bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of reactive diluents on mechanical and physical properties of a UV curable acrylated urethane prepolymer
Authors: Yildiz Emel , Güçlü Hande , Yildirim Hüseyin , Kuyulu Abdülkadir , Güngör Attila 
Published: April 2003

AbstractIn this study, the dependence of the mechanical properties of a UV curable acrylated urethane on reactive diluent types and their amounts was investigated. The acrylated urethane prepolymer was synthesized from isophorone diisocyanate (IPDI), an aliphatic diisocyanate, and polypropylene glycol monomethacrylate (PPGMMA) by stepwise addition reaction. UV sensitive mixtures containing N‐vinylpyrrolidinone (NVP), thiodiethylene glycol diacrylate (TDGDA) and isobornyl acrylate (IBoA) as reactive diluents were irradiated by UV light. An increase in reactive diluent content, either TDGDA or IBoA, caused an increase in tensile strength and a decrease in elongation values. In contrast, above a certain concentration a decrease in tensil strength was observed when NVP was used as reactive diluent.The water absorption capacities of the UV curable acrylated urethane films were observed to depend on type and amount of reactive diluent that was used. Thermooxidative properties of the films were also improved by incorporation of reactive diluents into formulations.
Thermolysis of poly(diaryl diazosulfide)s
Authors: Nuyken Oskar , Lang Armin 
Published: April 2003

AbstractPoly(diaryl diazosulfide)s and model diaryl diazosulfides of the general structure aryl‐NNS‐aryl' are tested for their thermostability. Thermolysis in solution is followed by means of UV spectroscopy. At the beginning of the decay most model diazosulfides follow first‐order kinetics, but show an acceleration of the decay rate in the further course of the thermolysis. In contrast to the models the decomposition of the corresponding polymers cannot be described by first‐order kinetics, except one example (P 1).Thermogravimetry studies show weight losses of 8–12% in the range between 80 and 150°C depending on the structure of the models and polymeric diazosulfides. These values correspond with the content of azo function in these compounds, therefore it is assumed that nitrogen is split off under these reaction conditions.
Studies of polyimide/copper interface and its improvement by a two‐component primer
Authors: Dong Jian , Ji Gending , Xue Gi 
Published: April 2003

AbstractThe inhibition of the imidization of polyamic acid, a precursor of polyimide, in the presence of Cu, was confirmed by the incorporation of Cu2+ ions in polyamic acid films. It was found that the imidization reaction was incomplete below 300°C but decomposition took place when heating above 300°C. Pretreating the Cu surface with a two‐component primer solution containing polybenzimidazole and 2‐mercaptobenzimidazole can make the imidization proceed without retardation and avoid the decomposition above 300°C. By choosing appropriate surface treatment systems, one can achieve the improvement of adhesion between PI and Cu substrate.
Syntheses, morphology and dynamic mechanical properties of AB crosslinked polymers based on vinyl‐terminated polyurethanes/allyl novolac resin
Authors: Chiang Wen‐Yen , Chang Dong‐Meau 
Published: April 2003

AbstractVinyl‐terminated polyurethane (VTPU) was prepared from the PU prepolymer and methacrylamide. The prepolymers were prepared by reacting 4,4′‐diphenylmethane diisocyanate (MDI) with poly(tetramethylene oxide) (PTMO), whose molecular weight is M̄n = 600–700 (this polymer is called VTU1) and M̄n = 1900–2100 (VTU2), respectively. The AB crosslinked polymers (ABCPs) were synthesized from VTPU and allyl novolac resin, synthesized by substituting the hydroxy group of a phenolic resin with the allyl group. For these ABCPs, the phenomena of phase mixing was investigated and confirmed through dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The tensile strength of these ABCPs were improved and accorded with their structures and viscoelastic properties and morphology.
Polarization characteristics of poly(vinyl alcohol) films containing metal iodide
Authors: Yosomiya Takatoshi , Suzuki Yosuke , Yosomiya Ryutoku 
Published: April 2003

