bluuebunny/crossref_metadata_2025 huggingface dataset:
Partially miscible blends of epoxy resin and epoxidized rubber: Structural characterization of the epoxidized rubber and mechanical properties of the blends
Authors: Bussi Philippe , Ishida Hatsuo
Published: April 2003

The cure process and the mechanical properties of blends of diglycidyl ether of bisphenol‐A–based epoxy resin and hydroxyl terminated, internally epoxidized polybutadiene rubber have been studied. Internal oxirane groups are characterized by a main absorption at 885 cm−1 in the infrared spectrum while the terminal oxirane groups of the diepoxide monomer absorb at 913 cm−1. In the absence of prereaction of the rubber, gelation of the epoxy matrix occurs much faster than any reaction involving the internal oxirane groups or the terminal hydroxyl groups. Therefore, only weak chemical bonding between the rubber particles and the epoxy matrix exists and the fracture toughness of the blends does not show any significant improvement. Upon prereaction of the rubber with an excess diepoxide monomers, a 40% improvement in the value of the critical stress intensity factor is obtained. However, dynamic mechanical spectra of these blends acquired in the rubbery plateau region uniquely demonstrate that this improvement is due to the incorporation of the rubber into the epoxy network rather than to the presence of phase‐separated rubber particles. © 1994 John Wiley & Sons, Inc.
Structural characterization of Celgard® microporous membrane precursors: Melt‐extruded polyethylene films
Authors: Chen R. T. , Saw C. K. , Jamieson M. G. , Aversa T. R. , Callahan R. W.
Published: April 2003

“Row nucleated lamellar” structures are formed when highly crystalline polymers are melt‐extruded and recrystallized under high stress. Polyethylene (PE) and polypropylene (PP) films with row lamellar structures have been utilized to produce microporous membranes. Birefringence measurements of melt‐extruded PE films show that improved film orientation can be achieved by annealing, extruding at higher speed, and using higher molecular weight polymers. Images from scanning tunneling, atomic force, and field emission scanning electron microscopy (STM, AFM, and FESEM) clearly show the lamellar structures in the melt‐extruded PE and PP films. Microscopy results also show that surface lamellar textures are more pronounced with thicker lamellae and are better aligned along the extrusion direction after annealing. X‐ray diffraction results show that the increase in film orientation can be attributed to increased lamellar perfection and orientation during annealing and also to better crystallite alignment along the machine direction with higher extrusion speed or with higher molecular weight. High‐resolution capabilities of STM, AFM, and FESEM prove to be very effective tools in elucidating lamellar structures in polymeric membrane precursors and can be used as an aid in establishing structure–process–property relationships in making microporous membranes. © 1994 John Wiley & Sons, Inc.
Rigid rod polyamides based on 2,2′,6,6′‐tetrasubstituted biphenyls: Synthesis, characterization, and structures
Authors: He C. , Griffin A. C. , Windle A. H.
Published: April 2003

Polyamides based on 4,4′‐diamino‐2,2′,6,6′‐tetrasubstituted biphenyls and phenylterephthalic acid have been synthesized, and the structures and properties of this series of polymer have been studied. It is shown that the polymers have an amorphous structure although some degree of short‐range order is present. This class of polymer, while consisting of comparatively stiff rodlike molecules, demonstrates high solubility and low glass transition temperatures. The behavior is due to the combination of the noncoplanar conformation of the twisted biphenyl and the fact that they have bulky side groups in the 2,2′‐ and 6,6′‐positions that weaken the interchain interactions (like hydrogen bonding and van der Waals forces) and frustrate parallel packing of the polymer chains. © 1994 John Wiley & Sons, Inc.
Kinetics of reaction of C36 dimer acids with diethylenetriamine and triethylenetetramine for reactive polyamides
Authors: Kale Vijay , Vedanayagam H. Sumathi , Subbarao R. , Rao M. Bhagawant
Published: April 2003

Kinetic studies were carried out on the reaction between C36 dimer acids and diethylenetriamine (DETA) and triethylenetetramine (TETA) in melt phase. The reactions were performed at temperatures in the range of 145°C to 190°C and followed by determination of the acid and amine values of the intermittent products. The polyamidation reactions of C36 dimer acids and DETA and TETA followed overall second‐order kinetics and had activation energies of 14.4 kcal/g mol and 12.3 kcal/g mol, respectively. © 1994 John Wiley & Sons, Inc.
Facilitated permeation of myoglobin through porous membranes: Different permeation behavior through membranes of polyoxyethylene‐ and dextran‐conjugated polyamides prepared by quasi‐living polymerization of a bicyclic lactam
Authors: Hashimoto Kazuhiko , Sugata Tohru , Mashita Atsushi , Okada Masahiko
Published: April 2003

In the ultrafiltration test of a myoglobin solution through porous membranes of the ABA‐type block copolymers composed of polyamide as outer segments and polyoxyethylene (Mn = 1.9–2.0 × 104) as an inner segment, in which the values of weight fraction of the polyamide segments (W) were 0.90, 0.84, 0.82, 0.81, and 0.73, the concentration of the permeate was found to be much higher than that in feed under the pressure difference of 1–2 kg/cm2. Such singularly facilitated permeation was observed also in the test through the dense membranes of the polyamide–polyoxyethylene block copolymer with W of 0.81 and 0.73. On the other hand, neither porous nor dense membranes of the graft copolymer (W = 0.83) having a dextran stock (Mn = 1.8 × 104) and 2.6 pieces of polyamide branches showed similar facilitated permeation, although dextran was soluble in water as well as polyoxyethylene. The apparent interaction of myoglobin with dextran may be stronger than that with polyoxyethylene. © 1994 John Wiley & Sons, Inc.
Generation and structure–property behavior of novel liquid crystalline foams produced via a gas supersaturation technique
Authors: Risch Brian G. , Wan I‐Yuan , McGrath James E. , Wilkes Garth L.
Published: April 2003

