bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alkaline protease production by immobilized growing cells of Serratia marcescens with interpolymer complexes of P(TM‐co‐AAm)/PAA
Authors: Wang Hongzuo , Liu Shiyong , Wang Ying 
Published: August 2002

AbstractThe growing cells of Serratia marcescens (SM) were immobilized with the interpolymer complex carrier, which is formed by the cationic polymer, poly(allyltrimethyl ammonium chloride‐co‐acrylamide) [P(TM‐co‐AAm)], and poly(acrylic acid) (PAA). When the association degree of PAA is suitable to the cationic degree of P(TM‐co‐AAm), the effective crosslinking network provides the most favorable circumstances for the cell immobilization. The alkaline protease can be produced by the immobilized SM with high activity. Compared with the free cells, the immobilized SM has higher thermal stability, acid‐base stability, operational stability, and storage stability. Under the optimum immobilizing conditions, not only the living cells of SM but also thermophilic Bacillus firmus (TBF) were immobilized with the complex of P(TM‐co‐AAm)/PAA. The results show the carrier of P(TM‐co‐AAm)/PAA complex to be superior in properties to the usual carriers, such as Na‐alginate and carrageenan. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 178–183, 2002; DOI 10.1002/app.10293
Colon‐specific oral delivery of vitamin B2 from poly(acrylamide‐co‐maleic acid) hydrogels: An in vitro study
Authors: Bajpai S. K. , Bajpai M. , Kalla K. G. 
Published: August 2002

AbstractHydrogels, composed of poly(acrylamide‐co‐maleic acid) were synthesized and the release of vitamin B2 from these gels was studied as a function of the pH of the external media, the initial amount of the drug loaded, and the crosslinking ratio in the polymer matrix. The gels containing 3.8 mg of the drug per gram gel exhibit almost zero‐order release behavior in the external media of pH 7.4 over the time interval of more than their half‐life period (t1/2). The amount of the drug loaded into the hydrogel also affected the dynamic release of the encapsulated drug. As expected, the gels showed a complete swelling‐dependent mechanism, which was further supported by the similar morphology of the swelling and release profiles of the drug‐loaded sample. The hydrophilic nature of the drug riboflavin does not contribute toward the zero‐order release dynamics of the hydrogel system. On the other hand, the swelling osmotic pressure developed between the gels and the external phase, due to loading of the drug by equilibration of the gels in the alkaline drug solution, plays an effective role in governing the swelling and release profiles. Finally, the minimum release of the drug in the swelling media of pH 2.0 and the maximum release with zero‐order kinetics in the medium of pH 7.4 suggest that the proposed drug‐delivery devices have a significant potential to be used as an oral drug‐delivery system for colon‐specific delivery along the gastrointestinal (GI) tract. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1133–1145, 2002; DOI 10.1002/app.10402
Properties of ligno‐cellulose fiber Hildegardia
Authors: Rajulu A.Varada , Rao G. Babu , Rao B. Ravi Prasad , Reddy A. Madhu Sudana , He Jiasong , Zhang Jun 
Published: August 2002

AbstractStudies on some properties such as the density, the degradation temperatures, the morphology and the spectral features of the ligno‐cellulose fiber Hildegardia were carried out in both untreated and alkali treated form. The fibers are found to have good morphology and moderate initial and final degradation temperatures. On alkali treatment, the lignin was found to be eliminated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2216–2221, 2002
Rheological properties of metallocene isotactic polypropylenes
Authors: Fujiyama Mitsuyoshi , Inata Hitoshi 
Published: August 2002

AbstractRheological properties of metallocene‐catalyzed isotactic polypropylenes (MET‐PP) were evaluated in comparison with those of Ziegler–Natta‐catalyzed isotactic polypropylenes (ZN‐PP) and MET‐PP was generally characterized in a rheological aspect. Based on the characterization, various flow processibilities and their effect on the higher order structure and product properties of the processed article were estimated. The capillary flow properties at various temperatures, elongational flow properties, and dynamic viscoelasticities of MET‐PPs and ZN‐PPs with various melt flow indexes (MFIs) were measured. Furthermore, as an example of application of rheological analysis, the selection of proper raw resin and processing conditions in the sheet‐extrusion of MET‐PP was studied. MET‐PP shows the following rheological features due mainly to the narrow molecular weight distribution in comparison with ZN‐PP with equivalent MFI to that of MET‐PP: while the viscosities at low shear rates are lower, those at high shear rates are higher. Although there is little difference in the loss modulusG″ (viscosity), the storage modulusG′ (elasticity) is very (about one decade) lower. The die swell is much smaller. The entrance pressure loss and end correction coefficient are lower. The critical shear rate at which a melt fracture begins to occur is lower. The melt tension, elongational viscosity, and melt flow index ratio are lower. The flow activation energy is slightly lower. The zero‐shear viscosity obeys the 3.4th‐power law independent of catalyst. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2157–2170, 2002
Preparation of silk fibroin and polyallylamine composites
Authors: Arai T. , Wilson D. L. , Kasai N. , Freddi G. , Hayasaka S. , Tsukada M. 
Published: August 2002

AbstractComposite films made of silk fibroin (SF) and polyallylamine (PAA) are prepared that contain various compositional ratios. These materials are analyzed to elucidate the resulting physical properties and to assess their potential toward advanced applications as industrial materials. The composite films are obtained from a SF and PAA binary system by dry casting from aqueous solution. These composite films exhibit excellent processability such as film forming capabilities, and the elongation at break is increased in the wet state. The differential scanning calorimetry (DSC) curves of the composites suggest that a mutual interaction takes place between the SF and PAA. This interaction is believed to occur because the endothermic peak, corresponding to the individual polymer, shifts with increasing SF content. The random coil conformation of the SF is present, regardless of the PAA blending, as confirmed by FTIR and DSC measurements. Additionally, living cells from Antheraea pernyi and Bombyx mori insect tissues are shown to grow effectively on the composite films. Maximum growth levels occur when the cultivation flask is coated with the material in SF/PAA ratios of 75:25 to 25:75. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1963–1970, 2002; DOI 10.1002/app.10491
A novel approach for albumin determination in aqueous media by using temperature‐ and pH‐sensitive N‐isopropylacrylamide‐co‐N‐[3‐(dimethylamino)‐propyl]methacrylamide random copolymers
Authors: Tuncel A. , Demirgöz D. , Patir S. , Piskin E. 
Published: August 2002

AbstractRandom copolymers of N‐isopropylacrylamide (NIPA) and N‐[3‐(dimethylamino)propyl]methacrylamide (DMAPM) were synthesized by solution polymerization using azobisizobutyronitrile as the initiator in 1,4‐dioxane at 60°C. NIPA‐co‐DMAPM copolymer exhibited both temperature and pH sensitivity. Thermally reversible phase transitions were observed both in the acidic and the alkaline pH regions for copolymers produced with different DMAPM/NIPA feed ratios. The pH dependency of the lower critical solution temperature (LCST) was stronger for copolymers produced with higher DMAPM feed concentrations. NIPA‐co‐DMAPM random copolymer was also sensitive to the albumin concentration. In the presence of albumin, thermally irreversible phase transitions were observed in slightly acidic and neutral media. However, reversible transitions were obtained in aqueous media containing albumin at basic pH. The phase‐transition temperature of NIPA‐co‐DMAPM copolymer significantly decreased with increasing albumin concentration at both acidic and alkaline pH values. This behavior was explained by albumin binding onto the copolymer chains by means of H‐bond formation between the dimethylamino groups of the copolymer and the carboxyl groups of albumin. For a certain range of albumin concentration, the phase‐transition temperature exhibited a linear decrease with increasing albumin concentration. By utilizing this behavior, a simple albumin assay was developed. The results indicated that NIPA‐co‐DMAPM copolymer could be utilized as a new reagent for the determination of albumin concentration in the aqueous medium. The proposed method was valid for the albumin concentration range of 0–4000 μg/mL. The protein concentrations commonly utilized in biotechnological studies fall in the range of the proposed method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2060–2071, 2002; DOI 10.1002/app.10503
Analysis of the effects of the polymerization route of ethylene‐propylene‐diene rubbers (EPDM) on the properties of polypropylene‐EPDM blends
Authors: López‐Manchado Miguel A. , Kenny José M. 
Published: August 2002

