Thermomechanical and Thermo-hydro-mechanical Treatments of Luffa Cylindrical Fibers

ABSTRACT

The thermomechanical and thermo-hydro-mechanical treatments in Luffa cylindrical fibers were evaluated. The treatments comprised the hot pressing of the fibers in the dry condition (thermomechanical) and in the saturated condition (thermo-hydro-mechanical) with the objectives of porosity reduction and increase of modulus of elasticity of the fibrous material. The thermomechanical treatments were performed at 25, 120, 160 and 200°C. Tensile strength, moisture absorption, scanning electron microscopy (SEM), X-ray diffraction and thermogravimetric analysis were carried out to follow the effect of the proposed treatment. After treatment, the fibers presented a higher modulus of elasticity and lower moisture absorption. The best results were achieved for the saturated fibers pressed at 160ºC, as they presented a 95% increase in the modulus of elasticity and a 22% decrease in the moisture absorption in relation to the compressed fiber at room temperature. When exposed to heat and humidity, the densified sample showed a tendency to return to its original shape. The achieved results show that Luffa cylindrical fiber is suitable and possibly to be used in composites for engineering applications and indicate the high potential of thermomechanical and thermo-hydro-mechanical treatments to improve the properties of this natural fiber.

摘要

对丝瓜纤维的热机械和热流体力学处理进行了研究. 处理包括在干燥条件（热机）和饱和条件（热机）下对纤维进行热压，目的是降低纤维材料的孔隙率和增加弹性模量. 在25、120、160和200℃下进行热机械处理. 通过拉伸强度、吸湿性、扫描电镜（SEM）、X射线衍射和热重分析等手段研究了该处理方法的效果. 经处理后，纤维表现出较高的弹性模量和较低的吸湿性. 对于在160℃下压制的饱和纤维，由于其弹性模量增加了95%，并且在室温下相对于压缩纤维的吸湿性降低了22%，因此获得了最佳结果. 当暴露在高温和潮湿环境中时，致密化的样品显示出恢复其原始形状的趋势. 研究结果表明，丝瓜纤维具有良好的工程应用前景，在复合材料中具有广阔的应用前景，热机械和热流体力学处理是改善丝瓜纤维性能的重要手段.

KEYWORDS:

• Luffa cylindrical fiber
• natural fibers
• mechanical properties
• thermomechanical
• thermo-hydro-mechanical treatments

关键词:

• 丝瓜纤维
• 天然纤维
• 力学性能
• 热机械热-水-机械处理

Acknowledgments

The authors would like to thank the laboratory multiuser of the Department of Chemistry and Catalysis Laboratory, Federal University of Uberlândia and the FAPEMIG, CAPES, and CNPq.

Declaration of competing interest

The authors have no competing interests to declare.

Additional information

Funding

This work was supported by FAPEMIG, CAPES, and CNPq (grant number process #30723/2017-8).