Fuktkoncentrationen

Fuktkoncentrationen, commonly referred to as moisture content, is a material property describing how much water is present in a substance. It is usually expressed as a percentage of water relative to total mass (wet basis) or to the dry mass (dry basis). Typical expressions include dry-basis moisture content (m_w / m_dry × 100%) and wet-basis moisture content (m_w / m_total × 100%), with other units such as grams of water per gram of dry matter or per unit volume also used in specific contexts.

In many materials, moisture content is not fixed but depends on environmental conditions. The equilibrium moisture content (EMC) is the moisture level a material would reach at a given temperature and relative humidity. Sorption isotherms describe how EMC varies with humidity, often showing hysteresis between adsorption and desorption. Temperature influences both the amount of water a material can hold and the rate of moisture exchange.

Measurement and estimation: Oven-drying (loss-on-drying) is a common standard method where samples are weighed, dried to constant mass, and the moisture content is calculated from weight loss. Other methods include Karl Fischer titration for precise water content in liquids, and rapid handheld meters based on capacitance or resistance for solids. Dynamic vapor sorption and related gravimetric techniques provide detailed sorption data and EMC curves.

Applications and implications: Moisture concentration affects mechanical properties, dimensional stability, and shelf life in products such as wood, paper, textiles, foods, and polymers. Accurate moisture data are essential in drying processes, quality control, storage, and modeling of material behavior. See also moisture content, sorption isotherm, and equilibrium moisture content.