Thermal and mechanical properties of fatty acid starch esters

Synthesis, characterization, and antimicrobial activities of a starch-based polymer

Due to the rise of nosocomial infections and the increasing threat of antibiotic resistance, new techniques are required to combat bacteria and fungi. Functional antimicrobial biodegradable materials developed from low-cost renewable resources like polysaccharides would enable greater applications in this regard. Our group has developed and characterized a new antimicrobial polymer using commercially available N-ethyl piperazine and starch via simple one-pot method. The prepared antimicrobial polymer was characterized by FTIR and NMR. In addition, the thermal properties of the synthesized antimicrobial polymer were examined through TGA and DSC. The antimicrobial potential of the prepared material was investigated using the bacteria, Staphylococcus aureus, Escherichia coli, and Mycobacterium smegmatis and a fungi Candida albicans. The result indicates that, as the amount of polymer increases, the antimicrobial activity also increases. SA-E-NPz exhibited a zone of inhibition in the range of 8-13 mm, and the MIC was found to be < 0.625 mg against all four microbes. The antimicrobial activity of polymer coated on fabric was also studied. Furthermore, the cytotoxicity studied against human fibroblast cell lines showed that the prepared polymer is non-toxic to the cells. The study concluded that the synthesized polymer shows good antimicrobial activity, is non-toxic to human fibroblast cells, and thus can be used for wound dressing or textile applications.

Starch ester film properties: The role of the casting temperature and starch its molecular weight and amylose content

Oleic acid and 10-undecenoic acid were used to esterify corn, tapioca, potato and a waxy potato starch, with a maximum degree of substitution of 2.4 and 1.9 respectively. The thermal and mechanical properties were investigated as a function of the amylopectin content and M_w of starch, and by the fatty acid type. All starch esters had an improved degradation temperature regardless of their botanical origin. While the T_g did increase with increasing amylopectin content and M_w, it decreased with increasing fatty acid chain length. Moreover, films with different optical appearances were obtained by varying the casting temperature. SEM and polarized light microscopy showed that films cast at 20 °C had porous open structures with internal stress, which was absent when cast at higher temperatures. Tensile test measurements revealed that films had a higher Young's modulus when containing starch with a higher M_w and amylopectin content. Besides that, starch oleate films were more ductile than starch 10-undecenoate films. In addition, all films were resistant to water at least up to one month, while some light-induced crosslinking took place. Finally, starch oleate films showed antibacterial properties against Escherichia coli, whereas native starch and starch 10-undecenoate did not.

Synthesis and Properties of Fully Biobased Crosslinked Starch Oleate Films

Starch oleate (degree of substitution = 2.2) films were cast and crosslinked in the presence of air using UV curing (UVC) or heat curing (HC). A commercial photoinitiator (CPI, Irgacure 184) and a natural photoinitiator (NPI, a mixture of biobased 3-hydroxyflavone and n-phenylglycine) were used for UVC. No initiator was used during HC. Isothermal gravimetric analyses, Fourier Transform Infrared (FTIR) measurements, and gel content measurements revealed that all three methods were effective in crosslinking, with HC being the most efficient. All methods increased the maximum strengths of film, with HC causing the largest increase (from 4.14 to 7.37 MPa). This is consistent with a higher degree of crosslinking occurring with HC. DSC analyses showed that the T_g signal flattened as film crosslink densities increased, even disappearing in the case of HC and UVC with CPI. Thermal gravimetric analyses (TGA) indicated that films cured with NPI were least affected by degradation during curing. These results suggest that cured starch oleate films could be suitable for replacing the fossil-fuel-derived plastics currently used in mulch films or packaging applications.

Polysaccharides and lipoproteins as reactants for the synthesis of pharmaceutically important scaffolds: A review

The growing number of diseases in the past decade has once again highlighted the need for extensive research on the development of novel drugs. There has been a major expansion in the number of people suffering from malignant diseases and types of life-threatening microbial infections. The high mortality rates caused by such infections, their associated toxicity, and a growing number of microbes with acquired resistance necessitate the need to further explore and develop the synthesis of pharmaceutically important scaffolds. Chemical entities derived from biological macromolecules like carbohydrates and lipids have been explored and observed to be effective agents in the treatment of microbial infections and diseases. These biological macromolecules offer a variety of chemical properties that have been exploited for the synthesis of pharmaceutically relevant scaffolds. All biological macromolecules are long chains of similar atomic groups which are connected by covalent bonds. By altering the attached groups, the physical and chemical properties can be altered and molded as per the clinical applications and needs, this ring them potential candidates for drug synthesis. The present review establishes the role and significance of biological macromolecules by articulating various reactions and pathways reported in the literature.

