Nabi Rao Adeel Un, Khawaja Hassan Abbas, Liu Yaoxiang, Yang Chaopeng, Wang Tie-Jun
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics and CAS Center for Excellence in Ultra-intense Laser Science, Chinese Academy of Sciences Shanghai 201800 China
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences Beijing 100049 China.
RSC Adv. 2025 Jun 23;15(26):21089-21107. doi: 10.1039/d5ra02920a. eCollection 2025 Jun 16.
A particular laser harmonic with an effective combination of process parameters can break plastic bonds by surpassing the dissociation threshold. Exploring this direction is imperative to uncover new physics and chemistry related to laser-high-density polyethylene (HDPE) interactions and to understand the phenomena occurring during laser induced degradation. An experiment was conducted in an open-air environment using the first (1064 nm), second (532 nm), and fourth (266 nm) harmonics at a 20 Hz repetition rate, with pulse energies of 5-40 mJ for the first and second harmonics, and 3-10 mJ for the fourth harmonic. The findings revealed that all laser harmonics broke HDPE bonds, with the fourth harmonic being the most effective in directly breaking bonds, particularly C-H bonds, which was evident from a prominent Hα peak at 656.3 nm. The results demonstrate initial, partial, and post-bond breaking, which can address deficiencies in laser-HDPE recycling and enable laser-induced HDPE pyrolysis, which has not been investigated. Optical microscopic analysis showed that craters formed by the fourth harmonic were wider and exhibited more efficient photon absorption with minimal ablation. Additionally, a high confidence interval ( ) value of 0.9758 with increased electron density and plasma temperatures, further supports the efficiency of bond breaking.
具有有效工艺参数组合的特定激光谐波可以通过超过解离阈值来打破塑料键。探索这一方向对于揭示与激光-高密度聚乙烯（HDPE）相互作用相关的新物理和化学现象以及理解激光诱导降解过程中发生的现象至关重要。在露天环境中进行了一项实验，使用了重复频率为20 Hz的基频（1064 nm）、二次谐波（532 nm）和四次谐波（266 nm），基频和二次谐波的脉冲能量为5 - 40 mJ，四次谐波的脉冲能量为3 - 10 mJ。研究结果表明，所有激光谐波都能打破HDPE键，其中四次谐波在直接打破键尤其是C - H键方面最为有效，这从656.3 nm处明显的Hα峰可以看出。结果显示了键断裂的初始、部分和后期阶段，这可以弥补激光-HDPE回收中的不足，并实现尚未被研究的激光诱导HDPE热解。光学显微镜分析表明，四次谐波形成的坑更宽，并且在最小烧蚀的情况下表现出更有效的光子吸收。此外，随着电子密度和等离子体温度的增加，高置信区间（ ）值为0.9758，进一步支持了键断裂的效率。
