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Bead foams made from standard polymers such as expanded polystyrene (EPS) or expanded polypropylene (EPP) are widely used in everyday products. In order to expand the application window of bead foams, the industry, such as the automotive industry among others, is striving for higher‐performance materials to create a lightweight material for high‐temperature applications. New bead foams such as expanded polycarbonate (EPC) are emerging to offer a wider range of solutions, with thermo‐mechanical properties constantly improving. EPC has excellent mechanical properties, which has been shown in our previous work. To fully understand the capabilities of a material for high‐temperature applications, it is important to know what happens when it is exposed to conditions, that lead to aging. Morphological studies, as well as mechanical characterizations help to determine the properties of EPC compared to EPP. Since thermo‐oxidative aging of thermoplastic foams is almost unexplored, especially in the field of bead foams, this research represents an important contribution to the understanding of material behavior and development. Time‐consuming aging tests were able to confirm that EPC is not only a very thermally stable material, but also able to provide reasonable mechanical performance after aging, compared to EPP.

The dynamic fatigue behavior of the poly(ether-b-amide) (PEBA) elastomers was characterized by a combination of step increase load test (SILT), step increase strain test (SIST), and single load dynamic creep (SLDC). PEBA had crystalline hard segments of polyamide 12 (PA12) and soft segments of poly(tetramethylene oxide) (PTMO). The crystalline morphologies before and after the tests were studied by ex situ wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). Fast stress relaxation can be seen under the applied strain well below than the elongation at break. Remarkable dynamic creep can be observed under the applied load triggering yielding of the specimen, which is substantially less than the ultimate tensile strength. Although the presence of high content of amorphous PTMO renders high entropic elasticity, the disintegration of the crystalline hard domains of PA12 is expected to determine the relaxation rate, creep rate, and modulus, as strain-induced crystallization in soft domains did not occur and no trace was found by WAXD. SAXS patterns showed that the orientation of the PA12 lamellae at lower stresses or strains can largely be restored. However, the fractured and highly aligned PA12 lamellae resulted in classic four-point or two-lobe SAXS patterns, which implied the underlying microstructural changes after the cyclic dynamic tests.

Nowadays, numerous techniques are used to quantify the resistance of cellular polymers against a thermal load. These techniques differ in significance and reproducibility and are all dependent on foam density, structure (i.e., cell size and -distribution) and sample geometry. Very different behaviors are expected for extrusion- and bead foams, as well as for amorphous and semi-crystalline polymers. Moreover, established tests use temperature ramps which would lead to temperature gradients within the sample and thus to faulty results. In this study, we developed a new approach from an engineering perspective to minimize these influences. In this approach, the resistance against the thermal load is derived from a steady creep test with defined temperature steps under a mechanical load, which is specifically set for each foam sample depending on its static compression behavior at room temperature. The two-stage test therefore combines (i) a standard quasi-static compression test at room temperature and (ii) a creep test with stepwise increased thermal loading. For each foam type, a rather low mechanical load (stress) is determined from the quasi-static compression test at room temperature; low enough to remain below the collapse strength and avoid irreversible deformation (i.e., buckling and/or breaking of the cell walls). This load is then applied in a creep test where the temperature is increased in defined steps from room temperature to a temperature close to Tgor Tm. The stepwise increase and holding of the temperature for a defined time enables a homogeneous temperature in the test specimen. The approach was applied to (i) polystyrene extrusion and bead foams (i.e., XPS and EPS), which have different foam structure, (ii) amorphous and semi-crystalline bead foams of polystyrene (EPS) and polypropylene (EPP), (iii) bead foams with different densities (30, 60, 120, and 210 kg/m3) and (iv) to a new type of bead foam made of the engineering polymer polybutylene terephthalate (E-PBT). The termination criterion for the test is defined as the temperature at which a relative compression of 10% is reached in the creep test with temperature steps. We suggest calling it the heat stability temperature THS. For the studied foams, the procedure delivers characteristic THSvalues that allow a good comparison between different polymer matrices and densities. The heat stability temperature THSof amorphous PS foams (i.e., XPS and EPS) was determined to be 98 °C, which is close to the glass transition temperature Tg. Using the same approach, values of 99–107 °C were determined for EPP and 186 °C for the semi-crystalline bead foam E-PBT.

