REGAIN & MOISTURE CONTENT

•  Regain is defined as the weight of water  in a material expressed as a percentage of the oven dry  weight. 
• Moisture content is the weight of water in a material expressed as percentage of the total weight. 

• let oven dry weight = d
• weight of water =W
• Regain = R
• Moisture Content = M

Mechanisms of moisture absorption

Mechanisms of moisture absorption 

• Moisture absorption in textile fibers occurs through the interaction of water molecules with polar groups within the structure (e.g. OH, -COOH). 
•  In ordered (crystalline) parts of the structure, these polar groups are not attached but in disordered (amorphous) regions there can be very free groups which can act as hooks with which the water molecules can link through hydrogen bonding. 
• Thus the absorption of moisture takes place in the amorphous regions only.

Atmospheric Condition And Relative Humidity

• Among other thing , the regain of a textile material depends upon the amount of moisture present in the surrounding air. The dampness, of the atmosphere can be described in terms of humidity either absolute humidity or relative humidity. 

Moistures in Textile

Introduction

taken form google

• The properties of textile fibers are strongly affected by the atmospheric moisture content.  
• Many fibers, particularly the natural fibers are hygroscopic in nature and they will absorb moisture if kept in a humid atmosphere. 
• Conversely, they will tend to lose moisture in a dry atmosphere (a process known as desorption.) 
• Hydrophobic fibers (e.g. Polyester) are those which do not absorb moisture if kept in a humid atmosphere.