In situ monitoring of porosity in liquid forming of composite materials: a new detection method based on effective dielectric constant

Research background and core methods: During the liquid forming (LCM) process of composite materials, resin infiltration into fiber preforms can easily introduce pore defects, which directly affect the mechanical properties and long-term durability of the product. The study “In situ monitoring the porosity of compounds in liquid composite molding based on the effective permission” was published in Volume 163 of Polymer Testing (October 2026) by Cheng Zhang、Fengjia Zhang、Haokun Lin、Peixian Lin、Jiayi Liu、Helezi Zhou、Huamin Zhou， Propose to use effective dielectric constant as a monitoring parameter for in-situ characterization of porosity during the molding process. The core idea of this study is to establish a correspondence between the effective dielectric constant and the porosity of composite materials, so as to reflect the evolution of pore content through changes in dielectric signals without damaging the product. Compared to traditional offline slicing or microscopic observation methods, in-situ monitoring can obtain real-time information during the molding process, providing a basis for adjusting process parameters.

Significance for the polymer additive industry

From the perspective of polymer aging and stabilization technology, the value of this work is mainly reflected in the detection and characterization level.

. Pores are the weak links in composite materials, and water and oxygen can easily penetrate through the pore channels, accelerating the hydrolysis and oxidative degradation of the matrix. The higher the porosity, the more difficult it is to ensure the weather stability of the material. Therefore, controlling the porosity at a lower level during the molding stage is the fundamental step in improving the long-term stability of the product. The in-situ dielectric monitoring method provides a new technical means for evaluating processing quality and creates conditions for subsequent research on the relationship between pore defects and degradation behavior. In the design of antioxidant and photostability systems, researchers need to consider the defect distribution in actual products, rather than relying solely on accelerated aging data of ideal defect free samples. This study suggests that defect characterization during processing should be combined with formula stability evaluation. In addition, the dielectric response itself is sensitive to changes in the internal structure of the material, and this idea has potential relevance to the study of the dispersion state and migration behavior of additives such as HALS and UVA in the matrix. The distribution uniformity of the composite system in the matrix will affect the local dielectric properties. In the future, such in-situ monitoring methods may be used to explore the corresponding relationship between the distribution of additives and material properties. Of course, this direction still requires specialized experimental verification, as the study itself did not involve auxiliary systems.

Objective understanding and limitations

It should be pointed out that this study focuses on porosity monitoring in liquid forming processes, and does not directly discuss polymer aging mechanisms, antioxidant systems, or the effectiveness of light stabilizers.

. Its significance lies in providing methodological references for material detection and characterization, rather than providing stability formula conclusions. Readers should distinguish the applicable boundaries of methods when citing, and avoid directly equating porosity monitoring results with weather resistance performance evaluation. Overall, this study demonstrates the potential application of dielectric parameters in online detection of composite material processing, and has reference value for improving the characterization system of polymer materials from processing to service.

Information source:In-situ monitoring the porosity of composites in liquid composite molding based on the effective permittivity， Organized by Herun Chemical.