Linear and star‐branched polyoxybenzoate–polyoxyphenoxybenzoate copolymers (POB‐co‐POPB) at a 65/35 molar ratio were synthesized via melt acidolysis using AB‐type monomers and branching agents. By controlling the molecular weight and topology of these polymers, both melt processability and solid‐state CO2gas absorption behavior were enhanced. POB–POPB copolymers with a molar ratio 65/35 showed a glass transition of 143°C and completion of melting at ca. 300°C. POB–POBP copolymers with a systematically increasing branching agent content showed a systematically decreasing peak intensity in wide‐angle X‐ray diffraction, indicating that increasing branch‐point concentration leads to a decrease in liquid‐crystal ordering. Star‐branched POB–POPB copolymers showed greatly enhanced carbon dioxide gas absorption behavior relative to their linear counterparts. Whereas CO2blown foams of linear POB‐co‐POPB produced by the gas supersaturation technique had a relatively high density and showed highly anisotropic bubble growth, well‐defined, nearly isotropic foams of star‐branched POB‐co‐POPB with a mean cell size from 200 to 400 μ were made using the gas supersaturation technique. Structural features were characterized via scanning electron microscopy, and mechanical properties were determined by indentation testing with a 0.25 in. ball indenter. These LCP foams exhibit relative mechanical properties similar to polystyrene and microcellular polycarbonate foams. A strong inverse relationship was noted between cell size and modulus for liquid crystalline foams with a cell size below 400 μm. © 1994 John Wiley & Sons, Inc.
High‐energy radiation‐resistant vulcanizates. II. EPDM
Authors: Shah Chaitanya S. , Patni Mahendra J. , Pandya Madhav V.
Published: April 2003

In this article, Part II of the series, we report a detail study on stabilization of EPDM vulcanizates in γ‐radiation environment. The special additives (antirads), namely pyrene (Py), brominated acenaphthene (BrAc), poly(acenaphthene sulfide) (PAcSu) and poly(pyrene sulfide) (PPySu) were used for the stabilization studies. The efficiency of these antirads for EPDM had been monitored by the means of electrical resistivity, wide‐angle X‐ray diffraction, and mechanical properties. The stabilization of EPDM to withstand 200 Mrads of γ radiation in air environment is achieved. © 1994 John Wiley & Sons, Inc.
Study of segmented ethylene terephthalate–caprolactone copolymer by differential refractometry and light scattering
Authors: Wu Chi , Ma Dezhu , Luo Xiaolie , Chan Kam Kwong , Woo Ka Fai , So King Lung
Published: April 2003

A segmented ethylene terephthalate (ET)–caprolactone (CL) copolymer was characterized by light scattering in chloroform tetrahydrofuran and butanone. The flexibility of the copolymer chain is comparable with that of typical flexible chains, such as polystyrene. In the process of applying the Bushuk–Benoit light scattering theory to the segmented PET–PCL copolymer, we encountered not only the problem of finding three solvents with different refractive index but also the problem of determining the specific refractive index increments for the PET and PCL segments in the copolymer, i.e., νPET and νPCL. In principle, the approximate values of νPET and νPCL can be obtained from the PET and PCL homopolymers, respectively. In reality, it involves many practical problems, e.g., to find three solvents not only for copolymer but also for the PET and PCL homopolymers. In this study, a different method was used to find both νPET and νPCL, wherein the ν values of at least two segmented PET–PCL copolymers with different PET compositions were used. With νPET, νPCL, and ν, we characterized the absolute molecular weight. Further, we show that the composition of an unknown segmented PET–PCL copolymer can be estimated from νPET, νPCL, and ν. © 1994 John Wiley & Sons, Inc.
Acid‐ and alkali‐catalyzed tannin‐based rigid foams
Authors: Meikleham N. E. , Pizzi A.
Published: April 2003

Acid‐ and alkali‐catalyzed polyflavonoid tannin‐based rigid foams were prepared. These foams have comparable physical and mechanical properties to the synthetic phenolic rigid foam used as a comparative standard. The fluid polymer phase was based on a mimosa tannin‐formaldehyde resin with a minor addition of a fortifier resin. Expansion of the fluid phase was brought about by a physical blowing agent, whereas dimensional stabilization was achieved through cross‐linking at the desired density. In the case of the acid‐catalyzed foam, a heat‐generating agent in the form of furfuryl alcohol was employed. The polymer composition of tannin–formaldehyde/urea–formaldehyde systems as a function of pH was predicted from the respective gel times and rate constants, i.e., above pH 7, the copolymer proportion will tend to 100% and, that at pH 3.4, the polymer blend proportion will tend to a maximum. © 1994 John Wiley & Sons, Inc.
An analytic approach in kinetic modeling of Ziegler–Natta polymerization of butadiene
Authors: Lee Tai‐Yong , Nitirahardjo Singgih , Lee Sunggyu
Published: April 2003

