Development of Four Parabens Reference Materials Certified for Purity Mass Fraction by Mass Balance Approach

The need for pure organic reference materials for establishing traceability to the international system of units, validation of analytical methods and assuring quality of the measurement results has been increased recently. Mass balance approach was used for development of four reference materials from methyl, ethyl, propyl and butylparaben certified for purity mass fraction. The analyte mass fraction in each reference material was assigned by measurements of detectable impurity components include determination of organic, inorganic, water and volatile impurities by HPLC–DAD and GC–FID, IC, Karl Fisher and headspace, respectively. Assignment of certified purity was based on results from independent liquid and gas chromatographic methods. The certified purity values of methyl, ethyl, propyl, and butylparaben and their corresponding expanded uncertainties (k = 2.0) were found (998.48 ± 0.71), (997.80 ± 1.36), (998.20 ± 0.51) and (998.35 ± 0.89) mg/g, respectively. The prepared reference materials can be used as a measurement standard for analytical instruments and as a control sample for assuring quality of cosmetics, pharmaceutical and food products.     

Metrologically Traceable Determination of the Water Content in Biopolymers: INRiM Activity

Water content in materials is a key factor affecting many chemical and physical properties. In polymers of biological origin, it influences their stability and mechanical properties as well as their biodegradability. The present work describes the activity carried out at INRiM on the determination of water content in samples of a commercial starch-derived biopolymer widely used in shopping bags (Mater-Bi\(^{\circledR })\). Its water content, together with temperature, is the most influencing parameter affecting its biodegradability, because of the considerable impact on the microbial activity which is responsible for the biopolymer degradation in the environment. The main scope of the work was the establishment of a metrologically traceable procedure for the determination of water content by using two electrochemical methods, namely coulometric Karl Fischer (cKF) titration and evolved water vapour (EWV) analysis. The obtained results are presented. The most significant operational parameters were considered, and a particular attention was devoted to the establishment of metrological traceability of the measurement results by using appropriate calibration procedures, calibrated standards and suitable certified reference materials. Sample homogeneity and oven-drying temperature were found to be the most important influence quantities in the whole water content measurement process. The results of the two methods were in agreement within the stated uncertainties. Further development is foreseen for the application of cKF and EWV to other polymers.     

New Primary Standards for Establishing SI Traceability for Moisture Measurements in Solid Materials

A European research project METefnet addresses a fundamental obstacle to improving energy-intensive drying process control: due to ambiguous reference analysis methods and insufficient methods for estimating uncertainty in moisture measurements, the achievable accuracy in the past was limited and measurement uncertainties were largely unknown. This paper reports the developments in METefnet that provide a sound basis for the SI traceability: four new primary standards for realizing the water mass fraction were set up, analyzed and compared to each other. The operation of these standards is based on combining sample weighing with different water vapor detection techniques: cold trap, chilled mirror, electrolytic and coulometric Karl Fischer titration. The results show that an equivalence of 0.2 % has been achieved between the water mass fraction realizations and that the developed methods are applicable to a wide range of materials.     

Modelling the optimum hot workability of TiB reinforced Ti-6Al-4 V alloy by stability maps

Hot workability of Ti-6%Al-4%V and two whisker discontinuously reinforced materials, Ti-6%Al-4%V/1.2%TiB and Ti-6%Al-4%V/8.9%TiB, have been investigated. Hot uniaxial compression tests were carried out using a computer controlled thermomechanical simulator Gleeble machine at temperatures in the range 850 °C to 950 °C and strain rates ranging from 1 to 50 s^?1. The microstructures and the compression test results were compared among the three materials. The Ti-6%Al-4%V/8.9%TiB material presented extensive cracking after deformation. In contrast, the Ti-6%Al-4%V/1.2%TiB material showed an interesting compromise between flow stress and workability. The parameters of the Garofalo equation were calculated for the three materials revealing apparent activation energies that increased with increasing TiB content. The modelling is carried out by stability maps that gives the temperature at a given strain rate to obtain optimal workability and the stresses that has to bear the equipment. Taken 5 s^?1 as a reference strain rate, the temperature required to obtain a quality product increased from about 1143 K (870 °C) for the Ti-6-4 alloy without TiB to 1228 K (955 °C) for the 1.2%TiB and to 1283 K (1010 °C) for the 8.9%TiB material. Therefore, the production of parts of the TiB composites should be conducted at a higher forming temperature to avoid the presence of cracks.     

