Segmental dynamics of polyurea: Effect of stoichiometry

Fragiadakis, D.; Gamache, Raymond M.; Bogoslovov, R. B.; Roland, C. M.

doi:10.1016/j.polymer.2009.11.028

Cited by 131 publications

(95 citation statements)

References 27 publications

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“…Polyurea is readily synthesized from aromatic or aliphatic isocyanates with chemical functionality of oligomeric diamines [16], which could be easily mixed and sprayed onto the surface of a metal like steel. e plates had been prepared by grit blasting to remove the surface metal rust and then covered with an epoxy primer to enhance the adhesion between metal and polyurea.…”

Section: Test Platementioning

confidence: 99%

Experimental Investigation of Polyurea‐Coated Steel Plates at Underwater Explosive Loading

Dai

Wan

et al. 2018

Advances in Materials Science and Engineering

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To improve the survivability of ship structures at underwater explosion, thin steel plates coated with polyurea were used to investigate the blast protection effect. During the experimental tests of bare steel plates at different standoff, an appropriate distance was selected as the reference standoff to perform the tests of coated plates. Experimental tests of different coating locations (front versus back) and coating thickness were carried out to study the influencing factors of blast resistance for metal substrate plates. Compared with the bare steel plates, the polyurea coating was found to reduce the deformation of the test plates at blast tests in both cases of the front and back surface locations of the polyurea layer. An increase in the coating thickness also mitigates substantially the deformation of plates. In addition, the properties of the material and the substrate-coating bond strength may also affect the protective effect of the polyurea coating.

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Section: Test Platementioning

confidence: 99%

Experimental Investigation of Polyurea‐Coated Steel Plates at Underwater Explosive Loading

Dai

Wan

et al. 2018

Advances in Materials Science and Engineering

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“…On the basis of the behavior when changing stoichiometry, temperature, or pressure, we previously attributed the lower-frequency component (α′ process) to segmental relaxation of the soft phase in the interfacial regions between the soft and hard domains, while the primary, higher-frequency component was ascribed to segmental relaxation in the soft phase distant from interfaces. 3 With increasing water content the two components combine into a single α-peak. This process reflects the overall segmental dynamics of the soft phase (slightly plasticized compared to the dry polyurea) and the temperature for which τ α = 100 s roughly corresponds to the calorimetric glass transition temperature.…”

mentioning

confidence: 99%

Microstructure and Segmental Dynamics of Polyurea under Uniaxial Deformation

et al. 2012

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Polyureas, formed by the rapid reaction between isocyanates and diamines, are attractive for various applications due to their outstanding mechanical properties, which can be tuned by varying component chemistry, molecular weight, and stoichiometry. Polyureas synthesized from a modified methylene diphenyl diisocyanate (Isonate 143 L) and polytetramethylene oxide-di-p-aminobenzoate (Versalink P1000) are widely utilized and investigated for energy absorbing applications such as impact mitigation and ballistic protection. In order to develop a more complete understanding of their mechanical response, we explore the effect of uniaxial strain on the phase separated microstructure and molecular dynamics. We utilize wide-and small-angle X-ray scattering to investigate amorphous segment and hard domain orientation, and broadband dielectric spectroscopy for interrogation of the dynamics. Uniaxial deformation was found to significantly perturb the phase-separated microstructure and chain orientation and result in a considerable slowing down and broadening of the polyurea soft phase segmental relaxation.

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“…Las poliureas son materiales segmentados con una fase dura (isocianato) dentro de una matriz flexible y presenta alta dureza debido a la gran cantidad de puentes de hidrogeno intermoleculares [1] . La principal aplicación de la poliurea es para la microencapsulación en las áreas: farmacéutica, industria cosmética, alimentaria y agroquímica, para reducir la contaminación ambiental generada por los plaguicidas, ya que al encapsular los ingredientes activos de estos productos se puede controlar su liberación, aumentando así su eficacia y persistencia, y además, reduciendo las cantidades liberadas al ambiente [2] , papeles de copia sin carbón [3] , microcápsulas multicapa, que mejoran sus propiedades de resistencia mecánica [4,5] , microencapsulación de catalizadores para aplicaciones en síntesis química [6,7] , microencapsulación de fosfato de amonio como retardante a la llama en aplicaciones textiles [8] , recientemente la microencapsulacion de materiales de cambio de fase ha sido estudiada para aplicaciones en campos de energía térmica y aires acondicionados de edificios, materiales de aislamiento térmico, fibras térmicas adaptables, etc.…”

Section: Introductionunclassified

Síntesis de microcápsulas de poliurea a partir de aminas renovables, mediante doble emulsificación

Mazo

Ríos²,

Restrepo³

2011

Polímeros

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Resumen: En este trabajo se realizó la microencapsulación de un perfume comercial mediante una doble emulsificación, la coraza de poliurea fue sintetizada por la reacción de Lisina con dos diisocianatos comerciales, uno aromático y otro alifático. En la síntesis se evaluó el efecto que tiene la relación molar amina:diisocianato y el tipo de emulsificante. Se optimizó el tamaño de partícula utilizando un diseño factorial 3 2 y análisis de superficie de respuesta, las variables fueron: cantidad de alcohol polivinílico y la relación de fase dispersa a fase continua. Las microcápsulas se caracterizaron mediante: análisis de calorimetría diferencial de barrido (DSC), espectroscopía infrarroja (IR), microscopía electrónica de barrido (SEM) y tamaño medio de partícula. La doble emulsificación permite un mayor rendimiento de encapsulación del perfume, las micropartículas presentan un menor tamaño de partícula cuando: se emplea diisocianato aromático, un aumento de coloide protector (PVA) y una disminución de la fase dispersa. Palabras-claves: Microencapsulación, poliurea, lisina, poliglicerol poliricinoleato. Synthesis of Polyurea Microcapsules from Renewable Amines by Double EmulsificationAbstract: This paper reports on the microencapsulation of a commercial perfume by means of a double emulsification, where the polyurea shell was synthesized by the reaction of lysine with two commercial di-isocyanates (aromatic and aliphatic). In the synthesis the factors evaluated were the amine:di-isocyanate molar ratio and the type of emulsifier. The particle size was optimized using a 3 2 factorial design and response surface analysis, with the following variables: amount of polyvinyl alcohol and the relationship of the disperse phase to continuous phase. The microcapsules were characterized using differential scanning calorimetry analysis (DSC), infrared spectroscopy (IR), scanning electron microscopy (SEM) and mean particle size. The double emulsification allows for a greater yield in the encapsulation of perfume. Furthermore, the microparticles have a smaller particle size when the aromatic di-isocyanate was used, also leading to an increase in the protective colloid (polyvinyl alcohol (PVA)) and reduction of the disperse phase.

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Segmental dynamics of polyurea: Effect of stoichiometry

Cited by 131 publications

References 27 publications

Experimental Investigation of Polyurea‐Coated Steel Plates at Underwater Explosive Loading

Experimental Investigation of Polyurea‐Coated Steel Plates at Underwater Explosive Loading

Microstructure and Segmental Dynamics of Polyurea under Uniaxial Deformation

Síntesis de microcápsulas de poliurea a partir de aminas renovables, mediante doble emulsificación

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