摘要:

AbstractRheological properties of two polyesters; poly(ethylene terephthalate) (PET) and bisphenol A‐50/50 isophthalic/terephthalic acid based polyarylate (PAR), and their 85/15, 50/50, and 30/70 (PET/PAR) blends were investigated using a RDS rheometer, 290–310°C. Measurements included complex viscosity and modulus. Activation energy for flow and relaxation spectrum were subsequently calculated. Results indicated that PET/PAR blends are rheologically incompatible, i.e., zero‐shear viscosities of the blends showed a negative deviation from the averages of the two homopolymers with a sharp minimum at 85/15 composition. The relaxation spectrum for 85/15 blend also showed a relaxation plateau, a characteristic of rigid particle suspension. The morphology of the polymer blends was examined from cryogenically fractured and etched surface using a scanning electron microscopy (SEM). Morphological observation indicated that PAR‐rich phases, order of 0.1μm, were finely dispersed in PET phase for 85/15 blend, whereas the dispersion of PET phase in PAR‐rich phase was in spherical form, order of 0.5μm in diameter, for the

ISSN:0021-8995    

DOI:10.1002/app.1990.070401101

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

年代:1990

数据来源: WILEY

摘要:

AbstractPolyurethane films were prepared by solution casting using a three‐component system consisting of polymeric MDI, a propylene oxide‐based polyether triol and kraft lignin fractions of different molecular weights. The polyether triol was used as soft segment. The composition of the polyurethanes was varied whereas the NCO/OH ratio was kept constant. The crosslink density increased with increasing molecular weight of the kraft lignin fraction used, which is a result of an increase in functionality of the kraft lignin with increasing molecular weight. Polyurethanes prepared from low molecular weight kraft lignin were found to be more flexible than those prepared from medium and high molecular weight kraft lignin (at lignin contents below 30%). At kraft lignin contents higher than about 30% (which at the NCO/OH ratio used corresponds to a hard segment content of about 70%), rigid and glassy polyurethanes were obtained regardless of the molecular weight of the kraft lignin fraction u

ISSN:0021-8995    

DOI:10.1002/app.1990.070401102

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

年代:1990

数据来源: WILEY

摘要:

AbstractFlow behaviour of melt‐mixed blends of crosslinkable polyethylene (XLPE) and silicone elastomer with and without vinyl silane are studied over the entire composition range. Viscosity and extrudate swelling have been studied as a function of shear rate and processing temperature. The effect of shearing and temperature have pronounced effect as is observed from the data of shear modulus, stored elastic energy, relaxation time, etc. Extrudate surface morphology is studied by scanning electron microscopy. A structure consisting of cross‐linked microgelled silicone elastomer dispersed in continuous XLPE matrix is propo

ISSN:0021-8995    

DOI:10.1002/app.1990.070401103

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe mechanism that describes the thickening process of unsaturated polyester resins with inorganic oxides and hydroxides is presented. This mechanism includes the formation of water, the formation of the ion cluster, the network expansion and the equilibrium, where the viscosity reaches a constant value.

ISSN:0021-8995    

DOI:10.1002/app.1990.070401104

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

年代:1990

数据来源: WILEY

摘要:

AbstractPolymide (PI) resins which are produced by an in situ imidization condensation reaction of polyamic acid (PAA) precursors were evaluated for use as binders in high‐temperature performance lightweight cement‐filled material systems. Unfortuanately, the presence of partially hydrated cement in the system led to strength retrogression at room temperature. Significant mechanical failure was observed upon exposure of the specimens to steam at>150°C. This was found to be due mainly to alkali catalyzed hydrolysis of the functionaries of unreacted PAA adjacent to the cement surfaces and the imide rings of PI matrices. The formation of Ca‐complexed carboxylate salts derived from the hydrolysis resulted in chain scission of the polymer, thereby decreasing the mechanical strength, and making the composites unsuitable for use in aqueous enviro

ISSN:0021-8995    

DOI:10.1002/app.1990.070401105

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of this study is to determine if the chemical coposition of post dodecyl benzene (PDB) which is obtained as the by product during the production of dodecyl benzene (DDB) at PETKIM, Petrochemical Corporation, is a suitable raw material for the production of alkyl benzene sulphonic acids of high molecular weights. In this work, physical and chemical properties of PDB are determined and results are compared with literature values. Chemical composition analysis are done by IR spectroscopy. Thus, the types of alkylates in PDB are determined both qualitatively and quantitatively, the results showed that PDB consist mainly of mono‐and m‐di‐alkyl benzenes, only a small amount of p‐di‐alkyl benzenes are als

ISSN:0021-8995    

DOI:10.1002/app.1990.070401106

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

年代:1990

数据来源: WILEY

摘要:

AbstractBisphenol‐A polycarbonate (PC) and polystyrene (PS) were melt‐blended and molded for dynamic mechanical tests on a Dynastat. Corresponding powders were submitted to thermal analysis using the differential scanning calorimeter. The deduced glass transition temperatures of the blends and those of the pure polymers were compared to estimate the miscibility of the two polym

ISSN:0021-8995    

DOI:10.1002/app.1990.070401107

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

年代:1990

数据来源: WILEY

摘要:

AbstractBisphenol‐A polycarbonate and an aromatic linear copolyester were melt blended for dynamic mechanical tests using a Dynastat. Corresponding powders were used in thermal analysis by differential scanning calorimetry. The deduced glass transition temperatures of the pure polymers and blends were compared to estimate the miscibility of the two polymer

ISSN:0021-8995    

DOI:10.1002/app.1990.070401108

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of a remote nitrogen plasma on polyethylene and polystyrene was studied. The gas flow rate, the dilution of reactant gas, exposure times, and reactor base pressure were all found to have a large impact on the efficiency of nitrogen incorporation. Optimum conditions caused 18 atom % nitrogen to be incorporated within 20 seconds for polyethylene and 10 seconds for polystyrene. Studying a remote nitrogen plasma treated polyethylene sample over a period of 1 month indicated that except for a drop in the % N on initial exposure to air the concentration of nitrogen on the surface remained steady within the experimental limits. Angle resolved photoelectron spectroscopy indicated that nitrogen is incorporated to a depth below the analysis depth of XPS.

ISSN:0021-8995    

DOI:10.1002/app.1990.070401109

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

年代:1990

数据来源: WILEY

摘要:

AbstractSurface properties of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their poly(methyl methacrylate) (PMMA) blends have been intensively studied to draw a relationship between surface segregation behavior and adhesion performance. The fluoroalkylsilicone—PMMA block copolymers containing thre kinds of fluoroalkyl side chains (i.e., 3,3,3‐trifluoropropyl) (CF3CH2CH2−, abbreviated as TFP), tridecafluoro‐1,1,2,2‐tetrahydrooctyl [F3C(CF2)5CH2CH2−, TFO], and heptadecafluoro‐1,1,2,2‐tetrahydrodecyl groups [F3C(CF2)7CH2CH2−, HFD] on the siloxane chains were prepared according to the macroazoinitiator method. Contact angle measurement and X‐ray photoelectron spectroscopy (or ESCA) were used to obtain structural information on the surface of the solution‐cast films. A significant effect of fluroalkyl groups on the surface accumulation not only in silicon but also fluorine atoms were observed for relatively long fluoroalkyl side chains (i.e., TFO and HFD). On the contrary, TFP group was found to be effective to orient to the hydrophilic surfaces (i.e. glass‐side surfaces). The surface accumulation of fluoroalkyl groups in the films was also reflected by the 180° peel strength against pressure‐sensitive adhesives as a measure of the adhesion performance. These results indicated that incorporation of relatively long fluoroalkyl groups much enchanced the surface hydrophobicity (and/or oleophobicity) of solution‐cast films in addition to that of the siloxane‐enriched surfaces. The composition and orientation of the functional groups on the surface were al

ISSN:0021-8995    

DOI:10.1002/app.1990.070401110

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

年代:1990

数据来源: WILEY