A kinetic modeling study was conducted for the Ziegler–Natta polymerization of butadiene with cobalt octoate/DEAC/water catalyst. The model equations for the single and dual active site models were analytically solved, and the closed‐form expressions for conversion and both number and weight average molecular weights were obtained. The expressions for conversion and number average molecular weight are identical for both models. Also, the expressions of weight average molecular weight are similar for both models, but the expression for the dual active site model includes an additional scalar parameter. The parameter can be regarded as a “correction factor of weight average molecular weight,” which reflects the effect of dual active sites on the polydispersity. Using the expressions, a simple and noniterative kinetic modeling algorithm was established, and the parameter estimates were obtained. The estimated value of the correction factor ranges from 1.2 to 1.5 depending on the experimental data. The modeling results indicate the validity of the dual active site model. © 1994 John Wiley & Sons, Inc.
Influence of substrate material and ion bombardment on plasma‐deposited fluorocarbon thin films
Authors: O'Keefe M. J. , Rigsbee J. M.
Published: April 2003

The influence of substrate material and ion bombardment on fluorocarbon thin films deposited using a C2F6 glow discharge in an rf, parallel plate reactor was investigated. Monitoring of the plasma process by optical emission spectroscopy indicated that the dominant species in the glow discharge was CF2. Studies of bulk polytetrafluoroethylene (PTFE) and plasma‐polymerized fluorocarbon thin‐film samples in an XPS system demonstrated that the formation of non‐CF2 species can be induced by ion bombardment of CF2 molecules. Characterization of the deposited fluorocarbon films by XPS found that the F/C ratio and CFx distribution (0 < x < 3) in the films were dependent on processing conditions. Fluorocarbon films deposited simultaneously onto Al, glass, steel, and PTFE substrates using a C2F6 plasma and a graphite sputter target had measurably different F/C ratios, with the F/C ratio of the films deposited onto the Al substrates consistently lower than the F/C ratios of the films deposited onto the other substrates. When a C2F6 plasma was used without a graphite target, the F/C ratio in the film was constant, but the CFx distribution was different for each of the substrate materials. Analysis of the plasma‐polymerized films by TEM revealed that localized growth of fluorocarbon particles occurred during the initial stages of deposition, consistent with an activated growth mechanism. Differences in the F/C ratio for films deposited onto the various substrate materials were attributed to the interaction of the fluorocarbon plasma with the exposed surface of the substrate prior to complete coverage by the polymeric film. © 1994 John Wiley & Sons, Inc.
Sorption equilibria and diffusion coefficients of ethanol and water in the PVA membranes containing cyclodextrin
Authors: Yamasaki Akihiro , Mizoguchi Kensaku
Published: April 2003

Effects of cyclodextrin (CD) on the pervaporation characteristics for water/ethanol through the PVA/CD membranes (PVA membranes containing β‐CD oligomer) have been investigated in terms of sorption equilibria and diffusion coefficients based on the sorption–diffusion theory. The increase in water selectivity through the pervaporation by CD was due mainly to the changes in the diffusion coefficients by CD, which depended on the feed composition and the cross‐linking time. The water selectivity through the sorption equilibria was not increased by the addition of CD, and the ethanol‐sorption amount was increased by CD. These effects of CD were interpreted by the inclusion strength in the CD cavity and the cross‐linking density of the PVA phase. © 1994 John Wiley & Sons, Inc.
Graft copolymerization of acrylic acid onto caesarweed fibers by cerric ion–toluene redox pair
Authors: Eromosele Ighodalo Clement
Published: April 2003

The graft copolymerization of acrylic acid onto caesarweed fibers in aqueous media by cerric ion–toluene redox pair has been investigated. The percentage graft increased and then decreased with cerric ion concentration ranging from 8.3 to 100.0 × 10−3 M with a peak value of 17%. The effects of toluene, substituted toluenes, acids, and acrylic acid were examined. The percentage graft increased and then decreased with toluene concentration with an optimum value of 53% at 18.0 × 10−4 M toluene. Under identical reaction conditions, the percentage graft after 30 min for the graft polymerization initiated by substituted toluenes are in the order of p‐toluene sulfonic acid > toluene > p‐Xylene ≃ o‐toluidine. Low concentrations of acetic acid were favorable to the graft polymerization. The percentage graft increased linearly with acrylic acid concentration reaching a value of 53% at 1.39 M acrylic acid. The presence of neutral salts had nominal effects on the percentage graft. The effect of temperature was investigated between 20 and 60°C. The percentage graft increased with temperature up to 40°C but showed a negative temperature dependence beyond 40°C. The calculated activation energy was 6.2 kcal mol−1. Characterization of the physical properties of the grafted fibers was also conducted. © 1994 John Wiley & Sons, Inc.
Determination of microphase structure and scale and scale of mixing in poly‐ε‐caprolactone (PCL)/poly(vinyl chloride) (PVC) blend by high‐resolution solid‐state 13C‐NMR spectroscopy with magic angle spinning and cross polarization
Authors: Kwak S.‐Y.
Published: April 2003

High‐resolution solid‐state, pulsed Fourier‐transform (FT) 13C‐nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) and cross polarization (CP) was applied to a mechanical blend of poly‐ε‐caprolactone (PCL) and poly(vinyl chloride) (PVC) with 50/50 weight ratio (%) whose composition results in very complex morphology and phase structure in the solid state. Proton spin‐lattice relaxation times, T1(1H) and T1ρ(1H), were used as a probe to determine the microphase structure, the degree of homogeneity in terms of the domain size, and the state of mixing of the blend. In particular, T1ρ(1H) was shown to be able to distinguish the separated domains at a level of a few nanometers; the scale of mixing was evaluated from the approximation based on spin‐diffusion phenomenon to be ∼ 4.7 nm below which two polymers were partially mixed and above which they were homogeneously mixed. Treatment of the T1ρ(1H) data with two exponential decay functions resulted in a resolution of individual T1ρ(1H) into rigid and mobile components, from which more detailed information on the phase structure and state of mixing were obtained. © 1994 John Wiley & Sons, Inc.
Use of titanate coupling agents in kevlar–phenolic composites
Authors: Menon Nalini , Blum Frank D. , Dharani L. R.
Published: April 2003

