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Bis‐carbonylimidazolide (BCI) functionalization enables an efficient synthetic strategy to generate high molecular weight segmented nonisocyanate polyurethanes (NIPUs). Melt phase polymerization of ED‐2003 Jeffamine, 4,4′‐methylenebis(cyclohexylamine), and a BCI monomer that mimics a 1,4‐butanediol chain extender enables polyether NIPUs that contain varying concentrations of hard segments ranging from 40 to 80 wt. %. Dynamic mechanical analysis and differential scanning calorimetry reveal thermal transitions for soft, hard, and mixed phases. Hard segment incorporations between 40 and 60 wt. % display up to three distinct phases pertaining to the poly(ethylene glycol) (PEG) soft segment Tg, melting transition, and hard segment Tg, while higher hard segment concentrations prohibit soft segment crystallization, presumably due to restricted molecular mobility from the hard segment. Atomic force microscopy allows for visualization and size determination of nanophase‐separated regimes, revealing a nanoscale rod‐like assembly of HS. Small‐angle X‐ray scattering confirms nanophase separation within the NIPU, characterizing both nanoscale amorphous domains and varying degrees of crystallinity. These NIPUs, which are synthesized with BCI monomers, display expected phase separation that is comparable to isocyanate‐derived analogues. This work demonstrates nanophase separation in BCI‐derived NIPUs and the feasibility of this nonisocyanate synthetic pathway for the preparation of segmented PU copolymers. [ABSTRACT FROM AUTHOR]

Characterization of the molar mass distribution (MMD) of poly (ether ether ketone) (PEEK) is very troublesome due to the insolubility of PEEK in common solvents. The solubility of PEEK may be substantially improved after its sulfonation. Sulfonated PEEK (SPEEK) was prepared by sulfonation of PEEK with 98% concentrated H2SO4 at room temperature. The presence of sulfonic acid group (‐SO3H) in PEEK matrix was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy. The degree of sulfonation (DS ~ 95%) was determined by proton nuclear magnetic resonance in deuterated dimethyl sulfoxide and by thermal analysis methods. The equivalent molar mass and MMD of sulfonated PEEK was determined at 30°C in three polar solvents (N,N‐dimethylacetamide, N,N‐dimethylformamide N‐methyl‐2‐pyrollidone) in PS/DVB column using calibration with PMMA standards. A salt (LiBr) was added to the solvents for suppression of undesired interactions of analytes with the column packing. Moreover, the sulphonated PEEK was separated with size exclusion chromatography (SEC) coupled to a multi‐angle light scattering (MALS) detector. It was found that the absolute average molar mass of SPEEK from the MALS detection is much closer to the value measured by SEC in N,N‐dimethylacetamide +LiBr than the values determined in N,N‐dimethylformamide and N‐methyl‐2‐pyrollidone. [ABSTRACT FROM AUTHOR]

Systematic studies of the influence of the basic powder characteristics and its sintering conditions on the physical and mechanical properties of samples intended for the implementation of the technology of powder injection molding of products from typical heat-resistant high performance engineering polymers - crystallizing polyetheretherketone (PEEK) and amorphous polyphenylene sulfone (PPSu) - were carried out. Polymers with different MW were synthesized as initial materials and powders with different sizes and bulk density were obtained. The influence of these parameters on the nature of powder sinterability and, as a consequence, on their elastic modulus and tensile strength was shown. Optimum characteristics for bulk density and sintering temperature were established, which provide maximum values of mechanical characteristics of the molded samples. The results of the fundamental research conducted allowed us to produce two typical products for biomedicine - an intervertebral cage (an implant replacing a removed vertebra) and a blood dialyzer part. [Display omitted] • Products made from high-temperature engineering poplymers can be produced using powder casting. • The quality of the products depends on the properties of the powder and the sintering conditions. • The best sintering temperature depends on the MW and the fractional composition of the powder. • The correct mode of sintering allows us to obtain products corresponding by quality to cast samples. • The addition of nanosized aerosil particles improves the technological properties of the powder. [ABSTRACT FROM AUTHOR]

