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Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

RESUMO Neste trabalho foram utilizados resíduos de madeira de Eucalyptus grandis em forma de cavacos e plástico pós-consumo tipo polietileno de baixa densidade (PEBD), nas proporções de 40%/ 60%, 50%/50% e 60%/40% de madeira/plástico no composto. Foi observada uma diferença entre a massa específica aparente (MEA) dos tratamentos, sendo necessário realizar uma análise de covariância em função da densidade para a correta interpretação dos resultados. Os tratamentos com maior percentual de PEBD na sua composição foram os que apresentaram melhor desempenho. De forma geral os valores das propriedades mecânicas atingiram os requisitos mínimos da norma ANSI A208.1, usada para classificar chapas de aglomerado, com exceção do MOR e do MOE do tratamento onde uma menor proporção de plástico foi usada.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

O pinhão é um alimento de grande importância econômica e gastronômica no Brasil, mas com dificuldade de conservação pós-colheita. No presente estudo avaliou-se as características dos pinhões armazenados no ambiente doméstico, utilizando-se embalagens de polietileno (PEBD) e juta, sob temperatura ambiente ou refrigeração. Foram realizadas análises, a cada 15 dias (durante 90 dias), da composição centesimal, umidade, atividade de água, perda de massa, cor de casca, cor do endosperma, pH, açúcares solúveis, teor de amido e quantificação de sementes avariadas. O pinhão foi melhor conservado em embalagem de polietileno sob refrigeração, mantendo a umidade, menor perda de massa e cor. Embalagens de juta favoreceram maior degradação da cor e aumento do apodrecimento e brotação. Sugere-se que é viável a comercialização de pinhões mantidos sob refrigeração por até três meses, em embalagem de polietileno.

Araucaria angustifolia seeds are considered important food product of Brazilian diet but with post-harvest conservation problems. In the present study, the characteristics of the seeds stored in the domestic environment and under refrigeration, were evaluated. The experiment used low-density polyethylene and jute packaging. Analysis of centesimal composition, moisture, water activity, mass loss, skin color, endosperm color, pH, soluble sugars, starch content and quantification of damaged seeds, were carried out every 15 days for 90 days. The seeds were better preserved in polyethylene packaging under refrigeration, keeping moisture, less loss of mass and color. Jute packaging promoted color degradation and increased rotting and sprouting. It is suggested that the commercialization of Brazilian pine seeds could be viable if kept for up to three months under refrigeration in polyethylene packaging. [ABSTRACT FROM AUTHOR]

In the following work, synthesized polyethylene nanocomposites combined with a metallocene zirconium catalyst (PEZr) with 1 and 3 % multi-walled carbon nanotubes (MWCNT) were prepared. Maleic anhydride functionalized polyethylene nanocomposites (PEZr-g-MAH) and 4-aminopyridine functionalized polyethylene (PEZr-g-MAH / 4ampy) with 1 % NTsC were also prepared. All nanocomposites were characterized by: Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC); Self-nucleation (SN) and Thermal Fractionation by Successive Self-nucleation and annealing (SSA) experiments. The FTIR spectrum of the PEZr-g-MAH/1 %NTsC nanocomposite showed displacement of some absorption bands that increased a higher wave of numbers and that could occurred due to the interaction between the MWCNT and the carbonyl group of the anhydride and acid function of functionalized PE; while, in the PEZr-g-MAH / 4Ampy /1% NTsC nanocomposite, the intensive increment of the bands at 1097 and 1019 cm-1 was visualized. Non-isothermal DSC scans demonstrated the property of nanotubes to act as nucleating agents on the matrix of all the polymers studied. The study by SSA, together with the evaluation of the melting peaks using the software Peakfit 4.12, indicates that a redistribution of the lamellar thicknesses of the fraction with the highest melting temperature, speculating that it is possible the interactions of the π-π type between the pairs of free electrons of the pyridine ring of 4-Ampy and the electron cloud of MWCNTs. [ABSTRACT FROM AUTHOR]

