Barrier Dispersion-Based Coatings Containing Natural and Paraffin Waxes

Petroleum, synthetic, and natural waxes have been used as hydrophobic bases for dispersions intended for use as barrier coatings for packaging paper. Oil-in-water dispersions with alkaline pH were prepared by a two-step homogenization procedure containing paraffin wax, with various characteristics, the Fischer–Tropsch synthesis product or beeswax. The size of the dispersed particles determined by dynamic light scattering depended on the type of hydrophobic base used and was in the range of 350–440 nm. The ability of dispersion particles in aggregation driven by electrostatic attraction, evaluated by Zeta potential analysis by electrophoretic light scattering, was from −26 to −50 mV. Static multiply light scattering was used for 30 days of stability assessment and helped to select the dispersion with a Sarawax SX70 wax base as the most stable. Dispersions were further used for coating the backing of kraft paper by the Meyer rod method. Coated paper with an applied coating of 6 g/m² had very good hydrophobic properties (Cobb60 < 4 g/m²), sufficient strength properties, and air permeation, which enabled its application as a packaging material. The dispersions based on Sarawax SX70 wax were evaluated as the best coating for Mondi ProVantage Kraftliner 125 g/m² backing paper. Good hydrophobic properties and strength properties indicate the possibility of using the SX70-based wax dispersion coating as a replacement for PFAS coatings in some applications.     

Optimization of the Physical,Optical and Mechanical Properties of Composite Edible Films of Gelatin,Whey Protein and Chitosan

The aim of this work was to evaluate the effect of the concentration of gelatin (G) (3–6 g), whey protein (W) (2.5–7.5 g) and chitosan (C) (0.5–2.5 g) on the physical, optical and mechanical properties of composite edible films (CEFs) using the response surface methodology (RSM), as well as optimizing the formulation for the packaging of foods. The results of the study were evaluated via first- and second-order multiple regression analysis to obtain the determination coefficient values with a good fit (R ˃ 0.90) for each of the response variables, except for the values of solubility and b*. The individual linear effect of the independent variables (the concentrations of gelatin, whey protein and chitosan) significantly affected (p ≤ 0.05) the water vapor permeability (WVP), strength and solubility of the edible films. The WVP of the edible films varied from 0.90 to 1.62 × 10⁻¹¹ g.m/Pa.s.m², the resistance to traction varied from 0.47 MPa to 3.03 MPa and the solubility varied from 51.06% to 87%. The optimized values indicated that the CEF prepared with a quantity of 4 g, 5 g and 3 g of gelatin, whey protein and chitosan, respectively, provided the CEF with a smooth, continuous and transparent surface, with L values that resulted in a light-yellow hue, a lower WVP, a maximum strength (resistance to traction) and a lower solubility. The results revealed that the optimized formulation of the CEF of G–W–C allowed a good validation of the prediction model and could be applied, in an effective manner, to the food packaging industry, which could help in mitigating the environmental issues associated with synthetic packaging materials.     

控制系统故障诊断浅析

简要回顾了故障诊断技术的发展历程,介绍故障诊断的基本概念,着重综述基于模型故障诊断技术和不依赖于模型的智能故障诊断技术特点和发展概况.为未来故障诊断技术的发展提出了一些展望.     

疏水改性pH响应型智能水凝胶P(HEMA-NaAA-DiAC16)的制备及其溶胀性能

以二烯丙基胺和1-溴代十六烷为原料合成了疏水单体N,N-二烯丙基正十六烷胺(DiAC16),用FTIR、1H NMR 和元素分析对其进行了表征。 以2-羟基甲基丙烯酸乙酯(HEMA)、丙烯酸(AA)和N,N-二烯丙基正十六烷胺为共聚单体,N,N′-亚甲基双丙烯酰胺(BIS)为交联剂,十二烷基硫酸钠(SDS)为表面活性剂,过硫酸铵-四甲基乙二胺(TMEDA)为引发体系,制得的疏水改性智能水凝胶P(HEMA-NaAA-DiAC16)具有pH敏感特性。 研究了DiAC16、NaAA、BIS用量及pH值和离子强度等因素对水凝胶P(HEMA-NaAA-DiAC16)溶胀性能的影响。 结果表明,凝胶在水中的平衡溶胀率(为78.9～163.91),随DiAC16、BIS用量的增加和NaAA用量的减少而减少,n值(一般在0.5~1.0之间)随DiAC16、NaAA和BIS用量的增加而增加,为非Fickian扩散。 水凝胶的吸水溶胀是放热过程,ΔHm在-2.09～-3.64 kJ/mol,ΔHm的绝对值随DiAC16用量的减少、NaAA用量和BIS用量的增加而增大,聚合物与水的亲和力逐渐增强。 随离子强度的增强,平衡溶胀率下降。     

