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1

The influence of the ageing-fatigue degradation on the mechanical properties of glass-reinforced composites

Szymiczek M., Rojek M., Wróbel G.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 1

113--119

EN

Drawing up diagnostic relations between thermal characteristics determined in thermal imaging examinations and mechanical properties, allowing for forecasting the state of material during the use, was a purpose of the work. Research was performed on polyester – glass composites which were subjected to the ageing-fatigue degradation process in a device created specifically for that purpose. It was indicated how to assess the degree of the decline, taking into account the fall in material strength properties. The basis of a method was measurement of changes in temperature in activated thermal processes. Relations between changes of the speed of heating and cooling were related to the bending strength and the modulus of elasticity. Diagnoses were backed up with microscopic examinations.

2

Mechanical and thermal properties of tungsten carbide – graphite nanoparticles nanocomposites

Kornaus K., Gubernat A., Zientara D., Rutkowski P., Stobierski L.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 2

84--88

EN

Previous studies concerning pure tungsten carbide polycrystalline materials revealed that nanolayers of graphite located between WC grains improve its thermal properties. What is more, pressure-induced orientation of graphene nano platelets (GNP) in hot pressed silicon nitride-graphene composites results in anisotropy of thermal conductivity. Aim of this study was to investigate if addition of GNP to WC will improve its thermal properties. For this purpose, tungsten carbide with 0.5–6 wt.% of GNP(12)-additive underwent hot pressing. The microstructure observations performed by SEM microscopy. The anisotropy was determined via ultrasonic measurements. The following mechanical properties were evaluated: Vickers hardness, bending strength, fracture toughness KIc. The influence of GNP(12) addition on oxidation resistance and thermal conductivity was examined. It was possible to manufacture hot-pressed WC-graphene composites with oriented GNP(12) particles, however, the addition of graphene decreased both thermal and mechanical properties of the material.

3

New thermoplastic polyurethane elastomers based on sulfur-containing chain extenders

Kultys A., Puszka A.

Polish Journal of Chemical Technology

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2013

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Vol. 15, nr 4

65-70

EN

New thermoplastic polyurethane elastomers (TPUs) were synthesized by a one-step melt polyaddition from poly(oxytetramethylene) diol of M¯n = 2000 g/mol as the soft segment, 1,1’-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W®), and 2,2’-[methanediylbis(benzene-4,1-diylmethanediylsulfanediyl)]diethanol (diol E) or 6,6’-[methanediylbis(benzene-4,1-diylmethanediylsulfanediyl)]dihexane-1-ol (diol H) as unconventional chain extenders. The effects of the kind and amount of the polymer diol and chain extender used on the structure and properties of the polymers were studied. The polymers were examined by Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, Shore hardness and tensile testing. Both the adhesive and optical properties were determinated for a selected polymer. The obtained TPUs were amorphous, colorless, high-molar-mass materials. It was observed that the polymers with the diol E showed higher hardness and tensile strengths but smaller elongations at break than diol H-based ones. All of the polymers exhibited a relatively good thermal stability. Their temperatures of 5% mass loss were in the range 312-338°C.

4

Palność oraz inne właściwości materiałów i nanomateriałów elastomerowych. Cz. I. Nanokompozyty elastomerowe z montmorylonitem lub haloizytem

Rybiński P., Janowska G.

Polimery

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2013

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T. 58, nr 5

327-341

PL

Artykuł stanowi przegląd literatury uwzględniający doniesienia z badań własnych autorów, dotyczący stabilności termicznej, palności oraz właściwości mechanicznych nanokompozytów elastomerowych zawierających: glinkę montmorylonitową lub nanorurki haloizytu. Rozkład termiczny nanokompozytów elastomerowych rozpatrywano biorąc pod uwagę rodzaj, ilość oraz barierowość nanododatku, strukturę warstwy węglowej a także oddziaływania pomiędzy nanododatkiem a reaktywnymi grupami w elastomerze.

EN

The paper is a review of the literature, including the authors' own studies, concerning the thermal stability, flammability and mechanical properties of elastomeric nanocomposites containing montmorillonite clay or halloysite nanotubes. The thermal decomposition of elastomeric nanocomposites was investigated, taking into account the type and quantity of the nanoadditive, its barrier properties, the structure of carbon layer as well as the interactions between the nanoadditive and reactive groups in the elastomer.

5

Atomistic Studies of Fundamental Properties and Processes in Energetic Materials: Relevance to Mesoscale Initiation Phenomena

Sewell T. D.

Central European Journal of Energetic Materials

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2006

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Vol. 3, nr 1-2

19-38

EN

Genuine, physics-based understanding of initiation phenomena in plasticbonded explosives (PBXs) requires knowledge of the physics and chemistry at mesoscopic scales that are far larger than can be simulated directly using atomistic detail, yet far smaller than is directly resolvable in practical engineering scale continuum simulations. Initiation is determined by localization phenomena that arise due to the heterogeneous character of most explosive formulations. Indeed, the "average" temperature behind a weak shock is not a useful measure for understanding initiation phenomena; rather, it is the tails of the distributions in temperature, stress, and strain rates, localized to small, spatially distributed volumes in the material (hot spots), that dictate the outcome of a given loading event. Important factors for predicting hot spot formation and subsequent extinction or growth/coalescence include particle size, concentration, morphology, and void content; physical and chemical interactions between grains and binder; thermophysical and mechanical properties of the constituents and interfaces between them; and, of course, the inherent chemical stability of the explosive component(s) in the formulation. We are in the process of computing many of the thermophysical and mechanical properties required for a complete specification of constituent models for use in mesoscale simulations, wherein grains and binder in representative volumes of a PBX are spatially resolved and then studied within a continuum hydrodynamic framework. In addition to calculating specific properties of interest, we have recently undertaken a series of large-scale molecular dynamics simulations of energetic crystals to understand dissipation phenomena in dynamically loaded single- or poly-crystalline samples; for instance, plastic deformation and stress/energy localization mechanisms, phase transitions, and so on. Recent and ongoing work in these areas will be discussed, along with their specific relevance to emerging mesoscale simulation capabilities.

