MACROMOLECULAR MATERIALS AND ENGINEERING
·
2021
·Vol. 306
·期 3
·2000606
·
IF 4.367
Pengfei Jiang,Jiulin Shen,Yao Wang,Jibin Zhang,Xiangfu Liu,Guoli Tu
Due to the development of dynamic flexible organic light-emitting diode displays, colorless polyimides (CPI) as the supporting or protecting optical films, are facing significant challenges due to the requirements of optical, mechanical, thermal, and chemical properties. Typical CPIs are derived from TFDB (2,2-bis(trifluoro-methyl)-4,4′-diaminobiphenyl)/6FDA (4,4′-(hexafluoroisopropylidene)diphthalic anhydride), which still need to be improved in both dimensional stability and optical performance. In this communication, a strong electron acceptor group, the sulfoxide bond, is first introduced into the TFDB block of CPI chains. Based on this introduction, the distribution of the electron cloud in the polymer chain is reconstructed under the strongly pulling electron effect, and the spatial conformation of the polymer chain is also affected by the rigid and twisted sulfoxide group. The influences on CPI's optical properties, especially the refractive index and the retardation, are studied and discussed in detail by experimental results and theoretical calculations. It is shown that the CPI with the sulfoxide group exhibits higher optical transparency, lower yellow index, phase retardation and coefficient of thermal expansion, which is an ideal material for CPI optical films.
研究领域:
材料科学
·
光学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2024
·Vol. 16
·期 13
·1891
·
IF 4.7
Guangshe Zhang,Li Zhang,Wencheng Gao,Riwei Xu,Kuke Ding
The decay of radon gas in soil and buildings produces alpha radiation, which is the second leading cause of lung cancer in humans. Therefore, by conveniently detecting radon gas in the environment, potential sources of danger can be identified early, and necessary measures can be taken to protect human health. Solid-state nuclear track detectors prepared from polyallyl diglycol carbonate (PADC) resin are the most sensitive detectors for alpha radiation released by radon gas. The traditional method of preparing PADC resin involves free radical thermal polymerization, which suffers from issues such as low polymerization efficiency, long processing time, and the occurrence of defects in the product. In this study, PADC resin was efficiently prepared using a UV initiator. Starting from the polymerization mechanism, experiments were designed using a controlled variable approach, and a rational polymerization apparatus was devised. By comparing the double bond conversion rate, transparency, hardness, and yellowness index of the polymers, the optimal initiator for PADC resin, 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), was selected. The influence of irradiation intensity, irradiation time, and UV initiator dosage was investigated. The performance of the polymers, including double bond conversion rate, optical properties, dynamic mechanical properties, etching rate, and track detection efficiency, was analyzed. The experimental conditions for preparing PADC resin were optimized: irradiation intensity of 12 mW/cm2, irradiation time of 25 min, and UV initiator dosage of 5 parts. The resulting resin polymer had a double bond conversion rate of 93.2% and a track detection efficiency of 0.714.
研究领域:
材料科学
·
辐射检测
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Food Bioscience
·
2024
·
IF 4.8
Tsekwi Gracious Rinwi,Da-Wen Sun,Ji Ma,Qi-Jun Wang
This study investigated the impact of isochoric freezing-thawing (ISF-T) cycles (C0–C5) on the quality of chicken breast. The results indicated a significant increase (P < 0.05) in pH from 5.41 to 5.96 after C1 to C4 before slightly decreasing to 5.72 (C5). Lightness (L*) varied between 50.13 and 44.55 across C1 to C4, with redness notably decreasing from −1.15 after C0 to −2.09 after C5 while yellowness (b) sharply increased from 2.65 (C0) to 4.65 (C5). Moisture content decreased from 74.01% to 68.13% after C5. WHC slightly reduced from 89.25% after C0 to 85.66% after C4, with an 83.78% reduction after C5. Cooking loss increased linearly across the ISF-T cycles from 18.08% reaching 24.14% after C5. Conversely, shear force decreased to 21.83 N after C5 from 25.21 N after C1. Protein solubility slowly increased to 88.79% after C3, then decreased to 72.84 after C5. The myofibrillar index remained stable until C3, then increased from 35.51 after C5. Lipid oxidation slowly increased to 0.27 mg MDA/kg after C3, then sharply increased to 0.44 mg MDA/kg after C5. In addition, Ca 2+ -ATPase activity showed that the samples obtained after C1 to C3 fluctuated between 23.59% and 24.71%, followed by a substantial reduction to 12.35% after C5. Furthermore, validation of the results by magnetic resonance imaging and nuclear magnetic resonance analysis confirmed the findings, suggesting that isochoric freezing could offer a viable solution to control temperature fluctuations, a challenging problem during meat storage and distribution in the cold chain food industry.
研究领域:
食品科学
·
肉类加工
·
物理化学
·
生物物理学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）