智能石墨消解–ICP–MS法测定空气PM2.5中的Pb和Cd

建立电感耦合等离子体质谱(ICP–MS)测定空气PM2.5中的Pb和Cd元素的分析方法。采用连续β射线–DHS PM2.5大气颗粒物浓度监测仪采集空气中的PM2.5,以智能石墨消解PM2.5滤膜样品,ICP–MS测定其中的Pb和Cd元素含量。在优化的仪器条件下,元素Pb和Cd标准曲线的线性相关系数均为0.999 9,检出限分别为0.018,0.52ng/m3,满足HJ 657–2013的要求。Pb和Cd的加标回收率分别为95.8%~101.4%,99.3%~104.9%,测定结果的相对标准偏差分别为4.20%和2.38%(n=6)。对滤膜标准样品进行了测定,测定结果与标准值一致。该方法测定结果准确、可靠,可用于测定空气PM2.5中的Pb和Cd。     

单扫示波极谱法测定食品包装材料中双酚A的研究

研究发现，在0.12mol/L Na2HPO4-KH2PO4(pH7.5)底液中，双酚A于峰电位（Ep)-1.0V(vs.SCE)处产生灵敏的极谱还原波，该波的二阶导数峰电流（ip)与双酚A浓度在2.0-10.0mg/L范围内呈良好的线性关系，检出限为1.0mg/L，萃取后测定，检出限为0.1mg/L。本法操作简便、快速、准确。用于食品包装材料中双酚A含量的测定，结果令人满意。     

智能型色谱整体固定相的研究进展

整体柱作为新一代色谱固定相,具有原位制备、快速传质和高通透性的特点,近年来引起人们的极大关注。智能型聚合物作为一类功能性材料,能在温度、pH和盐等环境因素的刺激下产生特异性响应变化,通常被修饰到固相载体表面用来构造环境敏感性材料,使得该智能材料在药物控释、化学传感和细胞生长等领域有着广泛的应用。因此,在整体柱上构造智能型表面更为其在色谱领域的发展提供了新的契机。本文主要综述了近年来智能型整体柱在色谱领域的研究进展。     

载银二氧化钛纳米管表面pH敏感膜构建及其抑菌特性

采用表面涂覆硅烷偶联剂KH550、两步光接枝、阳极氧化等方法,在钛表面成功制备出一种pH型敏感膜覆盖的载银二氧化钛（TiO₂）纳米管阵列。利用扫描电镜（SEM）、透射电镜（TEM）、能谱分析（EDS）、原子吸收光谱（AAS）对该pH敏感膜覆盖的载银TiO₂纳米管阵列理化性能进行了表征,采用抑菌环实验定性考察了样品的抗菌特性,并计算其抑菌率。结果表明,含银离子溶液在毛细管力作用下大量进入TiO₂纳米管中,并在pH型敏感膜的调控下,使银离子在不同pH环境下具备不同的释放行为,从而达到良好的控释效果;载银TiO₂纳米管的抑菌率与银离子负载量成正比,且抗菌性能持久。     

Triclosan‐based antibacterial paper reinforced with nano‐montmorillonite: a model nanocomposite for the development of new active packaging

In this study, a suitable method is reported to produce reinforced antibacterial paper packaging using the antimicrobial triclosan (TC) and organically modified montmorillonite (OMMT) as “model” compounds. Direct incorporation of TC at a concentration of 1 wt% and OMMT at concentrations of 1, 4, 7, and 10 wt% into papers was performed via coating process, and the resulting materials were characterized by in vitro antimicrobial assays, thermogravimetric analysis, scanning electron microscopy, mechanical tests, and water vapor transmission rate determinations. It was demonstrated that the presence of 1% TC in the coated papers exhibited inhibitory effects against Staphylococcus aureus and Escherichia coli. It was also pointed out that increases of approximately 30% in the tensile strength of commercial paper are obtained by using the OMMT at a concentration of 1 wt%. Water barrier property and thermal stability of paper were also enhanced because of the coating process and the incorporation of OMMT. The results from this study demonstrate that OMMT has a great potential to be incorporated into coating formulations to obtain antibacterial‐coated papers with improved properties for various packaging applications. Copyright © 2011 John Wiley & Sons, Ltd.     

纺织品与食品包装材料中烷基酚及双酚A迁移量的液相色谱-串联质谱分析

建立了纺织品与食品包装材料中烷基酚及双酚A迁移量的液相色谱-串联质谱分析方法.纺织品和食品包装材料浸泡液经Supelclean Envi-Carb石墨化碳黑固相萃取柱净化,以Waters XBridge C_(18)(150 mm×2.1 mm,3.5 μm)色谱柱分离后,进行LC-MS/MS多反应监测模式下的定性及定量分析.烷基酚和双酚A在纺织品模拟汗液、食品模拟物介质中特定迁移量的定量下限分别为2、4 μg/kg.在低、中、高3个添加水平下,测得纺织品样品的回收率为83%～91%,相对标准偏差为4.1%～9.0%;食品包装材料样品的回收率为82%～94%,相对标准偏差为3.9%～8.7%.