AbstractA comparative study of two ethylene‐propylene‐diene rubbers (EPDM) polymerized by both conventional (Ziegler–Natta catalysts) and new techniques (metallocene catalysts) is presented. For this purpose, thermoplastic elastomers based on isotactic polypropylene (iPP) and EPDM blends at different percentages were prepared and their properties examined. In particular, the processing behavior and mechanical properties are reported. So, the flow properties analyzed by torque value, melt index, and rheological study reveal that the blends containing EPDM synthesized by metallocene catalyst present a smaller viscosity, thus offering better processing behavior. On the other hand, the mechanical properties show that metallocene EPDM rubbers give rise to more elastic materials with a higher deformation at break and resilience as well as a lower compression set. Moreover, the effectiveness of these innovative EPDM rubbers as impact modifiers for PP is demonstrated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 25–37, 2002
Water‐soluble acrylamide copolymers. X. Flocculation efficiencies of poly[acrylamide‐co‐N,N‐dimethylacrylamide], poly[acrylamide‐co‐methacrylamide], poly[acrylamide‐co‐N‐t‐butylacrylamide], and their cationic derivatives
Authors: Hocking Martin B. , Klimchuk Keith A. , Lowen Stephen 
Published: August 2002

AbstractA hydrated, 1% by weight Na‐kaolinite suspension in deionized water was prepared, completely characterized, and reproducible measures of flocculation efficiency were validated. Flocculation tests of copolymers of acrylamide (AM) with dimethylacrylamide (DMA), methacrylamide (MeAM), or N‐t‐butylacrylamide (NTBAM) with 1% Na‐kaolinite suspensions gave average settling rate rates which decreased as the proportion of DMA, MeAM, or NTBAM in the copolymer increased. However, for a similar weight‐average molecular weight and slightly lower 〈rg〉, the copolymer from DMA‐co‐AM‐3 gave settling rates and supernatant turbidities comparable to similar types of commercial polymers. This new copolymer was also more resistant to changes in pH or the presence of an electrolyte than were the tested commercial polymers. Cationic derivatives of the new copolymers gave lower average settling rates and higher supernatant turbidities than those of Percol 721 (cationic PAM), probably because of their lower charge densities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2090–2108, 2002; DOI 10.1002/app.10562
Improvement of conductive network quality in carbon black‐filled polymer blends
Authors: Hou Yan Hui , Zhang Ming Qiu , Rong Min Zhi , Yu Gang , Zeng Han Min 
Published: August 2002

AbstractHeat treatment of polymer‐based composites is critical for the enhancement of both stability and long‐term service life, especially when the materials function under an inconstant temperature environment. The present article discusses the effect of heat‐treatment conditions on the electrically conductive properties of carbon black (CB)‐filled low‐density polyethylene (LDPE) and ethylene–vinyl acetate copolymer (EVA) composites, which are candidates for positive temperature coefficient (PTC) materials. It was found that the dispersion mode of CB particles changes as a function of the matrix morphology. When the composites are irradiated to form crosslinked networks in the matrix for the elimination of negative temperature coefficient (NTC) behavior, some of the produced free radicals are also entrapped for quite a long time after the irradiation treatment. These residual radicals further enhance the interaction between CB and the matrix and further induce the crosslinking of the matrix so that the composites' conductivity changes with time as a result of the continuous variation in the contacts between the conductive fillers. To improve the quality of the conduction paths in the composites, appropriate post‐heat treatment should be carried out, which speeds up the formation of the above‐mentioned two kinds of crosslinked structures within a limited time. Annealing at 75°C for more than 10 h is believed to be an effective way. After the treatment, a balanced performance characterized by reduced room‐temperature resistivity and improved PTC intensity was obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2768–2775, 2002
Some studies on mechanical properties of wood flour/continuous glass mat/polypropylene composite
Authors: Lin Qunfang , Zhou Xiaodong , Dai Gance , Bi Yiemao 
Published: August 2002

AbstractThe mechanical properties and the surface property of wood flour/continuous glass mat/polypropylene composites have been investigated. The suitability of wood flour as a filler for continuous glass mat–reinforced polypropylene has been tested using different mesh sizes (e.g., 20 and 40 mesh), as well as by varying the weight percentage of wood flour from 0%– 30%. Moreover, different treatments such as coupling agent A‐1100 and functionalized polypropylene grafting with maleic anhydride, and so forth, have also been used to improve the compatibility of wood flour and glass fiber with the polymer resin. In addition, the effects of the surface weight of glass mat and matrix resin have been studied. The extent of the improvement in mechanical properties depends on the wood flour content and size, the surface weight of the glass mat, the matrix resin, and the surface treatment of wood flour. After adding wood flour, the contact angle of distilled water on the composite surface decreases and the polar component of surface tension increases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 536–544, 2002
Properties of silica‐filled styrene‐butadiene rubber compounds containing acrylonitrile‐butadiene rubber: The influence of the acrylonitrile‐butadiene rubber type
Authors: Choi Sung‐Seen 
Published: August 2002

AbstractBecause silica has strong filler‐filler interactions and adsorbs polar materials, a silica‐filled rubber compound exhibits poor dispersion of the filler and poor cure characteristics in comparison with those of a carbon black‐filled rubber compound. Acrylonitrile‐butadiene rubber (NBR) improves filler dispersion in silica‐filled styrene‐butadiene rubber (SBR) compounds. The influence of the NBR type on the properties of silica‐filled SBR compounds containing NBR was studied with NBRs of various acrylonitrile contents. The composition of the bound rubber was different from that of the compounded rubber. The NBR content of the bound rubber was higher than that of the compounded rubber; this became clearer for NBR with a higher acrylonitrile content. The Mooney scorch time and cure rate became faster as the acrylonitrile content in NBR increased. The modulus increased with an increase in the acrylonitrile content of NBR because the crosslink density increased. The experimental results could be explained by interactions of the nitrile group of NBR with silica. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 385–393, 2002
Structural aspects and nature of swelling medium as equilibrium swelling determinants of acrylamide and cellulosic‐based smart hydrogels
Authors: Chauhan Ghanshyam S. , Mahajan Swati 
Published: August 2002

AbstractHydroxypropylcellulose (HPC)‐based interpenetrating networks (IPN) with acrylamide (AAm) were synthesized in aqueous medium by simultaneous γ‐ray initiation in the presence of N,N‐methylenebisacrylamide (N,N‐MBAAm). The effect of the synthetic reaction conditions was evaluated for optimum network yield and networks of cellulose and some of its derivatives were obtained with AAm by using these conditions. FTIR, elemental analysis, and scanning electron micrography (SEM) for various structural aspects have characterized networks. Apart from kinetics of IPN formation, this article discusses swelling response of these novel hydrogels in different swelling media. Swelling behavior was studied as a function of synthetic reaction conditions, structure of cellulosics used, and nature of swelling medium (water, 0.5N NaOH, 0.5N HCl, and 5% NaCl). Equilibrium swelling was observed to depend on both structural and environmental factors. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1161–1169, 2002
High‐pressure differential thermal analysis of polymers
Authors: Kojima Yoshitsugu , Takahara Minoru , Matsuoka Takaaki , Takahashi Hideroh 
Published: August 2002

AbstractMelting behavior under high pressure of nylon 6, nylon 6‐clay hybrid (NCH) and poly(butylene terephthalate) was investigated by high‐pressure differential thermal analysis (DTA). It was found that the melting temperature and the pressure dependency of the melting temperature of NCH were low compared with those of nylon 6. Using the melting temperature, the pressure dependency of the melting temperature, and the heat of fusion (the enthalpy of fusion), the Clausius‐Clapeyron equation was used to determine the volume changes on melting of the polymers at atmospheric pressure ΔVm0(DTA). ΔVm0(DTA) of NCH was lower than that of the nylon 6 α‐form. The smaller ΔVm0(DTA) of NCH was attributed to the presence of nylon 6 γ‐form in NCH. The values of ΔVm0(DTA) for nylon 6 and poly(butylene terephthalate) were similar to those obtained from pressure‐volume‐temperature relationships ΔVm0(PVT) of those polymers. The entropies of fusion were constant and independent of pressures up to 100 MPa. The volume changes on melting (ΔVm in cm3/g) under high pressure can be approximately described by the following equation: ΔVm = 0.165TmVw (dTm/dP)/(dTm0/dP)/298, where Tm and Tm0 are the melting temperatures (in K) under high pressure and atmospheric pressure, respectively and Vw is the van der Waals volume of the polymer (cm3/g). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1046–1051, 2001
Expandable graphite systems for halogen‐free flame‐retarding of polyolefins. II. Structures of intumescent char and flame‐retardant mechanism
Authors: Xie Rongcai , Qu Baojun 
Published: August 2002

