Starch-based Binder Research Articles

Optimal composition of a starch-hemp agro-composite materials

The use of Hemp/Lime concrete has gained popularity due to its lightweight, low thermal conductivity, and good sound absorption properties. However, the emission of CO2 from lime and the non-durability and non-recyclability of lime-hemp concrete make it less sustainable. In this paper, we studied new Starch/Hemp agro-composite materials as an alternative building material. The physical and mechanical properties of these materials strongly depend on the mixture of hemp shive and binder, making it challenging to determine the optimal composition for specific applications. This paper presents the experimental results obtained from one hundred and eighty specimens for the optimal composition. We used thirty different mixtures, including three Hemp/Starch (H/S) ratios of 6, 8, and 10, and five mixtures with hemp shive sizes of 5 mm (Hk), 15 mm (Hi), and 20 mm (Hj). We studied and analyzed the influence of the H/S ratio and hemp shive size (Hk, Hi, Hj) on mechanical properties, including density, flexural tensile strength, compressive strength, Young's modulus, and Poisson's ratio. The experimental results demonstrate that the starch-based binder allows for the transfer of mechanical strength to the hemp shive and gives the desired shape to the agro-composite material. The equations describing the evolution of the physical and mechanical characteristics (ρ, σc, σt, E, ν) should help researchers and building professionals manufacture this agro-resource and determine the optimal composition for building based on intended applications.

Potential of Using Natural and Synthetic Binder in Wood Composites

The physical and mechanical properties of particleboard bonded with different cooking percentages of seaweed (Kappaphycus alvarezii), with different percentages of starch and different percentages of adhesives, and wood plastic composite (WPC) from High-Density Polyethlene (HDPE) with Acacia mangium wood powder were determined in this study. Seaweed mixed with different percentages of sulfuric acid (30%, 50%, 70%) and Sodium Hydroxide (70%, 50%, 30%) were prepared as a binder for particleboard. For a starch-based binder, different percentages of starch (10%, 15%, 20%) were prepared, before producing particleboard with different amounts of binder (20%, 25%, 30%). As for WPC, wood powders were bonded with different percentages of HDPE content (70%, 80%, 90%). Results indicated that WPC at 90% HDPE shows the best performance in the water absorption (0.07%) and thickness swelling test (2.54%). Starch-based particleboard recorded the highest Modulus of Elasticity (MOE) value (1115.07 N/mm2 at 15% starch with 30% amount of binder), while WPC (90% HDPE) and starch-based particleboard (10% starch with 20% amount of binder) both recorded the highest Modulus of Rupture (MOR) at the same value, which is 7.84 N/mm2. Starch-based particleboard has a better internal bond, which is 0.05 N/mm2. However, seaweed-based particleboard has a higher density value, which is 0.6 g/cm3.

Innovative Insulating Materials from Coriander (Coriandrum sativum L.) Straw for Building Applications

Straw represents 60-80% of the aerial part of the coriander plant. Because of the increasing demand for vegetable oil from fruits for food, cosmetics or the chemical industry, the availability of straw will grow strongly in the future. Its high lignocellulose content (62%) makes this crop by-product an interesting raw material for producing bio-based building materials. Bulk materials can be obtained by refining the straw through twin-screw extrusion in the presence of water. The fiber aspect ratio of refined straw can be varied (22.9-26.5) by applying different liquid/solid ratios (0.4-1.0), leading to a variation in the tapped density of the resulting bulk material (110-61 kg/m3). For the lowest density, thermal conductivity is 47.3 mW/(m.K). Twin-screw refining can also be conducted from an aqueous borax solution. Refined straw thus becomes fire-proofed, making it usable as loose fill in housing. Insulation blocks of medium density, associating straw and a starch-based binder, can also be produced through compression molding. With a density of 155 kg/m3 and a thermal conductivity of 55.6 mW/(m.K), the optimal cohesive blocks (7.5 mm milled straw and 15% binder), cold-pressed at 87 kPa for 30 s, are promising alternatives for the thermal insulation of buildings (e.g., filling of walls, interior partitions, etc.).

