Glycerol Plasticized Corn Starch Research Articles

Simultaneously reinforcing and toughening plasticized starch film via regenerated cellulose as reinforcing phase

Using regenerated cellulose (RC) as reinforcing phase, a series of glycerol plasticized corn starch (PCS) films were developed via a simple casting pathway. Wide angle X-ray diffraction (WAXD) showed that compared to cellulose crystallites (CC), the RC, dissolved in NaOH/urea aqueous solution and then regenerated by water, exhibited a significant decrease in intermolecular hydrogen bonding. Scanning electron microscopy (SEM) confirmed that compared to CC, a better dispersion of RC in PCS matrix was achieved, and higher tensile strength and elongation at break was obtained. More important, an unusual simultaneous film reinforcing and toughening phenomenon occurred after the addition of RC. Even the weight ratio of RC was up to 20 %, the elongation at break was still higher than that of pure PCS film. A schematic was presented to demonstrate the dispersion features of RC in glycerol plasticized starch film and illustrate this unique mechanical behavior.

Characterization of glycerol-plasticized starch and graphene oxide extruded hybrids

Melt extrusion was chosen to exfoliate graphite oxide (GO) incorporated to glycerol-plasticized cornstarch, aiming to produce hybrids with improved mechanical and barrier properties. The effect of increasing GO content, from 0.5 to 2.0 mass%, on the extruded and compression-molded samples was evaluated by X-ray diffraction (XRD), capillary rheometry, and dynamic mechanical analysis (DMA). The results suggested that the polymer-intercalated filler was well-dispersed within the thermoplastic starch (TPS) matrix, and corroborated the expected interaction between the functional groups of both components. Submitted to aging tests at 80% relative humidity conditions for ninety days, XRD data revealed that GO, independently of its content, could not prevent retrogradation of the starch matrix. Tensile tests, carried out for the hybrid samples before and after the aging tests, indicated improved stiffness as the GO content was increased. Before aging, the E values increased continuously, from 16.3±2.9MPa to 60.0±3.9MPa, with the increase of GO content from 0 to 2.0 mass%. Conversely, the variation of GO content led to a complex behavior in the E values for the aged TPS/GO hybrids. Images obtained by transmission electron microscopy revealed the presence of exfoliated and aggregated GO sheets.

Effect of structure and viscosity of the components on some properties of starch-rich hybrid blends.

Glycerol-plasticized cornstarch and poly(lactic acid) (PLA) were melt-blended alone and at a constant 70:30 (m/m) composition, in the present of an organoclay. The effect of increasing contents of the organoclay on extruded and compression-molded samples was evaluated by X-ray diffraction (XRD), capillary rheometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests. XRD and shear viscosity results obtained for the hybrid components (TPS/organoclay and PLA/organoclay) were correlated with the hybrid blends properties. XRD and TGA results suggested that the organoclay was similarly dispersed within both phases. SEM images revealed improved adhesion between the phases. Shear viscosities results indicated improved compatibilization as the organoclay content was increased. Some of the extruded materials were also submitted to injection molding, and characterized by SEM and by tensile tests. For the extruded and compression-molded samples, improved mechanical properties were obtained for the samples with higher contents of the organoclay. For the injection-molded samples, the mechanical properties seemed to be dependent on the organoclay dispersion.

Food Grade Bioplastic Based on Corn Starch with Banana Pseudostem Fibre/Bacterial Cellulose Hybrid Filler

