本研究旨在研究紫外线C(UVC)辐射对低密度聚乙烯(LDPE)食品包装的影响。主要目标包括评估LDPE降解和使用放置在LDPE样品下的热释光剂量计(TLD)检测UVC辐射。暴露一小时后,结果确认准确的UVC检测,为优化食品处理程序提供了一个有用的工具。ATR-FTIR光谱分析显示UVC辐照的LDPE样品有细微的变化(透射率<8%),包括可能的CH断裂(2910和2848cm-1)和潜在的CC键振动(1470cm-1),在其他人中。然而,观察到的变化可能源于LDPE性能,而不是完全来自UVC辐射。对UVC诱导的热释光(TL)发射的比较研究提供了对各种TLD材料的见解。TL动力学分析,使用计算机辉光曲线去卷积(CGCD)方法,由于UVC暴露而公布的陷阱电荷激活,包括部分电离,漂白效应和光转移(PTTL)过程。LDPE样品放大了UVC-TL反应,揭示归因于PTTL过程的TLD之间的强度差异,由于缺乏退火处理而加剧。此外,TL探测器的化学成分,例如,type,浓度,number,其掺杂剂的氧化态和离子半径可能会影响UVC-TL响应。因此,TL强度比如下:GR-200(LiF:Mg,Cu,P)>TLD-100(LiF:Ti,Mg)>TLD-400(CaF2:Mn)>TLD-200(CaF2:Dy)。因此,GR-200检测电离辐射,但不能区分电离和非电离UVC辐射,而TLD-100作为UVC辐射探测器的有效性有限。相比之下,TLD-400适用于检测UVC辐射,TLD-200成为最有利的UVC检测器,显示一致的响应水平和最小的PTTL效应放置在LDPE样品下,而不需要热退火处理,使TLD-200在低成本测量方案中可重复使用。
This research aims to study the effects of ultraviolet C (UVC) radiation on low-density polyethylene (LDPE) food packaging. Main objectives include evaluating LDPE degradation and detecting UVC radiation using thermoluminescent dosimeters (TLDs) placed under LDPE samples. Results confirm accurate UVC detection after one hour of exposure, providing a useful tool for optimize food treatment procedures. ATR-FTIR spectroscopy analysis revealed subtle alterations (<8 % transmittance relative) in UVC-irradiated LDPE samples, including possible CH breakage (2910 and 2848 cm-1) and potential CC bond vibrations (1470 cm-1), among others. However, observed variations may stem from LDPE properties rather than entirely from UVC radiation. A comparative study of UVC-induced
thermoluminescence (TL) emissions provided insights into various TLDs materials. TL kinetic analysis, using computerised glow curve deconvolution (CGCD) method, unveiled trap charge activation due to UVC exposure, including partial ionization, bleaching effect and photo-transfer (PTTL) processes. LDPE samples amplified UVC-TL responses, revealing intensity differences between the TLDs attributed to the PTTL process, accentuated by the lack of an annealing treatment. Additionally, chemical composition of the TL detectors such as, type, concentration, number, oxidation states and ionic radii of their dopants may influence UVC-TL response. Consequently, TL intensity ratios follow as: GR-200 (LiF: Mg, Cu, P) > TLD-100 (LiF: Ti, Mg) > TLD-400 (CaF2: Mn) > TLD-200 (CaF2: Dy). Thus, GR-200 detects ionizing radiation but cannot distinguish between ionizing and non-ionizing UVC radiation, while TLD-100 has limited effectiveness as a UVC radiation detector. In contrast, TLD-400 is suitable for detecting UVC radiation and TLD-200 emerges as the most favorable UVC detector, showing consistent response levels and minimal PTTL effect placed under the LDPE samples without the need of a thermal annealing treatment that makes the TLD-200 to be reusable in a low-cost measurement protocol.