Yañez María Julia, Barbosa Silvia Elena
Centro Regional de Investigaciones Básicas y Aplicadas Bahía Blanca, Argentina.
Microsc Res Tech. 2003 Aug 1;61(5):463-8. doi: 10.1002/jemt.10309.
Scanning electron microscopy (SEM) images of polymer blends followed by digital image analysis is a rapid and easy method for the measurement of particle size and dispersion. The particle size determination is done with appropriate off-line image analysis software. However, it is necessary to understand how machine parameters involved in the formation of the SEM image influence area measurements of morphological features. In this work, the influence of the accelerating voltage used during image acquisition was examined with standard samples and with polymer blend samples. A systematic study centered on two mutually exclusive assumptions of area variation or no area variation with accelerating voltage was carried out. The off-line image analysis software was then calibrated according to the assumptions. The main conclusion of this study was that kV has an important influence on area measurement in SEM images. This effect was observed for different standard materials (metallic and polymeric) and for the range of magnifications used. The higher the accelerating voltages, the greater the error at high magnification for polymer samples. As the beam energy increases, the primary electrons penetrate more deeply into the solid specimen, producing low-resolution signals. These signals degrade the image and surface details, which became less well defined. Therefore, images of polymer samples must be taken at lower accelerating voltages so the desired surface details can be imaged clearly. To avoid area measurement errors, particle measurement must be done with the calibration of the off-line image analysis software corresponding to the accelerating voltage and magnification used for the acquired images.
聚合物共混物的扫描电子显微镜（SEM）图像结合数字图像分析是一种快速简便的测量粒径和分散度的方法。粒径测定通过适当的离线图像分析软件完成。然而，有必要了解SEM图像形成过程中涉及的机器参数如何影响形态特征的面积测量。在这项工作中，使用标准样品和聚合物共混物样品研究了图像采集过程中使用的加速电压的影响。围绕加速电压下面积变化或无面积变化这两个相互排斥的假设进行了系统研究。然后根据这些假设对离线图像分析软件进行校准。这项研究的主要结论是，千伏对SEM图像中的面积测量有重要影响。在不同的标准材料（金属和聚合物）以及所用的放大倍数范围内都观察到了这种效应。对于聚合物样品，加速电压越高，高放大倍数下的误差就越大。随着束流能量增加，一次电子更深地穿透固体样品，产生低分辨率信号。这些信号会降低图像和表面细节的清晰度，使其变得不那么清晰。因此，聚合物样品的图像必须在较低加速电压下拍摄，以便清晰地成像所需的表面细节。为避免面积测量误差，必须使用与采集图像所用的加速电压和放大倍数对应的离线图像分析软件校准进行颗粒测量。
