bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of nylon‐6 with wholly rigid poly(m‐phenylene isophthalamide)
Authors: Wang Huei‐Hsiung , Lin Ming‐Fung
Published: April 2003

In this study, the flexible nylon‐6 was reinforced by the wholly rigid aromatic polyamide poly(m‐phenylene isophthalamide) (PmIA) (Nomex) by physical polyblending and chemical copolymerization using p‐aminophenylacetic acid (P‐APA) as a coupling agent. From DSC measurements, it was shown that Tg of the polyblends increased with the increase of Nomex content. The Tg and Tm of multiblock copolyamides were found to be higher than those of polyblends and triblock copolyamides. Scanning electron microscopy revealed that the polyblends were a dispersed phase structure, although the multiblock copolyamides exhibited a homogeneous texture rather than an aggregated one. From the wide‐angle X‐ray diffraction pattern, it was found that the triblock copolyamides and polyblends had two diffraction peaks, i.e., 2 θ = 20.5 and 24°. However, the multiblock had only one at 2 θ = 20°, indicating a different crystal structure for multiblock copolyamides. For the mechanical properties, it was found that the multiblock copolyamides had a more significant reinforcing effect than those of polyblends and triblock copolyamides.
Rubber‐Modified epoxies. IV. Influence of morphology on mechanical properties
Authors: Verchere D. , Pascault J. P. , Sautereau H. , Moschiar S. M. , Riccardi C. C. , Williams R. J. J.
Published: April 2003

The mechanical properties of a system consisting of a bisphenol A diglycidylether (DGEBA) expoxy, cured with a cycloaliphatic diamine (4,4′‐diamino‐3,3 dimethyldicyclohexyl‐methane, 3DCM), in the presence of an epoxy‐terminated butadiene‐acrylonitrile random copolymer (ETBN), was studied as a function of the cure schedule and the initial rubber concentration. Fracture toughness (KIc) and fracture energy (GIc) were increased, while Young's modulus and yield strength decreased slightly with increasing volume fraction of the dispersed phase. We show that there is no significant influence of the precure schedule and of the various observed particle diameters on the mechanical properties for a constant rubber volume fraction. In our case, the main deformation process in the rubber‐modified epoxy networks is shear yielding while cavitation is negligible.
Polybutylene terephthalate/high‐density polyethylene alloys. I. Morphological studies
Authors: Joshi M. , Misra A. , Maiti S. N.
Published: April 2003

Polybutylene terephthalate (PBT) is a commercially successful thermoplastic polyester but has certain drawbacks such as low impact strength and low melt strength. An attempt has been made to modify the properties of PBT by blending it with polyolefin such as highdensity polyethylene (HDPE). Since PBT and HDPE are incompatible, an ionomer has been used as a compatibilizer to form an alloy. Alloys of PBT and HDPE with varying amounts (2‐8%) of ionomer were prepared by melt blending. The ultimate mechanical properties improved significantly on the addition of the ionomer due to an increase in interfacial adhesion between PBT and HDPE. DSC studies show that the presence of ionomer facilitated the crystallization of PBT in the alloy. DMTA studies show that more of PBT (amorphous) is going in to the HDPE‐rich phase in the presence of ionomer. The morphology of the alloys was studied using scanning electron microscopy (SEM), polarizing microscopy (PM), and small‐angle light scattering (SALS). They showed improved dispersion of HDPE domains in PBT matrix with increasing ionomer content and change in the type of superstructure on adding the ionomer. It has been shown that an alloy of PBT and HDPE with improved mechanical properties and homogeneous morphology can be made with use of ionomer as a compatibilizer. Such alloys are cost effective and can find use in several engineering applications.
The effect of blending temperature, composition, and shear rate on PET/Vectra A900 LCP blend viscosity and morphology
Authors: Perkins W. G. , Marcelli A. M. , Frerking H. W.
Published: April 2003

The rheological and morphological properties of several melt‐blended compositions of poly(ethylene terephthalate) (PET) and Vectra A900 liquid crystalline polyester were investigated, using blending temperature, composition, and shear rate as variables. Rheological behavior was determined at several shear rates on an Instron capillary rheometer at 300°C, and three‐dimensional surface plots of the results were prepared, detailing the effect on melt viscosity of changes in the variables. Scanning electron microscopy was used to examine the internal morphology of selected samples. In the preparation of melt blends containing an isotropic and anisotropic polymer, blending temperature and composition both influence the resulting morphology. These effects are accentuated during extrusion of the blends at low shear rates and diminished at high shear rates.
A self‐vulcanizable and miscible blend system based on hypalon and carboxylated nitrile rubber
Authors: Mukhopadhyay Sujata , De P. P. , De S. K.
Published: April 2003

Blends of hypalon and carboxylated nitrile rubber can be vulcanized during molding at high temperatures without addition of any curing agent. This is supported by studies on a Monsanto rheometer, solvent swelling, and FTIR spectroscopy. We designate such a blend system as “self‐vulcanizable rubber blend.” Dynamic mechanical analyses and differential scanning calorimeter studies show that hypalon and carboxylated nitrile rubber form a completely miscible blend. Physical properties of the blends are comparable to that of control single‐rubber vulcanizates. The blend can be reinforced by carbon black filler.
Reactive melt blends of nylon with poly(styrene‐co‐maleic anhydride)
Authors: Kim Byung Kyu , Park Sang Jin
Published: April 2003

