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

Abstract

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 ®). 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.

Flexible, High‐Density and Water‐Resistant Polypropylene/Thermoplastic Elastomer/Inorganic Fillers Composites

“…Flexibility and impact toughness are properties that are normally decreased as the inorganic filler content increases. [ 23–30 ] However, this research shows the preparation of a novel high‐density PP/TPE/BaSO 4 composite that exceeds the blend impact toughness. Water content and absorption tests were also realized to ensure that the composites are functional and able to operate in wet environments.…”

Quantitative determination of bound water in cardboard by measurement of dielectric permittivity

“…To analyze the proportions of the various forms of water (free and bound) that exist in cardboard we used the thermocoulometric method, also called evolved water vapor analysis [13]. The thermo-coulometer ( EasyH 2 O thermo-coulometer, Berghof Products + Instruments GmbH, Germany) uses a P 2 O 5 sensor to selectively quantify the water content by Faraday's law.…”

Calibration and Uncertainty Estimation for Water Content Measurement in Solids

“…In chemistry, PMMs are gravimetry, titrimetry, isotope dilution mass spectrometry and coulometry [12], an example of the latter being EWV. Despite being PMMs, recent publications have demonstrated the usefulness of calibrating EWV and Karl Fischer titration (KFT), when highly accurate results are desired [13][14][15]. As PMMs, EWV and KFT are used to calibrate secondary measurement methods, to ensure traceability to SI units [10,16].…”