Shape memory epoxy vitrimers based on DGEBA crosslinked with dicarboxylic acids and their blends with citric acid

Thermosetting polymers were synthesized from a commercial epoxy resin (diglycidyl ether of bisphenol A, DGEBA) and tricarboxylic (citric, CA) and different dicarboxylic (sebacic, SA and glutaric, GA) acids. Crosslinking of DGEBA-SA and DGEBA-GA systems was achieved using excess epoxy, which was homopolymerized after all the acid groups were consumed. It was found that the properties of the material depend on the diacid length and on the excess epoxy, and with the proper formulation, vitrimers with Tg values ranging from 51 °C to 62 °C, and a high rate of stress relaxation (less than 1 h at 160 °C to achieve 63% of relaxation) could be obtained. Notably, using a mixture of tri-functional CA with SA allowed a reduction in the epoxy excess while maintaining a high Tg value and faster stress relaxation. Three of the formulations were selected and their shape memory performance was studied. Good shape fixity and shape recovery ratios (>99%) were obtained, which indicate an overall good shape memory performance. These properties can be used to create different permanent and temporary shapes on a thermosetting polymer obtained from widely available and affordable raw materials.Fil: Altuna, Facundo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Williams, Roberto Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Student Usage and Perceptions of Digital Devices in the Classroom and While Driving

The purpose of this study is to examine Central Washington University students’ use of electronic devices for non-class related purposes and while driving. For the purposes of the study, electronic devices are defined as cellphones, tablets, laptops, and any other devices that are non-essential to the classroom environment, and non-classroom purposes are defined as any non-course specific activities performed on an electronic device during lecture. The survey has two parts, the first focusing on electronic device usage in the classroom, and the second focusing on electronic device usage while operating a vehicle. The survey is administered online, and focuses on students over the age of eighteen. Psychology students represent the largest demographic, but the survey also draws from numerous other departments. Preliminary results are similar to those of studies regarding electronic device usage conducted at other universities, and indicate that the use of electronic devices is prominent in Central Washington University classrooms. These findings highlight how important it is for professors to understand students’ perceptions toward the use of electronic devices in the classroom for non-class related purposes

Nanomateriales creados en la Argentina

En los últimos años se han fabricado computadoras más rápidas, pantallas más delgadas, más brillantes y más livianas, motores más eficientes. Alcanza con mirar a nuestro alrededor para darnos cuenta de que nos encontramos rodeados por objetos que han cambiado nuestras vidas. Están hechos de gran diversidad de materiales, generados por técnicas basadas en avances del conocimiento de la física y la química de la materia. También se han puesto a punto en tiempos recientes nuevos métodos de diagnóstico y tratamiento de enfermedades, de recuperación de ambientes contaminados y de generación y almacenamiento de energía. Muchos de esos notables progresos tecnológicos han sido posibles gracias al desarrollo reciente de los nanomateriales. El objetivo de este artículo es discutir qué son y para qué sirven, y dar ejemplos de algunos que fueron elaborados en la Argentina para cumplir determinadas funciones.Fil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Williams, Federico Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Evaluation of impact of beam size on fibre Bragg grating fabrication

Fabrication of gratings has gone a long way since the onset by Kenneth Hill in 1976. Basic fabrication techniques such as holographic and phase-mask which have distinguishing advantages (variable wavelength, and high repeatability consecutively) have since been modified in an effort to combine the advantages of both methods. These basic methods are inherently simple and have few controls, they have been combined and modified over time to enable the possibility of fabricating gratings with complex modulation index and phase profiles

Too much ‘stuff’ and the wrong space: A conceptual framework of material possessions

Space for living in new build houses in the UK is at premium and households have more stuff than ever before. The way this stuff is accommodated in dwellings can significantly affect residents’ quality of life and well-being. This paper presents a new conceptualisation of material possessions that could be of use to those involved in housing design. Three universal characteristics of material possessions; value, temporality and visibility are used to identify the space in the home that possessions might require. A conceptual framework that integrates these characteristics with spatial information about the interior of the home is developed. The paper argues that the conceptual framework could help designers, policymakers and house builders to better understand first the nature of material possessions, and second how those possessions could be accommodated in contemporary homes, ultimately supporting improved quality of life and wellbeing for households

Exploring the Potential for 3D Printing: Medical Logistics in Operational Environments

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