Plasticized Starch Research Articles

Flexible, thermal processable, self-healing, and fully bio-based starch plastics by constructing dynamic imine network

The serious environmental threat caused by petroleum-based plastics has spurred more researches in developing substitutes from renewable sources. Starch is desirable for fabricating bioplastic due to its abundance and renewable nature. However, limitations such as brittleness, hydrophilicity, and thermal properties restrict its widespread application. To overcome these issues, covalent adaptable network was constructed to fabricate a fully bio-based starch plastic with multiple advantages via Schiff base reactions. This strategy endowed starch plastic with excellent thermal processability, as evidenced by a low glass transition temperature (Tg = 20.15 °C). Through introducing Priamine with long carbon chains, the starch plastic demonstrated superior flexibility (elongation at break = 45.2%) and waterproof capability (water contact angle = 109.2°). Besides, it possessed a good thermal stability and self-adaptability, as well as solvent resistance and chemical degradability. This work provides a promising method to fabricate fully bio-based plastics as alternative to petroleum-based plastics.

The Re-/Up-Cycling of Wood Waste in Wood-Polymer Composites (WPCs) for Common Applications.

Wood-polymer composites (WPCs) are a class of materials intensively studied and promoted in the context of sustainable development, mainly when aspects related to the increasing awareness of environmental issues and waste management are considered. Feasible opportunities for producing WPCs with value-added properties intended for common applications emerge when polymers, either synthetic or from renewable resources, raw or waste, are employed in re-/up-cycling approaches. In this context, some examples of easily achievable WPCs are presented herein, namely, formulations based on different wood waste and polymer matrices (synthetic: polypropylene and malleated polypropylene as a compatibilizer; natural: plasticized starch). Their level of performance was assessed through different characterization methods (FTIR, WAXD, TGA, DSC, mechanical test, etc.). The benefits and limitations of this approach are also discussed.

Effective reinforcement of plasticized starch by the incorporation of graphene, graphene oxide and reduced graphene oxide

Plasticized starch (PLS) nanocomposite films using glycerol and reinforced with graphene (G) and graphene oxide (GO) were prepared by solvent casting procedure. On one hand, the influence of adding different G contents into the PLS matrix was analyzed. In order to improve the stability of G nanoflakes in water, Salvia extracts were added as surfactants. The resulting nanocomposites presented improved mechanical properties. A maximum increase of 287 % in Young's modulus and 57 % in tensile strength was achieved for nanocomposites with 5 wt% of G. However, it seemed that Salvia acted as co-plasticizer for the PLS. Moreover, the addition of the highest G content led to an improvement of the electrical conductivity close to 5 × 10−6 S/m compared to the matrix.On the other hand, GO was also incorporated as nanofiller to prepare nanocomposites. Thus, the effect of increasing the GO content in the final behavior of the PLS nanocomposites was evaluated. The characterization of GO containing PLS nanocomposites showed that strong starch/GO interactions and a good dispersion of the nanofiller were achieved. Moreover, the acidic treatment applied for the reduction of the GO was found to be effective, since the electrical conductivity was 150 times bigger than its G containing counterpart.

A Review on Reinforcements and Additives in Starch-Based Composites for Food Packaging.

The research of starch as a matrix material for manufacturing biodegradable films has been gaining popularity in recent years, indicating its potential and possible limitations. To compete with conventional petroleum-based plastics, an enhancement of their low resistance to water and limited mechanical properties is essential. This review aims to discuss the various types of nanofillers and additives that have been used in plasticized starch films including nanoclays (montmorillonite, halloysite, kaolinite, etc.), poly-saccharide nanofillers (cellulose, starch, chitin, and chitosan nanomaterials), metal oxides (titanium dioxide, zinc oxide, zirconium oxide, etc.), and essential oils (carvacrol, eugenol, cinnamic acid). These reinforcements are frequently used to enhance several physical characteristics including mechanical properties, thermal stability, moisture resistance, oxygen barrier capabilities, and biodegradation rate, providing antimicrobial and antioxidant properties. This paper will provide an overview of the development of starch-based nanocomposite films and coatings applied in food packaging systems through the application of reinforcements and additives.