甲醇中8组分苯系物溶液标准物质的研制

介绍甲醇中8组分苯系物溶液标准物质的研制过程。采用气相色谱仪(GC-FID)、电感耦合等离子体质谱仪(ICP-MS)和卡尔·费休水分仪(KF)等检测方法,结合质量平衡法对原料纯度进行验证,其纯度验证结果与证书标示值一致,并在不确定度范围内。经F检验和t检验,结果表明,采用重量-容量法制备的甲醇中8组分苯系物溶液标准物质具有良好的均匀性和稳定性,其定值结果为1000μg/mL,相对扩展不确定度为3%(k=2)。该溶液标准物质可用于环境分析中苯系物含量的测定和量值溯源。     

Certification of Three Reference Materials for α- and γ-Tocopherol in Edible Oils

Tocopherols are important vegetable oil constituents, and their reliable quantitative analysis depends largely on the existence and quality of certified reference materials (CRMs) which provides traceability of the measurement results to the SI units. Since there is a lack of suitable CRMs in case of tocopherols analysis, three matrix reference materials from corn, peanut and soybean oils were certified for the content of α and γ-tocopherols. Homogeneity and stability of the prepared reference materials were studied and certification was done by two independent chromatographic analytical methods. The measurement results were statistically treated and the certified values of α and γ-tocopherol in corn, peanut and soybean oils were assigned and their associated expanded uncertainties were estimated as: 322.04 ± 8.62, 771.48 ± 15.31, 106.23 ± 5.19, 108.94 ± 9.72, 140.66 ± 5.93, 418.00 ± 14.36 mg/kg, respectively. These values were found useful for many food testing laboratories in validation of analytical methods and analytical quality control.     

Lubricant Oils as a Certified Reference Material for Cleveland Open Cup Flash Point Testers

The flash point is an important indicator for the flammability of the liquid materials and also in the development of safe practices for handling and storage of these materials. The production of certified reference materials is essential to guarantee the performance of the flash point measurement apparatus so that it can be trusted and acceptable for its intended use. In this work lubricant oils of high molecular weight hydrocarbons (HM1, and HM2) were tested as certified reference materials in accordance with ISO guide 34 and 35 by using the high flash point temperature detector Cleveland-open cup as per ASTM D-92. The selected oils were tested for uncertified properties like pour point, viscosity, cloud point, density, and total acid number. The thermal analysis techniques DSC, and TGA were used to ensure the thermal stability of the lubricant oils and its ability to be used as high temperature flash point reference material. The certified value of the flash point temperature was assigned upon evaluation of the data acquired in an inter-laboratory comparison involving expert laboratories using the same measurement method. The certified values of the candidate reference materials with expanded uncertainty (coverage factor K = 2, approximate 95% confidence level) calculated using the results of the characterization, calibration (organizer lab), homogeneity, and stability assessment were 232 ± 9 °C for HM1, and 242 ± 10 °C for HM2.     

Reduction of cement content in renderings with fine sanitary ware aggregates

The aim of this research is to present a viable solution for the reduction of cement content in mortars, by recycling a non-biodegradable material, such as grinded sanitary ware fines. This research analysed the reduction of cement content from a volumetric ratio of 1:4 (cement: aggregates) to 1:5 and 1:6 with simultaneous incorporation of fines from sanitary ware waste (SWW). The fines incorporated were below 149 μm and were incorporated as 20 % of the aggregates volume. Several tests were carried out in the fresh and hardened states, namely water retention, flexural and compressive strengths, water absorption by capillarity, permeability to water under pressure and to water vapour and dimensional instability. It was found that the reduction of cement content and incorporation of SWW allowed better performance on most of the tests than that of the reference mortar (1:4 ratio).     

