Zur unverträglichkeit von polymergemischen V. Lichtstreuungsmessungen an hochmolekularem polystyrol und poly-α-methylstyrol in polybutadien/benzol und polyisoprene/benzol

Results are reported on incompatibility measurements of a high molecular weight polystyrene of poly-α-methylstyrene in the isorefractive polymer solvent mixtures polybutadiene/benzene and polyisoprene/benzene respectively by means of the light scattering method. It turns out that polystyrene in cis-1,4-polybutadiene/benzene mixtures is more incompatible as in configurationally non-uniform polybutadiene/benzene mixtures. Furthermore the measurements showed that the incompatibility of polystyrene with cis-1,4-polybutadiene and with cis-1,4-polyisoprene is practically identical. Whereas the degree of incompatibility of polystyrene and poly-α-methylstyrene with polybutadienes in benzene is also nearly the same the incompatibility of polystyrene with cis-1,4-polyisoprene/benzene however is much greater than with poly-α-methylstyrene. An empirical interpretation of these and of former results on other polymer system is discussed.     

Zur unverträglichkeit von polymergemischen. 1. Lichtstreuungsmessungen am system polystyrol/polymethylmethacrylat/benzol

A polystyrene (PS) with M?_w = 9,7 · 10⁴ was investigated by means of light scattering in the isorefractive polymer/solvens-mixture polymethylmethacrylate (PMMA)/benzene. It was found, that the second osmotic virial coefficient A₂ of PS was strongly dependent on the average viscosimetric molecular weight M?_v and on the concentration of PMMA, but scarcely on the temperature in the range of 20°C to 60°C. The θ-Point, where A₂ is zero, was independent of the temperature within experimental error. By defining the PMMA concentration at the θ-Point as c_θ, and by reducing the measured PMMA concentration c to c/c_θ, an unequivocal relation was obtained between A₂ and c/c_θ, which is independent of molecular weight and molecular weight distribution of PMMA. PS shows a high second virial coefficient in dimer and trimer MMA as well as in non-hydrogenated and hydrogenated MMA. The investigated PS constitutes a θ-System in PMMA of a degree of polymerisation of P?_w, ～ 17without the use of benzene.     

Effect of γ‐irradiation on the physical properties and dyeability of poly(vinyl butyral) blends with polystyrene and poly(ethylene glycol)

Cast films of polymer blends essentially based on poly(vinyl butyral) (PVB) and equal ratios of polystyrene (PS) and poly(ethylene glycol) (PEG) were prepared from benzene and butyl alcohol solutions of the individual polymers. The effect of γ‐irradiation on the thermal decomposition and tensile mechanical properties was investigated. Moreover, the effect of γ‐irradiation on the dye affinity of PVB/PS and PVB/PEG for basic and acid dyestuffs was studied. The thermogravimetric analysis (TGA) study showed that the unirradiated PVB polymer films prepared in benzene displayed higher thermal stability than the same polymer films prepared in butanol. However, in all cases the thermal stability was found to increase with increasing γ‐irradiation dose. On the other hand, PVB/PS blend possesses higher thermal stability than PVB/PEG, as shown from the determination of the weight loss (%) at different heating temperatures, the temperatures of the maximum rate of reaction and the activation energy. While, pure PS films showed the stress‐strain behavior of brittle polymers, PVB/PS films showed the behavior of tough polymers with yielding properties. The results of dyeing clearly showed that the solvent type, blend composition, and irradiation dose are determining factors for the dye affinity for basic or acid dyes. For example, unirradiated PVB films prepared from butanol displayed a higher affinity for the basic and acid dyes than the same polymer prepared from the same benzene. However, PVB prepared from butanol showed higher affinity to the dyes than PS prepared from the same solvent. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Zur unverträglichkeit von polymergemischen IV. Lichtstreuungsmessungen an hochmolekularem poly-α-methylstyrol in polymethylmethacrylat/benzol