Upcoming efficient air-borne wind energy concepts and communication technologies applying lighter-than-air platforms require high-performance barrier coatings, which concomitantly and nonselectively block permeation not only of helium but also of ozone and water vapor. Similarly, with the emergence of green hydrogen economy, lightweight barrier materials for storage and transport of this highly diffusive gas are very much sought-after, particularly in aviation technology. Here the fabrication of ultraperformance nanocomposite barrier liners by spray coating lamellar liquid crystalline dispersions of high aspect ratio (∼20 000) silicate nanosheets mixed with poly(vinyl alcohol) on a PET substrate foil is presented. Lightweight nanocomposite liners with 50 wt % filler content are obtained showing helium and hydrogen permeabilities as low as 0.8 and 0.6 cm3μm m–2day–1atm–1, respectively. This exhibits an improvement up to a factor of 4 × 103as compared to high-barrier polymers such as ethylene vinyl alcohol copolymers. Furthermore, ozone resistance, illustrated by oxygen permeability measurements at elevated relative humidity (75% r.h.), and water vapor resistance are demonstrated. Moreover, the technically benign processing by spray coating will render this barrier technology easily transferable to real lighter-than-air technologies or irregular- and concave-shaped hydrogen tanks.

A highly efficient flame-retardant hybrid foam material combining expandable polystyrene foam beads and a waterborne resin equipped with inorganic flame retardants is described. The resin and the inorganic fillers were varied, and the different compositions were investigated in small burner and cone calorimeter tests. The burning time during the small burner test decreases from >60 s for neat expandable polystyrene to 0 s for optimized hybrid specimens. The peak of the heat release rate decreases from 661.0 kW/m2for neat expandable polystyrene to 121.36 kW/m2for a hybrid composition of 1:1:1 (expandable polystyrene:aluminum hydroxide:phenol formaldehyde resin). The hybrid materials containing inorganic flame retardants are burning slower and release heat and smoke more constantly at significantly lower rates. Furthermore, a continuous network of the cured thermoset is shown, which leads to embedded expandable polystyrene beads. The flame-retardant thermoset protects the expandable polystyrene from fire and leads to a material with high dimensional stability and efficient flame retardancy.

In this study, the quality of pre-consolidation of a PA6 based glass/carbon hybrid and a glass mono-material UD-tape laminate has been analyzed and the influence of the pre-consolidation step on flexural properties of end-consolidated laminates was determined. For this reason, three different pre-consolidation qualities were mechanically and optically analyzed. The investigations show that the quality of pre-consolidation is not critical for mono-material lay-ups considered in this work. However, the pre-consolidation step has a significant effect on the flexural properties of the hybrid-material laminate presented in this work. The flexural modulus is increased by more than 25 % and the flexural strength up to 9 % due to better welding of the distinct layers. Additionally, the influence of carbon fiber share on the flexural modulus of the UD hybrid-material was examined. It could be recognized that the flexural modulus can be increased up to 171 % by the exchange of glass with carbon fiber layers with a sandwich stacking compared to glass mono-material with constant thickness.

In the present study, a low viscous (complex viscosity between 200 to 500 mPas at 60 °C), flame retardant epoxy resin formulation is prepared and transferred to the carbon fiber reinforced plastic (CFRP) laminate using resin transfer molding (RTM) method. For the laminate production, a 12k carbon fiber fabric with an areal weight of 400 g/m2 is used to achieve a fiber volume content of approximately 60 vol % carbon fibers. Subsequently the unmodified laminate is produced, varying carbon fiber volume content to study its effect on flame retardant properties. As additives, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) modified epoxy resin and nanosilica particles delivered in an epoxy novolac masterbatch are added to the neat novolac resin system. The mixture is cured with isophorone diamine (IPDA) and polyetheramine hardener blend, resulting in a glass transition temperature of 104 °C for the unmodified laminate. Flame retardant properties of the materials are tested using cone calorimeter and thermal gravimetrical analysis. In addition, the mechanical behavior of the systems is evaluated via three-point bending method in static and dynamical loadings. In order to get deeper information on the resulting flame retardant mechanisms of the additives, the residual cone calorimeter char is analyzed with scanning electron microscopy, indicating the different flame retardant mechanisms of phosphorous and silica as well as the combination of both additives.

In this work, the development of a bead foam from the engineering polymer polybutylene terephthalate (PBT) in a continuous process is described. The polymer was chemically modified by means of multifunctional epoxy chain extender (CE) to improve the rheological properties, the foaming behavior, and the fusion of the beads. Shear experiments indicated the formation of branched structures as a result of the chemical modification. Viscosity and melt strength were increased due to the chain extender. Also, strain hardening was observed for PBT modified with CE. It was shown that modified PBT has enhanced foaming behavior; namely, a higher expansion and more homogeneous and finer cell morphology were achieved. For the first time, expanded polybutylene terephthalate bead foams (E-PBT) were produced and welded in a steam chest molding process. The parts from steam chest molded beads showed a density down to 170 kg/m3. An optimum concentration of chain extender in terms of expansion and welding behavior was identified as 1 wt %.

Three-dimensional molded interconnect devices (3D-MID) are commercially produced by the laser direct structuring (LDS)-method with a market share of over 50%. The process chain of this method starts with injection molding. The polymer of this part is functionalized with LDS-additives which allow the part to be laser structured subsequently. This technique is less suitable for prototypes and small-scale productions of 3D-MIDs because of its properties. Contrary to the injection molding process, the additive manufacturing (AM), such as powder bed based manufacturing processes, e.g. selective laser sintering (SLS), is a constantly emerging processing technology for the fabrication of prototypes and small-scale productions. It enables the tool-free manufacturing of highly complex parts. Unmodified polyamide 12 (PA 12), e.g. PA2200 (supplier: EOS GmbH) is most commonly used for the SLS of polymer parts. The LPKF Laser & Electronics AG in Garbsen, Germany, transferred the LDS-method to SLS-process. A standard SLS-polymer part is coated with a special paint, that contains the necessary LDS-additives. Once coated and dried, these parts can be laser direct structured similar to standard 3D-MIDs. In this study, the authors use copper particles in order to functionalize a standard polyamide 12 powder for laser activation and selective metallization. The study shows, that the addition of copper particles enables the laser direct structuring of polyamide 12. SLS-demonstrators were successfully laser activated and selectively metallized. Furthermore, the copper particles enhance the mechanical properties as well as the heat conductivity of polyamide 12.

Several hundred grams of Janus nanoparticles (d≈ 40 nm) were synthesized from triblock terpolymers as compatibilizers for blending of technologically relevant polymers, PPE and SAN, on industry-scale extruders. The Janus nanoparticles (JPs) demonstrate superior compatibilization capabilities compared to the corresponding triblock terpolymer, attributed to the combined intrinsic properties, amphiphilicity and the Pickering effect. Straightforward mixing and extrusion protocols yield multiscale blend morphologies with “raspberry-like” structures of JPs-covered PPE phases in a SAN matrix. The JPs densely pack at the blend interface providing the necessary steric repulsion to suppress droplet coagulation during processing. We determine the efficiency of JP-compatibilization by droplet size evaluation and find the smallest average droplet size of d≈ 300 nm at 10 wt % of added compatibilizer, whereas at 2 wt %, use of JPs is most economic with reasonable small droplets and narrow dispersity. In case of excess JPs, rheological properties of the system is changed by a droplet network formation. The large-scale synthesis of JPs, the low required weight fractions and their exceptional stability against extensive shear and temperature profiles during industrial extrusion process make JP promising next generation compatibilizers.

High density polyethylene (HDPE) – coffee dregs (COFD) composites were studied over a range of seven different temperatures, under isothermal crystallization conditions, using differential scanning calorimetric (DSC) analysis. The aim was to observe the influence of filler content in the crystallization kinetics of HDPE. Seven blends were prepared, the polymer-filler ratio ranging from 100-0 to 40-60%. The results were evaluated using the Johnson-Mehl-Avrami-Kolmogorov equation. The equilibrium melting temperature was determined by applying the Hoffman-Weeks method. The materials were also evaluated through scanning electron microscopy, differential scanning calorimetry and thermogravimetry/derivative thermogravimetry.

