Twin‐screw extrusion production and characterization of starch foam products for use in cushioning and insulation applications

Abstract

Cylindrical starch foam shapes were produced on a small scale (ϳ11-12 kg/hr) Werner Pfleiderer ZSK-30 twin-screw extrusion (TSE) process using water, which functions as a plasticizer as well as a blowing agent. The properties of the starch foams depend on the type of starch used (hydroxypropylated high amylose corn starch, 70% amylose), the amount of water and additives (poly(hydroxyamino ether)) (PHAE) used, and extrusion conditions such as temperature and the screw configuration. PHAE offers the adhesion and durability of epoxy resins with the flexibility and processibility of thermoplastic resins. PHAE was successful in imparting mechanical strength and toughness, cell integrity, weather and water resistance to the foam structure. The purpose of this work was to study the effects of the extrusion (melt) temperature, amount of water added and the screw configuration on the density of starch foams. The water externally added was varied from 3% to 12%, while the PHAE content was varied from 3% to 15% of the starch used (on a wet basis). The foaming was carried out at melt temperatures in the range from 85 to 145°C. A match of material properties with process engineering conditions was achieved to facilitate the control of expansion to a structure with valuable commercial properties. The effects of processing conditions on the foaming process were studied using a Werner Pfleiderer ZSK-30 twin screw extruder. The optimum temperature, blowing agent content, and PHAE content were determined. The density of the cylindrical foam extrudates obtained was 22-25 kg/m 3 . The screw configuration, temperature and pressure profiles, and additives affected the morphology, expansion ratio (ER), resilience, and compressibility of the product. These results were then employed on an industrial scale (410 -420 kg/hr) twin-screw food extruder, a Wenger-80, to manufacture foam sheets. The density of the foam sheets was 27-30 kg/m 3 . The cushioning and insulation proper-ties were studied and are reported. POLYM. ENG. SCI., 46: -451, 2006.

Effect of PVA and PDE on selected structural characteristics of extrusion-cooked starch foams

“…For these reasons several tests as compression, elongation, or bending could be performed for the evaluation of Young modulus, compression stress and strain or breaking resistance. The idea of polymer-starch blends gave the possibility to achieve products undergo dezintegration or degradation without lowering the functional and mechanical properties [3,6,40] .…”

Physical and/or Chemical Modifications of Starch by Thermoplastic Extrusion

“…This is of great interest for polymer processing techniques (such as foaming or film blowing) that require high melt strength. Nabar et al (2006) produced the cylindrical starch foam shapes on a small scale (∼11-12 kg/hr) Werner Pfleiderer ZSK-30 twin-screw extrusion (TSE) process using water, which functions as a plasticizer as well as a blowing agent. The properties of the starch foams depend on the type of starch used (hydroxypropylated high amylose corn starch, 70% amylose), the amount of water and additives (poly(hydroxyamino ether)) (PHAE) used, and extrusion conditions such as temperature and the screw configuration.…”

Analysis of the dynamic behavior of a starch foam extrusion process

“…This specific screw configuration was selected to get the best physicomechanical properties based on our previous work. 25 A cylindrical filament die 2.7 mm in diameter and 8.1 mm in length, with a cooling sleeve, was assembled to the extruder. The sensors were mounted on the die to measure the temperature and pressure of the melt.…”

“…Several researchers have studied the dynamic modeling and control of extrusion processes, based on their gross dynamic input-output behavior. [17][18][19][20][21][22][23][24] In our previous paper, 25 we have reported on the twin-screw extrusion production of starch foams using poly(hydroxy aminoether) (PHAE) as the functional aid, as well as on the optimization of the process. In the present work, the dynamic response of various process variables of a twin-screw extrusion starch foaming process or the sensitivity of the process parameters to the change in inputs were studied, both of which must be known for the implementation of process control.…”