Influencia del proceso de reciclado sobre las propiedades de los materiales compuestos obtenidos por inyección de poliestireno reforzado con fibras lignocelulósicas

The objective of this research is to study the influence of several recycling cycles on the mechanical properties of four different materials made by the injection of polystyrene. The four materials studied have different characteristics. The first one is polystyrene (PS), the second one is polystyrene reinforced with hemp fibers (PSf), the third one is polystyrene reinforced with hemp fibers modified with AKD (PSft) and the last one is polystyrene reinforced with fiberglass (PSfv). With all these materials tensile strength, bending, hardness and impact is measured. After the measurement of these physical properties, materials are recycled to obtain new injection samples, and its physical properties are measured again. This process is repeated during 24 cycles. After each recycling cycle material physical properties are related with polystyrene molecular weight, melt flow, FTIR spectra and DSC. From reinforced materials, fibers are recovered and through microscopy and image analysis they are characterized to study the influence that recycling has on its structure.

Andamios porosos

222 p.

Las actividades comunicativas en los materiales didácticos

The ability to communicate orally in a foreign language is fundamental and highly evaluated by both students and teachers. Therefore it is important that educational materials can provide communicative activities that improve this ability. A study of educational materials for young French learners revealed that the activities aimed to practice oral communication in fact were not really communicative. This investigation analyzes three educational materials for beginners in Spanish. The purpose is to see which kinds of activities the materials can offer for practice of oral and interactive communication, to compare them with educational theories and the Swedish curriculum and to detect similarities with the former study. The results show that the majority of the activities used in the materials, are not really communicative, they are mostly based on prepared phrases and there are few possibilities for creativity.

Industria minera de los materiales de construcción. Su sustentabilidad en América del Sur

Incluye Bibliografía

Programas de construcción de viviendas en los países del Istmo Centroamericano para 1962-1963 y su relación con los materiales de construcción requeridos

Incluye Bibliografía

Los materiales de construcción: base industrial de la producción de viviendas en América Latina y el Caribe

Incluye Bibliografía

La durabilidad de los materiales constructivos

Colección Materiales y Técnicas de Construcción

Propiedades de los materiales

Colección Materiales y Técnicas de Construcción