SI-Traceable Water Content Measurements in Solids,Bulks, and Powders

Methods such as Karl Fischer titration and Loss-on-Drying, commonly used for estimating moisture content in samples, have been in existence for many years, but have difficulties obtaining a direct calibration chain toward water content. In recognition of this challenge, the joint research project, METefnet, was funded by the European Metrology Research Programme in 2012. The goal of METefnet is to establish a European metrology infrastructure for water content measurement and to develop primary standards for unambiguous determination of water mass fraction in materials. Here, we describe the primary standard developed by Danish Technological Institute in METefnet. This standard establishes traceability of the water content of a sample to dewpoint temperature. The standard only measures water, and the measurement result is not affected by other components.     

Adiabatic Calorimetry as Support to the Certification of High-Purity Liquid Reference Materials

The certification of high-purity liquid reference materials is supported by several analytical techniques (e.g., gas chromatography, liquid chromatography, Karl Fischer coulometry, inductively coupled plasma mass spectrometry, differential scanning calorimetry, adiabatic calorimetry). Most of them provide information on a limited set of specific impurities present in the sample (indirect methods). Adiabatic calorimetry [1] complementarily provides the overall molar fraction of impurities with sensitivity down to few μmol · mol⁻¹ without giving any information about the nature of the impurities present in the sample (direct method). As the combination of adiabatic calorimetry with one (or more than one) indirect chemical techniques was regarded as an optimal methodology, NMi VSL developed an adiabatic calorimetry facility for the purity determination of high-purity liquid reference materials [2]. Within the framework of collaboration with NMIJ, a benzene-certified reference material (NMIJ CRM 4002) from NMIJ was analyzed by adiabatic calorimetry at NMi VSL. The results of this measurement are reported in this paper. Good agreement with the NMIJ-certified purity value (99.992 ± 0.003) cmol · mol⁻¹ was found. The influence of different data analysis approaches (e.g., extrapolation functions, melting ranges) on the measurement results is reported. The uncertainty of the measured purity was estimated.     

International Comparison on Thermal-Diffusivity Measurements for Iron and Isotropic Graphite Using the Laser Flash Method in CCT-WG9

The first international pilot study of thermal-diffusivity measurements using the laser flash (LF) method was organized by the working group 9 (WG9) of the Consultative Committee for Thermometry (CCT) of the Bureau International des Poids et Mesures (BIPM). Four National Metrology Institutes (NMIs) participated in this comparison. Thermal-diffusivity measurements on the Armco iron and the isotropic graphite IG-110 were carried out from room temperature to about 1200 K. The sample sets consist of five disk-shaped specimens of 10 mm in diameter and (1.0, 1.4, 2.0, 2.8, and 4.0) mm in thickness, each cut from the same block of material. These sample sets were specifically prepared for the comparison and sent to the participants. In the pilot comparison, the thermal diffusivity of each sample was estimated using the LF method with a specific extrapolating procedure. This procedure has the advantage of determining the inherent thermal diffusivity of the material. The extrapolated value in a plot of measured apparent thermal-diffusivity values versus the amplitude of the output signal corresponding to the temperature rise during each measurement is defined as the inherent thermal diffusivity. The overall results showed good agreement between independent laboratories, measurement equipment, and specimen thicknesses. The thermal diffusivities of the materials were determined using our measured results. A quantitative evaluation of the variability of the data obtained by the participants has been done, by evaluating the deviations from the reference value, the Z-value, and the En-number. Some data showed a large deviation from the reference value. It was concluded that these are caused by an insufficient time response of the measurement equipment and some difficulties with changing the pulsed heating energy. The effect of the thermal expansion on the thermal diffusivity was checked. It was found that the thermal-expansion effect was very small and negligible in this case.     

