Recycling of Thermoset Materials and Thermoset-Based Composites: Challenge and Opportunity

Thermoset materials and their composites are characterized by a long life cycle with their main applications in aircrafts, wind turbines and constructions as insulating materials. Considering the importance of recovery and valorization of these materials at their end-of-life, avoiding landfilling, the interest concerning their recycling grows continuously. The thermoset materials and their composites, to be successfully recovered and valorized, must degrade their three-dimensional structures and recover the mono-oligomers and/or fillers. The thermoset materials could successfully degrade through thermal treatment at different temperatures (for example, above 1000 degrees C for incineration, ca. 500 degrees C for oxidation/combustion of organic constituents, etc.), chemical degradation by catalyst, irradiation with or without the presence of water, alcohol, etc., and mechanical recycling, obtaining fine particles that are useful as filler and/or reinforcement additives. Among these recycling methods, this mini-review focuses on the formulation and recovery method of innovative thermoset with in-build recyclability, i.e., materials having chemical links that could be degraded on-demand or containing dynamic covalent bonds to have re-processable and/or recyclable thermoset. This issue could be considered the future perspective in developing novel thermoset materials. The aim of this review is to get an overview of the state of the art in thermoset recycling and of the most commonly used thermoset composites, recovering valuable reinforcing fibers. Additionally, in this work, we also report not only known recycling routes for thermoset and thermoset-based composites, but also new and novel formulating strategies for producing thermosets with built-in recyclability, i.e., containing chemical-triggered on-demand links. This mini-review is also a valuable guide for educational purposes for students and specialized technicians in polymer production and recycling

Особливості перебігу процесів психофізіологічної адаптації та формування психофізіологічних функцій організму учнів сучасної школи

В ході проведених досліджень встановлені особливості перебігу процесів психофізіологічної адаптації і, отже, процесів формування психофізіологічних функцій учнів 14–17 років в умовах навчання в старших класах сучасної школи. На підставі вивчення провідних показників функціонального стану вищої нервової діяльності, зорової сенсорної системи та сомато6сенсорного аналізатора виявлений достатньо стабільний характер адаптаційних перетворень психофізіологічного змісту впродовж часу перебування в старших класах сучасної школи. Визначений цілий ряд статевозумовлених тенденцій щодо динамічних змін досліджуваних показників протягом часу спостережень, насамперед, з боку показників врівноваженості нервових процесів, а також характеристик функціонального стану зорової сенсорної системи (критична частота злиття світлових миготінь) та сомато-сенсорного аналізатора (координація рухів). Найкращі показники щодо ступеня вираження серед дівчат реєструвались переважно у віці 17 (більшість показників функціональних можливостей вищої нервової діяльності) та 15 років (врівноваженість нервових процесів і координаційні здібності), натомість найгірші (майже за всіма досліджуваними функціями) – у віці 14 років. Разом з тим серед юнаків найкращі показники спостерігались переважно у віці 17 (більшість показників функціональних можливостей вищої нервової діяльності) та 14 років (критична частота злиття світлових миготінь і координаційні здібності), водночас, найгірші – у віці 16 та, що дуже цікаво, 17 років, тобто заключний період перебування у школі відзначався надзвичайно суперечливим пере бігом процесів психофізіологічної адаптації і, отже, формування такого психофізіологічного потенціалу особистості, що забезпечував високий ступінь функціональної готовності до успішного навчання в загальноосвітньому закладі

Polar Wax as Adhesion Promoter in Polymeric Blend Films for Durable Photovoltaic Encapsulants

Technological developments in the solar photovoltaic field must guarantee the high performance and low deterioration of solar cells in order for solar power plants to be more efficient and competitive. The solar cell needs comprehensive protection offered by a polymeric encapsulant, which improves UV stability, reduces water and moisture absorption, reduces oxygen and vapor permeability and enhances mechanical resistance. Moreover, high transparency and adhesion yields improved the solar panel performance. The current work analyzes polymeric films based on poly(ethylene-co-vinyl acetate) (EVA) and polyolefin (PO) for photovoltaic encapsulant use (the high temperature resistance is improved by adding PO to EVA, as investigated and documented before). To enhance the mechanical resistance and optical properties of the investigated matrices, a crosslinking agent, an adhesion promoter and stabilizing agents have been incorporated in both EVA and EVA/PO systems. The adhesion promoter is a polar wax–silane-free agent; the absence of the silane function allows the integrity of the module to be maintained over time. All samples were characterized through mechanical and rheological analysis, and their long-term UV stability was investigated by accelerated ageing and by FTIR and UV–vis spectroscopy. The obtained results suggest that the presence of a crosslinking agent, an adhesion promoter and stabilizers in EVA/PO-based films allows for the achievement of the required features for the encapsulants, showing mechanical and rheological behavior similar to those of EVA containing the same additives

