Showing papers in "Polymer International in 1993"
TL;DR: In this article, a large number of hydrophilic sponges were prepared by polymerisation of 2-hydroxyethyl methacrylate in variable concentrations of water (60-90% wt) in the initial monomer mixture.
Abstract: A large number of hydrophilic sponges were prepared by polymerisation of 2-hydroxyethyl methacrylate in variable concentrations of water (60-90% wt) in the initial monomer mixture. Concentration and type of crosslinking agents (ethylene dimethacrylate (EDMA) and hexamethylene dimethacrylate (HDMA)) and concentration of redox initiators were also changed. All sponges were examined in cross-section by conventional and environmental scanning electron microscopy. Micrographs indicated that, in order to obtain sponges with characteristics appropriate for biomedical use (e.g. pores larger than 10 μm), the minimum water concentration was 75% wt with EDMA as a crosslinking agent, or 70% wt with HDMA, for contents of crosslinking agents and initiator less than 1% wt. Micrographs also showed that higher contents of crosslinking agents or initiator led to larger pores. In high concentrations of water, this effect was less evident. Microscopic details confirmed the crucial role of the phase separation during polymerisation.
122 citations
TL;DR: In this paper, a solution technique modification of polyvinyl alcohol (PVA) using maleic acid was carried out with the help of triethanolamine/water catalysts, and the resulting PVA membranes were characterized by differential scanning calorimetry, infrared spectroscopy, and tensile studies.
Abstract: The ‘solution technique’ modification of poly(vinyl alcohol) (PVA) using maleic acid was carried out with the help of triethanolamine/water catalysts The resulting PVA membranes were characterized by differential scanning calorimetry, infrared spectroscopy, and tensile studies to investigate the reaction between PVA polymer and maleic acid It was found that the resulting PVA membranes had two portions, branched and crosslinked, and there were no more branched than cross-linked portions For the pervaporation separation of the acetic acid-water system, two reaction densities (Xcr = mole maleic acid per mole monomeric unit of PVA) of 005 and 01 were studied for the separation of the entire range of mixture compositions at 25° C The separation factors of the Xcr = 005 modified PVA membranes were higher than those of the Xcr 01 modified ones and the highest separation factor of 780 was obtained at 70wt% water in the feed with the Xcr = 005 modified PVA membrane
82 citations
TL;DR: In this article, the authors used the dynamic swelling method with cooling process to produce monodisperse polystyrene seed particles (1.8 to 7.7 μm diameter) in ethanol/water medium containing styrene monomer, benzoyl peroxide as initiator and polyvinyl alcohol as stabilizer at 65°C.
Abstract: Monodisperse polystyrene particles (6.6 μm diameter) were produced by seeded polymerization utilizing the dynamic swelling method with cooling process as follows. Monodisperse polystyrene seed particles (1.8 μm diameter) were dispersed in ethanol/water (3/4 w/w) medium containing styrene monomer, benzoyl peroxide as initiator and poly(vinyl alcohol) as stabilizer at 65°C. By lowering the temperature to -5°C at a speed of -1°C/min the polystyrene seed particles were swollen from 1.8 to 7.7 μm by the absorption of styrene monomer, keeping the high monodispersity. An appropriate amount of water was then added to the dispersion at -5°C to depress the redissolution of styrene from the swollen particles into the medium
73 citations
TL;DR: Methods for preparation of monosized polymer particles are described and the most important biochemical and biomedical applications of various types of particless, including magnetic particles, are given.
Abstract: Methods for preparation of monosized polymer particles are described and the most important biochemical and biomedical applications of various types of particless, including magnetic particles, are given
60 citations
TL;DR: In this article, the authors measured the kinetics of formation of the polyvinyl alcohol (PVA) intermediate complex using a spectrophotometric technique and found that the rate of formation is dependent on the base concentration.
Abstract: The kinetics of formation of the [PVA. MnVIO] intermediate complex have been measured by the conventional spectrophotometric technique. The rate of formation of the complex was found to be given by the expression d[Complex]/dt = k1[MnO-4][PVA−]. The results showed that the rate of formation is dependent on the base concentration. A first-order reaction in permanganate and fractional order with respect to the poly(vinyl alcohol) (PVA) concentration were observed. The activation parameters have been evaluated and a tentative reaction mechanism has been suggested.
59 citations
TL;DR: In this paper, the brittle-ductile transition in polymer blends seems to be a universal percolation phenomenon, and the critical exponent (g) is found to be 0.83 for HDPE/CaCO3 blends.
Abstract: The percolation model is used to interpret the brittle-ductile transition of HDPE/CaCO3 blends. The percolation threshold (θsc) for HDPE/CaCO3 blends is found to be 0.52, which is equal to π/6. The critical exponent (g) is found to be 0.83 for HDPE/CaCO3 blends. The toughening efficiency of blends which have monodisperse, highly asymmetrical particles, strong interphase adhesion and high matrix toughness is greater. The brittle-ductile transition in polymer blends seems to be a universal percolation phenomenon.
52 citations
TL;DR: In this article, the crystal structure of Nylon-1010 was determined from X-ray diffraction patterns of uniaxially oriented fibres, based upon a one-dimensional electron-density correlation function.
Abstract: WAXD, SAXS, FTIR, DSC and density techniques have been used to investigate the crystal structure, crystal density rho(c), amorphous density rho(a), equilibrium heat of fusion DELTAH(m)degrees and equilibrium melting temperature T(m)degrees. By extrapolating the straight lines in the FTIR absorbance against density plot to zero intensity, rho(c) and rho(a) were estimated to be 1.098 and 1.003 g/cm3 respectively. The rho(c) obtained was too low in value. From X-ray diffraction patterns of uniaxially oriented fibres, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallized in the triclinic system, with lattice dimensions: a = 4.9 angstrom, b = 5.4 angstrom, c = 27.8 angstrom, alpha = 49-degrees, beta = 77-degrees, gamma = 63.5-degrees. The unit cell contained one monomeric unit, the space group was P1BAR, and the correct value of rho(c) was 1.135 g/cm3. The degree of crystallinity of the polymer was determined as about 60% (at RT) using Ruland's method. SAXS has been used to investigate the crystalline lamellar thickness, long period, transition zone, the specific inner surface and the electron density difference between the crystalline and amorphous regions for Nylon-1010. The analysis of data was based upon a one-dimensional electron-density correlation function. DELTAH(m)degrees was estimated to be 244.0 J/g by extrapolation of DELTAH(m)degrees in the plot of heat of fusion against specific volume of semicrystalline specimens to the completely crystalline condition (V(sp)c = 1/rho(c)). Owing to the ease of recrystallization of melt-crystallized Nylon-1010 specimens, the well-known Hoffman's T(m)-T(c) method failed in determining T(m)degrees and a Kamide double extrapolation method was adopted. The T(m)degrees value so obtained was 487 K.
50 citations
TL;DR: Differential scanning calorimetry (DSC) was employed to examine the thermally initiated and catalysed polymerizations of a number of cyanate ester monomers in this article.
Abstract: Differential scanning calorimetry (DSC) was employed to examine the thermally initiated and catalysed polymerizations of a number of cyanate ester monomers. Rigorous purification by preparative HPLC was found to have marked effects on the thermal polymerization characteristics of these compounds as determined by DSC. The effects on the thermal behaviour of varying the heating rate and level of catalysis were also examined. The thermal polymerization of the cyanate ester monomers was found to obey a first order model over wide apparent conversion limits. Functionalized cyanate ester/bis-maleimide copolymers were prepared and the thermal stabilities of these were evaluated by thermogravimetric analysis (TGA) alongside a variety of commercial blends and homopolymers. The dynamic mechanical properties of the cured neat resins were also investigated.
46 citations
TL;DR: In this article, the applicability of the three-component solubility parameter approach by Paine was examined and the size of the microspheres varied from 0.2 to 1.3 μm as a function of the solubilities parameter of the dispersants.
Abstract: Monodisperse hydrogel microspheres were prepared by precipitation polymerization of acrylamide and comonomers in ethanol and propan-2-ol and their mixtures. The size of the microspheres varied from 0.2 to 1.3 μm as a function of the solubility parameter of the dispersants. The applicability of the three-component solubility parameter approach by Paine was examined. Seeded polymerization of styrene using the seed microspheres mentioned above yielded unique composite microspheres whose surface property changed gradually with the content of styrene
41 citations
TL;DR: In this article, side-chain liquid crystalline polymers with laterally attached mesogenic group were synthesized and some of the polymers showed nematic phase, and polyoxetanes having mesogen with electron-withdrawing and electron-donating groups in the molecule showed a little more discrete mesophase.
Abstract: Side-chain liquid crystalline polymers with laterally attached mesogenic group were synthesized. Polymers having polyoxetane main chain were obtained by cationic polymerization, and with polymethacrylate main chain by radical polymerization. Some of the polymers showed nematic phase, and polyoxetanes having mesogen with electron-withdrawing and electron-donating groups in the molecule showed a little more discrete mesophase.
40 citations
TL;DR: In this article, a thermodynamic analysis and a mathematical model were developed to describe the free energy changes corresponding to various possible morphologies in composite latex particles and two experimental composite latex systems were used to verify and establish limitations of the model.
Abstract: A thermodynamic analysis and a mathematical model were developed to describe the free energy changes corresponding to various possible morphologies in composite latex particles Two experimental composite latex systems were used to verify and establish limitations of the model The two latex systems were based on polystyrene/poly(methyl methacrylate), one prepared by conventional seeded emulsion polymerization and the second system by direct emulsification of a solution of a blend of the two polymers The influence of several experimental parameters on latex particle morphology was investigated These included monomer/polymer ratio, surfactant type, and initiator type in the seeded emulsion polymerization system The influence of local viscosity, shear effects, and molecular weights of polymers were investigated in the artificial latex system
TL;DR: In this paper, the application of a continuous Couette-Taylor vortex reactor to continuous emulsion polymerization was studied and the mixing characteristics of the reactor were examined by the stimulus-response method.
Abstract: The application of a continuous Couette-Taylor vortex reactor to continuous emulsion polymerization was studied. First, the mixing characteristics of the reactor were examined by the stimulus-response method. It was found that the reactor performance was similar to that of a continuous flow reactor consisting of more than 60 well-stirred tanks in series if the reactor was properly designed and operated near the critical Taylor number. It was also shown by a comparison of the particle size distributions of the latices produced in a batch reactor and in the continuous Couette-Taylor vortex that the continuous reactor could produce latex particles with fairly narrow size distribution
TL;DR: An improved version of a novel method first employed by Nagy & Keller for the preparation of monodisperse ellipsoidal polystyrene latex particles is described in this article, where the method involves embedding a spherical poly styrene latex particle as starting material in a deformable polymer matrix such as poly(vinyl alcohol) and deforming these mechanically to various predetermined macroscopic draw ratios to give ellipssoids of various axial ratios.
Abstract: An improved version of a novel method first employed by Nagy & Keller for the preparation of monodisperse ellipsoidal polystyrene latex particles is described. The method involves embedding monodisperse spherical polystyrene latex particles as starting material in a deformable polymer matrix such as poly(vinyl alcohol) and deforming these mechanically to various predetermined macroscopic draw ratios to give ellipsoids of various axial ratios. Ellipsoids with lengths ranging from about 350 to 12 250 nm were prepared. Stable aqueous dispersions of these were recovered and characterized with respect to particle size and axial ratio distribution and surface morphology
TL;DR: The diphenol-substituted polystyrene condensation macromonomers have been characterized by end-group titration, size exclusion chromatography, thin-layer chromatography and ultraviolet-visible, 1H and 13C NMR spectroscopy as mentioned in this paper.
Abstract: ω,ω-Diphenolpolystyrenes (6) can be synthesized in quantitative yields by reacting poly(styryl)lithium with 1,1-bis(4-t-butyldimethylsiloxyphenyl)ethylene (1), followed by methanol termination and hydrolysis with dilute acid. The initially formed 1,1-bis(4-t-butyldimethylsiloxyphenyl)alkyllithium can be reacted with additional styrene monomer to form a polystyrene internally substituted with two in-chain phenol groups after methanol termination and acid hydrolysis. The diphenol-substituted polystyrene condensation macromonomers have been characterized by end-group titration, size exclusion chromatography, thin-layer chromatography, and ultraviolet-visible, 1H and 13C NMR spectroscopy. Chain-extension reactions of 6 (Mn = 2.6 × 103g mol−1) with bis(trichloromethyl)carbonate produced the corresponding comb-type, branched polymer with estimated Mn(SEC, polystyrene standards) = 1.2 × 104g mol−1 and no detectable residual condensation macromonomer. The second order rate constants for the addition reaction of excess poly(styryl)lithium with 1 and with 1-(4-t-butyldimethylsiloxy-phenyl)-1-phenylethylene (3) have been estimated to be 1.7 × 10−3M−1/2S−1 and 3.2 × 10−3M−1/2S−1 respectively. A sigma value (σ) of −0.46 has been estimated for the t-butyldimethylsiloxy substituent.