6

Modyfikacja właściwości tworzyw sztucznych oligomerycznymi ciekłymi kryształami

Majnusz J., Bortel K., Kurzeja L., Kurcok M., Szewczyk P., Marcinkowski A., Misztal M., Żak T.

Prace Naukowe Instytutu Technologii Organicznej i Tworzyw Sztucznych Politechniki Wrocławskiej. Konferencje

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2001

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Vol. 50, nr 23

151-154

PL

Ciekłe kryształy, będące substancjami o szczególnej budowie chemicznej, występujące w ich odmianie termotropowej w różnym stanie fizycznym w funkcji temperatury, są potencjalnie ciekawymi modyfikatorami tworzyw sztucznych. Kontynuacja wcześniej prowadzonych prac prowadzona była w kierunku modyfikacji podstawowych tworzyw sztucznych PS, PVC i EP dla poprawy ich właściwości transportowych i mechanicznych. PS stanowił dodatek umożliwiający otrzymanie materiału o cechach żelu, o właściwościach fazowych zdeterminowanych przez oligomeryczny ciekły kryształ występujący w znacznej przewadze w mieszaninie. Polepszenie właściwości mechanicznych PVC uzyskano stosując jako modyfikator fizyczny podstawiony chlorem oligoester ciekłokrystaliczny. W usieciowanym EP wykorzystano oligo- i polimeryczne ciekłe kryształy, zawierające grupy reaktywne, jako substancje reagujące z żywicą epoksydową.

EN

Liquid -crystalline, LC, oligo- or polyesters has been used for properties modification of known polymers. In order to obtain gel like membranes, a low melting mixture of oligoesters was used for swelling PS films. The 10% addition of a pentachloro-substituted tetraester well modified the properties of PVC, acting one hand as plastisizer, and on the other hand improving the mechanical strenght. Hydroxyl group terminated LC oligo(2-alkyl-1,4-phenylene terephthalate)s improved the impact strenght of crooslinked epoxides.

7

Synteza kopoli(estro- amidów) z wykorzystaniem alfa, omega-di(amino-propylo)oligotetrahydrofuranu i ich charakterystyka

Pietkiewicz D., Rosłaniec Z.

Polimery

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1999

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T. 44, nr 2

115-122

PL

Przedstawiono syntezę i charakterystykę nowych bezładnych kopoli(estro-amidów) (PAE) otrzymanych dwuetapową metodą trans-estryfikacji i polikondensacji w stanie stopionym. Do syntez zastosowano oligoeter zakończony grupami aminowymi [a,w-di(3-aminopropylo)oligotetrahydrofuran] o trzech różnych wartościach ciężaru cząsteczkowego (Mn = 750,1100 lub 2100 g/mol). Sekwencje oligoestrowe były zbudowane z oligo(tereftalanu butylenu) (PBT), Otrzymane kopoli(estro-amidy) poddano badaniom metodami różnicowej kalorymetrii skaningowej (DSC), dynamicznej analizy termomechanicznej (DMTA) oraz podstawowym badaniom właściwości fizycznych i mechanicznych. Na podstawie wyników DSC stwierdzono, że PAE charakteryzują się dwiema wartościami temperatury zeszklenia Tg (w obszarze nisko-i wysokotemperaturowym, co powiązano z dwufazowym charakterem tych produktów. Stała wartość Tg w obszarze niskotemperaturowym świadczy o stałym składzie fazy polieterowej bez względu na skład kopolimeru (rys. 4). Również analiza DMTA potwierdziła heterofazową strukturę PAE i związane z nią właściwości elastoplastyczne. Duże wydłużenie względne przy zerwaniu, duża elastyczność oraz maja twardość PAE zawierających 50-60% mas. oligoeterodiaminy o Mn=2100 są charakterystyczne dla elastomerów.

EN

Novel random copoly(ester-amide)s (PAE) were obtained in a two-step transesterification and polycondensation process carried out in the melt. The PAEs were obtained by using an oligoether with amine end-groups [a,w-di(3-aminopropyl)oligo_tetrahydrofuran] with three different molecular weights (Mn=750 g/mol; Mn=1100 g/mol; Mn=2100 g/mol). Oligo(butylene terephthalate) (PBT) was used as an oligo-ester sequence in PAEs. Thermal and mechanical properties of PAEs were examined by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and other standard physical methods. DSC disclosed two Tg temperatures in PAEs (one in the low and the other in the high temperature range), attributed to two phases existing in PAEs. The constant Tg -value in the low-temperature range indicates that, regardless of the composition of the polymer, the polyether phase has a constant composition. DMTA confirmed the hetero-phase structure of PAEs and the associated elastoplastic properties of PAEs. The extensive relative elongation at break, the high elasticity, and the low hardness of PAEs containing 50-60 wt. % of oligoether-diamine are characteristic for elastomers of Mn=2100.