High molecular weight Poly-α-methylstyrene was investigated by means of light scattering in the isorefractive polymer/solvent mixture Polymethylmethacrylate/benzene. The dependence of the scattering on the concentrations could be interpreted theoretically in terms of the Stockmayer light scattering theory for multicomponent systems. It turns out that Poly-α-methylstyrene is essentially more compatible in Polymethylmethacrylate/benzene compared with polystyrene. This is valid not only in solution but also in the solid state. In agreement with this better compatibility the decrease in the radii of gyration of the poly-α-methylstyrene is less pronounced than that of the radii of the polystyrene if polymethylmethacrylate is added.     

Kirkwoodsche Korrelationsfaktoren von binären Systemen mit Alkoholen und Diäthyläther

Kirkwood Correlation Factors of Binary Systems with Alcohols and Diethylether The KIRKWOOD theory allows the calculation of a correlation factor for describing the association of polar substances. For the systems n-hexane + diethylether cyclohexane + 1-propanol cyclohexane + 1-butanol benzene + methanol benzene + ethanol benzene + 1-propanol benzene + 1-butanol benzene + 1-hexanol benzene + 1-octanol the experimental values of dielectric constant and the calculated correlation factors are presented. From the concentration dependence of the correlation factors, calculated by use of the KIRKWOOD -FRÖHLICH -equation for mixtures, the existence of widely ramified associations of methanol and the formation of clusters of ethanol, propanol-(1), butanol-(1), hexanol-(1) and octanol-(1) is deduced. In the systems benzene + alcohol in most of the cases some specific interactions between the two components are supposed to exist.     

Poly(lactic acid)/polystyrene bioblends characterized by thermogravimetric analysis,differential scanning calorimetry,and photoacoustic infrared spectroscopy

Bioblends are composites of at least one biodegradable polymer with nonbiodegradable polymer. Successful development of bioblends requires that the biodegradable polymers be compatible with other component polymers. Compatibility can be assessed by evaluating the intermolecular interactions between the component polymers. In this work, the interaction in binary bioblends comprising biodegradable poly(lactic acid) (PLA) and polystyrene (PS) was investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared photoacoustic spectroscopy (FTIR‐PAS). The TGA studies indicated that incorporation of PLA in PS resulted in thermal destabilization of PS. The DSC studies showed that some parameters favored partial miscibility of PS in PLA, while others favored immiscibility, such as the existence of two glass transitions. The FTIR‐PAS spectra revealed the presence of intermolecular n–π interactions between PLA and PS and indicated that the degree of interaction was dependent on the concentrations of the polymers in the bioblends. FTIR‐PAS results computed via differential spectral deconvolution were consistent with, and therefore support, the results of TGA and DSC analyses of PLA/PS bioblends. The degradation kinetics, used to determine the degradation mechanism, revealed a two‐ or three‐step mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Zur unverträglichkeit von polymergemischen. 2. Trübungsmessungen am system polystyrol/polymethylmethacrylat/benzol

The first visual points of turbidity were determined in the ternary system polystyrene/polymethylmethacrylate/benzene. Mathematical equations are given for the dependence of the turbidity points on molecular weight and concentration. It is possible to extrapolate these equations to solid polymers. If the molecular weight of one of the polymers is known, the compatibility in the solid state of the polymers can be calculated. Test measurements on films show, that the method of extrapolation is a valid approximation.     

Orientation of miscible and immiscible polymer blends

Polystyrene (PS) and poly(vinylmethylether) (PVME) were used to study the orientation of miscible and immiscible polymer blends. A miscible blend containing 60 wt% PS was prepared by casting the sample from a benzene solution. The immiscible blend was made by annealing the initially miscible mixture above its lower critical solution temperature for different times and temperatures. Fourier transform infrared spectroscopy and birefringence were used to measure the orientation of PS and PVME, before and after phase separation. Stress-strain curves were also measured for the two types of systems. It was found that the two polymers orient differently and that phase separation induces an increase in the overall orientation of the mixture, in the modulus and in PS orientation. The differences observed between pure PS and PS in the blend were attributed to changes in specific interactions and density of entanglements. The variations with phase separation were attributed to a change in the morphology of the system.     

Interfacial tension in polymer melts. Part II: Effects of temperature and molecular weight on interfacial tension

Interfacial tension is one of the most important parameters that govern the morphology of polymer blends and the quality of adhesion between polymers. However, few data are available on interfacial tension due to experimental difficulties. A pendant drop apparatus was used for the determination of the interfacial tension for the polymer pair polypropylene/polystyrene (PP/PS). The effects of temperature and molecular weight were evaluated. The range of temperatures used was from 178° to 250°C, and the range of molecular weights used was from 1590 to 400,000. The interfacial tension decreased linearly with increasing temperature. With only one exception, higher molecular weight systems showed weaker dependence of interfacial tension on temperature than lower molecular weight systems. Also, polydisperse systems showed a stronger dependency on temperature than the monodisperse systems. The value of the interfacial tension, which increases with molecular weight, appears to level off at molecular weights above the entanglement chain length. For the polymer pair PP/PS, the dependency of the interfacial tension on the number average molecular weight appears to follow the well-known semi-empirical (?2/3) power rule over most of the range of molecular weights. Comparable correlations were obtained with values of the power between ?1/2 and ?1.0.     

Synthesis of isopropenylbenzyl‐terminated macromonomers and preparation of polymer brushes by anionic homopolymerization

Isopropenylbenzyl‐terminated polystyrene (PS) macromonomers were synthesized by anionic addition in a two‐stage process using styrene and 1,4‐diisopropenylbenzene (DIPB) in benzene. The reaction products of polystyryl anions with DIPB provided PS macromonomer possessing less than two isopropenylbenzyl groups at the propagating end under the condition of being in hydrocarbon solvent at 25°C (ceiling temperature) because of the anionic equilibrium nature. Subsequently, anionic homopolymerization of such macromonomers was carried out in tetrahydrofuran (THF) at ?78°C using anionic initiators to prepare the polymer brushes. The conversion of polymer brushes was very low (ca. 5%). Moreover, the degree of polymerization (DP) was less than 50. The low concentration of propagating chain ends seemed to affect the formation of polymer brushes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87:1790–1793,2003     

Preferential adsorption behaviour of several vinyl polymers in poly(ethylene glycol)(1)/THF(2)

Summary The preferential sorption coefficient in the ternary systems vinyl polymers (3)/Poly (ethylene glycol) (1)/THF(2) has been determined in dilute solutions by dialysis equilibrium differential refractometry at 633 nm and 298 K. A series of vinyl polymers of different side groups (Polystyrene, Poly (p-iodostyrene), Poly (n-vinyl carbazole), Poly (vinyl chloride) and Poly (methyl methacrylate)) has been studied.The results indicate that polymer side group play a fundamental role in the solvation behaviours of vinyl polymers. The characteristics of the polymer side group influences the kind and intensity of the polymer-binary solvent interactions and so, the rest of solution properties of these systems.     

The characteristic properties of poly(methyl methacrylate)/polystyrene core‐shell composite polymer latex