This study reports on the development of a novel polymer processing approach that combines low-temperature (LT) processing and fibre direct compounding (FDC) to reduce the thermal stress on thermosensitive components that occurs during compounding and subsequent injection moulding (IM). Composites based on polyamide 6 (PA6) and cellulose fibres (CeF) were prepared using an LT-FDC process and in parallel with a conventional approach using a twin-screw extruder and IM. The morphological, optical, thermal, and mechanical properties of the prepared samples were investigated using optical microscopy (OM), differential scanning calorimetry (DSC), colorimetry, dynamic mechanical analysis (DMA) and tensile tests. Composites prepared using LT-FDC exhibited worse fibre dispersion but lower fibre degradation. In comparison to neat PA6, the LT-FDC composites had increased tensile modulus (Et) and storage modulus (E′) at 120 °C by up to 32% and 50%, respectively, while the tensile strength (σm) decreased by 20%. [ABSTRACT FROM AUTHOR]

1,1′‐Carbonyldiimidazole (CDI) provides a platform to generate high molecular weight polyurethanes from industrially relevant diols and diamines. CDI, which is described in the literature for its use in amidation and functionalization reactions, enables the production of well‐defined and stable polyurethane precursors, thus eliminating the need for isocyanates. Herein, the functionalization of 1,4‐butanediol with CDI yields an electrophilic biscarbamate, bis‐carbonylimidazolide (BCI), which is suitable for further step‐growth polymerization in the presence of amines. Elevated reaction temperatures enable the solvent‐, catalyst‐, and isocyanate‐free polycondensation reaction between the BCI monomer and various diamines. The thermoplastic polyurethanes produced from this reaction demonstrate high thermal stability, tunable glass transition temperatures based on incorporation of flexible polyether segments, and mechanically ductile thin films. CDI functionalized diols will allow the preparation of diverse polyurethanes without the use of isocyanate‐containing monomers. [ABSTRACT FROM AUTHOR]

Poly(L-Lactide) (PLA), a fully biobased aliphatic polyester, has attracted significant attention in the last decade due to its exceptional set of properties, such as high tensile modulus/strength, biocompatibility, (bio)degradability in various media, easy recyclability and good melt-state processability by the conventional processes of the plastic/textile industry. Blending PLA with other polymers represents one of the most cost-effective and efficient approaches to develop a next-generation of PLA-based materials with superior properties. In particular, intensive research has been carried out on PLA-based blends with engineering polymers such as polycarbonate (PC), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT) and various polyamides (PA). This overview, consequently, aims to gather recent works over the last 10 years on these immiscible PLA-based blends processed by melt extrusion, such as twin screw compounding. Furthermore, for a better scientific understanding of various ultimate properties, processing by internal mixers has also been ventured. A specific emphasis on blend morphologies, compatibilization strategies and final (thermo)mechanical properties (tensile/impact strength, ductility and heat deflection temperature) for potential durable and high-performance applications, such as electronic parts (3C parts, electronic cases) to replace PC/ABS blends, has been made.

The frictional behavior of (PA6 E and PETP) engineering polymers commonly used in the industry were investigated implying 3D surface topography due to Dielectric Barrier Discharge (DBD) source, atmospheric cold plasma surface treatment and compared to the pristine surface results under the same test conditions. The 3D surface topography shows a decrease in the surface roughness after treatment and keeps good topographical stability with the function of time. The friction coefficient of treated samples were lower than the pristine one under "runout" lubrication conditions in line with surface characterization results. [ABSTRACT FROM AUTHOR]

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The article discusses a study which examined the active confinement pressures due to cooling of heated polymeric ties in order to analyze if polymeric materials can be used as a reinforcing material for load-bearing rock columns or pillars. Series of experiments showed that polyamide ties can provide rapid confinement pressure, but slow heating process is suggested to not affect the polymeric structure and bonds.

Abstract: Two methods for the determination of phosphate-based flame retardants (PFRs) and similar organophosphates (OPs) were developed. Two gas chromatographic systems were applied, one equipped with a quadrupole mass spectrometer (GC/MS), the other with a specific phosphorus–nitrogen detector (GC/PND). A procedure of ultrasonic supported extraction and precipitation (USSE) was applied and verified using in-house produced reference materials. Twelve polymer parts of electrical and electronic devices, and eight polymer references were analysed for their PFR contents. The results show that the methods are capable of identifying PFRs in concentration ranges from 3μgL−1 (tricresyl phosphate, TCP) to 12μgL−1 (cresyl diphenyl phosphate, CDP) on GC/PND and from 110μgL−1 (triphenyl phosphine oxide, TPPO) to 3250μgL−1 (tris(ethylhexyl) phosphate, TEHP) on GC/MS in reference solutions. LODs in polymer extracts range from 180μgg−1 (triphenyl phosphate, TPP) to 670μgg−1 (bisphenol-A-bis(diphenyl phosphate), BDP) on GC/PND and from 75μgg−1 (TPPO) to 780μgg−1 (BDP) on GC/MS. The overall procedure time for one sample was less than 45min (GC/MS) and less than 65min (GC/PND). [Copyright &y& Elsevier]

Acrylonitrile butadiene styrene (ABS) was grafted using long chain molecules like oleic acid and dodecylamine. Grafting took place at the butadiene region of ABS. Grafted ABS (g-ABS) polymers were characterized using FTIR and blended with nylon-66 in various proportions. Physical, chemical, mechanical and thermal properties of the blends were analyzed. A physical blending technique was followed between nylon-66 and ABS and all properties were compared with the modified blends. SEM reveals that miscibility characteristics were found to be enhanced, as the modification of ABS makes it more compatible with nylon-66. [ABSTRACT FROM AUTHOR]

Abstract: In this series of two papers, various polymeric materials are investigated as to their potential applicability as absorber materials for solar thermal collectors. The focus of the investigation is to study the aging behavior of these materials under maximum operating conditions (80°C in water up to 16,000h) and stagnation conditions (140°C in air up to 500h) typical for northern climate. The materials supplied or produced as polymer films were first characterized in the unaged state and then for different states of aging by differential scanning calorimetry (DSC), by size exclusion chromatography (SEC) and by mechanical tensile tests. Physical aging phenomena were studied by DSC, SEC analysis provided information on chemical degradation of the materials. In addition, physical and chemical aging were both analyzed via the small and large strain mechanical behavior. While the present Part 1 of this paper series deals with the aging behavior of engineering plastics, including two amorphous polymers (a polyphenylene ether polystyrene blend (PPE+PS) and polycarbonate (PC)) and two semi-crystalline polymers (two types of polyamide 12 (PA12)), the aging behavior of so-called “commodity” plastics (PE and PP) is the subject of Part 2. Comparing the two aging conditions, the amorphous materials (PPE+PS and PC) turned out to be more prone to physical and chemical aging at 140°C in air. In contrast, the semi-crystalline PA12 materials were more strongly affected by exposure to water at 80°C, although to different degrees, depending on the modification. [ABSTRACT FROM AUTHOR]

The developments of the catalytic, clean, and ecological decomposition of engineering polymers offer the possibility for new chemical recycle systems. Herein, we report that an aromatic polycarbosilane was completely decomposed by the treatment of 20 mol% TfOH-Air in crude toluene at room temperature to give biphenyl and silicone in quantitative yield. The decomposition of aromatic polycarbosilanes by trifluoromethanesulfonic acid involves the cleavage of the Si-C (sp²) bond. [ABSTRACT FROM AUTHOR]

