bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese und charakterisierung von butadien‐divinylbenzol‐copolymeren
Authors: Burghardt Kathrin , Häusler Karl‐Georg , Martl Michael Gerd , Hummel Klaus , Gebauer Ulrich , Gehrke Klaus 
Published: April 2003

AbstractIm Rahmen von Arbeiten zur Modifizierung des cis‐1,6Polybutadiens wurde die Copolymerisation von Butadien und einer Divinylbenzolfraktion, insbesondere der Bereich mit kleinen Divinylbenzolgehalten, untersucht. Neben dem Ziegler‐Natta‐Katalysator Nickeloctanoat/Bortrifluoridetherat/Aluminiumtriethyl kam auch ein Nickeloctanoat/Titantetrachlorid/Aluminiumtriethyl‐System zur Anwendung, welches es durch seine höhere Aktivität gegenüber Vinylaromaten ermöglicht, großere Mengen der Divinylbenzolfraktion zu polymerisieren. Durch die Anwendung von spektroskopischen, pyrolysegaschromatographischen und thermoanalytischen Charakterisierungsmethoden können Beziehungen zwischen den erhaltenen Glas‐, Kristallisations‐ und Schmelztemperaturen und der Mikrostruktur des Polymeren hergestellt werden. Es zeigt sich, daß sowohl das Divinylbenzol als auch die trans‐1,4 bzw. die 1,2‐Vinyl‐Einheiten statistisch in das Polymere eingebaut werden. Damit eignet sich neben der Pyrolysegaschromatographie besonders die Differential Scanning Calorimetry als eine einfache Methode zur Charakterisierung der Struktur von aus technischen Fraktionen erhaltenen und teilweise vernetzten Polymerproben.
Morphologiebildungs‐ und dispergiermechanismen bei der herstellung und verarbeitung von polymer‐blends aus acrylnitril‐butadien‐styrol‐(ABS)‐ bzw. Styrol‐acrylnitril‐(SAN)‐copolymerisaten mit thermoplastischem polyurethan (TPU)
Authors: Radusch Hans‐Joachim , Hendrich Rea , Michler Goerg H. , Naumann Irene 
Published: April 2003

AbstractAn ABS/TPU‐ bzw. SAN/TPU‐Blends wurden Untersuchungen zur Morphologiebildung beim Schmelzemischen auf der Basis der Analyse des viskoelastischen Verhaltens der Komponenten angestellt. Unter definierten Bedingungen im Laborkneter gemischte und unter definierten Bedingungen mittels Hochdruckkapillarviskosimeter extrudierte Blendproben wurden hinsichtlich ihrer Phasenmorphologie elektronenmikroskopisch charakterisiert. Die mittels der rheologischen Analyse prognostizierten Morphologietypen und Morphologiebildungsmechanismen konnten anhand der elektronenmikroskopischen Aufnahmen und der quantitativen Morphologieanalyse bestätigt werden. Es zeigte sich, daß das Viskositätsverhältnis der Komponenten primären Einfluß auf die Morphologiebildung ausübt. Darüber hinaus sind auch thermomechanisch induzierte molekulare Abbauvorgänge und thermodynamische Wechselwirkungen sowie damit im Zusammenhang stehende Kristallisationsbedingungen für die TPU‐Phase hinsichtlich der resultierenden Phasenmorphologie nicht zu vernachlässigen.
Photoinitiated surface grafting of synthetic fibers, I. Photoinitiated surface grafting of ultra high strength polyethylene fibers
Authors: Feng Zhenguo , Rånby Bengt 
Published: April 2003

