Efecto en las propiedades mecánicas de una resina pinífera modificada biodegradable, al utilizarla como compatibilizante o acoplante en formulaciones elastoméricas sin o con fibra de agave y hule de poli(estireno-butadieno). Un paso hacia la formulación

En este trabajo se valora la eficiencia de una resina de pino modificada biodegradable (A-30), al utilizarla como compatibilizante o acoplante para sustituir al resorcinol (que es tóxico y no es biodegradable), comparando las propiedades mecánicas (contra formulaciones preparadas usando el sistema resorcinol-hexametilentetramina (R-HMT) en: a) polímeros elastoméricos reticulados de estireno-butadieno (SBR), y: b) compósitos de SBR reforzados con fibra de agave de desecho. Para la comparación como compatibilizante, aquí se preparan formulaciones equivalentes con A-30 o R-HMT. Para la comparación de los compósitos equivalentes, se varía el agente de acoplamiento (R-HMT o A-30) y la cantidad de azufre como agente de entrecruzamiento (2,5 partes por cien de elastómero (phr), 7,5 phr o 15 phr). En las pruebas de tracción a temperatura ambiente, y el análisis mecanodinámico con barridos de temperatura (de - 70 °C a 40 °C) y frecuencia (de 0,4 Hz a 40 Hz), se obtuvieron incrementos en módulos (hasta un 74 % en módulo de Young) y en capacidad de deformación (hasta 260 %), para los materiales conteniendo el agente A-30, por encima de las formulaciones en las que se usó el resorcinol. El mejor desempeño como compatibilizante o acoplante del A-30, se reflejó también con claridad morfológicamente mediante microscopía electrónica de barrido, al mostrar mayor compacidad en la matriz formulada y mayor cercanía entre fibra y matriz en muestras fracturadas criogénicamente. Se ha demostrado aquí, que el A-30 puede sustituir al par R-HMT con éxito, ya que funciona mejor como agente compatibilizante o acoplante y es biodegradable. Este tipo de agentes tiene un gran potencial para contribuir al desarrollo de elastómeros y compósitos flexibles amigables con el medio ambiente

Creep and morphology comparison of gradient and IPN systems

Due to its performance, the importance of interpenetrating polymer networks (IPN's) has increased in recent years. If a composition gradient is included in the IPN, the expected gradient in properties expands the field of applications of multicomponent polymer systems. In this work, IPN's with and without gradient composition were prepared by photopolymerization using styrene and butyl acrylate as monomers one and two, respectively. Uniaxial creep measurements showed the superiority of the gradient material. SEM studies at different depths in the samples, allowed to observe domain sizes in the dispersed phase, and how the morphology gradient vary within a sample

Analysis of butyl acrylate diffusion in a polystyrene matrix in the gradient polymer formation region

The diffusion phenomena in the formation of gradient polymers is studied. The gradient polymers were made from polymer blends accomplished by sequential polymerization. A mass transfer model to predict the monomer sorption in a polymer matrix in the glassy region is presented. The diffusion coefficients were evaluated at different temperatures and compared with values obtained with Fick's equation. Another model takes into consideration to estimate surface concentration changes

Analysis of butyl acrylate diffusion in a polystyrene matrix in the gradient polymer formation region

The diffusion phenomena in the formation of gradient polymers is studied. The gradient polymers were made from polymer blends accomplished by sequential polymerization. A mass transfer model to predict the monomer sorption in a polymer matrix in the glassy region is presented. The diffusion coefficients were evaluated at different temperatures and compared with values obtained with Fick's equation. Another model takes into consideration to estimate surface concentration changes

Efecto en las propiedades mecánicas de una resina pinífera modificada biodegradable, al utilizarla como compatibilizante o acoplante en formulaciones elastoméricas sin o con fibra de agave y hule de poli(estireno-butadieno). Un paso hacia la formulación de elastómeros verdes

In this work, the effectiveness of a biodegradable modified pine rosin (Amberyl MP-30 (A-30)), is evaluated as compatibilizer or coupling agent to substituteresorcinol (which is toxic and non-biodegradable) in elastomeric formulations. Their mechanical properties are compared vs formulations containing resorcinol-hexamethylenetetramine (R-HMT) in: a) styrene–butadiene elastomers (SBRs), and: b) SBR composites reinforced with discarded agave fibers. For the comparison as compatibilizer, equivalent formulations containing resorcinol or A-30 are prepared. Likewise, for the equivalent composites comparison, the coupling agent (R-HMT or A-30) and sulfur amount as crosslinking agent (2,5 parts per 100 rubber (phr), 7,5 phr or 15 parts per 100 phr) are varied. The Tensile tests at room temperature, and the mechanodynamic analysis using sweeps of temperature (from - 70 °C to 40 °C) and frequency (from 0,4 Hz to 40 Hz), allowed the observation of moduli improvements (up to 74 % in Young modulus) and deformation capacity (up to 260 %) for the materials with A-30 over the materials where resorcinol was used. The better performance as compatibilizer or coupling agent of the A-30 was also shown with clarity in the morphological characterization, showing higher compacity in the formulated polymer matrix, and higher closeness between matrix and fibers, comparing with fractured samples using R-HMT. It has been shown here, that formulating rubbers or elastomeric composites with A-30 and HMT, can successfully substitute the R-HMT pair, because it works better as compatibilizer or coupling agent and is biodegradable. Agents of natural origin like this one, have a great potential to contribute to the development of elastomers and flexible composites that are environmentally friendlyEn este trabajo se valora la eficiencia de una resina de pino modificada biodegradable (A-30), al utilizarla como compatibilizante o acoplante para sustituir al resorcinol (que es tóxico y no es biodegradable), comparando las propiedades mecánicas (contra formulaciones preparadas usando el sistema resorcinol-hexametilentetramina (R-HMT) en: a) polímeros elastoméricos reticulados de estireno-butadieno (SBR), y: b) compósitos de SBR reforzados con fibra de agave de desecho. Para la comparación como compatibilizante, aquí se preparan formulaciones equivalentes con A-30 o R-HMT. Para la comparación de los compósitos equivalentes, se varía el agente de acoplamiento (R-HMT o A-30) y la cantidad de azufre como agente de entrecruzamiento (2,5 partes por cien de elastómero (phr), 7,5 phr o 15 phr). En las pruebas de tracción a temperatura ambiente, y el análisis mecanodinámico con barridos de temperatura (de - 70 °C a 40 °C) y frecuencia (de 0,4 Hz a 40 Hz), se obtuvieron incrementos en módulos (hasta un 74 % en módulo de Young) y en capacidad de deformación (hasta 260 %), para los materiales conteniendo el agente A-30, por encima de las formulaciones en las que se usó el resorcinol. El mejor desempeño como compatibilizante o acoplante del A-30, se reflejó también con claridad morfológicamente mediante microscopía electrónica de barrido, al mostrar mayor compacidad en la matriz formulada y mayor cercanía entre fibra y matriz en muestras fracturadas criogénicamente. Se ha demostrado aquí, que el A-30 puede sustituir al par R-HMT con éxito, ya que funciona mejor como agente compatibilizante o acoplante y es biodegradable. Este tipo de agentes tiene un gran potencial para contribuir al desarrollo de elastómeros y compósitos flexibles amigables con el medio ambient

Redox initiation in semicontinuous polymerization to search for specific mechanical properties of copolymers

In this work, for a semicontinuous emulsion polymerization reaction, it is shown that using a redox initiation system at 40°C, substantial modifications in copolymer chain composition with conversion can be easily obtained. To test controllable trajectories for comonomer feeding, linear and parabolic profiles were chosen to get different types of chain composition variations for the 50/50 w/w styrene/n-butyl acrylate system. For the "forced composition copolymers,"the molecular weight averages and distribution were obtained by size exclusion chromatography. The composition along conversion was followed by proton nuclear magnetic resonance to determine the weight composition distribution (WCD) of the copolymer chains. Mechanodynamic (dynamic-mechanical analysis),tensile, and hardness tests exhibited consistent results depending on the WCD that outcomes from the respective feeding profile. The results confirm that this methodology is of great potential for industrial applications when looking for synergy in copolymer properties, and low-cost processes.José Manuel Sandoval-Díaz thanks CONACyT for the scholarship during the Ph.D. program and Universidad de Guadalajara and Institute of Polymer Science and Technology, ICTP-CSIC, for the support to carry out part of the experimental research Luis Javier González-Ortiz for assistance in data analysis

Interrelationship between feeding profiles and chains composition-morphology-mechanical properties for forced composition copolymers synthesized by redox initiation

A semicontinuous emulsion copolymerization via redox initiation (tetramethylenediamine with potassium persulfate) is used to show how, by variations in the comonomers feeding profile, substantial modifications can be obtained in the composition of the copolymer chains that are formed along the reaction, which in turn modifies in a significant manner the morphology and mechanical properties of the materials. That is, changing the comonomers feeding profile and building a histogram for the composition distribution of the synthesized copolymer chains, changes in mechanical properties can be explained along with changes in morphology. Styrene and n-butyl acrylate 50/50 w/w were used to prepare the copolymers. To study the effect of the aforementioned changes caused by the feeding profiles, three pairs of feeding profiles were considered; the “A profiles” were selected to promote different composition histograms, whereas the “B profiles” represent modified “A profiles”. Global conversion was determined by gravimetry and the global copolymer composition along conversion by H NMR. Stress–strain tests and dynamic-mechanical analysis were performed to evaluate their mechanical properties. An equivalent statistical copolymer was the reference material. Using redox initiation, the results show for a semicontinuous process, that a fast reaction at low temperature is very convenient. In addition, the interrelation analysis for feeding profiles-histogram-morphology-mechanical properties performance, allows for the first time, the understanding of copolymers mechanical performance as a whole, which can be used as a basis to ease their tailored design.Francisco Javier Rivera Gálvez thanks CONA-CyT for the scholarship during the Ph.D. Program, and all authors thank the Universidad de Guadalajara and Institute of Polymer Science and Technology, ICTP-CSIC for the financial support to carry out the experimental research

Mechanothermal performance evaluation of a biodegradable resin as coupling agent for hydrophobic polymer/cellulosic composites

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 (tequilana Weber) 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 celulósicasIn 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 (tequilana Weber) 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 agent

A Methodology Towards Mechanical Properties Optimization of Three-Component Polymers by the Gradual Variation of Feed Composition in Semi-Continuous Emulsion-Free Radical Polymerization

© 2019 by the authors.In this work, a new methodology for the synthesis of three-component polymers (TCPs) was developed using a seeded, semi-continuous free-radical emulsion polymerization towards the optimization of the moduli–ultimate deformation performance and energy dissipation capacity for a styrene (S), n-butyl acrylate (BA), and 4-vinylbenzyl chloride (VBC) system. The three components were sequentially fed in pairs, varying feed composition along the conversion using S as the common monomer. To prepare a reference material, an industrial method was utilized with those monomers, using an equivalent global composition in a two-stage batch process (TS). Nanophase formation in the particles was observed by transmission electron microscopy (TEM), while the separation of the phases in the solid samples was observed by atomic force microscopy (AFM). The changes in glass transition temperature were determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The latter was primarily used to compare mechanodynamic properties as a function of temperature for the two synthesis methods used. Thus, the higher toughness of the forced composition three-component polymeric materials was evaluated by means of their energy dissipation capacity, toughness, and stress–strain measurements at several temperatures.The authors thank the Universidad de Guadalajara, CONACyT and ICTP for financial support and to MINECO’s support (project MAT2016-81138-R).Peer reviewe