Aging properties of extruded high-amylose starch

Shogren, Randal L.; Jasberg, B. K.

doi:10.1007/bf02074778

Cited by 65 publications

(47 citation statements)

References 16 publications

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“…X-ray diffraction patterns of samples 1 and 3N are shown in Figure 3. The significant diffraction maximum at 19.4° and a weaker maximum at 12.7° in both samples indicate the presence of residual structure of the V form of starch [13,18,32]. The absence of the B structure indicates that the native structure in the starch granule was destroyed during foam formation.…”

Section: Flexural Propertiesmentioning

confidence: 91%

“…The absence of the B structure indicates that the native structure in the starch granule was destroyed during foam formation. Some of the amylose probably recrystallized into the V form during the cooling [32]. Figure 4 shows the heating curves of the five samples described in Table 1.…”

Section: Flexural Propertiesmentioning

confidence: 99%

“…The integrated area, including both features and averaged over four specimens, corresponds to ΔH = 2.0±0.1 J/g of dry starch. DSC features observed with starch samples depend on water content, age, source plant, and sample history [32][33][34]. For our purposes, the thermal features in the starch foam ( Figure 4, curve 1) need only be taken to indicate that heat treatment of starch during foam formation leaves some residual starch structure [32].…”

Section: Flexural Propertiesmentioning

confidence: 99%

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Starch-lignin foams

Stevens¹,

Klamczynski²,

Glenn³

2010

Express Polym. Lett.

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Abstract. Although starch foams are well known as biodegradable alternatives to foamed polystyrene, starch-lignin foams have not previously been reported. Lignin is an abundant byproduct of paper manufacture usually burned as fuel for lack of higher-value uses. We have prepared novel starch-kraft lignin foams with a known technique similar to compression molding. Replacing 20% of the starch with lignin has no deleterious effect on density or morphology as indicated by scanning electron microscopy: a thin outer layer of approximately 100 μm encloses a region of cellular structure containing 100-200 μm voids, with the major internal region of the foam consisting of large voids of up to 1 mm in size. Powder X-ray diffraction shows residual structure in both starch and starch-lignin foams. Differential scanning calorimetry displays endothermic transitions in the starch foam but not in the starch-lignin foam, indicating that lignin stabilizes the residual starch structure. Lignin decreases water absorption; diffusion constants for the starch and starch-lignin foams are 2.68·10 -6 and 0.80·10 -6 cm 2 /sec, respectively. The flexural strength of the starch-lignin foam is similar to that of foamed polystyrene, the strain at maximum stress is smaller, and the modulus of elasticity is larger.

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Section: Flexural Propertiesmentioning

confidence: 91%

Section: Flexural Propertiesmentioning

confidence: 99%

Section: Flexural Propertiesmentioning

confidence: 99%

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Starch-lignin foams

Stevens¹,

Klamczynski²,

Glenn³

2010

Express Polym. Lett.

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“…This Glycerol containing starch plastics were shown to leads to differences in water content and to differrecrystallize into various crystal structures deences in properties such as crystallization behavpending on processing as well as storage condiior. [8][9][10][11][12][13] Various articles have been published in tions. 8 Amylose was shown to crystallize into the field of structure-property relationships of several single helical crystal structures and the starch-polymer blends or composites.…”

Section: Introductionmentioning

confidence: 99%

Influence of glycerol and water content on the structure and properties of extruded starch plastic sheets during aging

Soest

Knooren

1997

J. Appl. Polym. Sci.

229

115

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ABSTRACT:The properties of starch plastic sheets were investigated by stress-strain measurements in relation with starch crystallinity. Granular potato starch was plasticized with different amounts of glycerol and water by extrusion. The materials were amorphous directly after processing. During aging above the glass transition temperature at various humidities single helical (V and E-type) and double helical (B-type) crystallinity was formed. The rate of crystallization is a function of water and glycerol content. The amorphous rubbery materials were soft and weak with high elongations. During aging the materials became less flexible with higher elastic modulus and tensile stress. The changes are related to changes in water content and glass transition temperature and to changes in B-type crystallinity. The changes in stress-strain properties are explained by the formation of helical structures and crystals, which results in a reinforcement of the starch network by physical crosslinking.

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“…Although extrusion improves TPS processing by making the product properties more consistent and broadening the application areas, it is still difficult to process high amylose content starches by extrusion. Die pressure will be much higher due to the higher melt viscosity of TPS (Shogren and Jasberg, 1994). In addition, the instability of melt flow is one of the main factors contributing to processing difficulties (Thuwall et al, 2006.…”

Section: Tps Processingmentioning

confidence: 99%

Highly functional green materials platform: Starch-ionic liquid-carbon nanotube polymer melt nanocomposites

Liu¹

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Starch is a promising biodegradable polymer material which has attracted attention recently. A renewable and biodegradable resource can potentially address the shortage of conventional petroleum-based polymers and help solve the problem of environmental pollution from the use of these polymers. To use starch in polymer processing, gelatinisation, which is the process to disrupt the native starch structure, must happen to turn the starch in to an amorphous thermoplastic starch (TPS). However, water, the conventional gelatinisation agent and plasticiser, is extremely volatile and will evaporate during thermal processing. This leads to high melt viscosities, processing difficulties and hence poor product quality. In addition the mechanical properties of the resulting TPS products are not as high as that of the currently used petroleum-based polymers that they seek to replace.Therefore, potential solutions for TPS processing and application development is to use other plasticisers to aid processing and/or to reinforce TPS with nano-particles. One of the key tasks of this project was to understand the plasticizing effects of ionic liquids (ILs) in TPS processing and interpreting these in terms of the molecular interactions between the components. In addition the role of adding nano-particles, in the form of carbon nanotubes, in an attempt to strengthen TPS was investigated. The ultimate aim was to provide design guidelines to produce high value added biodegradable nanocomposites.Three types of ionic liquids (ILs) were considered: 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), 1-allyl-3-methylimidazolium chloride ([Amim]Cl) and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). They were processed in batches of 150g by thermal mixing. Their behaviours were compared to glycerol as plasticisers of TPS, and their effects on TPS processing, water uptake during conditioning, mechanical properties, thermal stabilities, crystallisation behaviour and molecular interaction were studied. Both spectroscopic and X-ray analysis techniques were used to investigate the interactions that occurred, and these were related to the material characteristics. Then, multi-walled carbon nanotubes (MWCNTs) were introduced to the TPS matrix to investigate their behaviour as a strengthening agent and also to potentially create a functional material with useful electrical properties.The results demonstrated that the ILs were effective plasticisers for TPS. However, whilst their use improved the flexibility of TPS, mechanical strength and thermal stability were decreased.The molecular interactions between TPS and ILs were found to differ between TPS and glycerol. This led to differences in the crystalline structures formed, 2% to 4% more water Page | iii uptake during conditioning and hence up to a 90% decrease in Young's modulus. In particular the effect of water uptake during conditioning was identified as the key contributor to the ultimate mechanical properties. The IL plasticised TPS were also found to be less thermally stable.In or...

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Aging properties of extruded high-amylose starch

Cited by 65 publications

References 16 publications

Starch-lignin foams

Starch-lignin foams

Influence of glycerol and water content on the structure and properties of extruded starch plastic sheets during aging

Highly functional green materials platform: Starch-ionic liquid-carbon nanotube polymer melt nanocomposites

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