AbstractThe polarization properties of iodine complex layer deposited by oxidation of poly(vinyl alcohol) (PVA) containing metal iodide were investigated. Heat‐resistant polarizing films with high polarization efficiency were produced by oxidizing and stretching the PVA containing metal iodide. The results indicate that i) the polarization efficiency of a polarizing film prepared by oxidation of a PVA film containing 1 mmol or more of potassium iodide (KI)/g PVA at 0°C for 120 s in a 10 wt.‐% aqueous solution of H2O2 and a degree of stretching of 400% is high, ii) the heat resistance of the polarizing film in this experiment is higher than that of a filter prepared from a commercial PVA film.
Modified styrene‐diene‐styrene triblock copolymers for oxygen permeation
Authors: Yang Jen‐Ming , Hsiue Ging‐Ho 
Published: April 2003

AbstractThe grafting of vinylpyridine (VP) or 1‐vinylimidazole (VIm) onto styrene‐diene‐styrene triblock copolymer (polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) and polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS)) by radiation‐induced graft copolymerization was studied. The cohesive properties of modified styrene‐diene‐styrene copolymers were calculated according to the group contribution method of Fedors. The changes of properties of modified styrene‐diene‐styrene copolymers reduced the gas permeability of oxygen and nitrogen through copolymer membranes, but increased the O2/N2 selectivity. The morphology of polymeric complexed membranes, which were prepared by complexing (N,N′‐disalicylidene ethylenediamine) cobalt(II) (CoS) with modified SIS and SBS, were studied by means of transmission electron microscopy and optical polarizing microscopy. It was found that the gas permeability was related to the morphological structure of modified styrene‐diene‐styrene block copolymer.
Emulsion polymerization of butyl acrylate induced by sodium lauryl sulfate/hydroxymethane sulfinate
Authors: Wang Cheng Chien , Kuo Jen Feng , Chen Chuh Yung 
Published: April 2003

AbstractHydroxymethane sulfinate (sodium formaldehyde sulfoxylate, SFS) along with sodium lauryl sulfate (SLS) was used to induce the aqueous polymerization of n‐butyl acrylate (n‐BA). The reaction rate, molecular weights and latex stability with those two compounds were found to be promising. However, the polymerization involved a significantly limited conversion and broad dispersity in molecular weights and particle sizes. The polymerization behavior, depending on factors such as the concentrations of SFS, SLS and n‐BA was different from that of traditional emulsion polymerizations. The rate dependence on the reaction temperature was described well by the Arrhenius equation, and the overall activation energy of polymerization thus obtained was 43 kJ/mol, which is close to that of redox‐induced polymerizations.
Synthesis and characterization of low‐viscosity fluoropolyether‐based segmented oligomers
Authors: Scicchitano Massimo , Turri Stefano , Tonelli Claudio 
Published: April 2003

AbstractSix oligomeric polyols having a common perfluoropolyether chain end‐capped by different hydrogenated segments containing hydroxylic groups were synthesized and their properties described. The general scheme for the synthesis of these polyols involved the etherification of the fluoropolyether diol precursor (ZDOL) with epoxides or dibromoalkanes. The former reaction gave directly the polyolic derivatives, while the latter yielded the fluorinated dibromoderivative which could be converted to polyols through the reaction with malonate and final reduction.The viscosity of these oligomers was measured and its dependence on temperature, solvent concentration and hydroxylic end‐groups content was established. The exceptionally low Tg and viscosity together with the good miscibility with common solvents make these polyols very interesting as “resins” suitable for high‐solid coatings.
Increasing of the adhesive properties of poly(propylene) by surface modification
Authors: Novák Igor 
Published: April 2003

AbstractThe applied surface modification methods aim at an increase of the hydrophilicity and the free surface energy (FSE) of isotactic poly(propylene) (iPP).It was shown that for this purpose it is possible to use UV irradiation during 1–2 min, depending on the distance of the source of irradiation from the polymer surface [50, resp. 100 mm]. By the simultaneous effect of phosphorus trichloride (PCl3) and UV irradiation on the polymer surface the FSE was increased by 29% compared to the unmodified polymer and the mechanical work of adhesion was six times the original value. It was found that the application of strong oxidizing agents, such as potassium permanganate (PPM) and ammonium peroxodisulfate (APS), resulted in an increase of the FSE of iPP by 16 to 19%. The efficiency of the modification depends on the time of the modification by aqueous solutions of the oxidizers, as well as on the concentration of the solution. The FSE of iPP modified by UV irradiation does not change with the time after the modification.
Investigation of primers reducing the pink‐ring formation in multilayer printed circuit boards
Authors: Hong S. G. , Wang T. C. , Hong C. M. 
Published: April 2003

