Center for Polymers from Renewable Resources

Guangzhou, China

Center for Polymers from Renewable Resources

Guangzhou, China

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Liu X.X.,Center for Polymers from Renewable Resources | Wang Y.F.,Center for Polymers from Renewable Resources | Zhang N.Z.,RMIT University | Shanks R.A.,RMIT University | And 3 more authors.
Chinese Journal of Polymer Science (English Edition) | Year: 2014

Morphology and phase compositions of different starch-gelatin blends were investigated by various microscopes: optical, SEM and synchrotron FTIR microscopy. A high amylose (80%) corn starch, grafted with hydroxypropyl to enhance flexibilty and hydrophilicity, and plasticized by poly(ethylene glycol) (PEG), was used in this work. SEM revealed that the surface became smoother after adding PEG. Optical microscopy observation revealed that compatibility between gelatin and starch was improved by adding PEG. An FTIR beam focused on a 5 μm × 5 μm detection area by the micro-spectroscope was used to map chemical composition. The ratio of areas of the saccharide bands (1180-953 cm-1) and the amide I and II bands (1750-1483 cm-1) was used to monitor the relative distributions of the two components in the blends. The FTIR maps indicated that gelatin constituted the continuous phase up to 80% of starch content. All of the FTIR spectra showed contributions from both starch and gelatin absorptions, therefore indicating that complete demixing with pure starch and gelatin domains did not occur. The PEG improved the compatibility of the gelatin-starch blends. © 2014 Chinese Chemical Society Institute of Chemistry, CAS Springer-Verlag Berlin Heidelberg.


Liu H.,Center for Polymers from Renewable Resources | Yu L.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | Chen L.,Center for Polymers from Renewable Resources
Starch/Staerke | Year: 2010

The retrogradation process of the biphasic endotherms Gr and M1r for waxy cornstarch was systematically investigated using differential scanning calorimetry (DSC). The high temperature endotherm M1r developed significantly within 2-5 h, while the retrograded endotherm Gr appeared after 5 h storage and increased with time. The single endotherm Gr was separated using an analytical software, and the enthalpy was found to be ∼36% of the total enthalpy of the retrograded starch. Compared to normal cornstarch (∼77% amylopectin content), the final retrogradation ratio of the waxy cornstarch was higher. Both the waxy and normal cornstarches investigated showed a similar pattern of retrogradation process, which developed quickly in the initial stage (up to 1 day) and then gradually came to a near-constant value in the second stage (from 1 to 20 days). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu X.,Center for Polymers from Renewable Resources | Ma H.,Center for Polymers from Renewable Resources | Yu L.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | And 2 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2014

Thermal oxidation degradation of high-amylose (80 %) cornstarch has been studied using thermogravimetry analyser coupled to Fourier transform infrared spectroscopy (TG-FTIR). The linear structure of amylose provides a modal material to understand how the starch microstructure affects on the decomposition mechanisms. Kinetics of the thermal oxidation has been studied using different methods. It is found that the thermal oxidation degradation is more complex than thermal degradation, thermal oxidation degradation kinetics of the starch can be interpreted in terms of multi-step degradation mechanism, the activation energies obtain from Flynn-Wall-Ozawa (F-W-O) method and modified Coats-Redfern method are in good agreement. TG-FTIR and FTIR results confirm that the thermal oxidation mechanism of starch is a process containing long chain scission and glowing combustion. © 2013 Akadémiai Kiadó, Budapest, Hungary.