A more efficient synthesis and properties of saturated and unsaturated starch esters

This work presents a series of starch esters synthesized via 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD) catalyzed transesterifications in dimethyl sulfoxide (DMSO). The reaction was performed with saturated and unsaturated fatty acids (8, 11, and 18 carbon atoms). The degree of substitution (DS) was raised by purging the reaction flask with nitrogen instead of simply performing the reaction under a nitrogen atmosphere. The increase of DS was most obvious for long-chain fatty acids, as an almost complete DS was observed for starch stearate (2.8) and starch oleate (2.7). The products were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Starch esters from unsaturated fatty acids have a lower T_g than their saturated analogues. Moreover, contact angle and moisture uptake measurements showed increased hydrophobicity for all starch esters in comparison to pristine starch. Our results show a more efficient method for synthesizing a biobased material that steers into the direction of a material that could replace conventional plastics.

Polyester-Based Coatings for Corrosion Protection

The article is the first review encompassing the study and the applications of polyester-based coatings for the corrosion protection of steel. The impact of corrosion and the challenges encountered thus far and the solutions encountered in industry are addressed. Then, the use of polyesters as a promising alternative to current methods, such as phosphating, chromating, galvanization, and inhibitors, are highlighted. The classifications of polyesters and the network structure determine the overall applications and performance of the polymer. The review provides new trends in green chemistry and smart and bio-based polyester-based coatings. Finally, the different applications of polyesters are covered; specifically, the use of polyesters in surface coatings and for other industrial uses is discussed.

Onion and garlic polysaccharides: A review on extraction, characterization, bioactivity, and modifications

Allium cepa (onion) and Allium sativum (garlic) are important members of the Amaryllidaceae (Alliaceae) family and are being used both as food and medicine for centuries in different parts of the world. Polysaccharides have been extracted from different parts of onion and garlic such as bulb, straw and cell wall. The current literature portrays several studies on the extraction of polysaccharides from onion and garlic, their modification and determination of their structural (molecular weight, monosaccharide unit and their arrangement, type and position of glycosidic bond or linkage, degree of polymerization, chain conformation) and functional properties (emulsifying property, moisture retention, hygroscopicity, thermal stability, foaming ability, fat-binding capacity). In this line, this review, summarizes the various extraction techniques used for polysaccharides from onion and garlic, involving methods like solvent extraction method. Furthermore, the antioxidant, antitumor, anticancer, immunomodulatory, antimicrobial, anti-inflammatory, and antidiabetic properties of onion and garlic polysaccharides as reported in in vivo and in vitro studies is also critically assessed in this review. Different studies have proved onion and garlic polysaccharides as potential antioxidant and immunomodulatory agent. Studies have implemented to improve the functionality of onion and garlic polysaccharides through various modification approaches. Further studies are warranted for utilizing onion and garlic polysaccharides in the food, nutraceutical, pharmaceutical and cosmetic industries.

Modified Starch-Based Adhesives: A Review

Consumer trends towards environmentally friendly products are driving plastics industries to investigate more benign alternatives to petroleum-based polymers. In the case of adhesives, one possibility to achieve sustainable production is to use non-toxic, low-cost starches as biodegradable raw materials for adhesive production. While native starch contains only hydroxyl groups and has limited scope, chemically modified starch shows superior water resistance properties for adhesive applications. Esterified starches, starches with ester substituents, can be feasibly produced and utilized to prepare bio-based adhesives with improved water resistance. Syntheses of esterified starch materials can involve esterification, transesterification, alkylation, acetylation, succinylation, or enzymatic reactions. The main focus of this review is on the production of esterified starches and their utilization in adhesive applications (for paper, plywood, wood composites, fiberboard, and particleboard). The latter part of this review discusses other processes (etherification, crosslinking, grafting, oxidation, or utilizing biobased coupling agents) to prepare modified starches that can be further applied in adhesive production. Further discussion on the characteristics of modified starch materials and required processing methods for adhesive production is also included.

