bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical and thermal properties of starch‐filled poly(D,L‐lactic acid)/poly(hydroxy ester ether) biodegradable blends
Authors: Garlotta Donald , Doane William , Shogren Randal , Lawton John , Willett J. L. 
Published: March 2003

AbstractThe mechanical, structural, and thermal properties of injection‐molded composites of granular cornstarch, poly(D,L‐lactic acid) (PDLLA), and poly(hydroxy ester ether) (PHEE) were investigated. These composites had high tensile strengths, ranging from 17 to 66 MPa, at starch loadings of 0–70 wt %. Scanning electron microscopy micrographs of fracture specimens revealed good adhesion between the starch granule and the polymer matrix, as evidenced by broken starch granules. The adhesion of the starch granules to the polymer matrix was the greatest when the matrix PDLLA/PHEE ratios ranged from zero to unity. At a PDLLA/PHEE ratio of less than unity, as the starch content increased in the composites, there was an increase in the tensile strength and modulus, with a concurrent decrease in elongation. The effects of starch on the mechanical properties of starch/PDLLA composites showed that as the starch content of the composite increased, the tensile strength and elongation to break decreased, whereas Young's modulus increased. In contrast, the tensile strength of starch/PHEE composites increased with increasing starch content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1775–1786, 2003
Fracture behavior of carbon fiber reinforced plastics determined by the time–frequency analysis method
Authors: Nam Ki‐Woo , Ahn Seok‐Hwan , Moon Chang‐Kwon 
Published: March 2003

AbstractFourier transform has been used to study the frequency characteristics of a signal. However, based on the Fourier transform and power spectrum alone, it is hard to tell whether or not the frequency content of a signal evolves over time, even though the phase of the Fourier transform relates to time shifting. On the other hand, except for a few special cases, the frequency content of the majority of signals encountered in the real world change with time. Recently, to overcome the problem that Fourier transform is unable to represent a nonstationary signal, time–frequency analysis methods that can simultaneously represent information about the time and frequency of a signal have been developed. In this study, the damage process of cross‐ply carbon fiber reinforced plastics (CFRP) during a monotonic tensile test was characterized by acoustic emission (AE). Different laminated types of CFRP were used to determine the characteristics of the AE signal and frequency. The time–frequency analysis method was found to be useful for the determination of the fracture mechanism in CFRP (such as, matrix cracking, debonding–delamination, and fiber fracture). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1659–1664, 2003
Modified chitosan. I. Optimized cerium ammonium nitrate‐induced synthesis of chitosan‐graft‐polyacrylonitrile
Authors: Pourjavadi A. , Mahdavinia G. R. , Zohuriaan‐Mehr M. J. , Omidian H. 
Published: March 2003

AbstractChitin was extracted from shrimp shells and then deacetylated to obtain chitosan. The degree of deacetylation of the chitosan was determined to be 0.76 using pH‐metric titration. A large number of cyanide functional groups were introduced onto chitosan by grafting with polyacrylonitrile as an efficient way of modification. The graft copolymerization reactions were carried out under argon atmosphere in a homogeneous aqueous phase (containing a small portion of acetic acid) by using ceric ammonium nitrate as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of chitosan and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the influential factors, including temperature and concentrations of the initiator, acrylonitrile monomer (AN), acetic acid, and chitosan. The effect of individual factors was investigated by calculating and monitoring the variations of the grafting parameters [i.e., grafting ratio (Gr), grafting efficiency (Ge), add‐on value (Ad), homopolymer content (Hp), and total conversion (Ct)]. Under optimum conditions, the grafting parameters were achieved as 535, 98, 81, 2, and 102%, respectively. A mechanism for the free‐radical grafting was proposed. As empirical rates of polymerization and graft copolymerization were plotted against [AN] and [Ce4+]1/2, the experimental kinetic data displayed a good match to a reported rate statement. The overall activation energy for the graft copolymerization was determined to be 44.9 kJ/mol. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2048–2054, 2003
Controlled rheology of polypropylene: Modeling of molecular weight distributions
Authors: Asteasuain M. , Sarmoria C. , Brandolin A. 
Published: March 2003