The pyrolysis and fire behavior of halogen‐free flame‐retarded DGEBA/DMC, RTM6 and their corresponding 60 vol.‐% carbon fibers (CF) composites were investigated. A novel phosphorous compound (DOPI) was used. Its action is dependent on the epoxy matrix. DGEBA/DMC and DOPI decompose independently of each other. Only flame inhibition occurs in the gas phase. RTM6 shows flame inhibition and a condensed phase interaction increasing charring. Both mechanisms decrease with increasing irradiance, whereas in RTM6‐CF charring is suppressed at low ones. RTM6 + DOPI shows a higher LOI (34.2%) than DGEBA/DMC + DOPI and a V‐0 classification in UL 94. Adding CF only enhances the LOI, DOPI + CF leads to a superposition in LOI for DGEBA/DMC‐CF + DOPI (31.8%, V‐0) and a synergism for RTM6‐CF + DOPI (47.7%, V‐0).

An electret is a dielectric material exhibiting a quasi‐permanent electric charge. The aim of this work is to give access to PC electret materials with a distinctly improved electret performance. In this context, the charge storage capabilities of corona charged films of several PC grades were investigated by isothermal potential decay measurements at 90 °C. The most promising PC grade was further improved by a new class of bisimide additives. The best additive at the most efficient concentration in combination with a physical aging step yielded excellent PC electrets maintaining almost their complete applied charge even at 90 °C.

We reveal that a beam of low‐energy electrons (18 eV) can directly trigger long‐range molecular ordering of an amorphous, semi‐flexible oligomer in a few minutes without the prerequisite of pre‐orientation. A strong endothermic transition was detected with a micro‐thermal analyzer on the areas that had been exposed to the electron irradiation while the areas that were shielded from the irradiation by a protective mask remained amorphous as usual. This result suggests that long‐range molecular ordering only develops in the area of the oligomer film under electron irradiation. This is the first‐time effort to use electron irradiation to control the long‐range ordering of an amorphous organic thin film above the glass transition temperature.

This work introduces a novel facile method to produce shear-stiff, mica-like nanoplatelets by efficient exfoliation. The essence of this procedure is the nonreversible alteration of the interlamellar reactivity of a synthetic fluorohectorite by simple cation exchange. The possibility of switching from highly hydrated to collapsed interlayers permits a highly efficient exfoliation in the swollen state while providing shear-stiffness in the collapsed state. This method restricts cation exchange in the mica-like nanoplatelets to the outer surfaces, which represents a significant advantage for use in nanocomposites as compared to conventional organoclays which contain up to 40%/wt of organocations. It is expected that this new type of rigid, shear-stiff, clay-based nanoplatelets will be superior for reinforcement when used in composite materials like polymer layered silicate nanocomposites or artificial nacre.

In this contribution, we discuss wrinkling as a process resulting in welldefined periodic micronsized structures, as known from the interface of several plant cells. We show possible pathways to transfer this principle to artificial materials such as epoxy resins or polymers. While topographical structuring of surfaces by wrinkling is meanwhile well established for elastomers like poly dimethyl siloxane, so far the step towards other classes of materials has not been taken. This puts several limitations to potential applications of artificial wrinkled structures, as elastomers show poor dimensional stability, low optical quality, and tend to swell in organic solvents. As well, artificial structures formed by wrinkling are not tensionfree on the microscopic level, which makes them metastable. Residual mechanical tensions can affect dimensional stability on long timescales. We introduce two processes, micro thermoforming and molding, as means to overcome these restrictions and to pattern nonelastomeric materials by using wrinkled elastomers as templates. The two approaches allow the formation of negative and positive replicas and allow the transfer of submicron features with high fidelity.

10Ethyl9oxa10phosphaphenanthrene10oxide 1 can be nitrated using acetic anhydride and fuming nitric acid. The nitro group is reduced using palladium on charcoal and hydrogen. These reaction conditions are used for the synthesis of an analogous DOPObased diaminic hardener 7. An evaluation of the curing behavior, mechanical properties and flammability of a neat resin made of DGEBA and 7DGEBA  7 and of a carbon fiberreinforced resin made of DGEBA, 4,4′diaminodiphenylsulfon DDS and 7DGEBA  DDS  7 shows the potential of this hardener to lead to flameretardant systems while keeping relevant properties on a high level; especially when compared to a similar system DGEBA  DDS  1.

The foaming behaviour of polymer blends was systematically investigated using carbon dioxide as a blowing agent. Two batch-processing techniques were used to prepare specimens of different size. Various binary mixtures over a wide compositional range were selected as reference materials, in particular including immiscible (poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) (PPE/SAN) blends. Moreover, the influence of a compatibilization with block copolymers was investigated for PPE/SAN blends. The resulting foam morphology was characterised by evaluating the density, the cell size distribution, the cell wall morphology and the compression behaviour. Besides the commonly accepted key criteria for foaming neat polymers, our study identified significant factors determining the foamability of blends such as the blend morphology, the rheological and the thermal properties. Interestingly, the compatibilization of these PPE/SAN blends by block copolymers was identified as a technique to establish micro- and submicrocellular foam morphologies with nanostructured cell walls. In view of these results, new pathways for the tailoring of cellular materials are derived.

The aim of this work was to establish and better understand the structure-property relationship of fluorinated aromatic poly(ether imide)s (PEI) with respect to their electret performance. Therefore two series of PEIs with increasing fluorine content were synthesized. All PEIs are amorphous materials with glass transition temperatures above 220 °C. Thin films with thicknesses around 100 µm were compression molded and corona charged, and isothermal surface potential decay was investigated at 90 °C as an accelerated test for the electret performance. In comparison to the corresponding non‐fluorinated PEI, an improvement of up to thirty‐fold was achieved by the incorporation of trifluoromethyl moieties. Out of the investigated fluorinated PEIs, the polymer with the best charge storage performance maintained 87% of the initial surface potential charge after annealing at 90 °C for 24 h. It was also found that, within the investigated series, the highest fluorine content does not necessarily result in the best charge‐storage properties.

In this comparative study, the charge storage performance of commercial high-temperature polymer films was evaluated and correlated with their chemical structure. Isothermal surface potential decay measurements after annealing periods at 90 °C revealed that amorphous polyetherimide PEI films showed the best charge storage behavior. Polyimide films showed reduced charge storage performance, whereas sulfurcontaining polymer films are not suitable as electrets due to their fast charge decay. Additionally, the effect of water content in PEI films in the range of 0.02–0.79 wt. was studied. Increasing amounts of water decreased the charge storage properties proportionally, but only by a relatively smaller amount: the highest investigated water content of 0.79 wt. reduced the charge by only 30.

SBS nanocomposites based on a SBS triblock copolymer containing different weight fractions of a commercial Cloisite 20A organoclay were prepared by melt-processing. Extensive electron microscopy as well as WAXS and static tensile and tensile creep tests were used to evaluate the resulting morphological and mechanical properties of the nanocomposites. The nanocomposite morphology is characterized by a combination of intercalated and partly exfoliated clay platelets with occasional clay aggregates present at higher clay contents; nanocomposite features that are reflected by the results of both the static tensile as well as the tensile creep tests at room temperature. For this particular thermoplastic elastomer nanocomposite system, well dispersed nanoclays lead to an enhanced stiffness and ductility; effects that induce promising improvements in nanocomposite creep performance.

A comparative study on the influence of chemical structure and solubility of a series of low-molecular-weight 1,4-phenylene−bisamides in isotactic polypropylene (i-PP) was conducted to explore their performance as nucleating agents and electret additives. The series consists of three isomers of dicyclohexyl-substituted 1,4-phenylene−bisamide and three asymmetrically substituted cyclohexyl/n-alkyl-1,4-phenylene−bisamides with different chain lengths. The symmetry of the molecules, the type of substitution and the length of the alkyl chain influence the solubility in the i-PP melt, the nucleation efficiency, the ratio of the - to -crystal modification and the charge storage properties. The best -nucleating efficiency was observed for the symmetrically substituted compounds, whereas the nucleation efficiency was substantially reduced in the presence of n-alkyl-substituents. The charge storage behavior of i-PP was improved only for the three dicyclohexyl-substituted 1,4-phenylene bisamides at concentrations of 100 ppm and even below. For example, a film comprising 10 ppm additive displayed charge retention of 90% after an accelerated aging (annealing for 24 h at 90 °C).

Summary: The decomposition of novel phosphorus-containing poly(oxyphenylene‐sulfonyl‐phenylene‐oxy‐diphenyl phenylene phosphine oxide) (PSU_I), 2,5‐dihydroxy‐1‐biphenylene‐phosphine oxide based polysulfone (PSU_II), poly(sulfonyl‐diphenylphenylene phosphonate) (PSU_P) and bisphenol A‐based polysulfone (PSU) is studied. The influence of the chemical structure, charring and phosphorus release is discussed based on the mass loss, kinetics and products. The pyrolysis and fire behaviour of blends with epoxy resin (EP) are studied. For EP‐PSU_II, phosphorus initiates water elimination and changes the decomposition pathway of EP. The fire behaviour of EP‐PSU shows some improvements, whereas the heat release rate is crucially reduced for EP‐PSU_II due to simultaneous char formation and flame inhibition.Decomposition model of PSU_II.

