Climatic Aging of Aviation Polymer Composite Materials: II. Development of Methods for Studying the Early Stages of Agin
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NCED MATERIALS AND TECHNOLOGIES
Climatic Aging of Aviation Polymer Composite Materials: II. Development of Methods for Studying the Early Stages of Aging E. N. Kablova and V. O. Startseva, * a
All-Russia Research Institute of Aviation Materials, Moscow, 105005 Russia *e-mail: [email protected] Received July 8, 2019; revised July 8, 2019; accepted July 23, 2019
Abstract—The review systematizes the results of studying the early stages of climatic aging of polymer composite materials by the methods that are sensitive to destruction in the surface layer of samples. The surface relief height, the diffusion coefficient of moisture, and the glass transition temperature of epoxy binders are shown to be sensitive to the action of temperature, humidity, solar radiation and other environmental factors. Keywords: polymer composite material, climatic aging, strength, elastic modulus, surface relief, diffusion, destruction DOI: 10.1134/S0036029520100110
INTRODUCTION In the previous part of review [1], we considered the influence of the significant factors of various climatic zones on the deformation–strength parameters of polymer composite materials (PCMs) using the results of works published in the last 5–8 years. The dependence of the generalized index of aging on the conditions and time of exposure, the physicochemical transformations in PCMs, the temperature, the nature of a reinforcing filler, the presence of adsorbed moisture, and the methodological measurements errors was shown. Earlier studies were analyzed in [2–4]. The common property of aviation PCMs is a high stability of the mechanical properties even under extreme climatic conditions [5]. For example, the standard deformation–strength parameters are weakly sensitive to the physicochemical processes occurring in a material in the first years of full-scale exposure of PCMs: the ultimate tensile strength and the elastic limit measured during tension, compression, bending, and interlayer shear after various exposure times differ by several percent from the initial values, and their values fluctuate in a scatter band. To reliably estimate the change in the highly stable properties of PCMs under open climatic conditions for a relatively short observation time (1–3 years), it is necessary to increase the number of measurements significantly [6], which requires a larger number of expensive samples. Therefore, the research methods that are sensitive to the early stages of climatic aging of PCMs are important. It is of interest to reveal the indicators that change significantly at an insignificant change in the mechanical properties, and this change could be reliably measured using modern experimental equipment. Works in this
field are performed in the All-Russia Research Institute of Aviation Materials in terms of the strategic directions of designing materials and technologies of their processing until 2030 [7]. In this part of the review, we analyze the results of the studies performed at the Gelendzhik Climatic Testing Center (GCCI) of the All-Russia Research Institu
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