Effect of Biodegradable Binder Properties and Operating Conditions on Growth of Urea Particles in a Fluidized Bed Granulator.

Granulation is an important step during the production of urea granules. Most of the commercial binders used for granulation are toxic and non-biodegradable. In this study, a fully biodegradable and cost-effective starch-based binder is used for urea granulation in a fluidized bed granulator. The effect of binder properties such as viscosity, surface tension, contact angle, penetration time, and liquid bridge bonding force on granulation performance is studied. In addition, the effect of fluidized bed process parameters such as fluidizing air inlet velocity, air temperature, weight of primary urea particles, binder spray rate, and binder concentration is also evaluated using response surface methodology. Based on the results, binder with higher concentration demonstrates higher viscosity and higher penetration time that potentially enhance the granulation performance. The viscous Stokes number for binder with higher concentration is lower than critical Stokes number that increases coalescence rate. Higher viscosity and lower restitution coefficient of urea particles result in elastic losses and subsequent successful coalescence. Statistical analysis indicate that air velocity, air temperature, and weight of primary urea particles have major effects on granulation performance. Higher air velocity increases probability of collision, whereby lower temperature prevents binder to be dried up prior to collision. Findings of this study can be useful for process scale-up and industrial application.

Study of Thermal Degradation of Starch-Based Binder by TG-DTG-DSC, Py-GC/MS and DRIFTS

Study of Thermal Degradation of Starch-Based Binder by TG-DTG-DSC, Py-GC/MS and DRIFTS

The influence of starch-based bio-latex on microstructure and surface properties of paper coating

Abstract The microstructure of coating layers has important effects on final properties of paper. Eco-friendly bio-latex derived from sustainable starch has being increasingly used in paper coatings to substitute part of the petroleum-based synthetic latex as pigment binder. The influence of starch-based bio-latex on microstructure and surface properties of coatings such as surface composition, surface morphology, void fraction and water absorbency was studied in this paper. X-ray photoelectron spectroscopy (XPS) results showed that bio-latex addition led to a nearly linear decrease in surface carbon content for coatings dried at high temperature. Scanning electron microscope (SEM) images demonstrated that bio-latex addition may cause a lack of binder film at the coating surface that binds pigment particles, which was in agreement with the XPS results. The coatings demonstrated a marginal increase in surface roughness and some decrease in gloss with the addition of bio-latex, as was expected when starch-based binder was used. Unexpectedly, the void fraction of coatings increased slightly, which was contrary to the case in conventional cooked starch. The coatings had a significant decline in water contact angle after bio-latex addition, indicating a considerable increase in water absorbency. The changes in coating microstructure may be attributed to the unique core-shell structure and water-swollen nature of starch-based bio-latex particles.

New insulation fiberboards from sunflower cake with improved thermal and mechanical properties

New thermal insulation fiberboards were manufactured by compression molding from a cake generated during the sunflower biorefinery. Fiberboards were cohesive mixtures of a natural binder and lignocellulosic fibers from sunflower cake. The natural binder ensured the board cohesion, and fibers acted as reinforcing fillers. The influence of molding conditions, i.e. binder type and binder content, on board density, mechanical and heat insulation properties was examined. The medium-density board containing 20% starch-based binder was a good compromise between mechanical and heat insulation properties (78 mW/m K thermal conductivity). It could be positioned on walls and ceilings for thermal insulation of buildings.

ANALYSIS OF SELECTED TECHNOLOGICAL PROPERTIES OF GREEN SANDS WITH STARCH-BASED ADDITIVES

The paper presents the results of determination the effect of addition native starch and mineral-starch mixes on selected technological properties of sands. Study was carried out on permeability, compressive strength and wear resistance of molding. Green sand with bentonite and silica sand was compared with green sand with addition Superior Standard native starch or addition of mineral-starch composition in form of binder Albertine F/1. The main difference in applied starch materials is characteristic property of native starch, which is un-soluble in cold water, so in this case it was difficult to bond water added to the moulding sand during mixing of ingredients. However Albertine F/1 starch-based binder is mixture of starch and aluminosilicates, whereby the bonding of water added into moulding sand during ingredients mixing is more efficient.