Liu X.,Center for Polymers from Renewable Resources | Wang Y.,Center for Polymers from Renewable Resources | Yu L.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | And 3 more authors.
Starch/Staerke | Year: 2013

The objectives of this paper are to review the thermal degradation and stability of starch and starch-based materials, including both fundamental sciences such as detecting techniques, the effect of amylose/amylopectin content in starches and starches modifications, as well as the effect of different processing environments, such as an open or sealed system, and shearless or shear stress conditions. The decomposition temperature of starches was increased with increasing amylopectin content in an open system. In the open system, the initial water content did not affect the decomposition temperature because all water had evaporated from samples prior to reaching the decomposition temperature. Two decomposition temperatures were observed in the sealed system: the first at lower temperature represents long chain scission; and the second at higher temperature involves decomposition of glucose ring. In the sealed system, the first degradation was increased with increasing amylopectin content. There is no observable difference of the second degradation for the samples containing different amylose/amylopectin ratios. The higher the moisture content is, the lower the second decomposition temperature is detected in the sealed system. Significant shear degradation was observed in amylopectin component of starch, while high amylose starch proved less sensitive to shear stress. The achievements in this area have increased the knowledge of polymer science, in particular to understand the degradation of natural polymers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Chen P.,Center for Polymers from Renewable Resources | Chen P.,Monash University | Chen P.,CSIRO | Chen P.,University of South China | And 8 more authors.
Carbohydrate Polymers | Year: 2011

The internal structures of corn starch granules with different amylose/amylopectin contents were studied using different microscopic techniques. The gelatinization phase transitions of the various starches were investigated by hot-stage confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The influence of the amylose/amylopectin ratio on the internal structures and morphologies could be revealed by these techniques. Sharp growth ring structures could be clearly identified for high-amylopectin starches by CLSM and SEM following acid treatment. CLSM allowed the visualization of cross-sections of starch granules without the need for sectioning techniques that lead to destruction of the microstructure of sample, allowing exploration of the gelatinization mechanism. Three-dimensional images of starch granules during gelatinization could be constructed to further explore phase transition mechanisms. It was found that the granules of waxy maize and normal maize starch subsequently break through at their cavity and channels, when the granules became swollen during gelatinization, whilst the granules of G50 and G80 remain granular and break down to smaller pieces. © 2010 Elsevier Ltd. All rights reserved.


Petinakis E.,CSIRO | Petinakis E.,Monash University | Liu X.,CSIRO | Liu X.,Monash University | And 8 more authors.
Polymer Degradation and Stability | Year: 2010

The effect of hydrophilic fillers (starch and wood-flour) on the degradation and decomposition of poly(lactic acid) (PLA) based materials was investigated. Biodegradation was evaluated by composting under controlled conditions in accordance with AS ISO 14855. Thermal decomposition was studied by thermogravimetry (TGA). Morphological variations during biodegradation were investigated by SEM examination. It was found that biodegradation rates of PLA/starch blends and PLA/wood-flour composites were lower than that of pure cellulose but higher than that of pure PLA. The biodegradation rate was increased from about 60% to 80% when the starch content was increased from 10% to 40% after 80 days. Both starch and wood-flour accelerated thermal decomposition of PLA, and starch exhibited a relatively stronger affect then wood-flour. The decomposition temperature of PLA was decreased about 40 °C when the filler content was increased to 40%. Small polar molecules released during thermal decomposition of starch and wood-flour were attributed to the thermal decomposition behaviours of the PLA based blends and composites and their role is further discussed in this paper. © 2010 Elsevier Ltd. All rights reserved.


Liu X.,Center for Polymers from Renewable Resources | Liu X.,CSIRO | Liu X.,Monash University | Khor S.,CSIRO | And 6 more authors.
Thermochimica Acta | Year: 2010

From a commercial viewpoint, the two most promising methods of producing biodegradable polymer materials are: (i) to blend poly(lactic acid) (PLA) with starch and (ii) to reinforce it with cellulose fibres, since both additives are commercially available and are derived from renewable resources. This paper reports on a study of the effects of starch and wood flour (WF) on the thermal stability of PLA using thermogravimetric analysis (TGA) in a nitrogen atmosphere, and TG-FTIR to investigate the effects of degraded products from the two fillers on the thermal degradation of PLA. Both fillers accelerated decomposition by releasing chemicals, in particular those with polar groups that can act as chain scissors in PLA. The lower decomposition temperature of the starch resulted in lower decomposition temperatures for PLA/starch blends compared to PLA/WF composites. In addition, the smaller particle size of the starch compared to the WF, facilitated greater interfacial contact with the PLA matrix, thus enhancing its function in accelerating decomposition. © 2010 Elsevier B.V.