This paper will discuss the biocompatibility and dynamic fatigue properties of polystyrene-b-polyisobutylene-b-polystyrene thermoplastic elastomer with 30 wt % polystyrene (SIBS30), an emerging FDA-approved biomaterial. SIBS30 is a very soft, transparent biomaterial resembling silicone rubber, with superior mechanical properties. Using the hysteresis method adopted for soft biomaterials, the dynamic fatigue properties of SIBS30 were found to be between those of polyurethane and silicone rubber, with fatigue life twice as long as that of silicone. Under single load testing (SLT, 1.25 MPa), SIBS30 displayed less than half the dynamic creep compared to silicone, both in air and in vitro (37 °C, simulated body fluid). Hemolysis and 30- and 180-day implantation studies revealed excellent biocompatibility of the new biomaterial. The results presented in this paper indicate that, in comparison with silicone rubber, SIBS30 has similar biocompatibility and superior dynamic fatigue properties.

A study on the influence of the crystal modification (α and β) of isotactic polypropylene (i‐PP) films on the resulting electret properties is presented. Two commercial nucleating agents, sodium 2,2′‐methylene‐bis(4,6‐di‐tert‐butylphenyl)‐phosphate (NA11) and N,N′‐dicyclo‐hexyl‐2,6‐naphthalene‐dicarbox‐amide (NU100), were employed in this investigation. Isothermal charge decay was measured at 90°C. In hot pressed isotropic polypropylene films, no significant differences in the charge storage properties were observed for α‐ and β‐nucleated specimens. In addition, the article presents the influence of the nucleating agents at different concentrations on the PP‐film morphology of biaxially stretched films with respect to electret features. It was possible to prepare elongated cavities with the virtually insoluble NA11 additive during stretching, even at concentrations below 0.3 wt %. These films displayed slightly improved electret properties in comparison to stretched neat PP films due to generated cavities acting as barriers for the drift of charges. Various draw ratios were also studied for i‐PP films with 0.15 wt % NA11. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 650–658, 2006

Summary: The synthesis of novel phosphorous-containing aromatic polyethers P-PEEK and P-PSU, based on poly(ether ether ketone)s (PEEK) and poly(ether sulfone)s (PSU) was carried out successfully by using phosphorous-containing aromatic diols instead of bisphenol A in the usual synthesis procedure. The molecular weights of the P-PEEKs and P-PSUs obtained reflect both the influence of the different halogen components used and the lower thermal stabilities of the phosphorous-containing diols compared to bisphenol A. However, polymers with sufficient molecular weights could be obtained, having interestingly high Tgs, high thermal stabilities as well as modified flame retardance properties depending on the diol type incorporated.Comparison of the molecular weights of the synthesized P-polyethers.

The goal of the work presented here was to synthesize multiblock copolymers based on transesterification polycondensation of end group functionalized PEEK with PSU oligomers in the melt. In the synthesis of PEEK oligomers by nucleophilic aromatic substitution cyclization occured observed by decreasing amount of end groups. The phase behavior of the multiblock copolymers was examined by differential scanning calorimetry and transmission electron microscopy and a phase diagram was constructed. The experimental results were compared with spinodals calculated by Mean Field Modelling. It could be shown that the very similar structure of the blocks and the insufficient high block molecular weights were responsible for the observed non-phase separated morphologies. The thermal properties of the multiblock copolymers can be controlled by the segment length of the PSU oligomers. The glass transition temperature is increased provided that the segment length of PSU oligomers is lower than 8000 g mol−1

Rheotens melt elongational experiments were performed to evaluate polyethersulfone with regard to its foamability. The effect of polymer molecular weight was correlated with the resulting foam cell morphology achieved under identical processing conditions in a batch process. It appears, that the melt strength of the polyethersulfone governs the average cell size, cell size distribution, as well as cell wall rupture during expansion and the corresponding compressive properties of the foam. These effects were further verified by a variation of the blowing agent content for polyethersulfone with a given molecular weight.