Food grade bioplastic has become a popular research topic these days. However, further studies are still required in order to develop bioplastic that has comparable mechanical and water barrier properties with synthetic plastic. In this research, to improve mechanical and water barrier properties of plant cellulose filled bioplastic, bacterial cellulose is added to create hybrid filler with banana pseudostem fibre in glycerol plasticized corn starch matrix. The filler banana pseudostem fibre and bacterial cellulose were first dispersed in mixture of glycerol and distilled water, starch was added and mixture was heated until gelatinization occured. The mixture was then casted and dried in oven. Research proved that 10wt% against starch mass was an optimum filler composition, which resulted in the highest mechanical strength of bioplastic. The utilization of hybrid filler showed a decrease in mechanical strength compared with bioplastic with single filler. The ratio of banana pseudostem:bacterial cellulose compotition in hybrid filler that gave the best mechanical properties was 25:75 which resulted in tensile strength 4.599 MPa and modulus 174.1 MPa. Although the utilization of hybrid filler did not improve the mechanical properties of bioplastic, the addition of bacterial cellulose was proven to give positive effect to water barrier properties. Bioplastic filled with hybrid 10wt% banana pseudostem fibre and 35wt% bacterial cellulose had water vapour transmission rate 3.8958 g/m2/hour. The mechanical and water barrier properties of bioplastic was confirmed with SEM, FTIR, and XRD analysis. Soil burial test for 9 days proved that banana pseudostem filler decreased 6.9% of corn starch bioplastic biodegradation rate.

Green Composites Comprising Thermoplastic Corn Starch and Various Cellulose-Based Fillers

Starch microparticles (SM) were prepared by delivering ethanol as the precipitant into a starch paste solution dropwise. Chemically modified starch microparticles (CSM) were fabricated by a reaction with malic acid using the dry-preparation technique. Composites were prepared using CSM and various cellulose materials as fillers within glycerol plasticized–corn starch matrix through the casting process. Microcrystalline cellulose (MC, as reference filler) and two cellulose-enriched materials, namely Asclepias syriaca L. seed hairs (ASSH) and Populus alba L. seed hairs (PSH), were compared in terms of morphology and performance when incorporated within the CSM/S thermoplastic matrix. The effects of cellulose fillers on the morphology, surface, water sorption, and mechanical properties were investigated. The surface water resistance of composite materials was slightly improved through addition of cellulose fillers. Samples containing cellulose fillers presented higher tensile strength but lower elongation values compared with those without fillers.

Using an organically-modified montmorillonite to compatibilize a biodegradable blend

Glycerol-plasticized cornstarch and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) blends were prepared by melt-extrusion at a constant 70:30 (mass/mass) ratio in the presence of a commercial organoclay. The effect of increasing the organoclay content on the morphology and physical properties of the blends was investigated soon after processing and after aging for 12months. After processing, the materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and dynamic mechanical analysis (DMA). The results indicated that increasing clay mineral contents promoted significant improvements in the compatibility between the components. After aging, the samples were characterized by SEM, XRD and small-angle X-ray scattering (SAXS). Unexpectedly, the reduced size of the PHBV dispersed phase and the decreased crystallinity of both phases in the hybrids were maintained. XRD and SAXS results unambiguously proved the presence of both exfoliated layers and a small volume fraction of organoclay aggregates in the aged clay polymer nanocomposites.

Behavior of Cellulose Reinforced Cross-Linked Starch Composite Films Made with Tartaric Acid Modified Starch Microparticles

Tartaric acid modified starch microparticles (TA-SM) previously obtained using the dry preparation technique were introduced as filler within glycerol plasticized-corn starch (GCS), the composites being prepared by casting process. The effects of cellulose addition within the TA-SM-GCS matrix on the structure, surface properties and water sorption, as well as mechanical and thermal properties of starch-based composite films were investigated. The water resistance and thermal stability were slightly improved through addition of high content of cellulose due to the inter-component H-bonding between components. The evaluation of mechanical properties evidenced a significant increase of the tensile strength of the composites with increasing the content level of cellulose.