Surface modification of Kevlar fibers with titanate coupling agents for improved adhesion of the fiber and resin in Kevla–phenolic composites has been attempted to explore the possibility of enhancement in adhesion and bulk properties of composites for friction materials. Titanate coupling agents were used and flexural properties of the Kevlar–fiber reinforced composites determined. A study of different amounts of the coupling agents at the fiber–matrix interface suggested that 2% by weight of fiber was the optimum amount, in terms of improvement in flexural properties. The composite samples with the coupling agents showed an increase in flexural strength over the untreated samples, with the maximum increase of about 18% over the control. Water‐absorption studies were conducted on Kevlar–phenolic composites treated with organotitanates to detemine the effectiveness of these coupling agents in improving resistance to moisture attack. The treated Kevlar–phenolic composite samples exhibited greater resistance to moisture‐ingress over the untreated samples. The control samples showed a decrease of 17% in flexural strength. The largest decrease in strength was 14% for the treated samples containing coupling agent tetrakis (2‐ethylhexyl) titanate (TYZOR TOT). Recovery in strength on reconditioning was also greater for treated samples over control. A recovery in strength of about 94% was seen for some treated samples. © 1994 John Wiley & Sons, Inc.
Graft‐copolymerization of glycidyl methacrylate onto cotton cellulose
Authors: Shukla S. R. , Athalye A. R.
Published: April 2003

Glycidyl methacrylate was graft‐copolymerized onto cotton cellolose using both photo‐and chemical‐initiation techniques using different initiators. The photoinitiators used were uranyl nitrate, ceric ammonium nitrate, and benzoin ethyl ether, whereas the chemical initiators used were ceric ammonium nitrate and potassium persulfate. Optimization of various parameters of grafting, viz., time, temperature, initiator, and monomer concentrations, was carried out. Ceric ammonium nitrate gave the maximum and almost identical values of graft add‐on, by both grafting techniques, at equivalent cocentration of the monomer. Use of optimized conditions of ceric ammonium nitrate‐photoinitiated grafting for sodium hydroxide‐swollen substrate as well as for grafting baths incorporating acids enhanced the graft level. © 1994 John Wiley & Sons, Inc.
Carbonization of polyimide films: Effect of cold‐drawing and chemical structure
Authors: Takeichi Tsutomu , Takenoshita Hidehiro , Ogura Satoshi , Inagaki Michio
Published: April 2003

Polyimides of various chemical structures were prepared from pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), oxydianiline (ODA), and p‐phenylenediamine (PDA). The cold‐drawn polyimide films were prepared and carbonized. The electrical conductivity of the carbonized films enhanced linearly with the draw ratio. The effect of cold‐drawing on the electrical conductivity is more remarkable with the rigid polyimides such as PMDA/PDA and BPDA/PDA than the flexible polyimides such as PMDA/ODA and BPDA/ODA. The tendency is well in accord with the effect of cold drawing on the improvement of modulus of polyimides. With the rigid polyimides, the higher alignment of polymer chain is supposed to be achieved by the cold‐drawing. © 1994 John Wiley & Sons, Inc.
Effect of zone annealing on LARC‐CPI thermoplastic polyimide
Authors: Teverovsky Justyna B. , Rich David C. , Aihara Yoshihiko , Cebe Peggy
Published: April 2003

Mechanical properties and structure were studied for undrawn and zone‐drawn films of LARC‐CPI thermoplastic polyimide. The dynamic modulus of undrawn glassy material ranged from about 1.8 to 4.3 GPa, depending upon the degree of crystallinity. After zone drawing to draw ratio of 3.6–4.0, the dynamic glassy modulus was increased to a maximum of 9.5 GPa. The highest moduli were attained in samples that were multiply zone‐drawn. The maximum‐achievable draw ratio increased with the maximum drawing temperature, but the semicrystalline nature of the starting material limited the ultimate drawability. For the first time, highly oriented crystalline films were obtained for X‐ray diffraction and preliminary crystal structure analysis. The crystal lattice was fit to the orthorhombic crystal system, and the results indicate that the lattice parameters are a = 8.0 ± 0.2 Å, b = 5.9 ± 0.2 Å, and c = 36.5 ± 0.3 Å. The value of the c‐axis lattice parameter is very close to the fully extended chain length of the monomer repeat unit. © 1994 John Wiley & Sons, Inc.
Preparation and application of porous silk fibroin materials
Authors: Tsukada Masuhiro , Freddi Giuliano , Minoura Norihiko , Allara Giulia
Published: April 2003

This article deals with the preparation and morphological characterization of porous materials obtained by freezing and lyophilizing silk fibroin solutions. When an aqueous silk solution is frozen at different temperatures (−18, −45, and −80°C), the average pore size decreases with lowering of the freezing temperature. Silk fibroin aggregates obtained in these conditions exhibit a sheetlike structure. By lowering the pH from neutrality to 4.01 and 2.65, the morphology of the solid phase changes from a sheet to a fiber structure. The average pore size is smaller at pH 4.01 than is the former value corresponding to the isoelectric point of silk fibroin. The addition of different amounts of methanol to the silk solution results in a sharp fall of the average pore size and hardens the material, as a consequence of the high packing density of the fibroin molecules. Silk fibroin aggregates prepared in these conditions exhibit a typical fibrous structure. A drug‐delivery system was prepared by incorporating acetylsalicyclic acid into a porous silk fibroin carrier, and the kinetics of the drug release was studied. © 1994 John Wiley & Sons, Inc.
Surface characteristics of polymer/small molecule blends
Authors: Champagne France , Li J.‐F. , Schreiber H. P. , Dipaola‐Baranyi G.
Published: April 2003