TL;DR: In this paper, the effects of microstructuring induced by KrF-laser (248 nm) radiation on PET (poly(ethylene terephthalate) film surfaces were investigated.
Abstract: The effects on chemical and physical properties of PET (poly(ethylene terephthalate)) film surfaces as a result of microstructuring induced by KrF-laser (248 nm) radiation were investigated. On irradiation, the properties of film surfaces changed in proportion to radiation flux intensity. Close to threshold values, bulbous swellings appeared on the surface, which showed hydrophilic properties. At the threshold and above, regular rippling was seen, and the surface showed hydrophobic properties. Excimer laser irradiation induced chemical modification of the surface, decrease in the O/C ratio, dissociation of ester binding and amorphism as observed by X-ray-induced photoelectron spectroscopic and Fourier-transform infrared analysis.
TL;DR: In this article, a poly(N-isopropylacrylamide) (PNIPAM) hydrogel microspheres were prepared by precipitation polymerization above the polymer's LCST in water.
Abstract: Poly(N-isopropylacrylamide) (PNIPAM) hydrogel microspheres were prepared by precipitation polymerization above the polymer's LCST in water. The hydrodynamic size of PNIPAM microspheres exhibited a thermo-sensitive change around the LCST. In order to obtain information about the interface of the hydrogels, contact angle measurement, protein adsorption, and fluorescence analysis were performed. The results led to the conclusion that the surface of the thermosensitive hydrogel microsphere become hydrophobic above the LCST in conjunction with its volume transition. This can be explained by association of segments induced by the hydrophobic interaction above the LCST.
TL;DR: This paper-like cellulosic support is a potential matrix for bioseparators, bioreactors and affinity chromatography, and the IgG binding profiles of Immunoglobulins of the G class and immobilised proteins A and G were similar.
Abstract: The suitability of a new paper-like cellulosic rod as a support for the immobilisation of proteins has been studied as an alternative to the common, beaded supports. α-Amylase was covalently immobilised on to this paper-like cellulosic support using cyanogen bromide and 1,1′-carbonyldiimidazole activation procedures. The enzymic activity of α-amylase immobilised onto the activated support was measured by the initial rate of hydrolysis of starch. During the first three successive assays 60-70% of the initial activity of the immobilised α-amylase was lost (possibly due to non-specific adsorption of the protein), then becoming stable. This enzymic activity was retained after long storage periods. The amounts of enzyme bound to cyanogen bromide and 1,1′-carbonyldiimidazole-activated supports, calculated from the specific catalytic activity of α-amylase, were 0.52 and 0.59μgg−1 respectively. Proteins A and G were also coupled to the cellulosic support using 1,1′-carbonyldiimidazole. The amounts of proteins A and G bound to the activated support, determined spectrophotometrically at 260 and 280nm, were 2.33 and 0.31 mg g−1, respectively. The binding between various radiolabelled immunoglobulins of the G class and immobilised proteins A and G were examined. The IgG binding profiles of immunophilic proteins coupled to paper-like cellulosic rod and to commercially available beaded supports were similar. Therefore, this paper-like cellulosic support is a potential matrix for bioseparators, bioreactors and affinity chromatography.
TL;DR: In this paper, modified polyvinyl alcohol (PVA) membranes were tested for ethanol-water mixtures by varying the reaction density (Xcr = 0.05, 0.1) at various temperatures.
Abstract: Modified poly(vinyl alcohol) (PVA) membranes prepared by the ‘solution technique’ were tested for ethanol-water mixtures by varying the reaction density (Xcr = 0.05, 0.1) at various temperatures. The results are compared with those of PVA membranes (Xcr = 0.05) prepared by the technique of the GFT Company, Germany.
TL;DR: In this paper, a monodisperse poly(methyl methacrylate) (PMMA) particle was prepared by dispersion copolymerization of MMA with a hydrophilic poly(2-oxazoline) macromonomer in an aqueous methanol solution.
Abstract: Micron-size monodisperse poly(methyl methacrylate) (PMMA) particles were prepared by dispersion copolymerization of MMA with a hydrophilic poly(2-oxazoline) macromonomer in an aqueous methanol solution. The macromonomer acted as a comonomer as well as a stabilizer. As the macromonomer concentration increased, the diameter of the particles decreased. The macromonomer with higher molecular weight, or with more hydrophilic nature, stabilized the particles more effectively. The diameter of the particles was dependent on the initiator concentration
TL;DR: In this paper, the influence of thermoplastic polyurethane (TPU) elastomer on the rigidity of polyacetal (polyoxymethylene, POM) was studied by determining heat deflection temperature (HDT).