Ahuyama (Cucurbita moschata) is recognized by its nutritional value, as it is composed of vitamin A, carbohydrates, phosphorus and minerals. Also, for its content of 45 % of total carotenoids; 66 % of β-carotene; 33 % of α-carotene, and 44 % of lutein. However, its high amount of water, about 90%, is conducive to bacterial and/or fungal growth reducing its useful life. Present study evaluated every three days, over a total of 12, three repetitions and three replications of freshly cut green bolus squash variety. Physicochemical attributes like weight, color, firmness, and respiration rate were observed, as well as those microscopic (MOAR and MET); bromatological, and microbiological characteristics to 4 different treatments as follow: SN (control sample); CV (Vinyl wrap); CR (coated with cassava starch and 1 % thyme essential oil); and CB: (binary system with natural source coating and Vinyl wrap) under environmental conditions of 19 °C temperature and 77,75 % average humidity. Vinyl wrap treatment exhibited lower weight, firmness loss, fewer respiration rate loss, and had better color stability. Control and coated samples showed higher sugar and moisture content but lower ash and protein. Additionally, samples with coated and uncoated stretch film registered minor fungal growth. Fresh cut squash could be properly preserved through the use of low-density polyethylene films (vinyl wrap), allowing to effectively delay the course of quality loss because of handling operations. [ABSTRACT FROM AUTHOR]

La contaminación por microplásticos (MPs) de tamaño menor a 5 mm ha tomado relevancia en los últimos años debido a su impacto en los ecosistemas. En Guatemala, se carece de información relacionada con MPs, por lo que este estudio tuvo como objetivo evaluar la abundancia y características de MPs en cuatro playas del Pacífico de Guatemala, Ocós, Tulate, Sipacate y Las Lisas. Se colectaron muestras de arena en mayo y octubre de 2019. Los MPs se aislaron y se clasificaron por forma, y el tipo de polímero se identificó a través de un equipo de espectroscopia infrarroja con transformada de Fourier (ATR-FTIR). La abundancia expresada en MPs/m2 en mayo fue de 25.6, 5.6, 0.8 y 0 MPs/m2 para Tulate, Las Lisas, Ocós y Sipacate; mientras que en octubre fue de 59.6, 23.2, 17.6 y 17.6 MPs/m2 en Tulate, Ocós, Las Lisas y Sipacate. Fragmentos, foam, pellets y láminas fueron las formas predominantes de MPs que se encontraron en las playas. El análisis por ATR-FTIR muestra que los principales polímeros identificados en las playas son polietileno, poliestireno y polipropileno. Los resultados de este estudio indican que las playas del Pacífico de Guatemala están contaminadas por MPs de diferentes tipos de polímeros. Además, estos resultados ofrecen información importante a los responsables de la toma de decisiones sobre la eliminación y el manejo de la basura plástica marina.

El abdomen abierto es una técnica quirúrgica en la cual dejamos la cavidad abierta cubriendo los órganos para el manejo de diferentes entidades clínico-patológicas. Materiales y métodos: Se evaluaron prospectivamente 14 pacientes entre febrero del 2018 a febrero del 2020, tratados con técnica de abdomen abierto contenido con Bolsa de Bogotá en el Servicio de Cirugía del Hospital Militar Central. Resultados: La edad promedio fue de 49 años, y el 79% fueron del sexo masculino. Fueron indicaciones para el manejo con abdomen abierto: Sepsis abdominal, control de daños, hipertensión abdominal y second look. En los pacientes con abdomen abierto por control de daños los órganos más frecuentemente lesionados fueron: Lesión esplénica con perforación de colon trasverso y lesión hepática con perforación duodenal. El número de reintervenciones promedio fue de 2,4 por paciente. Todos los pacientes estuvieron en Unidad de Cuidados Intensivos, con un promedio de 15 días. Las complicaciones encontradas: pacientes con fistula intestinal 21,4% y óbitos 21,4%. En 7 pacientes se utilizó en forma concomitante el sistema de aspiración al vacío. Conclusiones: El manejo del abdomen abierto contenido con Bolsa de Bogotá es una técnica simple para nuestro medio debido a su utilización con material de bajo costo como el polietileno obteniendo resultados satisfactorios.

This article studies the influence of the tensile speed when testing plastic products used to transport containers that may contain various liquids (drinking water, windshield fluid, cleaning agents, etc.). This case study was conducted on certain parts, generally called "handles", which are basically plastic items obtained largely from recycled technological waste resulting from the injection process of various packaging related to the food industry polyethylene caps and lids more precisely. During the handling and transport process, these parts are subjected to various static stresses, therefore, a minimum mechanical resistance is required. Fatigue stress has not been performed due to a limited number of duty cycles. To determine these quality characteristics, multiple measurements of tensile strength and elongations were performed at different traction speeds, measurements that have been validated on the market for several years. We have observed that testing speed over 500 mm/min is not necessary because the tensile strength values do not vary significantly. These results are very important in determining the constructive form of these products and the methods for validating quality indicators. Also, we have proposed to identify a method able to assess the mechanical performance of the product used in nonstandard conditions. The study can be used for a much wider range of similar applications in the plastics industry. [ABSTRACT FROM AUTHOR]

Copyright of Diversitas Journal is the property of Diversitas Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A acumulação de partículas de plástico em ambientes aquáticos é acarretada pela produção e uso em grande escala, somada à destinação incorreta enquanto resíduo. Esses pequenos fragmentos, denominados microplásticos (MP), são assunto emergente e considerados um problema mundial, podendo afetar organismos e seus mecanismos. O Litoral Norte do Rio Grande do Sul não possui registros científicos que revelem MP em águas estuarinas. O Sistema Estuarino Tramandaí-Armazém (ETA) recebe grande pressão antrópica, especialmente devido ao aglomerado urbano causado pelo turismo, pelos múltiplos usos de suas águas e por ser parte final receptora de águas de toda a Bacia Hidrográfica do Rio Tramandaí (BHRT). Nesse contexto, o objetivo desse estudo foi avaliar a presença de MP nas águas das lagunas Tramandaí e Armazém, visando classificá-los quanto à sua composição polimérica. Além disso, buscou-se estabelecer uma relação entre a ocorrência de MP e a qualidade da água. Os resultados evidenciam ser uma área que já apresenta contaminação por MP, sendo que na Laguna do Armazém foi contabilizado um total de 240 und/100 m³ e na Laguna Tramandaí foram determinados 225 und/100 m³ de MP. Destaca-se a predominância de PE, PP e PET/PVC que estão estreitamente vinculados às atividades desenvolvidas na região, como a pesca e a ocupação urbana em si. Contudo, não foi possível estabelecer uma relação da presença de MP com os parâmetros de qualidade da água. Embora esteja comprovada a contaminação por MP nessa área estuarina, uma avaliação de mais longo período é interessante e pode, inclusive, indicar o efeito, por exemplo, da ocupação massiva durante o veraneio.

La ahuyama (Cucurbita moschata) se caracteriza por su valor nutritivo, especialmente por su contenido de vitamina A, carbohidratos, fósforo y minerales. También, por poseer 45 % de carotenoides totales, 66 % de β-caroteno, 33 % de α- caroteno y 44 % de luteína. Su elevado porcentaje de agua cercano al 90 % es propicio para el crecimiento bacteriano y/o fúngico disminuyendo su vida útil. Este estudio evaluó, cada tres días durante un total de 12, con tres repeticiones y tres réplicas, las características fisicoquímicas (peso, color, firmeza, tasa de respiración); microscópicas (MOAR y MET), bromatológicas y microbiológicas, de ahuyama variedad bolo verde troceada en fresco. 4 tratamientos: SN (muestra testigo); CV con vinipel; CR con recubrimiento de almidón de yuca y aceite esencial de tomillo al 1 %; y CB con sistema binario (recubrimiento de fuente natural y vinipel) a una temperatura de 19 °C y humedad media de 77,75 %. Los tratamientos con película de vinilo arrojaron menor pérdida de peso y firmeza, menor tasa de respiración y mayor estabilidad en el color, en tanto que las muestras testigo y recubiertas, arrojaron mayor contenido de azúcares y humedad, pero menor cantidad de proteína y cenizas. Adicionalmente, las muestras con vinipel, con y sin recubrimiento, registraron un menor crecimiento fúngico. La ahuyama troceada en fresco puede conservarse de forma adecuada mediante el uso de películas de polietileno de baja densidad (vinipel), que permiten retrasar de manera efectiva los procesos de pérdida de calidad inducidos por las operaciones de corte y manipulación.

