摘要:

AbstractA series of sulfonated cationic resins have been prepared and characterized from Egyptian bagasse pith wastes (as a source of cheaper and renewable material) with m‐cresol and paraformaldehyde as a crosslinking agent. Reaction conditions for the preparation are presented and properties of the synthesized sulfonated bagasse pith‐m‐cresol‐formaldehyde resins are described and compared with resin not containing bagasse pith. The synthesized resins are stable in water, dilute mineral acids (1 M), organic solvents, and to thermal treatment. The resins having a cation exchange capacity up to 2.91 meq g‐1of dry resin, are being introduced as new exchangers. The synthesized resins are used in the study of the possible separation of some bivalen

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180101

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of styrene content on the properties of electron irradiation‐vulcanized SBR loaded with carbon black was pronounced only at low irradiation doses where the crosslinking densities were not so high. At high doses, no effect was observed especially for SBR containing ZnO. It was also observed that ZnO (3 phr) increased the tensile strength of SBR containing 23.5 wt.‐% styrene by 20% at 20 kGy irradiation dose, compared to 5% at higher doses for SBR containing 46 wt.‐% styrene. However, the increase in tensile strength by ZnO for loaded SBR (23.5%) was almost 17% at all irradiation doses. Besides, tear strength, abrasion resistance and elongation at break were remarkably improved. The high efficiency of ZnO toward SBR (23.5%) may be attributed to the higher butadiene content. The behavior of SBR (46%) at 20 kGy was surprising, since both tensile strength and elongation at break were almost ma

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180102

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractAttempts have been made to provide hydrophilic sites onto the surface of ethylene‐propylene rubber (EPR) by grafting 2‐hydroxyethyl methacrylate (HEMA) and N‐vinylpyrrolidone (NVP) onto the surface of this elastomer using CO2‐pulsed laser as excitation source. The effect of benzophenone (BZP) and azoisobutyronitrile (AIBN) as photosensitizer upon the graft level has been evaluated. CO2‐pulsed laser grafting of HEMA and NVP was found to be dependent upon the wavelength, repetition rate, and fluence of laser. Hydrophilicity of EPR increased upon grafting HEMA and NVP with CO2‐pulsed laser. Surface characterization has been carried out using attenuated total reflectance infrared spectroscopy (ATR‐IR), scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDXA). IR‐laser grafting of these monomers is not possible unless the system is irradiated by pulses with the wavelength corresponding to the either maximum absorption of monomer or sensitizer accessible to the laser equipment gain. As the absorption of EPR at these wavelengths is quite low, it is believed that depending upon the wavelength, either photosensitizer and/or monomer molecules are excited through an infrared multiphoton excitation (IRMPE) process above the dissociation energy leading to the decomposition of the excited molecules. Addition of a multifunctional acrylate (MFA) such as 1,1,1‐trimethylolpropane‐trimethacrylate (TMPTA) to the grafting system enhanced the graft yield. Poly(HEMA) grafted onto the surface of EPR by CO2pulsed laser tends to form a fractal type of morphology. The shape and size of fractals depends upon both laser parameters and HEMA concentration. EDXA analysis showed the presence of ungrafted (hydrophobic areas) as well as hydrophilic sites (fractals) on the surface of modified samples. Finally, the bulk mechanical properties of EPR after being laser‐grafted with HEMA or NVP did not c

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180103

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractA feasibility study of pultrusion of fiber‐reinforced polyurethane/furfuryl alcohol (PU/FA) interpenetrating polymer/network IPN composites has been made. From the viscosity study, it was found that the pot life of the PU/FA IPN prepolymers increased with PU content and showed high reactivity at elevated temperature. It was confirmed from the morphological study that the wetting of fibers by the PU/FA IPN resins was improved with PU content. The appearance of the tensile failure surfaces of the pultruded glass fiber‐reinforced PU/FA IPN composites showed “hackle patterns” for PU contents below 15 phr. The mechanical property study shows that the tensile strength of pultruded PU/FA IPN composites is the highest when the PU content is 5 phr. However, the flexural strength, flexural modulus and HDT decreased with PU content. The mechanical properties of various fiber‐reinforced (glass, carbon, and Kevlar 49 aramid fiber) pultruded PU/FA IPN composites increased with fiber volum