Melt blends of nylon with poly(styrene‐co‐maleic anhydride) (SMA) were prepared in a twin‐screw extruder. Viscoelastic properties of the melt and morphological, thermal, and mechanical properties of the blends were determined. Fourier‐transform infrared (FTIR) spectroscopy measurement indicated reactions between nylon and SMA. Melting peak temperature (Tm) of nylon was not changed in blends. This, together with the FTIR results, assured that the reactions occur mainly with the free amide end groups of nylon. Melt viscosity, elasticity, and the heat‐distortion temperature (HDT) of nylon was significantly increased with the addition of SMA. Tensile strength and impact strength of nylon were, respectively, in general, increased and decreased with SMA.
Analysis of oxidized moiety of partially periodate‐oxidized cellulose by NMR spectroscopy
Authors: Maekawa Eiichi
Published: April 2003

Periodate‐oxidized celluloses (S‐100, S‐70, S‐50) with different degrees of oxidation were prepared. It is presented in this article that oxidized moieties of partially periodate‐oxidized cellulose are determined from analyses of 1H and 13C nuclear magnetic resonance (NMR) spectra of those reduction products and the corresponding polytriacetates.
Miscibility of poly(tetrahydrofurfuryl methacrylate) and poly(tetrahydropyranyl‐2‐methacrylate) with some chlorine‐containing polymers
Authors: Chong Y. F. , Goh S. H.
Published: April 2003

The miscibility of poly(tetrahydrofurfuryl methacrylate) (PTHFMA) and poly(tetrahydropyranyl‐2‐methacrylate) (PTHPMA) with some chlorine‐containing polymers was studied by differential scanning calorimetry (DSC). PTHPMA was found to be miscible with poly(vinyl chloride) (PVC), polyepichlorohydrin (PECH), and a vinylidene chloride/vinyl chloride copolymer [P (VDC/VC)] and only partially miscible with an epichlorohydrin/ethylene oxide copolymer [P (ECH/EO)]. PTHFMA was shown to be miscible with PECH and P(VDC/VC), but its miscibility with P(ECH/EO) is composition‐dependent. Information about interactions between components in PTHFMA/P (VDC/VC) and PTHPMA/P(VDC/VC) blends was estimated from melting‐point depression. The interaction parameters B were found to be −1.7 and −3.6 J/cm3 for PTHFMA/P(VDC/VC) and PTHPMA/P(VDC/VC) blend systems, respectively. The miscibility behavior of PTHFMA and PTHPMA is compared to that of poly(cyclohexyl methacrylate).
Glass fiber reinforced polypropylene/EPDM blends. II. Mechanical properties and morphology
Authors: Gupta A. K. , Srinivasan K. R. , Kumar P. Krishna
Published: April 2003

Tensile and impact properties of the ternary system polypropylene (PP)/ethylene propylene diene elastomer (EPDM)/glass fiber (GF) and the corresponding binary systems PP/EPDM blend and PP/GF composite are studied. Results are presented and analyzed as functions of compositional variables, viz., (i) matrix PP/EPDM blending ratio at constant GF loadings and (ii) GF loading at constant matrix blending ratios for the ternary system and (iii) EPDM content for PP/EPDM binary system and (iv) GF content for the binary system PP/GF, respectively. The role of individual components EPDM and GF in these mechanical properties is discussed and their combined effects are inspected at certain composition ranges. Theoretical analysis of tensile data is presented which reveals the effect of EPDM on the reinforcing effect of GF. Unlike the conventional role of an elastomer, increase of EPDM content in the presence of GF increases the modulus of the ternary system. Impact strength of the ternary system increases with increasing GF content both in the presence and absence of EPDM, showing a distinct minimum at matrix blending ratio PP/EPDM 90/10. Scanning electron micrographs of impact‐fractured surfaces are presented to illustrate the dispersion of the two phases of the polyblend matrix, fiber alignment, and the fiber interface.
Interpenetrating polymer networks from polyurethanes and poly(methyl acrylate)
Authors: Frisch Harry L. , Wang Linfu , Huang Weiyu , Hua Yao He , Xiao Han X. , Frisch Kurt C.
Published: April 2003

Simultaneous two‐component interpenetrating polymer networks (IPNs) of polyurethane (PU)–poly(methyl acrylate) (PMA) were prepared, as well as the corresponding pseudo‐IPNs. A comparison was made between the full IPNs, pseudo‐IPNs, and the respective homopolymers. Their ultimate mechanical properties were obtained and the dynamic glass transition temperatures (Tg's) were found using a thermomechanical analyzer. At all compositions, a single Tg(except 50–50 wt %) was found.
Polyurethane–polystyrene interpenetrating polymer networks synthesized at low temperature: Effect of crosslinking level
Authors: Lee Doo Sung , Park Tae Sung
Published: April 2003

Interpenetrating polymer networks (IPNs) of polyurethane (PU)–polystyrene (PS) containing 50 wt % PU were synthesized at low temperature with varying crosslink density of each component. PU was polymerized first, followed by the photopolymerization of PS at low temperature (0 and 40°C). The theoretical molecular weight between crosslink (M̄c) of PU ranged from 8200 to 2050, and the M̄c of PS varied from linear to 2000. The degree of mixing of the components in these IPNs was investigated using dynamic mechanical analysis, electron microscopy, and density measurement. The degree of mixing increased with decreasing M̄c and/or synthesis temperature. The crosslink density variation at low synthesis temperature is more effective in enhancing the miscibility of IPN than at high synthesis temperature, because both the temperature and crosslink density can affect the polymer chain mobility during the synthesis. The variation of PU network crosslink density shows the better effect in increasing the miscibility of IPN than that of the PS network. The morphology and the density behavior agree well with the dynamic mechanical result.
Polysulfones and their derivatives: Materials for membranes for different separation operations
Authors: Staude Eberhard , Breitbach Ludger
Published: April 2003

