摘要:

AbstractAir plasma treatment has been used to introduce polar functional groups onto polypropylene surfaces to enhance the adhesion of coatings and paints. Plasma exposure times as well as the reaction medium (ambient, technical, and moistured technical air) have been varied. Time‐dependent changes subsequent to the plasma treatment are monitored by contact‐angle measurements. After short plasma exposures, the polar component of the surface energy is observed to decrease, to reach a minimum after ≈ 40 min. This behavior is interpreted in terms of a rotation of the introduced surface hydroperoxide groups into the interior of the polymer. This undesired loss in surface functionalization can be avoided by (a) increasing the treatment time in dry air, (b) use of moistured air as the reaction medium, or (c) posttreatment of the plasma‐treated parts by water immersion. A plasma exposure of 120 s in dry air, followed by posttreatment in an aqueous medium at room temperature for 2–5 min, results in reproducible values of the surface energy σ, with polarities (σpolar/σtotal) close to the desired value of ≈ 50%. © 1993 John

ISSN:0021-8995    

DOI:10.1002/app.1993.070500201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe influence of temperature variation on the kinetics and the polymer properties in the homo‐ and copolymerization of ethylene in a solution reactor is discussed. The Polymerization is conducted in a semibatch mode at 320 Psig total reactor pressure for 10 min polymerization time. Temperature variations in the range 145–200°C in both home‐and copolymerization of ethylene with 1‐octene shows that the highest catalyst yield was obtained at temperature of 165–175°C. At the optimal temperature, a high initial maximum in the rate of ethylene consumption is attained in a few seconds followed by a relatively slow decay when compared with polymerization conducted at higher temperatures. Polymerization at temperatures ≥ 185°C resulted in a lower peak in the consumption rate of ethylene accompanied by a rapid decay with time. In the case of ethylene/1‐Octene copolymerization, a rather low comonomer incorporation level is obtained at the conditions employed; the 1‐octene incorporated was only 0.2–0.7 mol %. HigherMwvalues, of about 350,000 at 145°C, are obtained in homopolymerization in comparison toMwvalues obtained in copolymerization, of about 195,000 at the same temperature. Over the temperature range of 145–200°C, bothMwandMnvalues vary by about 40%. ©

ISSN:0021-8995    

DOI:10.1002/app.1993.070500202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe high‐temperature solution homopolymerization of ethylene and copolymerization with 1‐hexene using highly active TiCl4/MgCl2‐supported catalyst was studied. Experiments with pressure variations in the range 100–400 Psig were carried out at 185°C and for 10 min polymerization time. Both peak initial rate of polymerization and the catalyst productivity in homo‐ and copolymerization were found to increase steadily with increasing reactor pressure. Higher polymerization rates arose in copolymerization compared to homopolymerization, especially above 200 Psig total pressure. In both cases, the reaction order with respect to ethylene concentration was close to two. The number‐average molecular weight was found to be almost independent of pressure, whereas in copolymerization, the weight‐average molecular weight was observed to decrease from about 200,000 to 120,000 over the range of pressure studied. The polydispersity index in copolymerization was found to decrease steadily from 8 to about 4 with increasing pressure. © 1993 John

ISSN:0021-8995    

DOI:10.1002/app.1993.070500203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn ethylene vinyl alcohal copolymer was functionalized withm‐isopropenyl‐α,α‐dimethyl benzyl isocyanate using reactive processing in a mixer. The Functionalization introduces pendant unsaturation to the polymer, which allows radiation cross‐linking to gel contents>70% at radiation doses below 100 kGy. Unfunctionalized ethylene vinyl alcohal copolymer, on the other hand, forms no gel upon irradiation. The functionalization was completed within a few minutes of reactive mixing, which was confirmed with both FTIR and13C‐NMR measurments.The oxygen permeability of ethylene vinyl alcohal copolymer increased with increasing degree of functionalization, and irradiation of the samples formed trapped radicals, which act as oxygen scavengers. Consequently no oxygen permeability was detected. However, radical activity was inhibited by annealing the samples at 110°C resulting in a 24% higher oxygen permeability values of the irradiated unfunctionalized samples were approximately 13% lower.Laminates ofm‐isopropenyl‐α,α‐dimethyl benzyl isocyanate functionalized ethylene vinyl alcohal copolymer andm‐isopropenyl‐α,α‐dimethyl benzyl isocyanate functionalized ethylene vinyl hydroxyethyl methacrylate copolymer acquired improved adhesive strength both at dry and wet conditions as well as at elevated temperatures upon exposure to radiation.

ISSN:0021-8995    

DOI:10.1002/app.1993.070500204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAn aqueous‐base developable photoresist based on photoinduced cationic polymerization has been prepared by copolymerization of glycidyl methacrylate (GMA) and methacrylic acid (MAA). The copolymer containing 83 mol% of GMA unit is soluble in an aqueous base and crosslinked in the presence of photogenerated acid caused by acid‐initiated ring‐opening polymerization of pendant epoxide groups. Exposure results in the generation of acid and the subsequent baking process promotes the diffusion of photogenerated acid, which initiates the cationic crosslinking of the epoxide rings. It was also found that the sensitivity of the copolymer was remarkably enhanced when a divinyl ether monomer is added as a bifunctional crosslinker. The sensitivity enhancement may be caused by the high reactivity of the divinyl ether monomer in the presence of acid. The resist comprised of the copolymer, the vinyl ether monomer, and diphenyliodonium 9,10‐dimethoxy‐an‐thracene‐2‐sulfonate as photoacid generator exhibited the sensitivity of 20 mJ/cm2. A good pattern profile with high resolution was attained by exposure to a 365 nm light followed by a postexposure bake at 60°C for 3 min. © 1993 Joh

ISSN:0021-8995    

DOI:10.1002/app.1993.070500205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPhase diagrams including tie lines for three ternary solvent‐polymer‐polymer systems consisting of tetrahydrofuran‐polystyrene‐polytetrahydrofuran at 30°C have been obtained using size exclusion chromatography. The effect of molecular weight on polymer‐polymer compatibility has been investigated. A liquid‐liquid equilibria (LLE) database has been used to compare UNIQUAC and a modified Flory‐Huggins model with respect to their ability to correlate LLE data. Both models contain six adjustable parameters. As previously observed in the literature, the estimation of the UNIQUAC parameters is troublesome due to the model's complexity and the intercorrelation of the parameters. On the basis of better performance and ease of use, the Flory‐Huggins model is recommended. The Flory‐Huggins model is capable of accurately describing LLE of systems which exhibit quite complex tie line behavior. © 1993 J

ISSN:0021-8995    

DOI:10.1002/app.1993.070500206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe polyester and diimide–diacid‐modified polyester prepolymer have been synthesized with different molecular weights through melt polycondensation of 1, 6‐hexanediol (HD), trimethylol propane (TMP), isophthalic acid (IPA), diimide diacid, and phthalic anhydride (PA) at various molar ratios. The prepolymers were then mixed with an equivalent phenol‐blocked TDI and /or HMDI inm‐cresol in deriving the polyester urethane varnishes. The degree of crosslinkage and thermal behavior have been investigated here. © 1993 John Wiley

ISSN:0021-8995    

DOI:10.1002/app.1993.070500207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSulfonated aromatic polyamide and different salts were synthesized. Water vapor diffusion in these polymers and X‐ray diffraction of these polymers before and after water immersion were studied. The concentration dependence of the diffusivity is related to the morphological structure in the dry state and the change induced by absorbed water. © 1993 John Wiley&Sons, I

ISSN:0021-8995    

DOI:10.1002/app.1993.070500208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites have been studied. The experiment results show: the crosslink density is an important factor that influences the loss factor of polyether urethane damping materials; increasing the amount of pendant methyl of the backbone contributes to raising the value of the loss factor (tan δ) and broadens the damping temperature range; adding the planar filler can increase the shear motion and the internal dissipation in polyurethane materials. As the thickness ratio and the Young's modulus of the constraining layer increase, the composite loss factor (η) increases significantly. © 1993 John Wiley&Sons, I

ISSN:0021-8995    

DOI:10.1002/app.1993.070500209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAdsorption of polymer on filler from bulk is known to result in a partial loss of polymer solubility (“bound rubber”). The existing theories of this phenomenon were critically examined, and the random adsorption model suggested by the author was found to provide the most complete explanation of available experimental data. Theory based on this model and containing one adjustable parameter (filler surface area per adsorption site) correctly predicts the change of molar mass distribution with adsorption on filler and satisfactorily describes the experimental dependence of fraction B of the filler‐bound polymer on filler concentration and surface area and onMwof the polymer, in both narrow and very broad molar mass distributions. No distinct effect onBof a moderate degree of branching of EPM, EPDM chains could be detected. It is concluded that the modification of the random adsorption model suggested by Shiga is not warranted, neither theoretically nor experimentally. © 1993 John Wiley&Son

ISSN:0021-8995    

DOI:10.1002/app.1993.070500210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY