TY - JOUR
T1 - Properties of injection moulded starch/synthetic polymer blends - IV. Thermal and morphological properties
AU - Mani, Ramaswamy
AU - Bhattacharya, Mrinal
N1 - Funding Information:
The authors would like to acknowledge the financial support of the U.S. Department of Energy (Contract # DE-FG02-96ER12185).
PY - 1998/10
Y1 - 1998/10
N2 - The morphological properties of blends of corn starch and maleated polyolefins are presented in this paper. Four different starches were used: unmodified waxy maize, industrial corn, common corn and a high amylose starch. The concentration of starch in the blends was kept at 70% by weight. Three different synthetic polymers, ethylene-vinyl acetate, low density polyethylene and high density polyethylene were melt blended with the respective starches in a corotating twin screw extruder. A corresponding maleated synthetic polymer was added as a compatibilizer. Differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA), scanning (SEM) and transmission electron (TEM) microscope and optical microscopy (OM) were used to evaluate the phase morphology. DSC studies indicate that starch granules underwent melting with each subsequent processing step. This was also confirmed from the optical photomicrographs where the starch granule size decreased after each subsequent processing step. DMA studies showed that the blends exhibited two distinct glass transitions, one for each component and that the glass transition temperature of starch decreased as the amylose content increased in the starch blends. Microscopy studies indicated that the starch phase became finer as the amylopectin content in the starch increased. For blends containing waxy starch, a co-continuous phase with synthetic polymers was evident.
AB - The morphological properties of blends of corn starch and maleated polyolefins are presented in this paper. Four different starches were used: unmodified waxy maize, industrial corn, common corn and a high amylose starch. The concentration of starch in the blends was kept at 70% by weight. Three different synthetic polymers, ethylene-vinyl acetate, low density polyethylene and high density polyethylene were melt blended with the respective starches in a corotating twin screw extruder. A corresponding maleated synthetic polymer was added as a compatibilizer. Differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA), scanning (SEM) and transmission electron (TEM) microscope and optical microscopy (OM) were used to evaluate the phase morphology. DSC studies indicate that starch granules underwent melting with each subsequent processing step. This was also confirmed from the optical photomicrographs where the starch granule size decreased after each subsequent processing step. DMA studies showed that the blends exhibited two distinct glass transitions, one for each component and that the glass transition temperature of starch decreased as the amylose content increased in the starch blends. Microscopy studies indicated that the starch phase became finer as the amylopectin content in the starch increased. For blends containing waxy starch, a co-continuous phase with synthetic polymers was evident.
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U2 - 10.1016/S0014-3057(97)00275-9
DO - 10.1016/S0014-3057(97)00275-9
M3 - Article
AN - SCOPUS:0001450682
SN - 0014-3057
VL - 34
SP - 1477
EP - 1487
JO - European Polymer Journal
JF - European Polymer Journal
IS - 10
ER -