Abstract: The influence of thermoplastic polyurethane (TPU) elastomer on the rigidity of polyacetal (polyoxymethylene, POM) was studied by determining heat deflection temperature (HDT). The higher the content of TPU in the POM/TPU blend, the lower the HDT of the blend, as would be expected. A comparative study of the recycle capability of POM and the blends was carried out by measuring melt flow index (MFI) on each successive extrusion. Stress-strain behaviour of the virgin material and that obtained after fourth-time extrusion was analysed for POM and the blends. The effect of γ-radiation on the mechanical behaviour of the blends was investigated. The kinetics of thermal degradation of POM, TPU and their blends was studied. The kinetic parameters, viz. activation energy and the order of reaction, were established. The values of the activation energy of the blends were found to be higher than those of the POM and TPU, indicating improved stability of the resultant blends.
TL;DR: In this paper, the effects of the polymerization method on the thermal and mechanical properties of TPUs have been studied from thermal and tensile property measurements, compared with those prepared by the prepolymer method.
Abstract: Thermoplastic polyurethane elastomers (TPUs) based on 4,4′-methylene-diphenyl diisocyanate, poly(tetramethylene glycol), diamine-terminated aliphatic nylon oligomer, and 1,4-butanediol were synthesized by two different polymerization methods, i.e. one shot and prepolymer methods. The effects of the polymerization method on the thermal and mechanical properties of the TPUs have been studied. A broader distribution of hard segment lengths in TPUs prepared by the one shot method was observed from thermal and tensile property measurements, compared with those prepared by the prepolymer method. TPUs by the one shot method showed a higher Tm of the hard segments and better tensile properties when soft-hard segment interaction was relatively small. However, inferior tensile properties were observed when the soft-hard segment interaction was high; typically when nylon oligomer was used as a soft segment.
TL;DR: In this paper, the kinetics of decomposition of [PVA] intermediate complex have been studied spectrophotometrically and a first-order dependence on the intermediate concentration was observed.
Abstract: The kinetics of decomposition of [PVA. Mn VI O 4 2- ] intermediate complex have been studied spectrophotometrically. A first-order dependence on the intermediate concentration was observed. The decomposition rate was found to be base-catalysed. The kinetic parameters have been evaluated and a mechanism consistent with the results obtained is discussed
TL;DR: In this article, the phase separation of different copolyesters of lactides and glycolide solutions induced by the addition of silicone oil in order to promote microencapsulation of proteins is discussed.
Abstract: This paper is related to the phase separation of different copolyesters of lactides and glycolide solutions induced by the addition of silicone oil in order to promote microencapsulation of proteins. This coating process can be divided in three successive steps: phase separation of the coating polymer; adsorption of the coacervate droplets around the drug phase, and microcapsule solidification. This paper focuses on the physico-chemical analysis of the second step. The knowledge of the interfacial tensions between the three liquid phases allows understanding of the microscopic evolution of the phase separation medium.
TL;DR: In this article, a series of polyaniline dispersions were prepared by oxidative polymerization of aniline in aqueous medium using ammonium persulfate as an oxidizing agent and polyvinyl alcohol as a steric stabilizer of dispersions.
Abstract: Several series of polyaniline dispersions were prepared by oxidative polymerization of aniline in aqueous medium. Ammonium persulfate was used as an oxidizing agent and poly(vinyl alcohol) as a steric stabilizer of dispersions. The amount of dispersion particles, their size and uniformity, and the fraction of the steric stabilizer attached to the particles were determined in dependence on the concentration of the individual components and on temperature. The properties of resulting dispersions are controlled mainly by the concentration of the oxidizing agent and by the polyaniline/stabilizer ratio
TL;DR: In this paper, a non-planar geometrical structure for chelation between functional groups and the interdiffused metal ions has been suggested, as well as a planar geometry for the divalent and hexavalent metal alginates.
Abstract: Electrical conductance measurements showed that monovalent, trivalent and tetravalent metal alginate complexes possess electrical conductivities in the order of semiconductors, whereas divalent and hexavalent metal alginate electrical conductivities lic in the range of insulators. X-Ray diffraction indicated that these metal alginate complexes are amorphous in nature. Two geometrical structures for chelation between the functional groups and the interdiffused metal ions have been suggested: a non-planar geometrical structure for the mono-, tri- and tetravalent metal alginates, and a planar geometry for the divalent and hexavalent metal alginates.
