Elucidation of mechanism for improving joining strength and durability of hybrid CFRTP by addition of nanofibers

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14060
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18020:Manufacturing and production engineering-related
• Research Institution: Fukuoka University (2022-2023); Kanagawa University (2021)
• Principal Investigator: Matsumoto Koki 福岡大学, 工学部, 助教 (50850070)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 射出オーバーモールド成形 / 炭素繊維強化熱可塑性樹脂 / 接合強度 / カーボンナノチューブ / 伝熱 / 結晶化度

Outline of Final Research Achievements

The joining strength of carbon fiber-reinforced thermoplastic (CFRTP) strongly depends on the interface temperature and pressure during the injection overmolding process. We attempted to strengthen the weld line by inserting the carbon nanotube (CNT)-reinforced polypropylene (PP) film at the interface. The objective of this research is to reveal the reinforcement effect of nanofiller against the joining strength.
We discussed the influence of CNT contents and the cooling rate of molding CFRTP substrate on the melting behavior of PP. The water-quench during the cooling of the heat-pressed substrate enables the reduction of the crystallinity of PP. Consequently, the joining strength was significantly improved. However, the effect of CNT addition on the joining strength was independent of the cooling rate. Thus, we revealed that the crystallinity reduction of PP at the surface of the substrate did not contribute to an increase in the joining strength by CNT addition.

Free Research Field

プラスチック成形加工

Academic Significance and Societal Importance of the Research Achievements

これまで射出オーバーモールド成形の接合強度の発現には，圧力や温度等のパラメーターを中心に考察が進められてきた．本研究は新たに接合部の樹脂の結晶化度に着目し，結晶化度の低下が接合強度の向上に大きく寄与できる事を示した．また，結晶化度に寄らずCNTの接合部の補強効果が得られる事が示された．本研究成果を踏まえ，射出オーバーモールド成形において，接合界面部にナノ繊維を配置することで信頼性の高い接合強度の発現が可能となる．これらの成形部材はモビリティの軽量化が可能となり，二酸化炭素の排出量削減等に大きく貢献できる．