Fabrication of Short Graphite Fiber Preforms for Liquid Metal Infiltration

Starch-based and paraffin wax (PW)-based binders were used to fabricate short graphite fiber preforms for liquid metal infiltration. The effects of different binder components and debinding process parameters on the properties of short graphite fiber preforms were investigated. The results indicate that the graphite fiber preforms with appropriate porosity of 58-62% and relatively high compressive strength of about 2-3 MPa can be made by starch-based and PW-based binders. The graphite fiber preforms made from the PW-based binder exhibit higher compressive strength than that of the starch-based binder. Graphite fiber reinforced aluminum composites fabricated by utilizing these preforms through vacuum pressure infiltration have relatively high density of 98.5% and thermal conductivity of 186.3 W/m K, proving the applicability of the prepared preforms for liquid metal infiltration.

Debinding Process of a Starch-Based Binder in Metal Injection Moulding

In this study, a combination of starch, glycerol, linear low density polyethylene (LLDPE) and other additives was utilized as the binder composition. The effect of different parameters such as thickness, temperature and time on debinding process of green parts was investigated. Discs of different thicknesses consisting of 2, 2.7 and 3 mm were submitted to the water bath in order to obtain curves of time versus remaining mass of binder. Moreover, the injected tensile bar test specimens was utilized to observe specially the effect of temperature on rate of binder extraction from the green parts. The experiments were conducted at three sets of temperatures including 70, 80 and 90°C. The rate of binder removing considerably increased by decreasing the thickness of the discs. On the other hand, proportion of removed binder in injected tensile bar specimens increased in higher temperatures. The debinding process was successfully performed on injected tensile bars and the components did not suffer from any cracks and swellings. Moreover, the results show that more than 80% of the binder system can be extracted in 6 hours, which is in the acceptable time range. The investigation confirms that from the viewpoint of debinding, starch has a good potential as a binder component in MIM process.

A new starch-based binder for metal injection molding

A composition of starch and linear low-density polyethylene (LLDPE) was prepared as the binder and a mixture of this binder with 316L stainless steel powder was used to achieve a feedstock with 57% vol. powder loading. Rheological specifications of the binder and the feedstock were observed by means of capillary rheometery. Pseudo-plastic behavior of the binder and feedstock was investigated as a necessity in metal injection molding (MIM) process by proper flow characterization tests and their viscosity as the most significant flow characteristic was obtained in acceptable ranges. Thermogravimetric analysis (TGA) was carried out on feedstock in order to understand decomposition behavior of the binder components. In the next step, injection molding of the components was successfully conducted. Mechanical properties of compacts were then investigated through the triple point flexure test and the results showed that mechanical strength of specimens are very close to established ranges. The density of green parts was measured to assess the compaction of feedstock and it was achieved within the expected range for ferrous-based feedstocks. Debinding process was accomplished on compacted articles at three different temperature ranges including 70, 80 and 90 °C. Sintering process also was successfully accomplished on samples. For observing microstructures, the surface and cross section of specimens were compared before and after debinding as well as after sintering using scanning electron macrograph (SEM). Generally, this newly developed binder demonstrated a good potential for being utilized in MIM process.

Development of a Starch-Based Binder in Metal Injection Molding

A new starch-based binder as a natural polymer has been developed for metal injection molding (MIM). In this study tapioca starch which is cheap and readily available in Malaysia has been used as a binder which composed of starch, glycerol, linear low density polyethylene (LLDPE), citric acid and stearic acid. This developed binder system was mixed with 316 L stainless steel powder to prepare the feedstock at three different of powder loadings of 56, 57 and 58% vol. The rheological behavior of the binder and feedstock were evaluated at different temperatures using a capillary rheometer. The rheological behavior of binder shows less than 10 Pa s and the flow behavior index of the feedstocks were determined to less than 1, which indicates the flow characteristic is pseudo-plastic which is suitable for MIM process. Finally, among these three feedstocks, the feedstock of 57% vol. powder loading was selected and its viscosity values within expected shear rate range are less than 1000 Pa s.