Ferdinánd Milán, Várdai Róbert, Móczó János, Pukánszky Béla
Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, P.O. Box 286, H-1519 Budapest, Hungary.
Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest, Hungary.
Polymers (Basel). 2021 Nov 14;13(22):3931. doi: 10.3390/polym13223931.
Acoustic emission, the detection of signals during deformation, is a frequently used method for the study of local deformation processes occurring in heterogeneous polymer systems. Most of these processes result in the evolution of elastic waves which can be detected by appropriate sensors. The analysis of several parameters characterizing the waves offers valuable information about the possible deformation mechanism. The acoustic emission testing of composites may yield very different number of signals from a few hundred to more than 100,000. This latter was proved to be affected mainly by particle size, interfacial adhesion and composition, but other factors, such as matrix modulus and specimen size, also influence it. Local deformation processes are claimed to have a strong effect on macroscopic properties. Indeed, a close correlation was found between the initiation stress of the dominating particle related process derived from acoustic emission testing and the tensile strength in both polypropylene (PP) and poly(lactic acid) (PLA) composites. However, in polyamide (PA)-based heterogeneous polymer systems, deformations related to the matrix dominated composite properties. Besides forecasting failure, the method makes possible the determination of the inherent strength of lignocellulosic fibers being around 40 MPa as well as the quantitative estimation of adhesion strength for composites in which interactions are created by mechanisms other than secondary forces. The proposed approach based on acoustic emission testing proved that in PP/CaCO composites, the strength of adhesion can be increased by ten times from about 100 mJ/m to almost 1000 mJ/m in the presence of a functionalized polymer.
声发射，即在变形过程中对信号进行检测，是研究非均质聚合物体系中局部变形过程常用的方法。这些过程大多会产生弹性波，可由适当的传感器检测到。对表征这些波的几个参数进行分析，可提供有关可能的变形机制的有价值信息。复合材料的声发射测试可能会产生数量差异很大的信号，从几百个到超过100,000个不等。事实证明，后者主要受粒径、界面粘附力和组成的影响，但其他因素，如基体模量和试样尺寸，也会对其产生影响。局部变形过程据称对宏观性能有很大影响。实际上，在聚丙烯（PP）和聚乳酸（PLA）复合材料中，从声发射测试得出的主要颗粒相关过程的起始应力与拉伸强度之间发现了密切的相关性。然而，在聚酰胺（PA）基非均质聚合物体系中，变形与基体主导的复合材料性能有关。除了预测失效外，该方法还能够确定木质纤维素纤维的固有强度约为40 MPa，以及对通过除二次力以外的机制产生相互作用的复合材料的粘附强度进行定量估计。基于声发射测试提出的方法证明，在PP/CaCO复合材料中，在存在功能化聚合物的情况下，粘附强度可从约100 mJ/m提高到近1000 mJ/m，提高十倍。