Cassava and banana starch modified with maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG): A comparative study of their physicochemical properties as coatings

This study proposes a simple route to obtain starch grafted copolymers from cassava and banana starches chemically modified with amphiphilic maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG). The starches were extracted from cassava (StC) and banana (StB) pulp and characterized by FTIR spectroscopy, amylose content, scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and average molecular weight. Starches were chemically modified with amphiphilic Ma-mPEG in three mass ratios 1:1, 1:2 and 1:3. Thermal behavior and interactions of Ma-mPEG/starch in the St-g-(Ma-mPEG) copolymers were studied by DSC and TGA. The T_g values showed a higher plasticizer effect in the copolymers obtained from StC. Films were formed from StC-g-(Ma-mPEG) and StB-g-(Ma-mPEG) copolymers, thermal and morphological properties were studied. An increase in the mass ratios of Ma-mPEG and the absence of the glycerol in the formulations formed homogeneous films. StC-g-(Ma-mPEG) 1:3 with 2% concentration showed a potential use as coating in strawberries, presenting a lower weight loss (15.5 ± 5.7%) than the control sample (18.6 ± 3.3%).

Reaction Mechanisms Applied to Starch Modification for Biodegradable Plastics: Etherification and Esterification

Although many studies are being actively conducted to develop biodegradable plastic materials, most of these reports focused more on efficiency or performance improvement than on the reaction mechanism. This paper discussed the reaction mechanism applied to starch modification by etherification and esterification, which are the most studied in the field of biodegradable plastics. In the starch-reforming reaction by etherification, the effects of the reaction temperature, pH, solvent, and by-products on the chemical structure and physical properties of biodegradable plastics were discussed. In esterification, the structure of the substituents and the reaction solvents were examined. As a material that can replace plastics, the aim is to help derive new ideas on the design of reaction condition that can expand the use of starch.

A Novel Approach of Bioesters Synthesis through Different Technologies by Highlighting the Lowest Energetic Consumption One

Fatty acids esters have a wide application as bioplasticizers and biolubricants in different industries, obtained mainly in classic batch reactors, through an equilibrium complex reaction, that involves high temperatures, long reaction times, vigorously stirring, and much energy consumption. To overcome these shortcomings, we synthesized a series of fatty acid esters (soybean oil fatty acids being the acid components with various hydroxyl compounds) through novel low energy consumption technologies using a bubble column reactor, a microwave field reactor and for comparison meaning, a classic batch reactor. The obtained bioesters physicochemical properties were similar to one another, a good concordance among their rheological properties was obtained, but the energetic consumption is lower when using the bubble column or the microwave reactors instead of the classical batch reactor.

Mechanical Behavior Modelling and Filler Geometry Effect of Glass Filler Reinforced Starch-Epoxy Hybrid Matrix Composites

The aim of the present study is to investigate the inclusion geometry and concentration effect on the quasi-static properties of a starch-epoxy hybrid matrix composite. The composites investigated consisted of a starch-epoxy hybrid matrix reinforced with four different glass inclusions such as 3 mm long chopped strands, 0.2 mm long short glass fibers, glass beads (120 μm in diameter) and glass bubbles (65 μm in diameter) at different concentrations. The flexural modulus and the strength of all materials tested were determined using three-point bending tests. The Property Prediction Model (PPM) was applied to predict the experimental findings. The model predicted remarkably well the mechanical behavior of all the materials manufactured and tested. The maximum value of the flexural modulus in the case of the 3 mm long chopped strands was found to be 75% greater than the modulus of the hybrid matrix. Furthermore, adding glass beads in the hybrid matrix led to a simultaneous increase in both the flexural modulus and the strength.

