Comparative thermal analysis study of two biopolymers, starch and cellulose

Fabrication and characterization of oxidized starch-xanthan gum composite nanoparticles with efficient emulsifying properties

This study involved the preparation of nanoparticles by combining oxidized starch (OS) with xanthan gum (XG), and emulsions were prepared from this nanoparticle. The physical and chemical characteristics, as well as the emulsification properties of oxidized starch-xanthan gum composite nanoparticles (OGNP), were analyzed. The findings revealed that the OGNP retained spherical shape after the addition of XG, although their diameter increased from approximately 50-150 to 200-400 nm. Zeta potential decreased with XG content. Moreover, emulsions prepared from OGNP exhibited outstanding thermal stability, also showing enhanced storage stability. In addition, emulsions had different rheological properties at different pH values. The apparent viscosity and shear stress of emulsions under alkaline conditions were lower than that of neutral conditions. NaCl increased the apparent viscosity of OGNP-stabilized emulsions while reducing their thermal stability. The nanoparticles prepared in this study have efficient emulsification properties and can extend the application of OS.

Investigation of critical properties of Cassava (Manihot esculenta) peel and bagasse as starch-rich fibrous agro-industrial wastes for biodegradable food packaging

Cassava peel and bagasse are fibrous, starch-rich agro-industrial wastes, which cause severe environmental impacts upon their disposal. However, these can be raw materials for biodegradable food packaging. In this study, their morphological, chemical, thermal properties, crystalline phases, and chemical compositions were investigated, and potential utilisation as alternative biodegradable food packaging matrices has been assessed. Residual starches in cassava peel and bagasse were morphologically similar with that of commercial cassava starch, whereas potassium (8570 ± 56 mg/kg), and calcium (5300 ± 147 mg/kg) were highly abounded in peel and bagasse respectively. The major crystalline phase, α-amylose dihydrate, for cassava peel (97.1 (2) %) and bagasse (99.0 (3) %) point towards the presence of starch. Calcium and silicon reported to be in crystalline phases respectively, in the forms of quartz and whewellite. These beneficial characteristics suggested the potential valorisation of cassava peel and bagasse with special interest as matrices for biodegradable food packaging.

Eco-Friendly Starch Composite Supramolecular Alginate–Ca2+ Hydrogel as Controlled-Release P Fertilizer with Low Responsiveness to Multiple Environmental Stimuli

Environmentally friendly fertilizers (EFFs) have been developed to improve fertilizer efficiency and minimize adverse environmental impacts, but their release behavior under various environmental conditions has been less explored. Using phosphorus (P) in the form of phosphate as a model nutrient, we present a simple method for preparing EFFs based on incorporating the nutrient into polysaccharide supramolecular hydrogels using Cassava starch in the Ca2+-induced cross-link gelation of alginate. The optimal conditions for creating these starch-regulated phosphate hydrogel beads (s-PHBs) were determined, and their release characteristics were initially evaluated in deionized water and then under various environmental stimuli, including pH, temperature, ionic strength, and water hardness. We found that incorporating a starch composite in s-PHBs at pH = 5 resulted in a rough but rigid surface and improved their physical and thermal stability, compared with phosphate hydrogel beads without starch (PHBs), due to the dense hydrogen bonding-supramolecular networks. Additionally, the s-PHBs showed controlled phosphate-release kinetics, following a parabolic diffusion with reduced initial burst effects. Importantly, the developed s-PHBs exhibited a promising low responsiveness to environmental stimuli for phosphate release even under extreme conditions and when tested in rice field water samples, suggesting their potential as a universally effective option for large-scale agricultural activities and potential value for commercial production.

Investigation of Morphological, Chemical, and Thermal Properties of Biodegradable Food Packaging Films Synthesised by Direct Utilisation of Cassava (Monihot esculanta) Bagasse

