Rangrong Yoksan and Amporn Sane and Nattaporn Khanoonkon and Chanakorn Yokesahachart and Narumol Noivoil and Khanh Minh Dang
Effect of Starch and Plasticizer Types and Fiber Content on Properties of Polylactic AcidThermoplastic Starch Blend
1166 - 1170
2015
9
9
International Journal of Materials and Metallurgical Engineering
https://publications.waset.org/pdf/10002740
https://publications.waset.org/vol/105
World Academy of Science, Engineering and Technology
Polylactic acid (PLA) is the most commercially
available biobased and biodegradable plastic at present. PLA has
been used in plastic related industries including singleused
containers, disposable and environmentally friendly packaging owing
to its renewability, compostability, biodegradability, and safety.
Although PLA demonstrates reasonably good optical, physical,
mechanical and barrier properties comparable to the existing
petroleumbased plastics, its brittleness and mold shrinkage as well as
its price are the points to be concerned for the production of rigid and
semirigid packaging. Blending PLA with other biobased polymers
including thermoplastic starch (TPS) is an alternative not only to
achieve a complete biobased plastic, but also to reduce the
brittleness, shrinkage during molding and production cost of the
PLAbased products. TPS is a material produced mainly from starch
which is cheap, renewable, biodegradable, compostable, and nontoxic.
It is commonly prepared by a plasticization of starch under
applying heat and shear force. Although glycerol has been reported as
one of the most plasticizers used for preparing TPS, its migration
caused the surface stickiness of the TPS products. In some cases,
mixed plasticizers or natural fibers have been applied to impede the
retrogradation of starch or reduce the migration of glycerol. The
introduction of fibers into TPSbased materials could reinforce the
polymer matrix as well. Therefore, the objective of the present
research is to study the effect of starch type (i.e. native starch and
phosphate starch), plasticizer type (i.e. glycerol and xylitol with a
weight ratio of glycerol to xylitol of 1000, 7525, 5050, 2575 and
0100) and fiber content (i.e. in the range of 125 wt) on properties
of PLATPS blend and composite. PLATPS blends and composites
were prepared using a twinscrew extruder and then converted into
dumbbellshaped specimens using an injection molding machine. The
PLATPS blends prepared by using phosphate starch showed higher
tensile strength and stiffness than the blends prepared by using native
one. In contrast, the blends from native starch exhibited higher
extensibility and heat distortion temperature (HDT) than those from
the modified starch. Increasing xylitol content resulted in enhanced
tensile strength, stiffness and water resistance, but decreased
extensibility and HDT of the PLATPS blend. Tensile properties and
hydrophobicity of the blend could be improved by incorporating
silane treatedjute fibers.
Open Science Index 105, 2015