bluuebunny/crossref_metadata_2025 huggingface dataset:
Specialty chemicals from vegetable oils: achievements within the Greenchem research program
Authors: Törnvall Ulrika , Hatti‐Kaul Rajni
Published: April 2007

Industrial biotechnology offers promising tools for transforming renewable resources into useful products. The research program Greenchem was started in 2003 with the goal to demonstrate that environmentally benign specialty chemicals can be produced from renewables using biocatalysis. This article provides a summary of the enzymatic processes on oleochemicals successfully established so far within the program, including production of wax esters, fatty epoxides, and biosurfactants. The environmental performance of these products is also discussed and compared to the corresponding fossil oil based products, from a life cycle perspective. A general observation has been that biocatalytic reactions are more selective and energy‐efficient than the corresponding chemical processes; however, continued efforts are required for developing biocatalyst preparations with good operational stability in order to make biocatalysis an economically attractive option for the chemical industry. Furthermore, the choice of the raw material is of utmost importance in achieving the desired environmental advantages over the fossil based resources.
Measurement of fatty acids in whole soybeans with near infrared spectroscopy
Authors: Hurburgh Charles R.
Published: April 2007

Improvement of nutritional and/or functional properties of soybean oil by modification of soy fatty acid composition is one of the objectives of plant breeders. A major element of breeding is rapid identification and tracking of traits in seed samples. This discussion summarizes the progression of whole‐soybean fatty acid calibration developments at Iowa State University. Emphasis was placed on linolenic acid (18:3) and total saturates (16:0 + 18:0). Normal soybeans have 12–20% (of the oil) saturated fats; modified low saturate soybeans have 6–8% saturated fats. Normal soybeans have 6–12% linolenic acid; modified low linolenic soybeans have 1–3% linolenic acid. Infratec 122x/1241 and Bruins OmegaG NIRS units were calibrated to measure fatty acid levels as a percentage of total oil content, in whole soybeans. The first Infratec calibrations (in 1998) did not remain accurate as soybean genetics changed. Iterations of the calibration process yielded calibrations for total saturates and linolenic acid with standard errors of prediction (on 2005 crop samples not included in the calibration pool) of 1.0% percentage points and 0.8% points, respectively. These were sufficient to classify modified versus normal concentrations of the two fatty acids. The NIRS units could not determine the specific percentages within the classes of modified and normal soybeans.
Schrödinger equations of higher order
Authors: Ascanelli Alessia , Cicognani Massimo
Published: April 2007

We are interested in finding the sharp regularity with respect to the time variable of the coefficients of a Schrödinger type operator in order to have a well‐posed Cauchy Problem in H∞. We consider both the cases of the first derivative that breaks down at a point t0 and of Log‐Lipschitz coefficients. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Cauchy problem for quasilinear SG‐hyperbolic systems
Authors: Cappiello Marco , Zanghirati Luisa
Published: April 2007

We study the Cauchy problem for a class of quasilinear hyperbolic systems with coefficients depending on (t, x) ∈ [0, T ] × ℝn and presenting a linear growth for |x | → ∞. We prove well‐posedness in the Schwartz space 𝒮 (ℝn ). The result is obtained by deriving an energy estimate for the solution of the linearized problem in some weighted Sobolev spaces and applying a fixed point argument. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some remarks on the Picard curves over a finite field
Authors: Takizawa Yoh
Published: April 2007

In this paper we study the Newton polygon of the L ‐polynomial L (t) associate to the Picard curves

y3 = x4 – 1, y3 = x4 – x

defined over a finite field 𝔽p . In the former case we get a complete classification. In the latter case we obtained a partial result.

As a consequence of our result we obtain a criterion to find a supersingular Picard curves for the above two cases. Our main results are stated in Theorems 3.1 and 4.1. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bodies of constant width in arbitrary dimension
Authors: Lachand‐Robert† Thomas , Oudet Édouard
Published: April 2007

We give a number of characterizations of bodies of constant width in arbitrary dimension. As an application, we describe a way to construct a body of constant width in dimension n, one of its (n – 1)‐dimensional projection being given. We give a number of examples, like a four‐dimensional body of constant width whose 3D‐projection is the classical Meissner's body. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extending symbolic brands using their personality: Examining antecedents and implications towards brand image fit and brand dilution
Authors: Lau Kong Cheen , Phau Ian
Published: April 2007

This research provides a framework to achieve two objectives. First, it helps us to understand the implications of congruency of information, motivation, and perceived prestige orientation as antecedents to brand personality fit. Second, it examines the mediating role of brand image fit between brand personality fit and dilution of brand affect. The above is explained by using elaboration theory, conceptual coherence theory, and goal‐derived categorization theory. The results of the implication of elaboration theory on brand personality fit were mixed. While congruency of personality dimensions between parent and extension brands has bearings towards brand personality fit, the motivation of processing information did not. In contrast to brand image fit, this study showed that the prestige orientation of a brand did not influence brand personality fit. The subsequent mediation analysis demonstrated that brand personality fit is positively related to brand image fit, but neither of these two variables has any influence on dilution of brand affect. © 2007 Wiley Periodicals, Inc.
The effects of optimal time of day on persuasion processes in older adults
Authors: Yoon Carolyn , Lee Michelle P. , Danziger Shai
Published: April 2007

Past research demonstrates that the majority of older adults (60 years and older) perform resource‐demanding tasks better in the morning than in the afternoon or evening. The authors ask whether this time‐of‐day effect also impacts persuasion processes performed under relatively high involvement. The data show that the attitudes of older adults are more strongly affected by an easy‐to‐process criterion, picturerelatedness, at their non‐optimal time of day (afternoon) and by a more‐difficult‐to‐process criterion, argument strength, at their optimal time of day (morning). In contrast, the attitudes of younger adults are affected primarily by argument strength at both their optimal (afternoon) and non‐optimal (morning) times of day. Process‐level evidence that accords with these results is provided. The results accentuate the need for matching marketing communications to the processing styles and abilities of older adults. © 2007 Wiley Periodicals, Inc.
Reversibly Switchable Double‐Responsive Block Copolymer Brushes
Authors: Wang Xi , Xiao Xing , Wang Xiaohong , Zhou Jianjun , Li Lin , Xu Jun , Guo Baohua
Published: April 2007

Poly(2‐hydroxyethyl methacrylate)‐block‐poly(N‐isopropylacrylamide) (PHEMA‐b‐PNIPAM) was prepared by controlled surface‐initiated ATRP from silicon substrates, and the resulting block copolymers were successfully converted into the corresponding PSEMA‐b‐PNIPAM by esterification of the hydroxy groups on the PHEMA block using excess of succinic anhydride. The PSEMA‐b‐PNIPAM block copolymer brushes respond to both temperature and pH stimuli. The double‐responsive behavior of the block copolymer brushes in solution was investigated by height imaging and force–distance measurements of AFM. The results clearly show the responsive behavior of the smart block copolymer brushes.

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Emulsion‐Induced Ordered Microporous Films Based on Micelles of Amphiphilic Poly(ethylene oxide)‐block‐Poly(methyl methacrylate) Diblock Copolymers
Authors: Ishizu Koji , Makino Masataka , Uchida Satoshi
Published: April 2007

Well‐defined PEO‐b‐PMMA was prepared, initiated by macroinitiator PEO‐Br, by means of ATRP, where esterification of the terminal hydroxyl group of PEO with 2‐bromoisobutyryl bromide yielded a macroinitiator PEO‐Br. Highly ordered microporous films (hexagonal pattern) were constructed by emulsion micelles of such amphiphilic diblock copolymer formed from a solution with CHCl3/H2O/THF = 100:5:10 (v/v). We also constructed the microporous films using diblock copolymer by the current water‐assisted method.

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Isothermal Crystallization of Isotactic Poly(propylene) Studied by Superfast Calorimetry
Authors: Silvestre Clara , Cimmino Sossio , Duraccio Donatella , Schick Christoph
Published: April 2007

The isothermal crystallization behavior and the structure and morphology of isotactic poly(propylene) (iPP) and iPP/hydrogenated hydrocarbon resin (HR) 90/10 blend were analyzed. To cover the entire temperature range, isothermal crystallizations were studied using superfast calorimetry at a high cooling rate in the range 0 to 110 °C, and by conventional DSC at a low cooling rate in the range 120 to 140 °C. Structural and morphological changes due to the different thermal treatments were also analyzed. The complete crystallization curve ranging from Tg to Tm showed bimodal crystallization behaviors for both iPP and iPP/HR 90/10 blend. This result is explained by taking into consideration the polymorph properties of iPP. It is in fact assumed that the curve from Tg to 60 °C referred mainly to the crystallization kinetics of the iPP mesomorphic form by homogeneous nucleation, whereas the curve from 60 °C to Tm mainly represented the crystallization kinetic curve for the monoclinic α form by heterogeneous nucleation. This hypothesis is confirmed by the analysis of the structures obtained using wide angle X‐ray experiments. Moreover, the addition of HR to iPP causes a drastic reduction in the crystallization rate of iPP in both regions due to the diluent effect of the miscible resin.

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Additional Retardation in RAFT Polymerization: Detection of Terminated Intermediate Radicals
Authors: Bathfield Maël , D'Agosto Franck , Spitz Roger , Ladavière Catherine , Charreyre Marie‐Thérèse , Delair Thierry
Published: April 2007

The reversible addition‐fragmentation chain transfer (RAFT) polymerization of N‐acryloylmorpholine (NAM) is performed using three dithioesters (DT) as chain transfer agents (CTA) that incorporate a morpholine (morpholine‐DT), a biotin (biotin‐DT), or a sugar (sugar‐DT) moiety in the R group. PolyNAM chains of controlled characteristics are synthesized. An unexpected behavior is observed with morpholine‐DT, described as an ‘additional retardation’, which is especially visible when low molar masses are targeted ($\overline M _{\rm n} $ < 5 000 g · mol−1). In that particular case, further investigations using MALDI‐TOF mass spectrometry show the presence of terminated intermediate radicals (IRs), which corroborates the assumption based on a specific protection of IR according to the nature of the α‐chain‐end.

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A Novel Benzoxazole‐Containing Poly(N‐isopropylacrylamide) Copolymer as a Multifunctional Sensing Material
Authors: Yang Chang‐Chung , Tian Yanqing , Chen Ching‐Yi , Jen Alex K.‐Y. , Chen Wen‐Chang
Published: April 2007

We report a novel multifunctional material, poly(N‐isopropylacrylamide) (PNIPAAm) containing 2‐(2‐hydroxyphenyl)benzoxazole (HPBO), for sensing pH, zinc ion concentration, or temperature. By titration with zinc ions, a clear blue‐shifted emission with a high quantum efficiency was detected since the zinc complex prevented the nonradiative decay pathways of the HPBO moiety. The fluorescence characteristics of the copolymer were similar at various acidic or neutral conditions. However, a large blue shift on the emission maximum was exhibited under the basic condition, due to the disruption of the ESIPT process by the phenolate anion. The LCST affected the fluorescence properties significantly at the basic condition because the incompatibility between the PNIPAAm chain and phenolated HPBO moieties resulted in aggregation formation. The present study demonstrates that the new benzoxazole‐containing PINPAAm copolymer could be potentially used as multifunctional sensing material.

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Ethylene–Norbornene Copolymerization by Carbon Nanotube‐Supported Metallocene Catalysis: Generation of High‐Performance Polyolefinic Nanocomposites
Authors: Bredeau Stéphane , Boggioni Laura , Bertini Fabio , Tritto Incoronata , Monteverde Fabien , Alexandre Michaël , Dubois Philippe
Published: April 2007

Homogeneous surface coating of multi‐walled carbon nanotubes is achieved for the first time by in situ copolymerization of ethylene (E) and 2‐norbornene (N) as catalyzed directly from the nanotube surface previously treated by a highly active metallocene‐based complex, i.e., rac‐Et(Ind)2ZrCl2/MMAO‐3A. The copolymerization reaction allows for the destructuration of the native nanotube bundles, which upon further melt blending with an ethylene–vinyl acetate copolymer (27 wt.‐% vinyl acetate) matrix, leads to high‐performance polyolefinic nanocomposites. The microstructural analysis of the surface‐coating copolymer was carried out by 13C NMR spectroscopy and allowed determination of the actual N content incorporated along the chains. Depending on the experimental conditions used (e.g., E pressure, solvent, feed N concentration) the relative quantity of E–N copolymer can be tuned, as well as the N content in the formed copolymers and accordingly their glass transition temperature.

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Polypyrrole Nanospheres with Magnetic and Cell‐Targeting Capabilities
Authors: Wuang Shy Chyi , Neoh Koon Gee , Kang En‐Tang , Pack Daniel W. , Leckband Deborah E.
Published: April 2007

The preparation of polypyrrole/Fe3O4 nanospheres by a facile mini‐emulsion polymerization method is investigated using poly(ethylene glycol), poly(ethylene oxide), poly(vinyl alcohol), and hyaluronic acid as surfactants. Hyaluronic acid is deemed the most suitable surfactant since it results in well‐dispersed nanospheres of 80–100 nm, and offers the advantages of biocompatibility, cell adhesive property, and the availability of functional groups for attachment of other molecules. These polypyrrole/Fe3O4 nanospheres are magnetic and can be further functionalized with a cancer antibody, herceptin. Our results show that this combination of hyaluronic acid and herceptin results in high specific uptake of the nanospheres by cancer cells.

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Microwave‐Assisted Synthesis of Crosslinked Poly(vinyl alcohol) Nanocomposites Comprising Single‐Walled Carbon Nanotubes, Multi‐Walled Carbon Nanotubes, and Buckminsterfullerene
Authors: Nadagouda Mallikarjuna N. , Varma Rajender S.
Published: April 2007

We report a facile method to accomplish the crosslinking reaction of PVA with SWNTs, MWNTs, and C‐60 using MW irradiation. Nanocomposites of PVA crosslinked with SWNT, MWNT and C‐60 were prepared expeditiously by reacting the respective carbon nanotubes with 3 wt.‐% PVA under MW irradiation, maintaining a temperature of 100 °C, representing a radical improvement over literature methods to prepare such crosslinked PVA composites. This general preparative procedure is versatile and provides a simple route to manufacture useful SWNT, MWNT and C‐60 nanocomposites.

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Simultaneous Binary Mixed Homopolymer Brush Formation by Combining Nitroxide‐Mediated Radical Polymerization and Living Cationic Ring‐Opening Polymerization
Authors: Wang Ying , Brittain William J.
Published: April 2007

A simple approach for one‐pot, one‐step binary mixed homopolymer brush synthesis was devised by combining nitroxide‐mediated radical polymerization of styrene and living cationic ring‐opening polymerization of 2‐phenyl‐2‐oxazoline. Surface characterization techniques such as ATR‐FTIR, ellipsometry, XPS, and contact angle measurements were performed in this research. The mixed homopolymer brush exhibited reversible surface property changes when subjected to different solvents.
Macromol. Rapid Commun. 7/2007
Authors: Wuang Shy Chyi , Neoh Koon Gee , Kang En‐Tang , Pack Daniel W. , Leckband Deborah E.
Published: April 2007

Cover: Magnetic polypyrrole‐Fe3O4 nanospheres with surface immobilized herceptin show a > 7‐fold increase in efficiency in targeting HCC1954 breast cancer cells over that of non‐functionalized nanospheres. Further details can be found in the article by S. C. Wuang, K. G. Neoh,* E.‐T. Kang, D. W. Pack, and D. E. Leckband on page 816.
Effects of calcitonin and parathyroid hormone on the regulation of cabindin‐D9k in the uterus, placenta, and fetal membrane of rats related to blood calcium level during late gestation
Authors: Hong Eui‐Ju , Choi Kyung‐Chul , Hyun Sang‐Hwan , Jeung Eui‐Bae
Published: April 2007

Calbindin‐D9k (CaBP‐9k) gene is expressed in the uterus of pregnant rats, which is regulated by steroid hormones during estrous cycle or gestation. We hypothesized that there is a positive correlation between altered CaBP‐9k expression and change in one or more of the hormones to provide a clue to the mechanism responsible for the altered calcium levels in the uterus, placenta, and fetal membrane during late gestation. Thus, in the present study, we investigated the effects of the hormones including estradiol (E2), calcitonin (CT), and parathyroid hormone (PTH) on the regulation of CaBP‐9k in these tissues. There was an increase in the level of CaBP‐9k in the uterus, placenta, and extra‐embryonic membrane at late gestation, as blood calcium level increased. The protein level of CaBP‐9k remained lower in the uterus at two‐thirds of pregnancy, and then it rebounded abruptly during late pregnancy. During late gestation, E2 is postulated to be a dominant factor in the regulation of uterine CaBP‐9k gene expression. Furthermore, we assumed that there is a positive correlation between altered expression of CaBP‐9k and blood calcium level during pregnancy. The present study demonstrated the regulation of CaBP‐9k mRNA in the uterus, placenta, and fetal membrane of rats, implying a role for CaBP‐9k gene in the control of blood calcium in placenta and the calcium passing from maternal blood to fetal circulation. Taken together, these results suggest that major alterations in calcium metabolism caused by maternal thyroparathyroidectomy (TPTX), are sufficient to affect the changes in reproductive tissues during late pregnancy. In addition, an increase of blood calcium level is one of the most significant factors in the regulation of CaBP‐9k at the transcriptional and/or translational levels in the reproductive tissues during late pregnancy. Mol. Reprod. Dev. 74: 1188–1197, 2007. © 2007 Wiley‐Liss, Inc.
Electrodiagnostic studies of the facial nerve in peripheral facial palsy and hemifacial spasm
Authors: Valls‐Solé Josep
Published: April 2007

Electrodiagnostic (EDX) assessment is one of the most important aspects in the evaluation of the two most common disorders of the facial nerve: facial palsy and hemifacial spasm. Facial palsy is usually an acute disorder that resolves in a few weeks but, in a number of cases, leads to a postparalytic facial syndrome featuring muscle synkinesis, myokymia, and involuntary mass contractions of muscles on the affected side. Hemifacial spasm is usually a chronic disorder characterized by paroxysms of involuntary, clonic, and synchronous twitching of all facial muscles on the affected side. EDX studies provide information on lesion location and severity, pathophysiology underlying the two disorders, and differential diagnosis between syndromes presenting with abnormal facial muscle activity. This monograph is intended to describe the most relevant EDX findings in the two disorders and the most appropriate timing for the examinations in order to provide useful information for prognosis and therapeutic decision‐making. Muscle Nerve, 2007
Matrix metalloproteinases in neuromuscular disease
Authors: Renaud Susanne , Leppert David
Published: April 2007

Matrix metalloproteinases (MMPs), a family of zinc‐dependent endoproteinases, are effector molecules in the breakdown of the blood–brain and blood–nerve barrier, and promote neural tissue invasion by leukocytes in inflammatory diseases of the central and peripheral nervous systems. Moreover, MMPs play an important role in synaptic remodeling, neuronal regeneration, and remyelination. Recent work concerning MMPs in patients with neuropathy, myopathy, spinal cord injury, and amyotrophic lateral sclerosis (ALS), and in corresponding animal models, is discussed in this review. Muscle Nerve, 2007
The H reflex from the abductor brevis hallucis muscle in healthy subjects
Authors: Versino Maurizio , Candeloro Elisa , Tavazzi Eleonora , Moglia Arrigo , Sandrini Giorgio , Alfonsi Enrico
Published: April 2007

In order to evaluate the clinical applicability of a neurophysiological technique, information is required about the effect of technical and subjective factors on the measured parameters, and whether these measures are reliable. The reliability of measurement of a given parameter is inversely related to the variability shown by a set of measurements of that parameter made on the same subject under similar conditions. Reliable measures are fundamental to the clinical utility of any technique. We evaluated the reliability using the intraclass correlation coefficient (ICC), and assessed both single‐point and test–retest normal limits for H‐reflex parameters of abductor brevis hallucis (ABH). The H reflex from the ABH muscle was recorded in 36 of 43 subjects, but could not be elicited in 7 of 11 subjects who were >60 years of age. The Hmax latency increased as height increased, whereas Hmax amplitude and Hmax/Mmax amplitude ratio decreased as age and height increased. The Hmax latency and Hmax/Mmax amplitude ratio, but not Hmax amplitude, proved to be reliable. The usefulness of the H reflex from ABH in the evaluation of S2 radiculopathies is described. Muscle Nerve, 2007
Autosomal‐recessive and X‐linked forms of hereditary motor and sensory neuropathy in childhood
Authors: Ouvrier Robert , Geevasingha Nimeshan , Ryan Monique M.
Published: April 2007

The hereditary motor and sensory neuropathies (HMSNs, Charcot–Marie–Tooth neuropathies) are the most common degenerative disorders of the peripheral nervous system. In recent years a dramatic expansion has occurred in our understanding of the molecular basis and cell biology of the recessively inherited demyelinating and axonal neuropathies, with delineation of a number of new neuropathies. Mutations in some genes cause a wide variety of clinical, neurophysiologic, and pathologic phenotypes, rendering diagnosis difficult. The X‐linked forms of HMSN represent at least 10%–15% of all HMSNs and have an expanded disease spectrum including demyelinating, intermediate, and axonal neuropathies, transient central nervous system (CNS) dysfunction, mental retardation, and hearing loss. This review presents an overview of the recessive and X‐linked forms of HMSN observed in childhood, with particular reference to disease phenotype and neurophysiologic and pathologic abnormalities suggestive of specific diagnoses. These findings can be used by the clinician to formulate a differential diagnosis and guide targeted genetic testing. Muscle Nerve, 2007
Intraoperative muscle measurements reveal a relationship between contracture formation and muscle remodeling
Authors: Pontén Eva , Gantelius Stefan , Lieber Richard L.
Published: April 2007

Children with cerebral palsy often have spasticity of both the extensors and flexors, but how and why a flexion contracture of the wrist will develop during growth is not thoroughly understood. In order to understand the muscle adaptations that occur during contracture formation, the relationship between intraoperative sarcomere length and the extent of contracture was measured in 23 children (average age, 14.3 ± 2.9 years) undergoing tendon transfers involving the flexor carpi ulnaris (FCU) or extensor carpi radialis brevis (ECRB) muscles. For both ECRB and FCU, sarcomere lengths measured intraoperatively were longer compared to sarcomere lengths predicted from a regression relationship obtained from “control” patients with radial nerve injury (P < 0.001). The most interesting aspect of the long FCU sarcomere lengths measured was that there was a highly significant correlation between the degree of contracture formation and intraoperative sarcomere length (r2 = 0.5, P < 0.005). These data clearly show that greater contracture severity is associated with longer intraoperative FCU sarcomere length. No such correlation was observed for the ECRB. The data suggest that the clinical presentation of the contracture is related to degree of FCU, but not ECRB adaptation, to the central nervous system lesion. Muscle Nerve, 2007
Properties of epoxy nanoclay system based on diaminodiphenyl sulfone and diglycidyl ether of bisphenol F: influence of post cure and structure of amine and epoxy
Authors: Ingram Sharon E , Liggat John J , Pethrick Richard A
Published: April 2007

Materials were prepared with Cloisite 30B, diglycidyl ether of bisphenol F and diaminodiphenyl sulfone (DDS) to investigate the relationship between exfoliation and property enhancement. A higher level of exfoliation was found with 4,4′‐DDS than in the material cured with 3,3′‐DDS. The material with 4,4′‐DDS that exhibited a higher degree of exfoliation also resulted in larger improvements in physical properties with nanoclay. Increasing the ratio of trifunctional to difunctional epoxy led to a significant decrease in the level of clay dispersion. Increasing the ratio of trifunctional epoxy in the nanocomposite also caused a decrease in Tg with the addition of nanoclay. However, an increase in Tg with increasing clay loadings was detected in samples with a higher degree of exfoliation, with only difunctional epoxy. Similar behaviour was found for samples with and without a post cure. Excessive post cure led to a decrease in thermal stability in Cloisite 30B‐containing samples. Copyright © 2007 Society of Chemical Industry
Polymerizable oil‐in‐oil emulsions: poly(vinyl pyrrolidone) dispersions in reactive PDMS medium
Authors: Hariri Kamal , Al Akhrass Samer , Delaite Christelle , Moireau Patrick , Riess Gérard
Published: April 2007

The system N‐vinyl‐2‐pyrrolidone (VP)/polydimethylsiloxane diglycidylether (PDMS‐DGE) is a typical example of an oil‐in‐oil emulsion formed by two non‐miscible liquids, where both phases are polymerizable in a ‘one‐pot’ procedure by two distinct reaction mechanisms. These oil‐in‐oil emulsions were characterized by their stability and by the particle size of the dispersed VP phase. Non‐aqueous dispersions (NADs) are obtained in a first step by free radical polymerization of the dispersed VP phase. The reaction kinetics, studied as a function of the initiator type and concentration, show that the polymerization rate is mainly influenced by the partition coefficient of the initiator between both phases. The NAD particle size could be tailored from a micrometer to a nanometer range by in situ formation of PVP‐PDMS graft copolymer. Hydrophilic–hydrophobic two‐phase materials can be obtained by polycondensation, in the presence of polyamines, of the epoxy‐functionalized PDMS continuous NAD phase. Copyright © 2007 Society of Chemical Industry
Bicyclo‐orthoester as a low‐shrinkage additive in cationic UV curing
Authors: Sangermano Marco , Malucelli Giulio , Delleani Gabriele , Priola Aldo
Published: April 2007

A commercially available bicyclo‐orthoester (BOE) was used as low‐shrinkage additive for cationic UV curing of epoxy resins. A high reactivity of BOE by ring‐opening homopolymerization has been observed under cationic UV curing conditions. The BOE and trimethylolpropane triglycidyl ether monomers are compatible and give rise to a cured copolymeric network, under UV irradiation, with a flexibilization increase by increasing the BOE content in the photocurable formulation. Shrinkage after photopolymerization shows a linear reduction by increasing the BOE content in the photocurable formulation; a volume expansion upon polymerization is reached in the presence of 50 wt% of the additive. Copyright © 2007 Society of Chemical Industry
Fracture toughness evaluation of K resin® grafted with maleic anhydride‐ compatibilized polyamide 6/K resin® blends
Authors: Jing Bo , Dai Wenli , Liu Pengsheng , Zhang Ping
Published: April 2007

The mechanical behavior and fracture toughness of polyamide 6 (PA6)/K resin® (K) blends, with and without maleic anhydride‐grafted K resin® (K‐g‐MAH) incorporated, have been investigated. The results showed that the tensile strength, elongation at break and impact strength of PA6/K blends were improved considerably on incorporating K‐g‐MAH. This results from the improvement of compatibility between the PA6 and K phases. The essential work of fracture (EWF) method was employed to determine the fracture toughness of PA6/K blends with and without K‐g‐MAH incorporated. The effect of composition on the EWF parameters of the blends was particularly investigated. The results showed that a significant improvement in the specific EWF (we) of PA6/K blends occurred when K‐g‐MAH was incorporated. The effect of K‐g‐MAH content on the fracture toughness of the PA6/K/K‐g‐MAH blends was mainly achieved through its influence on the specific essential and nonessential work of fracture in the yielding process. Copyright © 2007 Society of Chemical Industry
Glass transition of poly(oxymethylene)
Authors: Suzuki Hidematsu , Grebowicz Janusz , Wunderlich Bernhard
Published: April 2007

Heat capacity data of semicrystalline poly(oxymethylene) samples. Delrin and Celcon, are analysed in order to discuss the glass transition behaviour of this polymer. There are two types of non‐crystalline poly(oxymetheylene). the mobile and rigid amorphous parts. The glass transition of the former occurs in a rather wider range of temperature: it starts at 180 K and could end at 265 K. The latter, under restraint due to the crystallites, remains frozen up to the melting temperature.
1H n.m.r. spectra of ring‐opened polymers of 1‐methylbicyclo[2.2.1]hept‐2‐ene
Authors: Hamilton James G. , Ivin Kenneth J. , Rooney John J.
Published: April 2007

1H n.m.r. spectra of the title polymers containing 0%, 57% and 100% cis double bonds and having various degrees of head‐tail (HT) bias have been analysed. The olefinic protons give distinct signals for HH, HT and TT trans dyads, also for HT and TT cis dyads, but HH cis dyads are not present in any polymer. The ring protons adjacent to the double bonds also give distinct cis and trans signals as do the methyl protons. The latter give four lines, assigned to cc, ct, tc and tt double bond pairs, and their intensities indicate a somewhat blocky cis/trans distribution for polymers having a high cis content. There is no fine structure which can be positively assigned to ring tacticity effects.
Structure and properties relationships of epoxy resins part 1: Crosslink density of cured resin: (I) model resins synthesis
Authors: Chung  , Lau H. , Hodd Kenneth A. , Wright William W.
Published: April 2007

Two model epoxy resin precursors based on the N‐glycidyl derivatives of 4.4'‐diaminodiphenylene methane (DDM) were prepared: N,N bis‐(2,3‐epoxypropyl)‐N′,N″‐dimethyl‐4.4'‐diaminodiphenylene methane (G2A); N.N′ bis‐(2,3‐epoxypropyl)‐N,N′‐dimethyl‐4,4'‐diaminodiphenylene methane (G2S). To prepare these, aniline or N‐methyl aniline was reacted with epichlorohydrin, using acetic acid as catalyst. The products were coupled via acid‐catalysed condensations in the presence of formaldehyde or with N,N‐dimethylaminobenzyl alcohol. The coupled chlorohydrins formed were then dehydrochlorinated to form the desired product. All reactions were monitored and purifications of the crude products were effected by high pressure liquid chromatographic techniques. The products were characterised by proton and carbon‐13 nuclear magnetic resonance, infrared and mass spectroscopy, elemental and titrametric analysis. Results were compared with those obtained for tetra‐N‐glycidyl‐4,4'‐diaminodiphenylene methane (TGDDM). All the data confirmed the structures of the model resins. These, together with TGDDM. will be used to prepare epoxy resin networks of controlled crosslink density and chemical homogeneity.
Comb‐branched poly(alkyl itaconates) containing pendant ethylene amine groups
Authors: Cowie John M. G. , Wadi Nabil M. A.
Published: April 2007

Comb‐branched copolymers containing ethylene amine side chains of the general structure ‐NH(CH2CH2NH)xH with x=1, 2, 3 and 4, were prepared by the reaction of poly(monoalkyl‐codialkyl itaconate)s, using an excess of the appropriate diamine in the presence of dicyclohexylcarbo‐diimide. Incorporation of ethylene amine units in the itaconate copolymers resulted in an increase in the glass transition temperature (Tg) and in the complex modulus of the modified copolymers above Tg. Both effects were proportional to the ethylene amine content of the copolymers. Chemical modification also occurred when samples were heated to about 450 K when imide formation was detected.
X‐ray scattering from directionally crystallised pentadecaethylene glycol di‐n‐heneicosyl ether
Authors: Swales Timothy G. E. , Yeates Stephen G. , Booth Colin
Published: April 2007

X‐ray scattering from continuously rotated samples of directionally crystallised pentadecaethylene glycol di‐n‐heneicosyl ether falls on a pattern of layer lines which is readily interpreted. The unit cell is orthogonal with a=0.938nm. b=9.13nm and c=0.916nm. and with four molecules per unit cell.
Studies on chitin 3—effect of coagulants and annealing on the preparation and the properties of chitin membrane
Authors: Aiba Sei‐Ichi , Izume Masato , Minoura Norihiko , Fujiwara Yukihiko
Published: April 2007

Chitin membrane was prepared by casting a N,N‐dimethyl acetamide, N‐methyl 2‐pyrrolidone and lithium chloride (DMA‐NMP‐LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2‐Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2‐propanol and water. The membrane obtained in 2‐propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms of crystallinity.
The radiation crosslinking and scission of ethylene‐propylene copolymers studied by solid‐state nuclear magnetic resonance
Authors: O'Donnell James H. , Whittaker Andrew K.
Published: April 2007

Methyl groups from chain scission and H‐crosslinks have been identified by solid‐state nuclear magnetic resonance in amorphous ethylene‐propylene copolymers containing 23 and 36 mole % propylene after γ‐irradiation to 10 MGy at 30°C. G (scission) and G (crosslink) values determined from the n.m.r. spectra and by extraction are in agreement, which suggests that the crosslinks are not clustered. This may differ from the situation in polyethylene where there is a substantial crystalline content. G(S). G(X) and the ratio G(S)/G(X) increase with increasing propylene content of the copolymers.
Bioactive polymers XXIX—immobilisation of α‐amylase on Biozan R
Authors: Dumitriu Severian , Popa Marcel
Published: April 2007