AbstractA mathematical model for the controlled degradation of polypropylene is presented in this article. A previous model of this process was extended to predict the whole molecular weight distribution of the modified resin. Probability generating functions were applied to transform the infinite set of mass balance equations of both polymer and radicals. The integration of the transformed set of equations yielded the probability generating function transforms. These transforms were then inverted with two different inversion algorithms, recovering the molecular weight distributions of the polymer. The model predictions were compared with our experimental data and other information taken from the literature. Good agreement was obtained. The approach presented here is also useful for other polymerization and postpolymerization processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1676–1685, 2003
Relationship between processing, microstructure, and mechanical properties of injection molded thermotropic LCP
Authors: Wang Y. L. , Yue C. Y. , Tam K. C. , Hu X. 
Published: March 2003

AbstractA commercial thermotropic liquid crystalline polymer (LCP), Vectra A950, was injection molded into rectangular sheets of thickness ranging from 1 to 4 mm. By changing the thickness of the mold, the shear rate experienced by the TLCP melt in the mold could be varied. The 1‐mm test sample was highly anisotropic while that with larger thickness (4 mm) was less anisotropic. X‐ray diffraction profile at various depths for each of the test sample corresponded to the degree in the fiber orientation present in the test samples. The anisotropy can be described macroscopically by measuring the tensile strength and modulus in the longitudinal and transverse direction. The ratio between the longitudinal and transverse property decreases proportionally to the thickness of the test sample. This reduction corresponded to the reduction in the shear field as the thickness of the mold was increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1713–1718, 2003
High molecular weight hydrophilic functional copolymers by free‐radical copolymerization of acrylamide and ofN‐acryloylmorpholine withN‐acryloxysuccinimide: Application to the synthesis of a graft copolymer
Authors: D'Agosto F. , Charreyre M.‐T. , Mélis F. , Mandrand B. , Pichot C. 
Published: March 2003

AbstractFree‐radical solution copolymerization of acrylamide (AAm) and of a disubstituted acrylamide derivative,N‐acryloylmorpholine (NAM), with N‐acryloxysuccinimide (NAS) was investigated with the aim to obtain a copolymer of at least 100,000 g mol−1. Different polymerization conditions likely to increase the molecular weight were studied such as monomer and initiator concentrations, temperature, and nature of the solvent. The molecular weights were determined by SEC using a light‐scattering detector. The grafting of end‐functionalized polysaccharide chains onto such high molecular weight poly(NAM‐co‐NAS) was performed and a graft copolymer bearing a high number of saccharidic branches was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1808–1816, 2003
Graft copolymerisation of N‐vinyl pyrrolidone onto polypropylene copolymer in melt: Effect of grafting on thermomechanical properties and paint adhesion
Authors: Srinivasa Rao G. S. , Jain R. C. 
Published: March 2003

AbstractN‐vinyl pyrrolidone (NVP) was grafted onto a polypropylene copolymer (PP) in melt in a Brabender Plasticorder and single screw extruder. The effect of variation of dicumyl peroxide (DCP) and lupersol (LUP) concentrations alone and with 20 wt % NVP concentration in the Brabender Plasticorder on Melt Flow Index (MFI) and final torque values was studied. Variation of NVP concentration (1–10 wt %) at a fixed DCP concentration on percent grafting (G) and MFI was also studied in the single screw extruder. The graft copolymers (PP‐g‐NVP) obtained by reaction of PP with NVP were soxhlet extracted with isopropanol to remove homopolymer, dried, and finally characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The PP‐g‐NVP (0–30 wt %) was used as an additive with PP, extruded in the single screw extruder, molded, and the mechanical properties and paint adhesion was measured. MFI values increased and torque values decreased with an increase in initiator concentration, indicating the dominance of the peroxide‐initiated scission reaction over grafting. DCP gave higher grafting compared to LUP. When NVP concentration was increased, MFI values increased initially due to more scission, and then decreased, indicating more graft copolymer formation. Mechanical properties increased by incorporation of PP‐g‐NVP as an additive than PP‐g‐NVP alone. Paint adhesion increased by the presence of PP‐g‐NVP as additive especially with polyurethane primer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2173–2180, 2003
Plasticization of polymers with supercritical carbon dioxide: Experimental determination of glass‐transition temperatures
Authors: Alessi Paolo , Cortesi Angelo , Kikic Ireneo , Vecchione Febe 
Published: March 2003