AbstractA rapid and easy screening test was applied to assess the capability of various formulated primers to reduce the defect of pink rings in multilayer printed circuit boards. The mixtures of silanes with multifunctional silanol groups (crosslinkers) and 3‐glycidoxypropyl‐trimethoxysilaneSystematic name: 3‐(2,3‐Epoxypropoxy)propyl‐trimethoxysilane.
(referred to as silane C) or N‐(2‐aminoethyl)‐3‐aminopropyl‐trimethoxysilaneSystematic name: 3‐[N‐2‐aminoethyl]aminopropyl‐trimethoxysilane.
(silane B) were proved to be effective in reducing the pink rings. The performance of the mixed silanes using silane A and crosslinkers with aromatic groups were better than other formulated primers which was partly attributed to less amounts of hydrophilic groups and better integrity in the primer films. A developed primer consisting of siloxane compounds had the best performance. The online test confirmed the results from the screening test and demonstrated the feasibility of the designed screening test in assessing the performance of primers. The results of FTIR spectroscopy and thermogravimetric analyses confirmed that the effective primers coated on the copper oxides could improve the curing reaction and the thermal oxidative stability of the epoxy/CuO system.
Preparation and characterization of polymer dispersed liquid crystal films using photosensitive polymers
Authors: Liu Jui‐Hsiang , Chen Ming‐Zeng , Wang Yu‐Fang 
Published: April 2003

Abstract4‐Butyl‐N‐(4‐methoxybenzylidene)aniline (MBBA) and 4‐butyl‐N‐(4‐ethoxybenzylidene)aniline (EBBA) liquid crystals were synthesized. To investigate the applications of hydrophilic monomers and polymers on the field of polymer dispersed liquid crystal (PDLC) films, 2‐hydroxyethyl methacrylate (HEMA) and acrylic acid (Aa) were selected as monomers for the polymer matrix. To prepare the PDLC films, MBBA, EBBA, and commercial liquid crystals ZLI‐2444, 2452, 2459 and BDH‐E7 were mixed with HEMA, Aa and photosensitive materials and then irradiated by UV light. The electrooptical behavior and the microstructure of the PDLC films were investigated by He‐Ne laser and scanning electron microscopy (SEM), respectively. The effects of UV‐light irradiation and monomer ratio on the electrooptical behavior of PDLC films, and the reproducibility and storage stability of the PDLC films were investigated.
Dispersion polymerization of styrene and methyl methacrylate initiated by poly(oxyethylene) macromonomeric azoinitiators
Authors: Yildiz Ufuk , Hazer Baki , Capek Ignác 
Published: April 2003

AbstractMacromonomeric poly(oxyethylene) azoinitiators (macroinimers) MIM‐400 and MIM‐1500 were synthesized and characterized by IR and NMR spectroscopy and DSC techniques. The dispersion polymerizations of styrene and methyl methacrylate (MMA) initiated by poly(oxyethylene) macroinimers (MIM‐400 and MIM‐1500) in water/ethanol were investigated at 60°C. The rate of polymerization was found to increase with increasing concentration of MIM and the increase was more pronounced in the styrene system. In the range of medium conversions the rate of polymerization was found to be proportional to the 1.7th and 1.6th power of [MIM‐400] and [MIM‐1500] for MMA and to the 2.5th power of [MIM‐400] for styrene, respectively.
Grafting fast blue BB onto maleated EPR using reactive extrusion
Authors: Maier Christian , Lambla Morand 
Published: April 2003

AbstractIn order to create a tracer to be used in the determination of residence time distributions, Fast Blue BB dye was grafted onto a maleated ethylene‐propylene rubber (EPRMA). The dye included a phenylamine group, which was reacted with the cyclic anhydride group (CA) on the EPRMA. Reasonably high conversions were obtained in a batch mixer within a short amount of time (less than 10 min). The reaction was then conducted on a co‐rotating self‐wiping twin‐screw extruder, where the dye had to be diluted in 1‐methyl‐2‐pyrrolidone in order to be injected. Although ideal from the point of a carrier medium for the injection and devolatilization, it tended to interfere in the equilibrium relationship between the CA group and its hydrolized form, dicarboxylic acid, and thus in the amidification. Optimizing the screw geometry involved moving the melt seal upstream so that the devolatilization could be performed as soon after the injection as possible.
Differentialkalorimetrische untersuchungen an chloriertem polyethylen und chloriertem polyvinylchlorid
Authors: Hößelbarth Bernd 
Published: April 2003

AbstractDurch Chlorieren in Lösung hergestelltes Polyethylen (PE‐C) zeigt im amorphen Bereich (Chlorgehalt ≥ 30 Gew.‐%) eine kontinuierliche Erhöhung der Glastemperatur Tg mit steigendem Chlorgehalt. Diese Tg‐Chlorgehalt‐Funktion wurde verglichen mit der Tg‐Chlorgehalt‐Funktion des PVC‐C. Es wurde festgestellt, daß die Δcp‐Werte, gemessen bei Tg, in Abhängigkeit vom Chlorgehalt ein Maximum aufweisen, und zwar bei 50 Gew.‐% Chlor für PE‐C und bei 60 Gew.‐% Chlor für PVC‐C.
Synthesis and characterization of copolymers from acrylic and methacrylic acid with 2‐methylaziridine by spontaneous copolymerization
Authors: Rivas B. L. , Pizarro G. del C. , Tagle L. H. , Radic D. 
Published: April 2003

Abstract2‐Methylaziridine (MAz) as a nucleophilic monomer and acrylic acid (AA) and methacrylic acid (MA), respectively, as electrophilic monomers were copolymerized in the absence of initiator at various feed ratios. Copolymers were characterized by elemental analysis, FT‐IR and 1H‐NMR spectroscopy. The monomer reactivity ratios were determined by the Fineman‐Ross and Kelen‐Tüdős methods. Values of r1 and r2 were found to be less than unity for MAz‐AA, and MAz‐MA, corresponding to random copolymers with the tendency to the alternance. For all the copolymers the thermal decomposition with 10% weight loss is higher than 430 K. The reaction order for degradation of all copolymers was zero. The kinetic parameters of the decomposition were determined for all copolymers.
Are microencapsulated antioxidants a feasible technology?
Authors: Billingham N. C. , Garcia‐Trabajo P. 
Published: April 2003

AbstractWe consider the possibility of stabilising a polymer by using a low‐molecular‐weight, mobile and soluble antioxidant, trapped in a small volume fraction of encapsulating material so that it is released into the surrounding polymer to compensate for consumption or loss. Two models are discussed. In the “matrix” model, the additive is dissolved in an encapsulant and its release is controlled entirely by the diffusion coefficient in the encapsulant. In the “balloon” model, the pure additive is surrounded by a wall of encapsulant, through which it permeates into the surrounding polymer. Modelling of the two cases allows the required diffusion or permeation coefficients to be calculated for any chosen loss time. It is found that purely diffusion‐controlled loss would require improbably low diffusion coefficients, whereas the required permeabilities for balloon models are accessible. It is difficult to imagine a system for which the temperature coefficient of loss rate would be low enough to allow elevated temperature processing without loss of the additive.
Search for the sources of color in thermally aged, weathered and γ‐ray irradiated bisphenol a polycarbonate
Authors: Factor Arnold 
Published: April 2003

AbstractBisphenol A polycarbonate (BPA‐PC) is an important high performance engineering thermoplastic well known for its outstanding combination of toughness, transparency and heat resistance. These properties make it an idel material for demanding applications where it is exposed to external stresses such as elevated temperatures, ultraviolet light and γ‐ray sterilization. However, on extended exposure to these conditions, BPA‐PC slowly degrades, turning progressively more yellow, eventually leading to a decrease in its physical properties. Over the years, there has been numerous studies made to understand these degradative processes so as to better design more stable BPA‐PC formulations. In this paper, this chemistry is briefly reviewed along with more recent work in this area with a special emphasis on the efforts made to identifying the actual chemical species responsible for the observed yellow color and the chemistry responsible for their formation.
Heterogeneous photooxidation of solid polymers
Authors: Gardette Jean‐Luc 
Published: April 2003

AbstractPhotooxidation of polymer can undergo heterogeneous effects, a complication which impacts attempts to extrapolate artificial accelerated tests to natural outdoor exposures. The main cause of heterogeneous degradation results from oxygen diffusion‐limited effects. Several experimental techniques can be used to monitor macroscopic heterogeneous oxidation in polymers. These techniques are based on i.r. spectroscopy: micro FTi. r. spectroscopy permits to determine oxidation profiles in polymer materials till a resolution around 10 microns and photoacoustic (PAS) ‐FTi. r. spectroscopy is an interesting method for analyzing the oxidation of the surface layers.
Aspects of stabilization with phosphorous antioxidants in polymers
Authors: Haruna T. 
Published: April 2003

AbstractAs plastics are being used in a variety of applications, demands on a greater level of processing stability are increasing. Phosphites are noteworthy as effective processing stabilizer and the performance of phosphite antioxidants can be correlated to the chemical structure of phosphites. Cyclic phosphite esters derived from 2, 2′ methylene bis‐2, 4‐di‐tert‐butylphenol and some commercially available phosphites were submitted to comparative studies. Decomposition of cumene hydroperoxide, melt flow of polypropylene and consumption of additives after multiple extrusions were investigated to understand the activity of phosphites as process stabilizers in polypropylene.This study suggests that phosphites play an important role in process stabilization when used in combination with sterically hindered phenols, and that the activity of phosphites may be predicted by their reactivity on hydroperoxide.
Pyrolysis with respect to recycling of polymer
Authors: Kaminsky W. 
Published: April 2003

AbstractMost plastics are produced from oil and have a high potential as hydrocarbon sources for the chemical industry. Pyrolysis is a practicable way to pyrolyze mixed plastics. The fluidized bed pyrolysis has turned out to be particularly advantageous. 25 to 45 percent of product gas with a high heating value and 30 to 50 percent of an oil rich in aromatics, could be recovered. The oil is comparable to that of a mixture of light benzene and bituminous coal tar. Up to 60 percent of ethene and propene are produced by using mixed polyolefins as feedstock. Under appropriate conditions the pyrolysis could be successful on the market.
Degradative extrusion as a pretreating process for chemical recycling of plastics waste
Authors: Michaeli W. , Lackner V. 
Published: April 2003

AbstractChemical conversion processes can also be used for the recycling of plastics waste. The plastics, however, must be adapted to chemical recycling processes by liquefaction and dehalogenation. A reprocessing method for plastics waste has been developed, which pretreats these waste fractions by degradative extrusion. The polymers are cracked in an extruder under the influence of thermal and mechanical energy and with the introduction of degradation‐promoting additives. Decomposition products such as halogens are eliminated and recovered in a defined manner through degassing and also a sufficient reduction of the melt viscosity was carried out by molecular degradation.
Recycling and restabilization of polymers for high quality applications. An Overview
Authors: Pfaendner R. , Herbst H. , Hoffmann K. , Sitek F. 
Published: April 2003

AbstractMechanical recycling of thermoplastics for high value applications is directly associated with restabilization. The state of the art of processing‐, long term heat‐ and light stabilization of recyclates in different polymers (e.g. PP, PP/EPDM, HDPE, LDPE, PS, PVC and various blends) with examples from packaging, distribution, automotive and construction industry is shown. Because of predamage and impurities, recyclates degrade faster and differently compared with virgin polymers and, therefore, specially designed stabilizer systems are required according to the previous damage, subsequent application and type of polymer. Recommendations for restabilization include combinations of phenolic antioxidants and phosphites as well as HALS compounds or “Recyclostab” stabilizer systems.
Photodegradation of UV absorbers: Kinetics and structural effects
Authors: Pickett James E. , Moore James E. 
Published: April 2003

AbstractWhen poly(methyl methacrylate) films containing UV absorbers are exposed to UV light, the absorbers undergo photodegradation resulting in loss of absorbance. If the data extend for less than one half‐life, both zero and first order kinetic treatment give fairly linear fits, but the rate constants so derived are dependent on the initial absorbance of the films. When the zero order rate constants are corrected to account for the higher rate of degradation near the surface compared with the bulk that occurs in highly absorbing films, consistent “infinite absorption” zero order rate constants are derived. The inhomogeneous degradation is due to only the highly absorbed, higher energy light contributing significantly to the degradation. For the benzophenone and benzotriazole classes of absorber, at least 65% of the degradation is due to light with wavelengths < 350 nm. Structural variations generally caused only small differences in the rates of degradation of these classes of absorbers unless the substitutions disrupted the intramolecular hydrogen bonds that are critical for stability. If the hydrogen bond is weakened, the absorber is less stable.