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180104

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe emulsion polymerizations of butyl acrylate initiated by water‐soluble (ammonium peroxodisulfate, AP) and oil‐soluble (dibenzoyl peroxide, DBP) radical initiators were investigated. Polymerizations were found to be faster with AP. The size of polymer particles formed and the molecular weights decreased with increasing temperature and increased with conversion. The number of particles was constant in the conversion range from ca. 30 to 100%. The overall activation energy (E0) was found to be ca. 50–60 kJ · mol‐1which is nearly half of that of the bulk polymerization. The activation energy of the AP‐initiated polymerization was found to be independent of conversion while that for the DBP‐initiated polymerization decreased with conversion, and the decrease was more pronounced beyond 60% conversion. This behavior was discussed in terms of the emulsion and bulk polymerizations and variations of the activation energy for termination with viscosity of the re

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180105

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractDie Beeinflussung von Merkmalen der Polymerstruktur durch Behandlung mit überkritischem CO2wird anhand von Polyesterfasermaterial untersucht. Das überkritische System verursacht eine Absenkung der Glastemperatur und bewirkt die Ausbildung netzwerkstabilisierender Kristallite in den fehlgeordneten Bereichen des Fasermaterials, die denen entsprechen, die ohne Gegenwart eines überkritischen Fluids erst bei deutlich höheren Behandlungstemperaturen gebildet werden. Die Bedeutung der Polymerstruktur für Fäbung bzw. Imprägnierung von Fasermaterial in überkritischen Systemen wird dis

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180106

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractCe travail sur le rôe des pigments définit le comportement d'un nouveau systeme photosensible qui permet de polymériser des milieux épais et pigmentés selon un procédé en une seule étape. Les différentes interactions présentes en milieu pigmenté sont décrites de façon qualitative, et la part de l'intensité lumineuse absorbée par un photo‐amorceur dans un systéme pigmenté est evaluée. Les propriétés optiques telles que l'absorption et la réflectance des différentes familles chimiques de pigments sont déterminées, et, en paralléle, les propriétés optiques des différentes sources d'irradiation sont étudiées de manière à répondre au mieux aux fenêtres de transmission des pigments. L'effet photocatalytique de certains pigments est mentionné, ceci afin d'amk

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180107

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractCondensation of 3‐glycidyloxypropyltrimethoxysilaneIwith diphenylsilanediolIIwas investigated. Depending on solvent, temperature and catalyst, different products were obtained. Bulk reaction at 120°C using titanium(IV)‐isopropylate as a catalyst provided the transparent resinA. Awas characterised by IR,1H‐ and13C‐NMR spectroscopy and contained no reactants. GPC and HPLC studies revealed thatAconsists of trimer and tetramer siloxanes of pertinent diphenylsilane and 3‐glycidyloxypropylmethoxysilane moieties. The proportion of cyclic to linear molecules was evaluated 2:1. Only small amounts of high‐molecular‐weight compounds were observed. The epoxysiloxane product proved to be miscible with various organic solvents and with commercial epoxy resins. Time dependence of viscosity and epoxy content were recorded during ambient storage and monitored by HPLC. Pot‐life was improved by a subsequent t

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180108

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper presents the results of studies on the synthesis and curing of millable polyurethanes based on castor oil. To facilitate the preparation of millable urethanes, the hydroxy number of castor oil was modified to about two by acetylation. It was then used with tolylene diisocyanate (NCO/OH‐ratios 1:0.9, 1:1 and 1:1.1, resp.) for polyurethane preparation. The dynamic curing of the synthesized polyurethanes was studied in a Brabender Plasticorder using various sulfur vulcanizing systems. The effect of stoichiometric ratio and choice of chain extenders on the dynamic curing behaviour was also studied. An NCO/OH ratio of 0.9 and 1,4‐butanediol (30 wt.‐%) as chain extender were found to favour the formation of a crosslinkable polyurethane. It was observed that a cure system containing sulfur, N‐cyclohexyl‐2‐benzothiazole sulfenamide and mecraptobenzothiazole was a possible choice for the preparation of a sulfur‐crosslinked

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180109

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis of polypyrrole from aqueous solutions using various organic anion electrolytes and its electric and mechanical properties and the junction characteristics of sandwich devices were investigated.As electrolytes the following anions were used: p‐toluenesulfonate (p‐TS‐), benzenesulfonate (BS‐), dodecylbenzenesulfonate (DBS‐), naphthalene‐2‐sulfonate (N‐2‐S‐) and sulfosuccinate (SS‐1); their effect on the conductivities of the polypyrroles decreases in the order DBS‐1>p‐TS‐1>N‐2‐S‐1>BS‐>SS‐. Higher conductivity and mechanical properties were obtained by drawing of films. With indium, polypyrrole forms rectification contacts, whereas ohmic contacts are formed in junction with Au or Pt. From the analysis of the current‐vs.‐voltage and capacitance‐vs.‐voltage characteristics, it is suggested that a Schottky barrier is formed at

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052180110

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY