Polymer Gels and Networks最新文献

{"title":"Non-linear constitutive equations for viscoelastic behaviour of elastomers at large deformations","authors":"G. Spathis","doi":"10.1016/0966-7822(95)00031-3","DOIUrl":"10.1016/0966-7822(95)00031-3","url":null,"abstract":"<div><p>A non-linear theory of viscoelasticity for large deformation of elastomers has been developed. The concept of an internal variable stress which is governed by a rate equation, has been used to account for the viscoelastic behaviour of incompressible rubbers. Following a molecular approach the parameters of the model were extracted by the inverse Langevin approximation of rubber elasticity. Qualitative applications were made in the case of uniaxial elongation and simple shear deformations.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 1","pages":"Pages 55-68"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0966-7822(95)00031-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73133361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A note on the selectivity of γ-radiation polymerised molecularly imprinted poly (HEMA)","authors":"K. Sreenivasan","doi":"10.1016/S0966-7822(96)00027-5","DOIUrl":"10.1016/S0966-7822(96)00027-5","url":null,"abstract":"<div><p>γ-radiation was used to synthesise molecularly imprinted poly (2-hydroxy ethyl methacrylate) containing memory sites for testosterone. The high degree of selectivity of the polymer towards testosterone has been demonstrated by studying the interaction of the polymer with a mixture of testosterone and cholesterol, a molecule with a similar ring structure and shape as testosterone.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 1","pages":"Pages 17-22"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(96)00027-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87571995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Swelling of poly-L-lysine and chitosan-coated superswelling sodium-alginate gel beads","authors":"Mette H. Ottøy ,&nbsp;Olav Smidsrød","doi":"10.1016/S0966-7822(97)00003-8","DOIUrl":"10.1016/S0966-7822(97)00003-8","url":null,"abstract":"","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 3","pages":"Pages 307-314"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(97)00003-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86261621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relaxation of stress and orientation in thermo-reversible networks","authors":"Alexander Dardin ,&nbsp;Hans W. Spiess ,&nbsp;Reimund Stadler ,&nbsp;Edward T. Samulski","doi":"10.1016/S0966-7822(96)00030-5","DOIUrl":"10.1016/S0966-7822(96)00030-5","url":null,"abstract":"<div><p>4-(3,5-dioxo-1,2,4-triazolidin-4-yl) benzole (U4A) or -isophthalic acid (U35A) units randomly attached to a polybutadiene backbone form extended supramolecular hydrogen bond assemblies, which act as effective junction zones in unusual thermoreversible elastomer networks. The relaxation behavior of stress and the segmental orientation induced after a sudden strain, has been investigated by means of step-strain experiments and ²H-NMR spectroscopy.</p><p>The stress relaxation behavior can be described as a two-step process in which the first step is very sensitive to the stability of the supramolecular aggregates. About 20 s after reaching the initial strain, stress is reduced to a value comparable to the yield-stress in stress-strain cycles. The long-time relaxation behavior is interpreted as a reduction of the effective cross-link density due to a gradual breakdown of the hydrogen bond clusters. The relaxation data of the functionalized polybutadienes can be superimposed to give master curves, which are characteristic for the type of junction zone. The degree of aggregate degradation is estimated as a function of the initial stress.</p><p>In the same type of step-strain experiment, the ²H-NMR spectra show a decay of the line splitting as well as a change in the complete lineshape.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 1","pages":"Pages 37-54"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(96)00030-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82786656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polyampholyte gels: swelling, collapse and interaction with ionic surfactants","authors":"Le Thi Minh Thanh,&nbsp;E.E. Makhaeva,&nbsp;A.R. Khokhlov","doi":"10.1016/S0966-7822(97)00006-3","DOIUrl":"10.1016/S0966-7822(97)00006-3","url":null,"abstract":"<div><p>Two series of polyampholyte gels formed from sodium methacrylate and diallyldimethylammonium chloride with variable composition were synthesized in water and in aqueous salt solution. It is shown that the swelling properties of polyampholyte gels are directly related to their chemical structure, which is defined by the process of gel synthesis. The swelling ratio of the polyampholyte gels prepared in salt solution is large compared with the gels prepared in pure water i.e. the polyampholyte gels with balanced stoichiometry show minimal swelling.</p><p>The interaction of the polyampholyte gels with ionic surfactants (cationic, cetylpyridinium chloride and anionic, sodium dodecylbenzenesulphonate) was studied. It was shown that for polyampholyte gels with an excess of the charges of one sign the addition of oppositely charged surfactant leads to the collapse of the gel. It was found that the efficiency of surfactants absorption is determined by the ratio of positive and negative charges in the chains of polyampholyte gels.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 4","pages":"Pages 357-367"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(97)00006-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74537188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aggregation behaviour below the gelation threshold for metal-olefin coordination in diene polymers","authors":"Francis Bossé,&nbsp;Pronab Das,&nbsp;Laurence A. Belfiore","doi":"10.1016/S0966-7822(97)00009-9","DOIUrl":"10.1016/S0966-7822(97)00009-9","url":null,"abstract":"<div><p>This study focuses on aggregation below the gelation threshold in ternary solutions containing diene polymers, atactic 1,2-polybutadiene (PBu) or 3,4-polyisoprene (PI), and an inorganic salt, bis(acetonitrile) dichloropalladium(II). Upon mixing, effective coordination crosslinks are formed because the acetonitrile ligands of the palladium salt are displaced by olefinic pendant groups of the polymers. In all cases, the aggregation kinetics correlate with PdCl₂ concentration because the polymer concentration is 100 times greater than the salt concentration. Aggregation is the process that occurs prior to gelation as the transition-metal salt forms a coordination bridge between two different polymer chains. Differential analysis of the initial aggregation rate on the basis of light scattering data at 45° relative to the incident throughput beam reveals that the ‘true’ order of the coordination reaction is close to unity. This suggests that coordination crosslinking is diffusion-controlled in the early stages of aggregation. Half-life analysis of viscous solutions yields an overall reaction order of 1.6 for aggregation of polybutadiene and palladium chloride in tetrahydorfuran (THF). Scaling analysis of the weight-average molecular weight dependence of the root-mean-square size of isolated scattering particles yields an effective exponent of 0.7 for polymer/metal-salt complexes at infinite dilution. This experimental scaling law agrees with literature values for cross-linked polymer networks. In all cases, the size of the aggregates increases at higher PdCl₂ concentration. For polybutadiene/PdCl₂ mixtures in THF or toluene below the gelation threshold, the light-scattering-detected average aggregation number (AN = M_{w, complex}/M_{w, pure polymer} via Zimm-plot intercepts) for low-viscosity solutions is 2, while AN ∼ 9 for viscous THF solutions. In contrast, low aggregation numbers (AN ∼ 2) were calculated for viscous ternary mixtures of 3,4-polyisoprene and PdCl₂ in THF.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 5","pages":"Pages 387-413"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(97)00009-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78830238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calendar85","authors":"","doi":"10.1016/S0966-7822(97)90008-3","DOIUrl":"https://doi.org/10.1016/S0966-7822(97)90008-3","url":null,"abstract":"","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 4","pages":"Page 385"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(97)90008-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"137143375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Swelling behavior of a blend hydrogel made of poly(allylguanidino-co-allylamine) and poly(vinyl alcohol)","authors":"Kokoro Iio,&nbsp;Norihiko Minoura","doi":"10.1016/S0966-7822(97)00001-4","DOIUrl":"10.1016/S0966-7822(97)00001-4","url":null,"abstract":"<div><p>A hydrogel was prepared by mixing poly(allylguanidino-co-allylamine) hydrochloride (PAG) with poly(vinyl alcohol) (PVA) and repeatedly freezing and thawing the blend. The swelling behavior of the hydrogel was investigated as a function of the pH and ionic strength of the medium. In a salt-free aqueous medium, a size of the hydrogel was reduced below pH 3 and above pH 10, but the size was little affected in the pH range 3 ≈ 10. In a medium of constant ionic strength (μ = 0.1), the hydrogel's pH response was different: it was significantly reduced in size above pH 9, but the size was affected only moderately below pH 9. When the ionic strength of medium was varied at a fixed pH, the size change of the hydrogel was gradual. All these phenomena could be understood by observing that PAG displayed multiple protonation states due to pH and that the electrostatic interactions among the charges on the polymer backbone are shielded by the added electrolyte as the ionic strength of the medium is raised.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 4","pages":"Pages 317-326"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(97)00001-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85387138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence for a conformational transition in curdlan","authors":"Masakuni Tako,&nbsp;Isao Hanashiro","doi":"10.1016/S0966-7822(96)00036-6","DOIUrl":"10.1016/S0966-7822(96)00036-6","url":null,"abstract":"<div><p>Gelation occurred at a concentration of 0.3% curdlan solution at room temperature (25 °C). The curdlan showed a Newtonian behavior at 0.1%, but plastic behavior above 0.2% even at a temperature of 38 °C. The dynamic modulus remained at a constant value with an increase of temperature up to 40 °C., which was estimated to be a transition temperature, then it decreased rapidly with an increase of temperature until 55 °C; however, it increased gradually with a further increase of temperature. The dynamic viscoelasticity of curdlan solution remained at very low values on addition of urea (4 M) and decreased with increasing temperature. The optical rotation of curdlan (0.1%) increased with a decrease of temperature.</p><p>Possible modes of intra- and intermolecular hydrogen bonding within and between curdlan molecules were proposed. A hydrophobic interaction might take place at high temperatures (&gt;55 °C), the mode of which was also proposed.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 3","pages":"Pages 241-250"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(96)00036-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85345969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The gel point as reference state: A simple kinetic model for crosslinking polybutadiene via hydrosilation","authors":"Michael E. De Rosa ,&nbsp;Marian Mours ,&nbsp;H.Henning Winter","doi":"10.1016/S0966-7822(96)00033-0","DOIUrl":"10.1016/S0966-7822(96)00033-0","url":null,"abstract":"<div><p>Kinetic data can be described in a simple model when using the gel point as reference state. This has been shown for crosslinking data on five high molecular weight polybutadienes (18 100–97 000 g/mol). Experiments were carried out under isothermal conditions with a constant amount of catalyst. Crosslinking took place by a hydrosilation reaction at vinyl sites which were randomly distributed along the backbone of the polybutadiene precursor molecules using the bifunctional aromatic silane p-bis(dimethylsilyl) benzene as connector. FTIR measurements showed that the hydrosilation reaction followed first order kinetics. The critical gel time, t_c, was determined by the instant at which power law relaxation behavior was observed (i.e. tan δ = constant) over the two lowest decades in frequency. The main parameters that were observed to affect t_c were the stoichiometric ratio, r, and the functionality of the polybutadiene, f. It was observed that the time to reach the gel point decreased with increasing precursor molecular weight (~f) of the polybutadiene. The gel time also decreased when increasing the initial amount of silane crosslinker. We were able to find a relationship between the gel time measured by the CFS technique and r and f by coupling the Flory-Stockmayer gelation theory with a simple first order kinetic curing scheme.</p></div>","PeriodicalId":20331,"journal":{"name":"Polymer Gels and Networks","volume":"5 1","pages":"Pages 69-94"},"PeriodicalIF":0.0,"publicationDate":"1997-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0966-7822(96)00033-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78774033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}