Inverse gas chromatographic data have been obtained for polystyrene, polycarbonate, and two substituted amines used as additives in the polymers. Surface energies have been determined and evaluations made of acid/base interaction parameters and Flory–Huggins χ values for the surface bounded interphase. It was shown that acid/base considerations are implicated in the miscibility of these polymer/additive systems. Surface energy analyses showed that surface and bulk compositions in blends differed whether or not the blend components were miscible. Composition differences were the result of thermodynamic drives to minimize surface free energy. © 1994 John Wiley & Sons, Inc.
The effect of water lubrication on polymer wear under rolling contact conditions
Authors: Lutton M. D. , Stolarski T. A.
Published: April 2003

The results of studies into the performance of three selected engineering polymers in rolling contact are presented. Both dry and water lubrication conditions were used. The polymers were machined into a cup simulating the outer race in a rolling contact bearing. Ceramic balls were used in order to create corrosion resistant combinations of materials. Post‐test studies were carried out using a scanning electron microscope. On the basis of microscopy examinations the effect of water on the morphology of contact path surfaces was assessed and the abilities of tested polymers to operate in the presence of water in a rolling contact were ranked. © 1994 John Wiley & Sons, Inc.
Ultimate properties of epoxy resins modified with a polysiloxane–polycaprolactone block copolymer
Authors: Könczöl L. , Döll W. , Buchholz U. , Mülhaupt R.
Published: April 2003

Mechanical and fracture mechanics properties of transparent multiphase epoxy resins toughened with various amounts of compatibilized silicone liquid rubbers consisting of polycaprolactone‐block‐poly(dimethylsiloxane)‐block‐polycaprolactone triblock copolymer have been investigated. At silicone liquid rubber contents < 10 wt % significantly improved toughness has been achieved without adversely affecting thermal and mechanical properties. Fractographic and interferometric methods have been applied to study crack propagation in such silicone‐modified resins. © 1994 John Wiley & Sons, Inc.
1H‐NMR investigation of quantitative functionalization of poly(ethylene glycol)s
Authors: Jankoa K. , Kops J.
Published: April 2003

Poly(ethylene glycol)s, with different molecular weights (4,000–20,000) and a monomethoxy‐substituted poly(ethylene glyco) (molecular weight 5,000) have been quantitatively end group functionalized with bromo and amino groups. The bromination was carried out with thionyl bromide in toluene. 1H‐NMR was used for the determination of the degree of substitution by monitoring the characteristic signals for the CH2Br protons in relation to the signals from the remaining hydroxyl groups. Under the conditions used, qualitative substitution was obtained after repeating the bromination reaction. The results were in agreement with elemental analysis. The bromo end group could be quantitatively converted into amino groups by reaction in absolute ethanol with excess of ammonia or ethylenediamine. Also in this case, 1H‐NMR was used to determine the quantitative substitution by the characteristic signals for the aminomethyl protons and the simultaneous disappearnce of the bromomethyl proton signals. © 1994 John Wiley & Sons, Inc.
Blends of polyethylene terephthalate with Co[poly(ethylene terephthalate‐p‐oxybenzoate)] I. Crystallization kinetics by DSC study
Authors: Ou Cheng‐Fang , Lin Chen‐Chong
Published: April 2003

The dynamic and isothermal crystallization behaviors of polyethylene terephthalate (PET) blended with two types of co[poly(ethylene terephthalate‐p‐oxybenzoate)] copolyesters with different compositions, i.e., POB/PET = 20/80 (P28) and POB/PET = 80/20 (P82), has been studied by using differential scanning calorimetry (DSC). Both of these copolyesters in 10 wt % increase crystallization rate of PET in a manner similar to that of a nucleating agent. It is found that sample P28, which is an isotropic copolyester, accelerates the crystallization rate more significantly than that of P82, which is a thermotropic copolyester. The Avrami exponents n and rate constants k of these samples based on DSC studies were obtained in order to discuss the crystallization kinetics of PET accelerated by these copolyesters. The crystallization rate of the blends is also increased by 8 min blending due to the increased uniformity of the copolyester dispersed in the PET matrix. © 1994 John Wiley & Sons, Inc.
Graft copolymers of nylon 6 and polyphenylene oxide: Syntheses and their role in compatibilizing nylon 6/polyphenylene oxide blends
Authors: Lai Yu‐Chin
Published: April 2003

Poly(2,6‐dimethyl‐p‐phenylene) oxides (PPO) grafted with nylon 6 were prepared by first quantitatively brominating the PPO, followed by reacting the brominated products with nylon 6 of different molecular weights. The molecular weights of PPOs were kept intact during bromination. These graft copolymers with well‐defined structures were used as compatibilizers for nylon 6/PPO blends. Some compatibilization phenomena were observed, as indicated by the mechanical properties of the blends. The best compatibilization was achieved when the graft copolymer is most block‐copolymer‐like. © 1994 John Wiley & Sons, Inc.
Polymers from renewable resources. V. Synthesis and characterization of thermosetting resins derived from cashew nut shell liquid (CNSL)–furfural‐substituted aromatic compounds
Authors: Swain S. K. , Sahoo S. , Mohapatra D. K. , Mishra B. K. , Lenka S. , Nayak P. L.
Published: April 2003