TL;DR: In this article, the electrochemical behavior, FTIR spectrum and morphology of polypyrrole-polystyrenesulphonate (PPy-PSS) films obtained potentiostatically at 0.6 V in a 0.05m Py + 1.7 × 10−2m NaPSS medium have been analyzed.
Abstract: The electrochemical behaviour, FTIR spectrum and the morphology of polypyrrole-polystyrenesulphonate (PPy-PSS) films obtained potentiostatically at 0.6 V in a 0.05m Py + 1.7 × 10−2m NaPSS medium have been analysed. Different electrochemical parameters have been modified in order to establish the first polaron formation, the reversibility of the redox process and the doping mechanism.
The FTIR spectrum confirms the existence of CO groups in the film structure and two possible explanations are suggested. SEM reveals a higher homogeneity in these films than in PPy films doped with smaller counterions.
TL;DR: In this article, reaction-induced phase separation in epoxy systems modified with rubber was firstly observed in situ with small angle X-ray scattering (SAXS), light transmission (LT), light scattering (LS), scanning electronic microscopy and transmission electron microscopy techniques, and different observation windows of the SAXS, LT and LS methods allow us to follow the phase separation at two size levels.
Abstract: The reaction-induced phase separation in epoxy systems modified with rubber was firstly observed in situ with small angle X-ray scattering (SAXS), light transmission (LT), light scattering (LS), scanning electronic microscopy and transmission electronic microscopy techniques. The different observation windows of the SAXS, LT and LS methods allow us to follow the phase separation at two size levels. The selected system was bisphenol-A diglycidylether cured with 4,4′-diamino-3,3′-dimethyldicyciohexylmethane, in the presence of 15% wt of epoxy-terminated butadiene acrylonitrile random copolymers of different molecular weights. The phase separation inside the particles formed was followed first. Influences of precure temperature, rubber molecular weight, the postcure, vitrification and gelation on the evolution of the structure inside the particles are discussed. The real beginning of the phase separation is also discussed.
TL;DR: In this article, three 4-hydroxyphenylmaleimide/n-butylacrylate copolymers with different monomer ratios were synthesized and their average molecular weights, glass transition temperatures (T,g), and thermal decomposition temperatures were measured.
Abstract: Three 4-hydroxyphenylmaleimide/ n-butylacrylate (HPMI/n-BuA) copolymers with different monomer ratios were synthesized Their average molecular weights, glass transition temperatures (T,g), and thermal decomposition temperatures were measured It was found that these copolymers had higher average molecular weights and higher thermal decomposition temperatures than novolac
Modified phenolic resins were prepared by transfer moulding from moulding compounds consisting of novolac, the copolymer, hexamethylenetetramine (hexamine), and glass fibre Properties of the three kinds of modified phenolic resins were examined by flexural test, impact test, dynamic thermomechanometry, and observation of morphology It was found that phenolic resin modified with HPMI/ n-BuA (1/3-6) copolymer and modified with HPMI/n-BuA (1/7-0) copolymer showed good toughness and good heat resistance It was also found that the heat resistance of modified phenolic resins was improved by after-cure, but the mechanical properties were decreased by after-cure: similar behaviour was observed for unmodified phenolic resin
TL;DR: The results of the sorption and diffusion of aldehydes and ketones into structurally different elastomers such as ethylene propylene diene terpolymer, styrene butadiene rubber, nitrile and neoprene and natural rubber are described in the temperature interval of 25-60°C as mentioned in this paper.
Abstract: The results of the sorption and diffusion of aldehydes and ketones into structurally different elastomers such as ethylene propylene diene terpolymer, styrene butadiene rubber, nitrile butadiene rubber, neoprene and natural rubber are described in the temperature interval of 25-60°C. From these data, the Arrhenius parameters for the processes of diffusion and permeation are determined. The activation parameters for the diffusion of ketones range from 10.29 to 49.62 kJ/mol and for aldehydes, from 13.18 to 50.42 kJ/mol; these values fall in the range expected for rubbery polymers well above their glass transition temperatures. Transport data are affected by the nature of the interacting solvent molecule rather than its size and also by the structural variations of the elastomers. For all the solvents, the polymers remained intact; however, natural rubber in the presence of benzaldehyde showed degradative reactions at higher temperatures. Volumetric expansions of the elastomers have been measured from the dimensional response in the presence of aggressive solvents.