系列液体和固体水分标准物质的研制

针对水分检测领域对标准物质的需要,研制了系列水分标准物质,包括4种液体水分标准物质,量值覆盖范围为0.139~47.6 mg/g,不确定度范围为0.012~1.1 mg/g;还包括3种含结晶水化合物水分标准物质,量值覆盖范围为50.7~156.3 mg/g,不确定度范围为0.6~1.3 mg/g,以及3种混合物水分标准物质,量值覆盖范围为0.142~9.90 mg/g,不确定度范围为0.013~0.20 mg/g。该系列液体和固体水分标准物质,适用于卡尔·费休库仑法和容量法水分仪的校准和检定,以及水分测量方法的验证,能够保障我国水分检测的量值准确和等效一致。     

基于Karl Fischer电位滴定原理的超微量液体容积精密测量方法

为克服静力称重法受蒸发量影响大的不足,同时适应在线测量的需要, 根据法拉第定律和Karl Fischer电化学分析原理,研究了超微量液体电位滴定测量法。通过测量电解过程中所消耗电量进行微量液体水含量的计算,并结合液体密度测量可以计算出超微量液体容积。设计了这种非静力称重方法的测量系统,采用与静力称重测量系统比对试验的方式对这2种方法进行了验证,试验数据表明超微量液体电位滴定测量法和静力称重法测量结果具有良好的一致性,均符合ISO 8655的技术要求,但测量值偏大。与静力称重法相比,对测量环境要求低,易于实现在线测量,而且可以有效减少液体蒸发对测量结果的影响。     

The effect of ZrO2 and TiO2 on solubility and strength of apatite–mullite glass–ceramics for dental applications

The effect of ZrO₂ and TiO₂ on the chemical and mechanical properties of apatite–mullite glass–ceramics was investigated after sample preparation according to the ISO (2768:2008) recommendations for dental ceramics. All materials were characterized using differential thermal analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. X-ray fluorescence spectroscopy was used to determine the concentrations of elements present in all materials produced. The chemical solubility test and the biaxial flexural strength (BFS) test were then carried out on all the samples. The best solubility value of 242 ± 61 μg/cm² was obtained when HG1T was heat-treated for 1 h at the glass transition temperature plus 20 °C (T_g + 20 °C) followed by 5 h at 1200 °C. The highest BFS value of 174 ± 38 MPa was achieved when HG1Z and HG1Z+T were heat-treated for 1 h at the T_g + 20 °C followed by 7 h at 1200 °C. The present study has demonstrated that the addition of TiO₂ to the reference composition showed promise in both the glass and heat-treated samples. However, ZrO₂ is an effective agent for developing the solubility or the mechanical properties of an apatite–mullite glass–ceramic separately but does not improve the solubility and the BFS simultaneously.     

关于甲醇中水分测定的探讨和研究

本文将容量法的卡尔费休仪和库仑法的卡尔费休仪进行对比,并指出用不同的仪器测定水含量不同的MTO级甲醇和精甲醇,从而缩短了测定时间和在过程中产生的误差,更便捷地得到水含量,但卡尔费休法作为仲裁法,在测定过程中起着不可替代的指导作用。     

A Precision Ultrasonic Phase Velocity Measurement Technique for Liquids

Present paper reports the design and developmental aspects of a new technique for ultrasonic phase velocity measurement in liquids, which is based on the studies carried out on frequency dependence of ultrasonic velocity in pure, binary and ternary liquids/mixtures. The design and developmental aspects of the experimental set up are reported along with optimisation of data acquisition software developed in LabVIEW. Finally, the developed technique is used to measure phase velocity in water (W), aqueous solution of mannitol (M), binary mixture of tertiary butyl alcohol (TBA) in water and a tertiary mixture of TBA + W + M. The results are reported within frequency bandwidth from 3 to 7 MHz. The main reason for selecting these liquids was to identify some of the liquids which can be used as reference liquids for metrological applications. Although, reporting the systematic studies to find out the reference liquid is beyond the scope of the present paper due to obvious reasons, and will be dealt separately, but the studies certainly demonstrate that the technique can successfully be used for phase velocity measurement as a function of frequency and temperature.     

