bluuebunny/crossref_metadata_2025 huggingface dataset:
Allylic polymers from resin acids
Authors: Bicu Ioan , Mustaţǎ Fǎnicǎ
Published: April 2003

An unsaturated adduct has been synthesized by the Diels‐Alder reaction between resin acids and diallyl maleate. The obtained polymerizable product can be used both as monomer in the formation of allyl polymers and crosslinking agent. The monomer and its polymers were investigated by usual physical and chemical methods. The synthesized polymers present a linear structure, possibly associated with intramolecular cyclization at low molecular weights, or a three‐dimensional structure at high conversions. They are fairly thermostable substances with carboxylic groups in the polymer chain.
Toughened thermosetting bismaleimides: Molecular structure, morphology and mechanical properties
Authors: Abbate M. , Martuscelli E. , Musto P. , Ragosta G.
Published: April 2003

A 4,4′‐bis(maleimido)diphenylmethane resin was modified by adding a thermoplastic poly(ether imide) commercially available as Ultem 1000. A second system investigated was formed by a Kerimid resin and a maleimido‐terminated butadiene‐acrylonitrile copolymer (ITBN). For this system the kinetics of the curing process of the blend matrix with and without the rubber modifier was investigated at different temperatures by FTIR spectroscopy.

A marked increase of the toughness parameters Kc and Gc was found for both the investigated systems. However, morphological analysis showed a complete phase separation and a complex morphology for the thermoplastic modified resin, while a homogeneous, single‐phase system was obtained after rubber modification by ITBN.
Radical polymerization of poly(butyl acrylate) in the presence of poly(L‐lactic acid), 1. Synthesis, characterization and properties of blends
Authors: Avella Maurizio , Errico Maria Emanuela , Immirzi Barbara , Malinconico Mario , Martuscelli Ezio , Paolillo Livio , Falcigno Lucia
Published: April 2003

Poly(L‐lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n‐butyl acrylate, via water suspension polymerization onto poly(L‐lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross‐linked.
Products of the reaction of 4,4′‐bis(mercaptomethyl)benzophenone with halogenalkane acids and halogenalkane diols as new monomers
Authors: Podkościelny Wawrzyniec , Kultys Anna
Published: April 2003

A few new thiodicarboxylic acids and thiodiols were obtained by condensation reaction of 4,4′‐bis(mercaptomethyl)benzophenone (BMMB) with some halogen acids or halogen alcohols, respectively, in aqueous sodium hydroxide solution.

By melt polycondensation of one of these acids, i.e. benzophenone‐4,4′‐bis‐(methylthioacetic acid) (BBMTAA) with 1,5‐pentanediol, a new linear polyester was obtained, and by melt polyaddition of one of these diols, i. e. benzophenone‐4,4′‐bis(methylthiohexanol) (BBMTH) with hexamethylene diisocyanate (HDI) a new linear polyurethane was obtained.

The structures of monomers and polymers were confirmed by elemental analysis and FT‐IR and 1H NMR spectroscopy. The polymers were studied to describe their physicochemical, thermal and mechanical properties.
Tin‐coupled styrene‐butadiene rubbers (SBRs). Relationship between coupling type and properties
Authors: Quiteria Valentín Ruiz‐Santa , Sierra Carmen A. , Gómez‐Fatou Jose M. , Galán Carmen , Fraga Luisa M.
Published: April 2003

Following the development of new SBRs for tyre applications, several kinds of tin‐polymer bonds (styryl‐, butadienyl‐, isoprenyl‐ and α‐methylstyryltin) have been studied, in both branched and linear chains.

Dynamic‐mechanical properties of the carbon black vulcanizates have been analyzed to establish a relationship between structural parameters of polymers and compound properties. The filler‐polymer interaction parameter, defined by a ratio of mechanical and dynamic terms, has been used for the evaluation of the compounds. The introduction of different types of tin‐polymer bonds, in branched and linear chains of the SBRs, implies an improvement in the hysteresis properties of the vulcanizates as well as a modification of the interaction parameter.
A novel spin‐finishing method for antistatic modification of polyester fiber. Surface reaction onto amine‐containing copoly(amide‐ethers) blended with polyester fiber
Authors: Sano Yoshiyuki , Lee Chan Woo , Kimura Yoshiharu , Saegusa Takeo
Published: April 2003

Copoly(amide‐ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt‐spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo‐betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide‐ether) was melt‐spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on‐line with spinning and drawing within a short reaction time, this modification technique is called “spin‐finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity.
Effect of accelerated exposure conditions on the photodegradation of BPA polycarbonate/ABS blends
Authors: Pickett James E. , Barren James P. , Oliver Richard J.
Published: April 2003

A BPA polycarbonate/ABS blend containing 2% TiO2 was exposed to xenon are irradiation under SAE J 1885 conditions (quartz/borosilicate filters). “CRD” conditions (borosilicate/borosilicate filters), and ASTM D4459–86 conditions (borosilicate/soda lime filters). The results are consistent with the conclusion that polycarbonate dominates the photochemistry of polycarbonate/ABS blends under SAE J1885 and CRD xenon are exposure conditions. Exposure under ASTM D4459–86 conditions produced results similar to CRD conditions with some additional contribution attributable to the ABS component. The “activation spectrum” of PC/ABS blends under CRD conditions closely resembled the sum of the activation spectra of ABS and PC determined under similar conditions. The well‐known change in mechanism that occurs when polycarbonate is exposed to light with wavelengths < 300 nm was manifested by increased rates of yellowing, surface erosion. and loss of gloss under SAE J 1885 conditions. Because of the mechanism change, testing under quartz/borosilicate filtered xenon are exposure cannot be considered to be appropriate for polycarbonate‐containing formulations.
Degradation of ultra high molecular weight polyethylene in vivo
Authors: Costa L. , Luda M. P. , del Prever E. M. Brach
Published: April 2003

Mechanical and thermal oxidation of UHMWPE used in the preparation of prosthetic implants is studied and the mechanisms of degradation are reported. Oxidation of new and retrieved prosthetic implants are studied by IR microscopy and clear evidence of oxidation in vivo is shown.
The influence of flame retardant structure on UV stabilization approaches in polypropylene
Authors: Gray Robert L. , Lee Robert E.
Published: April 2003

UV stabilization of polymer systems containing brominated flame retardants has proven to be a difficult technical challenge. Generation of acidic products during processing or exposure can cause a catastrophic deactivation of the Hindered Amine Light Stabilizer (HALS). An understanding of the mechanism for bromine generation from aliphatic and aromatic based flame retardants has lead to formulation approaches based on flame retardant structure. In formulations containing aromatic brominated flame retardants, combinations of UV absorbèrs and a new class of siloxane HALS provide the highest level of UV stabilization to date. Alternatively, bicomponent fiber spinning technology can also provide outstanding UV resistance at significantly lower levels of stabilizers than that used in the monocomponent formulation approach.
Photoinitiated degradation of polymers by metal salts‐recent developments
Authors: Kaczmarek H. , Rabek J. F.
Published: April 2003

This paper reexamines the role of transition metal salts (mainly CuCl2 and FeCl3) in the photooxidative degradation of polymers. Metal salts belong to external impurities originated in polymers from synthesis, processing, storage, contacts with metal corrosion, etching reactions, etc. Transition metal salts in the presence of water become very reactive species. In such metal chlorides as CuCl2 and FeCl3 UV and/or visible light irradiation causes an electron‐transfer from Cl− to metal cation. The produced chlorine radical can abstract hydrogen atom from a polymer molecule giving polymer alkyl radical. which is easily oxidized in air. This process is accompanied with a chain scission reaction which is responsible for the degradation of a polymer. Mechanisms of these reactions are discussed in detail.
Polymer bound HALS‐expectations and possibilities
Authors: Malik Ján , Ligner Gilbert , Ávár Lajos
Published: April 2003

The work confronts the traditional opinion on the physical aspects of the HALS efficiency with the available experimental reality. The results indicate that the generally accepted importance of additive's migration may need to be reconsidered. Based on the experimental evidence, three empirical requirements for an effective stabiliser are formulated: high solubility, minimal diffusion, high homogeneity of distribution of active species. Chemical grafting of a low molecular stabiliser is suggested to meet the defined empirical requirements. The results achieved with the polymer bound HALS (PBH) prepared by reactive processing technology confirm the expectations. The stabilisation efficiency of PBH significantly outperforms the conventional low molecular and oligomeric stabilisers.
Polymers degradable under environmental conditions through end‐modification of poly(α‐methylstyrene) derivatives
Authors: Nagasaki Yukio , Yamazaki Noriyuki , Kato Masao
Published: April 2003

To induce degradabilities in polymers in response to environmental conditions, the end‐modification reactions of poly(α‐methylstyrene) derivatives were carried out. When diphenylphosphine chloride was used as a modifier for the living end of para‐substituted PMS, the coupling efficiency was ca. 50%. 2‐Phenylallyl halide derivatives such as 2‐phenylallyl bromide, 2‐(4‐tolyl)allyl bromide, and α‐trifluoromethylstyrene were found to be suitable end‐modification agents. For example, ω‐2‐phenylallyl PMS was prepared with almost quantitative functionality by the reaction of the living PMS with 2‐phenylallyl bromide. In a similar way, ω‐3,3‐difluoro‐2‐phenylallyl and ω‐2‐(4‐tolyl)allyl PMS derivatives were synthesized. Based on thermogravimetric analysis, onset of the degradation temperature of the end‐modified PMS derivatives decreased in the following order: ω‐hydrogen‐ > ω‐3,3‐difluoro‐2‐phenylallyl‐ > ω‐2‐phenylallyl‐ > ω‐2‐(4‐tolyl)allyl‐PMS. Actually, the onset temperature of ω‐2‐(4‐tolyl)allyl‐PMS derivatives was 50°C lower than that of ω‐H‐PMS derivatives. These results indicate that the active species is produced effectively at the end unsaturated bond, which initiates the depolymerization of the polymer at rather low temperatures. Ionic degradation of these polymers was also investigated using butyllithium as an anionic initiator and methanesulfonic acid as a cationic initiator. Tendencies similar to the thermal degradation were observed. Therefore, it is concluded that a 2‐phenylallyl substituent at the end of the PMS chain induces effective degradation through several mechanisms such as radical, anionic and cationic depolymerization reactions.
Thermal degradation of polystyrene in different environments
Authors: McNeill I. C.
Published: April 2003

Several aspects of the thermal degradation of polystyrene are highlighted in this communication. The factors involved in determining the ratio of volatile to tar fraction products in the degradation of the pure polymer are examined, leading to the conclusion that the initial melt viscosity plays an important role in determining the balance between intra‐ and intermolecular transfer. The effect on the degradation of polystyrene of the presence of a second polymer is discussed. For polystyrene‐polybutadiene and polystyrene‐polyisoprene blends, stabilisation is observed, which is attributed to radical scavenging. The thermal degradation behaviour of polystyrene in the presence of oxygen has been investigated, with and without an antioxidant additive. Products have been characterised for oxidative conditions and the kinetics of degradation have been studied.
Chemiluminescence in thermal oxidation of ABS
Authors: Parikh Sunil S. , Zlatkevich Lev
Published: April 2003

Two concepts in the chemiluminescence research‐the heterogeneous model and the kinetic approach‐are discussed. The analysis of published data obtained by a highly sensitive photon‐counting system reveals the contradictory nature of the heterogeneous model and proves its inconsistency. On the other hand, the kinetic approach has been successfully applied to evaluation of thermal oxidation in a variety of systems, ABS compositions in particular. Emulsion grade ABS were found to be essentially less stable than ionic mass polymerization products. Among the antioxidants studied, Santonox R is clearly more efficient than Irganox 1076. In emulsion grades the superiority of Santonox R to Irganox 1076 is reflected primarily in larger induction period, while in ionic resin it is mostly due to smaller oxidation rate constant values. The introduction of UV stabilizers by themselves has no influence on durability in either ionic or emulsion resins. Similarly to systems without UV stabilizers, Santonox R is more efficient than Irganox 1076 in mixtures with UV stabilizers as well. The comparative study of various ABS‐coloring agent compositions by chemiluminescence and DSC reveals much greater sensitivity of the former. While DSC lets one make only a trivial conclusion that the introduction of an antioxidant improves stability, chemiluminescence shows the differences in durability as large as 3 to 4 times for the samples DSC fails to distinguish. In addition, chemiluminescence furnishes a significant insight on the factors affecting stability. The DSC thermal oxidative stability data can be related to resistance to oxidation during processing, whereas the chemiluminescence results are expected to be useful in predicting materials' lifetime at service temperatures.
Polyelectrolytes with various charge densities: Synthesis and characterization of diallyldimethylammonium chloride‐acrylamide copolymers
Authors: Brand Fabien , Dautzenberg Herbert , Jaeger Werner , Hahn Mathias
Published: April 2003

The synthesis of defined polyelectrolyte models by radical copolymerization of diallyldimethylammonium chloride (DADMAC, M1) and acrylamide (AAM, M2) in aqueous solution is impeded by a large difference of the reactivity ratios (r1 ≪ r2) leading to a strong conversion dependence of the copolymer composition. For the synthesis of normally distributed polyelectrolytes of the same molecular weight with various charge densities, a general algorithm based on a feeded polymerization with dosage of the more reactive monomer was therefore developed.

Various copolymer compositions predictable by the Mayo‐Lewis equation and determined by chloride potentiometry were obtained. The sequence lengths distributions investigated by 13C NMR spectroscopy followed a Markov statistic of first order. The 13C NMR spectroscopy is shown as alternative method to gravimetry in determining reactivity ratios. The partial specific volumes and the refractive index increments of the copolymers correspond to the additivity principle. Further molecular and dynamic parameters are determined by membrane osmometry, static and dynamic light scattering, analytical ultracentrifugation, gel permeation chromatography, and viscometry. Monomodal molecular weight distributions, small polydispersities only for copolymers with high content of DADMAC are obtained at given comonomer and initiator concentration. The number‐average molecular weight is almost constant for a broad copolymer composition range.

Rg‐M and [η]‐M relations could be established for practical use at high ionic strength, despite the various chemical compositions. Some indications for a higher stiffness of copolymers with high contents of DADMAC despite the shielding of the electrostatic interactions are, however, given. At low ionic strength the electrostatic interactions prevail. Their influence with increasing charge density is stronger on the Huggins constants (intermolecular interactions) than their effect on the intrinsic viscosities (intramolecular interactions).
Mechanical properties of poly(propylene) filled with calcium carbonate of various shape
Authors: Mitsuishi Kazuta
Published: April 2003

Calcium carbonate of various particle shape (CaCO3, sphere, cube, needle) treated with alkyl dihydrogen phosphate ester (APEN, CnH2n+1OPO(OH)2, n = 1, 4, 8, 10, 12) and poly(propylene) (PP) were mixed on a two roll mill. The effect of carbon number of APEN on the mechanical properties (tensile elongation, tensile strength, impact strength, yield stress) and adhesion between PP matrix and various CaCO3 particles and the effect of CaCO3 shape on the storage modulus of elongated PP/CaCO3 has been investigated.

The tensile elongation, impact strength and adhesion of PP‐CaCO3 interface increased with carbon number of APEN (n ≦ 10) for needle and cube type, but the dependence of tensile properties on APEN carbon number is not clearly recognized for the sphere type.

The relative storage moduli of elongated PP/CaCO3, E/E E – modulus of elongated PP/CaCO3 (untreated); E – modulus of elongated PP matrix could sufficiently be described with a modified Halpin‐Tsai equation, which contains the factors of (i) polymer matrix orientation, (ii) particle effect (content, modulus, aspect ratio), and (iii) void volume at polymer‐filler particle interface.
New preparation method of poly(amide‐imide)s using direct polycondensation with thionyl chloride and their characterization
Authors: Hong Young‐Taik , Jin Moon Young , Suh Dong Hack , Lee Jae‐Heung , Choi Kil‐Yeong
Published: April 2003

A study for the development of a new, economical manufacturing process for high‐molecular‐weight poly(amide‐imide) (PAI) was performed via direct polycondensation of trimellitic acid anhydride (TMA) or diimide diacids (DIDAs) with aromatic diamines using an equimolar amount of thionyl chloride in NMP at relatively low temperatures. The polyamidation of DIDAs and diamines for head‐to‐head polymers (H‐PAIs) was sensitive to the reaction temperature and proceeded very quickly, 1 h was sufficient to complete the reaction. The highest value of inherent viscosity, ηinh, of 72 mL g−1 was obtained by polymerization at room temperature. Also several randomly sequenced polymers (R‐PAIs) were prepared by polycondensation from TMA and diamines, followed by imidization with various methods, such as using TPP as a co‐condensing agent, azeotropic dehydration of polyamic acid (PAA) and solid‐state imidization from PAA. Solid state imidization from polyamic acids at 235°C gave satisfactory results with an inherent viscosity 58–85 mL g−1. Solvent content, imidization temperature and time were major controlling factors for the degree of imidization as well as for the molecular weight. Both H‐PAI and R‐PAI showed good mechanical properties with tensile strength of 118–131 MPa and Tg ranged between 263–299°C depending on the nature of monomers. The melt viscosity of the PAIs ranged between 7.4 · 103 and 4.5 · 103 Pa s for H‐PAI and R‐PAI respectively. These values are comparable to that of conventional PAI, Torlon® 4000T of 5.6 · 103 Pa s.
Study on the kinetics of interfacial polycondensation for polyarylate
Authors: Wang Chung‐Yu , Wang Ding‐Chang , Chiu Wen‐Yen , Chen Leo‐Wang
Published: April 2003

For the synthesis of polyarylate by interfacial polycondensation of bisphenol A with terephthaloyl/isophthaloyl dichloride, the kinetic mechanism was studied through the detection of the concentration of bisphenolate in the aqueous phase by UV spectrometry. The mechanism consists of three steps: 1. the transportation of bisphenolate in the aqueous phase, 2. the transfer of bisphenolate through the interface followed by its transportation in the organic phase, 3. the reaction of bisphenolate with the phthaloylic dichloride in the organic phase. The reaction of bisphenolate with the phthaloylic dichloride in the organic phase is the rate‐determining step. The influence of the concentration in either the aqueous phase or the organic phase and of the quantity of the phase transfer agent on interfacial polycondensation were studied.
Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten, Teil 1: Grundlagen
Authors: Denter Ulrike , Buschmann Hans‐Jürgen , Knittel Dierk , Schollmeyer Eckhard
Published: April 2003

Ein neues Konzept zur Modifizierung von Faseroberflächen durch permanente Fixierung supramolekularer Verbindungen wird vorgestellt, und das Prinzip der selektiven Komplexierung wird erklärt. Als für die Behandlung grundsätzlich geeignete Liganden werden insbesondere Cyclodextrine, Azakronenether, Calixarene, Cyclotriveratrylene und Fullerene hinsichtlich ihrer chemischen Struktur sowie ihrer komplexierenden Eigenschaften beschrieben. Einige erreichbare Oberflächeneffekte werden hervorgehoben.
Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten, Teil 2: Cyclodextrine
Authors: Denter Ulrike , Buschmann Hans‐Jürgen , Knittel Dierk , Schollmeyer Eckhard
Published: April 2003

Mit herkömmlichen Verfahrenstechniken der Textilveredlung werden ausgewählte Cyclodextrinderivat über geeignete funktionelle Gruppen permanent auf verschiedenen Fasermaterialien fixiert. Einige der durch die Oberflächenmodifizierung beeinflußten Eigenschaften der Polymeren werden im einzelnen diskutiert. Insbensondere kann für mehrere Liganden gezeigt werden, daß die verankerten molekularen Hohlräume nicht die Fähigkeit verlieren, hydrophobe organische Verbindungen zu komplexieren. Somit lassen sich durch den Einschluß spezifischer Wirksubstanzen spezielle funktionelle Eigenschaften erzielen.
Oxidative polymerization of acrylamide in the presence of L‐threonine
Authors: Özeroǧlu Cemal , Güney Orhan , Mustafaev Mamed I.
Published: April 2003

L‐threonine/Ce(IV) salts and L‐threonine/KMnO4 initiator systems were used for the polymerization of acrylamide, resulting water‐soluble poly(acrylamide) which contains hydroxy amino acid end groups. The dependence of polymerization yields and molecular weights of the polymers on the mole ratio of acrylamide (AA)/L‐threonine (Thr), the polymerization time, the temperature and the concentration of sulfuric acid was investigated. The decrease in the mole ratio of acrylamide to L‐threonine resulted in a decrease in the molecular weight of poly(acrylamide) which contains L‐threonine end groups. The maximum yield has been obtained at the mole ratio of nAA/nThr = 250, further decrease in the mole ratio of acrylamide to L‐threonine resulted in a decrease in the yield of acrylamide polymer. With an increasing sulfuric acid concentration, the polymerization yield decreases. Ce(IV) and Mn(IV) reduced to Ce(III) and Mn(II), respectively, in the polymerization reaction. The amounts of polymer‐bound Ce(III) and Mn(II) were determined. The composition of the polymerization products was investigated.
Celluloseether als Trennschichten hydrophiler Polymermembranen
Authors: Schmidt Matthias , Peinemann Klaus‐Viktor , Paul Dieter , Rödicker Herbert
Published: April 2003

Es wird die Entwicklung hydrophiler Polymermembranen diskutiert, die nach Beschichtung mit Celluloseethern und anschließender Vernetzung auf den asymmetrischen Trägermembranen interessante Permeations‐ und Trenneigenschaften bei hervorragenden chemischen Stabilitäten, vor allem beim Membrantrennverfahren der Nanofiltration, aufzeigen. Weiterhin werden Aussagen zu den Gastrenneigenschaften der Celluloseetherkompositmembranen getroffen.

Erläutert werden die Permeations‐ und Trenndaten der Kompositmembranen in Korrelation zur Vernetzung der Celluloseether anhand verschiedener Einflußgrößen, was qualitative und gegebenenfalls quantitative Aussagen zum Vernetzungsmechanismus der Celluloseetherderivate erlaubt. Dabei stehen die Vernetzungstemperatur, der Einfluß der katalysierenden Wasserstoffionen und bedingt die Vernetzungszeit im Vordergrund. Abgerundet werden die Arbeiten durch Ermittlungen rheologischer Daten, die in Zusammenhang zu den Vernetzungsreaktionen und damit zu membranspezifischen Größen stehen.

Infolge der hervorragenden chemischen Stabilität der Celluloseether werden Einsatzmöglichkeiten der Kompositmembranen zur Nanofiltration niedermolekularer Verbindungen aus organisch hochbelasteten Systemen beschrieben.
Etching of a low‐density polyethylene film by fuming nitric acid
Authors: Bag Dibyendu S. , Kumar V. Pradeep , Maiti Sukumar
Published: April 2003

Low‐density polyethylene (LDPE) films were treated with fuming nitric acid (FNA). The surface characteristics and also the insertion of polar groups like on the etched LDPE film surface were measured by SEM, IR and XPS analyses, respectively. The mechanical performance of a laminate of the etched film with epoxy resin and also the printability of the etched film surface were tested and compared with the unetched sample. The surface roughening and the presence of polar groups enhance the mechanical strength of the laminate of FNA‐treated film due to mechanical interlocking and chemical interaction. The printability of the treated film surface is also superior to that of the untreated LDPE film surface.
Polyester networks based upon epoxidized and maleinated natural oils
Authors: Warth Holger , Mülhaupt Rolf , Hoffmann Botho , Lawson Sonya
Published: April 2003

Novel families of flexible, semiflexible and rigid crosslinked polyesters were prepared from modified natural oils such as soybean, rape‐seed and linseed oil. Maleinated oils were used as anhydride‐functional curing agents of epoxy resins such as bisphenol‐A‐diglycidylether and epoxidized natural oils. A new class of unsaturated polyester resins was based upon maleic anhydride, epoxidized natural oils and styrene. The resulting thermosetting polyesters were reinforced with natural fibers such as hemp and flax fibers. The influence of molecular architectures, curing conditions and formulations on thermal, mechanical and morphological properties were investigated.
X‐ray diffraction of thermotropic liquid‐crystalline copoly(vanillate‐4‐hydroxybenzoate‐ethyleneterephthalate)
Authors: Li Xin‐Gui , Huang Mei‐Rong
Published: April 2003

Precision X‐ray diffractometry was used to study directly the structure of as‐made films and fibers, which were uniaxially extruded from thermotropic liquid‐crystalline nematic melts of copolymers consisting of vanillate (V), 4‐hydroxybenzoate (B) and ethylene terephthalate (E) units with various molar ratios. The addition of a small amount of unit V (at most 5 mol‐%) to the well‐known poly(4‐hydroxybenzoate‐ethylene terephthalate) (B/E) polymer will produce an increase in orientation, but an addition of 15–34 mol‐% of unit V might result in the decrease of the orientation. The X‐ray diffractions of the oriented samples of V/B/E and B/E copolymers show a series of aperiodic intensity maxima on the meridian, which are consistent with that expected for a random sequence of the units. The equatorial scans exhibit single broad peaks centered at 0.437–0.446 nm due to intermolecular scattering. The meridional and equatorial maxima shift in position with the V/B/E ratio of the copolymers. The positions of the meridional maxima are slightly affected by spinning temperature. The linewidth of the most intense maximum at the spacing of 0.207 nm on the meridian was used to determine the correlation length of extended V/B/E copolymer chains. No discrete maxima are observed in both meridional and equatorial small‐angle X‐ray scattering curves.
Heat‐shrinkable films based on polyolefin waste
Authors: Viksne Armanda , Zicans Janìs , Kalkis Valdis , Bledzki Andrzej K.
Published: April 2003

Polyethylene wastes (low‐density polyethylene, high‐density polyethylene and their binary blends) were subjected to high‐energy radiation, using a 60Co gamma radiation source. The crosslinked materials thus obtained were processed to heatshrinkable films. Tensile strength could be sharply improved by increasing the dose up to 20 Mrad, simultaneously increasing the elongation at break of the most degraded PE waste. An increase of the degree of compatibility of LDPE and HDPE waste was also observed. All samples examined exhibit a “memory effect” after drawing at 130°C and cooling under tension followed by further heating under relaxed conditions. The value of shrinkage depended on the degree of degradation of the PE waste and on the irradiation dose.
Scanning electron microscopy analysis of the structure of thermotropic LC copolymers containing 2,7‐dioxynaphthalene or vanillate units
Authors: Li Xin‐Gui , Huang Mei‐Rong
Published: April 2003

The morphological structure of the fibers and rods of two series of thermotropic liquid‐crystalline copolymers made of 2,7‐naphthalenediol/terephthalic acid/4‐hydroxybenzoic acid(B)/poly(ethylene 2,6‐naphthalene dicarboxylate) and vanillic acid/B/poly(ethylene terephthalate), was systematically analyzed by using a high‐resolution scanning electron microscopy (SEM) fractographic method. Based largely on the SEM micrographs and visual appearance of the fracture surfaces, the fibers and rods were found to consist mainly of highly oriented needle‐like fibrils or lamellae, at which some finely split connections appear. The uniformity of the fibrils is somewhat dependent on the copolymer composition. The macrofibrils with diameters in the range of 10–50 μm and the microfibrils with diameters in the range of 50–90 nm have been observed. No separate phase is obvious in the fibers containing no more than 70 mol‐% of the B unit which has been confirmed by differential scanning calorimetry, but in the rods containing 75 mol‐% of the B unit a few less‐deformed phases related to B‐rich phase were occasionally observed.
Flockung und Entwässerung von Klärschlamm mit Hilfe von Polyelektrolyten
Authors: Parker Sylvia , Kulicke Werner‐Michael , Böhm Nicolai , Kötz Joachim , Jaeger Werner
Published: April 2003

Es wurde untersucht, wie ein ausgefaulter Klärschlamm durch eine optimale Flockungshilfsmittelzugabe zu mechanisch stabilen Flocken umgesetzt werden kann, so daß bei möglichst geringem Eintrag eine bestmögliche Entwässerung erzielt wird. Um dazu aussagekräftige, auf großtechnische Anlagen übertragbare Ergebnisse zu erhalten, wurde die Effektivität der Flockungshilfsmittel und der unterschiedlichen Flockungsverfahren in einer patentierten, mobilen, rechnergestützten Flockungs‐ und Entwässerungsapparatur getestet.

Der Klärschlamm wurde im Mono‐ und Dualverfahren mit bezüglich ihrer chemischen Struktur, Molmasse und Ladungsdichte (LD) eingehend charakterisierten kationischen (LD: 25–55 mol‐%; Mw: 1,5 · 106– 12,9 · 106 g mol‐1) und einem anionischen (LD: 36 mol‐%; Mw: 7,6 · 106 g mol‐1) Flockungshilfsmittel konditioniert. Im Gegensatz zu anderen bereits untersuchten Trüben konnte beim Klärschlamm weder eine Verbesserung der ohnehin sehr guten Entwässerbarkeit mittels kationischer Monoflockung (Laborversuch: 95 Gew.‐% Filtratausbeute nach 4 s), noch eine Verringerung der optimalen Einsatzmengen durch die Anwendung des Dualverfahrens erzielt werden. Darüber hinaus konnte gezeigt werden, daß die chemische Struktur und die Molmasse der untersuchten kationischen Polyelektrolyte einen weit größeren Einfluß auf die Entwässerungseffektivität besitzen als die Ladungsdichte in einem Bereich zwischen 25 und 55 mol‐%. Ferner erwies sich, daß die Konditionierungseffektivität der Polyelektrolyte mit steigender Molmasse zunimmt und die chemische Struktur hauptsächlich durch die Position der ladungstragenden Gruppe einen Einfluß auf das Entwässerungsergebnis zeigt.
Low‐molar‐mass and polymeric diazosulfonates as disguised diazonium ions for application as analytical reagents in quick assays
Authors: Matusche Peter , Nuyken Oskar , Voit Brigitte
Published: April 2003

Diazosulfonates decompose in water upon UV irradiation, forming diazonium salts as intermediates. Therefore, these compounds can be considered as diazonium ion sources, which are thermally very stable, easy to handle, and suitable for longtime storage. Several low‐molar‐mass diazosulfonates have been used in UV initiated azo coupling reactions with a large variety of phenols, naturally occuring substances, and drugs and the results were compared to those obtained with free diazonium ions. The conditions for a successful coupling reaction and the UV absorptions of the products were studied in detail. The concept could be transferred to polymers containing diazosulfonate functional groups. A preliminary application test proved the suitability of these polymers as analytical reagents in quick assays.
Makrogelierung von Polyacrylsäuredispersionen durch Vernetzung
Authors: Dauben Michael , Platkowski Kristina , Reichert Karl‐Heinz
Published: April 2003

Mit Blockcopolymeren stabilisierte Polyacrylsäuredispersionen mit ca. 100 nm großen Partikeln führen bei Reaktion mit Diglycidylethern oder Disäuredichloriden als Vernetzer ohne Schrumpfung zur Bildung von Makrogelen. Rasterelektronenmikroskopische Aufnahmen zeigen das Vorliegen einer aus den Partikeln aufgebauten dreidimensionalen Netzwerkstruktur. Die Kinetik der Vernetzungsreaktion wurde mit Hilfe der Differential‐Scanning‐Kalorimetrie untersucht. Das aufgestellte Modell berücksichtigt ein Verteilungsgleichgewicht des Vernetzers zwischen disperser und kontinuierlicher Phase und geht von einem Stofftransportprozeß der Vernetzermoleküle in das Partikelinnere aus. Mit Hilfe dynamisch‐rheologischer Messungen wurde gezeigt, daß das Gel ein kovalent vernetztes Gebilde darstellt. Frequenzabhängige Messungen der dynamischen Moduln während der Reaktion führten zu dem Schluß, daß sich das Partikelnetzwerk infolge einer reaktionskontrollierten Cluster‐Cluster‐Aggregation bildet. Mit Hilfe der dynamischen Lichtstreuung wurde festgestellt, daß kurz vor dem Gelpunkt eine Fraktion mit Clustergrößen um 1 bis 2 μm dominiert. Die zeitliche Entwicklung dieser Gebilde von Reaktionsbeginn an wurde mit Hilfe eines einfachen Modells auf Basis der stochastischen Methode beschrieben. Die Verankerung eines Palladium‐Kolloids in dem Partikelnetzwerk führte zu einem katalytisch aktiven Material.
Studies on the ultrasonic degradation of cellulose macromolecular properties
Authors: Marx‐Figini Marianne
Published: April 2003

The ultrasonic degradation of cellulose was investigated using a Bandelin‐Sonopuls‐HD 60 equipment with a frequency of 20 kHz and an output power of 22 W. As cellulose samples five polymeranalogous nitrates with an initial degree of polymerization DPη(0) between 400 and 7500 dissolved in ethyl acetate were used. The resulting macromolecular properties were determined viscosimetrically as well as by SEC (DPw, DPη, DPn, and distributions).