In this study, the poly(methyl methacrylate/polystyrene (PMMA/PS) core‐shell composite latex was synthesized by the method of soapless seeded emulsion polymerization. The morphology of the PMMA/PS composite latex was core‐shell structure, with PMMA as the core and PS as the shell. The core‐shell morphology of the composite polymer latex was found to be thermally unstable. Under the effect of thermal annealing, the PS shell region first dispersed into the PMMA core region, and later separated out to the outside of the PMMA core region. This was explained on the basis of lowing interfacial tension between the PMMA and PS phases owing to the interpenetration layer. The interpenetration layer, which was located at the interface of the core and shell region, contained graft copolymer and entangled polymer chains. Both the graft copolymer and entangled polymer chains had the ability to lower the interfacial tension between the PMMA and PS phases. Also, the effect of thermal annealing on the morphology of commercial polymer/composite latex polymer blends was examined. The result showed that the core‐shell composite latex had the ability to enhance the compatibility of the components of polymer blends. The compatibilizing ability of the core‐shell composite latex was better than that of a random copolymer. Moreover, the effect of the amount of core‐shell composite latex on the morphology of the polymer blend was investigated. The polymer blends, which contained composite latex above 50% wt, showed the morphology of a double sea‐island structure. In addition, the composite latex was completely dissolved in solvent to destroy the core‐shell structure and release the entangled polymer chains, and then dried to form the entangled free composite polymer. The entangled free composite polymer had the ability to enhance the compatibility of the components of the polymer blend as usual. The weight ratio 3/7 commercial polymer/entangled free composite polymer blend showed the morphology of the phase inversion structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 312–321, 2003     

Phase distribution and separation in poly(2-acetoxyethyl methacrylate)/polystyrene latex interpenetrating polymer networks

A series of latex interpenetrating polymer networks (LIPNs) were prepared via two-stage soap-free emulsion polymerization of styrene on cross-linked poly(2-acetoxyethyl methacrylate) (PAEMA) seed latexes, using potassium persulfate as initiator. It was found that a compositional gradient was present when PAEMA seeds cross-linked either lightly or highly were used. The polystyrene (PS) phase is localized near the particle center in the former case, while it is segregated near the surface in the latter case. A uniform distribution of PS phase in LIPN was formed, if moderately cross-linked PAEMA seed was used. All the LIPNs appeared to be microphase-separated, and increase of cross-linking degree in seed latexes decreased the PS-rich domain size. The results were explained by the particle growth mechanism that involved the formation of surface-active oligomeric radicals in water phase, adsorption of the radicals onto monomer-swollen particle/water interface, and chain propagation in the interface with subsequent phase migration dominated by the competitive effects of thermodynamics and kinetics.     

Asphaltene/polymer composites: Morphology,compatibility, and rheological properties

In this study, we investigate the use of asphaltene, a natural waste product that is inevitably formed during heavy oil processing, as a filler in polymer composites. The focus of this work is on the compatibility of various asphaltenes, featuring different polarities, with several polymers, including polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), and polycarbonate (PC). The Hansen solubility parameters were plotted to predict the compatibility of polymers with different asphaltenes. Then, polymer composites were prepared by two common techniques: melt mixing and solution mixing. The dispersion state of the asphaltenes in each polymer was investigated by using imaging and rheological techniques. This work showed that the network structure of the asphaltenes and, thus, the final properties of the composites can be controlled by the polarity of asphaltenes, mixing technique, and melt viscosity of the polymer. For instance, more polar asphaltene (Asph P) produced smaller aggregates in PMMA, which has a higher polar solubility parameter than PP or PS. At 2.5 wt.% of asphaltene, Asph P showed 26% and 177% larger asphaltene agglomerates in PP and PS, respectively, than the less polar asphaltene (Asph Al). PS/asphaltene and PMMA/asphaltene composites prepared by the solution mixing method exhibited better dispersion compared to their melt-mixed counterparts. In melt-mixed composites, the dispersion quality of the asphaltene was better for polymers with higher melt viscosity. Thus, a careful choice of polymer, asphaltene, and preparation conditions can be used to tune the properties of asphaltene/polymer composites.     