电商包装方式对水蜜桃运输缓冲防震及货架品质的影响

目的 研究常规电商包装中不同缓冲材料和包装量对水蜜桃在跌落、随机振动条件下的损伤防护及货架品质的影响。方法 以“华玉”水蜜桃为试材，分别采用瓦楞纸隔板+单盒包装、聚乙烯发泡棉(EPE)内衬+单盒包装、瓦楞纸隔板+两盒包装及EPE内衬+两盒包装等4种形式包装后，依据ISTA 3A标准开展模拟公路运输实验，分析水蜜桃货架期品质变化。结果 瓦楞纸隔板+两盒包装在面跌落时的加速度仅为90.306 m/s²，缓冲性能比单盒包装更好，但其在随机振动中响应较大，而EPE内衬+单盒包装处理受随机振动影响最小，一阶共振响应和二阶共振响应分别为0.012 2 g²/Hz和0.014 3 g²/Hz。模拟运输后在常温货架条件下，瓦楞纸隔板+两盒包装的水蜜桃在货架期内始终保持较低的呼吸强度和乙烯释放量，维持较好的外观品质。相较于单盒包装，两盒包装对维持水蜜桃质地、可溶性固形物、总酸含量及外观品质具有积极作用。结论 综合来看，以瓦楞纸隔板为缓冲材料，两盒包装更有利于水蜜桃电商物流运输中的震动防护，并能较好地保持货架品质，为适宜水蜜桃的电商物流包装...     

储存温度对不同包装材料包装的大米品质的影响研究

为了了解温度对不同包装材料包装的大米品质的影响规律,对不同包装材料包装的大米进行了温湿度加速试验,以大米的褐变值、含水量、脂肪酸含量、粘度、霉变为指标,研究了温度对大米品质的影响。结果表明,在相对湿度为90%时,随着储存温度升高和时间的延长,储藏大米的水分含量、粘度、明度值逐渐降低,脂肪酸含量急剧上升,并产生以青霉、黑霉为主的霉菌。     

Study of the influence of experimental conditions applied to the indirect tensile test versus type of bituminous mixture

The reference modulus of bituminous mixes, used for road design in France, is determined by the complex modulus measurement, carried out in the frequency domain at 15°C, 10 Hz or by the secant modulus in direct tension at 15°C, 0.02 s. However, there is strong interest to access this modulus using the indirect tensile (IT) test carried out in the time domain. Actually, this test appears to be easier to implement due to the sample manufacturing and numerous laboratories are already equipped. The present study proposes to determine the experimental condition to be applied to the IT test in order to get the reference modulus. A theoretical approach, based on the Maxwell and Huet viscoelastic linear models, is used to find the testing conditions at which the IT test has to be performed to give as precisely as possible the reference modulus. This procedure is applied on a large database of materials for which the viscoelastic spectrum has been provided. The influence of the loading waveform, which cannot be systematically controlled, is studied. For a force increasing linearly with time, the temperature at which the IT test has to be performed is close to 10°C, whatever the bituminous mix type. Moreover, the error that would have been committed by applying the equivalent temperature T_eq = 10°C during the indirect tensile test is evaluated. This error depends on the loading waveform but always remains, theoretically, under 1000 MPa. This study has been carried out in the framework of collaboration between LCPC and USIRF (Union des Syndicats de l’Industrie Routière française).     

Numerical optimization of hole making in GFRP composite using abrasive water jet machining process

Machining of composite materials for the production of bolt holes is essential in the assembly of the structural frames in many industrial applications of glass fiber-reinforced plastic (GFRP). Abrasive water jet cutting technology has been used in industry for such purposes. This technology has procured many overlapping applications and as the life of the joint in the assembled structure can be critically affected by the quality of the holes, so it is important for the industry to understand the application of the abrasive water jet cutting process on GFRP composite materials. The aim of the present work is to assess the influence of abrasive water jet machining parameters on the hole making process of woven-laminated GFRP material and to find the optimum values of the process parameters. Statistical approach was used to understand the effects of the predicted variables on the response variables. Analysis of variance was performed to isolate the effects of the parameters affecting the hole making in abrasive water jet cutting. The results show that the optimum values of cutting feed, fiber density, water jet pressure, standoff distance, and abrasive flow rate upon the response variables are 0.3 m/min, 0.82 g/cm³, 150 MPa, 2 mm, and 100 g/min, respectively.