The immobilisation of α‐amylase (E.C.3.2.1.1) on Biozan R with dicyclohexyl carbodiimide as an activator has been studied. The reaction was proved to be influenced by the enzyme support and activator support ratios as well as by the reaction duration. The function correlating the coupled enzyme activity with process parameters was derived by processing the experimental results obtained by means of a second order, composite, centrate, rotatable experimental design, using the multiple regression method. The activity of the coupled enzyme was dependent on the temperature and pH of the incubation reaction. The Michaelis‐Menten constant is higher for the immobilised enzyme as compared with the free one.
Continuous alcohol production from whey permeate using immobilised cell reactor systems
Authors: Marwaha Satwinder S. , Kennedy John F.
Published: April 2007

The present paper reports the performance of a bioreactor packed with alginate‐entrapped Kluyveromyces marxianus NCYC179 for continuous fermentation of whey permeate to ethanol. A maximum ethanol productivity as 28.21 gl−1 h−1 was attained at D=0.42h−1 and 75% lactose consumption (substrate feed rate in the inflowing medium was 200 g lactose I−1). However, the higher dilution rates (0.6‐1.Oh−1) resulted in poor productivities and higher substrate washout in the effluent samples. The maximum specific ethanol production (qpi) and maximum specific lactose uptake (qsi) of the immobilised Kluyveromyces marxianus NCYC179 was found to be 3.88g ethanol/g immobilised cell/hx10−2 and 8.75g lactose consumed/g immobilised cell/hx10−2 respectively. A bead size of 2.5 mm in diameter and activation period of 24h of alginate beads in lactose solution (10%) prior to their packing in column reactor were found to support the efficient working of the bioreactor. The immobilised cell bioreactor system was operated continuously at a constant dilution rate of 0.15h−1 and 10% lactose for 562 h without any significant change in the efficiency (varied from 84 to 88% of theoretical) and viability of the entrapped yeast cells (dropped from 84 to 81%).
Differential scanning calorimetric investigation of polymerisation of epoxy resin based on phenolphthalein with phthalic anhydride
Authors: Shah Praful P. , Parsania Pursottam H. , Patel Shanti R.
Published: April 2007

Polymerisation of phenolphthalein‐based epoxy resin with phthalic anhydride has been investigated by differential scanning calorimetry. The overall polymerisation kinetics were found to be independent of the concentration of phthalic anhydride and scan rate. The polymerisation was found to follow a simple Arrhenius‐type temperature dependence up to about 80% completion.
Effects of hydrolysis on the physical properties of short glass‐fibre reinforced poly(ethylene terephthalate)
Authors: Haworth Barry , Walsh Geraldine M.
Published: April 2007

The mechanical fracture strength and toughness of short‐fibre composites, injection moulded from compounds of poly(ethylene terephthalate) (PET) containing 10 and 30% (by weight) (w/o) glass, have been investigated and the dependence upon matrix hydrolytic stability determined. Mouldings have been characterised by several physical techniques to evaluate molecular weight, degradation rates, crystallinity and morphology, whilst time‐dependent gravimetric data were derived to quantify sorption kinetics and allow comparisons with theoretical reaction rates to be made. During melt processing, PET is hydrolysed extremely rapidly by traces of moisture (<0.02w/o). yet the inherent strength of moulded composites declines significantly only below an apparently critical molecular weight. However, on long‐term humid ageing in hot water, impact behaviour especially is rendered more complex by simultaneous crystallisation, molecular reorder and losses of interfacial bond strength.
Orientation‐strain behaviour of crosslinked rubbers
Authors: Mitchell Geoffrey R.
Published: April 2007

Procedures for the evaluation of quantitative orientation parameters using wide‐angle x‐ray scattering data are outlined. Data are presented for crosslinked natural rubber. a copolymer of polyethylene and polyvinylacetate and for polymethylmethacrylate. These quantitative orientation data are compared to the predictions of models of rubber elasticity. Critical comparisons are made with affine and phantom chain models and the variable network constraint model recently introduced by Erman and Flory. The effects of entanglements and segmental interactions are also considered. An approach is introduced which allows the evaluation of the level of intersegmental interaction contribution to the orientation‐strain behaviour.
Molecular models of polymer networks and constitutive equations of rubber elasticity
Authors: Ziabicki Andrzej , Walasek Janusz
Published: April 2007

Equilibrium elastic behaviour of crosslinked polymers (networks) is analysed both from the macroscopic (phenomenological) and microscopic (molecular) points of view. Molecular mechanisms possibly responsible for non‐linear rubber elasticity are discussed. They include: conformational entropy of network chains at small and large extensions, hindered rotation of such chains and intra‐chain point interactions, dipole‐dipole interactions between asymmetric chain segments, and topological constraints leading to chain entanglement.
Dynamical considerations of network properties
Authors: Edwards S. F.
Published: April 2007

Elasticity is discussed as an aspect of viscoelasticity, which is described by the tube model. The effects of both crosslinks and entanglements contribute to this model and a discussion of how these effects can be quantified is given. At high enough concentration, entanglements ensure the existence of elastic effects even without crosslinks, and a theory is presented on how this dynamical phase change comes about.
The continuous‐time random walk description of the non‐equilibrium mechanical response of crosslinked elastomers
Authors: Gaylord Richard J. , Joss Brian , Bendler John T. , Dimarzio Edmund A.
Published: April 2007

