Damage Processes in Reinforced Reaction Injection Molded Polyurethanes

Abstract

The microdeformation and damage mechanisms in glass fiber reinforced reaction injection molded (RRIM) polyurethane composites have been studied. Two surface conditions represented the extremes in good and poor fiber-matrix adhesion. Deformation mechanisms observed directly by an SEM technique with the specimen deformed in three-point bend were correlated with the number and amplitude distribution of acoustic emission (AE) events detected during tensile testing. Yielding of the unreinforced resin was accompanied by microcracking initiated at holes that produced AE with a peak at 43 db. A similar AE pattern observed in the untreated fiber composites was also identified with microcracking at holes in the resin and at rod-shaped holes produced by debonded fibers. The amine-treated fiber composite exhibited considerably more AE activity in the yield and post-yield regions with additional peaks in the amplitude distribution at 59 db and 65 db. These were identified with microcracking at the well-bonded interface and fiber fracture respectively.

A Comparative Study on the Mechanical Properties of Different Natural Fiber Reinforced Free-Rise Polyurethane Foam Composites

“…These natural fibers provide a cost benefit compared to synthetic fibers, while also promoting the foam’s sustainable properties. Moreover, they consist of hydroxyl groups, which may form bonds with the −NCO group of isocyanates upon interaction during the foaming process . In addition to the integrity fillers provided to foam cells, interfacial interactions can help strengthen bonds between the fiber and PU, which give these natural fibers added compatibility with PU chains .…”

“…Moreover, they consist of hydroxyl groups, which may form bonds with the −NCO group of isocyanates upon interaction during the foaming process. 7 In addition to the integrity fillers provided to foam cells, interfacial interactions can help strengthen bonds between the fiber and PU, which give these natural fibers added compatibility with PU chains. 7 Alternatively, fillers such as hazelnut have hydrophobic properties, which can improve foam hydrolytic stability.…”

“…7 In addition to the integrity fillers provided to foam cells, interfacial interactions can help strengthen bonds between the fiber and PU, which give these natural fibers added compatibility with PU chains. 7 Alternatively, fillers such as hazelnut have hydrophobic properties, which can improve foam hydrolytic stability. Aside from the desired properties natural fillers possess, they are also easily accessible in the natural environment.…”

Utilization of Flax Fibers and Glass Fibers in a Bio-Based Resin

“…Owing to the versatility of polyurethane chemistry, a broad range of properties and applications are possible for reinforced composites, such as seat frames, sun shades, door panels, package trays and truck box panels. Adhesion between the polyurethane matrix and the fiber surface is also an important factor in the improvement of mechanical performances [6]. Petrochemical-based polyester, polyether, and acrylic polyols are the main types of polyols used in PUs, but interest in plant oil-based polyols is growing [1,2,7].…”

Configurational bias Monte Carlo simulation of phase segregation in block copolymer networks

“…Of special interest to the automotive industry are polyurethane-glass interactions. Several studies [1][2][3][4] have demonstrated that good adhesion at the interphase between the polyurethane and glass is essential to ensure overall structural integrity for various applications utilizing these composite materials. Agrawal and Drzal [5][6][7] synthesized polyurethanes from polycaprolactone-based triols and toluene diisocyanate, the so-called soft segment and hard segment regions, respectively, using Macosko's terminology 8 in reference to the low and high glass transition temperatures of the soft and hard segment domains.…”