Interrelationships between thermomechanical treatment and macromolecular degradation of maize starch in a novel rheometer with preshearing

Vergnes, Bruno; Villemaire, J. P.; Colonna, Paul; Tayeb, Jean

doi:10.1016/s0733-5210(87)80022-x

Cited by 96 publications

(51 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To calculate the volumetric flow rate, Q, the density of the melt was assumed to be 1.4 g/cm 3 . Similar values have been reported for the density of starch based materials (1.2-1.5 g/cm 3 [245,247,252,261]). Within this range, the sensitivity of the calculated model parameters to density values is negligable.…”

Section: Analysis Of Datasupporting

confidence: 87%

“…Vergnes et al [261] described the thermomechanical energy used to shear the molten material in the extruder as a means of understanding molecular degradation. They found there was a clear relationship between the degree of macromolecular degradation and intensity of treatment.…”

Section: Modelling Rheological Properties Of Starch Extrudatesmentioning

confidence: 99%

“…A number of researchers have used both capillary and slit die rheometry to investigate changes in the melt viscosity with shear rate at several temperatures for both natural and synthetic polymer melts. Single screw extruders [91,241,251,[255][256][257], twin screw extruders [250,[258][259][260][261], and pre-shearing rheometers that can control the extent of thermo-mechanical treatment before viscosity measurements [248,261] have all been used to pump starch-based melts through a die to determine the pressure profile along an axis of flow. Results from these experiments are usually gathered to develop models that predict the viscosity of the extruded starch material as a function of shear rate, temperature and moisture content [232,246,249,254], as well as the time-temperature effects that influence the extent of melting, gelatinisation and fragmentation [244,255,[257][258][259].…”

Section: Slit-die Extrusionmentioning

confidence: 99%

“…Some researchers have attempted to control the amount of thermo-mechanical treatment prior to viscosity measurements in an attempt to acquire data for the one rheological fluid at various shear rates [248,261]. However, controlling the amount of feed into the single screw extruder at constant screw speed as a means of separating the time of thermomechanical treatment and shear rate was not possible to any degree of control with the apparatus used in this study.…”

Section: Analysis Of Datamentioning

confidence: 99%

“…A number of publications note the effect of low moisture content on the molecular degradation of starch during extrusion [224,228,233,236,257,261]. The influence of moisture content on viscosity has been modelled with significant success using an exponential relationship with viscosity, first by Harper et al [254] (Eq.…”

Section: The Effects Of Mechanical Shearmentioning

confidence: 99%

See 4 more Smart Citations

A conceptual model of a sustainable system based upon observations of biodegradable plastic packaging film experiments and material flow

Fletcher¹

View full text Add to dashboard Cite

One can imagine full knowledge of a system allows for optimal decision making when problems arising within that system need to be solved. In reality, solutions involving any non-trivial system must be pursued with incomplete knowledge. In light of the complexity and diversity of current industrial economic systems and the decision-making processes pertaining to them, integrating streams of knowledge would improve problem solving outcomes on such scales. More specifically, it could potentially address how to compare the rate of problem proliferation to solution implementation within a system. However, successfully integrating knowledge of diverse systems towards a common purpose requires careful and consistent analogies to be constructed between the entities of those systems. The current work investigates the merits of such an approach for resolving sustainable development issues. The hypothesis is that knowledge of what influences the flow and transformation of matter, (that is, what influences a common phenomenon throughout life-supporting systems), can facilitate this integration. The problem of accumulating material waste is used as a vehicle to focus the discussion.To this end, the foundation of the work is an experimental study into the development of a starch based biodegradable plastic packaging film. The two main constraints on sample production were to minimise cost and maximise biodegradability. Slit die rheological data is gathered for five samples selected from polymer extrusion trials as part of describing their viscous behaviours via a semi-empirical model incorporating die temperature (measured at 120, 140 and 160°C) and shear rate (altered by screw speeds of 5-50 rpm).The samples differ in additive content and extrusion passes from a baseline starch/water/glycerol (~73/18/9.0 wt% total) combination extruded once to the addition of cross-linking agents and surface modifiers (<1 wt% total) extruded twice. GPC, DSC, tensile strength and moisture absorption analyses join the rheological data to explain The experimental study represents a typical analytical approach to developing a technical solution. Yet while technology will remain indispensable to problem solving, there is a iii need to realise that splintering knowledge into disciplines of the ever finer detail required to extend technical accomplishment, must also be complemented by a synthesis of associated facts and relevant theories to address more encompassing problems associated with sustainability of the modern industrial economy. Therefore, considering the relative success of modelling the viscous behaviour of the starch based plastic samples, it was proposed to extend the concepts of rheology used to explain the flow of matter on the molecular scale to the flow of matter on the scale of the industrial economy.To whatever extent possible, the advantages of being able to predict how such flows respond to industrial economic decisions would contribute to the research of sustainable systems.The assumption is made here that an apt mate...