Características de tres pastizales bajos con distinto periodo de descanso

In an upland region with short grassland in the Dpto Loventué- La Pampa (Lat-.36°50' S Long.65°18' W) we compared three areas-. Two of them were exclosures of 28 and 14 years; the third had a rest of twelve months every other year. The three communities were similar in floristic composition but different in the values of abundance-cover of their principal species. Vegetation cover had a maximum in the exclosures and a minimum in the area that had a rest of twelve months every other year. In the three areas the frequency of dominants and codominants species ranged among 90-100%. Standing crop reached 320 gMS/m2 in the oldest exclosure and 150 gMS/m2 in the area with a rest of twelve months every other year. Flower stalk numbers, culm lenght and crown diameter were great in the 14 years exclosure·.koeleria permollis a decreaser palatable specie was codominant only in the 28 years exclosure. Poa ligularis another decreaser desiderable specie codominated in the 14 years exclosure. In the area with a rest of twelve months every other year was dominant Piptochaetium.En una región con pastizal bajo del departamento, La Pampa (lat·.36°50' S Long'. 65°18' W) se analizaron las diferencias entre tres áreas. Dos de ellas eran clausuras de 28 y 14 años. La tercera tuvo en los últimos años un descanso de doce meses, año por medio. Las tres áreas son similares en composición florística, pero difieren en los valores de abundancia-cobertura de sus especies principales. La cobertura de la vegetación tuvo un máximo en las dos clausuras y un mínimo en el área con descanso de doce meses, año por medio. La frecuencia de las especies dominantes y codominantes vario del 90 al 100%. La fitomasa aérea alcanzó a 320 gMS/m2 en el área no pastoreada durante 28 años y de150 gMS/m2 en el área con un descanso anual, año por medio. Los valores de altura de cañas, altura verde y diámetro de corona fueron mayores en la clausura de 14 años. Koeleria permollis una especie decreciente codominó solamente en la clausura de 28 años. Poa ligularis otra especie decreciente, deseable, codominó en la clausura de 14 años y Piptochaetium napostaense domino en el área con un descanso de doce meses, año por medio

Disponibilidad forrajera de un pastizal de Pappophorum caespitosum Fries en el sudeste de La Pampa

Standing crop of a Pappophorum caespitosum "pasto blanco" grassland was determined in the southeastern of La Pampa Province, Dpto. Caleu Caleu, Ea. Los Guadales. Lat. 38°13'S Long. 64°18' W. At the end of autumn (June) the grassland reached 310 gMS/m2 Pappophorum caespitosum, the principal specie totalized 224 gMS/m2. In spring (October) Medicago minima "Trébol de carretilla" y Erodium cicutarium "alfilerillo", two annual species gave 248 gMS/m2. The vegetation cover was high in the grassland during all the year. "Pasto blanco" had 100% of annual frequency and "Trébol de carretilla" y "alfilerillo" the 90%.Se determinó la fitomasa aérea mensual de un pastizal de Pappophorum caespitosum "pasto blanco" en el sudeste de La Pampa, Ea. Los Guadales, Dpto. Caleu Caleu. Lat. 38°13' S Long. 64°18' W. El pastizal alcanzo a fines de otoño 310 gMS/m2. Pappophorum caespitosum la especie dominante, totalizó 224 gMS/m2; Medicago minima "trebol de carretilla" y Erodium cicutarium "alfilerillo" brindaron 248 gMS/m2 en Octubre (primavera). La cobertura de la vegetación fue alta durante todo el año. "Pasto blanco" tuvo el 100% de frecuencia anual y trebol de carretilla y alfilerillo el 90%