AbstractThe structures of the intumescent charred layers formed from polyolefin (PO) blends with expandable graphite (EG) and/or the other free‐halogen flame retardant (HFFR) and their flame‐retardant mechanism were studied by Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermal conductivity (TC) measurements. The FTIR, XPS, and LRS data showed that the carbonaceous structures of intumescent charred layers consist of EG and various numbers of condensed benzene rings and/or phosphocarbonaceous complexes attached by the P—O—C and P—N bonds or quaternary nitrogen or dehydrated zinc borate (ZB). These results and the morphologic structures observed by SEM have demonstrated that the compact structures of charred layers slow down heat and mass transfer between the gas and condensed phase and prevent the underlying polymeric substrate from further attack by heat flux in a flame. The DTA data provide the positive evidence for the flame‐retardant mechanism of the PO/EG/HFFR systems, which works by increasing the oxidation temperature and decreasing thermal oxidation heat. At the same time, the TC data reveal the flame‐retardant essence of the charred layers as good heat‐insulated materials whose TC value is only about 1/10 of the corresponding blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1190–1197, 2001
Melt/solution processable polyaniline with functionalized phosphate ester dopants and its thermoplastic blends
Authors: Paul Raji K. , Pillai C. K. S. 
Published: August 2002

AbstractPolyaniline (PANI) was doped with five novel dopants, 3‐pentadecylphenylphosphoric acid (PDPPA), pentadecylphenyl(bis)phosphoric acid [PDP(bis)PA], monocardanylphosphoric acid (MCPA), dicardanylphosphoric acid (DCPA), and phosphorylated cashew nut shell liquid prepolymer (PCNSL) and the doping behavior was studied. All dopants were synthesized from inexpensive naturally existing monomers [obtained from cashew nut shell liquid (CNSL)] having a long hydrophobic hydrocarbon side chain in the meta position of the aromatic ring. These dopants can act as plasticizing cum protonating agents for PANI so that free‐standing films of PANI could be prepared by both thermal processing and solution processing techniques. Protonation was performed either by mechanical mixing of emeraldine base and the dopant or by an in situ doping emulsion polymerization route using xylene or chloroform as the solvent. Further, conductive flexible blends of the protonated PANI with poly(vinyl chloride) (PVC) were also prepared and studied for their conductivity and related properties. The PANI–PDPPA complex obtained by the in situ doping emulsion polymerization route exhibited an exceptionally high degree of crystalline order and orientation. A maximum conductivity value of 1.8 S cm−1 was obtained for a PANI–PDPPA film hot‐pressed at 120°C. On the other hand, dopants based on cardanol having an unsaturated side chain gave only lower values. This was understood to be due the capability of the saturated analog to contribute to the ordered arrangement of PANI, thus improving the crystallinity. The conductivity values further decreased when bulky/oligomeric dopants such as PCNSL were used. The thermoplastic blends with PVC exhibited an exceptionally low‐level percolation threshold because of the plasticizing nature of the dopants. The doped polymers and blends were characterized by FTIR and UV‐visible spectroscopic methods, four‐probe conductivity measurements, XRD, SEM, TGA, and DSC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1354–1367, 2001
Ring‐banded spherulites in poly(ϵ‐caprolactone) blended with hydroxyethyl cellulose acetate as an indication for partial miscibility
Authors: Xiao Q. , Yan S. , Rogausch K. D. , Petermann J. , Huang Y. 
Published: August 2002

AbstractThe morphologies of poly(ϵ‐caprolactone) (PCL) blends with hydroxyethyl cellulose acetate (HECA), a thermotropic liquid crystalline polymer (TLCP), were investigated by optical microscopy. It is demonstrated that when the pure PCL is crystallized from the melt, a spherulitic morphology arises with distinct Maltese crosses. With the addition of the HECA, the spherulites of the PCL/HECA blends show not only the Maltese crosses but also distinct extinction rings (i.e., a ring‐banded spherulitic morphology). The average periodic distance of the extinction rings decreases drastically with the increase of the HECA content from 0.5 to 5 wt % in the mixture, whereas it decreases only slightly with the further increase of HECA. The periodicity of extinction rings is also influenced by the crystallization temperature. The formation of the ring‐banded spherulites of PCL in PCL/HECA blends is explained in terms of stress‐induced twisted lamellar crystallization and used as an indication of the molecular solubility of the HECA in the PCL. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1681–1686, 2001