Synthesis and Characterization of Eco-friendly, Biodegradable Plasticized Starch Nanocomposite using Graphene Oxide Nano-filler for Energy Storage Applications

In this study, environment-friendly, biodegradable nanocomposite has been fabricated using plasticized starch (PS) polymer and graphene oxide (GO) nanofiller. Biodegradable PS has been extracted from potatoes and a solution casting technique was used to synthesize PS/GO nanocomposite. The structural and surface morphological properties of the nanocomposite have been studied via FTIR and FESEM which demonstrate increased degree of interaction between the PS matrix and the GO nanofiller. The thermal properties of the nanocomposite showed that incorporation of GO improves the thermal stability of the nanocomposites. To study the energy storage capabilities of the PS/GO nanocomposites the electrochemical properties of the nanocomposites were as studied through cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) methods. The PS/GO nanocomposite showed improved capacitive performance with a specific capacitance of 112 F/g compared to that of pure starch (2.20 F/g) at a current density 0.1 mA/cm2. To study the effect of GO on the electrochemical properties of the nanocomposites, electrochemical impedance spectroscopy was performed and the corresponding graphs were simulated using simulation software. The incorporation of GO reduces the charge transfer resistance and thereby improve the capacitive performance. The improved electrochemical performance of the PS/GO nanocomposite can be further attributed to the large surface areas provided by the GO sheets allowing faster transport of electrolyte ions into the electrode. The result indicates that the PS/GO and nanocomposites may offer a promising route for the synthesis of bio-friendly and flexible energy storage devices.
 J. of Sci. and Tech. Res. 4(1): 145-154, 2022

The influence of the substitution degree and length of alkyl chains on the sizing properties of alkylation starches

In this work, a series of alkylation starches (St-C n) with different alkylation degrees was synthesized by introducing alkyl chains (the number of carbon atoms was 3, 8, and 12, respectively) onto starch. The influence of the substitution degree ( DS) and length of the alkyl chains on the sizing properties of alkylation starches was studied. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectra provided evidence for the linkage of alkyl chains onto the starch structure. Benefiting from the flexibility characteristic of the alkyl chain and the weakening hydrogen bonding to starch structure, St-C8 alkylation starch film with a DS of 0.114 exhibited a high elongation break of 4.64%, which is higher than that of the modified starches reported in most of the literature. Moreover, the alkyl chain could reduce the internal stress of the starch adhesive layer among fibers, which improved the adhesion of alkylation starch to cotton fibers. The St-C12 alkylation starch obtained by the longer alkyl chain weakened the adhesion among fibers due to the strong hydrophobic effect. This work provides a new idea to achieve starch plasticization.

Evaluation of starch plasticization efficiency by deep eutectic solvents based on choline chloride

The evaluation of potato starch plasticization efficiency with two deep eutectic solvents (DESs), based on choline chloride (CC) and glycerol (G) or urea (U) has been performed. The optical microscopy allowed to observe that both DES exhibited some solubility towards starch, however, the solvent power of CCU was significantly higher than CCG. The XRD result revealed that both tested systems showed the ability to penetrate the starch crystal regions. Moreover, both DESs could form stable hydrogen bonds with hydroxylic groups of the polysaccharide. The viscosity of tested systems depended on starch content (decreased with DES amount), and temperature. The thermal stability of starch material decreased with DES content. The type of DES strongly affected gelatinization temperature (rheology curves), i.e. in CCU it occurred at the temperature below 90 °C, in comparison to CCG - above 110 °C. The plasticization efficiency was tested using the modulated DSC technique. The CCG system exhibited higher plasticizing efficiency, as its lower dosage allowed for a more significant Tg reduction than observed for the system containing CCU. Thus, it could be concluded that although CCG was a poor solvent, was a good plasticizer.

High-performance thermoplastic starch/poly(butylene adipate-co-terephthalate) blends through synergistic plasticization of epoxidized soybean oil and glycerol

Utilizing starch, an abundant polysaccharide, as the renewable filler to blend with poly(butylene adipate-co-terephthalate) (PBAT) is a feasible tactic to construct cost-effective and high-performance biodegradable materials. It's worth noting that the thermal processing properties of starch can be manipulated by its plasticized behavior. Herein, epoxidized soybean oil (ESO) and glycerol were used as the plasticizer for native corn starch and the plasticized starch was integrated with PBAT to manufacture starch-based biodegradable blend films. ESO breaks the hydrogen bonds between starch chains through the fatty chains grafting reaction and increases the distance between starch molecular chains due to the large molecular weight of ESO. Meanwhile, glycerol molecules are incorporated into the starch molecular chains, and fatty chains grafted starch chains, effectively reducing the intermolecular forces of molecular chains. On account of the synergistic plasticization of ESO and glycerol which possess good compatibility with PBAT, the PSG20E10 blend film achieved a tensile strength, an elongation at break of 16.11 MPa and 612.09 %, and the balanced water and oxygen permeability properties.

