephthalate) (PET) filaments has been studied. It is observed that strongly interacting solvents such asN,N‐dimethyl formamide (DMF) improved the dyeability of PET which has been treated with these solvents at 74°C for 15 min before dyeing with disperse dyes at 100°C. Pretreatment inN,N‐dimethyl formamide and acetonitrile also resulted in a lowering of tensile strength and initial modulus, whereas subsequent dyeing caused further reduction in extensibility but initial modulus results are less consi

ISSN:0021-8995    

DOI:10.1002/app.1988.070360710

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY