摘要:

AbstractDifferent poly(vinyltoluene‐co‐divinylbenzene) networks, precursors for ionic polymers, were synthesized and characterized. The influence of diluent nature and divinylbenzene (DVB) content on copolymer properties is discussed. Both expanded and porous structures can be easily prepared. Expanded structures are formed when good or poor diluents are used for low DVB content, i. e. less than 20 wt.‐% with respect to vinyltoluene. Higher DVB content yields macroporous structures. Also, the possibility of obtaining strong base anion exchangers from poly(vinyltoluene‐co‐divinylbenzene) networks as precursors was investigated. Therefore, the above‐mentioned networks were transformed by the chlorination reaction with NaOCI/phase transfer catalyst system, followed by the amination reaction with trimethylamine or N,N‐dimethyl‐2‐

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220101

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of three organophosphonic compounds on the thermooxidative degradation of the uncured diglycidyl ether‐bisphenol‐A epoxy resin was investigated, using infrared spectroscopy, thermogravimetry, differential thermogravimetry, static pyrolysis, pyrolysis‐gas chromatography and elemental analysis. The results obtained indicate that additives with phosphorus and chlorine or nitrogen in molecules exercise an influence upon the degradative process of uncured resin by catalysing its decomposition in the lower temperature region. At the same time, the tested additives promote the formation of highly thermostable and non‐flammable structures in the solid

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220102

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractBagasse dissolving pulp was grafted with acrylonitrile by using a KMnO4oxalic acid redox initiator system. The effects of monomer concentration, reaction time, initiator concentration, acid concentration and reaction temperature were investigated.

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220103

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractIt is evident from Monsanto rheometric studies, dynamic mechanical analysis (DMA), physical property measurements and scanning electron microscopy (SEM) that the mixer rotor speed has an effect on the crosslinking of poly(acrylic acid) (PAA)/epoxidized natural rubber (ENR) blends. These studies reveal that mixing at high rotor speed deteriorates the crosslinking process between PAA and ENR. Infrared (IR) spectroscopic studies suggest that during mixing at high rotor speed ENR elastomer chains suffer breakdown through mechanochemical reactions.

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220104

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractActivity of carbon black toward natural, butyl, butadiene, butadiene‐styrene and butadiene‐acrylonitrile rubber has been evaluated. Peroxide, sulfur donor, sulfur/accelerator systems and also tris(2‐methyl‐1‐aziridinyl)phoshine oxide as crosslinking substances were used. Different activity parameters were taken into consideration. From the results it follows that activity of carbon black depends not only on its properties but also on the type of the elastomer matrix. An effect of chain flexibility, unsaturation degree, crosslinking density and chemical structure of the network has been

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220105

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractMelamine‐formaldehyde moulding compounds (MF) were modified by mechanical mixing with ethylene/vinyl acetate copolymers (EVA) and with partially hydrolysed EVA. Ether linkages between the hydrolysed material and the MF resin improve the mechanical properties of the transfer moulded parts containing the hydrolysed material compared to those made with EVA. The use of both modifying polymers improves the ductility and, in case of the partially hydrolysed material, the postshrinkage of the extremely rigid MF matrix, as long as the modification polymer content is kept low. On the contrary, Young's modulus and the heat deflection temperature are deteriorated. The improvement in impact strength by use of those uncrosslinked polymers is still insufficien

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220106

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractA large number of styrene‐divinylbenzene copolymers (St‐DVB) were synthesized using 2,2,4‐trimethylpentane as pore‐forming agent. Diluent and crosslinking agent (DVB) contents were varied in the ranges 20–60 vol.‐% and 2–40 vol.‐%, respectively, to generate various St‐DVB networks. Network features as apparent and skeletal densities, pore volume, mean pore diameter, specific surface area and pore size distributions were measured by mercury porosimetry. A compressing process occurring at the beginning of each measurement has been revealed and measured. Depending on the two synthesis parameters, the changes in pore diameter distributions are discussed. Those results, combined with the calculated average pore diameter and microscopy observations, allow to conclude that the synthesized matrices have a microspheres‐based structure with a network‐overlapping process occurring over 50 vol‐% of dilution. A macroporosity domain has been defined for networks having specific surface area

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220107

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractNew aromatic polyamide‐imides (PAI) containing various alkyl substituents were prepared by the substitution reaction of Torlon®4203L (commercialized PAI resin) with the corresponding alkyl halides such as methyl iodide, ethyl iodide, and n‐butyl bromide. The resulting amorphous PAIs with glass transition temperatures ranging from 238 to 276°C had inherent viscosities in the range of 51 to 53 mL/g. These polymers were readily soluble in aprotic polar solvents such as N‐methylpyrrolidone, dimethylformamide, dimethyl acetamide, etc. Furthermore, the incorporation of various alkyl substituents into amide groups of the PAI resin increased the melt processability, but slightly decreased the thermal properties compared with conventional PAI resin. The melt viscosities of resulting PAIs determined at 330°C under the frequency of 10‐1rad/sec were in the range of 103–105Pa.s. On the other hand, the modified PAIs showed significantly lower melt viscosities than Torlon®4203L, which was almost comparable to the conventional polyetherimid

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220108

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractA series of copolyesteramides based on adipic acid/1,6‐hexane diamine/ϵ‐caprolactone and Nylon 6,6 salt/ϵ‐caprolactone were synthesized. Their molecular weights, determined by gel permeation chromatography and NMR spectroscopy, were found to lie within the range from 1000 up to 7000. Their thermal properties (glass transitions, melting points and heats of melting, and decomposition temperatures) were recorded with diferential scanning calorimetry and thermogravimetry, respectively, and correlated to the comonomer feed composition. The FT‐IR and NMR spectra were also recorded in order to confirm the composition of the copolyesteramides and to compare them with that of the comonomer feed. The biodegradability of the synthesized copolymers was tested by enzymatic h

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220109

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe oil‐in‐water‐type (o/w) microemulsion polymerizations of butyl acrylate initiated by a water‐ (ammonium peroxodisulfate, AP)—and oil‐soluble (dibenzoyl peroxide, DBP, and 2,2′‐azoisobutyronitrile, AIBN) radical initiators were investigated. Polymerizations with AP were faster than those with DBP or AIBN. The rate of polymerization shows initiation and termination intervals, but no constant interval. The rate of polymerization is found to be proportional to the 0.46th, 0.53rd and 0.24th power of the AP, AIBN and DBP concentration. The rate per particle is found to be proportional to the 0.29th, 0.32nd and 0.37th power of the AP, AIBN and DBP concentration. The number of radicals per particle was found to increase with increasing the initiator concentration. The most pronounced increase in the number of particles with increasing the initiator concentration was observed with AP, much less with AIBN and the slight decrease with DBP. The molecular weights of polymers were found to vary only slightly with increasing the initiator concentration. The formation of radicals proceeds in the aqueous phase (AP and a water‐soluble fraction of AIBN or DBP) and the monomer‐swollen micelles (AIBN or DBP) as well. The polymer particles grow by recruiting monomer and emulsifier from the free monomer‐swolle

ISSN:0003-3146    

DOI:10.1002/apmc.1994.052220110

出版商:Hüthig&Wepf Verlag    

年代:1994

数据来源: WILEY