This article features macromolecular engineering via carbocationic polymerization, the focus of research of the recently established Macromolecular Engineering Research Centre (MERC) at the University of Western Ontario. The fundamental philosophy of MERC is interdisciplinary research with a strong industrial orientation, while emphasizing the quest for fundamental understanding of polymerization processes and polymer structure-property relationships. First, a brief overview of living polymerizations in general, and living carbocationic polymerizations in particular will be given. This latter technique is of interest because some monomers (e. g., isobutylene) can be polymerized by cationic techniques only, to yield polymers with unique properties (e. g., polyisobutylene with superior chemical and oxidative stability, low permeability and high damping). This will be followed by an overview of our research strategy and a summary of our latest results. These include the development of a fiber-optic mid-FTIR method for the real-time monitoring of low temperature polymerization processes, the discovery that selected epoxides initiate effectively the living carbocationic polymerization of isobutylene, fundamental studies into the mechanism and kinetics of living carbocationic polymerization, and the design and synthesis of various polymer architectures (e. g., branched homo- and block copolymers) with improved properties and nanostructured phase morphologies.

An imide dicarboxylic acid was prepared from 1,6-diaminohexane and trimellitic anhydride and esterified with ethanol. This imide monomer was polycondensed with three different poly(tetramethylene oxide) diols (PTMO-650, PTMO-1000 and PTMO-2000) and with an excess of 1,4-dihydroxybutane. When PTMO-1000 was used, and even more when PTMO-2000 was used, a partial macrophase separation occurred at the end of the polycondensation process. The resulting poly(ether-ester-imide)s (PEEIs) were characterized by IR and 1H NMR spectroscopy, by viscosity and DSC measurements. Compared to thermoplastic elastomers based on poly(butylene terephthalate) these PEEIs crystallize slowly. Selected PEEIs were also characterized by dynamic melt rheology, by dynamic mechanical thermoanalysis, by stress–strain and by hysteresis measurements.

Starting from 1,4-diaminobutane and trimellitic anhydride a bisimide dicarboxylic acid was prepared which was transformed into its diethyl ester. This imide monomer was polycondensed with mixtures of 1,4-dihydroxybutane and poly(tetramethylene oxide) (PTMO) diols having number average molecular weights (Mns) of 650, 1000 or 2000Da. For each PTMO diol, the weight fraction of the hard segments was varied from 30 over 40 and 50–60%. For the PTMO diols 1000 and 2000, macrophase separation was observed during polycondensation. This problem was solved in the case of PTMO-1000 by a PTMO diol of greater polydispersity. The chemical structure of the poly(ether-ester-imide)s, PEEIs, was characterized by IR and 1H NMR spectroscopy. The phase transitions were identified by DSC and DMTA measurements, which revealed that all members of this series were slowly crystallizing materials. The mechanical properties were determined by stress–strain and hysteresis measurements. Macrophase separation during the polycondensation was reflected in poorer mechanical properties.

With regard to upcoming regulations of common chemical blowing agents for epoxy foams, carbamates provide suitable alternatives. They act as blowing agents releasing CO2and cure epoxy resins after decomposition and amine release. Thus, no undesired byproducts occur. In this study, a detailed analysis of the chemical structures, the decomposition, and the curing behavior of the carbamates received from N-aminoethylpiperazine (B-AEP), 4-methylcyclohexane-1,3-diamine (B-DMC), and isophorone diamine (B-IPDA) was attempted. The carbamates were finally used for foaming of diglycidylether of bisphenol-A (DGEBA)-based epoxy resins at different temperatures. By this, the performance of the carbamates in a foaming experiment could be qualitatively compared. The results show that all carbamates are suitable for foaming at specifically adapted temperatures. While B-DMC is able to foam properly only at 80 °C, B-IPDA requires 100–120 °C, and B-AEP is best used for foaming in the range between 120 and 140 °C.

Back Cover:The schematic image presents an oligomer that contains an active dipole group and can be aligned by a low‐energy electron beam. This novel finding offers a facile method to control molecular ordering and allows versatile patterning of ordered and disordered regions as imprinted by a mask. Further details can be found in the article by Y. T. R. Lau, L. T. Weng, K. M. Ng, M. Kempf, V. Altstädt, J. M. Schultz, C.‐M. Chan*on page 634.

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