A review on critical aspects of thermal shocks and thermal cycles in fiber reinforced polymer composites

Abstract

Fiber reinforced polymer composites (FRPCs) have gained great progress in a wide range of applications from construction and building structures to automobile and vehicle systems. During the operational lifetime, some FRPCs are exposed to various environmental conditions such as thermal cycles and thermal shocks. Fluctuation of the ambient temperature in the forms of thermal shocks or thermal cycles is one of the most important factors that deteriorate the durability and performance of the FRPCs. Compared to ceramic composites, less attention has been paid to the effects of thermal shocks and thermal cycles on the physical/mechanical properties of FRPCs. A comprehensive insight for the future advancements in this field is essential to possibly reduce the failure risks of FRPCs under thermal shocks and thermal cycles. The present work provides a comprehensive review on the physical/mechanical behavior of FRPCs under thermal cycles and thermal shocks. This work also provides a broad review on several factors that determines mechanical behavior of FRPCs, such as polymeric matrix, fiber type, incorporated nanofillers and fiber/polymer interface. Recent studies denoting important aspects and possible problems in mechanical performance of FRPCs under thermal shocks are also summarized.

Thermal Weathering of 3D-Printed Lunar Regolith Simulant Composites

“…Due to a difference in coefficients of thermal expansion (CTE) between the particles and the binder, the porosity of the prints is expected to increase with thermal cycling. The mechanism behind this is deadhesion between the binder and the particles, as the binder is more prone to expansion and contraction during heating and cooling cycles, respectively. ,, However, both the high content of solid particles and the differences in binder formulations make it challenging to determine to what extent the porosity might increase with thermal cycling. Therefore, the porosity of segments of printed dogbones was assessed via Otsu’s method of thresholding and is shown qualitatively and quantitatively in Figure a,b.…”

“…14 On the other hand, during cooling cycles below 0 °C, the main concern for composite materials is the contraction of the binder leading to delamination between layers and deadhesion between the binder and the particles. 25,30 This is a phenomenon that has been observed for carbon fiber-reinforced composites, where it results in the formation of microcracks that weaken the structural integrity of the materials and decreases the strength of parts. 30,32 These microcracks can also accelerate oxidative degradation of the binder, showing how the combined effect of cold and hot cycles can severely deteriorate composite parts.…”

“…25,30 This is a phenomenon that has been observed for carbon fiber-reinforced composites, where it results in the formation of microcracks that weaken the structural integrity of the materials and decreases the strength of parts. 30,32 These microcracks can also accelerate oxidative degradation of the binder, showing how the combined effect of cold and hot cycles can severely deteriorate composite parts. 29 The examples listed here highlight the importance of evaluating the thermal aging characteristics of any binder selected for lunar regolith formulations.…”

“…Mechanisms such as chain scission, and subsequent cross-linking have been demonstrated for fiberreinforced composites with thermoset epoxy-based binders. 30 Continued polymerization was observed for ultraviolet (UV) curable resins used in glass composites. 31 For thermoplastic polymer binders, the ratio of crystalline to amorphous regions is a driving factor for resistance to thermal cycling, as was shown for a polyethylene/Mars regolith material.…”

“…Fortunately, the performance of composites exposed to thermal cycling has been extensively studied. − During long heating periods, polymer binders are susceptible to degradation, particularly in the presence of oxygen. Mechanisms such as chain scission, and subsequent cross-linking have been demonstrated for fiber-reinforced composites with thermoset epoxy-based binders . Continued polymerization was observed for ultraviolet (UV) curable resins used in glass composites .…”