Exploring the influence mechanism of water grinding on the gel properties of corn starch based on changes in its structure and properties.

At present, most studies have focused on the preparation of modified starches by dry grinding. As an excellent starch plasticizer, water might enhance the action of grinding on the structure of starch granules, and water grinding might improve the gel properties of starch. Therefore, this article explored the influence mechanism of water grinding on the gel properties of corn starch based on the changes in its structure and properties. The results showed that water grinding could make water enter the starch granules and hydrate the starch molecules, and the starch gelatinized after water grinding for 20 min. Thus, water enhanced the action of grinding on the structure of the starch granules. Under the plasticization and grinding action of water grinding, the mechanochemical effect of the starch granules occurred. When the starch was in the aggregation stage (7.5-10 min), the crystallinity of the starch increased, and the starch molecules rearranged into a more stable structure, which increased apparent viscosity (η), elastic modulus (G') and viscous modulus (G″) of the starch gels. Therefore, appropriate water grinding (10 min) contributed to increasing the viscoelasticity of starch gels. This study provided a theoretical foundation for research on improving the properties of starch by mechanical modification in future. © 2023 Society of Chemical Industry.

Insights into solid phase denitrification in wastewater tertiary treatment: the role of solid carbon source in carbon biodegradation and heterotrophic denitrification

The practical application of solid phase denitrification (SPD) was hindered by either poor water quality from natural plant-like materials or high cost of pure synthetic biodegradable polymers. In this study, by combining polycaprolactone (PCL) with new natural materials (peanut shell, sugarcane bagasse), two novel economical solid carbon sources (SCSs) named as PCL/PS and PCL/SB were developed. Pure PCL and PCL/TPS (PCL with thermal plastic starch) were supplied as controls. During the 162-day operation, especially in the shortest HRT (2 h), higher NO3−-N removal was achieved by PCL/PS (87.60%±0.06%) and PCL/SB (87.93%±0.05%) compared to PCL (83.28%±0.07%) and PCL/TPS (81.83%±0.05%). The predicted abundance of functional enzymes revealed the potential metabolism pathways of major components of SCSs. The natural components entered the glycolytic cycle by enzymatical generation of intermediates, while biopolymers being converted into small molecule products under specific enzyme activities (i.e., carboxylesterase, aldehyde dehydrogenase), together providing electrons and energy for denitrification.

Electroactive trilayer actuators taking advantage of the ionic conductivity and self-adhesion of ionic liquid plasticized starch

Ionic liquid (IL) plasticized potato starch and pure amylose films are used as Ionically Conductive Polymers (ICP) for manufacturing electroactive polymer trilayer films able to change of shape upon electrical stimulus, and to work as motion sensors. This promising alternative to fossil fuel based ICPs takes advantage of the water solubility of the starch/IL mixture and its stickiness after casting as films, allowing the design of a solvent free, origami inspired process for its assembly with PEDOT:PSS electrodes.Electroactive free bending motions with an amplitude of deformation Δε of 0.45% are observed upon ± 2 V electrical stimulus for all EAPs, with a 7-fold higher blocking force for the pure amylose based system making it able to lift more than 180 times its weight.Conversely, when tested as sensors, a 4-fold higher sensitivity is observed for the potato starch based EAP, which was comparable to that of fossil-fuel based polymers systems.

FILM-FORMING AND DESTRUCTION POWERS OF COMPOSITIONS BASED ON MODIFICATIONS OF NATURAL POLYMERS

On the basis of the conducted literature review of biodegradable film-forming compositions using modified natural polymers, using the example of starch, it can be seen that the range of possibilities for its modification and the choice of suitable synthetic polymers depend on the method of production and the field of use, and are generaily aimed at protecting the environment. The physico-mechanical and structural characteristics of film-forming polymers polybutyrate PBAT and polycaprolactone PCL, which belong to biodegradable polymers processed by the extrusion method with the addition of thermoplastic starch, were studied. The destructive properties of film-forming compositions obtained from aqueous solutions of plasticized starch after UV irradiation for 90 days were studied. The maximum loss of strength reaches 86%, and the loss of elasticity is 93%.The structural changes of the compositions were investigated by the mass spectrometric method.