AbstractHigh‐pressure partition chromatography, a modification of the inverse gas chromatography technique, is presented as suitable technique for the study of the plasticization effect of carbon dioxide on the following polymers: poly(methyl methacrylate), polystyrene, and bisphenol A–polycarbonate. Polymers in the presence of a compressed gas or a supercritical fluid become plasticized; this means that their glass‐transition temperatures (Tg's) can be lowered by 10s of degrees, which causes changes in their mechanical and physical properties. CO2‐induced plasticization has an important impact on many polymer processing operations in which the Tg depressions of the polymers can be evaluated. The experimental results are discussed and compared with data available from literature for each polymer we considered. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2189–2193, 2003
Thermosensitive and ampholytic hydrogels for salt solution
Authors: Cai Wensheng , Gupta Ram B. 
Published: March 2003

AbstractA series of N‐isopropylacrylamide/[[3‐(methacryloylamino)propyl]dimethy(3‐sulfopropyl)ammonium hydroxide] (NIPAAm/MPSA) copolymer hydrogels were prepared with various compositions. Swelling of the hydrogels in water, aqueous NaCl, KCl, CaCl2, and MgCl2 solutions was studied. NIPAAm/MPSA hydrogels have a higher degree of swelling in water and salt solutions than that of poly(N‐isopropylacrylamide) (PNIPAAm). Also, NIPAAm/MPSA hydrogels are more salt resistant when deswelling in salt solutions. For <7 mol % MPSA, the formed hydrogels retain both temperature reversibility and high swelling. A higher content of MPSA (>11 mol %) leads to better salt resistance but a decrease in thermosensitivity. The swelling of NIPAAm/MPSA hydrogel in 0.05M NaCl is non‐Fickian. In NaCl and KCl aqueous solutions, the zwitterionic hydrogels do not show obvious antipolyelectrolyte swelling behavior, whereas in divalent salt CaCl2 and MgCl2 solutions, the swelling ability of NIPAAm/MPSA hydrogels is enhanced at low salt concentration, then decreases with further increase in salt concentration. The lower critical solution temperatures of NIPAAm/MPSA hydrogels are also affected by concentrated salt solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2032–2037, 2003
Viscoelastic behavior in a hydroxyl‐terminated polybutadiene gum and its highly filled composites: Effect of the type of filler on the relaxation processes
Authors: De La Fuente José L. , Fernández‐García Marta , Cerrada María L. 
Published: March 2003

AbstractInvestigations have been ongoing to learn the rheological and/or mechanical behavior of composite solid propellants based on hydroxyl‐terminated polybutadiene (HTPB). The mechanical properties of these materials are related to the macromolecular structure of the binder as well as to the content and nature of the fillers. The viscoelastic behavior of an HTPB binder and its composites with different types of fillers was surveyed by dynamic mechanical analysis over a wide range of temperatures. This technique has clearly demonstrated a two‐phase morphology developed in these systems. The temperature location, intensity, and apparent activation energy of the distinct relaxations are discussed. The dependency of the relaxation processes on filler content in a series of composites has elucidated the interactions between the filler particles and the existing hard‐ and soft‐segment domains within the polyurethane matrix. It was observed that the nature of the filler significantly affects the relaxation process associated with the hard‐segment domains of the polymeric structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1705–1712, 2003
Radiation crosslinking of poly(butylene succinate) in the presence of low concentrations of trimethallyl isocyanurate and its properties
Authors: Suhartini Meri , Mitomo Hiroshi , Nagasawa Naotsugu , Yoshii Fumio , Kume Tamikazu 
Published: March 2003

AbstractPoly(butylene succinate) (PBS) with different molecular weights was irradiated using an electron beam (EB) in the presence of polyfunctional monomers at ambient temperature. Five polyfunctional monomers were used in this work. The highest amount of gel fraction was achieved when PBS was blended with trimethallyl isocyanurate (TMAIC). The amount of TMAIC introduced strongly influenced the amount of resulting gel. It was determined that the crosslinked PBS sample containing 1% TMAIC had a higher glass‐transition temperature than did the original PBS. It was also observed that the presence of crosslinking bonds in the irradiated PBS greatly improved its heat stability and diminished its ability to biodegradate. Accordingly, it can be concluded that crosslinked PBS in the presence of TMAIC significantly improved its heat resistant properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2238–2246, 2003
Poly(acrylic acid‐co‐vinylsulfonic acid): Synthesis, characterization, and properties as polychelatogen
Authors: Rivas Bernabé L. , Schiappacasse L. Nicolás 
Published: March 2003

AbstractThe synthesis of the water‐soluble poly(acrylic acid‐co‐vinylsulfonic acid) at different feed monomer ratios, while maintaining constant the total number of mol, was carried out by radical polymerization. The copolymers were characterized by FTIR and 1H‐NMR spectroscopies. The copolymer composition was determined by its sulfur content and by potentiometric titration. The metal ion binding properties for Ni(II) and Cu(II) in the aqueous phase were studied using the liquid‐phase polymer‐based retention (LPR) technique for two values of ionic strength. For comparison, the retention properties of both homopolymers were included. The complexing ability of the polymer was determined by the relative amount of carboxylic acid groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1698–1704, 2003
Kinetics of slurry phase polymerization of styrene to syndiotactic polystyrene with pentamethyl cyclopentadienyl titanium trimethoxide and methyl aluminoxane. I. Reaction rate analysis
Authors: Choi Kyu Yong , Chung Jin Suk , Woo Boo Gon , Hong Moo Ho 
Published: March 2003

AbstractThe kinetics of syndiospecific slurry polymerization of styrene in heptane has been investigated with pentamethyl cyclopentadienyl titanium trimethoxide [Cp∗︁Ti(OMe)3] catalyst with methylalmuninoxane. The experimental studies at different styrene/heptane ratios indicate that no global gelation occurs at low styrene/heptane ratios even at high styrene conversion. The effective propagation rate constant tends to decrease as polymerization rate is increased at higher initial styrene concentrations. To analyze the effect of catalyst deactivation, a novel three‐stage polymerization experiment has been designed and carried out where monomer is added during the polymerization. The experimental results show that the catalyst activity is very high at the beginning of polymerization but it decreases significantly as catalyst sites are occluded in the solid phase. We also observe that the catalyst remains active for more than 3 h and the rate decay is not solely due to intrinsic catalyst deactivation. Our experimental data suggests that physical transport effects cause the decay in the polymerization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2132–2137, 2003
Photoresponse gas permeability of azobenzene‐functionalized glassy polymer films
Authors: Kameda Mitsuyoshi , Sumaru Kimio , Kanamori Toshiyuki , Shinbo Toshio 
Published: March 2003

AbstractThe gas permeability of membranes composed of a polymer functionalized with azobenzene chromophores (azopolymer) was investigated under different conditions of light irradiation. A series of measurements with He gas showed that the permeability of the membranes increased by 5–10% upon irradiation with blue light, which caused cyclic photoisomerization of the azobenzene chromophores. In contrast, no significant change in gas permeability and no photoisomerization of the azobenzene chromophores were observed upon irradiation with red light. Moreover, using a digital video microscope, we observed that azopolymer irradiated with blue light spread out from localized particulate domains and thinly covered the surface of the base membrane. Together with the results of the photoresponse permeability measurements, this observation strongly suggested the existence of photoinduced plasticization as discussed in the study of photoinduced surface relief formation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2068–2072, 2003
Preparation of SBS/poly(styrene–methyl methacrylate) thermoplastic interpenetrating polymer network
Authors: Liao Mingyi , Li Keke 
Published: March 2003

AbstractSBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular‐weight‐distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003
Free‐radical copolymerization of [(4‐isopropyl phenyl) oxycarbonyl] methyl methacrylate with acrylonitrile and methyl methacrylate
Authors: Soykan Cengiz , Erol İbrahim 
Published: March 2003

