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Our Filler Dispersion Evaluation Techniques

The characteristics of particle-dispersed composites depend greatly on the filler dispersion states (dispersed particle size distributions) in the matrix.
Therefore, in order to design a composite material with the desired characteristics,
it is important to measure the dispersed particle size distribution in base materials such as resin.

Dispersed Particle Size Distribution of Filler in Matrix


The Shiraishi Group developed the following three unique methods as technology for evaluating the dispersed particle size distribution in matrix.

Based on these evaluation techniques, the Shiraishi Group proposes the manufacturing and usage methods for filler powder that achieves the desired material properties.

1. Laser Diffraction Scattering Method

Nano Particle Size Distribution Analyzer SALD-7500nano (manufactured by Shimadzu Corporation)

When a particle is irradiated with a laser, diffracted or scattered light is emitted in various directions depending on the size of the particle. By detecting and analyzing this light, the particle size distribution is measured.
This method is capable of measurement from several nanometers to several hundred micrometers. Any type of base material can be measured by changing the solvent of the wet measurement system.

Measurement Example

First, we prepared plasticizer (DINP) dispersions containing various surface-treated calcium carbonates. The figure shows the dispersed particle size distributions in the matrix measured by the laser diffraction scattering method. We can quantitatively evaluate filler dispersions in the matrix from primary particles (about 100 nm) to aggregates of 100 μm or more.

2. Microscopy Method

Observation with an optical microscope is effective for measuring relatively large particle sizes from several tens of μm to several hundreds of μm.
Direct observation makes it possible to obtain rich visual information that cannot be expressed numerically. This makes the microscopy method of measurement highly reliable.

Measurement Example 1

A urethane sealant containing surface-treated calcium carbonate was sampled at each kneading time, and the dispersion state was measured by microscopy.
It is possible to quantitatively evaluate the progress of dispersion as the kneading time increases.

Measurement Example 2

We prepared a urethane sealant containing calcium carbonate with variable surface treatment and used microscopy to measure the dispersion state. We confirmed that greater amounts of surface treatment resulted in better initial dispersion and higher final dispersibility.
We also found that the elongation characteristics of the sealing material improved as the dispersion progressed. Furthermore, we were able to clarify the relationship between the dispersion states and the material characteristics.

External Presentations

Mika Moriyama, Kanehiro Osakabe, Masahiko Tajika, Jusuke Hidaka
Evaluating the Dispersibility of Calcium Carbonate in Sealing Material
The 56th Annual Meeting of the Adhesion Society of Japan

3. Dielectric Constant Measurement Method

When a filler is mixed with base material, the dielectric constant of the composite material changes depending on the dispersion state of the filler. Focusing on this relationship, we have developed a system that estimates the dispersed particle size distribution of fillers by measuring the dielectric constant of composite materials.

Measurement example

We changed dispersion states of calcium carbonate in a urethane sealant by changing the kneading time. Then, we measured the dielectric constant of the sealant.
The kneading time was long and dispersion progressed, thus causing the dielectric constant of the sealing material to increase. There was good alignment between the estimated and measured values.
In this way, the dispersion particle size distribution can be measured by measuring the dielectric constant.

External Presentations

Kizuku Kushimoto (Institute of Multidisciplinary Research for Advanced Materials, Tohoku University), Mika Moriyama, Jusuke Hidaka, and four others.
Measurement Method for Dispersion States of Filler Particles in Particulate Composite Materials by Macroscopic Permittivity
J. Soc. Powder Technol., Japan, 56, 4–14 (2019).

We fully utilize these new filler analysis techniques to accurately grasp customer requirements and deliver high-quality products/merchandise which satisfy customer requirements.