Physico-Chemical, Rheological, and Viscoelastic Properties of Starch Bio-Based Materials

This study describes the elaboration and characterization of plasticized starch composites based on lignocellulosic fibers. The transformation of native to plasticized starch (TPS) and the preparation of TPS blends were performed with a new lab-scale mixer based on an original concept. Firstly, the morphology and chemical composition of flax shives were analyzed to better understand the intrinsic properties of these natural fillers. Then, the impact of the processing parameters (temperature, speed screw) on the quality and the structural properties of plasticized starch were examined by SEM and DRX. After that, we focused on the elaboration of various formulations based on plasticized starch matrix by varying TPS formulation and filler content (from 10 to 30%). The viscoelastic and rheological properties of TPS/flax blends have been analyzed by TGA, SEM, and DMTA.

Degradation Rates and Bacterial Community Compositions Vary among Commonly Used Bioplastic Materials in a Brackish Marine Environment.

Plastic pollution threatens both terrestrial and aquatic ecosystems. As a result of the pressures of replacing oil-based materials and reducing the accumulation of litter in the environment, the use of bioplastics is increasing, despite little being known about their accurate biodegradation in natural conditions. Here, we investigated the weight attrition and degradation behavior of four different bioplastic materials compared to conventional oil-based polyethylene during a 1-year in situ incubation in the brackish Baltic Sea and in controlled 1 month biodegradation experiments in the laboratory. Bacterial communities were also investigated to verify whether putative plastic-degrading bacteria are enriched on bioplastics. Poly-l-lactic acid showed no signs of degradation, whereas poly(3-hydroxybutyrate/3-hydroxyvalerate) (PHB/HV), plasticized starch (PR), and cellulose acetate (CA) degraded completely or almost completely during 1-year in situ incubations. In accordance, bacterial taxa potentially capable of using complex carbon substrates and belonging, e.g., to class Gammaproteobacteria were significantly enriched on PHB/HV, PR, and CA. An increase in gammaproteobacterial abundance was also observed in the biodegradation experiments. The results show substantial differences in the persistence and biodegradation rates among bioplastics, thus highlighting the need for carefully selecting materials for applications with risk of becoming marine litter.

Synthesis and characterization of biocomposites based polypropylene/thermoplastic starch- reinforced with natural STIPA TENACISSIMA fibers and PP-g-MA

The current work aims to develop environmentally friendly plastic materials by preparing a composite polypropylene/thermoplastic starch (PP/TPS) using a melt-compounding process. In order to improve the compatibility of the two naturally incompatible polymers, natural Stipa tenacissima fibers treated on their surfaces and polypropylene (PP) pellets grafted with Maleic Anhydride (MA) were added to the mixture (PP and TPS). The mixture was then prepared using the melt-mixing method in various concentrations. X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA)/Differential thermal analysis (DTA), and mechanical tensile tests were then used to characterize the various formulations. SEM images revealed that the addition of (PP-g-MA) and natural fibers resulted in good starch plasticization and higher thermoplastic starch dispersion in the polypropylene matrix. It was also discovered that increasing the TPS concentration over the PP concentration tends to reduce the mechanical tensile properties. However, the composite with 15% TPS had the best mechanical properties. The thermogravimetric analysis (TGA) results revealed that the organic filler used acted as a reinforcing agent, increasing the thermal stability of the polypropylene/thermoplastic starch (PP/TPS) compound.

Starch plasticization with choline dihydrogencitrate-based deep eutectic system

Abstract Two-component deep eutectic solvents (DES) based on choline dihydrogencitrate and glycerol or urea were tested as starch plasticizers. Thermal analysis techniques were applied to characterize the properties of starch/DES systems. The X-ray diffractometry measurements revealed a significant decrease in crystallinity indicating that used DES exhibited the ability to penetrate the ordered regions of potato starch, which is a necessary feature of a true plasticizer. However, the differential scanning calorimetry and dynamic thermal analysis results surprisingly showed an increase of Tg of starch materials indicating chemical crosslinking at elevated temperature. The eutectic solvents based on choline dihydrogencitrate could act as a plasticizer and a simultaneously crosslinking agent.

Biodegradable packaging materials based on low density polyethylene, starch and monoglycerides

Objectives. To investigate the production and biological degradation of biodegradable hybrid compositions (BHCs), dispersed-filled with starch-containing products of various origins and distilled monoglycerides, along with the biodegradation of compositions based on low density polyethylene and thermoplastic starch (TPS) of various origins: corn, pea, and rice.Methods. Thermoplastic starch was obtained based on native starches of several types, which were processed in Brabender and MashkPlast (Russia) laboratory extruders. BHCs in the form of strands, granules, and films were obtained by mixing thermoplastic starches with polyethylene in extruders. Structural BHC parameters were studied by optical and electron scanning microscopy. The biodegradability of the composite films was evaluated by placing them in biohumus for six months; during storage, the change in water absorption of the films was determined. Before and after the biodegradation process, tensile fracture stress and elongation at rupture were determined to evaluate BHC performance (physical and mechanical characteristics of films). Changes in the chemical structure during biodegradation were determined by Fourier infrared spectroscopy.Results. The positive effect (acceleration of the biodegradation process) of using a novel type of starch plasticizer—monoglycerides distilled in TPS–polyethylene compositions—was confirmed. After six months, intensive sporulation of active microorganisms was observed on the surface of the samples. At the same time, water absorption by the samples reached 30%. The observed 60% decrease in strength and deformation properties indicates an intensive process of biodegradation.Conclusions. The biodegradation rate was shown to depend on the concentration and even distribution of the natural biodegradable filler in the synthetic polymer composition.