Agarose Stearate-Carbomer940 as Stabilizer and Rheology Modifier for Surfactant-Free Cosmetic Formulations

Some commonly used surfactants in cosmetic products raise concerns due to their skin-irritating effects and environmental contamination. Multifunctional, high-performance polymers are good alternatives to overcome these problems. In this study, agarose stearate (AS) with emulsifying, thickening, and gel properties was synthesized. Surfactant-free cosmetic formulations were successfully prepared from AS and carbomer₉₄₀ (CBM₉₄₀) mixed systems. The correlation of rheological parameter with skin feeling was determined to study the usability of the mixed systems in cosmetics. Based on rheological analysis, the surfactant-free cosmetic cream (SFC) stabilized by AS-carbomer₉₄₀ showed shear-thinning behavior and strongly synergistic action. The SFC exhibited a gel-like behavior and had rheological properties similar to commercial cosmetic creams. Scanning electron microscope images proved that the AS-CBM₉₄₀ network played an important role in SFC’s stability. Oil content could reinforce the elastic characteristics of the AS-CBM₉₄₀ matrix. The SFCs showed a good appearance and sensation during and after rubbing into skin. The knowledge gained from this study may be useful for designing surfactant-free cosmetic cream with rheological properties that can be tailored for particular commercial cosmetic applications. They may also be useful for producing medicine products with highly viscous or gel-like textures, such as some ointments and wound dressings.

Effect of cellulose and starch fatty acid esters addition on microstructure and physical properties of arabinoxylan films

Arabinoxylan (AX) and cellulose were extracted from wheat straw, whereas starch was extracted from potato peel. Thereafter, cellulose and starch were esterified with lauric, myristic, palmitic and stearic acids to prepare corresponding cellulose (CFAs) and starch fatty acid esters (SFAs) with DS 2.1-2.8. XRD study revealed remarkable loss of crystallinity in cellulose and starch due to fatty acid esterification. The addition of palmitate and stearate esters of cellulose and starch to AX formed laminar film microstructures which limited water vapor permeability whereas films prepared by blending AX with laurate and myristate esters of starch and cellulose were less effective as water vapor barrier due to their non-layer microstructures. The laminar structures also resulted significant reduction in mechanical strength of the composite films. Furthermore, all AX-CFAs and AX-SFAs films were thermally more stable than native composite films. These films might be used to produce industrially useful coating material for food products.

Chemical and thermal characteristics of soluble polysaccharides from fruit pericarps of the Algerian Argania spinosa

Soluble polysaccharides were isolated from fruit pericarps of the Algerian Argania spinosa. The cell wall fraction was subjected to sequential extractions with H2O (2 × 2 h at 100°C), EDTA (1%, 6 h at 80°C) and KOH (1 and 4 M, 14 h at 25°C). The structures of the obtained polysaccharide fractions were characterized using gas chromatography (GC), infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The presence of arabinose, galactose and rhamnose in the pectin fractions suggests the presence of rhamnogalacturonan, while the abundance of xylose in the hemicellulosic fractions indicates the presence of xylan. The DSC data revealed the endothermal behavior of all the soluble polysaccharides and only two thermal transitions, the glass transition (Tg) and the fusion transition (Tf) have been recorded.

A Review of Wood Biomass-Based Fatty Acids and Rosin Acids Use in Polymeric Materials

In recent decades, vegetable oils as a potential replacement for petrochemical materials have been extensively studied. Tall oil (crude tall oil, distilled tall oil, tall oil fatty acids, and rosin acids) is a good source to be turned into polymeric materials. Unlike vegetable oils, tall oil is considered as lignocellulosic plant biomass waste and is considered to be the second-generation raw material, thus it is not competing with the food and feed chain. The main purpose of this review article is to identify in what kind of polymeric materials wood biomass-based fatty acids and rosin acids have been applied and their impact on the properties.

Hydrophobizing cellulose surfaces via catalyzed transesterification reaction using soybean oil and starch

Biodegradable modified natural polymers have great potential in curbing the threat of plastic pollution, but are still uncompetitive to petrochemical-based plastic. In this study, starch was hydrophobized by treating starch-dimethyl sulfoxide solutions with soybean oil at high temperature in the presence of sodium carbonate, then spray-coated on paper. The modified starch was evaluated by Fourier-transform infrared spectroscopy analysis and contact angle value measurement of coated paper. FTIR analysis confirmed the substitution of hydroxyl groups with fatty acid ester and provided an estimate of the degree of substitution. The contact angle value of starch-coated paper surfaces was 121°, and was 111° after 10 min, demonstrating the high hydrophobicity and potential of the modified starch coating as a water-resistant treatment. The high hydrophobicity of the coated paper was due to formation of a textured surface with two levels of roughness, caused by the deposition of rough hydrophobic starch particles on paper fibers.