A number of resins were synthesized by reacting cardanol, a byproduct of the cashew industry, with furfural and substituted aromatic compounds in the presence of acid and basic catalysts. The resins were characterized by IR and NMR spectra and shown to be selective ion exchangers for certain metal ions. A batch equilibrium method was used for studying the selectivity of the metal ions. The thermal behavior of the resins was also studied. A plausible degradation mechanism is suggested. © 1994 John Wiley & Sons, Inc.
Activated carbon from lignocellulosic biomass‐phenolic resin
Authors: Simitzis Johannis , Sfyrakis Johannis
Published: April 2003

Lignocellulosic biomass of agricultural/industrial by‐products residues was taken after the pressing and extraction of olive‐oil and lignin Klason and a‐cellulose were isolated. Also, phenol‐formaldehyde was polymerized by using an acid catalyst. Various mixtures of lignocellulosic materials and novolac resin were cured with haxamethylenetetramine and then pyrolyzed up to 1000°C. The IR‐Spectrum of the cured material consisted of 20% novolac and 80% cellulose is practically similar to that of 100% cellulose. The corresponding material with lignin Klason instead of cellulose has different IR‐Spectrum compared to that of 100% lignin, because of additional reactions taken place between lignin and novolac under curing conditions. The weight losses, the shrinkages at the end of the pyrolysis, the specific surface area of the carbonaceous materials produced and their adsorption abilities of methylene blue and alizarin yellow from aqueous solutions were determined. The material consisted of 20% novolac and 80% cellulose or 80% lignin, appears as optimum characteristics of production process. The experimental results are also discussed under the aspect of sample shapes that influence the adsorption as well as the electron donor–acceptor (EDA) interactions between the functional groups of dyes and the carbonaceous materials. © 1994 John Wiley & Sons, Inc.
Liquid chromatography of polymer mixtures applying combination of exclusion and full adsorption mechanisms. I. Analysis of polystyrene in its mixture with polymethylmethacrylate single column/single eluent approach
Authors: Janc̆o Miroslav , Prudskova Tatyana , Berek Dus̆an
Published: April 2003

Components of polymer mixtures with different chemical composition can be separated by liquid chromatography by applying appropriate conditions (column packing, eluent, temperature, and pressure) in which just one type of macromolecule is eluted in the size exclusion mode while the other component is fully retained within on column packing. The feasibility of this idea has been demonstrated using the mixtures of polystyrene (PS) plus polymethylmethacrylate (PMMA) with silica gel as the column packing and toluene as an eluent. The PMMA was retained by the silica get at ambient temperature and moderate pressures of several MPa while the PS was eluted by a typical SEC mecahanism. Furthermore, the molar mass distribution of the PS could be determined in one step with the same precision as if injected alone. Surprisingly large amounts of PMMA were trapped within the column prior to its SEc characteristics being influenced. After a series of analyses the column has to be regenerated with a brief flushing with a desorbing liquid, tetrahydrofuran in the system studied. The re‐equilibrization of the column with the initial eluent, toluene, was fast and a new series of analyses could be started soon after the characterization step had seen finished. © 1995 John Wiley & Sons, Inc.
Enzymatic and ultrasonic depolymerization of carboxymethylated β‐1,3‐D‐glucans derived from saccharomyces cerevisiae
Authors: Machová E. , Kogan G. , Alföldi J. , Šotés L. , Šandula J.
Published: April 2003

Enzymatic and ultrasonic degradations of the carboxymethyl derivative of the β‐1,3‐D‐glucan, isolated from the cell walls of baker's yeast Saccharomyces cerevisiae, are described. The samples obtained upon partial depolymerization of the two carboxymethylated glucans with the substitution degree of 0.56 and 0.91 were characterized by the distributions of their molecular weights and 13C‐NMR spectra. © 1995 John Wiley & Sons, Inc.
Morphological studies of late‐stage spinodal decomposition in polystyrene–cyclohexanol system
Authors: Guo Hong‐Fei , Laxminarayan Anand , Caneba Gerard T. , Solc Karel
Published: April 2003

We studied the late‐stage spinodal decomposition of the polystyrene–cyclohexanol system in relation to membrane formation. Phase separation was effected by the removal of thermal energy from the homogeneous polymer solution. The ultimate morphology of the phase‐separated systems has been studied using electron microscopy and has been found to be strongly affected by the quenching time. A shift from a highly interconnected open‐cell structure to a closed‐cell structure has been observed, indicating the transition of the spinodal decomposition from early to late stages. The cell growth in the late stage has been quantitatively analyzed and a power‐law relationship between the cell size and quenching time has been found. The resulting exponent of 0.61 is consistent with literature values from light‐scattering measurements, as well as from theoretical derivations. © 1995 John Wiley & Sons, Inc.
Effect of added salt on properties of aqueous SMP solution
Authors: Zhuang Yinfeng , Zhu Zhongqi , Chao Hong , Yang Baochen
Published: April 2003

Sulfomethylated phenolic resin (SMP) is a drilling mud additive having good fluid loss and dispersion characters and may be resistant to the action of high temperature and high salt frequently encountered in well drilling, especially in deep wells. SMP is one kind of polyelectrolyte. There are dissociable groups (CH2SO−3Na+) along the chain of SMP. The conformations and properties of SMP in solution are affected greatly due to electrostatic attraction and repulsion. From the experimental results of viscosities and fluorescence spectra of polyelectrolyte SMP in pure water and aqueous solutions containing added salt, the effects of added salt on molecular conformations of SMP in aqueous solution and properties of reducing fluid loss of water base drilling mud are discussed. © 1995 John Wiley & Sons, Inc.
Studies on the block copolymerization of D,L‐lactide and poly(ethyle glycol) with aluminium complex catalyst
Authors: Deng X. M. , Xiong C. D. , Cheng L. M. , Huang H. H. , Xu R. P.
Published: April 2003

A series of block copolymers from D,L‐lactide and poly(ethylene glycol) (PEG) with different molecular weight were synthesized by using Al(i‐Bu)3H3PO4H2O as the initiator and identified by 1H‐NMR, GPC, and DSC. The elongation at break of the material increased when PEG was introduced, but the strength of the material decreased. The copolymers degrade more smoothly in vitro than did the PLA homopolymer. © 1995 John Wiley & Sons, Inc.
Microstructural changes in homopolymers and polymer blends induced by elastic strain pulverization
Authors: Ahn Dongchan , Khait Klementina , Petrich Mark A.
Published: April 2003

A novel polymer processing technique known as elastic strain pulverization (ESP) involves the simultaneous effects of high pressure and shear deformation to pulverize polymers. Homopolymers and blends of commercially important postconsumer plastics, including high‐density and low‐density polyethylene (HDPE, LDPE), polypropylene (PP), and poly styrene (PS) are studied by several characterization techniques to determine the effects of ESP on the microstructure. Electron spin resonance spectroscopy confirms that free radicals are generated by the mechanical rupture of main chain carbon bonds during pulverization by ESP. The possibility of these free radicals terminating by heterogeneous combination to form compatibilizing block or graft copolymers in coprocessed polymer blends establishes the potential of ESP in commingled plastics recycling. Differential scanning calorimetry (DSC) and polarized light microscopy of homopolymers and blends indicate that crystalline structure is drastically altered by ESP processing. Spherulite size reduction is also observed in both crystalline/crystalline and crystalline/amorphous blends after ESP. These results are consistent with homogenization that may be due to the formation of compatibilizing copolymers by heterogeneous macroradical combination. © 1995 John Wiley & Sons, Inc.
Frictional properties of polyolefins treated with fluoroelastomer processing aids
Authors: Gang Hong‐Goo , Cuculo John A. , Nam Sehyun , Crater Davis H.
Published: April 2003

A friction measurement system was designed that made possible the measurement of the friction coefficient between a polymer melt and a metal die wall. The shear stresses developed in the capillary rheometer and the friction coefficient measured in the friction measurement system were compared in an attempt to understand the mechanism of fluoroelastomer processing aids (FPA) in the extrusions of polypropylene (PP) and linear low‐density polyethylene (LLDPE). The apparent viscosity drops of LLDPE treated with FPA were larger than those of PP treated with FPA. The friction coefficient drops of LLDPE treated with FPA were also larger than those of PP treated with FPA. High viscosity FPA showed a moderate friction coefficient drop in the actual extrusion of PP even though it showed only a poor effect in the capillary rheometer. The frictional forces were calculated from the friction coefficient measurement made during extrusions of FPA‐treated and untreated samples. © 1995 John Wiley & Sons, Inc.
Epoxy resins based on trimethylolpropane. II. Kinetic and thermodynamic parameters of cure withm‐XDA
Authors: Pellín M. Pazos , Regueira L. Núñez , Quintela A. Lopez , Losada P. Paseiro , Gándara J. Simal , AbuÍn S. Paz
Published: April 2003

A study of cure of an epoxy resin based on trimethilolpropane (TMP) used as supplied and in purified form and m‐xylylenediamine (m‐XDA), as curing agent has been carried out. Thermodynamic functions such as activation energy, activation entropy, activation enthalpy, and free energy of activation were determinated. From kinetic study we have observed that there are two competitive mechanisms; autocatalyzed and n order, with the values of activation energy ranging between 52.9 and 64.6 kJ/mol. The overall order of reaction is found to be 2.5, and the order of reaction with respect to the hydroxyl group is clearly determined and equal to 1. Gelation study was carried out under two conditions: isothermal and adiabatic. From isothermal study we obtained the values of functionality of the resins (approximately two) and the apparent activation energy of the process. The adiabatic study allowed us the determination of the pot‐life taking into account the theoretical model used, with reasonable theoretical/experimental agreements. The importance of n‐order path for this kind of resins (with high OH contents) is well demonstrated through kinetic and thermodynamic parameters. The thermodynamic functions showed themselves as very sensitive parameters for the following and evolution of the reaction. © 1995 John Wiley & Sons, Inc.
Studies on graft copolymerization of acrylonitrile onto jute fiber with permanganate ion initiation system in presence of air
Authors: Sikdar B. , Basak R. K. , Mitra B. C.
Published: April 2003

The graft copolymerization of acrylonitrile with jute using potassium permanganate as the initiator has been studied in the presence of air. To establish reaction conditions for the graft copolymerization of acrylonitrile (AN) onto jute, the effect of different variables such as the residual lignin content of bleached jute (after bleaching with sodium chlorite), initiator concentration, monomer concentration, time of polymerization, reaction temperature, and amount of bleached jute fiber have been studied. As evidence of polymer grafting, some instrumental analyses such as scanning electron microscopy, infrared, and thermogravimetry have been carried out. The extent of grafting of acrylonitrile depends on how much lignin is present on the jute fiber. Percent grafting and grafting efficiency have also been studied. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of (3,4‐Difuryl‐2,5‐dimethyl) phenyl–polyvinyl silicon oils
Authors: Liu Zonglin , Lu Hongfang , Hao Shuxuan , Wen Xiaoyao , Du Zuodong
Published: April 2003

