پديد آورندگان :
Ghanbarzadeh Babak نويسنده , Oromiehie Abdulrasoul نويسنده , Musavi Mohamad نويسنده , Razmi Elhame نويسنده , Mohammadzadeh Milani Jafar نويسنده
چكيده لاتين :
One of the zein film forming methods is thermomoulding by hot press. Pure zein
film is very brittle and plasticizers can improve its mechanical and film making
properties. In this research, polyols (glycerol, sorbitol, and manitol) at three
levels (0.5, 0.7 and 1 g/g of zein resin) were used separately as a plasticizer and for
determining their plasticization effectiveness the rheological and thermal properties of
zein resin samples were studied. Sorbitol and glycerol had good plasticizing effects
and could decrease viscoelastic modulus of zein resin considerably, but manitol was
not as effective as them. Resins containing manitol remained rigid and had unfavorable
chalky appearance. The effects of plasticizers on thermal properties of resin were
investigated by DSC at -100 to 150°C. No crystallization and melting peaks related to
zein resin and plasticizers were observed. Thermograms showed that polyolic plasticizers
and zein resin remained a homogeneous material throughout the cooling and
heating cycles. As well as, at glass transition temperature, there is not any significant
difference among zein resins containing various plasticizers. The Tg of different resins
were at 60 -70°C. This was probably due to similar molecular weight of the selected
polyols. In addition, after initial decreasing of Tg of resin, subsequent increase of plasticizer
levels did not cause considerable reduction in it.