The application of the continuous‐time random walk model to the description of the non‐equilibrium stress response of a crosslinked network is discussed. Different versions of the continuous‐time random walk model lead to the prediction of a stress relaxation function having either a fractional‐power law form or a fractional‐exponential law form. Both forms are tested against experimental data on the stress relaxation and loss modulus behaviours of crosslinked natural rubber.
Non‐equilibrium mechanical properties of model networks
Authors: Kramer Ole
Published: April 2007

A large number of specially prepared model networks with different types of network defects have been produced since de Gennes proposed the reptation motion for linear chains. The viscoelastic properties of these model networks show clearly that branched chains and dangling chains are the cause of the gradual and extremely slow relaxations in lightly crosslinked networks. These experimental results have been followed by theoretical developments that point towards a complete molecular theory for the non‐equilibrium properties of lightly crosslinked networks. It is proposed that the presence of dangling chains in endlinked networks may be revealed by measurements of the viscoelastic properties of such networks near the transition zone.
Thermoviscoelastic behaviour of EPDM elastomers in chemical and physical networks
Authors: Scholtens Boudewijn J. R.
Published: April 2007

In this study two aspects of the thermoviscoelasticity of EPDM elastomers are discussed, namely their complex behaviour as a result of the presence of (micropara)crystallinity, and the dependence of the time‐temperature shift functions on the crosslink density.
Elasticity of real networks: Comparison of molecular theory with experiments
Authors: Erman Burak
Published: April 2007

Predictions of the theory of elasticity of real networks are compared with results of experiments. The shape of the stress‐strain curve for networks in the dry and swollen states and over wide ranges of strain, both in tension and compression, agrees with results of calculations based on the theory. The theory is also in close agreement with results of multiaxial stress‐strain experiments and with the predictions of the degree of crosslinking obtained from measurements of the modulus. The theory may additionally be applied to the analysis of birefringence. The assumption of the linear additivity of the elastic and mixing free energies in a swollen network leads to results which are in agreement with experimental findings on different crosslinked systems.
Kinetics of gelation of aqueous gelatin solutions
Authors: Djabourov Madeline , Maquet Jean , Theveneau Hélène , Leblond Jacques , Papon Pierre
Published: April 2007

The kinetics of gelation of gelatin + water solutions have been investigated by several experimental methods, in particular optical rotation, 1H nuclear magnetic resonance and rheological measurements. During quenching and isothermal annealing of the solutions, the gelatin chains undergo a conformational coil→helix transition which is responsible for the network growth. The amount of helix (derived from optical rotation measurements) shows a time evolution which could be analysed as the combination of two processes, the first obeying an Avrami equation, the second proceeding logarithmically in time. The water 1H n.m.r. measurements reveal that the spin‐spin relaxation time T2 is affected by these processes, thus implying that a fraction of water contributes to the network structure. Finally, the sol‐gel transition could be followed with a Weissenberg rheogoniometer in oscillatory shear, for a suitable range of temperatures, when the system changes from a purely viscous liquid (the shear modulus G′=0), to an almost purely elastic solid (the loss modulus G″=0).
The elastic behaviour of hydrogels
Authors: Oppermann Wilhelm , Rose Sigrid , Rehage Günther
Published: April 2007

The mechanical properties and the swelling behaviour of aqueous poly(acryl amide) and poly(acryl amide‐co‐Na acrylate) gels were investigated. The ionic networks were prepared by hydrolysis of the nonionic ones, in this way preserving the network topology. By measurement of the modulus it was detected that networks prepared in solution contain a rather large portion of elastically ineffective rings. Hydrolysing a part of the amide groups resulted in a considerably increased swelling ratio. The modulus of such ionic gels did not show the predicted decrease with rising swelling ratio, but on the contrary increased up to a fivefold value. The reason for this behaviour is seen in the limited extensibility (non‐Gaussian behaviour) of the network chains. At constant swelling ratio, the modulus of gels having identical topology decreased with rising degree of hydrolysis. This reflects the influence of the ionic groups on the mean‐square end‐to‐end distance of the free polymer chains.
Formation‐structure relationships in polymer networks
Authors: Dušek Karel
Published: April 2007

The current state of the network formation theory in the pregel and postgel stages of network formation is reviewed. Attention is paid to stochastic and spatial correlations as well as diffusion control of the reaction.
Rate theory of random polymerisation: RA3 polymerisation
Authors: Lloyd Anthony C. , Stepto Robert F. T.
Published: April 2007

The limiting form of rate theory using the first generation subset of states of monomer units is applied to the self‐polymerisation of RA3 monomers. It affords a description of the polymerisation process which specifies how species interconvert. The case of no intramolecular reaction is considered first and it is shown how characteristics of the polymerisation, unit fractions and number fractions of molecular and continuing species, the gel point, the sol fraction and the network at complete reaction, may be evaluated. The gel point is defined in terms of a quantity called the critical total. Intramolecular reaction is then introduced and analytical expressions for the unit fraction of ring structures and for the gel point are derived. They are valid provided the ring‐forming parameter (λ) is not too large. However, in general, numerical evaluation of the characteristics of the polymerisation is required when intramolecular reaction is present. In the paper, emphasis is placed on correlations between the extent of reaction at gelation (Pc) and the structure of the network at complete reaction formed in the presence of pregel and postgel intramolecular reaction. The correlations are compared in general terms with those obtained experimentally for RA2 + RB3 polymerisations.