Effect of the Degree of Substitution on the Hydrophobicity, Crystallinity, and Thermal Properties of Lauroylated Amaranth Starch

In this paper, we consider amaranth starch extracted from the seeds of Amaranthus hypochondriacus L. An amphiphilic character is conferred to the starch by a chemical modification, which involves an esterification by lauroyl chloride at three modification levels. The degree of substitution (DS) after the modification ranged from 0.06 to 1.16. X-ray photoelectron spectroscopy analysis confirmed the presence of fatty acyl chains on the surface of the esterified starches. The hydrophobicity of starches was confirmed by their adsorption isotherms, which showed a decrease in the moisture adsorption of lauroylated as DS increased. X-ray diffraction analysis revealed a higher crystallinity, which was observed in the two samples subjected to the highest levels of modification. A higher crystallinity is related to a higher gelatinization enthalpy. These results are in agreement with the thermal characterization obtained by differential scanning calorimetry (DSC). An inhibition of the retrogradation properties of lauroylated amaranth starches was also observed.

Dual modification of various starches: Synthesis, properties and applications

The problems associated with native starches (NSs) and single modified starches were stated in order to justify dual modification of various starches. Broadly, there are two types of dual modification, i.e., homogeneous dual modification and heterogeneous dual modification. The combination of two physical modifications, e.g., (extrusion/annealing); two chemical modifications, e.g., (succinylation/cross-linking) and two enzymes modification (α-amylase/pullulanase) falls under the former classification and the latter classification is the combination of two of each of the differently stated modifications, e.g., acetylation/annealing, extrusion/succinylation, and microwave-assisted phosphorylation, etc. The classification, synthesis, properties and applications of dually modified starches were discussed. There is an attempt to elucidate the problems of each of the single modification in order to justify dual modifications. In dual modifications, the order of reactions, the reaction conditions, the medium of reaction, and the botanical sources of the various starches are very important parameters.

Preparation and Properties of Jute Fiber Long-Chain Fatty Acid Esters in Supercritical Carbon Dioxide

A two-step method involving continuous screw-extrusion steam explosion (CSESE) pretreatment and esterification in supercritical carbon dioxide (scCO₂) is used to prepare long-chain fatty acid-modified jute fiber. The weight gain percentage (WG %) of CSESE-pretreated jute laurate (JL) was 110.7% when esterification was carried out in scCO₂ at 14 MPa and 100 °C for 2 h. The corresponding WG % was 105.5% when esterification was instead carried out in pyridine at 100 °C for 2 h. Scanning electron microscopy and X-ray diffraction indicated that CSESE pretreatment enhanced the reactivity of jute fiber, with esterification in scCO₂ simultaneously occurring on the fibers surface and internal walls. The glass transition temperature of esterified jute was approximately 119 °C, indicating that it could be hot processed over a wide temperature range. The esterified jute had an oil absorption ratio of 17.01 g/g, so it can be used as an oil absorption material.

Hierarchical Structure and Thermal Property of Starch-Based Nanocomposites with Different Amylose/Amylopectin Ratio

Starch-based materials with reinforced properties were considered as one of the most promising materials to replace the petro-based packaging products, and actually, the molecular structures of starch usually determined the structures and properties of end-used starchy products. Here, starch-based nanocomposites were fabricated by starch esters derived from native starches with different amylose contents and organically modified montmorillonite (OMMT). The fractured surface under scanning electron microscopy (SEM) exhibited wrinkles formed by macromolecular aggregation owing to the interaction competition between the plasticizer and nanofiller with the starch ester. The more intense interaction within amylopectin-rich films promoted the formation of much randomly exfoliation of OMMT observed by Transmission electron microscopy (TEM). As the amylose content increased, the interaction between the starch ester and the nanofiller was weakened, leading to the dispersion morphology of an ordered arrangement and partly intercalated structures in the dimension of 12.92 to 19.77 nm. Meanwhile, such interaction also affected both the inner ordered structure integrity of starch ester and the layer structure consistency of nanofiller according to X-ray diffraction results. Further, the stronger interaction between amylopectin and the nanofiller endowed higher thermal stability to the amylopectin-rich starch-based nanocomposites. In short, these results are beneficial for the application of starch-based nanocomposites in the food packaging industry by regulating the interaction between starch and nanofillers.