The utilisation of edible sources of starch such as corn, wheat, potato, and cassava has become the common approach to develop biodegradable food packaging. However, the future food security issue from the wide application of such edible starch sources has become a major concern. Consequently, exploring non-edible sources of starch for starch-based biodegradable food packaging and their property enhancement have become one of the common research interests. Although there has been a great potentials of synthesising biodegradable food packaging by direct utilisation of agro-industrial waste cassava bagasse, there have been very limited studies on this. In this context, the current study investigated the potential of developing biodegradable food packaging by directly using cassava bagasse as an alternative matrix. Two film-forming mixtures were prepared by incorporating glycerol (30% and 35%), powdered cassava bagasse and water. The films were hot-pressed at 60 °C, 100 °C, and 140 °C temperatures under 0.28 t pressure for 6 min. The best film-forming mixture and temperature combination was further tested with 0.42 t and 0.84 t pressures, followed by analysing their morphology, functional group availability and the thermal stability. Accordingly, application of 35% glycerol, with 100 °C, 0.42 t temperature and pressure, respectively, were found to be promising for film preparation. The absence of starch agglomerates in film surfaces with less defects suggested satisfactory dispersion and compatibility of starch granules and glycerol. The film prepared under 0.42 t exhibited slightly higher thermal stability. Synthesised prototypes of food packaging and the obtained characterisation results demonstrated the high feasibility of direct utilisation of cassava bagasse as an alternative, non-edible matrix to synthesise biodegradable food packaging.

Preparation of graphene-starch composite film and its application in sensor materials

In this work, a composite film was prepared by combining reduced graphene oxide (RGO) and starch nanocrystals (SNC). The results show that SNC can be well dispersed on graphene after mixed with the graphene oxide solutions. SNC had a greater impact on the morphology and microstructure of the composite film. Moreover, the introduction of SNC and the efficient reduction process of graphene oxide (GO) render these composite films good mechanical properties as well as high electrical conductivity. The tensile strength of the composite film was improved after being combined with graphene. However, as the addition rate of SNC increased, the strain-to-failure of the composite film decreased. Therefore, 10% reduced graphene-starch nanocrystals (10%RGO-SNC) was used as multifunctional sensor materials. And it had strong responses to different external stimuli, such as, temperature, humidity, bending/stretching, and solutions.

Integrated Efforts for the Valorization of Sweet Potato By-Products within a Circular Economy Concept: Biocomposites for Packaging Applications Close the Loop

With the aim to fully exploit the by-products obtained after the industrial extraction of starch from sweet potatoes, a cascading approach was developed to extract high-value molecules, such as proteins and pectins, and to valorize the solid fraction, rich in starch and fibrous components. This fraction was used to prepare new biocomposites designed for food packaging applications. The sweet potato residue was added to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in various amounts up to 40 wt % by melt mixing, without any previous treatment. The composites are semicrystalline materials, characterized by thermal stability up to 260 °C. For the composites containing up to 10 wt % of residue, the tensile strength remains over 30 MPa and the strain stays over 3.2%. A homogeneous dispersion of the sweet potato waste into the bio-polymeric matrix was achieved but, despite the presence of hydrogen bond interactions between the components, a poor interfacial adhesion was detected. Considering the significant percentage of sweet potato waste used, the biocomposites obtained show a low economic and environmental impact, resulting in an interesting bio-alternative to the materials commonly used in the packaging industry. Thus, according to the principles of a circular economy, the preparation of the biocomposites closes the loop of the complete valorization of sweet potato products and by-products.

Temperature-insensitive silicone composites as ballistic witness materials: the impact of water content on the thermophysical properties

In this work, different formulations of a room-temperature silicone composite backing material (SCBM) composed of polydimethylsiloxane (PDMS), fumed silica and corn starch were investigated using different characterization techniques, i.e., differential scanning calorimetry, thermogravimetry analysis, X-ray diffraction (XRD) and small-angle X-ray scattering, as a function of controlled relative humidity. At ambient relative humidities in the range of about 20-80%, the equilibrium water content in the SCBM ranges from approximately 4-10%, which is predominantly absorbed by the corn starch. This amount of water content has been shown to have minimal effect on thermal transition temperatures (melting and glass transition) of the SCBMs. The enthalpy of melting increases with increasing relative humidity, which reflects the heterogeneous semicrystalline structure of starch granules and the role of moisture in facilitating the formation of amylopectin double helices mainly in the imperfect crystalline regions. The thermal degradation of SCBM exhibits three major mass loss steps that correspond to dehydration, decomposition of corn starch and decomposition of PDMS. The XRD patterns reveal a characteristic diffuse peak for amorphous PDMS and an A-type crystallinity for the corn starch. The XRD results show no observable changes in the crystal type and crystallinity as a function of moisture content. Results from this work help clarify the fundamental structure-property relationships in SCBMs, which are important for future development of documentary standards, especially the handling and storage specifications of next-generation ballistic witness materials for body armor testing.

