Pva storage modulus

What are the mechanical properties of PVA?

In order to accurately evaluate the mechanical properties of PVA, the real water content is controlled at less than 20 wt%. mechanical performances, Tg, FFV, the relaxation and intermocular H-bonding interactions of PVA are fully examined.

Does water increase tensile strength and elastic modulus of PVA?

Our results show that both tensile strength and elastic modulus of PVA steadily decrease while the strain-at-break increases first and then decreases with increasing water contents (up to 20 wt%). Only 1.8 wt% water can lead to a brittle-ductile transition during tension.

How does water affect the mechanical strength and modulus of PVA chains?

Therefore, the addition of water can disrupt and even destroy the strong H-bonding between PVA chains by replacing such interactions. As a result of the disrupted intermolecular H-bonding, the mechanical strength and modulus of PVA display a gradual decline trend with increasing water contents by the plasticization effect.

How does atomic force microscopy determine the elastic modulus of PVA?

Zhang et al. pioneered to use atomic force microscopy (AFM) to determine the elastic modulus of PVA in water and found that the H-bonding governs the modulus of PVA . Briscoe et al. found that the viscosity of aqueous PVA solutions depend on the H-bonding interactions .

How do water molecules govern the mechanical properties of PVA?

Therefore, water molecules govern the mechanical properties of PVA by disrupting the intermolecular H-bonding interactions and promoting the chain movement of PVA. 4.

How does water affect the mechanical strength of PVA?

The presence of water significantly reduces the mechanical strength of PVA. 1.8 wt% of water reduces tensile strength by ~32% but increases the ductility of PVA by ~2.5 times. The inclusion of water remarkably lowers the glass transition temperature of PVA. The addition of water increases the free volume and promotes the relaxation of PVA chains.