(3,4‐Difuryl‐2,5‐dimethyl)phenyl–polyvinyl silicon oils (DDP–C‐gum) were synthesized by Diels–Alder reaction of polyvinyl silicon oil (C‐gum) with 3,4‐difuryl‐2,5‐dimethylcyclopentadienone (DDCP) in diphenyl ether at reflux temperature under atmospheric pressure. Their structures were characterized by 1H‐NMR, UV, and IR spectra. Properties such as viscosity, refractive index, color, and thermal stability of some DDP–C‐gums were obtained. © 1995 John Wiley & Sons, Inc.
Influence of pyrolysis temperature on the adsorptive properties of adsorbents produced from novolac and biomass
Authors: Sfyrakis J. , Faliagas A. , Simitzis J.
Published: April 2003

Mixtures of novolac resin and olive stone biomass are cured and pyrolyzed at different temperatures to yield carbonaceous adsorbents. The weight losses and the shrinkages taking place in the carbonization process increase up to ca. 600°C. The pyrolysis residues are investigated with respect to their ability to adsorb toluene and cyclohexane from the vapor phase. Toluene is adsorbed on all adsorbents stronger than cyclohexane. The overall diffusion coefficient D of the adsorption process, the specific surface area, and the pore volume of the adsobents are calculated. The adsorptive properties of the products are interpreted taking into account the size and shape of the pores, the polarity of the adsorbate, and the dispersion forces between adsorbent and adsorbate. Slit‐shaped pores, which are characteristic of carbon molecular sieves, are likely to be present in the adsorbents which are pyrolyzed at higher temperatures and particularly at 1000°C. This adsorbent shows the highest adsorption concerning the equilibrium uptake, specific surface area, and pore volume of toluene and cyclohexane. However, the diffusion coefficient D is lower as more micropores are present. © 1995 John Wiley & Sons, Inc.
Matrix–size interactions in epoxy–glass fibers composites in relation to mechanical relaxations and effects of thermal aging
Authors: Mascia L. , Zhang J.
Published: April 2003

A study was carried out to examine the effect of removing the size from the surface of glass fibers in order to determine its role with respect to thermoxidative aging. Dynamic mechanical relaxation data have revealed that mechanical losses were always greater than the calculated upper bound values. The effects of removing the size from the surface glass fibers for epoxy matrix composites were found to be completely different when a fluoroligomer was used to modify the resin. Contrary to the case of the conventional epoxy resin, the characteristics of the composites containing fluoroligomer‐modified resin were found to be insensitive to the removal of the size from the glass fibers surface. The presence of the size on the surface of the fibers provides an interlayer that degrades through the formation of more lightly crosslinked products than the matrix, thereby providing a large increase in dynamic mechanical losses after thermal aging. © 1995 John Wiley & Sons, Inc.
Comparison of Sanchez–Lacombe and SAFT model in predicting solubility of polyethylene in high‐pressure fluids
Authors: Xiong Yan , Kiran Erdogan
Published: April 2003

Sanchez–Lacombe and SAFT (statistical associating fluid theory) models are used to describe phase behavior of polyethylene solutions (Mw = 2,150, 16,400, 108,000, and 420,000, and MwMn = 1.14, 1.16, 1.32, and 2.66, respectively) in n‐pentane and in n‐butane at high pressures. In order to test the predictive capability of the two models, all the predictions were conducted without any adjustment of the binary interaction parameter. Even though both models correctly predict the general trends of the phase envelopes and the LCST (lower critical solution temperature) nature of the systems, SAFT gives predictions that are much closer to the experimental data than the Sanchez–Lacombe model. © 1995 John Wiley & Sons, Inc.
Synthesis of diglicydilesters with alicyclic imide structure and their thermal and tertiary amine catalyzed curing
Authors: Galià M. , Serra A. , Mantecón A. , Cádiz V.
Published: April 2003

The synthesis of new diglycidylester compounds with bicyclo[2.2.2]oct‐7‐ene units was carried out from the previously synthesized diimide‐diacids and epichlorohydrin in excess using BTMA as catalyst. These compounds were characterized by spectroscopic techniques and have been cured either thermally or using 4‐dimethylaminopyridine as tertiary amine catalyst. The study of curing reaction was carried out through thermal analysis of the reaction by differential scanning calorimetry (DSC). The concentration of the tertiary amine affects the reaction mechanism of epoxide curing, but it does not influence the thermal properties of the final product. © 1995 John Wiley & Sons, Inc.
Miscibility behavior of blends of poly(alkyl methacrylate)s with poly(p‐methylstyrene‐co‐methacrylonitrile)
Authors: Chen Junjie , Goh S. H. , Lee S. Y. , Siow K. S.
Published: April 2003

The miscibility behavior of various poly(p‐methylstyrene‐co‐methacrylonitrile) (pMSMAN)/poly(alkyl methacrylate)s blends was studied using differential scanning calorimetry. pMSMAN is miscible with poly(methyl methacrylate), poly(ethyl methacrylate), poly(n‐propyl methacrylate), poly(isopropyl methacrylate), and poly(n‐butyl methacrylate) over certain copolymer composition ranges, but is immiscible with poly(isobutyl methacrylate) and poly(n‐amyl methacrylate). The width of the miscibility window decreases with increasing size of the pendant ester group of the poly(alkyl methacrylate), and is wider than that of the corresponding poly(p‐methylstyrene‐co‐acrylonitrile) blend system. Various segmental interaction parameters are calculated using a binary interaction model. © 1995 John Wiley & Sons, Inc.