Lan C.,Center for Polymers from Renewable Resources | Yu L.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | Chen P.,Center for Polymers from Renewable Resources | And 5 more authors.
Macromolecular Materials and Engineering | Year: 2010

A new technique for design and preparation of self-reinforced starch films is introduced. The films were based on a high-amylose corn starch that was chemically modified in different ways. Hydroxypropylation was used to decrease gelatinization temperature and improve processability. The reinforcing component consisted of cross-linked starch granules, where the crosslinking increased granule thermal stability and moisture resistance. Distribution of the cross-linked starch was imaged by CLSM, and the matrix/particle interface was studied by SEM. Modulus and tensile properties of the starch film were increased by about 30 and 20%, respectively, after addition of rigid cross-linked starch particles. A perfect interface between matrix and reinforce agent was obtained. Biodegradable starch-based self-reinforced composites were designed and prepared using a high-amylose corn starch. Modulus and tensile properties of the film increased by 30% after addition of 20 wt.-% rigid cross-linked starch particles with no significant loss in failure strain. CLSM demonstrates a homogeneous distribution of the particles in the matrix. There is no observable change of both particle size and brightness for the cross-linked starch, after distribution in the suspension of hydroxypropylated starch. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhang N.,CSIRO | Zhang N.,RMIT University | Liu X.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | And 4 more authors.
Carbohydrate Polymers | Year: 2013

The well recognized complex issue of compatibility between starch and gelatin was investigated based on their interface and phase composition using synchrotron FTIR micro-spectroscope. A high amylose (80%) corn starch grafted with flexible and hydrophilic hydroxpropyl groups and plasticized by poly(ethylene glycol) (PEG) was used in this work. The FTIR beam focused on a 5 μm × 5 μm detection region and the micro-spectroscope was scanned across the gelatin-starch interface. It was found that there was about a 20 μm thickness layer where gelatin and starch were in co-existence, indicating that gelatin and starch are compatible to a certain degree in this system. The ratio of the areas of the saccharide CO bands (1180-953 cm-1) and the amide I and II bands (1750-1483 cm-1) was used to monitor the relative distributions of the two components of the blends. FTIR 2 and 3-dimensional maps indicated that gelatin constituted the continuous phase up to 80% of starch content. The PEG was homogeneously distributed in both gelatin and starch phases, and blurred the interface between gelatin and starch in the chemical maps, indicating that PEG acted not only as a plasticizer but as a compatibilizer for the gelatin-starch blends. © 2013 Elsevier Ltd. All rights reserved.


Liu X.,Center for Polymers from Renewable Resources | Liu X.,CSIRO | Yu L.,Center for Polymers from Renewable Resources | Yu L.,CSIRO | And 7 more authors.
Journal of Applied Polymer Science | Year: 2013

An investigation into the effects of starch on both, UV photo-oxidative degradation and biodegradation, of HDPE was focused on the interface between HDPE and starch using Synchrotron-FTIR microscope (SFTIR-M) and scanning electronic microscope (SEM). Carbonyl group detection by FTIR was conducted to evaluate the effect of degradation following exposure to UV photo-oxidative degradation. The results showed that the concentration of carbonyl groups on the interface were higher, suggesting the role of starch in accelerating the UV photo-oxidative degradation of HDPE. The interface between HDPE and starch was further observed under SEM to study the morphological changes after UV photo-oxidative degradation and biodegradation. Micro-cracking was observed on the interface between starch and HDPE after UV photo-oxidative degradation. Tensile testing after UV exposure showed that the variation rate of elongation was higher for the samples containing starch. Starch, an easily biodegradable material, can also act as initial source of nutrients for micro-organisms (bacteria, fungi, and algae) in the blend materials thus enhancing their biodegradability. © 2013 Wiley Periodicals, Inc.

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