​Effect of Cassava Starch on LDPE as Biodegradable Film and its Physical and Mechanical Properties

Background: Biodegradable plastics are made from starch extracted from renewable biomass. Approximately 50% of the biodegradable plastics used commercially are prepared from starch. The research was undertaken to develop biodegradable film from blend of LDPE and Cassava starch at different proportions and to study the Physical and Mechanical properties. Methods: Biodegradable film was prepared by Blown film extrusion method using LDPE, cassava starch adding glycerol, talc powder and urea (T0, T1, T2, T3 and T4) at different proportions. The effects of plasticizer (glycerol) and different proportions of cassava starch on the film properties were determined by the standard methods. Result: The developed biodegradable film had a tensile strength ranging from 6.68-8.42 MPa. The film thickness from 0.17 to 0.80 mm, transparency from 0.55 to 2.07%, water absorption from 0.007 to 0.067% and moisture permeability from 0.59 to 14.08%.

Biocomposites from Thermoplastic Postindustrial Waste Starches Filled with Mineral Fillers for Single‐Use Flexible Packaging

AbstractPlasticized starch (PS) materials hold a fundamental role in the design of novel biodegradable and compostable plastics aimed to reduce global single‐use plastic wastes. This work exemplifies the plasticization of postindustrial waste wheat starch (pWWS) and postindustrial corn starch (pWCS) with a comparison to food‐grade corn starch (pCS) by introducing technical waste glycerol (25%) along with urea (5%) and water. The PS (30%) is blended with 70% poly(butylene adipate‐co‐terephthalate) (PBAT) to design a matrix with optimized mechanical properties. As a result, the inclusion of pWCS and pCS shows similar impact strength and melt flow index (MFI) values. Further, the mineral fillers, i.e., talc and calcium carbonate (CaCO3) (25%), are introduced into the PBAT/PS (70%/30%) matrix to explore the effect on MFI, mechanical, thermal, and morphological properties. Scanning electron microscopy analysis reveals good dispersion of PS particles and mineral fillers into the PBAT. Adding talc into the PBAT/pWWS and PBAT/pCS blends shows significantly higher modulus (≈134% and ≈105%, respectively) and heat deflection temperature (HDT) (7.8% and 9.3%, respectively). The addition of 25% CaCO3 results in the impact strength of PBAT/pWWS being improved by ≈20%. Due to talc's lamellar platelet structure and better dispersion, the inclusion of talc into the PBAT/PS blends shows improved rheological properties compared to that of CaCO3.

Properties of thermoplastic maize starch-zein composite films prepared by extrusion process under alkaline conditions

This work investigates the effect of the addition of NaOH on the compatibility and material properties of thermoplastic starch-zein composite films produced by a twin-screw extruder. Thermoplastic starch-zein composite films were produced by melt extrusion of glycerol-plasticized starch and zein (3:1 ratio) treated with different concentrations of sodium hydroxide (NaOH) (0 M, 0.05 M, 0.1 M, and 0.2 M NaOH). Scanning Electron Microscope and Confocal laser Scanning Microscope revealed that the composite without NaOH formed a phase-separated morphology with large zein aggregates within the starch matrix. However, the increase in NaOH concentration reduced the size of zein aggregates within the starch-zein composite films, with 0.2 M NaOH having the smallest size of zein aggregates. Dynamic mechanical analysis showed a decrease in glass transition temperature (Tg) and storage modulus (E'), suggesting more molecular chain mobility and efficient plasticization of starch and zein. This efficient plasticization was also confirmed by Fourier-Transform Infrared spectroscopy (FTIR). As a result, there was an optimal increase of 28% in elongation at break in the starch-zein composite film with 0.2 M NaOH. In conclusion, compatible thermoplastic starch-zein composite films with improved elongation at break can be produced with a twin-screw extruder by adding 0.2 M NaOH.