{"id":15687,"date":"2024-09-18T09:07:57","date_gmt":"2024-09-18T07:07:57","guid":{"rendered":"https:\/\/dev.shimadzu-testing.com\/?p=15687"},"modified":"2025-02-05T11:33:23","modified_gmt":"2025-02-05T10:33:23","slug":"3-point-flexural-test-of-cellulose-nanofibersreinforced-plastics","status":"publish","type":"post","link":"https:\/\/shimadzu-testing.com\/en\/know-how\/bending-testing\/3-point-flexural-test-of-cellulose-nanofibersreinforced-plastics\/","title":{"rendered":"3-Point Flexural Test of Cellulose NanofibersReinforced Plastics"},"content":{"rendered":"\t\t
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Introduction<\/strong><\/h2>\n

Plastic foam is lightweight and has excellent thermal\ninsulating and shock-absorbing properties because the\ninterior of the material contains numerous voids. On the\nother hand, the strength of plastic foam is lower than that\nof non-foam materials, as the volume of plastics per unit\nvolume is smaller. Addition of fiber or other reinforcing\nmaterials is one technique for obtaining satisfactory\nstrength in materials in which foaming is used to impart\nlight weight and thermal insulating properties. Although\nglass fiber and carbon fiber are often used as reinforcing\nmaterials, research and development using cellulose\nnanofibers (hereinafter, CNF) as a plant-derived high\nperformance new material has progressed recently.\nCellulose, consisting mainly of substances such as plant\ncell walls and cotton, is the most common\ncarbohydrate on Earth and has long been used as a raw\nmaterial for paper and cotton fiber. Recently, CNF with\nhigher functionality realized by defibrating cellulose to\nthe nano level has attracted interest. As a plant-derived\nmaterial, CNF has a low environmental impact, and also\nhas a variety of desirable properties, including low\nlinear expansion, a gas barrier property, and\ntransparency. In comparison with ferrous materials,\nCNF weighs only 1\/5 as much but has a high specific\nstrength, being 5 times stronger than steel, and\nstrength equal or superior to that of the conventional\nmaterials can be realized compounding CNF with\nplastics and rubber. Therefore, CNF has attracted\ninterest as a new material following carbon fiber.\nThis article introduces a 3-point flexural test using a\ndeflection measuring device and test speed in\ncompliance with JIS K 7171, which is generally used in\nstrength evaluation of plastics, and compares the\ndifferences in flexural strength with\/without CNF and\nwith\/without foaming.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Specimens<\/strong><\/h2>\n

high density polyethylene (hereinafter, HDPE). Test specimens *1 were prepared by adding 5 % CNF to HDPE as the matrix plastic. To investigate differences in the internal condition, internal observation of the specimens was performed with an inspeXio SMX- 100CT microfocus X-ray CT system prior to the tests. Fig. 1 shows CT images of the specimens, in which voids appear as black areas. There is no large difference between the non-foamed plastic without CNF (\u2460) and the non-foamed CNF reinforced plastic ( \u2461). In the foamed plastics, it was found that finer voids existed in a uniformly dispersed condition in the CNF reinforced plastic (\u2463) than in the plastic without CNF. Thus, the possibility that CNF impedes the growth and coalescence of voids is conceivable. \n

\n*1 Specimens provided by Kyoto Municipal Institute of Industrial Technology and Culture, a Local Incorporated Administrative Agency.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Measuring System<\/strong><\/h2>\n

Fig. 2 shows the condition of the test, and Table 1\nshows the test conditions. After measuring flexural\nmodulus of elasticity, the test speed was changed in\norder to measure flexural strength efficiently. For\nprecise measurement of the deflection of the\nspecimens, the test was performed by using a\ndeflectometer in the displacement measurements.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Fig. 2 Condition of Test<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Table 1 Test Conditions<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Test Results<\/strong><\/h2>\n

Fig. 3 shows the test results. With the CNF reinforced\nplastics (\u2461, \u2463), brittle facture occurred, as can be seen\nby the sharp decrease in test force after achieving\nmaximum strength. The non-CNF plastics ( \u2460 , \u2462 )\ndisplayed ductile behavior, in which the test force\ndecreased gradually.\nTable 2 summarizes the test results for all specimens.\nThe flexural modulus of elasticity was calculated from\nthe slope of flexural strain of 0.05 % to 0.25 %.\nComparing the values of the non-CNF HDPE (\u2460, \u2462)\nand the CNF reinforced plastic ( \u2461 , \u2463 ), the CNF\nreinforced plastic showed higher values for both the\nflexural modulus of elasticity and flexural strength.\nMoreover, comparing the coefficients of variation of\nthe flexural strengths of the HDPE plastic foam (\u2462) and\nthe CNF reinforced plastic foam (\u2463), it was found that\nvariation of the CNF reinforced plastic was smaller.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Fig. 3 Test Results<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Table 2 Summary of Test Results (Average of n=3)<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Conclusion<\/h2>\n