AbstractPhotoinitiated surface grafting of acrylic monomers has been carried out onto high strength polyethylene (HSPE) yarn by means of a continuous process. The grafting reaction is initiated by UV irradiation of the yarn after presoaking in an acetone solution of initiator and monomer. Four initiators, benzophenone (BP), 4‐chlorobenzophenone (4‐CBP), 2‐hydroxy‐2‐cyclohexylacetophenone (HHA), and 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA), and two monomers, acrylic acid (AA) and acrylamide (AM), have been used. After short irradiation time (10 to 20 s) successful grafting is obtained, as shown by ESCA and IR‐ATR spectra, dye adsorpotion from aqueous solution, and measurements of adhesion of single filaments to epoxy resin. Grafting efficiency of 74% has been reached for AA as monomer (26% is homopolymer). The tensile strength and modulus of the HSPE yarn are retained in the grafting process. The degree of surface grafting is mainly a function of structure and concentration of monomer and photoinitiator in the presoaking solution and of the irradiation conditions used. Increasing irradiation time gives increasing amounts of grafted polymer up to a certain limiting value. The reactivities of the four initiators have been compared showing the highest grafting yields of AA with BP and of AM with 4‐CBP as photoinitiator. AA grafted HSPE yarn can be dyed to rather deep color by dipping in an aqueous solution of Crystal Violet. Increased dye absorption by a factor of up to seven has been measured for yarn grafted with AA to the maximum level obtained. The filaments of the grafted yarn show increased adhesion to epoxy resin by a factor of up to five compared with the ungrafted filaments.
Water‐soluble polyamides as potential drug carriers, V. Carboxy‐functionalized polyaspartamides and copolyaspartamides
Authors: Machado M. De L. , Neuse E. W. , Perlwitz A. G. 
Published: April 2003

AbstractPoly‐α,β‐D, L‐aspartamides featuring carboxy‐functionalized side groups are synthesized by three different preparative routes: (i) aminolytic ring opening in polysuccinimide, (ii) N‐carboxymethylation of amine‐functionalized polyaspartamides, and (iii) nucleophilic addition of iminodiacetic acid to acryloylamino‐substituted poly‐aspartamides. The polymeric products, possessing inherent viscosities in the wide range of 5–30 ml g−1, are characterized microanalytically and spectroscopically. By virtue of the carboxylic acid side groups lending themselves to the reversible covalent bonding of suitably structured drug models, the polymers are designed to function as macromolecular carriers of chemotherapeutically active agents. Being perfectly soluble in aqueous media over a wide pH range, they fulfill a crucial precondition for carrier components in (parenterally administered) polymer‐drug conjugates.
Untersuchungen von dünnen filmen auf basis von poly(p‐phenylen‐1,3,4‐oxadiazolen)
Authors: Schulz Eckhard , Leibnitz Eberhard , Bauer Albrecht , Schmolke Rudolf 
Published: April 2003

AbstractEs wird über die Herstellung und Charakterisierung von dünnen Filmen aus Poly(p‐phenylen‐1, 3,4‐oxadiazolen) berichtet. Die aus H2SO4‐Lösungen präparierten Filme besitzen eine gute optische Transparenz und sind mechanisch stabil. Filme aus Michungen mit Polyamiden zeigen ein ähnliches Verhalten und sind aufgrund ihrer thermischen Eigenschaften für spezielle Anwendungen interessant. Bei faserverstärkten Filmen zeigen erste Untersuchungen, daß spezielle Grenzflächenbereiche entstehen.
2,3‐dihalogen‐1,4,7‐heptantriole als flammschutzmittel in PUR‐hartschäumen
Authors: Marzec Krzysztof 
Published: April 2003

AbstractDie Verwendbarkeit der aus 2‐Furaldehyd erhaltenen Halogentriole 2,3‐Dichlor‐ und 2,3‐Dibrom‐1,4,7‐heptantriol als reaktive Flammschutzmittel für PUR‐Hartschäume wurde untersucht. Zur Modifikation der Schäume wurden diese Verbindungen allein und im synergistischen System mit Antimontrioxid verwendet.
Preparation of multiphase block copolymers by redox polymerization process
Authors: Hazer Baki , Cakmak Ismail , Denizligil Selcuk , Yagci Yusuf 
Published: April 2003

AbstractRedox polymerization of methylmethacrylate (MMA) using Ce(IV) with poly(oxyethylene) having azo and hydroxy functions was carried out to yield methylmethacrylate‐ethylene glycol block copolymers with labile azo linkages in the main chain. These prepolymers were used to initiate the radical polymerization of styrene through the thermal decomposition of the azo group, resulting in the formation of multiblock copolymers. Successful blocking has been confirmed by fractional precipitation, a strong change in the molecular weight distribution and spectral measurements.
Monodisperse polymer beads as packing material for high‐performance liquid chromatography. Synthesis and properties of monidisperse polystyrene and poly(methacrylate) latex seeds
Authors: S̆migol Vladmír , S̆vec Frantis̆ek , Hosoya Ken , Wang Qing , Fréchet Jean M. J. 
Published: April 2003

