Adhesivos tipo poliuretano obtenidos a partir de aceite de ricino y almidón químicamente modificados

Abstract

Resumen: El aceite de ricino se modificó por transesterificación con pentaeritritol. Paralelamente, se utilizó la reacción de glucosilación con glicerol para dividir el almidón en unidades monosacáridos. El glucósido obtenido reaccionó por transesterificación con el aceite modificado por transesterificación con pentaeritritol. Se determinó el índice de hidroxilo de los poliol-glucósidos en función del contenido de pentaeritritol y almidón utilizados en la síntesis. Se sintetizaron redes interpenetradas de polímero de manera simultánea (SINs) con diferentes relaciones en peso poliuretano/PMMA de 100/0, 90/10, 80/20, 70/30, 60/40 y 50/50. Para la síntesis de la red de poliuretano (PU) se utilizaron los poliol-glucósidos y diisocianato de isoforona (IPDI) o con una relación NCO/OH = 1 y para la síntesis de la red de polimetilmetacrilato (PMMA) se utilizó peróxido de benzoílo como agente iniciador y dimetacrilato de etilenglicol como agente entrecruzante. Los SINs se caracterizaron por sus propiedades fisicomecánicas como resistencia al ataque químico, dureza, resistencia a la tensión y elongación de ruptura. La estabilidad térmica de los SINs se determinó usando análisis termogravimétrico (TGA). La morfología de superficie se determinó usando microscopia electrónica de barrido (SEM) y mostró una morfología de dos fases para todos los SINs. Palabras-clave: Aceite de ricino, almidón, glucosilación, redes interpenetradas de polímero, polimetilmetacrilato (PMMA). Abstract: Castor oil was modified by transesterification with pentaerithritol. In a parallel step, starch was divided into monosaccharide units by glycosylation in order to obtain products with high hydroxyl content. The values of hydroxyl index were measured according to the content of pentaerithritol and starch used in the synthesis. Novel simultaneous interpenetrating polymer networks (SINs) of polyurethane (PU) and poly(methyl methacrylate) (PMMA) in different weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50 were prepared based on polyol-glucosides. The polyurethane network was created by reacting the poliol-glucosides with isophorone diisocyanate maintaining a molar ratio NCO/OH = 1. The PMMA network was synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as the crosslinker. The SINs were characterized in their mechanical properties, such as Shore A hardness, tensile strength and elongation at break. Thermal stability of SINs was measured using thermogravimetric analysis (TGA). Surface morphology measured using scanning electron microscope (SEM) showed two-phase morphology for all the SINs. SINs based on polyurethane from castor oil modified and poly(methyl methacrylate) show limited compatibility at low concentrations of PMMA, but are totally incompatible at higher concentrations of PMMA.

Lithium catalyst concentration influence on bio-polyols structure and polyurethane adhesives properties

“…For a quantitative analysis of curing kinetics, isocyanate consumption (% NCO) was calculated using equation (1) [28]: (1) where I Ref is the intensity of the reference band (2924 cm −1 assigned to ν-CH 2 asymmetric stretching), I NCO is the intensity of the isocyanate band (2263 cm -1 ), t cure is the current reaction time, and t 0 is the reaction time of the first measurement spectrum. The isocyanate consumption was plotted as a function of the curing time in Figure 4.…”

“…Polyurethane adhesives are widely used because of their formulation versatility, which makes possible to obtain materials with a large range of mechanical properties and adhesion to several types of substrates. Polyurethane properties can be changed by combining different raw materials, as well as by varying the ratio between the isocyanate and the polyol used on its formulation or synthesis [1,2].…”

Toward UV-Triggered Curing of Solvent-Free Polyurethane Adhesives Based on Castor Oil

“…Noteworthy in this context is that vegetable oils not only provide an integrative reactive component of bioadhesive formulations but also constitute the fluid medium for the polymerization processes that lead to the adhesive polymer network. Among the adhesives prepared from such natural resources, polyurethanes are among the most widely studied ones. ,− Besides, polyurethanes, based on vegetable oils, have been demonstrated to exhibit low ecotoxicity and high biodegradability …”

Características mecánicas y térmicas de un poliuretano elaborado a partir de aceite de higuerilla (ricinus communis) para la adhesión de elementos estructurales de guadua angustifoliakunth

“…Con el propósito de mejorar las características fisicoquímicas y la funcionalidad de los poliuretanos, algunos trabajos se han encaminado al reemplazo de materias primas tradicionales por otras de origen vegetal, que lleven a productos y procesos económicamente viables e introduzcan propiedades de biodegradabilidad [4,5]. En particular, la síntesis de elastómeros de poliuretano con aceite de higuerilla (Ricinus commnunis) permite obtener un amplio rango de propiedades físicas y mecánicas, dependiendo de los contenidos de aceite y de diisocianato reaccionante.…”