Properties and ageing behaviour of pea starch films as affected by blend with poly(vinyl alcohol)

• Pea Starch (S) and PVA blend films presented a certain degree of compatibility.
• The ageing of pea starch films was inhibited by PVA.
• PVA recrystallization was limited in 1:1 S:PVA blend films.
• Mechanical and water barrier properties were enhanced in 1:1 and 1:2 S:PVA blend films.

Pea starch (S) and poly(vinyl alcohol) (PVA) blends with different ratios were produced in order to elucidate the possible advantages of blend films to overcome the common drawbacks of starch films. Starch, poly(vinyl alcohol) and blends (S:PVA ratios of 2:1, 1:1 and 1:2) were obtained by casting and microstructure and thermal behaviour were characterized. Moreover, barrier, mechanical and optical properties were evaluated after 1 and 5 storage weeks at 25 °C and 53% relative humidity in order to study the effect of poly(vinyl alcohol) on the ageing process of starch. The incorporation of PVA into pea starch films implied the formation of interpenetrated networks of both incompatible polymers with partial solubilisation. S-PVA blend films were much more extensible and stable during storage, with improved water barrier properties and reduced water sorption capacity especially when the S:PVA ratio were 1:1 and 1:2. Starch-poly(vinyl alcohol) blend films are environmentally friendly, low cost materials, with good functional properties.

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