The effect of interface debonding behaviors on the mechanical properties of microPCMs/epoxy composites

Abstract

Microcapsules containing phase change materials (microPCMs) can be filled in polymeric matrix forming smart temperature‐controlling composites. The aim of this study was to investigate the relationship between the interface behaviors and the mechanical properties of methanol‐melamine‐formaldehyde shell microPCMs containing paraffin/epoxy matrix composites. The typical microPCMs with core/shell ratio of 2/1 shapely decreased their average diameter from 26.0 ± 1.5 to 13.8 ± 3.4 μm with the increasing of stirring speed from 1,000 to 3,000 r min−1. But, both the thickness and yield point of shells had a little variation. Young's modulus of composites was almost independent on the particle size of microPCMs with lower volume fractions (5%–10%). For composites with higher microPCMs loading (20%–30%), there was a slight decrease in modulus with increasing particle size. The data of tensile strength decreased obviously with the increasing of the average diameter of microcapsules for composite samples with the same particle loading. A repeated heat‐transmission treatment was applied to enhance the interface debonding. The results show that the violent thermal transmission had decreased the mechanical properties of microPCMs/epoxy composites. The scanning electron microscopy morphologies had also proved that these phenomena attributed to the interphase separation and cracks. Moreover, a semiexperiential conclusion is that the increasing of interface area of composites will at the same time give more structure defects leading to poor mechanical properties. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Mechanical reinforcement of electrospun water-soluble polymer nanofibers using nanodiamonds

“…According to this model, b is taken to be 2/3 considering NDs are spherical fillers. Generally, the value of a below 1.21 represents good adhesion of filler to composite matrix . Therefore, to judge whether the adhesion of spherical fillers to matrix is good or bad, the critical value of σ composite can be deduced from Eq .…”

Thermotropic glazings for overheating protection. II. morphology and structure–property relationships

“…The CTE of PMMA and paraffin for example are in the range of 6–8 × 10 −5 and 0.7–1.1 × 10 −3 K −1 , respectively . The higher CTE of paraffin forced the embedded additive to contract more intense than the surrounding matrix PMMA upon cooling during manufacturing, thus yielding formation of vacuoles when implying limited adhesion at the interface matrix/additive . All of these layers displayed an increase in solar hemispheric and diffuse transmittance upon heating.…”

“…Vacuole formation was ascribed to processing effects: mixtures of UV‐curable resin and thermotropic additive were exposed to UV‐radiation yielding crosslinking reaction in the matrix and heating up of the mixture due to absorption . Upon cooling during manufacturing its higher CTE forced the embedded additive to contract more intensively than the surrounding matrix material, thus yielding formation of vacuoles when implying limited adhesion at the interface matrix/additive . Layers M4A1, M4A2, and M4A6 displayed an increase in solar hemispheric and diffuse transmittance upon exceeding the threshold temperature.…”

Application of the thermal energy storage concept to novel epoxy–short carbon fiber composites

“…Lightweight polymer matrix composites coupling structural or semistructural functions and TES capability could be successfully applied where weight and volume savings need to be combined with precise temperature control. Even though several papers have recently been published on encapsulated and shape‐stabilized PCMs in various polymer matrixes, only a few papers dealing with the development of structural composites with TES capability can be found. The major parts of the scientific reports deal with sandwich structures for thermal management with or without the introduction of a PCM.…”