Polydimethylsiloxane wrapped aluminum diethylphosphinate for enhancing the flame retardancy of polyamide 6

Aluminum diethylphosphinate (ADP) was wrapped with polydimethylsiloxane (PDMS) by a facile method to improve its hydrophobic properties. The morphology and properties of PDMS-modified ADP (PDMS-ADP) were investigated by thermogravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and water contact angle tests. The water contact angle of PDMS-ADP was increased from 126° to 151° as compared with that of ADP, which indicates that PDMS-ADP showed good hydrophobic properties. Then, ADP and PDMS-ADP were introduced into polyamide 6 (PA6) matrices to study the flame retardancy of the composites. The flammability of the PA6/ADP and PA6/PDMS-ADP composites was much lower than that of pure PA6. The composites PA6-1 (with the addition of 15 wt% ADP) and PA6-4 (with the addition of 12 wt% PDMS-ADP) could pass the UL-94 V-0 in the vertical burning test. Meanwhile, the peak heat release rates of PA6-1 and PA6-4 were 212 and 192 kW/m², with reductions of 67.3 and 70.4%, respectively, compared with pure PA6. These results indicated that the coating of PDMS could enhance the flame-retardant efficiency of ADP.     

Extraction of toluene,o-xylene from heptane and benzyl alcohol from toluene with aqueous cyclodextrins

The separation of aromatic compounds (toluene and o-xylene) from heptane and of benzyl alcohol from toluene with aqueous solutions of cyclodextrins has been experimentally investigated, because cyclodextrins and its derivatives can selectively incorporate several organic compounds, whereas the separation of the aqueous solution of complexed cyclodextrins from the organic feed is simple. Cyclodextrins are not soluble in organic liquids, but cyclodextrin derivatives are highly soluble in water. Hydroxypropyl-β-cyclodextrins with different degrees of substitution and methylated β-cyclodextrin were selected for the extraction of toluene and o-xylene from heptane. Hydroxypropyl-β-cyclodextrin (two different substitution degrees) and hydroxypropyl-α-cyclodextrin were selected for the extraction of benzyl alcohol from toluene. The liquid–liquid distribution experiments were carried out at room temperature. Toluene and o-xylene form 1:1 complexes with different cyclodextrins and heptane can form 1:1 to 1:3 complexes. Benzyl alcohol forms 1:3 complexes with hydroxypropylated cyclodextrins. The models developed describe the experimental data reasonably well, considering the large deviations in the analyses.Aqueous cyclodextrin solutions are not feasible for the separation of aromatic components from aliphatic hydrocarbons, due to low distribution ratios of toluene (0.05) and o-xylene (0.023) between the aqueous and organic phase. With high distribution ratios of benzyl alcohol, between 0.3 and 2.2 depending on the CD concentration (at a solvent-to-feed ratio of 1) and a benzyl alcohol/toluene selectivity of at least 100, aqueous hydroxypropylated cyclodextrin solutions have sufficient potential for extracting benzyl alcohol from toluene.     

SAPO-34 分子筛改性聚丙烯复合材料性能研究

不同添加量的 SAPO-34 分子筛作为添加剂, 对聚丙烯材料进行改性。通过挤出注塑制备出 SAPO-34 分子 筛聚丙烯复合材料。采用示差同步扫描热分析仪 (TG-DSC)、X 射线衍射仪 (XRD)、扫描电子显微镜 (SEM) 等对改 性前后的聚丙烯复合材料的结构进行表征, 并通过万能材料试验机和摆锤式冲击试验机等研究了复合材料的力学性 能。研究结果表明: SAPO-34 分子筛的添加对聚丙烯材料的力学性能具有显著的提升作用, SAPO-34 分子筛添加量 在 5% 时可达到最大的拉伸与冲击强度, 最大拉伸强度可达 1 171 N, 相比纯聚丙烯材料提高了 14.5%; 最大冲击强 度可达 6.39 kJ/m², 提高了 47.2%。     

拟薄水铝石的制备最新进展及其应用

由于具有高比表面积、大孔容等特点,拟薄水铝石可以作为黏结剂、催化剂载体和原料应用于工业中。重点介绍了制备条件对拟薄水铝石性质的影响,并分析了醇铝盐水解机理。评述了拟薄水铝石在催化领域中的应用,并展望了醇铝法制备拟薄水铝石的发展趋势。     

废弃磺酸树脂改性聚丙烯复合材料的制备及力学性能提升

使用废弃磺酸树脂作为添加剂,添加不同含量对聚丙烯材料进行改性,得到一系列磺酸树脂/聚丙烯复合材料.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等手段对改性前后的聚丙烯复合材料进行表征,通过万能材料试验机和摆锤式冲击试验机等研究了复合材料的力学性能.研究结果表明:磺酸树脂的添加对聚丙烯材料的力学性能具有一定的提升...     

Near-infrared photo-responsive Er3+-K+ co-doped Y2O3 phosphors with enhanced UC luminescence

Y₂O₃: x% Er³⁺ (x=5, 7, 10, 12, 15) and Y₂O₃: 10% Er³⁺，x% K⁺ (x=0, 1, 3, 5, 7, 10, 15) phosphors were successfully prepared by a low-temperature combustion method. The structure as well as the absorption/emission spectra of phosphors were investigated. The effect of doping concentration of K⁺ ions on the upconversion (UC) luminescence of Y₂O₃: 10% Er³⁺ phosphor was examined and the possible optical transitions were discussed. The results showed that K⁺ ion doping not only changed the microstructure and crystallinity of the phosphors, but also enhanced its UC luminescence intensity. The Y₂O₃: 10% Er³⁺, 7% K⁺ phosphor exhibit the strongest UC emission intensity. Compared with the Y₂O₃: 10% Er³⁺ phosphor, the UC luminescence intensity at 563 nm and 661 nm was enhanced by 67.8 and 27.3 times for the K-codoped samples, respectively. The phosphor with the optimal doping concentration was mixed with a polymer to form a composite film, which was employed for the fabrication of near-infrared (NIR) photo-responsive detection devices. The device exhibited strong photo-current response to NIR light at 980 nm, implying that our work could inspire new design strategy for the development of NIR photo-detection devices.     

Thermochromic Pr3+ doped CaMoO4 phosphor with diverse thermal responses for temperature sensing

CaMoO₄:Pr³⁺ thermochromic phosphors with diverse thermal responses for temperature sensing were prepared by the traditional solid-phase reaction method. The typical CaMoO₄:Pr³⁺ had scheelite structure belonging to tetragonal crystal system and space group of I4₁/a (88). Pr³⁺ ions can be easily substituted for Ca²⁺ ions of host CaMoO₄ because of similar ionic radius. CaMoO₄: 1.5% Pr³⁺ have the block structure with mean size of 6.84 μm. The E_g (∼3.93 eV) value of pure CaMoO₄ is bigger than that (∼3.65 eV) of CaMoO₄: 1.5%Pr³⁺, attributing to the existence of intermediate defect energy levels. Appropriate Pr³⁺ doping concentration is 1.5%, and the concentration quenching phenomenon can be explained by the concrete electric multipole type of d-d interaction. The emission peak at ∼605 nm from ¹D₂→³H₄ transition have a good thermal stability of 99.452%@423 K, while the wide band centered at ∼490 nm from ³T_1,2 → ¹A₁ transition in the MoO₄²⁻ complex and ³P₀→³H₄ transition in Pr³⁺ have a poor thermal stability of 27.572%@423 K. Calculated activation energy is 0.239 eV. Temperature-dependent FIR for optical thermometry was constructed due to their diverse thermal responses. CaMoO₄: Pr³⁺ phosphor had good relative sensitivities of 2.216%, 0.969% and 0.932% based on FIR of I_{605 nm}/I_{490 nm} with Boltzmann distribution, modified Boltzmann distribution and exponential equation fitting. Thermochromic behavior and thermal quenching mechanism are investigated. The obtained relative sensitivity is better than that of most phosphors, implying that CaMoO₄: Pr³⁺ has a potential for application in optical thermometry.