The results show the following characteristics, some of them have already been known for the ultrasonic degradation of synthetic polymers:

The rate of degradation is the more rapid the higher is DP0. At longer degradation times a limiting DP (DP∞) is observed. Materials with a DPη(0) < 700 do not degrade further. During degradation a very rapid narrowing of the distribution of DP takes place which is the more rapid the higher is DP0.

Correspondingly the polydispersity U decreases. The distributions show one maximum only during the whole degradation. The behaviour of polydispersity and distribution gives indications about the mechanism of scission of the molecules.

The possibility to use ultrasonication to produce cellulose samples with narrow distributions is discussed.
Two‐component diacrylate networks from liquid‐crystalline and non‐liquid‐crystalline monomers I. Synthesis of the monomers, phase behaviour of the binary monomer mixtures, network formation
Authors: Braun D. , Alig I. , Junker M. , Walther J.
Published: April 2003

Two‐component networks of diacrylate monomers were synthesized by photoinduced polymerization in the isotropic phase. In all systems one component was a liquid‐crystalline diacrylate, whereas the second component was a non‐liquid‐crystalline diacrylate, which was varied in size, geometry and polarity. The phase behaviour of the monomer mixtures has been analysed by differential scanning calorimetry (DSC). It is influenced by the melting point and the structure of the non‐liquid‐crystalline component. All samples were cross‐linked in the isotropic phase 10°C above the phase transition temperature and a modified differential scanning calorimeter was used to investigate the enthalpies of photopolymerization. The final value and the time dependence of the conversion of acrylate double bonds were calculated from the DSC curves. The final degree of conversion of the acrylate double bonds was between 53 and 71% for all samples, whereas no significant dependence of the degree of conversion on the chemical structure of the monomers or the reaction temperature has been found. In contrast, the time dependence of the conversion was influenced by the chemical structure of the non‐liquid‐crystalline component.
Two‐component diacrylate networks from liquidcrystalline and non‐liquid‐crystalline monomers II. small‐ and wide‐angle x‐ray scattering
Authors: Junker M. , Walther J. , Braun D. , Alig I.
Published: April 2003

The structure of single‐ and two‐component networks of diacrylate monomers which were synthesized by photoinduced polymerization in the isotropic phase has been investigated by small‐ and wide‐angle X‐ray scattering. In all systems one component was a liquid‐crystalline diacrylate whereas the second component was non‐liquid‐crystalline. The chemical structure (size, geometry, and polarity) of the second component was varied. For the single‐component networks the scattering profiles in the small‐angle regime reveal inhomogeneities of the electron density of the order of some ten nanometers. For the two‐component networks no additional scattering contribution due to composition inhomogeneities has been found. This is an evidence that no phase separation occurs during the photoinduced cross‐linking of the thermosets. This picture of an amorphous single‐phase structure is supported by the scattering profiles in the wide‐angle regime. For the single‐component networks a broad maximum is found, the corresponding characteristic length of which can be correlated with the structure of the monomers. For the two‐component networks also only one characteristic length is found which shifts with composition between the length of the single‐component thermosets. By both methods no indication for the development of a liquid‐crystalline phase during network formation has been revealed.
Application of phase transfer catalysis in the synthesis of low‐molecular‐weight epoxy resins
Authors: Pielichowski Jan , Czub Piotr
Published: April 2003

Quaternary ammonium salts, sulfoxides and sulfoianes were used as catalysts in the syntheses of low‐molecular‐weight epoxy resins from bisphenol A and epichlorohydrin. The reaction was carried out in a polar organic solvent at room temperature. The process of synthesis of epoxy resins under phase transfer catalysis (PTC) conditions was studied. Depending on the type of the catalyst and on the reaction conditions epoxy resins with different epoxy group equivalents were obtained. Application of the PTC conditions enabled the synthesis of epoxy resins in a singlestage process, under mild conditions and with a lower amount of epichlorohydrin. It was observed that the system dichloromethane/NaOHaq in the presence of quaternary ammonium salts or sulfoxides or sulfolanes is very convenient in the synthesis of low‐molecular‐weight epoxy resins.
Heterogeneous grafting of maleic anhydride and α‐methylstyrene from atactic polypropylene
Authors: Braun Dietrich , Braun Iris , Krämer Inge , Hellmann Goetz P.
Published: April 2003

Atactic polypropylene (PP) is an amorphous short‐chained by‐product of isotactic polypropylene (iPP). Due to its enhanced solubility, PP is a suited model polymer for kinetic studies of iPP melt reactions. The maleination of PP via radical grafting at high temperatures was investigated. Since maleic anhydride (MAA) produces discoloring oligomers, PP was grafted with a mixture of MAA and α‐methylstyrene (MS). Advantageous is that MS cannot homopolymerize at high temperatures and that MAA and MS tend to copolymerize alternatingly (to colorless products). The kinetics of the grafting process is complicated by a phase separation of PP and [MAA+MS] that is caused by the special attractions between the two monomers. As a result, two grafted PP products are obtained, of which the major is only slightly but the minor is heavily grafted. The latter graft copolymer, which is probably created in the interfaces between phase domains, carries one MAAMS graft per PP back bone chain, approximately with three MAA and five MS units.
Organic‐inorganic hybrid sol‐gel materials, 2. Application for dental composites
Authors: Yang Jen Ming , Chen Hao Sheng , Hsu Ying Gev , Lin Feng Huei , Chang Yen Hsiang
Published: April 2003

By incorporating poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(styrene‐co‐methyl methacrylate) (poly(St‐co‐MMA)) structure units covalently into the SiO2 glass network via a sol‐gel approach, three organic‐inorganic hybrid materials (PMMA‐SiO2, PS—SiO2, and poly(St‐co‐MMA)—SiO2) have been prepared. The three hybrid sol‐gel materials were used as filler (up to 60 wt.‐%) for dental composite resins. The effect of the three filler materials on several mechanical properties of the dental composite resins was investigated. The hardness of the filled dental composites increased with increasing filler content, whereas the bending strength decreased. The compressive strength of the composites was improved, compared with the unfilled resin, but decreased with inreasing filler content.
Mechanical and structural characteristics of phenolphthalein poly(ether sulfone)/ultra‐high molecular weight polyethylene blends
Authors: Huang Dinghai , Yang Yuming , Li Binyao
Published: April 2003

Mechanical and structural properties of blends of phenolphthalein poly(ether sulfone) (PES‐C) with ultra‐high molecular weight polyethylene (UHMWPE) were investigated using tensile and bending testing, scanning electron microscopy and transition electron microscopy. The incorporation of minor amounts of UHMWPE (2 wt.‐%) into PES‐C has a reinforcement effect. With higher concentrations of UHMWPE, the mechanical properties decrease gradually. Structural studies demonstrated that the blends are multiphasic in the whole composition range. The minor UHMWPE, dispersed uniformly and oriented along the flow direction, as well as the strong interfacial adhesion contribute to the increase of the mechanical performance of the blends. The domain size of the UHMWPE phase was found to increase with the increase of its concentration.
Adsorption of BTX compounds from aqueous solutions by water‐insoluble starch
Authors: Chan Wu‐Chung , Yang Shih‐Ping
Published: April 2003

The removal of benzene, toluene and p‐xylene (BTX) compounds from aqueous solutions with highly crosslinked cationic starch containing tertiary amine groups was investigated. The adsorption process has found to be initial pH‐ and initial concentration‐dependent, endothermic, and follows the Langmuir isothermal adsorption.

The heats of adsorption (ΔH) at initial pH = 4 of benzene, toluene and p‐xylene compounds are 29.45 kJ mol−1, 34.41 kJ mol−1, and 35.58 kJ mol−1, respectively, those at initial pH = 10 are 30.17 kJ mol−1, 35.56 kJ mol−1, and 39.39 kJ mol−1, respectively. The order of the amount of adsorbed BTX compounds on the adsorbent is benzene > toluene > p‐xylene.
Studies of copper‐catalysed degradation of epoxy coatings and a method for improving the durability of an epoxy/copper interface after thermal aging
Authors: Gu Xiaohong , Xue Gi
Published: April 2003

It has been demonstrated that an epoxy‐polyamide film is susceptible to be oxidized and degraded on a copper surface at elevated temperature. The amino and amide groups in the epoxy resin are oxidized to nitriles and the polymeric backbone is thermally degraded by the catalysis of copper, resulting a sharp reduction in adhesion between the epoxy resin and copper substrate after aging at 200°C for 30 min. By pretreating the copper surface with polyacrylonitrile, the thermal stability of the coating and the interfacial adhesion can be significantly improved.
Thermogravimetric and ESR studies of polymer/metal precursors for high‐temperature superconductors
Authors: von Lampe Irene , Brückner Angelika , Götze Silke
Published: April 2003

Bi‐Sr‐Ca‐Cu complexes of poly(methacrylic acid) (PMAA) and cresol novolac, which are precursors for high‐temperature superconductors (HTSC) and Cu complexes of those polymers were investigated by ESR spectroscopy and thermogravimetry. In the PMAA samples three different kinds of Cu2+ species were detected: i) Cu2+ pairs, ii) isolated Cu2+ ions and iii) Cu2+ clusters. While Cu2+ pairs are the main species at low Cu concentrations, clusters become dominant at high Cu contents. In the novolac samples Cu2+ was only detected in isolated sites and clusters. The introduction of Cu ions lowered the thermal stability of the polymers and led to a stepwise decomposition. In the PMAA samples the first decomposition step at ≈ 220°C is caused by the Cu2+ pair complexes.
Gelpermeationschromatographie und Kalibrierung an resolischen Phenol‐Formaldehyd‐Kondensaten
Authors: Gobec Georg , Dunky Manfred , Zich Thomas , Lederer Klaus
Published: April 2003

Mehrere Resole mit einem Mengenverhältnis von Formaldehyd zu Phenol von 2,5 bzw. 1,7 und einer Katalysatorzugabe von 8 bzw. 4 Gew.‐% NaOH wurden hergestellt und mit Hilfe der Gelpermeationschromatographie (GPC) untersucht. Dabei erwies sich Tetrahydrofuran mit 0,4 Gew.‐% Trichloressigsäure als geeignetes Lösungs‐ und Elutionsmittel, das auch hochalkalische Resole zu lösen vermag. Diese Harze wurden im niedermolekularen Bereich in bis zu acht einzelne Peaks aufgetrennt, die durch Vergleich mit den Chromatogrammen von Reinsubstanzen, die bei der Resolsynthese als Zwischenprodukte zu erwarten sind, interpretiert wurden. Im höhermolekularen Bereich wurde die Kalibrierung auf der Basis von Polystyrolbzw. Polyethylenglykol‐Standards durchgeführt. Für die hüchstmolekulare Fraktion ergab sich auf Basis der Polystyrol‐Kalibrierung eine Molmasse von ca. 150 kg mol‐1. Die alternative Verwendung eines Brechungsindex‐ und eines UV‐Detektors ergab, daß im niedermolekularen Bereich der UV‐Detektor durch Spuren von Verunreinigungen weniger gestört wird.