Micromechanical Characterization of Continuous Fiber Date Palm Composites

ABSTRACT

Date palm fiber composites with aligned, continuous fibers and epoxy matrix were prepared and mechanically characterized using micromechanical models. A hydrothermal process with microwave heating was utilized to extract the date palm frond (midrib) fibers, making the process eco-friendly as opposed to the commonly reported chemical extraction method. Single fibers were then characterized and found to have an average elastic modulus and ultimate tensile strength of 17.1 ± 1.5 GPa and 333 ± 27.4 MPa, respectively. Interfacial shear strengths ranging between 6 and 12 MPa were determined using a single-fiber pull-out test. Fibers were aligned to make uniaxial tensile samples with volume fraction ranging from 11% to 56%, elastic modulus ranging from 1.72 GPa to 9.52 GPa and ultimate tensile strengths ranging from 16.9 MPa to 43.8 MPa. All the results were found to obey “Rule of Mixtures” theory. The composite’s mechanical properties are similar to or exceeding those of the commercially available wood products such as medium density fiberboard, oriented strand board, thick particle board, hard fiber board, and plywood, making the hydrothermal approach with microwave heating as a promising approach for preparation of date palm composites and further opens up similar process pathway for other natural fibers.

摘要

制备了具有排列、连续纤维和环氧树脂基体的椰枣纤维复合材料，并使用微观力学模型对其进行了力学表征. 利用微波加热的水热工艺提取椰枣叶（中肋骨）纤维，与通常报道的化学提取方法相比，该工艺具有环保性. 然后对单纤维进行了表征，发现其平均弹性模量和极限拉伸强度分别为17.1 ± 1.5GPa和333 ± 27.4MPa. 界面剪切强度范围在6和12MPa之间，使用单纤维拉拔试验测定. 将纤维排列以制备体积分数为11–56%、弹性模量为1.72 GPa至9.52 GPa、极限拉伸强度为16.9 MPa至43.8 MPa的单轴拉伸样品. 所有结果均符合“混合物规则”理论. 该复合材料的机械性能类似于或超过可商购的木材产品，如中密度纤维板、定向刨花板、厚刨花板、硬纤维板和胶合板，使微波加热水热法成为制备椰枣复合材料的一种很有前途的方法，并进一步为其他天然纤维开辟了类似的工艺途径.

KEYWORDS:

• Date palm
• Natural fibers composite
• Epoxy
• Pullout
• Micromechanics
• Interfacial shear strength
• Aligned fiber

关键词:

• 椰枣
• 天然纤维复合材料
• 环氧树脂
• 拉出
• 微观力学
• 界面剪切强度
• 对齐光纤

Highlights

• Environmentally friendly hydrothermal extraction process used to reduce the use of chemicals

• Micromechanical models used to predict composite behaviors; experiments (single fiber, fiber pull-out and tensile) used to validate predictions

• Cellulosic fibers extracted from core of date palms fronds (midrib) demonstrated an elastic modulus and tensile strength of 17 GPa and 333 MPa, respectively

• Interfacial strengths between date palm fibers and epoxy matrix measured to be between 6 and 12 MPa

• Aligned fiber, uniaxial tensile samples with volume fraction between 11 and 56% characterized with ranges of elastic modulus from 1.72 GPa to 9.52 GPa and ultimate tensile strengths from 16.9 MPa to 43.8 MPa

Acknowledgments

The authors acknowledge support provided by the Deanship of Research Oversight and Coordinator at King Fahd University of Petroleum & Minerals for funding this work through Project INAM2209.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the King Fahd University of Petroleum and Minerals [INAM2209].