Organosiliciumverbindungen mit funktionellen gruppen und ihre überführung in makromoleküle

By polymerizing unsaturated oligomers of siloxane derivatives (I) and by copolymerizing them with the usual vinyl monomers a variety of soluble polymers can be obtained which possess different organic structural units and di- or polysiloxane substituents. Hereby the siloxane content can vary greatly and in case of some homopolymers may amount to as much as 50 yo, When using polysiloxanes with two unsaturated end groups instead of monofunctional siloxane compounds analogous products are obtained which are however cross-linked and insoluble. Linear organic polymers with Functional silicon-substituents (such as Cl? Si? , HO ? Si? , H ? Si? , CH₂ ? CH? Si? , CH₂?CH? CH₂? Si? , CH?C? Si, n? C₄H₉O? Si? , ClCH₂? Si? groups) are formed by homo-, and copolymerization of silanes and siloxanes which contain a functional moiety besides the unsaturated group. Macromolecules which carry the functional substituents on the ends of the chains instead of exhibiting them as side groups can be prepared by termination of living polymers with chlorosilanes or by initiation of anionic vinyl polymerization with organometallic starter molecules. High molecular weight polymers with two reactive end groups may also be obtained by cohydrolysis or equilibration reactions of the corresponding chlorosilanes or disiloxanes. By these synthetic routes a great number of organic or silicone polymer molecules with functional groups in side or end positions are available by suitable block, graft, and crosslinking reactions in polymer systems with definite structural units, and tailor made micro structures. To achieve this, polymer molecules of different structure are linked together by suitable reactions of their functional groups or one uses polymer molecules with reactive centers as poly-functional initiators for the polymerization reaction. By addition polymerization of organic diisocyanates with oligomer siloxane or silmethylene diols, silicon-modified polyurethanes are obtained. The reaction of the partners in molar ratio 2/1 leads to low molecular weight polyurethanes (degree of addition polymerization m 2) with two isocyanate end groups, which could be employed in the diisocaynate addition polymerization as easily available silicon-containing diisocyanates. Oligomer siloxanes or silmethylenes with two H? Si-end groups (I), (R and R₁?H) and ω,ω′-divinyl- or ω,ω′-diallylpolysiloxanes (I), (R and R¹ ? vinyl-, allyl-) or several other unsaturated molecules, such as p-divinylbenzene and acetylene undergo addition polymerization to give heat stable polysilcarbanes, in which oligomer siloxane or silmethylene groups are linked via ethylene or n-propylene bridges. If the siloxane or silmethylene groups are replaced by ferrocenyl-groups, polyadducts result which are stable up to 400°C for several hours in presence of oxygen. Polycarbonates and polyesters are the condensation polymers of siloxane-containing diphenols and phosgene or terephthalic acid chloride. Polyimides, which are soluble, fusible and stable above 300°C, are the condensation products of silicon-containing dianhydrides and diamines or of organosilicon derivatives of diamines and pyromellitimide, and several organosilicon compounds are also the condensation polymers of dichloro-Si-compounds and N,N′-bis-(3-dimethylhydro-xisilylpropyl)-pyromellitimide, which is a very easily available disilanol. A comparatively lowering of melting points and glass transition points of organic polymer molecules possessing polysiloxane derivatives (approximately 5 wt.-% onwards) is due to the covalent bonds of polysiloxanes. Moreover, one notices also great improvement in solubility as well as in their hydrophobic character. A great improvement in heat stability can be achieved by introducing more siloxane-content (approximately 15 wt.-% onwards).     

ÜBer die gegenseitige durchdringung von polymerknäueln im θ-zustand

The degree of mutual penetration of random coils close to the ?-point was investigated by evaluation of the maximum conversion of the reaction of a OH-groups containing polymethylmethacrylate (PMMA) with a COCl-groups containing PMMA in a mixture of benzene and n-hexane. We have found, that the degree of coil penetration in ?-solvents has the same value as in good solvents, namely 5 to 20% of the coil volume with a polymer concentration of 10 to 30 wt.-%. Sterical factors are discussed as the reason for the small mutual penetration of the coils. Because of 1-T/? = 0 no energy barrier can be present.     