Evaluation of structural, functional, and anti-oxidant potential of differentially extracted polysaccharides from potatoes peels

Potato peel was used for the extraction of three types of polysaccharides (PW, PAL, and PAC) using water, alkaline, and acid treatments, respectively. The structure of the PP polysaccharides was examined by means of Fourier transform infrared spectroscopy (FT-IR) analysis and Gas chromatography-mass spectrometry (GC-MS). The results suggest that the extracted polysaccharides constituted essentially three functional groups: CO, CH, and OH. The polysaccharides were comprised of low proportions of proteins, 17-23% uronic acids, and approximately 70% carbohydrates. PAL, PW, and PAC with molecular weights of 2.25 × 10³, 2.18 × 10³, and 1.92 × 10³ kDa, respectively, were composed of rhamnose, xylose, mannose, arabinose, glucose, and galactose. Functional properties (solubility, oil holding capacity, foaming, and emulsion properties) of these polysaccharides were evaluated. Among three, PAL showed the highest fat-binding capacity which was 7.50 g/g with the solubility of 95.06%. The three polysaccharides possessed appreciable in vitro anti-oxidant (scavenging DPPH and ABTS⁺ radicals, chelating ferrous ions, and reducing power) potential. PAL exhibited the strongest reducing power, scavenging activity on DPPH radicals and chelating capability on ferrous ions. PP polysaccharides can be used as promising natural antioxidants in food, pharmaceutical, and cosmetic preparations.

Thermal and Antioxidant Properties of Polysaccharides Sequentially Extracted from Mulberry Leaves (Morus alba L.)

Polysaccharides from natural plant products are gaining considerable attention due to their multi-faceted health effects, as well their functional applications in food production. We reported the sequential extraction of mulberry leaf polysaccharides (MLPs) with hot buffer (HBSS), chelating agent (CHSS), dilute alkali (DASS) and concentrated alkali (CASS), in order to obtain polysaccharide fractions. Monosaccharide analysis proved that galactose (27.07%) and arabinose (25.99%) were the major sugars in HBSS, whereas arabinose (30.55%) was the major sugar in CHSS, and glucose was the major sugar in DASS (24.96%) and CASS (27.51%). The molecular weights of the polysaccharide fractions were 7.812 × 10³ (HBSS), 3.279 × 10³ (CHSS), 6.912 × 10³ (DASS), and 1.408 × 10³ kDa (CASS). HBSS and CASS showed the largest peak temperature and the highest endothermic enthalpy, respectively. Different antioxidant assays showed that the MLPs possessed appreciable antioxidant activities in a dose-dependent manner. At 5 mg/mL, HBSS and DASS possessed the largest 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity (96.82%). HBSS exhibited the highest reducing power, and DASS rendered the strongest ABTS radical scavenging activity (99.69%). CHSS performed the best hydroxyl radical scavenging activity (64.22%) and Fe²⁺-chelating ability (96.36%). Our results suggested that MLPs could be a promising source of natural antioxidants for use in the food, pharmaceutical, and cosmetic industries.

Thermal and mechanical properties of tailor-made unbranched α-1,3-glucan esters with various carboxylic acid chain length

The convenient and environmentally friendly method for in vitro polymerization catalyzed by glucosyltransferase, designated as GtfJ, extracted from recombinant E. Coli was used to synthesize tailor-made α-1,3-glucan (α-1,3-d-glucan) having moderate molecular weight (M_w=2.0×10⁵) and no branches. With the aim to improve thermoplasticity of this polysaccharide, after in vitro synthesis, chemical modification by acylation was selected and then fully substituted α-1,3-glucan esters were successfully obtained via both homogeneous and heterogeneous methods. Thermal degradation temperature of α-1,3-glucan esters was improved after esterification and dependent on neither side chain length nor synthesis methods. DSC curves suggested a presence of crystal structure in α-1,3-glucan acetate, propionate, butyrate, valerate and hexanoate due to detectable melting endotherm, whereas octanoate exhibited amorphous behavior. T_m's of α-1,3-glucan esters were relatively high, more than 200°C, in comparison with commercial plastics. The shorter chain length of acid component, the higher T_m and T_g ester products exhibited. In addition, tensile strength of α-1,3-glucan esters decreased in contrast with elongation at break with an increase in alkyl chain length of an acid component. Thus, crystalline and amorphous α-1,3-glucan esters with adjustable thermal and mechanical properties obtained from this research are promising materials for continuing applied researches and contemplating the future application in bio-based thermoplastic materials.

