New Evidences on the Process Sensitivity of Some Renewable Blends Based on Starch considering Their Melt Rheological Properties

Abstract

The degradability and processability of new renewable materials based on starch and PVOH were studied using the melt flow index (MFI) method by measuring the melt rheological properties which depend not only on the extrusion conditions and material formulation but also on the macromolecule characteristics which can be modified by chemical degradation. These results were correlated with other material properties like color and cross-linking degree. The obtained results show that flowing in the melted state of the studied materials is accompanied by a second process of chains chemical degradation. It was observed that, at the same level of additivation, under identical extrusion conditions, the melted blends with corn starch as main component are highly mechanically sensitive and degrade mostly by chains scission and those with PVOH as major component are highly temperature sensitive and degrade mainly by cross-linking. The obtained results show also that each PVOH-starch blend requires particular formulation and individual windows of melt processing conditions. These results are a good proof that the MFI method is a good path to study the degradability and moldability of process sensitive polymeric materials like those based on starch and PVOH.

Some Aspects Conditioning the Achieving of Filaments for 3D Printing from Physical Modified Corn Starch

“…These diffractograms have proved the advanced miscibility between starch and PVOH as it has been demonstrated already [14]. The novelty is related to the dependency of the compound miscibility on the particles size of the fractions compounded in each situation.…”

“…The samples for mechanical characterization have been obtained through injection (Ray-Ran injection device) in selected conditions (90-170 o C, 5min.-10min.-10min., 200 barr). Because the starch-PVOH compounds with less then 50 % starch are more susceptible at temperature changes [14], only the influence of the injection temperature on the mechanical properties was studied. The 3D printing has been done on a 3D printer-model UP Plus 2.…”

“…Several known studies regarding the starch -PVOH compounds refer to issues as: acquiring methods [11,12], plasticizer types [15][16][17][18][19][20][21][22], parameters influencing functional properties [10,11,13,14], other polymeric modifiers [23,24], nano-composites [25], compatibility [26,28], cross-linking [26,27], starch phase transition [29][30][31][32][33][34]. However, about the possibilities to control both the defects and the undesired color change of starch based materials at melt compounding, only general data, in the best case, are known [35].…”

“…Obviously, considering the already known high degradability of starch [7,15] and of PVOH [36][37][38][39][40], the color change was linked with the degradation during melt compounding. Breaking or/and crosslinking of macromolecules with molecular weight diminishing and double bonds formation responsable for the coloring of the starch based-compounds, is the result of the first stage of mechano-thermo-oxidation during melt compounding [14,15]. Protection against degradation, via stabilization [41][42][43][44][45] at melt processing [41,[43][44][45] and/or for usage [42], as counter-methods, in technological practice is used.…”

STRUCTURAL, MORPHOLOGICAL AND THERMAL ANALYSIS OF SOME ALGINATE/STARCH/DELLITE HPS COMPOSITES FOR AQUEOUS Cu(II) REMOVAL

“…This behavior at swelling can be explained by the hydrophilicity of starch. 31 The linear component (amylose) from the starch structure in contact with water forms networks to hold water molecules. 32 Also, the interaction of reactive -OH groups from n-clays and starch with the reactive sites of alginate resulted in superabsorbent composites.…”