AbstractResults of investigations on the synthesis and characterization of free‐radical copolymerization of [(4‐isopropylphenyl) oxycarbonyl] methyl methacrylate (IPPOMMA), monomer (M2) with acrylonitrile (AN), and methyl methacrylate (MMA), monomers (M1) in CHCI3 solution at 60°C with AIBN as initiator are presented. Fourier transform infrared, 1H‐NMR, and elemental analyses techniques were used to identify of polymers. Reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdös and Fineman–Ross linearization methods, yielding rAN = 0.60 plusmn; 0.14 and rIPPOMMA = 0.94 ± 0.28 for the AN/IPPOMMA system; rMMA = 0.76 plusmn; 0.30 and rIPPOMMA = 1.08 plusmn; 0.52 for the MMA/IPPOMMA system. The thermal properties of the polymers were studied by thermogravimetric analysis and differential scanning calorimetry. In addition, solubility parameters, inherent viscosities, and densities of polymers were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2331–2338, 2003
Compatibilizing effect of different anhydrides on cane bagasse pith and melamine–formaldehyde‐resin composites
Authors: Mishra S. , Patil Y. P. 
Published: March 2003

AbstractMelamine–formaldehyde‐resin‐based wood–polymer composites were prepared with cane bagasse pith as a filler. The filler was treated with 1% maleic, phthalic, and succinic anhydrides in xylene separately. The treatment was carried out for different time periods. The effects of the treatment were determined from the acid and ester values of the filler material after every treatment time. Therefore, treated and untreated filler materials (60 wt %) were separately employed for the composite preparation with melamine–formaldehyde as a matrix (40%). Various mechanical tests of the prepared composites showed the effect of the treatment. The mechanical properties were improved by the anhydride treatments up to a particular period of the treatment. Each of the anhydrides had a profound effect on the peculiar mechanical properties. Of the three anhydrides, succinic anhydride and phthalic anhydride appeared to be better compatibilizers for a treatment period of 2 h at a concentration of 1% in xylene. The inconsistency in the acid values and mechanical properties beyond 2 h of treatment with the anhydrides was due to chemisorption and desorption phenomena. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1768–1774, 2003
Serotonin in the rabbit ileum: Localization, uptake, and effect on motility
Authors: Dénes Viktória , Lázár Zsófia , Barthó Loránd , Gábriel Robert 
Published: March 2003

AbstractRepeated experiments to localise serotonin in the myenteric plexus of rabbit ileum failed. After preincubation in serotonin (10−5 M), an extensive varicose fibre system was detected by immunocytochemical methods. Stained fibres left the myenteric plexus and ran to the muscle layers. Labelled cell bodies could not be found, even after pretreatment with colchicine or pargyline. Application of reserpine (10−5 M) and fluoxetine (10−5 M) prevented serotonin uptake. Antisera against tryptophan hydroxylase revealed a rich fibre system, including those processes that entered the tertiary plexus. These fibres were able to accumulate serotonin, but again the cell bodies could not be detected. Serotonin caused concentration‐dependent contraction in the longitudinal muscle layer of the rabbit ileum. Pretreatment with tetrodotoxin strongly reduced the effect of serotonin. Preapplication of atropine caused a slight decrease of response evoked by serotonin. Combined administration of tetrodotoxin and atropine significantly reduced the responses to serotonin, but did not abolish them. At the same time, agonists of 5‐HT2 and 5‐HT4 receptors caused concentration‐dependent contractions. Our studies show that: 1) Without pretreatment, serotonin cannot be detected in the myenteric plexus of rabbit ileum. 2) An extensive uptake system works in this plexus. If released from myenteric nerve fibres, serotonin may evoke contractions in indirect and direct ways. 3) There may be an extrinsic serotoninergic innervation from the mesenteric ganglia. 4) Serotonin exerts its effect through 5‐HT2 and 5‐HT4 receptors on smooth muscle cells and nerve elements. Anat Rec Part A 271A:368–376, 2003. © 2003 Wiley‐Liss, Inc.