The Power of Water
Due to their hygroscopic nature, polyamides absorb humidity from their environment. This, in turn, influences the properties of the material and hence processing of the material. Even a small amount of water in Polyamide 6 (PA6) will drastically decrease its Temperatura di transizione vetrosaLa transizione vetrosa è una delle più importanti proprietà chimico-fisiche dei materiali amorfi e semi-cristallini, come, ad esempio, vetri, metalli (amorfi), polimeri, ingredienti farmaceutici e alimentari e definisce l’intervallo di temperatura in cui le proprietà meccaniche die materiali variano da duro e fragile a più morbido, malleabile o gommoso.glass transition because water acts as a plasticizer. For this reason, the moisture content of the material is an essential parameter to be checked and controlled.
An easy and fast way to proceed is to measure the glass transition of polyamide by means of differential scanning calorimetry (DSC) with the NETZSCH DSC 300 Caliris®. Actually, the higher the moisture content, the lower the glass transition temperature, so that this result can be used as a control parameter for the humidity present in the material.
However, the glass transition of polyamide detected in the DSC curves may be overlapped with peaks resulting from RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation effects and water evaporation peak. Temperature-modulated measurements enable separation of the effects for accurate evaluation of the glass transition temperature.
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