In the present work two materials of guiding elements were tested in water hydraulic. During investigations of hardness conducted for stuffing box packings in water hydraulic systems an analysis of proper selection of piston rod guiding elements has also been carried out (ø45f7, Ra = 0.07-0.20 lain, Rm ≤ 2.5 µm). Working piston rod has been used for investigations made of chromium-nickel steel AISI 431 (Cr = 16.7%, Ni = 2.08%). Some of the guiding elements, after proper selection of the material, could be still used, despite damaged seal. The tests have been performed maintaining water pressure on the sealing at a level of p = 8±1 MPa and the average velocity of the piston rod of v ≈ 0.35 m/sec. Water temperature during investigations was regulated within the range of Tmin = 291 K and Tmax = 305 K. Variable value of friction coefficient has been obtained for the guide rings made of PTFE composite with the change in piston rod velocity. Application of guide rings made of UHMWPE has been estimated negatively. [ABSTRACT FROM AUTHOR]

The use of engineering resins has increased dramatically in the last years and now the mechanical and chemical properties of the most recent products render these new materials excellent candidates for ultra high vacuum (UHV) applications. In particular, a relatively inexpensive polymer like PEEK® can become competitive when vacuum seals have to be manufactured. In this paper, a systematic series of tests is described, aimed at comparing the properties of PEEK® and traditional Helicoflex seals. Two different designs for the new PEEK® seals were tested. Their performances were compared not only in cases of metal but also of glass plain surfaces. A complete temperature scan was carried out for both applications (metal and glass surfaces) up to 200°C. At room temperature the vacuum properties of PEEK® seals are comparable to those of the more traditional Helicoflex gaskets. At higher temperatures the only significant drawback of the proposed PEEK® prototypes is a significant He permeation. On the other hand, gaschromatographic-mass spectrometer analysis confirms that the outgassing of this material is compatible with UHV requirements. In the temperature range investigated, one of the tested solutions gives very positive results; given the lower cost and much easier handling of this prototype with respect to Helicoflex technology, the proposed design can be considered with great attention as a possible future replacement. [Copyright &y& Elsevier]

We analyze the behavior of blends containing a longitudinal polymer liquid crystal (PLC), namely PET/0.6PHB, where PET denotes poly(ethylene terephthalate), PHB is p-hydroxybenzoic acid, while 0.6 is the mole fraction of the latter in the copolymer. We consider the totality of results obtained experimentally, theoretically using statistical mechanics, and also by molecular dynamics computer simulations. Our PLC is oriented in magnetic fields that improve its mechanical properties and also can serve for reinforcement of engineering plastics. The resistance to deformation depends on the spatial distribution of the LC-rich islands phase in the LC-poor matrix. [ABSTRACT FROM AUTHOR]

For economical, ecological and even technical reasons for some years there has been a tendency to introduce self-lubricating materials for bearing applications. In this way external lubricants such as oil or grease can be excluded, the design can be simplified and maintenance cost can be reduced. Among the self-lubricating materials the so-called engineering plastics have increasing importance. Unfortunately, data on their friction and wear characteristics are very disparate and often there is a lack of general understanding of the physical phenomena involved.In the present paper some basic types of engineering plastics (PA, oil-filled PA PTFE-filled PETP, POM-H) are experimentally investigated by means of small-scale reciprocating tribotesting. The tribological behaviour is explained in correlation with the chemical and mechanical properties of the materials. The basic failure processes are described for mild wear conditions as well as for overload conditions. [Copyright &y& Elsevier]

Recent advances in vat photopolymerization (VP) additive manufacturing of fully aromatic polyimides employed photoreactive high-molecular-weight precursors dissolved at modest loadings (<20 wt %) in organic solvent. These earlier efforts revealed high isotropic shrinkage, approaching 52% on a linear basis while converting to the desired polyimide. To increase the polyimide precursor concentration and decrease shrinkage during VP processing of high-performance polyimides, photoreactive fully aromatic polyimide and thermoplastic polyetherimide (PEI) supramolecular salt precursors now serve as versatile alternatives. Both pyromellitic dianhydride-4,4'-oxydianiline (PMDA-ODA) and 4,4'-(4,4'-isopropylidene-diphenoxy)diphthalic anhydride- meta phenylene diamine (BPADA- m PD) supramolecular dicarboxylate-diammonium salts, termed polysalts, provided prerequisite rheological performance and photoreactivity for VP. Solutions (50 wt %) of both photoactive polysalts exhibited viscosities more than two orders of magnitude lower than previously reported polyimide precursor solutions for VP. In addition, VP of 50 wt % polysalt solutions yielded high resolution, self-supporting organogel structures. During thermal postprocessing to the desired fully aromatic polyimide and PEI, photocrosslinked polysalt organogels exhibited retention of part shape in concert with linear isotropic shrinkage of only 26%, the lowest reported value using organogel strategies for VP of fully aromatic polyimides. Furthermore, the imidized structures exhibited comparable thermal and mechanical properties to analogous polyimides synthesized using classical methodologies for 2D films. The combination of facile synthesis and increased precursor concentrations designates polysalt polyimide precursors as a versatile platform for additive manufacturing of well-defined 3D polyimide structures.

