Síntesis y caracterización de la mezcla polipropileno-poliestireno expandido (icopor) reciclado como alternativa para el proceso de producción de autopartes / Synthesis and characterization of expanded mixed polystyrene - polypropylene (styrofoam) recycled as an alternative for production process of autoparts

En el proceso de fabricación de autopartes se incluye el polipropileno (PP) como materia prima principal y la fibra de vidrio como insumo para la producción de ventiladores utilizados en los sistemas de refrigeración de los automotores. Los estándares de fabricación deben garantizar la resistencia de los productos en condiciones a las que estarán sometidos dentro del motor. Para lograrlo, el polipropileno es mezclado con fibra de vidrio en el proceso de inyección para aumentar la resistencia y la dureza del producto final, debido a que está expuesto a cambios de temperatura, choques con otras piezas, desgaste e impactos inesperados en el vehículo. Este estudio sintetizó y caracterizó un material obtenido a partir de la mezcla polipropileno puro-poliestireno expandido (EPS) (icopor) reciclado como una alternativa de aprovechamiento para el icopor dentro del proceso de fabricación de autopartes a modo de sustituto de la fibra de vidrio en el proceso de producción, siguiendo pasos como el tamizaje de los tamaños de material, la mezcla de los mismos, la obtención de probetas y la realización de ensayos mecánicos y térmicos. El objetivo fue comparar las propiedades mecánicas y térmicas del material obtenido (PP-EPS) con el material actualmente utilizado (PP-fibra de vidrio) para el que no se tenían estudios previos y de esta forma determinar la viabilidad de incorporación de un residuo a un proceso productivo y evitar su disposición directa favoreciendo el reciclaje del mismo. Las mezclas se caracterizaron mediante ensayos de tensión-deformación, dureza Shore A y análisis termogravimétrico (TGA) de los cuales se obtuvo favorecimiento en las propiedades térmicas y reducción de la resistencia mecánica en el uso de icopor, resaltando por supuesto el ahorro significativo en el cambio de insumos del proceso productivo.

Polypropylene (PP) as main raw material and fiberglass as input for the production of fans used in the cooling systems of motor is included in the process of manufacturing parts. Manufacturing standards must guarantee the resistance of the product in conditions that will be subject within the engine. To achieve this, the polypropylene is mixed with fiberglass in the injection process to increase the strength and hardness of the final product, as it is exposed to temperature changes, impacts with other parts, wear and unexpected impacts on the vehicle. This study synthesized and characterized a material obtained from the pure-polypropylene blend expanded polystyrene (EPS) (polystyrene) recycling as an alternative use for polystyrene in the auto parts manufacturing process as a substitute for fiberglass production process, following steps as screening media sizes, the mixture thereof, and obtaining specimens performing mechanical and thermal tests. The aim was to compare the mechanical and thermal properties of the material obtained (PP-EPS) with the material currently used (PP-fiberglass) for which they had no previous studies and thus determine the feasibility of incorporating a waste to a production in order to avoid direct disposal and thus promote the recycling process itself. The blends were characterized by stress-strain tests, Shore A hardness and thermogravimetric analysis (TGA) of which was obtained favoring the thermal properties and mechanical strength reduction in the use of polystyrene, of course emphasizing the significant savings in change of inputs in the production process.

Evaluación sanitaria de factores de riesgos físicos en viviendas Petrocasas bajo un cambio de cubierta / Health evaluation of physical risk factors in petrohouses after roof replacement

Introducción: el problema de la vivienda tiene un alcance mundial. La solución del déficit cualitativo y cuantitativo de la vivienda en Cuba transita a través de diferentes soluciones. Varios asentamientos del país se han erigido con vivienda industrial prefabricada de cloruro de polivinil ­PVC- conocidas por Petrocasas. Algunos estudios reportan estrés térmico en estas viviendas, vinculado a débil ventilación y calentamiento de cierres expuestos al sol. Objetivo: realizar una evaluación de salud ambiental en factores de riesgos físicos en el ambiente interior de las viviendas relativo a la intemperie, tras un cambio del material de cubierta. Método: se plantea un estudio experimental evaluativo de factores de riesgos físicos en el ambiente interior de las viviendas petrocasas a partir de una propuesta de modificación del material de la cubierta con la intención de reducir el estrés térmico de las mismas. Fueron edificadas con este propósito dos viviendas petrocasas con igual orientación de fachada principal y diferente cubierta; ;una fue sustituida por poliestireno expandido y la otra mantiene cubierta original (aluminio y papel de asfalto).Se evaluaron comparativamente factores de riesgos físicos: ruido, componente magnético del campo electromagnético de baja frecuencia, iluminación natural, artificial, ventilación y, principalmente, microclima para valorar la eficacia del cambio introducido. La evaluación estadística se efectuó por descriptores, modelos de regresión y espectro de potencia bivariado con los paquetes estadísticos SPSS v. 17.0 y Statistica 8.0. Resultados: la vivienda Petrocasa con cubierta de aluminio ­ asfalto presenta un clima interior algo más desfavorable al bienestar térmico que aquella de poliestireno; la ventilación en ambas resulta deficiente. Conclusiones: el cambio de material de la cubierta ligera de la vivienda Petrocasa proporciona un clima interior algo más favorable al bienestar de sus residentes(AU)

Introduction: the housing problem is global in scope. Solution to qualitative and quantitative housing deficit in Cuba has been addressed from various different perspectives. Several settlements in the country have been built with prefabricated industrial houses made of polyvinyl chloride (PVC). These are known as petrohouses. Some studies have reported thermal stress inside these houses, resulting from insufficient ventilation and the heating of roofs exposed to the sun. Objective: carry out an environmental health evaluation of physical risk factors present in the indoor environment of petrohouses as compared with the outside environment after roof replacement. Method: an experimental evaluative study was conducted of physical risk factors present in the indoor environment of petrohouses based on a proposal of modification of the roof material with the purpose of reducing thermal stress. For this purpose, two petrohouses were built with the same orientation of their main facade, but different roof material. One was roofed with expanded polystyrene, while the other retained its original roof (aluminum sheets and asphalt paper). The following physical risk factors were evaluated comparatively: noise, magnetic component of the low frequency electromagnetic field, natural and artificial lighting, ventilation, and mainly microclimate, to evaluate the efficacy of the change made. Statistical evaluation was conducted with descriptors, regression models and bivariate power spectrum, using the statistical software packages SPSS v. 17.0 and Statistica v. 8.0. Results: indoor environment in the petrohouse with an aluminum-asphalt roof is somewhat more unfavorable in terms of thermal welfare than in the polystyrene-roofed house. Ventilation is deficient in both. Conclusions: roof replacement in petrohouses provides an indoor environment somewhat more favorable to the welfare of dwellers(AU)

Viabilidade do sistema de produção de mudas em bandejas em três cultivares de cebola / Viability of onion seedling production on polyestyrene trays in three cultivars

O presente trabalho foi conduzido em Ponta Grossa (PR), com o objetivo de avaliar a viabilidade do sistema de produção de mudas em bandejas, comparativamente ao sistema convencional, em canteiros, em três cultivares de cebola. O delineamento experimental foi o de blocos casualizados com três repetições. Os tratamentos foram arranjados segundo esquema fatorial 3 x 3, sendo três tipos de mudas (de bandeja com 200 e com 288 células e da sementeira) e três cultivares (Mercedes, Bola Precoce e Crioula). A produção de mudas em bandejas foi conduzida sob cultivo protegido e da sementeira em ambiente natural. A semeadura ocorreu no dia 15/05/2004, nas bandejas e na sementeira. Aos 57 dias, as mudas foram avaliadas e transplantadas em parcelas com quatro fileiras de plantas arranjadas no espaçamento de 0,40 x 0,08m, perfazendo um estande de 312.500 plantas.ha-1. A colheita foi realizada de acordo com a maturação das plantas. Após a cura, avaliou-se a produtividade de bulbos e foram calculados os custos de produção dos diferentes tipos de mudas e a sua viabilidade. Observou-se que as mudas provenientes de bandejas apresentaram superioridade quando comparadas às da sementeira, obtendo destaque as obtidas em 200 células. A qualidade superior dessa muda refletiu-se no desempenho posterior, obtendo-se maior rendimento de bulbos com mudas de bandejas de 200 células. O desempenho foi intermediário, quando proveniente de bandejas de 288 células e inferior, quando a muda usada foi de sementeira. Destaca-se que o aproveitamento de mudas da sementeira durante a seleção foi baixo (50 por cento), e o custo para sua produção é alto quando se utiliza semente de híbrido, comparável ao custo de cultivar de polinização aberta em bandejas de 288 células. As cultivares mais produtivas foram Crioula e Mercedes. A produção de mudas em bandejas, principalmente na de 200 células, é viável e representa uma alternativa para aumento da produtividade no cultivo da cebola...

The present trial was realized in Ponta Grossa (PR) and aimed to evaluate the viability of onion seedling production in polyestyrene trays, compared to conventional system on seedbed, using three cultivars The experimental design used was a randomized block with three replications. The treatments were arranged in a factorial scheme 3x3, being three seedlings type (from trays with 200 and 288 cells and from seedbed), and three cultivars (Mercedes, Bola Precoce and Crioula). Seedlings production on trays were realized under protected cultivation and seedlings from seedbeds produced in the field. Seeds were sowed in May,15th. At 57 days the seedlings were evaluated and then transplanted in plots with four rows and plants arranged in 0,40x0,08m, with 312.500 plants.ha-1. The harvest was realized according to the plant maturation stage. Bulbs were dried and then yield were evaluated. The production cost and seedlings viability were calculated. It was observed the seedlings from trays were superior when compared to seedlings from seedbed, mainly those from 200 cells.This higher seedling quality reflected on later performance obtaining the highest yield from trays of 200 cells. It was intermediary with 288 trays and lower from seedbed seedling. It was observed low seedling useful from seedbed during the selection process (50 percent). In the case of hybrid the cost of seedling production in seedbed was high, almost comparable to seedling production of open pollinated cultivars on trays of 288 cells. The best cultivars were Crioula and Mercedes. Seedlings production on trays mainly on 200 cells showed viability and represents an important alternative to increase onion yield in a competitive market.