Tres pastizales ubicados en una catena topográfica en el sudeste de La Pampa, Argentina

This study was made in the Ea. Los Guadales-Department Caleu- Caleu, in the southeastern region of La Pampa where the landscape is mainly formed by one plateau, slopes and depressions. Three different grasslands were studied in a soft slope, along a topographical profile. In the upper site there is a perennial winter grasslands dominated by Stipa tenuis a short, native grass. Standing crop reached 215,5 gDM/m2. In the slope it grows an intermediate summer grassland dominated by Pappophorum caespitosum, a perennial warm grass. Standing crop totalized 310,5 gDM/m2. In the botton landthere is an intermediate winter grassland dominated by Stipa brachychaeta a perennial native species. Standing crop reached 469,1 gMS/m2.Este estudio fue hecho en el sudeste de La Pampa-Dpto. Caleu-Caleu - Ea. Los Guadales, en una región donde el paisaje está formado por mesetas, pendientes y bajos. En una suave pendiente se estudiaron tres pastizales diferentes, a lo largo de una catena topográfica. En la parte alta hay un pastizal bajo, invernal, dominado por Stipa tenuis, una especie baja, nativa. La fitomasa aérea acumulada totaliz6 215,5 gMS/m2. En la pendiente crece un pastizal intermedio, estival dominado por Pappophorum caespitosum, una gramínea perenne, estival. La fitomasa aérea fue de 310,5 gMS/m2. En el bajo hay un pastizal inter medio, dominado por Stipa brachychaeta, una especie perenne, nativa. La fitomasa aérea totalizó 469,1 gMS/m2

Relevamiento de fitomasa aérea del área del vaso de la presa embalse Casa de Piedra

In an area of shrublands in the southwest of La Pampa we determined woody aerial phytomass and density of shrubs. The results obtained in the area I (Aquatic), II (amphibiam) and III (rarely inundated) were 11.000, 12.000 and 13.000 k/ha respectively. Density of Larrea cuneifolia were 979, 1.686 and 1.736 pI /ha in the areas I, II y III. Atriplex lampa had 670. 1079 and 933 pI/ha. Larrea divaricata had 357, 894 and 913 pl/ ha in the threee different areas. The principal units of vegetation were: a shrubland of Larrea cuneifolia, a shrubland of Larrea divaricata and a Heathland of Suaeda divaricata and Atriplex ondulata. A tall grassland of Cortadera selloana was present on the sandy soils.Se determinó fitomasa aérea y densidad de arbustos en un área del sudoeste de La Pampa. Los resultados obtenidos fueron de 11.000. 12.000 Y 13.000 k/ha en las áreas I (acuática) II (anfibia) y III (raramente inundable) respectivamente. La densidad de Larrea cuneifolia (especie dominante) fue de 979. 1.686 Y 1.736 pI/ha en las areas I, II y III. La densidad de Larrea divaricata fue de 357, 894 Y 913 pI/ha mientras que la de Atriplex lampa fue de 670, 1.079 Y 933 pI/ha. Las principales unidades de vegetaci6n fueron un arbustal de Larrea cuneifolia, uno de Larrea divaricata y un matorral de Suaeda divaricata y Atriplex undulata. Un pastizal alto de Cortadera selloana estaba presente en áreas arenosas

Structure-properties relationships of polyhedral oligomeric silsesquioxane (POSS) filled PS nanocomposites

The polyhedral oligomeric silsesquioxane (POSS) additivated polystyrene (PS) based nanocomposites were prepared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocomposites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS matrix was estimated by the calculated theoretical solubility parameters, considering the Hoy’s method and by morphology analysis. Minor difference between the solubility parameter of POSS and the matrix means better compatibility and no aggregation tendency. Furthermore, the POSS loading leads to a decrease of the rigidity, of the glass transition temperature and of the damping factor of the nanocomposite systems. The loading of different POSS molecules with open cage leads to a more pronounced effect on all the investigated properties that the loading of the POSS molecules with closed cage. Moreover, the melt properties are significantly influenced by the type of inorganic framework, by the type of the pendent organic groups and by the interaction between the POSS organic groups and the host matrix, while, the solid state properties appears to be influenced more by the kind of cage