The design of linear high performance polyetherimides (PEIs) comprising 3,3′- and 4,4′-bisphenol-A dianhydride (bis-DA) and m -phenylene diamine (m PD) provided an opportunity to elucidate the influence of dianhydride regiochemistry on thermomechanical and rheological properties. This unique pair of regioisomers allowed the tuning of the thermal and rheological properties for high glass transition temperature polyimides for emerging engineering applications. Step-growth polycondensation enabled the production of high molecular weight PEIs for subsequent thermal and mechanical analysis. Monofunctional phthalic anhydride as an endcapper and monomeric stoichiometric imbalances enabled predictable number-average molecular weights ranging from 3,600 to 35,400 g mol−1, as confirmed with size exclusion chromatography coupled with light scattering detection for absolute molecular weight determination. The selection of the dianhydride regioisomer influenced the weight loss profile as a function of temperature, entanglement molecular weight (M e), glass transition temperature (T g), tensile strain-at-break, zero-shear melt viscosity, average hole-size free volume (V h), and the plateau modulus prior to viscous flow during dynamic mechanical analysis. The 3,3′- PEI composition interestingly exhibited a ~20 °C higher glass transition temperature than the corresponding 4,4′- PEI analog. Moreover, melt rheological analysis revealed a two-fold increase in M e for 3,3′- PEI, which pointed to the origin of the differences in mechanical and rheological properties as a function of PEI backbone geometry. Image 1 • Stoichiometric offsets enabled molecular weight control in step-growth polymers. • Backbone regiochemistry dictates the thermal and rheological properties of PEIs. • Entanglement molecular weight differences impact the thermomechanical properties. [ABSTRACT FROM AUTHOR]

The surfaces of two engineering polymers including polyamide 66 (PA66) and polytetrafluoroethylene (PTFE) were treated by diffuse coplanar surface barrier discharges in atmospheric air. We found that plasma treatment improved the adhesion of PA66 for either polymer/polymer or polymer/steel joints, however, it was selective for the investigated adhesive agents. For PTFE the adhesion was unaltered for plasma treatment regardless the type of used adhesive. Tribological properties were slightly improved for PA66, too. Both the friction coefficient and wear decreased. Significant changes, again, could not be detected for PTFE. The occurred variation in the adhesion and tribology was discussed on the basis of the occurred changes in surface chemistry, wettability and topography of the polymer surface. [ABSTRACT FROM AUTHOR]

A study is presented on cold plasma treatment of the surfaces of two engineering polymers, polyamide 6 (PA6) and polyoxymethylene (POM-C), by diffuse coplanar surface barrier discharges under atmospheric air conditions. We found that plasma treatment improved the adhesion of both polymers for either polymer/polymer or polymer/steel joints. However, the improved adhesion was selective for the investigated adhesive agents that were dissimilar for the two studied polymers. In addition, improvement was significantly higher for PA6 as compared to POM-C. The observed variation of the adhesion was discussed in terms of the changes in surface chemistry, wettability and topography of the polymer surface. [ABSTRACT FROM AUTHOR]

High-performance, all-aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4'-oxydianiline (PMDA-ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all-aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy-intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA-ODA using mask-projection stereolithography, and the preparation of high-resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo-crosslinkable acrylate groups enables light-induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA-ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large-area mask-projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high-performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)