Influence of natural fillers on the properties of starch-based biocomposite films

Starch microparticles (SMs) were prepared by delivering ethanol into starch solution. Chemically modified starch microparticles (CMSs) by reaction with malic acid were obtained and incorporated within glycerol plasticized-corn starch (GCS) matrix, composites being further prepared by the casting process. Three natural fillers (NFs) – keratin, lignin, and spruce cellulose – were incorporated within the CMS–GCS matrix. The surface properties and water sorption, as well as mechanical and thermal properties of chemically modified starch/plasticized starch/natural filler (CMS/S/NF) films were investigated. The water resistance and thermal stability were improved through addition of NF. Higher tensile strength and lower elongation capacity were also observed.

Preparation and characterization of adipic acid-modified starch microparticles/plasticized starch composite films reinforced by lignin

In this article, starch microparticles (SM) were prepared by delivering ethanol as the precipitant into starch paste solution dropwise. Adipic acid (AA)-modified starch microparticles (AASM) were fabricated using the dry preparation technique. The composites were prepared using AASM as the filler in glycerol plasticized-corn starch (GCS) matrix by the casting process. Two lignins were also compared in terms of structure and reactivity when incorporated within the AASM–GCS matrix. The effects of lignin on the morphology, surface properties, and water sorption, as well as mechanical and thermal properties of starch–lignin composite films were investigated. The surface water resistance and the thermal stability of materials were improved through addition of lignin. Starch–lignin composite materials presented higher tensile strength, but a lower elongation capacity comparatively with those without lignin.

Calcium bentonite as reinforcing nanofiller for thermoplastic starch

Glycerol-plasticized corn starch materials (TPS), reinforced with calcium bentonite, were prepared by melt extrusion. Scanning electron microscopy was used to visualize extrudates morphology. The effects of clay content and of glycerol content on physical properties of extrudates were evaluated. As determined by X-ray diffraction, the increase in glycerol content led to materials with higher B-type crystallinity. Addition of clay resulted in hybrid materials with improved properties in relation to TPS alone, even after conditioning at a high relative humidity for 90 days. X-Ray diffraction was also used to evaluate clay intercalation within the polymeric matrix, before and after conditioning. Results from tensile tests suggested a high degree of exfoliation.

Preparation of a Novel Thermoplastic Starch (TPS) Material using Ethylenebisformamide as the Plasticizer

AbstractIn this paper, ethylenebisformamide was synthesized and used as a novel plasticizer for corn starch to prepare thermoplastic starch (EPTPS). FT‐IR spectra showed that the absorption bands of the C‐O groups of the starch molecules were shifted to lower wavenumbers, which indicated that a strong and stable hydrogen bond had been formed between ethylenebisformamide and starch. By scanning electron microscope (SEM) native individual corn starch granules were proved to transfer to a continuous phase. The crystallinity of native corn starch, GPTPS (glycerol plasticized corn starch) and EPTPS was characterized by X‐ray diffraction (XRD). Water resistance of EPTPS was better than that of GPTPS. It decreased from 50.2% for GPTPS to 37.8% for EPTPS. The mechanical analysis showed that elongation at break increased markedly, being 260% for the EPTPS containing 35% (w/w) ethylenebisformamide. Thermal stability of GPTPSs and EPTPSs was also determined by thermogravimetric analysis (TGA). The glass transition temperature Tg, as measured by dynamic mechanical thermal analysis (DMTA), of EPTPS was higher than that of GPTPS.

Effect of aging on the microstructure of plasticized cornstarch films

Aging of cornstarch films prepared by casting was investigated. Water and glycerol-plasticized cornstarch films were stored at 50% relative humidity over a period of 330 days. Aging was followed by X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD spectra indicated development of B-type crystallinity even for fresh films and that the crystallinity index increased from 0.06 to 0.28 as a function of storage time. AFM images of 270-day-old films revealed that the general morphology and the overall roughness have not changed due to aging. AFM phase contrast images at higher magnification showed an increasing number of ordered domains at the surface of these films, which may be attributed to recrystallization of amylose. No morphological change was observed at least at the surface of the granular region, which is enriched in amylopectin.