show abstract

Section: Analysis Of Datasupporting

confidence: 87%

Section: Modelling Rheological Properties Of Starch Extrudatesmentioning

confidence: 99%

Section: Slit-die Extrusionmentioning

confidence: 99%

Section: Analysis Of Datamentioning

confidence: 99%

Section: The Effects Of Mechanical Shearmentioning

confidence: 99%

See 3 more Smart Citations

A conceptual model of a sustainable system based upon observations of biodegradable plastic packaging film experiments and material flow

Fletcher¹

View full text Add to dashboard Cite

show abstract

Effects of Phosphorylating Salts and Temperature on the Preparation of Rice Starch Phosphates by Extrusion

Kim¹,

Shih²,

Champagne³

et al. 1999

Starch/Stärke

View full text Add to dashboard Cite

New Orleans (USA) tion of intermolecular cross-linking caused by the heat and shear of extrusion. Generally, extrusion stabilized the pasting properties of the extrudates, whereas phosphorylation enhanced the pasting consistency of the starch products. Good correlation was observed between the extrusion specific mechanical energy (SME) and the product of solubility and intrinsic viscosity, indicating a close relationship between the energy input in the extrusion process and the performance behavior of the extruded phosphorylation products.

show abstract

Application of an In-line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

Bindzus¹,

Fayard²,

Lengerich³

et al. 2002

Starch/Stärke

View full text Add to dashboard Cite

An in-line viscometer was designed and constructed to enable determination of the shear stress of plasticised wheat starch during extrusion cooking. The viscometer was installed between the end of the barrel section and the extruder die plate so that the shear stress could be determined for the plasticised material, irrespective of the geometrical shape into which it was subsequently moulded by the extruder die. The extrusion conditions were described in terms of the process parameters, i. e. water content, barrel temperature, screw speed and screw configuration; and of the system parameters, which were the specific mechanical energy input (SME), product temperature (PT) and mean residence time (MRT). The parameters were measured and the results evaluated using statistical methods. Regression equations were used to describe functional relationships between the shear stress and the extrusion conditions on the one hand, and between the shear stress and the product characteristics of the extrudates on the other. The shear stress of plasticised wheat starch determined in-line can be used to predict the morphological structure (volumetric expansion) and the functional properties (cold paste viscosity and cold water solubility) of extruded, directly expanded starch with a high degree of accuracy. The measurement technique used and the results of the extrusion tests undertaken for this project will therefore enable the shear stress of plasticised material in an extruder to be used as the principle parameter for controlling extruders on-line.

show abstract

Interrelationships between thermomechanical treatment and macromolecular degradation of maize starch in a novel rheometer with preshearing

Cited by 96 publications

References 13 publications

A conceptual model of a sustainable system based upon observations of biodegradable plastic packaging film experiments and material flow

A conceptual model of a sustainable system based upon observations of biodegradable plastic packaging film experiments and material flow

Effects of Phosphorylating Salts and Temperature on the Preparation of Rice Starch Phosphates by Extrusion

Application of an In-line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

Contact Info

Product

Resources

About