Polysulfones, as well as their derivatives obtained by chemical reactions, are versatile materials for membrane preparation. The selection of an optimum material clearly depends on the separation process for which the membranes will be used. Membranes made from these materials may serve diverse functions, ranging from an actual permselective separation barrier to a support for a thin membrane layer in a composite structure. Illustrative examples of polysulfone membranes useful in these various applications are given and compared with respect to their cross‐sectional and/or their surface morphology as well as in their surface charge and chemical composition.
Effect of comonomer composition on the properties of polyacrylonitrile precursor and resulting carbon fiber
Authors: Tsai Jin‐Shy , Lin Chung‐Hua
Published: April 2003

Since the itaconic acid (IA) comonomer is the potential initiator of cyclization, therefore the introduction of IA comonomer into polyacrylonitrile (PAN) precursor can depress the onset of exotherm (or cyclized temperature) and peak temperature. However, the more the IA content, the lower the conversion of acrylonitrile (AN) in the polymerization reaction. Although 2‐ethylhexyl acrylate (2‐EHA) comonomer in PAN precursor may prevent the cyclization propagation of nitrile groups during oxidation, PAN precursor with a few percent of 2‐EHA comonomer has a more preferred orientation. As the content of 2‐EHA comonomer further increases, the orientation of the resulting carbon fiber decreases correspondingly.

In this study, PAN precursor, with the composition of 98 mol % AN, 1.5 mol % 2‐EHA, and 0.5 mol % IA, and its resulting carbon fiber have the best mechanical properties. From the results, it is shown that there is a good relationship between the tenacity and modulus of PAN precursor and those of its resulting carbon fiber.
Simple model for swelling‐induced stresses in a supported polymer thin film
Authors: Fu T. Z. , Durning C. J. , Tong H. M.
Published: April 2003

Solvent transport in multilayer thin film structures can induce damaging stresses. It is important to understand these quantitatively for the design of processing methods for microelectronics manufacture. As a model for such systems, this article focuses on the connection between solvent transport in a thin, supported film and the induced bending curvature of the film/substrate combination. We develop a simple mechanical model to calculate the bending curvature based on the transport‐induced stresses. A phenomenological moving boundary description of non‐Fickian solvent transport often found in glassy polymers has been used. The evaluation of dimensionless bending curvature for a number of generic cases is presented. As an application of the model, experimental data for a polymide (PI)/quartz‐n‐methyl‐2‐pyrrolidinone (NMP) system involving significant swelling (15–20%) of the PI film is analyzed. The analysis shows that the measured bending during the transport of NMP in the PI film compares well with that predicted based on an “intermediate,” non‐Fickian diffusion mechanism of NMP, consistent with the finding obtained from a laser interferometric study. Estimation of the swelling‐induced stress shows that it is large and as significant as that due to thermal “curing.”
Morphological deformities in cotton
Authors: Patel G. S. , Iyer K. R. Krishna
Published: April 2003

Eight types of structural deformities have been identified in cotton fibers by using the SEM, and their incidence has been quantified in four varieties grown in India. Although the total number of deformities per cm was found to be nearly equal in these four varieties, their number showed a wide spread when structural reversals (which constitute one class of deformity) were excluded. The correspondence found between the number of defects other than reversals and the drop in bundle tenacity with increase in gauge length seems to suggest that weak links other than reversals might strongly influence fiber strength.
Curing of diepoxides with tertiary amines: Influence of temperature and initiator concentration on polymerization rate and glass transition temperature
Authors: Vazquez A. , Bentaleb D. , Williams R. J. J.
Published: April 2003

The cure of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA), with benzyldimethylamine (BDMA), was investigated using differential scanning calorimetry. The kinetics showed a first‐order behavior with respect to both epoxy and tertiary amine concentrations and a non‐Arrhenius dependence on temperature. An activation energy could be defined only in the low‐temperature range, i.e., from 80 to 120°C. Its value (E = 24.2 kJ/mol = 5.8 kcal/mol) indicates a very slight dependence on temperature. The glass transition temperature of epoxy networks decreased with an increase in both the tertiary amine concentration and the cure temperature. These effects are attributed to plastification by the free amine and to the decrease in the average length of polyether chains, which, in turn, increases the number of network defects.
Synthesis of a polyacrylamide chelating resin and applications in metal ion extractions
Authors: Latha A. Gomathy , George Benny K. , Kannan K. G. , Ninan K. N.
Published: April 2003

A series of differently crosslinked polyacrylamide chelating resins were prepared, using N,N′‐methylene‐bis‐acrylamide as the crosslinking agent. The crosslinked resins were functionalized by the reaction with ethylene diamine to get amino group capacities varying from 4.2 to 1.1 mequiv/g. The maximum adsorption capacities of the lightly crosslinked resin for Fe3+, Fe2+, Ni2+, and Cu2+ are 3.62, 4.22, 1.48, and 1.67 mequiv/g, respectively. The adsorbed metal ions can be quantitatively desorbed. The adsorption rate and the influence of pH on the adsorption of metal ions were examined. The resins can be used for the separation between different metal ions as well as the ions in different valence states (e.g., Fe3+ and Fe2+). The resin is amenable for continuous process and can be regenerated several times.
Rolling and roll‐drawing of ultrahigh molecular weight polyethylene reactor powders
Authors: Wang Li‐Hui , Porter Roger S.
Published: April 2003

Ultrahigh molecular weight polyethylene (UHMWPE) reactor powders have been found to be processable in the solid state by the techniques of rolling and roll‐drawing. Plates of compacted UHMWPE reactor powder were prepared below their melting points. These plates were then rolled at 124°C. The maximum uniaxial draw ratio (DR) obtained by multiple rolling was about 10. In additional experiments, rolled plates of a DR of 6 were further drawn by tensile stretching at a temperature of 135°C. The specimens prepared by rolling and by the two‐stage draw were characterized by tensile measurements, differential scanning calorimetry (DSC), and X‐ray diffraction. Results show that, on rolling alone, the tensile modulus and tensile strength achieved were 3 GPa and 42 MPa, respectively, at a DR of 9.6. The rolled plates were effectively drawn further to a total DR of 86. Such highly drawn films exhibited tensile moduli and tensile strength up to 81 and 1.3 GPa, respectively. A high crystallinity and high crystal orientation were also obtained by the two‐stage draw.
Polystyrene/polyethylene terephthalate/polystyrene‐block–polycaprolactone blends: Emulsification and mechanical performance
Authors: Mckay Ian D.
Published: April 2003

A polystyrene‐polycaprolactone diblock copolymer was extrusion blended with polystyrene and polyethylene terephthalate. The morphologies of the resultant blends were studied using differential scanning calorimetry and scanning electron microscopy. In all compositions studied, the polystyrene and polyethylene terephthalate phases exhibited discrete glass transitions indicative of the immiscibility of these components. However, addition of the copolymer increased the extent of dispersion of the homopolymer components within one another quite effectively. Blend specimens were tested with respect to tensile, flexural, impact, and thermal performance characteristics to study the effects of morphology and composition on these factors. In general, the blends were rigid, brittle materials with some‐what enhanced thermal characteristics. Addition of polystyrene‐block‐polycaprolactone polymer to the blends resulted in increased brittleness, slightly reduced thermal performance, and, in some instances, greatly increased rigidity.
Unsaturated polyesters, III. Polyester from maleic anhydride and 1,4‐butylene glycol
Authors: Larez V. Cristobal J. , Mendoza Gilberto A. Perdomo
Published: April 2003

The polyesterification reaction of maleic anhydride and 1,4‐butylene glycol was carried out, using p‐toluensulphonic acid as catalyst. The resulting material was characterized by IR and H1‐NMR spectroscopy, end group analysis, and gel permeation chromatography. It is shown that there is a relationship between maleate to fumarate isomerization and steric interaction among condensed groups on the one hand and the tendency of the reacting system to crosslink or gel.
Effect of cholesteryl additive on poly(ethyl methacrylated)–poly(vinyl acetate) blend
Authors: Deshpande Dinkar D. , Basu Chandana , Panday Madhav
Published: April 2003

Three different compositions (9 : 1, 7 : 3, and 1 : 1) of poly(ethyl methacrylate) (PEMA) and poly(vinyl acetate) (PVAc) are chosen to check the miscibility of a polymer pair. The 9 : 1 and 7 : 3 PEMA‐PVAc blends are immiscible and have shown two distinct loss peaks in dynamic mechanical analysis (DMA) studies, while 1 : 1 PEMA‐PVAc has shown a single loss peak. Immiscible composition 7 : 3 PEMA‐PVAc is selected to study the effect of cholesteryl additives on the miscibility of the polymers. The additives chosen for the present studies are cholesteryl chloride, cholesteryl caprylate, and cholesteryl laurate. The DMA studies showed that all the additives caused a merging of the two loss peaks into one. X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) studies of the blend and blend with additive samples are utilized to get further information. The FTIR studies do not show any detectable change. The SEM micrographs of the blend and cholesteryl additive systems show a single‐phase ordered structure, and XRD data studies indicate the presence of small crystallites.
Catalyst effects found in thermal and mass spectrometric analyses of polycarboxylic acids used as durable press reactants for cotton
Authors: Trask‐Morrell Brenda J. , Andrews B. A. Kottes , Graves E. E.
Published: April 2003

Effective polycarboxylic acids (PCAs) crosslink cotton cellulose by an ester linkage and smooth‐drying fabrics are produced. The presence of a catalyst improves the crosslinking reaction. A series of seven PCAs was examined by thermal analytical (TA) and mass spectrometric (MS) techniques. The focus of this research was to discover if catalyst effects were measurable by TA and MS and to seek additional support for a proposed mechanism of cellulose/organic acid reactivity via acid anhydride formation. Thermal analyses consisted of differential scanning calorimetric (DSC) and thermogravimetric (TG) procedures. MS analyses, using the electron impact mode, were performed by direct probe sample insertion. Observed catalyst effects included shifts in peak positions to lower temperature/time, and were noticeable primarily in MS‐reconstructed ion current chromatograms and DSC thermograms. Two TG parameters, the amount of residue produced and the rates of weight loss, offer ways to predict the effectiveness of a PCA with respect to smooth‐drying character. The presence of the catalyst influenced both measurements in desirable directions. Finally, the catalyst did not alter TG water loss data that support the proposed mechanism of reaction with cellulose via an anhydride intermediate.
Vulcanization of rubber. Kinetic parameters for SBR and simulations of vulcanization in a mold
Authors: Jönsson Kersti , Flodin Per
Published: April 2003

Differential scanning caiorimetry (DSC) was used to characterize the vulcanization of styrene‐butadiene rubber (SBR). The effect of three different fillers on the vulcanization process was also investigated. The fillers used were carbon black HAF and SRF and silica. The calculated reaction orders, activation energy, reaction energy, and preexponential factor, completed with physical properties, were used to calculate the temperature and extent of reaction inside a mold with time. The mathematical model used yields that are in fair agreement with experimental temperature measurements inside the mold.
Preparation and characterization of maleimide‐terminated poly(arylene ether sulfone) oligomers of various molecular weights
Authors: Jin Shijiu , Yee Albert F.
Published: April 2003

A new variation in the bismaleimide (BMI) resin family, maleimide‐terminated poly(oxy‐1,4‐phenylene sulfonyl‐1,4‐phenylene) oligomers, has been synthesized. The preparation of oligomers (n = 1–12) is described in this study. The structure of these oligomers is characterized by FT‐IR and NMR spectroscopy. These oligomers are light yellow to light gray powders that can be melted or dissolved in solvents. Their terminating group bismaleimide has relatively high reactivity. Therefore, these BMI resins can be cured at 250°C to form a crosslinked product. Since the backbone chain is poly(arylene ether sulfone), the cured polymers have high Tg's, which increased from 220°C to higher than 340°C as the number of repeating units n of the corresponding oligomers decreases.
Separation of liquid mixtures by using polymer membranes. I. Water–alcohol separation by pervaporation through PVA‐g‐MMA/MA membrane
Authors: Chiang Wen‐Yen , Hu Chun‐Min
Published: April 2003

A membrane was designed for the separation of a water–alcohol mixture by pervaporation on the basis of the difference in hydrogen‐bonding interaction between two components of the membrane. Two kinds of poly(vinyl alcohol)‐g‐maleic anhydride/methyl methacrylate membrane were prepared by different methods: (1) A homogeneous membrane was formed by casting from dimethyl sulfoxide solution after purification. (2) A porous membrane was obtained directly by casting from the reaction solution, and then was purified. It is found that water was permeated through a homogeneous membrane preferentially in all ranges of feed compositions. Moreover, the flux was found to decrease with increasing PVA content in the membrane. The porous membrane after heat treatment has selective permeability for methanol. Pervaporation of water was investigated with respect to the feed concentration and also to the operating conditions. The effect of the molecular size of the permeating species on both permeation and separation is also discussed.
The mechanism for occurrence of internal stress during curing epoxide resins
Authors: Ochi Mitsukazu , Yamashita Kiichi , Shimbo Masaki
Published: April 2003

The mechanism for the occurrence of internal stress in the curing cycle of four‐functional epoxide resins was investigated in detail. The internal stress in this system was generated at the vitrification point in the course of curing, because the modulus of samples was rapidly increased at this point. After the vitrification point, the internal stress was increased with an increase of the shrinkage in the curing and cooling processes.

Moreover, the magnitude of the internal stress in the four‐functional resin systems depended on the chemical structure of aromatic diamines used as curing agents. This was explained by the difference of curing shrinkage after vitrification in each system.
Crystallization behavior of polypropylene filled with surface‐modified calcium carbonate
Authors: Mitsuishi Kazuta , Ueno Satoru , Kodama Souji , Kawasaki Hitoshi
Published: April 2003

Polypropylene (PP) and calcium carbonate (CaCO3) were mixed in a two‐roll mill. The mixed compounds were molded on the plate by using a compression press heater. To improve the affinity of the relation between CaCO3 and the PP matrix, we modified the CaCO3 surface through chemical reaction with alkyl dihydrogen phosphates. The CaCO3 content and size modification affected the crystallization behavior of the filled PP composites. The crystallization temperature in the nonisothermal crystallization process increased with the increase of CaCO3 content and the decrease of CaCO3 size. The crystallization temperature revealed the function of log (1 + Ts) (Ts, total surface area of CaCO3) irrespective of CaCO3 content and size for modified and unmodified systems, respectively. The shoulder or double crystallization peak of PP composites is recognized for the unmodified system (particle sizes: 1.0 and 4.5 μm).
Polymer aqueous solutions as quenching media. II. Ethylene oxide–propylene oxide copolymers
Authors: Louai Abderrahim , Pollet Gilbert , Francois Jeanne , Moreaux Francois
Published: April 2003

The cooling power of aqueous solutions of ethylene oxide‐propylene oxide copolymers are studied with a silver standard sample by using two apparatuses quench with injection and quench with agitation. For temperature T>400°C, the viscosity plays the predominant role; for T<400°C, the cooling is controlled by the polymer precipitation and the cooling rate decreases by lowering the cloud point of the polymer solution. This work demonstrates the possibility of adjusting the cooling curves by taking into account the thermodynamical properties of the polymer.
Synthesis and rheological properties in aqueous solution of poly(acrylamide‐co‐sodium allylsulfonate)
Authors: Kejun Yao , Guowei Zhuo
Published: April 2003

The copolymerization of acrylamide (AM) with sodium allylsulfonate (SAS) was studied. The copolymerization rate equation was determined, Rp = K[KPS]0.70[AM]1.60[SAS]−0.60. The copolymeric composition obtained by nitrogen and sulfur elemental analysis, and 1H‐NMR method. The reactivity ratios were calculated by the Kelen–Tudos method and the value of r1(AM), r2(SAS) was determined to be 2.45 and 0.060, respectively. The rheology of aqueous solution of synthetic poly(acrylamide‐co‐sodium allylsulfonate) was determined at different temperatures and flowing activation energy Eη were calculated.
Thermal behavior and cured products of fluorine‐containing bismaleimides
Authors: Nagai Akira , Takahashi Akio , Suzuki Masahiro , Mukoh Akio
Published: April 2003

Thermal behavior of fluorine‐containing bismaleimides was investigated by differential scanning calorimetry and the effects of introducing fluorine groups on thermal behavior and properties of cured products were discussed. The melting point was lower and the polymerization temperature was higher with increasing fluorine content. This decrease in polymerization reactity of fluorine‐containing bismaleimide was explained by the stabilization energy of the double bond or the bismaleimide molecule itself as calculated by the MNDO or MM method. Thermal polymerization of the double bond was interpreted by an autocatalytic reaction mechanism in which the activated biradical product accelerated the radical propagation. It was found that the fluorine‐containing cured product had good thermal stability and a low dielectric constant.
Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(styrene‐co‐acrylonitrile) and poly(p‐methylstyrene‐co‐acrylonitrile)
Authors: Goh S. H. , Lee S. Y. , Leong C. L.
Published: April 2003

The miscibility of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(styrene‐co‐acrylonitrile) (SAN) and poly(p‐methylstyrene‐co‐acrylonitrile) (pMSAN) was studied by differential scanning calorimetry. PMOMA is miscible with SAN having an acrylonitrile (AN) content around 30 wt %. However, PMOMA is immiscible with any of the pMSAN having AN contents between 9 and 36 wt % and with pMSAN having AN contents between 19 and 34 wt %. The miscibility of the blends enables the evaluation of various segmental interaction parameters.
Miscibility behaviour of bisphenol‐A polycarbonate and poly(para‐chlorostyrene)
Authors: Krings L. H. M. , Buning G. H. Werumeus , Nies E.
Published: April 2003

The miscibility behaviour of bisphenol‐A polycarbonate (PC) and poly(para‐chlorostyrene) (PpCIS) has been investigated. Special attention has been paid to the influence of the molar mass of PpCIS. Molar masses varying from 10 to > 1,000 kg/mol were used. The blends were studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning and transmission electron microscopy (SEM and TEM). It was concluded that the blends of all three PpCIS grades and PC phase separate. In the low concentration region, some intermixing was found, especially for the blend with the low molar mass PpCIS. The most important effect of lowering the molar mass of PpCIS was an acceleration of the phase separation. The combination of SEM with electron probe X‐ray microanalysis (EPMA) gave qualitative information on the miscibility behaviour and was found to be a useful extension of routine microscopy techniques used in blend studies.
The effect of annealing on the thermal and dynamic mechanical properties of para‐tetramethyl xylene diisocyanate‐based polyurethanes
Authors: Stack G. M. , Beumel L. L.
Published: April 2003

A series of polyurethane elastomers based on the para‐Tetramethyl Xylene diisocyanate group were annealed at temperatures from 100 to 180°C. These high‐temperature exposures were found to raise significantly the peak melting point of the urethanes that contained crystalline hard segments. The corresponding enthalpy of fusion was found to decrease after annealing at the higher temperatures. In most cases, the annealings caused a slight increase in the soft‐segment glass transition temperature, indicating that some increase in phase mixing had occured. Dynamic mechanical measurements indicated that the annealings caused a slight reduction in the Young's modulus and a broadening of the loss–tangent peak. The broadening of the loss–tangent peak can be attributed to the increased phase mixing induced by the annealings. The large increases in melting point induced by annealing do not appear to significantly affect the subsequent dynamic mechanical properties.
Characterization of linear low density polyethylene by temperature rising elution fractionation and by differential scanning calorimetry
Authors: Karbashewski Elizabeth , Kale L. , Rudin A. , Tchir W. J. , Cook D. G. , Pronovost J. O.
Published: April 2003

In this article we consider characterization of the branching distribution of LLDPE by analytical TREF and by DSC techniques. Qualitatively, both methods yield parallel information, provided that the DSC samples are prepared at very slow cooling rates. Analytical TREF provides more quantitative information, however, in that the mass fraction of material with different branch levels can be estimated. Full characterization of a polyethylene requires the use of a preparative TREF technique, in which fractions dissolved at preselected temperatures are investigated for branching with high resolution 13C NMR and for molecular weight distribution, with high temperature SEC analyses.
Transport properties in polypyrrole–PVA composites: Evidence for hopping conduction
Authors: Makhlouki Mohamed , Morsli Mustapha , Bonnet Alain , Conan Alain , Pron Adam , Lefrant Serge
Published: April 2003

Experimental results on electrical conductivity and thermoelectric power for FeCl3‐doped polyvinyl alcohol‐polypyrrole composites, with polypyrrole content exceeding the percolation threshold, are presented. The electrical conductivity is analyzed in terms of the hopping theory, whereas the thermoelectric power displays a metallic‐like dependence. A model involving both the intrinsic resistance of the fibrils (V.R.H. hopping mechanisms) and the resistance of the junctions between fibrils (fluctuations‐induced tunneling conduction) has been retained.
Novel effect of barbituric acid on glass transition temperature of bismaleimide–epoxy resin systems
Authors: Pan Jing‐Pin , Shiau Gwo‐Yuh , Chen Ker‐Ming
Published: April 2003

Barbituric acid (BTA) has a novel influence on glass transition temperature (Tg) of bismaleimide (BMI)–epoxy resin systems. It causes the Tg of a BMI–epoxy resin system to rise significantly. The BTA's influence on Tg was investigated by changing the molar ratio of the reactants. In addition, the influence of benzoperoxide (BPO) on Tg was compared with that of BTA. The reaction selectivity of BTA and diamino‐diphenyl sulfone (DDS) toward BMI and epoxy individually in the BMI–epoxy blended systems were studied using the DSC and GPC. By controlling the amount of DDS and BTA, epoxy and BMI could form intercrosslinking networks.
Hydrophilic elastomer containing poly(tetrahydrofuran) segments and viologen units
Authors: Kohjiya Shinzo , Hashimoto Tamotsu , Yamashita Shinzo
Published: April 2003

Elastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units was prepared by living cationic polymerization of tetrahydrofuran (THF), followed by the end capping of the living polymer by 4,4´‐bipyridine. The obtained ionene‐type polymer (PTV) exhibited low tensile modulus and high tensile strength with large extensibility, i.e., it is an excellent elastomer from its mechanical properties. The water swelling behavior and effects of water and the sort of counter anions on the tensile properties of PTV were investigated. PTV showed high hydrophilicity; e.g., the water content of PTV with bromide counter anions was ca. 40% after swelling in water at 25°C for 24 h. However, even for the samples with such a high water content, PTVs displayed good elastomeric properties, although the tensile modulus and tensile strength were decreased with increase of water content. The hydrophilicity of PTV was found to depend on the kind of counter anions, which in turn determined the tensile properties of PTVs in a swollen state.
Molecular mobility in wool fibers as determined from nuclear magnetic resonance studies
Authors: Rao D. Rama , Gupta V. B.
Published: April 2003

The mobility of protons in wool samples of Lincoln, Chokla, and Merino, equilibrated to various moisture contents in the range of 0–98% relative humidity (RH), have been studied by pulsed nuclear magnetic resonance (NMR) technique. Peak height and peak width were determined from absorption and derivative curves and the relaxation times T1 and T2 were determined from relaxation curves. The mobility increases with increase in moisture content. Among the three wools, the mobility was high in Merino as compared to the other two wools. The differences in the measured mobilities were related to structural and morphological differences in the three wools. The present analysis suggests that water in wool has at least three different associations, each with a different binding energy.
New class of cellulose fiber spun from the novel solution of cellulose by wet spinning method
Authors: Yamashiki Takashi , Matsui Toshihiko , Kowsaka Keisuke , Saitoh Masayoshi , Okajima Kunihiko , Kamide Kenji
Published: April 2003

A novel cellulose solution, prepared by dissolving an alkali‐soluble cellulose, which was obtained by the steam explosion treatment on almost pure natural cellulose (soft wood pulp), into the aqueous sodium hydroxide solution with specific concentration (9.1 wt %) was employed for the first time to prepare a new class of multifilament‐type cellulose fiber. For this purpose a wet spinning system with acid coagulation bath was applied. The mechanical properties and structural characteristics of the resulting cellulose fibers were compared with those of regenerated cellulose fibers such as viscose rayon and cuprammonium rayon commercially available. X‐ray analysis shows that the new cellulose fiber is crystallographically cellulose II, and its crystallinity is higher but its crystalline orientation is slightly lower than those of other commercial regenerated fibers. The degree of breakdown of intramolecular hydrogen bond at C3[Xam(C3)] of the cellulose fiber, as determined by solid‐state cross‐polarization magic‐angle sample spinning (CP/MAS) 13C NMR, is much lower than other, and the NMR spectra of its dry and wet state were significantly different from each other, indicating that cellulose molecules in the new cellulose fiber are quite mobile when wet. This phenomenon has not been reported for so‐called regenerated cellulose fibers.
Thermal studies on brominated atactic polypropylene
Authors: Mukherjee A. K. , Mohan Anita
Published: April 2003

Thermal behavior of brominated atactic polypropylene (BAPP), obtained by thermal bromination of atactic polypropylene (APP), was evaluated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). It was found that the initial decomposition temperature (IDT) and char yield increase with the increase in bromine content while integral procedural decomposition temperature (IPDT) showed a decreasing trend. A comparative study of these value in inert and oxidative atmospheres has been made. DTA study shows that onset decomposition temperature (ODT) and glass transition temperature (Tg) increase with the increase in degree of bromination. The possible reasons for the occurring phenomena have been discussed.
Photosynthesis and application of polyfunctional poly(n‐butyl acrylate) elastomers for use in epoxy resin toughening
Authors: Wang Hong‐Bing , Li Shan‐Jun , Ye Jin‐Yong
Published: April 2003

Medium molecular weight, novel polyfunctional elastomers, namely epoxy groups on poly(n‐butylacrylate) (ETPnBA) and carboxyl groups on poly(n‐butylacrylate) (CTPnBA) were photosynthesized for evaluation as the toughening agents in epoxy resins. The effect of the functionality and kind of functional group of the elastomers upon the toughening of epoxy resins modified with these rubbery copolymers as a second phase was investigated by tensile tests, impact test, and electron microscopy. It was found that there exists an optimum functionality of elastomers for maximum impact resistance in epoxy groups (ETPnBA) and carboxyl groups (CTPnBA) copolymer‐modified systems. Studies on morphology of the modified epoxy resin system indicated that the better toughening effects of multiple distribution of particle sizes. The aggregation of rubber particles occurring in carboxyl group CTPnBA modified epoxy resin caused a loss of toughness.
The interfacial polycarbonate reactions. I. Defining the critical process parameters
Authors: Gu Jen‐Tau , Wang Chun‐Shan
Published: April 2003

Polycarbonate is prepared by the interfacial phosgenation and polycondensation of bisphenol A (BPA) in methylene chloride with caustic using triethylamine as a catalyst. In a typical batch reactor, where phosgenation and oligomerization proceed simultaneously, the critical process parameters are intermingled and are difficult to determine. Therefore, a semicontinuous process consisting of a series of static mixers for continuous phosgenation, followed by a batch reactor for oligomerization and polycondensation, was developed for better understanding of the reaction mechanisms. Phosgene hydrolysis was reduced greatly going from a batch to a continuous reactor (excess phosgene was reduced from 30 to 5%). Variables which influence the composition of intermediates are linear velocity, organic to aqueous volume ratio, PH (BPA to NaOH ratio), and phosgene to BPA ratio. These variables also affect BPA conversion, amount of phosgene hydrolysis, terminator capping efficiency, molecular weight, and molecular weight distribution of the resulted polycarbonate. Oligomerization takes place at the interface, and monochloroformates (HO‐Bn‐OCOCI) which contain both hydrophilic and lipophilic end groups, stay at the interface and, hence, react preferentially. Oligomers are analyzed by a newly developed HPLC technique.
Polymerization of acrylamide initiated with electrogenerated cerium (IV) in the presence of EDTA
Authors: Saraç A. Sezai , Erbil Candan , Soydan A. Bahattin
Published: April 2003

Polymerization of acrylamide was carried out with cerium (IV)‐EDTA redox initiator system with and without electrolysis. The effect of temperature, time, cerium (IV), and EDTA concentrations on the polymerization yield and molecular weight were studied and compared with electrolytic conditions. At low concentrations of cerium (IV) the electrolytic method continuously supplying Ce (IV) from Ce (III) has an advantage over the nonelectrolytic method for which polymerization did not occur under these conditions. A possible polymerization mechanism is suggested.
The determination of the pore structural parameters of isoporous resins by inverse GPC
Authors: Wang Anyou , Yan Juntan , Xu Rongnan
Published: April 2003

The swollen pore structure of a series of microporous isoporous resins (7.4–140 Å) are investigated with inverse GPC, n‐alkylbenzenes and linear polystyrenes being used as probe molecules. The results indicated that, with the lowering of crosslinking degree of isoporous resins, the average pore diameter increased and the pore distribution curve broadened. All pore volume distribution obeyed a log‐normal distribution. Based on the linear regression method, the experimental data were fitted to a monotonously declining exponential function and a normal distribution function by a computer, and some important structural parameters such as average pore diameter, pore volume distribution, specific surface area, etc. were obtained. The specific surface area of swollen gels were found much greater than those in the dry state measured by N2 adsorption.
Cellulose nitrate–poly(vinyl chloride‐co‐vinyl acetate)–polyurethane ternary IPNs: FT‐IR and morphological studies
Authors: Natchimuthu N. , Rajalingam P. , Radhakrishnan Ganga
Published: April 2003

Ternary semi‐IPNs of nitrocellulose, poly(vinyl chloride‐co‐vinyl acetate), and polyurethanes have been synthesized and characterized by FT‐IR, SEM, and differential scanning calorimetry. Semi‐IPNs of nitrocellulose‐polyurethanes are found to be incompatible whereas the ternary system consisting of nitrocellulose‐poly(vinyl chloride‐co‐vinyl acetate) and polyurethanes is partially compatible. Hydrogen bonding interactions are discussed based on the FT‐IR analysis. The tensile strength and percent elongation are interpreted on the basis of the NCO/OH ratio and composition.
Spectroscopic study of polytoluidines in the UV‐visible and IR regions
Authors: Fujita Iwao , Ishiguchi Mitsuharu , Shiota Hiroshi , Danjō Takeshi , Kosai Kouichi
Published: April 2003

Electropolymerization of o‐toluidine(o‐methylaniline) and m‐toluidine was carried out in acidic aqueous solution, and UV‐visible and IR spectra of the resulting polymer films were obtained at various electric potentials and pHs. In Na2SO4 aqueous solution, poly(o‐toluidine) gave considerably different UV‐visible spectra from polyaniline, whereas, in HCl (pH ∼ 0), the spectra of poly(o‐toluidine) changed in the same way as polyaniline when the potential was varied. This spectral change depended also on counterion. This suggests that the intermediate state (radical cation) of poly(o‐toluidine) is unstable in a neutral solution especially when a large counter ion exists, which is contrast to polyaniline. The dependency of the FT‐IR spectra of poly(o‐toluidine) on the potential and pH supported also the above result of UV‐visible spectra. From both UV‐visible and IR spectra under various conditions, it was found that o‐toluidine and m‐toluidine give the same polymer.
Preparation of colloidal silver using various reductants in the presence of copolymers of vinyl alcohol‐N‐vinyl pyrrolidone
Authors: Esumi Kunio , Ishizuki Norio , Torigoe Kanjiro , Nakamura Hideuki , Meguro Kenjiro
Published: April 2003

Colloidal silver was prepared using various reductants such as hydrazine, ascorbic acid, ribose, and hydrogen in aqueous solution in the presence of copolymers of vinyl alcohol‐N‐vinyl pyrrolidone. The average particle size of colloidal silver decreased with increasing amount of copolymers added. The reduction by hydrogen provided smaller silver particles compared with the other reductants. The stability of colloidal silver against AlCl3 increased with increasing amount of copolymers added.