Unraveling the film-formation kinetics of interfacial polymerization via low coherence interferometry

Interfacial polymerization (IP) is one of the most important methods for fabricating thin film composite (TFC) membranes. Understanding the film-formation mechanisms is of great value for developing membranes with enhanced performance. This work proposed a novel method to in situ characterize the film-formation kinetics via low coherence interferometry (LCI). The polyamide film formed at the liquid–substrate interface was scanned in real time; the polymerization induced significant variations in the optical properties around the reaction zone. After mitigating the effects of the perturbed interface, the surface-averaged intensity profiles provide a solid basis for analyzing the film-formation kinetics at various depths. In particular, the effects of the monomer concentrations were investigated to reveal the asymmetric growth and development of irregular substructures. All the characterization results confirm that the LCI-based characterization is a powerful tool for studying the structural evolution of the IP layer and thereby providing deeper insights for optimizing TFC membranes.     

铝碳质长水口用低铝抗氧化涂层的研制

为抑制铝碳质长水口使用过程中石墨的氧化，其表面会涂覆含 20%~30%Al₂O₃的抗氧化涂层，但切割丝钢等特种钢冶炼过程必须严格控制钢液中夹杂的 Al₂O₃的含量，因此需要制备低氧化铝含量的抗氧化涂层。本文通过调节涂料组成、加水量和水玻璃加入量制备了低铝抗氧化涂层，并利用扫描电镜分析了抗氧化实验后试样断口的显微结构。结果表明：以粘土粉、钾长石粉和硅砂为主要原料，添加 10%硼砂的涂料可在 800 ℃形成良好的釉层，此时涂料中 A12O3的含量可降至 12%，得到了低铝涂料；当加入占涂料质量 80%的水和 40%的水玻璃时，涂层具有最佳的涂覆性能和抗氧化性能，涂层和长水口基体结合致密，保护了长水口中的石墨不被氧化。     

低剂量抑制剂Inhibex501存在下的甲烷水合物相平衡研究

含动力学抑制剂的天然气水合物相平衡研究对新型低剂量抑制剂的开发具有指导作用。在283.6 ~ 290.9 K和7.51 MPa ~ 15.97 MPa的温压范围内研究了抑制剂Inhibex501及其溶剂2-乙二醇单丁醚对甲烷水合物相平衡条件的影响。实验结果显示，0.5wt%和2.0wt%浓度的Inhibex501对甲烷水合物形成的热力学条件具有促进作用，能使甲烷水合物形成移向更高的温度或者更低的压力，而2-乙二醇单丁醚在浓度0.2wt% ~ 1.0wt%范围几乎不改变甲烷水合物形成的热力学条件，N-乙烯基己内酰胺与N-乙烯基吡咯烷酮的共聚物对水合物形成热力学条件的改变起主要作用。     

Effects of skim milk concentrate dry matter and spray drying air temperature on formation of capsules with varying particle size and the survival microbial cultures in a microcapsule matrix

The impact of total solid (TS) content in combination with the feed rate and air inlet temperature on the survival of Lactobacillus paracasei ssp. paracasei F19 after spray drying in a skim milk matrix has been investigated and correlated with the capsule size. Depending on the experimental conditions, the survival rates ranged from 64 to 0.2%. The higher the air inlet temperature, the lower was the survival rate and an inversely correlation between the TS content and particle size has been determined. These results clearly indicate that process stress analyses and product-related characteristics must not be regarded separately.     

Core–shell type multi‐arm azide polymers based on hyperbranched copolyether as potential energetic materials in solid propellants

A series of novel multi‐arm azide copolymers (POGs) with the same hyperbranched poly[3‐ethyl‐3‐(hydroxymethyl)oxetane] core (PEHO‐c) and different content of linear glycidyl azide polymer shell (GAP‐s) have been synthesized by sequential cationic ring‐opening polymerization and azidation. Detailed structural information of these copolyethers was deduced from Fourier transform infrared, ¹H NMR and inverse gated decoupled ¹³C NMR spectroscopies, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, gel permeation chromatography and elemental analysis. The molecular weight of POG having GAP‐s and PEHO‐c with a molar ratio 14.95:1 (R_s/c) was around 31 000 g mol^?1, far above that of linear GAP (around 4000 g mol^?1). The apparent viscosity and glass transition temperature (?51 to ?23 °C) decreased first and then slightly increased with increasing molecular weight. Thermal analysis revealed that all the obtained POGs exhibited excellent resistance to thermal decomposition up to 220 °C. Moreover, the energetic properties, investigated using oxygen bomb calorimetric measurements, indicated that the enthalpy of formation of the POGs was higher than that of general linear GAP, but similar to that of branched GAP under reasonable R_s/c. The compatibilities of the POGs with common materials used in solid propellants were studied using differential scanning calorimetry and the results indicated that the POGs had good compatibility with these materials. © 2017 Society of Chemical Industry     

Properties of polyamide 6,10/poly(vinyl alcohol) blends and impact on oxygen barrier performance

The oxygen transmission rate, average volume of free‐volume cavities (V_f) and fractional free volume (F_v) of polyamide 6,10 (PA610)/poly(vinyl alcohol) (PVA) (i.e. PA610_xPVA⁰⁵_y, PA610_xPVA⁰⁸_y and PA610_xPVA¹⁴_y) blend films reduced to minimum values when their PVA contents reached corresponding optimal values. Oxygen transmission rate, V_f and F_v values obtained for optimal PA610_xPVA^z_y blown films were reduced considerably with decreasing PVA degrees of polymerization. The oxygen transmission rate of the optimal bio‐based PA610₈₀PVA⁰⁵₂₀ blown film was only 2.4 cm³ (m²·day·atm)^?1, which is about the same as that of the most often used high‐barrier polymer, ethylene–vinyl alcohol copolymer. Experimental findings from dynamic mechanical analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction and Fourier transform infrared spectroscopy of the PA610_xPVA^z_y blends indicate that PA610 and PVA in the blends are miscible to some extent at the molecular level when the PVA contents are less than or equal to the corresponding optimal values. The considerably enhanced oxygen barrier properties of the PA610_xPVA^z_y blend films with optimized compositions are attributed to the significantly reduced local free‐volume characteristics. © 2017 Society of Chemical Industry