3-Point Flexural Test of Cellulose Nanofibers Reinforced Plastics

Introduction

Plastic foam is lightweight and has excellent thermal insulating and shock-absorbing properties because the interior of the material contains numerous voids. On the other hand, the strength of plastic foam is lower than that of non-foam materials, as the volume of plastics per unit volume is smaller. Addition of fiber or other reinforcing materials is one technique for obtaining satisfactory strength in materials in which foaming is used to impart light weight and thermal insulating properties. Although glass fiber and carbon fiber are often used as reinforcing materials, research and development using cellulose nanofibers (hereinafter, CNF) as a plant-derived high performance new material has progressed recently. Cellulose, consisting mainly of substances such as plant cell walls and cotton, is the most common carbohydrate on Earth and has long been used as a raw material for paper and cotton fiber. Recently, CNF with higher functionality realized by defibrating cellulose to the nano level has attracted interest. As a plant-derived material, CNF has a low environmental impact, and also has a variety of desirable properties, including low linear expansion, a gas barrier property, and transparency. In comparison with ferrous materials, CNF weighs only 1/5 as much but has a high specific strength, being 5 times stronger than steel, and strength equal or superior to that of the conventional materials can be realized compounding CNF with plastics and rubber. Therefore, CNF has attracted interest as a new material following carbon fiber. This article introduces a 3-point flexural test using a deflection measuring device and test speed in compliance with JIS K 7171, which is generally used in strength evaluation of plastics, and compares the differences in flexural strength with/without CNF and with/without foaming.

February 21, 2019 GMT