AbstractThe effects of initiator concentration, ionic strength of polymerization medium, polymerization temperature, and monomer/water phase ratio on particle size, particle size distribution and molecular weight of the resulting polymers prepared by an emulsifier‐free emulsion polymerization of styrene, methyl methacrylate and glycidyl methacrylate have been studied. Optimal conditions for preparation of uniformly sized polystyrene particles larger than 1 μm have been found. An attempt to synthesize monodisperse particles of similar size from methacrylate monomers and crosslinked particles has failed. It is shown that the swelling ability of “non‐activated” latex particles does not exceed 70 fold increase in the volume and strongly depends on the size of the original particles.
Die kristallisation eines geschmolzenen molekülkomplexes aus hochmolekularem polyoxyethylen und harnstoff
Authors: Bogdanov Bogdan , Michailov Marin , Uzov Christo , Gavrailova Girka 
Published: April 2003

AbstractDie Strukturveränderungen eines Molekülkomplexes (MK) aus Polyoxyethylen und Harnstoff beim Abkühlen aus dem geschmolzenen Zustand werden kalorimetrisch und röntgenographisch untersucht. Es wird festgestellt, daß eine polymorphe Hochtemperaturform des MK entsteht, die beim Abkühlen in die bekannte Kristallform des MK mit hexagonaler Kristallmodifikation übergeht.
Synthese und koagulationsverhalten von hydrophilen copolymeren des acrylnitrils
Authors: Fritzsche Peter , Dautzenberg Herbert , Nötzel Petra , Rother Gudrun 
Published: April 2003

AbstractCopolymere des Acrylnitrils (AN) mit variabler Molmasse bzw. mit variablem Anteil von Acrylsäuremethylester (ASME) und Natriumallylsulfonat (NaAS), Acrylamid (AA), Itaconsäure (IS), Polyethylenglykolacrylat (600) (PEGA), Vinylacetat (VA), Acrylsäure‐2‐hydroxyethylester (HEE) oder Natrium‐2‐acrylamido‐2‐methylpropansulfonat (NaAMPS) wurden hergestellt, wobei die erforderlichen Polymerisations‐bedingungen mit Hilfe eines mathematischen Polymerisationsmodells ermittelt wurden.Die Fällungsuntersuchungen mit der Methode der Lichtstreuung zeigten, daß NaAS und NaAMPS einen dominierenden Einfluß haben. Bei Acrylnitril‐Homopolymeren tritt eine harte Fällung auf, und die entstehenden Partikel haben eine Dichte zwischen 0,2 und 0,4 g/cm3. Zunehmender NaAS‐bzw. NaAMPS‐Gehalt führt ab einem Gehalt von beispielsweise ca. 0,8 Gew.‐% NaAS im Monomergemisch zu einer weichen Fällung, bei der hochgequollene Partikel mit einer Dichte in der Größenordnung von < 1.10−2 g/cm3 entstehen. Ein Einfluß der Molmassen und des ASME‐Gehaltes Konnte nicht nachgewiesen werden. Beim Acrylnitril/Acrylamid‐System genügen offensichtlich 0,5 Gew.‐% Allylsulfonat im Monomeransatz, um eine stabile, weiche Fällung unter Bildung hochgequollener Strukturen zu gewährleisten. Alle Proben mit den übrigen hydrophilen Cokomponenten zeigen ohne NaAS bzw. NaAMPS‐Comonomer ein hartes Fäungsverhalten mit wenig gequollenen Partikeln.
DSC investigation on the thermal degradation of PVC in blends
Authors: Braun Dietrich , Kömmerling Stefan 
Published: April 2003

AbstractThe thermal degradation of poly(vinyl chloride) (PVC) has been studied by differential scanning calorimetry (DSC). Due to crosslinking, the glass transition temperature (Tg) of PVC raises during the degradation. The thermal degradation of PVC has also been studied for heterogeneous 1:1 (w/w) blends of PVC with polystyrene (PC), poly(styrene‐co‐acrylonitrile) (SAN), high‐impact PS (poly(styrene‐g‐butadiene)) (HIPS) and poly(SAN‐g‐butadiene) (ABS). Tg of the PVC phase raises slower during degradation in the PVC/PS‐blend, whereas in the other blends the crosslinking is accelerated, due to a negative influence of the double bonds and/or the nitrile groups on the thermal stability of PVC. Since most methods use the determination of eliminated HCl to study the degradation of PVC, the DSC method is very useful in investigations on PVC‐containing polymer blends, if there might be a reaction of HCl with one of the blend components.
Polyacetal/poly(tetrafluoroethylene) blends, I. The effect of Na‐treated poly(tetrafluoroethylene) on polyacetal
Authors: Chiang Wen‐Yen , Huang Chi‐Yuan 
Published: April 2003

AbstractThe various properties of the blends of polyacetal (POM) with up to 20 wt.‐% chemically surface‐treated poly(tetrafluoroethylene) (CPTFE) were investigated and compared with those of POM/PTFE blends. The PTFE is added to POM to improve the wear properties, however, the mechanical properties of POM/PTFE blends decrease with increasing PTFE content, but tensile strength and Young's modulus of POM/CPTFE blends are more than 2 times higher than that of the POM/PTFE blends. SEM shows that the size of inherent agglomerative PTFE is in the range of 30 to 100 μm. The particle size of major CPTFE dispersed in POM is smaller than 1 μm.
Synthesis and properties of cationic amine‐epoxy adducts and their use in electrodeposition, II. Diethanolamine/diketimine terminated cationic epoxy resins with pendent 2‐ethylhexanol‐blocked TDI groups
Authors: Yang Chin‐Ping , Chen Yahn‐Haur 
Published: April 2003

AbstractA diglycidylether of bisphenol A epoxy resin (DGEBA) was first reacted with 2,4‐toluene diisocyanate partially blocked with 2‐ethylhexanol (2‐EH P. B. TDI) to form modified epoxy resins, and subsequently reacted with different molar ratios of diethanolamine and bis(2‐methylisobutylketiminoethyl)amine (DKI) (used as ring opening agents) to give diethanolamine/diketimine terminated resins. These resins were hydrolyzed and neutralized with acetic acid to give cationic resins containing various contents of primary amine groups in the terminal polymeric chain. These cationic resins can be dissolved in a suitable solvent and mixed with deionized water to obtain emulsions. The electrodeposition properties and characteristics of the resulting cationic resins were investigated in detail. The effects of hydrophobic solvents, such as hexyl cellosolve (HCS) and toluene, on the deposition properties of the emulsions are discussed.
Relation between polymer surface tension and orientation of thermotropic liquid crystals
Authors: Seeboth Arno M. 
Published: April 2003

AbstractThe orientation (tilt angle φ) of thermotropic liquid crystals (LC) on the interface to a polymer‐coated surface is not only determined by the numerical value \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S} {\rm = \gamma }_{\rm S}^{\rm d} {\rm + \gamma }_{\rm S}^{\rm p} } \right)$\end{document} of the substrate surface tension. However, the ratio between the dispersive and the polar part of \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm\gamma }_{\rm S}^{\rm d} {\rm : \gamma }_{\rm S}^{\rm p} } \right)$\end{document} also influences the LC orientation on the substrate surface. A polyimide and an amide‐modified styrene/maleic anhydride copolymer were used as polymers.
On the polymerization of acrylonitrile in the presence of some unsaturated triazine derivatives
Authors: Konstantinova Temenoujka , Grabchev Ivo 
Published: April 2003

AbstractThe polymerization of acrylonitrile in the presence of some unsaturated, triazinebased fluorescent brighteners (FB) has been investigated. It was found colourimetrically that more than 80% of the FB is incorporated in the polymer. The initial concentration of 0.1 wt.‐% is sufficient to obtain a good bleaching effect without significant decrease of the molecular weight.
Photoinitiated surface grafting of synthetic fibers, III. Photoinitiated surface grafting of poly(ethylene terephthalate) fibers
Authors: Feng Zhenguo , Rånby Bengt 
Published: April 2003

AbstractPhotoinitiated surface grafting of acrylic acid (AA), acrylamide (AM) and 4‐vinyl pyridine (VP) onto poly(ethylene terephthalate) (PET) fibers (a commercial textile yarn) has been studied using benzophenone (BP) as photoinitiator. A continuous process as previously described has been applied, which involves presoaking of the PET yarn in a solution of initiator and monomer in acetone and UV irradiation in nitrogen atmosphere. The resulting grafted polymer on the fiber surface has been analyzed by ESCA, titration of carboxy groups (grafted AA), and dye absorption. The relative ESCA intensities (RI) of O1s/C1s and N1s/C1s are used as measure for grafted AA, AM and VP, respectively, after recording the RI‐values for ungrafted fibers. For grafting with AA, the RI‐values increased from 32.8% (background) to 48.6% after 20 s irradiation time. The amount of carboxy groups measured by titration increased from 0.045 to 0.106 mmol/m2. Assuming an even coverage of grafted AA polymer, this means a grafted layer of 4.8 nm thickness. After grafting, the adsorption of the dye Crystal Violet (CV) from aqueous solution increased by about 3 times. With AM as monomer, the RI‐values increased from 2.6 (background) to 14.8% and the adsorption of a direct dye Sirius Lichtbordo B‐LL increased by about 6 times. With VP as grafted monomer, the RI‐values increased from about 2.6 (background) to 5.1% and the adsorption of the direct dye increased by about 4 times.
Studies on hexolic anhydride based polyesters, II. Thermogravimetric analysis
Authors: Sivasamy P. , Palaniandavar M. , Vijayakumar C. T. 
Published: April 2003

AbstractUnsaturated polyesters based on hexolic anhydride (5,6,7,8,9,9‐hexachloro‐1,2,3,4,4a,5,8,8a‐octahydro‐5,8‐methanonaphthalene‐2,3‐dicarboxylic anhydride), maleic anhydride, phthalic anhydride, cis‐2‐butene‐1,4‐diol, 2,3‐dichloro‐2‐butene‐1,4‐diol and 2,3‐dibromo‐2‐butene‐1,4‐diol were synthesized. The thermal behaviour of the polyesters was studied using thermogravimetric technique. The results were compared with those available for other hexolic anhydride and HET‐acid (1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid) based polyesters. The direct study and comparative study of the polyesters revealed that the bromodiol is prominent in increasing the flame retardant character of the polyesters in which it is incorporated; alkenic diols are inferior compared to saturated diols regarding the thermal stability of the polyesters; as the number of carbon atoms in the saturated diol increases, the stability and flame retardancy of the polyesters decrease; branching in the diol part decreases the stability of the polyesters, with hexolic anhydride based polyesters being thermally more stable than HET‐acid based polyesters.
Oberflächenstrukturierung polymerer Fasern durch UV‐Laserbestrahlung. 13. Oberflächenstrukturierung von Hochleistungsfasern
Authors: Kesting Wolfgang , Knittel Dierk , Bahners Thomas , Schollmeyer Eckhard 
Published: April 2003

AbstractDie Oberflächenbehandlung von unterschiedlichen Hochleistungsfasertypen mit gepulstem UV‐ Laserlicht wird untersucht. Bedingt durch die hohen UV‐Absorptionskoeffizienten dieser Materialien wird der bekannte Effekt des UV‐laserinduzierten Abtrags (Ablation) bei allen Fasern beobachtet. Zusätzlich werden durch die Relaxation der orientierten Makromoleküle charakteristische Strukturierungen auf der Faseroberfläche ausgebildet. Für einen möglichen kontrollierten und gezielten Einsatz dieser physikalischen Oberflächenmodifizierung in textilen Anwendungen werden die gnaunen Bedingungen der Laserbestrahlung ermittelt und beschieben. Darüber hinaus werden geeignete Konstanten der Laserbearbeitung wie Ablationsschwellenenergie, Ätzraten und Strukturierungskonstanten für verschiedene Fasertypen bestimmt.
Studies on hexolic anhydride based polyesters, III. Mechanistic and comparative aspects of the product distributions in the thermal degradation
Authors: Sivasamy P. , Palaniandavar M. , Vijayakumar C. T. 
Published: April 2003

AbstractTwo systems of unsaturated polyesters based on maleic anhydride, phthalic anhydride, hexolic anhydride (5,6,7,8,9,9‐hexachloro‐1,2,3,4,4a,5,8,8a‐octahydro‐5,8‐methanonaphthalene‐2,3‐dicarboxylic anhydride) and 2‐butene‐1,4‐diol or 2,3‐dichloro‐2‐butene‐1,4‐diol were synthesized. The polyesters were pyrolysed under programmed heating from 40° to 400°C at a rate of 10 K/min. The volatile pyrolysates were separated and identified by combined gas chromatography/mass spectrometry. The formation of anhydrides, diols, hydrocarbons, chloro compounds and polychlorinated cyclopentadiene compounds etc., is explained in the light of single and double β‐scission, acyl‐oxygen and alkyl‐oxygen bond fission and carbon‐carbon bond homolysis mechanisms. It is observed that β‐scission plays a vital role in the primary degradation process of polyesters. The decreasing number of β‐hydrogens in the diol part of the polyester is reflected in the quantity of anhydrides ejected from the polymer backbone. Further it is observed that hexachlorocyclopentadiene and related compounds are ejected from the hexolic anhydride set free during pyrolysis and not from the hexolic moiety incorporated in the polymer backbone. An approximate calculation shows that about 75% of the total amount of maleic anhydride, formed in the pyrolysis of saturated diol based polyesters having fullest number of β‐hydrogens in the diol part, is derived from β‐scission and the rest via alkyl‐oxygen bond fission mechanism. A similar observation is also noted‐indirectly for the formation of hexolic anhydride.
Dielectric study of acetylated cotton cellulose and saponified cellulose acetate
Authors: Saad Gamal R. , Botros Maged G. , Nessim Refaat I. 
Published: April 2003

AbstractDielectric relaxation data are reported at frequencies of 0.1 – 10000 kHz over a temperature range of 10–80°C on cellulose acetates of different degrees of substitution, and on saponified cellulose acetate. The acetyl substitution is found to remove the low‐frequency relaxation process, γ, previously observed in medicated cotton cellulose, and to affect the other higher‐frequency process, β, in different ways, depending on the acetyl content. Conversely, saponification of cellulose acetate leads to the reversion of these two processes but with different features.Analysis of the absorption bands is made, and an assessment of the results obtained is given.
Removal of methyl orange by a system of insoluble chloromethylated poly(styrene‐co‐2‐methyl‐2‐oxazoline)
Authors: Tashiro T. , Thirvenkatam P. 
Published: April 2003

AbstractA study was made of the removal of methyl orange (MO) solutes in water by the reaction product (CMPS‐MeOZO) of chloromethylated, divinylbenzene‐crosslinked polystyrene (CMPS) with 2‐methyl‐2‐oxazoline (MeOZO).The removal behavior was examined with regard to the conformity to the Freundlich adsorption formula and the Klotz equation, and noted to conform in wider range of initial concentration of MO to the former than to the latter. Removal rates and amounts removed were larger in CMPS‐MeOZO(3)‐Hy (hydrolyzate of CMPS‐MeOZO(3)) than in CMPS‐MeOZO(4). This is attributable to the less cationic charge of the nitrogen atoms in poly(N‐acetyliminoethylene) than that of poly(iminoethylene) side chains.
Metallization of polyacrylonitrile by reduction of polymer‐incorporated metal ions
Authors: Yosomiya Takatoshi , Ono Hitoshi , Yosomiya Ryutoku 
Published: April 2003

AbstractThe film properties and ionic conductivity behavior of polyacrylonitrile (PAN) containing various metal salts were investigated. Further, with a newly developed process, it was possible to cover the surface of polymer with a metallic layer. From water contact angle measurements it was found that the surface structure of PAN containing metal salt was greatly affected by properties of the material in contact with during film preparation. Ionic conductivity behaviors near Tg differed between the PAN containing a metal chloride and that containing a metal perchlorate; the activation energy for the rubber‐like state (ϵr) was greater than that for the glassy state (ϵg) with the former and ϵr < ϵg with the latter. It was clarified that a metal layer was formed on the polymer surface at a relatively low temperature by a reduction treatment with NaBH4 aqueous solution.