Con la agricultura protegida se resguardan las plantas de las condiciones climáticas adversas y se modifica la radiación solar que incide sobre ellas, con el propósito de mejorar su productividad. Por lo que, el objetivo de este estudio fue evaluar el efecto del material y color de cuatro cubiertas de invernadero, en la tasa y características espectrales de la radiación que se transmite y su relación con el contenido de clorofila, crecimiento y rendimiento de un cultivo de chile poblano (Capsicum annuum L.) variedad Ébano. El estudio se realizó en cuatro macro túneles de forma ovalada de 4 m de ancho, 2.5 m de alto y 12 m de longitud. La cubierta de tres túneles fue de láminas de policarbonato de color rojo, azul y translúcido, el otro se cubrió con polietileno difuso de alta densidad. Las características espectrales de la radiación solar que se transmitió en cada cubierta se determinaron con un espectro radiómetro; mientras que, la tasa de radiación fotosintéticamente activa (PAR) dentro y fuera de los túneles, se obtuvo con sensores quantum. Los resultados del estudio mostraron que las plantas que crecieron bajo las láminas de policarbonato de los diferentes colores, tuvieron mayor contenido de clorofila que las del polietileno de alta densidad y las de campo abierto. Debido a una menor incidencia de radiación fotosintéticamente activa (PAR) y casi nula transmisividad de la radiación de 400 a 570 nm, las plantas que se desarrollaron en el túnel con cubierta de policarbonato rojo, fueron de mayor altura y desarrollo foliar, pero con menor rendimiento de frutos. El mayor rendimiento de frutos se obtuvo bajo la cubierta de policarbonato traslúcido y el polietileno difuso de alta densidad.

Many modern human activities rely greatly on plastic foams, whose consumption and production have considerably increased in the past decades. The use of plastic products has had positive impacts on human general welfare; however, the negative effects derived from their inappropriate disposition have become a major concern, especially during the current COVID-19 sanitary emergency, in which the utilization of single-use plastics has rapidly increased. Although some plastic polymers such as polyethylene (PE) and polystyrene (PS) can be recycled, the high demand for energy and technology, the use of potentially toxic substances and the low profitability of the process, make this option nonoptimal. In this situation, biological treatment of plastic waste is emerging as a promising alternative and the use of PE and PS-eating organisms, such as mealworms and waxworms, has attracted the attention of researchers around the world. The aim of this review is to synthesize the most recent advances in the field of plastics polymers degradation by insects larvae and an analysis of the current and future trends of this developing research area. [ABSTRACT FROM AUTHOR]

Análisis del comportamiento global en la era de las tecnologías, del ensimismamiento y de las reacciones precarias.

Polyethylene (PE) is considered one of the most versatile thermoplastics available today. However, it exhibits several limitations related to its low melting point, low heat resistance, tendency to crack propagation, and its low resistance to rupture under stress. In order to overcome these deficiencies, several processes for crosslinking PE chains were developed, which makes this material more stable to temperature changes. In this work, methods based on peroxide (PEX-A) and silane (PEX-B) as chemical modification agents for PE chain crosslinking were analyzed, aiming to apply PE in pipes for conduction water. The materials were characterized by infrared spectroscopy (FTIR), gel content, and thermal analysis (TGA and DSC) to achieve those objectives. Also, some mechanical properties such as tensile strength and hardness and the determination of the heat deflection temperature (HDT) were evaluated. Spectra demonstrated the presence of the functional groups characteristic of PE and the incorporation of siloxane groups in PEX-B. Gel content values obtained were above 60% and indicated the formation of crosslinked chains between the molecules of the polymers. The thermal analysis suggests a greater efficiency in forming a chain network by the silane crosslinking process compared to the peroxide process. As for the mechanical tests, they also showed improvement in the mechanical properties of the crosslinked polymer when compared to the respective original PE. Thus, the silane method provided sufficient results to conclude that the properties evaluated are superior compared to the peroxide crosslinking method. [ABSTRACT FROM AUTHOR]

Introduction: In primary hip replacement, different materials are used for bearing surfaces. In our medium metal or ceramic heads with highly crossed-linked polyethylene (PA) are the most used. These combinations have good results, but it is not clear which is clinically superior. The objective of this study is to determine whether there is any clinically significant difference based on a systematic review of the literature and national registries of arthroplasty. Material and methods: We conduct a systematic review of the literature and national registries of arthroplasty and we were looking for studies comparing bearing surfaces: ceramic-highly cross-linked polyethylene (CP) and metal-highly cross-linked polyethylene (MP); describing the revision rate according to the surface type with a minimum 10-year follow-up. The outcome evaluated was: review rate for any cause depending on surface type. Results: Two out of fifteen national registries were included. The Australian registry shows a difference in the 15-year revision rate: CP: 6.3 (IC 5.8, 6.7) vs MP: 5.1 (IC 4.6, 5.7). The New Zealand registry shows no differences in revision rate/100 components/year: CP 0.54 (0.48-0.61) vs MP 0.61 (0.57-0.66). We do not find clinical studies with inclusion criteria that answer the research question. Conclusion: The results of this review show a high survival rate with the use of highly cross-linked polyethylene, the results are similar when using ceramic or metal heads. [ABSTRACT FROM AUTHOR]

act High density polyethylene-clay, graphite or talc composites were produced using direct solvent in situ polymerization using a Ziegler catalyst system (TiCl4 and triethylaluminum in hexane). The produced polymer had a high average molecular weight and in inert atmosphere presents a thermal degradation above 400ºC. The thermal degradation of the polymers in the nanocomposites was shifted for higher temperature (until close to 500ºC) indicating an improvement in the thermal stability of the polymeric matrix. The inflammability tests clearly showed a retardation or attenuation effect of the flames progression for all nanocomposites due to the barrier effect for gases and volatile compounds. [ABSTRACT FROM AUTHOR]

Copyright of Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental is the property of Revista Eletronica em Gestao, Educacao e Tecnologia Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper reports the main results concerning the synthesis and characterization of methylsilane and octylsilane-modified silicas. The modification of the silicas with these groups aims to make the silica surface hydrophobic and thus compatible with high-density polyethylene (HDPE) in HDPE/silica composites. In the present work, two types of silica were organofunctionalized: a pyrogenic silica and a silica gel. The silicas were characterized by a series of complementary techniques with the objective of investigating the nature of the surface species and their textural and morphological characteristics. The SEM images showed that the modification of the silicas with organosilanes has been not resulted in changes on the morphology and on the size of silica particles. In relation to the texture properties, determined by N2 adsorption-desorption porosimetry, the silica modification resulted in a decrease of the specific area (SBET) and the mean pore volume, a behavior attributed to the partial coverage of the adsorption sites by the organosilane molecules. The TGA analysis showed that both the methylsilane groups and the octylsilane groups on the surface of silica and silica gel are thermally stable up to 200 ° C, which enables the organofunctionalized silicas in terms of thermal stability, for the process of preparing the composites by extrusion. The results of applying these organofunctionalized silicas in the development of HDPE/silica composites will be presented in a subsequent article, part II of this research. [ABSTRACT FROM AUTHOR]