Influence of fatty chain length and starch composition on structure and properties of fully substituted fatty acid starch esters

A series of almost fully substituted Fatty Acid Starch Esters (FASEs) has been obtained in a homogeneous LiCl/DMAc medium by grafting octanoyl (C8), lauroyl (C12) and palmitoyl (C16) chlorides onto 3 starch species: Amylo-Maize, Potato and Waxy Maize. Structure-property relationships of FASEs are investigated as a function of both fatty acid chain length and amylose/amylopectin ratio of the starch. The structural study has revealed a layered type organization in which starch chain planes are separated by fatty chains. The latter are interpenetrated and/or tilted for FASE-C16 whatever the origin of the starch is, and fatty chains partially crystallizes into a structure with hexagonal symmetry. FASEs with C8 and C12 side chains are totally amorphous. The mechanical behavior of FASEs is shown to depend on both side chain length and amylose/amylopectin ratio, and an increase in material ductility is observed at increasing amylose content for C8 and C12 side chains.

Catalytic Transesterification of Starch with Plant Oils: A Sustainable and Efficient Route to Fatty Acid Starch Esters

The transesterification of maize starch with olive oil or high oleic sunflower oil was studied under homogeneous conditions in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. Most importantly, this method used two renewable resources directly, without any pretreatment or derivatization, for the synthesis of polymeric materials with desirable properties. Moreover, the solvent, oils, and catalyst could be recovered through facile work-up and reused for further modifications. The obtained fatty acid starch esters (FASEs) were highly soluble in common organic solvents and were thoroughly characterized. Degrees of substitution (DS) were calculated using ³¹ P NMR spectroscopy, and DS values of approximately 1.3 were obtained. Differential scanning calorimetry analysis revealed thermal transitions of the modified starches at approximately 80-90 °C. Films were produced from these FASEs, and their hydrophobic surfaces were characterized using contact-angle measurements. Furthermore, mechanical properties were examined using tensile strength measurements and showed approximately 40 and 80 % elongation at break for modified maize starch and modified amylose from maize, respectively.

Lipid functionalized biopolymers: A review

Lipids are the main source of energy and widely used for various applications. In this review, the modification of lipids by using them in combination with other biomaterials like natural and synthetic polymers is elaborated. These new blends have characteristic features of both polymers and are characterized by different techniques (NMR, DSC, TGA, IR and Raman spectroscopy etc.) to understand their structure, properties and functional behavior. Lipids are hydrophobic, have anti-oxidant and anti-bacterial properties and thus impart hydrophobicity and flexibility to the polymers. While the polymers, on the other hand, make the lipids tougher. Properties of few polymers such as starch, polyethylene protein and chitosan that have brittleness, low combustion rate and hydrophobicity, are improved by incorporation of lipids ultimately increased their flexibility, combustion rate and hydrophobicity respectively. This review article is also focused on emerging fields for the applications of these composite materials. The most notable application of composite materials are in the field of paint industry.

In vitro synthesis of linear α-1,3-glucan and chemical modification to ester derivatives exhibiting outstanding thermal properties

Bio-based polymer is considered as one of potentially renewable materials to reduce the consumption of petroleum resources. We report herein on the one-pot synthesis and development of unnatural-type bio-based polysaccharide, α-1,3-glucan. The synthesis can be achieved by in vitro enzymatic polymerization with GtfJ enzyme, one type of glucosyltransferase, cloned from Streptococcus salivarius ATCC 25975 utilizing sucrose, a renewable feedstock, as a glucose monomer source, via environmentally friendly one-pot water-based reaction. The structure of α-1,3-glucan is completely linear without branches with weight-average molecular weight (Mw) of 700 kDa. Furthermore, acetate and propionate esters of α-1,3-glucan were synthesized and characterized. Interestingly, α-1,3-glucan acetate showed a comparatively high melting temperature at 339 °C, higher than that of commercially available thermoplastics such as PET (265 °C) and Nylon 6 (220 °C). Thus, the discovery of crystalline α-1,3-glucan esters without branches with high thermal stability and melting temperature opens the gate for further researches in the application of thermoplastic materials.