Valoración mecanotérmica de una resina biodegradable como agente de acoplamiento de materiales compuestos celulósicos/polímero hidrofóbico

En la búsqueda de plásticos reforzados con fibras que sean más amigables con el medio ambiente, aquí se presenta el primer estudio que evalúa la posibilidad de utilizar la brea natural de pino (en forma pura o maleinizada) como agente de acoplamiento (biodegradable). Polipropileno (matriz) y fibra de agave (Agave tequilana) de desecho a diferentes concentraciones (agente de refuerzo), fueron acoplados con cada uno de los agentes utilizados; su efecto en las propiedades mecánicas se comparó con el de un agente comercial de polipropileno modificado (Epolene E-43). Igualmente se prepararon, materiales compuestos sin agente de acoplamiento como referencia genérica. El desempeño mecanodinámico y mecanoestático de los materiales muestra claramente el incremento de propiedades mecánicas con los 3 agentes utilizados. La brea maleinizada mostró similitud o ligera superioridad sobre el agente comercial en el efecto logrado. La afectación en cristalinidad por la presencia de la fibra y el agente de acoplamiento correspondiente, fue evaluada mediante calorimetría diferencial de barrido. La absorción de agua como función del tiempo, permitió medir de forma indirecta el cambio logrado en la superficie de los materiales, y un análisis de FTIR, la valoración de la interacción fibra-polímero obtenida con el agente de acoplamiento. Tal interacción lograda con los agentes de acoplamiento, pudo ser además apreciada utilizando microscopía electrónica de barrido. Los resultados alcanzados marcan el camino para poder usar resinas naturales biodegradables como agentes de acoplamiento en el área de plásticos reforzados con fibras celulósicas. AbstractIn the search of useful environmentally friendly fiber reinforced plastics, this is the first study that evaluates the capability to use natural pine rosin (in pure or maleated glycerol ester form) as a biodegradable coupling agent. Polypropylene as polymer matrix and discarded agave fiber (Agave tequilana) as reinforcing agent at different concentrations, were coupled with each one of the two rosins above mentioned; a commercial maleated polypropylene (Epolene, E-43) agent was used to compare their effect. As generic reference, composites without coupling agent were also tested. Mechanodynamic and mechanostatic tests clearly show an increment in mechanical properties of the composites, using any of the 3 coupling agents. The results obtained with maleated rosin were similar or slightly better than the ones obtained with the commercial agent for composites with high fiber content. Fiber content and coupling agent effect on composites crystallinity, was evaluated by differential scanning calorimetry. In addition, water absorption as a function of time was followed to evaluate the effect of surface modification, and FTIR analysis allowed the observation of the fiber-polymer matrix interaction that was promoted with the coupling agents. The effect of such interaction obtained with the different coupling agents, was observed by scanning electron microscopy. The results show the feasibility to use the natural pine rosin in pure or modified form as biodegradable coupling agents

Effect of particle size on mechanical properties of core shell polymers prepared by microemulsion polymerization

The influence of particle size on the mechanical properties of core-shell polymers of polystyrene/poly(butyl acrylate) and poly(butyl acrylate)/ polystyrene made by a two-stage microemulsion polymerization process is reported here. In the first stage the polymerization was carried out in microemulsions containing no salt or an inorganic or organic salt to modify particle size. Smaller particles were obtained in the first stage when salts were used. The mechanical properties depend on core-shell particle size, composition and location of the parent polymers

Effect of morphology and particle size on the mechanical properties of SAN composites

The effect of morphology (core-shell and three-layer) and particle size on the mechanical properties of a SAN composite was investigated. The-core-shell (CS) and three-layer (TL) particles with same global composition (60PBA/40PS) were both obtained by emulsion and microemulsion polymerization to obtain particles with different size. The composites with particles obtained by emulsion, independently of the morphology (CS or TL) and particle size (170 and 220 nm); have at maxima in impact resistance at a 20% of particles content. A different behaviour, however, was observed when particles obtained by microemulsion were used. The composites with TC particles obtained by microemulsion polymerization show a maximum in impact resistance at 10% particles, but impact resistance of composites with CS particles obtained by microemulsion polymerization did not show a maximum and increases with particles content

Effect of particle size on mechanical properties of core shell polymers prepared by microemulsion polymerization

The influence of particle size on the mechanical properties of core-shell polymers of polystyrene/poly(butyl acrylate) and poly(butyl acrylate)/ polystyrene made by a two-stage microemulsion polymerization process is reported here. In the first stage the polymerization was carried out in microemulsions containing no salt or an inorganic or organic salt to modify particle size. Smaller particles were obtained in the first stage when salts were used. The mechanical properties depend on core-shell particle size, composition and location of the parent polymers

La tutela del soggetto in caso di anomalie o malformazioni genetiche: autodeterminazione e salute nelle scelte procreative

The effects of concentration and size of polyacrylamide (PAM) nanoparticles on the swelling behavior and compression modulus of nanostructured polyacrylamide hydrogels are examined here. These hydrogels are made by free radical polymerization in an aqueous solution of acrylamide and a crosslinking agent containing dispersed crosslinked PAM nanoparticles of different sizes, previously made by inverse emulsion or microemulsion polymerization. Faster swelling rate and larger equilibrium swelling are observed as particle content increases or the nanoparticle size diminishes. The compression modulus depends on the concentration and size of the disperse nanoparticles: it is larger for hydrogels containing smaller particles at similar concentrations, and it increases as the nanoparticle concentration augments. Moreover, the nanostructured hydrogels have larger compression modulus than those of the conventional ones having similar swelling. © 2015 Taylor & Francis Group, LLC

High-content polystyrene latex by microemulsion polymerization

The semicontinuous addition of styrene to a low solid-content (6 wt%) polystyrene latex obtained by polymerization of a three-component microemulsion, allows the production of a high solid-content latex (ca. 40 wt%) containing small particles (< 40 nm) of high molecular weight (> 106 g/mol). The method can be extended to latex made from microemulsions containing other water-insoluble monomers

High-content polystyrene latex by microemulsion polymerization

The semicontinuous addition of styrene to a low solid-content (6 wt%) polystyrene latex obtained by polymerization of a three-component microemulsion, allows the production of a high solid-content latex (ca. 40 wt%) containing small particles ( 106 g/mol). The method can be extended to latex made from microemulsions containing other water-insoluble monomers

Effect of morphology and particle size on the mechanical properties of SAN composites

The effect of morphology (core-shell and three-layer) and particle size on the mechanical properties of a SAN composite was investigated. The-core-shell (CS) and three-layer (TL) particles with same global composition (60PBA/40PS) were both obtained by emulsion and microemulsion polymerization to obtain particles with different size. The composites with particles obtained by emulsion, independently of the morphology (CS or TL) and particle size (170 and 220 nm); have at maxima in impact resistance at a 20% of particles content. A different behaviour, however, was observed when particles obtained by microemulsion were used. The composites with TC particles obtained by microemulsion polymerization show a maximum in impact resistance at 10% particles, but impact resistance of composites with CS particles obtained by microemulsion polymerization did not show a maximum and increases with particles content

High-Yield Synthesis of Silver Nanoparticles by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

CONACyT [SEP 2003-CO2-45436