In this work, the effect of silica particle size and organosilane type used in the silica organofunctionalization on the thermal and mechanical properties of high-density polyethylene (HDPE)/silica composites were evaluated. HDPE/silica composites were prepared by the extrusion method using two types of silica: fumed silica, with nanometric particle size and silica gel, micrometric, modified with organosilanes containing methyl or octyl functional groups. Silicas were added to the HDPE at 1% v/v concentration. The addition of the silicas to the HDPE did not influence the melt (Tm) and the crystallization (Tc) temperatures of the resulting composites but influenced its crystallinity. The mechanical property of Izod impact strength, the dynamic-mechanical rheological test (DMTA) and the surface contact angle analysis showed improvements in relation to pure HDPE when used methyl-modified pyrogenic silica as filler. This result suggests that the surface modification of pyrogenic silica with methylsilane groups results in a stronger interaction of this silica with the HDPE matrix. This effect was not observed for micron-sized silica gel, where modification with organosilanes was not sufficient to guarantee interfacial interaction with the HDPE matrix. [ABSTRACT FROM AUTHOR]

The roof color of tunnels and greenhouses can modify the spectral characteristics of solar radiation and affect the development and performance of plants. The objective in this study was to evaluate the effect of the color cover of a tunnel on the magnitude and characteristics of radiation on a sweet pepper culture (Capsicum annuum L.) and its relationship with chlorophyll content, growth and yield. This study was carried out in four tunnels covered with red, blue, and translucent polycarbonate and high-density diffuse polyethylene. The spectral properties of the radiation under each cover were determined with a spectroradiometer. The radiation effects on the growth and yield of plants were evaluated in a completely random design with sub-sampling in five treatments (covered tunnels and open field), three repetitions and three samples (plants) per replicate. The Tukey test (p≤0.05) was used for means comparison. The photosynthetically active radiation (PAR) transmitted under each cover during the crop’s growth cycle was of 79.22, 53.40, 49.52 and 23.35% for the translucent polycarbonate, high density diffused polyethylene, blue polycarbonate and red polycarbonate, respectively. The transmissivity wavelength ranging from 400 to 550 nm in the red polycarbonate was almost null. Therefore, plants under the red cover had a greater plant height and leaf area, but lower fruit yield. The highest fruit yield was under the high-density diffused polyethylene, due to its greater diffusivity and PAR penetration in the plants foliage. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to IUPAC, the composites are multicomponent materials comprising multiple, different (nongaseous) phase domains in which at least one type of phase domain is a continuous phase. High density polyethylene (HDPE) reinforced with silica particles is an example of a composite material. Diatomite is a natural silica commonly used in filter media. In the present work, the diatomite was organofunctionalized with methyltriethoxysilane (C1) and then used in the preparation of HDPE/diatomite composites with diatomite content of 2.0 and 5.0 wt%. The composites were evaluated in terms of mechanical properties by dynamicmechanical analysis (DMTA), Izod impact test and flexural strength and tensile strength tests. The Fourier transform infrared spectrum (FTIR) of the organofunctionalized diatomite presented bands characteristic of methyl groups, proving the efficiency of the surface modification. The addition of 5.0% diatomite in HDPE resulted in an increase of 8.0 °C in thermal stability, crystallinity (72 to 78%) and in approximately 4.0% in the storage modulus (G'), compared to pure HDPE.SEM analyzes showed the presence of diatomite agglomerates in the HDPE matrix. The Izod impact strength of the composites for this composite was 50 J / m, half of that observed for pure HDPE. The properties of tensile strength were not influenced by the presence of diatomite in HDPE. [ABSTRACT FROM AUTHOR]

Resumo A reciclagem mecânica é uma das possibilidades existentes para revalorização dos resíduos plásticos. Neste trabalho, foram acompanhadas as atividades de uma indústria, localizada em Teresina-PI, que realiza a reciclagem mecânica de polietileno (PEBD e PEAD) para a produção de sacolas. A qualidade da matéria-prima pós-uso influencia a qualidade do produto final e determina etapas adicionais em relação ao processamento da resina virgem, como lavagem, secagem e extrusão para produção de grãos. O efluente gerado na etapa de pré-tratamento dos reciclados, o consumo de energia e recursos humanos envolvidos impactam os aspectos ambientais, econômicos e sociais do processo. A reciclagem mecânica só pode ser considerada vantajosa se for dada uma destinação ou disposição final ambientalmente correta do que não é aproveitado na indústria; incorporada a externalidade econômica de realizar tratamento do efluente gerado, e, por fim, qualificar e remunerar de modo justo o catador que disponibiliza a matéria-prima para a indústria.

El presente trabajo comprende os aspectos más trascendentales del tratamiento de camas de cultivo con el uso del polietileno como acolchado en el cultivo del tomate, el cual es un aporte al ámbito del desarrollo sostenible medioambiental y agrícola, tiene como objetivo: Determinar el efecto de la cubierta de cama con polietileno en la producción de tomate orgánico (Solanum lycopersicum L.) variedad rio grande, bajo condiciones de Pucallpa. Los resultados mostraron que las camas con acolchado de polietileno es el mejor con 5,496.50 kilos más que el tratamiento sin cubierta de plástico. Los resultados permitieron concluir que hubo efecto positivo del tratamiento con cubierta de plástico que incremento los rendimientos en 40.35% en comparación al tratamiento sin cubierta de plástico o testigo, Se presentó menos ataque de plagas y enfermedades en el tratamiento con cubierta de plástico, pero no hubo diferencias estadísticas, para el número de frutos por planta tampoco se presentó diferencias significativas, pero hubo ligero incremento en el tratamiento del suelo protegido con cubierta de plástico, se nota ligeras diferencias para el tratamiento cubierta del suelo con plástico. Se sugirió: Repetir el experimento con otros cultivos de similar periodo vegetativo que el tomate y usar plástico de diferentes colores, así como repetir ensayos usando rastrojos de plantas.

The plastic bag used in the packaging of mozzarella cheese was characterized, for which the quality of the bag was evaluated through its identification by the method of solubility in organic and inorganic solvents, the quality of sealing by the colorful solution method, the determination of the speed of transmission to water vapor by the method gravimetric, dimensions and thickness. The results of the functional length and width presented average values of 396 mm and 374 mm respectively, the material proved to be made up of two flexible layers with a total thickness of 67.17 μm; an inner layer of polyethylene with a thickness of 47 μm and an outer layer of polyester with a thickness of 21 μm. The transmission speed to water vapor of the container was 2.33 g/m2d. [ABSTRACT FROM AUTHOR]

A process to obtain profiles from henequen (Agave fourcroydes Lem.) fiber reinforced high-density polyethylene (HDPE) matrix composite material by extrusion method is presented. Data on thermal stability and microstructural features of the henequen fibers used are presented. Behavior of material in process and its influence on mechanical properties are analyzed. A comparison between obtained material and another currently in production and incorporating wood particles from pine sawdust (Pinus sp.) as reinforcing element is exposed. Tensile strength of henequen fiber reinforced composites ranges from 12 to 15 MPa, slightly lower than the one obtained from wood particle reinforced composite material. Nevertheless, the impact strength and Young's modulus values double the ones obtained with pine's particles reinforcement. Characterization of both materials obtained and process, it allowed to both identify elements related to differences on tensile strength and propose processing alternatives to allow introducing henequen fibers. [ABSTRACT FROM AUTHOR]

As garrafas de Polietileno (PET) são largamente utilizadas no mundo, seja por facilidade de design, por durabilidade ou por facilidade de manuseio, transporte e estocagem. No entanto, problemas de logística reversa onde a embalagem em pós-uso, por não ter uma destinação final adequada, acarreta em poluição ao meio ambiente. Visando à retirada deste material do meio ambiente de forma ecologicamente responsável, associada à redução de custo de produção e de peso próprio de lajes nervuradas de concreto, este artigo vem a discutir pesquisa elaborada por meio de análise laboratorial e de viabilidade de construção de lajes com a utilização de garrafas PET em seu interior. Verificaram-se aspectos positivos, econômicos, técnicos e ambientais.