Effect of decrosslinking and annealing on interpenetrating polymer networks prepared from poly(ethyl acrylate)/polystyrene combinations

Interpenetrating polymer networks, IPN polymers, were prepared from poly(ethyl acrylate), PEA, and polystyrene, PS. Part or all of the crosslinking monomer was acrylic acid anhydride, AAA, which was subsequently hydrolysed and the samples annealed. Modulus-temperature, modulus-time (during annealing) determinations, and transmission electron microscopy were performed on the freshly made samples, after hydrolysis, and after annealing. The studies show that the phase continuity of the PS component is increased relative to the PEA component on annealing, and the separation of the phases becomes more pronounced. A new morphology was observed with the totally decrosslinked, chemically induced blend, with the PEA showing both a continuous and a discontinuous aspect.     

Phase separation and morphology in polymer modified colloids

The morphology of films of sterically stabilised polystyrene particles, PS, with added free poly(vinyl alcohol), PVA, and poly(vinyl pyrrolidone), PVP, was investigated with scanning electron microscopy and correlated to the phase behaviour and interactions. In the case of the PS/PVP system exhibiting depletion phase separation, large polymer domains (ca. 7 μm) were present in the solid state when free polymer concentration exceeded ca. 13%. This concentration was well within the two-phase region of the phase diagram. Similar polymer domains were also observed for the homogeneous system PS/PVA. The surface of the films was sealed at free polymer concentrations of ca. 20% and ca. 40% for PVP/PS and PVA/PS, respectively. The final film morphology reflects non-equilibrium conditions arising from the increase in system viscosity due to particle close packing and continuous phase thickening by the free polymer. In the case of PS/PVP systems, incomplete depletion phase separation and phase demixing and prevention of particle restabilisation gives rise to large free polymer domains in the final film. Bridging flocculation was argued to be responsible for the large polymer domains, some with internal structure, observed with the PVA/PS systems.     

The stability of poly(ether urethane)/polydimethylsiloxane interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) are a special type of polymer blend consisting of two polymer networks synthesized and/or cross-linked independently within each other. One potential approach for the preparation of composite materials from polymers having desirable physical characteristics obtained by modifying their surfaces with physiologically acceptable polymers involves IPN technology. An IPN based on a poly(ether urethane) and polydimethylsiloxane has been synthesized and charaterized using optical microscopy, dynamic mechanical analysis, and scanning electron microscopy. The stability of poly(ether urethane)/polydimethylsiloxane composites were studied in hydroxyl radical aqueous solutions over 30 weeks. The data suggest that these composites have good potential for biomedical applications. © 1995 John Wiley & Sons, Inc.     

A comparative study of semi-2 and full interpenetrating polymer networks based on poly(n-butyl acrylate)/polystyrene

Sequential poly(n-butyl acrylate)/polystyrene (PnBA/PS) semi-2 and full IPN's of various compositions were made by UV photopolymerization. Acrylic acid anhydride and divinylbenzene were used as labile and permanent crosslinkers, respectively, for the rubbery phase and the plastic phase. After IPN formation, network I was selectively decrosslinked. After extracton of polymer I, the remaining PS network II was characterized by swelling measurements and examined by scanning electron microscopy. It was found that crosslinked PnBA affects the formation of the second network more than uncrosslinked PnBA does. A porous phase formed by an aggregate of spherical polystyrene domains was observed. The experimental domain diameter was in good agreement with previous theoretical values. The dynamic mechanical properties of full IPN's, decrosslinked IPN's, and semi-2 IPN's were also studied. A significant level of molecular mixing was found for full IPN's of midrange compositions. The major difference between the full IPN's and the decrosslinked IPN's is that the glass transitions of the respective polymers become more pronounced in the latter case, with a deeper valley between them. With the destruction of the crosslink sites, there is no longer a forced miscibility of the interlocked phases, which are, in fact, thermodynamically incompatible.