Thermal, Mechanical, Viscoelastic and Morphological Properties of Poly(lactic acid) based Biocomposites with Potato Pulp Powder Treated with Waxes

The thermal, mechanical and viscoelastic properties of biocomposites of poly(lactic acid) (PLA) with 20 wt.% of potato pulp powder were investigated. The potato pulp powder utilized is a byproduct from the production and extraction of starch. The results showed that the potato pulp powder does not act as reinforcement, but as filler for PLA, due to an unfavorable aspect ratio and the irregular shape of the particles. In order to improve the mechanical response of the PLA/potato pulp powder biocomposites, surface treatment of the potato pulp particles with bio-based and petroleum-based waxes was investigated. This treatment was found to improve the properties of the biocomposites, enhancing the adhesion between the PLA based polymeric matrix and the potato pulp fibers. The best result is obtained with a petroleum-based wax, but also the bio-based waxes lead to good mechanical properties of the biocomposite. Thus, the addition to PLA of potato pulp powder, treated with waxes, appears a method able to (i) utilize and valorize an abundant agro-food biomass such as potato pulp, according to the principles of circular economy, (ii) favor the production of articles with properties valuable for practical applications, and (iii) reduce the cost of the final products, considering the relatively high cost of PLA.

Thermal and Mechanical Properties of Biocomposites Made of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Potato Pulp Powder

The thermal and mechanical properties of biocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 5 wt % of valerate units, with 20 wt % of potato pulp powder were investigated in order (i) to obtain information on possible miscibility/compatibility between the biopolymers and the potato pulp, and (ii) to quantify how the addition of this filler modifies the properties of the polymeric material. The potato pulp powder utilized is a residue of processing for the production and extraction of starch. The final aim of this study is the preparation of PHBV based materials with reduced cost, thanks to biomass valorization, in agreement with the circular economy policy, as result of the incorporation of agricultural organic waste. The results showed that the potato pulp powder does not act as reinforcement, but rather as filler for the PHBV polymeric matrix. A moderate loss in mechanical properties is detected (decrease in elastic modulus, tensile strength and elongation at break), which regardless still meets the technical requirements indicated for rigid packaging production. In order to improve the mechanical response of the PHBV/potato pulp powder biocomposites, surface treatment of the potato pulp powder with bio-based and petroleum-based waxes was investigated. Good enhancement of the mechanical properties was achieved with the natural carnauba and bee waxes.

Thermal, Mechanical, and Rheological Properties of Biocomposites Made of Poly(lactic acid) and Potato Pulp Powder

The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the possible miscibility and compatibility between PLA and the potato pulp. The potato pulp powder utilized is a residue of the processing for the production and extraction of starch. The study was conducted by analyzing the effect of the potato pulp concentration on the thermal, mechanical, and rheological properties of the biocomposites. The results showed that the potato pulp powder does not act as reinforcement but as filler for the PLA polymeric matrix. A progressive decrease in elastic modulus, tensile strength, and elongation at break was observed with increasing the potato pulp percentage. This moderate loss of mechanical properties, however, still meets the technical requirements indicated for the production of rigid packaging items. The incorporation of potato pulp powder to PLA offers the possibility to reduce the cost of the final products and promotes a circular economy approach for the valorization of agro-food waste biomass.

Determination of the vapour pressure curves and vaporization enthalpies of hafnium alkoxides using thermogravimetric analysis

In order to identify a volatile metallo-organic precursor for the deposition of hafnium oxide (HfO₂) films for atomic layer deposition (ALD) applications, the evaporative properties of hafnium alkoxides (hafnium isopropoxide, hafnium n-propoxide and hafnium n-butoxide) were investigated using thermogravimetric analysis. These hafnium alkoxide samples were synthesized by the electrochemical method and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance and inductively coupled plasma analysis techniques. The characterization results indicated that the products were 99.997% high-purity hafnium alkoxides and could meet the requirement of purity considering the usage of making HfO₂ gate oxide by ALD. Synthesized samples were subjected to a simultaneous thermogravimetric-differential thermal analysis unit at 10 K min^-1 in a dry nitrogen atmosphere flowing at 100 ml min^-1. Benzoic acid was used to calculate a calibration constant, which could then be inserted into a modified Langmuir equation to calculate vapour pressure curves for hafnium isopropoxide and hafnium n-propoxide. Detailed vapour pressure data for the HfO₂ precursor hafnium alkoxides were determined. The vapour pressure curve of hafnium isopropoxide was constructed within the first stage, and calculated to be lnp = 31.157 (±0.200)-13130.57 (±56.50)/T. Hafnium n-propoxide and hafnium n-butoxide were simultaneously undergoing evaporation and decomposition, thus making calculations invalid.

Investigating the thermal decomposition of starch and cellulose in model systems and toasted bread using domino tandem mass spectrometry

Many dietary products containing polysaccharides, mostly starch and cellulose, are processed by thermal treatment. Similarly to the formation of caramel from mono- and disaccharides, the chemical structure of the carbohydrates is dramatically altered by heat treatment. This contribution investigates the products of thermal decomposition of pure starch and cellulose as model systems followed by an investigation of bread obtained at comparable conditions using a combination of modern mass spectrometry techniques. From both starch and cellulose, dehydrated oligomers of glucose and dehydrated glucose have been predominately observed, with oligomers of more than four glucose moieties dominating. Moreover, disproportionation and oligomers with up to six carbohydrates units are formed through unselective glycosidic bond breakage. MALDI-MS data confirm the presence of the majority of products in toasted bread.

Preparation and characterization of activated carbon produced from rice straw by (NH4)2HPO4 activation

Effects of different pretreatment protocols in (NH(4))(2)HPO(4) activation of rice straw on porous activated carbon evolution were evaluated. The pore structure, morphology and surface chemistry of obtained activated carbons were investigated by nitrogen adsorption, scanning electron microscopy and Fourier transform infrared spectroscopy. It was found that pretreatment combining impregnation with (NH(4))(2)HPO(4) and preoxidation could significantly affect the physicochemical properties of prepared activated carbons. The apparent surface area and total pore volume as high as 1154 m(2)/g and 0.670 cm(3)/g were obtained respectively, when combined process of impregnation followed by preoxidation at 200°C and activation at 700°C was carried out. Meanwhile, the activated carbon yield and maximum methylene blue adsorption capacity up to 41.14% and 129.5 mg/g were achieved, respectively. The results exhibited that (NH(4))(2)HPO(4) could be an effective activating agent for producing activated carbons from rice straw.

Thermal stability investigation and the kinetic study of Folnak degradation process under nonisothermal conditions

The nonisothermal degradation process of Folnak drug samples was investigated by simultaneous thermogravimetric and differential thermal analysis in the temperature range from an ambient one up to 810 degrees C. It was established that the degradation proceeds through the five degradation stages (designated as I, II, III, IV, and V), which include: the dehydration (I), the melting process of excipients (II), as well as the decomposition of folic acid (III), corn starch (IV), and saccharose (V), respectively. It was established that the presented excipients show a different behavior from that of the pure materials. During degradation, all excipients increase their thermal stability, and some kind of solid-solid and/or solid-gas interaction occurs. The kinetic parameters and reaction mechanism for the folic acid decomposition were established using different calculation procedures. It was concluded that the folic acid decomposition mechanism cannot be explained by the simple reaction order (ROn) model (n = 1) but with the complex reaction mechanism which includes the higher reaction orders (RO, n > 1), with average value of <n > = 1.91. The isothermal predictions of the third (III) degradation stage of Folnak sample, at four different temperatures (T (iso) = 180 degrees C, 200 degrees C, 220 degrees C, and 260 degrees C), were established. It was concluded that the shapes of the isothermal conversion curves at lower temperatures (180-200 degrees C) were similar, whereas became more complex with further temperature increase due to the pterin and p-amino benzoic acid decomposition behavior, which brings the additional complexity in the overall folic acid decomposition process.

Thermal behavior of corn starch granules modified by acid treatment at 30 and 50°C

Unprocessed native starches are structurally too weak and functionally too restricted for application in today's advanced food technologies. Processing is necessary to engender a range of functionality. Naturals or natives starches can be modified by using several methods physical, chemical, enzymatic or combined, according industrial purposes. In this work, native corn starch was hydrolyzed by hydrochloric acid solution and investigated by using thermoanalytical techniques (thermogravimetry - TG, differential thermal analysis - DTA and differential scanning calorimetry - DSC), as well as optical microscopy and X-ray diffractometry. After acid treatment at 30 and 50°C, a decrease of gelatinization enthalpy (ΔHgel) was verified. Optical microscopy and X-ray diffractometry allowed us to verify the granules contorn and rugosity typical of cereal starches.