摘要:

AbstractThe thermal stability of sodium alginate (SA) and its graft copolymers of acrylonitrile (AN), methyl acrylate (MA), ethyl acrylate (EA) and methyl methacrylate (MMA) has been examined in air atmosphere by means of thermogravimetric analysis. The following order of decreasing stability was found from characteristic decomposition temperatures: SA‐g‐PAN>SA‐g‐PMA>SA‐g‐PEA>SA‐g‐PMMA. The overall thermal stability of the different SA graft copolymers was evaluated by comparing their activation energies of thermal degradation; it agreed with the same order of th

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350101

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA poly(vinyl alcohol)‐β‐cyclodextrin (PVA‐BCD) copolymer was prepared by successive reaction of BCD with toluylene diisocyanate and PVA. Copolymer formation was evidenced by infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. Scanning electron micrographs show morphological differences between PVA and the copolymer. The copolymer, being almost insoluble in common solvents with an equilibrium swelling in water of 50%, is a potential membrane ma

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350102

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractElectrorheological (ER) fluids composed of a dispersing medium with a low dielectric constant and polyaniline particles, deprotonated with ammonia or sodium hydroxide at different concentrations for 24 h were studied. The effects of dielectric constant, conductivity and volume fraction of the polyaniline particles, the kind of dispersing medium, addition of surfactant, as well as the electric field strength and temperature on the ER properties of the ER fluids were investigated. The results showed that a moisture‐insensitive, highly ER‐active fluid can be obtained from chlorinated paraffin oil and polyaniline particles deprotonated with ammonia water at certain pH values and exhibited a static yield stress>10 kPa and current density<40 μA cm−2at 2.8 kV mm−1DC electr

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350103

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA phenolic resin/polyurethane copolymer was synthesized by reaction of a phenolic resin, a blocked‐polyurethane and p‐toluene sulfonic acid. The copolymer provides a good balance between the processability (including pot life, reactivity) and toughness. The reactions that proceeded during the synthesis of the copolymer was investigated by IR spectroscopy. It was found that blocked polyurethane reacted with the hydroxy group of the phenolic resin. Glass fiber‐reinforced composites showed excellent bonding between fiber and matrix as revealed by SEM photographs. An overlap peak was found from the DMA diagram; it indicated that an interaction existed between phenolic resin and polyurethane and that improved the toughness of the phenolic

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350104

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe plastic zone size and crack opening displacement of phenolphthalein polyether ketone (PEK‐C) at various conditions were investigated. Both of them increase with increasing temperature (decreasing strain rate), i.e. yield stress steadily falls. Thus, the mechanism increasing the yield stress leads to increased constraint in the crack tip and a corresponding reduction in the crack opening displacement and the plastic deformation zone. The effect of the plastic deformation on the fracture toughness is also discusse

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350105

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDie Wasserabsorptionseigenschaften natürlicher Makromoleküle, die als kationische Aminogruppen das Polysaccharid Chitosan oder das Polypeptid Polylysin und als anionische Carboxygruppen das Polysaccharid Carboxymethylcellulose oder das Polypeptid Polyglutaminsäure (PGA) enthalten, wurden untersucht. Bei Kombinationen von Polysacchariden oder Polyaminosäuren untereinander zeigten Gemische mit einem Ionenverhältnis von 1 : 1 die geringste durch Wasser hervorgerufene Quellung. Demgegenüber fand sich im Falle von Chitosan/PGA‐Gemischen bei Zusammensetzungen mit PGA‐Überschuß ein Minimalwert, während die Polyaminosäuren eine strukturell verhältnismäßig freie räumliche Anordnung einnahmen.Durch Vergleiche der durch DSC‐Analyse bestimmten Enthalpien wurde bestätigt, daß die Komplexe mit Pyranose‐Ringstrukturen enthaltenden Filmkomponenten größere Mengen Wasser in Form von nicht ausfrierbarem Wasser halten können. Ferner ergab ein Vergleich der mechanischen Festkörpereigenschaften, daß sich bei Zusammensetzungen der Komplexe mit großen Mengen an Polysacchariden eine Tendenz zu einem erh

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350106

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractGrafting of acrylic acid onto pre‐irradiated poly(tetrafluoroethylene‐hexafluoropropylene) (Teflon‐FEP) films was investigated, and the reaction parameters dose, dose rate, monomer concentration and grafting temperature were examined.The results show that the degree of grafting depends on the dose (5‐60 kGy), the weight of grafted specimen increased up to 37%. The degree of grafting was found to be independent of the dose rate.The overall activation energies were calculated to be 28.8 and 81.6 kJ mol‐1for treatments at above and below 50°C, respectively.The swelling of grafted films was measured in water, aqueous potassium hydroxide and methanol. The degree of swelling was found to increase with the length of graf

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350107

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA systematic study of filled natural rubber (NR) vulcanizates has been carried out to investigate the effect of a crosslinkable processing aid, trans‐polyoctenylene (TOR) on stress‐strain properties at high temperature and after ageing. Three different crosslinking systems, i. e., conventional (CV), semi‐efficient (SEV) and efficient (EV), are included in this study. Retention of 200% modulus and tensile strength (TS) at high temperature as well as after ageing has been found to be better with TOR in the CV system. TGA results of gum polymeric blends showed enhanced stability with addition of TOR in both oxygen and nitrogen atmosphere. Enhanced thermal stability is also exhibited by higher onset and peak temperature while determining the rescan enthalpy of the filled vulcanized sample by means of DSC. FTIR (ATR) spectra however show no polymeric interaction between NR and TOR. The improvement of properties in the CV system has been explained with the help of DSC results and a probable mechanism has been suggested on the changes of network stru

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350108

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractIt was attempted to improve the fiber/rubber adhesion by surface modification of fibers by excimer laser irradiation. The fibers were first treated with a glycidyl ether acrylate compound which is sensitive to UV rays, then cured with a KrF laser and treated with an ordinary RFL (resorcinol formalin rubber latex), and then cured in heat. For poly(ethylene terephthalate) (PET) and poly(p‐phenylene‐3,4′‐oxydiphenylene terephthalamide) (PPODPTA) fibers, the adhesion performances were improved, whereas for poly(p‐phenylene terephthalamide) (PPTA) fibers they were not. In PET fibers, the surface layer was converted into the amorphous state, and therefore the affinities for the treating agents were enhanced. As for the aramid fibers, the copolymer components of the PPODPTA fibers contain crystalline domains, independently, which are oriented sufficiently, leaving almost no amorphous state in which molecules remain relaxed, and are difficult to be fibrillated. On the other hand, the PPTA fibers comprise a skin layer and a core layer composed of fibrils stacked into blocks. Between the blocks, amorphous phases containing a relatively large number of molecular chain ends are present, facilitating the fibrillation. Probably, the molecules in the non‐crystalline state of both of the fibers were relaxed differently, causing different susceptibilities to ablation. This might result in different affinities to the acrylate compound, or different adhesion performances, r

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350109

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA series of new poly(1,3,4‐oxadiazole‐imide)s has been synthesized from various aromatic dihydrazides and diacid chlorides which contain both imide and hexafluoroisopropylene units. The diacid chlorides were reacted with aromatic dihydrazides to prepare poly(hydrazide‐imide)s which were subsequently cyclodehydrated in their solid state to give poly(1,3,4‐oxadiazole‐imide)s. The new polymers were soluble in polar solvents and were stable up to 450‐480°C in nitrogen, as determined by thermogravimet

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052350110

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY