bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of ultrahigh molecular weight polyethylene fibers by plasma treatment. II. Mechanism of surface modification
Authors: Gao Shanglin , Zeng Yeguang
Published: April 2003

A detailed examination has been undertaken of the influence of surface treatment on the adhesion of ultrahigh molecular weight polyethylene (UHMW‐PE) fibers to epoxy resin. XPS, SEM, FTIR–ATR, LRS, and contact‐angle measurements have been used to characterize the chemical and physical changes of the fibers. The results, taken together, suggest that the adhesion depends on three factors: (i) chemical bonding effects, after plasma treatment, with the introduction of various kinds of oxygen‐containing groups into the surface of the nonpolar polyethylene, which greatly improve the surface energy of the fibers; (ii) mechanical keying effects; and (iii) the nonpolar dispersion force. It is concluded that these three factors can be regarded as additive and the contributions from each of them to fiber/resin adhesion are different and change with increasing treatment time. The optimum results are obtained when their respective contribution reaches about 60%, 30%, and 10%. © 1993 John Wiley & Sons, Inc.
Separation of liquid mixtures by using polymer membranes. IV. Water‐alcohol separation by pervaporation through modified acrylonitrile grafted polyvinyl alcohol copolymer (PVA‐G‐AN) membranes
Authors: Chiang Wen‐Yen , Huang Ching‐Chong
Published: April 2003

The acrylonitrile (AN) grafted onto polyvinyl alcohol (PVA) can improve the mechanical properties and water resistance of PVA; however, its hydrophilicity is decreased. Prepared PVA‐g‐AN membranes through modification with the NaOH and HCHO aqueous solutions can enhance its hydrophilicity. This modified PVA‐g‐AN membranes were used to separate alcohol/water solution with the pervaporation method. The flux was increased from 0.72 kg/m2 h of the original membrane to 2.06 kg/m2 h of the modified membrane. Moreover, adding a small quantity of CoSO4 to the water‐alcohol mixture can simultaneously increase the separation factor. © 1993 John Wiley & Sons, Inc.
An attempt to simulate the bowing phenomenon in tenter with simple models
Authors: Yamada Toshiro , Nonomura Chisato
Published: April 2003

The bowing phenomenon throughout a tenter was experimentally observed with a pilot plant of successive biaxial stretching. The observed results were compared with simulated ones, by which the deformation behaviors of film in a tenter were predicted, with the assumption that the film was homogeneous isotropic, homogeneous anisotropic, heterogeneous isotropic, or heterogeneous anisotropic for a two‐dimensional elastic body with an FEM. Comparatively good agreement between the simulated and observed results was obtained for a heterogeneous anisotropic elastic body with an initial mesh, involving in advance a plastic deformation part. © 1993 John Wiley & Sons, Inc.
Modeling poly(vinyl alcohol)‐stabilized vinyl acetate emulsion polymerization. I. Theory
Authors: Gilmore C. M. , Poehlein G. W. , Schork F. J.
Published: April 2003

A mathematical model for particle nucleation and growth in the isothermal semibatch emulsion polymerization of vinyl acetate stabilized with poly(vinyl alcohol) is presented. In addition to the particle nucleation and growth mechanisms governing ionically stabilized polymerizations of relatively water‐soluble monomers, the model accommodates grafting onto the poly(vinyl alcohol) backbone during nucleation, and polymeric stabilization. The user supplies the emulsion recipe, process conditions and kinetic parameters, and the model predicts the various species concentrations, along with the conversion and particle size and number profiles. In part II, model predictions are discussed. © 1993 John Wiley & Sons, Inc.
Modeling poly(vinyl alcohol)‐stabilized vinyl acetate emulsion polymerization. II. Comparison with experiment
Authors: Gilmore C. M. , Poehlein G. W. , Schork F. J.
Published: April 2003

The mathematical model presented in Part I, accommodating the emulsion polymerization of vinyl acetate stabilized with poly(vinyl alcohol), predicts experimental conversion and particle size data with reasonable accuracy. Model predictions of measurable variables exhibit sensitivity to variables affecting either primary ungrafted particle nucleation of flocculation kinetics, but are relatively insensitive to variables affecting poly(vinyl alcohol) grafting reactions and the resulting primary grafted particle concentration. Semibatch simulations indicate that independent increases in the vinyl acetate, poly(vinyl alcohol), and initiator levels of all increase the primary grafted particle population. It is unlikely, however, that this population exceeds the ungrafted counterpart under most commercial polymerization conditions. This relative insignificance of grafting during particle nucleation is also noted in literature data simulations where, with appropriate parameter adjustments, the model predictions agree well with the batch, thermal initiation data. © 1993 John Wiley & Sons, Inc.
Morphology‐permeability relationships in biaxially oriented Pet films: A relationship between oxygen permeability and PROF
Authors: Gohil Ramesh M.
Published: April 2003

The effect of uniaxial and biaxial film‐processing parameters on the orientation of the phenyl ring in the crystalline and amorphous phases has been evaluated using a variety of techniques. It has been demonstrated that the total phenyl ring orientation factor (PROF) measured from refractive indices can reflect the nature of amorphous and crystalline phases as well as morphological changes taking place due to variation in processing conditions. The PROF parameter can, therefore, offer a useful relationship to predict oxygen perme‐ability for biaxially oriented PET films prepared under a variety of processing conditions. The cause of nonlinearity of oxygen permeability with birefringence, percent crystallinity, and tan δ maximum peak temperature (MPT) is discussed in detail. © 1993 John Wiley & Sons, Inc.
Anomalous dependence of the size of droplets of disperse phase on intensity of mixing
Authors: Fortelný I. , Černá Z. , Binko J. , Kovář J.
Published: April 2003

The dependence of phase structure on the intensity of mixing was studied for two modified polyamide/[poly(phenylene oxide) + polystyrene] (50/50) blends with different viscosity ratios of components. In these blends, polyamide forms the matrix and the mixture of miscible polymers [poly(phenylene oxide) and polystyrene] forms the disperse phase at all rates of mixing. The average size of the droplets of the disperse phase grows with increasing rate of mixing. This (rather surprising) result is explained as a consequence of the dynamic equilibrium between breakup and coalescence of droplets in a highly concentrated system at the condition of steady mixing. Generally, the dependence of droplet size on rate of mixing is not necessarily a monotonic function for blends with a high content of the disperse phase. © 1993 John Wiley & Sons, Inc.
Transport characteristics and other physicochemical properties of aged poly(1‐(trimethylsilyl)‐1‐;propyne)
Authors: Yampol'Skii Yu. P. , Shishatskii S. M. , Shantorovich V. P. , Antipov E. M. , Kuzmin N. N. , Rykov S. V. , Khodjaeva V. L. , Platé N. A.
Published: April 2003

Samples of poly[1–(trimethylsilyl)–1–propyne] were kept for about 4 years in ambient conditions. The permeability and diffusion coefficients were examined and found to be decreased by 1–2 orders of magnitude. To ascertain the nature of the changes underwent during long‐term storage of this polymer, several physicochemical methods were applied: positron annihilation, wide‐angle X‐ray diffraction, spin probe, and density evaluation. These studies indicated that a decrease of free volume and more close chain packing took place during the aging process. IR spectroscopy and 13C‐NMR showed that oxygen‐containing products appeared in the polymer after long‐term storage. This should result in a certain decrease in the rigidity of the backbone chains and more intensive interchain in‐teractions, and, hence, in a decrease in the free volume of the aged polymer. © 1993 John Wiley & Sons, Inc.
Melt rheology and elasticity of natural rubber—ethylene–vinyl acetate copolymer blends
Authors: Koshy Alex T. , Kuriakose Baby , Thomas Sabu , Premalatha C. K. , Varghese Siby
Published: April 2003

The melt rheology of blends of natural rubber (NR) and ethylene–vinyl acetate copolymer (EVA) has been studied with reference to the effects of blend ratio, cross‐linking systems, shear stress, and temperature. When EVA formed the dispersed phase, the viscosity of the blends was found to be a nonadditive function of the viscosities of the component polymers at lower shear region, i.e., a positive deviation was observed. This behavior has been explained based on structural buildup of dispersed EVA domains in the continuous NR matrix. The effect of the addition of silica filler on the flow characteristics of the blends has been investigated. The melt elasticity parameters such as die swell, principal normal stress difference, recoverable shear strain, and elastic shear modulus of NR–EVA blends were also evaluated. © 1993 John Wiley & Sons, Inc.
On the critical molecular chain length of polydimethylsiloxane
Authors: Dvornic Petar R. , Jovanovic Jelena D. , Govedarica Milutin N.
Published: April 2003

Because a study of the results reported for the chain dimensions of polydimethylsiloxane (PDMS), critical for the onset of this polymer's non‐Newtonian flow behavior, obtained from the viscosity‐molecular weight relationships available from the literature, clearly revealed that considerable differences exist between the reported data, a detailed analysis of these data was performed together with an additional examination of 10 new PDMS samples that were selected so as to have molecular weights that would fill the gaps observed in the polymer viscosity–chain length relationship constructed from the accepted literature data. The results obtained were analyzed by using several different procedures integrated into a recently described comparative method that could allow for determination of what is called the most realistic critical value, Zwc. The latter was determined as 930 PDMS main‐chain atoms, which corresponds to this polymer's degree of polymerization of 464.5 and the weight‐average molecular weight of 34,500. It is not only shown that after elimination of some clearly erroneous data points from the previously reported relationships the obtained critical chain‐length values could very well fit the earlier relationships, but also that appropriate “master” relationships were constructed including 48 pairs of the old and 10 pairs of the new data points. It is suggested that this relationship be accepted as the best‐fit viscosity–polymer chain‐length dependence for PDMS, and it is pointed out that the obtained PDMS critical chain‐length value ranks this polymer's macromolecules as the most flexible of the corresponding long‐chain molecules presently known. © 1993 John Wiley & Sons, Inc.
Mechanical and thermal properties of UV‐curable polyurethane and polyurea acrylates
Authors: Yu Xuehai , Grady Brian P. , Reiner Richard S. , Cooper S. L.
Published: April 2003

Soft‐segment molecular weight, soft‐segment crystallization, hard‐segment‐type, and reactive diluent level were examined in urea and urethane acrylates. Increasing soft‐segment molecular weight led to a decreased tensile modulus, increased strength, and increased elongation at break. Soft‐segment crystallization increased the modulus below the melting temperature, but decreased the modulus above the melting temperature because crystallization interfered with cross‐linking. Materials with hard segments that allowed for greater phase separation showed a higher modulus, higher ultimate stress, and higher ultimate elongation. Materials with reactive diluents 2‐hydroxyethyl methacrylate (HEMA) and N‐vinyl pyrrolidinone (NVP) showed qualitatively different behavior. HEMA caused the modulus and strength to increase with little effect on elongation up to concentrations of 50 wt %; at higher concentrations, the elongation decreased. NVP also increased the modulus and strength; however, at 40 wt % NVP, ultimate elongation increased in a well‐phaseseparated system and decreased in a poorly phase‐separated system. In tensile tests, samples with 40% NVP also showed substantial sample necking and drawing. © 1993 John Wiley & Sons, Inc.
Studies on the dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites
Authors: Weibo Huang , Fengchang Zhan
Published: April 2003

The 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, Inc.
Formation of entanglements at brushlike interfaces in cellulose–polymer composites
Authors: Felix Johan M. , Gatenholm Paul
Published: April 2003

Cellulose fibers were grafted with compatibilizing agents, such as maleated polypropylenes of different molecular weights. Steric effects and surface free‐energy effects were found to stimulate the stretching of grafted chains away from the cellulose fiber surface, giving rise to a brushlike configuration in a polypropylene (PP) melt. Inverse gas chromatography measurements on modified fibers using a model compound for PP as adsorbate showed that interactions of PP and grafted fibers, which were mainly diffusion‐dependent, increased with increasing molecular weight of the compatibilizer. Dynamic mechanical measurements and tensile testing of composites showed that the presence of compatibilizing agents enhanced stress transfer and increased interphase thickness considerably, the most significant effect being obtained for the high molecular weight compatibilizers. Apparently, the longer the grafted chains, the larger the fraction of matrix molecules involved in the interactions and, thus, the thicker the interphase. The improvement of adhesion between treated fibers and PP, as detected by peel testing, was proven to be caused mainly by entanglements formed between compatibilizing agents and PP. © 1993 John Wiley & Sons, Inc.
Molecular redesign of expanded polystyrene to allow use of carbon dioxide as a foaming agent. I. Reversible binding of CO2
Authors: Diaf A. , Enick R. M. , Beckman E. J.
Published: April 2003

Environmental concerns, associated with the production of expanded plastics using hydrocarbon blowing agents, have spurred interest in environmentally‐friendly technology by which cellular materials, particularly expanded polystyrene, can be produced. Consequently, we have explored the possibility of using styrene‐based, amino‐functional copolymers to generate expandable systems, which would rely solely on CO2 as a blowing agent. Carbon dioxide is an attractive foaming agent in that it can be readily extracted from the air, is nonflammable, and exhibits low toxicity. Using a styrenic copolymer, functionalized with ethylenediamine (EDA), the results of this study show that aminated polymers are capable of reversibly binding weakly acidic gases, CO2 in particular. While the reaction products (polymer‐bound zwitterions) are stable under ambient conditions, decarboxylation can be thermally induced cleanly and easily. Work underway in our laboratory shows that microporous, as well as nonporous EDA‐functional copolymers, are effective, thermally‐reversible sorbents for acid gases. Furthermore, preliminary results show that these materials may also find potential applications in facilitated transport membrane technology. © 1993 John Wiley & Sons, Inc.
Surface acid‐base characteristics of fiber materials by contact angle measurements
Authors: Youan Mao
Published: April 2003

Contact angle measurements were used to study the surface acid‐base characteristics of treated and untreated carbon fibers, and of treated and untreated silicon carbide fibers. It has been shown that, when untreated, the surfaces of these two fibers exhibits “amphoteric,” but the base character is dominant. After oxidization in a liquid phase, the surface acid character of the carbon fibers changes little, whereas the base character becomes much stronger. The treatment, with boiling‐concentrated HNO3 for three hours and the sintering treatment in air at 500°C for eight hours, has little effect on the surface acid‐base characteristics of the silicon carbide fibers. © 1993 John Wiley & Sons, Inc.
Porous membrane of polydimethylsiloxane by hydrosilylation cure: Characteristics of membranes having pores formed by hydrogen foams
Authors: Kobayashi Takaomi , Saitoh Hitoshi , Fujii Nobuyuki , Hoshino Yoshikazu , Takanashi Masanori
Published: April 2003

Porous polydimethylsiloxane (PDMS) membranes were prepared by catalytic hydrosilyiation cure of a silicone compound containing a vinyl group and a SiH group in the presence of additives such as water, ethanol, ethylene glycol, and 2‐methoxyethanol. The pores were formed in the membrane as a result of hydrogen foams produced by the reaction between the SiH group and the OH group of the additive during the cure. The cure reaction, hydrogen generation, and properties of the porous membranes that resulted were examined as a function of the additive concentration in the compound at various cure temperatures. As application of the membrane, the ultrafiltration properties were determined. © 1993 John Wiley & Sons, Inc.
Crystallinity in the polypropylene/cellulose system. I. Nucleation and crystalline morphology
Authors: Quillin Daniel T. , Caulfield Daniel F. , Koutsky James A.
Published: April 2003

The amount of research on lignocellulosic/thermoplastic composites has increased dramatically. Little attention, however, has been directed towards the subject of crystallinity at the interface (interphase). Optical microscopy and differential scanning calorimetry were used in this work to study crystallinity in the cellulose/polypropylene system. The results verify that cellulose acts as a nucleating agent for polypropylene, producing a transcrystalline region around the fiber. Treatment of the fibers with alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), or stearic acid, inactivates the surface features responsible for transcrystallinity. These treatments also affect the overall degree of crystallinity of the sample. Morphological features, resulting from a transcrystalline or nontranscrystalline interphase, may have a significant effect on mechanical properties. A possible mechanism for the appearance of transcrystallinity involving crystal structure matching is also proposed. © 1993 John Wiley & Sons, Inc.
Modification of epoxy surfaces with different polyvinylalcohol polymers
Authors: Chihani T. , Flodin P. , Hjertberg T.
Published: April 2003

An epoxy resin, consisting of diglycidylether of bisphenol A (DGEBA) and methyltetrahydrophtalic anhydride (MTHPA), was cured against peel‐plies coated with different poly(vinylalcohol‐co‐vinylacetate) (PVOH). The epoxy polymer surface was characterized with X‐ray photo electron spectroscopy (XPS), contact angle measurements, and scanning electron microscope (SEM). PVOH, which is a water soluble polymer, was detected at the cured epoxy polymer surface with XPS after washing with hot water. The PVOH polymer at the outermost surface has hydroxyl groups, which can react with both the adhesive and the epoxy resin. The modified epoxy composite surfaces were adhesively bonded with a polyurethane and an epoxy adhesive. Improved adhesion was obtained between modified epoxy composite surfaces and different adhesives. © 1993 John Wiley & Sons, Inc.
Effect of glow discharge treatment of poly(acrylic acid) preadsorbed onto poly(ethylene)
Authors: Terlingen Johannes G. A. , Hoffman Allan S. , Feijen Jan
Published: April 2003

In order to introduce carboxylic acid groups at the surface of poly(ethylene) (PE) films, an attempt was made to covalently link a preadsorbed layer of poly(acrylic acid) (PAAc) on a PE film by an argon or tetrafluoromethane (CF4) plasma treatment. Surface analysis was performed by XPS (X‐ray photoelectron spectroscopy) and water contact angle measurements. It was shown that by treatment of a PAAc layer preadsorbed on PE with an argon or a CF4 plasma, a small amount of carboxylic acid groups was introduced at the surface. A similar amount of these groups was obtained by plasma treatment of PE films without a preadsorbed PAAc layer. A comparison of the etching rates of PAAc and PE by either an argon or a CF4 plasma, showed that PAAc is etched much faster by both types of plasmas than PE. The preadsorbed PAAc layer on PE is etched off before it could be immobilized by either an argon or a CF4 plasma treatment. Additionally the effect of treating PE films for very short times with an argon or a CF4 plasma was studied. After an induction period of approximately 0.1 s, the oxidation during the argon plasma treatment and the fluorination during the CF4 plasma treatment were proportional to the logarithm of the treatment time for time periods up to 50 s. © 1993 John Wiley & Sons, Inc.
Effect of reinforcing carbon black filler on thermally induced crosslinking of polyacrylic acid‐epoxidized natural rubber blend
Authors: Mallick A. , Tripathy D. K. , De S. K.
Published: April 2003

That carbon black filler influences the thermally induced crosslinking between polyacrylic acid (PAA) and epoxidized natural rubber (ENR) is evident from Monsanto rheometric studies, dynamic mechanical analyses, and physical property measurements. Considerable shift in glass transition temperature, as well as broadening of the loss peak due to ENR, along with disappearance of the loss peak due to PAA, indicate that HAF carbon black, at 20 parts per 100 of total polymer, make the immiscible PAA/ENR blend behave as a compatible blend. © 1993 John Wiley & Sons, Inc.
Benzoyl‐peroxide‐initiated graft copolymerization of poly(ethylene terephthalate) fibers with acrylic acid
Authors: Sacak Mehmet , Oflaz Fazli
Published: April 2003

The grafting of acrylic acid onto poly(ethylene terephthalate) fibers subjected to a noswelling treatment using benzoyl peroxide was investigated. The temperature was found to increase the graft yield. The grafting yield increased up to a benzoyl peroxide concentration of 4.0 × 10−3 M and slightly decreased at higher initiator concentrations. The effects of solvents such as dimethylformamide, dimethylsulfoxide, pyridine, and some alcohols upon the grafting were examined by carrying out the graft copolymerization at various water/solvent ratios. Pyridine was found to inhibit the grafting totally. The properties of the grafted fibers such as density, diameter, dyeability, and moisture regain were also investigated. It was concluded due to the observations made in these properties that the grafting took place mainly in the subsurface regions of the fibers and there occurred a diffusion barrier after the grafting value of 8–9%. The overall activation energy for grafting was calculated to be 9.9 kcal/mol. © 1993 John Wiley & Sons, Inc.
Infrared spectroscopy studies of the effects of the catalyst on the ester cross‐linking of cellulose by poly(carboxylic acids)
Authors: Yang Charles Q.
Published: April 2003

The esterification of cellulose by a poly(carboxylic acid) proceeds in two steps: the formation of a 5‐membered cyclic anhydride intermediate by the dehydration of two carboxyls, and the reaction between cellulose and the anhydride intermediate to form an ester. Sodium hypophosphite is the most effective catalyst for the esterification. The effect of sodium hypophosphite on the esterification of cotton cellulose was studied by Fourier transform infrared spectroscopy (FTIR). It was found that sodium hypophosphite accelerates both the formation of the cyclic anhydride intermediate and the reaction between the anhydride intermediate and cellulose. The chief role of sodium hypophosphite is possibly the acceleration of the esterification of cellulose by the anhydride intermediate. © 1993 John Wiley & Sons, Inc.
Crystallization kinetics of high‐density polyethylene/linear low‐density polyethylene blend
Authors: Gupta A. K. , Rana S. K. , Deopura B. L.
Published: April 2003

This article presents crystallization kinetics studies on a cocrystallizing polymer highdensity polyethylene (HDPE)/linear lowd‐ensity polyethylene (LLDPE) blend. The nonisothermal crystallization exotherms obtained by differential scanning calorimetry (DSC) were analyzed to investigate the effect of cocrystallization on kinetics parameters, namely the Avrami exponent and activation energy. The regular change of Avrami exponent with blend composition from a value of about 3 corresponding to HDPE to a value of 2 corresponding to LLDPE is observed. A sheaf‐like crystalline growth with variation of nucleation depending on blend composition is concluded from these results of DSC exotherm analysis in conjunction with the small‐angle light scattering observations. The observed variation of activation energy of crystallization with blend composition suggests the role of interaction of side chains and comonomer units present in the LLDPE. © 1994 John Wiley & Sons, Inc.
Syntheses and cured films properties of UV‐autocurable BTDA‐based multiacrylate resins
Authors: Chiang Wen‐Yen , Lin Wen‐Tser
Published: April 2003

A series of UV‐autocurable 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and benzophenone tetracarboxylic acid (BTAc)‐based multiacrylate resins containing pendant glycidyl methacrylate (GMA) or glycidyl acrylate (GA) and 2‐hydroxyethyl acrylate (HEA) or 2‐hydroxyethyl methacrylate (HEMA) were synthesized. The effects of the acrylic functional groups, the moles of GMA, and the molar ratio of HEMA/HEA on their properties were investigated. The prepared autocurable resins are cured rapidly when exposed to UV or sunlight radiation without addition of any photoinitiator or Photosensitizer and the acrylate‐type resin resulted in a lower thermal curing temperature and a fast curing rate. Increasing the moles of GMA or the molar ratio of HEMA/HEA on reaction leads to a higher cross‐linking density and resulted in film with a higher Young's modulus, breaking strength, and lower elongation. The methacrylate‐type resin cured to a very hard, but brittle film with a higher Young's modulus and lower elongation. However, the acrylate‐type resin cured to a hard tough film with a lower Young's modulus and higher elongation. The cured methacrylate‐type resin results in a lower weight loss at temperature below 300°C due to a higher cross‐linking density and lower residual weight percent at 600°C due to the lower percent of benzene rings in the resin. The film properties of the resins coated on steel plates were also investigated. © 1994 John Wiley & Sons, Inc.
DNA‐like and phospholipid‐like phosphorylated polystyrenes: Characterization, distribution of functional groups, and calcium complexation properties
Authors: Imbert E. , Souirti A. , Menard V. , Pfluger F. , Jozefowicz M. , Migonney V.
Published: April 2003

The phosphorylation of cross‐linked polystyrene resins has been previously described. As seen by their interaction with lupus antibodies, these polymers were found to mimic either DNA or phospholipid antigens, depending on the degree of substitution by phosphate groups. When an alkyl spacer was included between phosphate groups and macromolecular chains, difficulties in synthesis and desorption of the biological species from the resins were seen. In this article, kinetic aspects of the synthesis of phosphorylated polymers, possessing sulfamide spacers, are discussed. The characterization of these phosphorylated polymers by acidimetric titration is extensively described. This technique differentiates and quantifies the grafted phosphate groups, which can be either phosphomonoester or phosphodiester in nature. We demonstrate that these polymers form complexes with calcium ions, and that the affinity of the ions is closely associated with the type of phosphate groups. © 1994 John Wiley & Sons, Inc.
Interfacial effects produced by crystallization of polypropylene with polypropylene‐g‐maleic anhydride compatibilitzers
Authors: Duvall J. , Sellitti C. , Myers C. , Hiltner A. , Baer E.
Published: April 2003

Two anydride‐grafted isotactic polypropylene (PP) compatibilizers, HAC or high‐anydride compatibilizer (2.7 wt % grafted maleic anhydride) and LAC or low‐anydride compatibilizer (0.2 wt % anydride), were compared in PP‐rich blends with polyamide‐66 (25 wt %). A previous article demonstrated that LAC imparted a much higher fracture strain than did HAC at similar anydride concentrations. The present study shows that LAC is capable of cocrystallization with PP. HAC does not cocrystallize, but crystallizes as a second phase in binary PP/HAC blends studied by DSC and hot‐stage microscopy. A cocrystallization model is proposed to explain the higher fracture strain of PP/LAC/PA blends. A. separate phase crystallization model is proposed for PP/HAC/PA blends. The models are supported by peel tests, which demonstrate greater adhesion of PP with LAC than with HAC. © 1994 John Wiley & Sons, Inc.
Acetals as nucleating agents for polypropylene
Authors: Smith Tammy L. , Masilamani Divakaran , Bui Long Kim , Brambilla Raymond , Khanna Yash P. , Garbriel Kristina A.
Published: April 2003

Nucleating agents increase the impact strength, tensile strength, and tensile elasticity modulus of semicrystalline polymers. Nucleating agents also decrease product cycle times, resulting in a cost savings per product unit. We have synthesized and tested 15 compounds as nucleactors for polypropylene. Of these, trinapthylidene sorbitol, tri‐(4‐methyl‐1‐naphthylidene)sorbitol, tri‐(4‐methoxy‐1‐naphthylidene) sorbitol, and dibenzylidene xylitol are efficient nucleators of polypropylene. Trinaphthylidene sorbitol (tns) has two major diastereomers: The “S” diastereomer yields a faster crystallization rate for polypropylene than does the commercial nucleator dibenzylidene sorbitol (Millad 3905). Crystallization rates are 208 and 88, respectively (t min−1 × 1000). The “R” diastereomer, however, is a poor nucleator and interferes with the nucleating activity of the “S” diastereomer. A 52/48 mixture of diastereomers does not nucleate polypropylene, even at twice the concentration. This is first time that the importance of stereochemistry has been demonstrated in the nucleating action. © 1994 John Wiley & Sons, Inc.
Behavior of amine‐modified urea–formaldehyde‐bonded wood joints at low formaldehyde/urea molar ratios
Authors: Ebewele Robert O. , River Bryan H. , Myers George E.
Published: April 2003

Urea–formaldehyde‐bonded wood products are limited to interior nonstructural applications because of their poor durability under cyclic moisture or humid environments. The stability of solid‐wood joints and particleboards can be enhanced by bonding with urea–formaldehyde adhesives modified with di‐ and trifunctional amines at an effective resin formaldehyde‐to‐urea mol ratio (F/U) of 1.6; however, particleboard formaldehyde emissions were not improved over those from boards made with unmodified adhesives and were unacceptably high. The relative effectiveness of selected modifications was investigated at resin form aldehyde‐to‐urea (F/U) molar ratios of 1.4 and 1.2 Solid‐wood joints and particleboards made with modified adhesives, an unmodified adhesive, and a phenol formaldehyde (PF) resin were subjected to cyclic soak‐dry (cyclic stress) treatments and moist‐heat aging. Formaldehyde emissions from particleboards were also determined. At F/U 1.4, the resistance of solid‐wood joints made with modified adhesives to cyclic stress and moist‐heat aging was equal to that of PF‐bonded joints and superior to that of joints bonded with unmodified adhesive. The resistance of particleboards made with modified adhesives was greater than that of boards made with unmodified adhesive but less than that of PF‐bonded board. Solid‐wood joints and particleboards made with F/U 1.4 resins performed better than did those made with F/U 1.2 resins. Particleboards made with F/U 1.2 resins had formaldehyde emissions well below the standard, and room temperature aging or bonding at high temperature reduced emissions substantially. © 1994 John Wiley & Sons, Inc.1

This article is a US Government work and, as such, is in the public domain in the United States of America.
Sulfonation of cross‐linked asymmetric membranes based on polystyrene and divinylbenzene
Authors: Byun H. S. , Burford R. P. , Fane A. G.
Published: April 2003

Asymmetric microporous membranes based on polystyrene cross‐linked with divinyl benzene were prepared. They were sulfonated with sulfonic acid and washed with solutions of gradually increasing pH to reduce environmental shock. The sulfonation was monitored by infrared spectroscopy, and changes in wettability and sulfur content were also recorded. Morphologies and reverse osmosis performance of sulfonated membranes were measured, with both water flux and salt rejection increasing after treatment. © 1994 John Wiley & Sons, Inc.
Polypropylene/poly(vinyl acetate) blend fiber
Authors: Xiao Weiwei
Published: April 2003

Polypropylene/poly(vinyl acetate) (PP/PVAc) (30/70) blend possesses higher thermal stability than PVAc and is stable below 300°C. The viscosity of the blend is lower than that of PP and PVAc at 220°C. The blend fibers have sheath‐core morphology; the core is composed of PP fibrils because PP has reasonably higher viscosity than PVAc. Due to the reinforcement of PP fibrils, the tensile strength and modulus of the blend fibers were increased. The blend fibers drawn at 50°C possess better mechanical properties than those drawn at 90°C. © 1994 John Wiley & Sons, Inc.
Pervaporation separation of binary organic–aqueous liquid mixtures using cross‐linked PVA membranes. II. Phenol–water mixtures
Authors: Rhim Ji‐Won , Sohn Min‐Young , Lee Kew‐Ho
Published: April 2003

The pervaporation separation of water‐phenol mixtures was carried out using poly(vinyl alcohol) (PVA) cross‐linked membranes with low molecular weight poly(acrylic acid) (PAA) at 30, 40, and 50°C. The separation was concentrated on the second stage of the water‐selective process at which the phenol concentration could be 80 wt % of phenol. The high separation factor of αw/p, = 3580 for the PVA/PAA = 80/20 membrane was obtained for the phenol : water = 80 : 20 solution at 30°C. © 1994 John Wiley & Sons, Inc.
Attempt to reduce bowing distortion in tentering of film
Authors: Yamada Toshiro , Nonomura Chisato
Published: April 2003

In order to solve the problem of the bowing phenomenon in the tentering process of film, the stretching and thermosetting conditions were examined with a poly(ethylene terephthalate) film. The simulated and experimental results confirmed that decreasing or preventing the transmission to the next thermosetting zone of the longitudinal force generated by the transverse stretching, and then restretching the film in the thermosetting zone, effectively reduces the bowing distortion. The following effects were observed: (1) Once the film is cooled after stretching it in a tenter, the different patterns of its deformation behavior can be obtained. The bowing distortion changes remarkably with the temperature of film and the length of the cooling zone. (2) When the temperature of the cooling zone is not higher than the glass transition point, the effect of the cooling zone in reducing the bowing distortion is at its maximum. The longer the cooling zone is, the less the bowing distortion becomes. However, it becomes almost constant when the length of the cooling zone is at least twice the width of the film. (3) When the cooling zone is set up between the stretching and thermosetting zones, the bowing distortion is almost independent of the thermosetting temperature. (4) Relaxation and restretching in the transverse direction in the thermoseting zone influence the bowing distortion: greater relaxation results in greater bowing distortion and greater restretching results in the less bowing distortion. © 1994 John Wiley & Sons, Inc.
Electrically conductive composite of polypyrrole and liquid crystalline copoly(ester‐amide)s
Authors: Bao Jingsheng , Xu Chaochou , Cai Wei , Bi Xian‐Tong
Published: April 2003

The modification of the mechanical properties of polypyrrole (PPY) by electrochemical preparation of conductive composite film from pyrrole (PY) and three kinds of liquid crystalline copoly(ester‐amide)—PEA(H), PEA(C), PEA(O)—are presented. The electrical conductivity of the PEA(H)/PPY, PEA(C)/PPY, and PEA(O)/PPY composites are the same order of magnitude as PPY. The mechanical properties of the composite films are much better than that of pure PPY, and the composite films have good conductivity and thermostability. © 1994 John Wiley & Sons, Inc.
Thermochemical stress crazing and cracking of thermoplastics
Authors: Legrand D. G.
Published: April 2003

A new method of inducing crazing and cracking in thermoplastics is discussed. The method involves the thermal quenching of hot thermoplastics into simple organic liquids or organic solutions. Data are presented for several different thermoplastics and a number of different liquids. The results are interpreted in terms of a model based on the work of Manning and Lineback that incorporates thermal strains and stresses, thermal conductivity, specific interfacial energies, and defects. The specific crazing energy for bisphenol‐A polycarbonate when quenched into isopropyl alcohol is determined to be approximately 3 × 105 erg/cm2 from this model. © 1994 John Wiley & Sons, Inc.
Modification of nylon‐6 with semi‐rigid poly(p‐diphenylmethyl terephthalamide) using MDI as a chain extender
Authors: Lin Ming‐Fung , Shu Yao‐Chi
Published: April 2003

The purpose of this study is to reinforce the flexible nylon‐6 by using Poly(p‐diphenylmethyl terephthalamide) (PMA) using MDI as a chain extender. Observation by scanning election microscopy showed that the multiblock copolymer had a homogeneous texture. From the differential scanning calorimetry measurements, the multiblock copolymers were shown to have only one melting point, Tm, which is higher than that of nylon‐6. The wide‐angle X‐ray diffraction pattern shows that nylon‐6 has two diffraction peaks at 2θ = 20° and 23.8°. However, the multiblock copolymer has only one peak at 2θ = 20°, indicating a different crystal structure of multiblock copolymers. The copolymers appears to have a significant reinforcing effect on the mechanical properties. © 1994 John Wiley & Sons, Inc.
Molecular model for solid‐state polymerization of nylon 6. II. An improved model
Authors: Kulkarni Mukund R. , Gupta Santosh K.
Published: April 2003

An improved mathematical model using the Vrentas–Duda theory for diffusion coefficients is developed for solid‐state polymerization (SSP). This model is applied to nylon 6, and best‐fit values of the parameters are obtained for this system using the Box complex analysis on available experimental data. The sensitivity of results to variations of these parameters is studied. It is found that the ring opening reaction can easily be omitted and the number of parameters thereby decreased. Detailed quantitative results are obtained to study the effects of changing the important operating conditions on SSP, e.g., intermediate remelting of nylon 6 powder, value of the water concentration (or level of vacuum) in the vapor phase, leaching of monomer and water before SSP, size and degree of crystallinity of polymer particles, etc. The diffusional effects on the rate constants are found to depend on a complex interplay of several important factors such as the generation of monomer and water by reaction, removal of water by macro‐level diffusion, changes in the intrinsic rate constants due to decrease in the concentration of polymer molecules, etc. © 1994 John Wiley & Sons, Inc.
Complexation between poly(2‐hydroxypropyl methacrylate) and three tertiary amide polymers
Authors: Dai Jie , Goh S. H. , Lee S. Y. , Slow K. S.
Published: April 2003

The complexation behavior between poly(2‐hydroxypropyl methacrylate) (PHPMA) and three isomeric tertiary amide polymers, namely, poly(N‐methyl‐N‐vinylacetamide) (PMVAc), poly(N,N‐dimethylacrylamide) (PDMA), and poly(2‐ethyl‐2‐oxazoline) (PEOx), was studied. PHPMA forms interpolymer complexes with the three tertiary amide polymers at the entire feed composition range in methyl ethyl ketone and tetrahydrofuran solutions, indicating a strong intermolecular interaction between different polymer chains. However, complexation does not occur between PHPMA and the three tertiary amide polymers in N,N‐dimethylformamide solutions. Infrared spectroscopic studies show that the intermolecular hydrogen bonding association between the hydroxyl groups in PHPMA and the amide carbonyl groups in the tertiary amide polymers is stronger than the self‐association between the hydroxyl groups and the ester carbonyl groups in PHPMA. PHPMA has a stronger complexation ability with these tertiary amide polymers than poly(styrene‐co‐allyl alcohol) and poly(hydroxyether of bisphenol‐A) do. © 1994 John Wiley & Sons, Inc.
Polymeric phosphonium salts as a novel class of cationic biocides. VIII. Synergistic effect on antibacterial activity of polymeric phosphonium and ammonium salts
Authors: Kanazawa Akihiko , Ikeda Tomiki , Endo Takeshi
Published: April 2003

Two types of homopolymers {poly[tributyl(4‐vinylbenzyl)phosphonium chloride] and poly[tributyl(4‐vinylbenzyl)ammonium chloride]} and copolymers, in which the compositional ratio of the phosphonium monomer to the ammonium monomer was altered, were prepared. The antibacterial activities of both the mixtures of the homopolymers in which the mixing ratio was altered and the copolymers containing positively charged phosphorus and nitrogen atoms in a single polymer chain were explored by the viable cell counting method in sterile distilled water. In the mixed system, a significant finding was the presence of an optimal mixing ratio for the antibacterial activity. The mixtures of polymeric phosphonium salt and polymeric ammonium salt clearly showed the synergistic effect on the antibacterial activity. On the other hand, the antibacterial activity of the copolymers with different cationic parts increased monotonously with increasing the phosphonium monomer units in the polymers, namely, the incorporation of two types of active moieties into a single molecule seems to be unfavorable for synergism on the antibacterial activity. © 1994 John Wiley & Sons, Inc.
Preparation and adsorption properties of the chelating fibers containing amino groups
Authors: Lu Yun , Wu Cuixia , Lin Weiping , Tang Liyuan , Zeng Hanmin
Published: April 2003

Four kinds of amino‐group‐containing chelating fibers were prepared by reacting diethylenetriamine, diethanolamine, diethylamine, and aminopyridine, respectively, with a grafted fiber PVA‐g‐GMA containing epoxy groups. The γ‐ray preirradiation initiated graft copolymerization of GMA onto PVA fiber, the functionalization of the grafted fiber PVA‐g‐GMA with amino compounds, and the adsorption properties of the obtained chelating fibers were systematically investigated. It is concluded that with increasing monomer concentration, reaction time, and temperature, the grafting percentage increases significantly. In the functionalization of the grafted fiber, reaction time, temperature, solvent, and amount of amine used greatly influence the reaction. 1,4‐Dioxane is a reasonable solvent for the reaction. The chelating fibers present great adsorption amounts and high adsorption rates for Cu2+ ion and Au3+ ion. Among the chelating fibers, the fiber with diethylenetriamine group is the most reasonable chelating fiber for the adsorption of Cu2+ and Au3+. The chelating fibers present good selectivities for Cu2+ in the solution with Cu2+, Mn2+, Ni2+, Co2+, and Zn2+, while presenting quite high selectivities for Au3+ ion in the solution with Cu2+, Au3+, Zn2+, and Cr3+ ions. The chelating fiber with diethanolamine or diethylamine can reduce the adsorbed Au3+ into metallic gold. © 1994 John Wiley & Sons, Inc.
Epoxy/poly(methyl methacrylate) interpenetrating polymer networks—morphology, mechanical and thermal properties
Authors: Das B. , Chakraborty D. , Hajra A. K. , Sinha S.
Published: April 2003

Full and semi‐IPNs were prepared from epoxy and poly methyl methacrylate (PMMA), by the sequential mode of synthesis and were characterized by measurements of ultimate tensile strength (UTS), elongation at break, modulus, and toughness. Aromatic polyamine adducts and ethylene glycol dimethacrylate were used as the crosslinkers for epoxy and comonomer/crosslinker for methyl methacrylate monomer, respectively. Higher UTS and modulus of the semi‐IPNs over full IPNs were attributed to the higher probability of interpenetration. The weight retention in the thermal decomposition of the IPNs and semi‐IPNs were higher than the epoxy homopolymer. This enhancement was presumably related to the presence of the unzipped methyl methacrylate monomer which acted as radical scavangers in the epoxy degradation. © 1994 John Wiley & Sons, Inc.
Sequence determination of vinyl acetate–methyl acrylate copolymers by NMR spectroscopy
Authors: Brar A. S. , Charan Shiv
Published: April 2003

Vinyl acetate/methyl acrylate (V/M) copolymers were prepared by free‐radical solution polymerization in benzene. Copolymer compositions were obtained from 1H‐NMR spectroscopy. Reactivity ratios for the copolymerization of V with M were calculated using the Kelen‐Tudos (KT) and the nonlinear error in variables (EVM) methods. The reactivity ratios obtained from the KT and EV methods are rV = 0.04 ± 0.03 and rM = 7.28 ± 2.88 and rv = 0.04 ± 0.01 and rM = 7.28 ± 0.37, respectively. The microstructure was obtained in terms of the distribution of V‐ and M‐centered triad sequences from 13C{1H}‐NMR spectra of copolymers. Homonuclear 1H‐2D‐COSY and 2D‐NOESY NMR were used to determine the most probable conformer for the V/M copolymer. The copolymerization behavior of the V/M copolymers as a function of conversion is also reported. © 1994 John Wiley & Sons, Inc.
Reactive diluent effect on properties of UV‐cured films
Authors: Ali K. M. Idriss , Khan Mubarak A. , Zaman M. M. , Hossain M. A.
Published: April 2003

Polymer films were prepared with UV radiation from urethane acrylate oligomer (LR 8739) mixed with a photoinitiator (Irgacur 184) and a number of reactive diluents chosen from monofunctional monomers (such as N‐vinyl pyrrolidone, ethylhexyl acrylate, methoxyethyl acrylate, and hydroxyethyl methacrylate), difunctional monomers (hexane dioldiacrylate, butanediol diacrylate, and tripropylene diacrylate), and a trifunctional monomer (trimethylol propane triacrylate). The optimum concentrations of the photoinitiator, oligomer, and diluents were determined. Various properties of the cured films such as pendulum hardness, gel content, swelling ability, tensile strength, and elongation at break were also determined. The glass transition temperatures (Tg) of the diluents were correlated with tensile properties and those of the film. © 1994 John Wiley & Sons, Inc.