Papers by Keyword: Foam

Abstract: The needs to replace petroleum-based polyol by bio-source polyol in polyurethane industry were increased dramatically in the last few decades. The main obstacles associating with using bio-based polyol where the change in foam density and foam shrinkage. The reacting monomer was preheated to achieve a higher maximum reaction temperature that allows more setting of the cell structure and more stable foam matrix to overcome the vacuum forces and prevent density change and foam shrinkage. A simulation code for polyurethane reaction was used to find the optimum recipes with low catalyst loading to achieve a polyurethane foam with good properties.

Abstract: In this research, effects of filler types and their loading on properties of the natural rubber closed cell foam were investigated. The azodicarbonamide was used as a blowing agent in 4 phr loading. The filler types that are the N-330 grade of carbon black, precipitated calcium carbonate and rubber grade china clay, their loading was varied from 0 to 50 phr (part per hundred dried rubber). The physical properties of the rubber foam that are the difference torque from the oscillating disk rheometer, hardness, tear strength, 300% modulus, tensile strength, elongation at break and compression set were analyzed. The results were found that the carbon black was yielded the highest of all properties in every loading. In conclusion, the suitable filler for closed cell rubber foam is the carbon black.

Abstract: A novel high-strength foam (PSA foam) was prepared by adding foaming agent in silicon-containing arylacetylene (PSA) via free heat foaming. The dispersion of foaming agent was observed by Scanning Electron Microscopy-Energy Disperse Spectroscopy (SEM-EDS) and the result indicated that the foaming agent was dispersed uniformly in PSA. The microstructure of the PSA foams prepared with different foam temperatures were characterized by SEM and the results showed the PSA foam had uniform pores when the foaming temperature was 165°C. Compressive strength of the PSA foam could reach 10.3 MPa. Furthermore, PSA foam possessed excellent thermal stability, dimensional stability and heat insulation performance: char residue reached 92.3% at 800°C under nitrogen atmosphere; the highest coefficient of thermal expansion was 83*10^-6/K; the thermal conductivity was 0.0724 W/(m•K).

Abstract: In the present work, a comparative study of the thermal performance of unfoamed and foamed geopolymers was investigated. The geopolymers were prepared by mixing fly ash with alkali activator (a mixture of sodium hydroxide and sodium silicate). The geopolymer foams were prepared by adding hydrogen peroxide (H₂O₂, 2wt.% and 4wt.%). The geopolymers were cured at room temperature (29°C) for 24 hours and at 60°C for another 24 hours. The bulk density and compressive strength decreased with increasing H₂O₂ up to 2wt.% and increased when 4wt.% of H₂O₂ was added. In order to test the thermal resistance, the geopolymers were heated at elevated temperature (200- 1000°C). Unheated geopolymers showed bulk density and compressive strength in the range of 1.6– 1.7g/cm³ and 15–17MPa, respectively. When heated up to 1000°C, the geopolymers could withstand high temperature without any disintegration and spalling. Both unfoamed and foamed geopolymers showed highest compressive strength at 200°C (17–22MPa). Further decreased in compressive strength was observed upon heating up to 800°C (10–17MPa). The compressive strength regained (14–21MPa) when heated up to 1000°C. The compressive strength was even higher than that recorded at room temperature. In the present work, unfoamed geopolymers showed overall higher thermal resistance than foamed geopolymers.

Abstract: This research studied the effect of sodium bicarbonate content on the properties of epoxy. Sodium bicarbonate (SB) was used as foaming agent to improve the properties of thermosetting epoxy resin. The samples of epoxy foam were produced using mixing method. Sodium bicarbonate was selected as blowing agent by reason of the environmental friendly and low cost concern. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15, 20 and 25 part per hundred (phr), respectively. It can be highlighted that the optimum content of the SB was selected at 15 phr and it gave the moderate porosity percentage (%), and moderate value in mechanical and density properties, higher SB content exhibited lower flexural properties.

Abstract: The repair of large bone defects is a major clinical problem for which tissue engineering (association of a biomaterial and cells) constitutes a valuable alternative. In this domain, the architecture and the mechanical properties of the 3D scaffold aimed to support cells is of key importance to succeed in bone reconstruction. In this study, we aim to design and evaluate a bionanocomposite foam-based scaffold, exhibiting all the desired biofunctional attributes of biocompatibility, bioactivity, osteoconduction/induction, combined with potential release properties. To perform this, 2 components have been associated: (i) a biopolymer, pectin, incorporating (ii) calcium phosphate nanoparticules to provide bone apatite nucleation sites, mechanical reinforcement, and to play the role of potential drug reservoir. The goal of this study was to determine the feasibility of obtention of such bionanocomposite by foam-templating, and to study the influence of mineral particules ratio on pectin foam and final scaffold 3D architecture and properties.

Abstract: Polymer blends of poly (lactic acid) (PLA) and polybutylene succinate (PBS) containing activated carbon (AC) were foamed by using Azodicarbonamide (ADC) through an extrusion process. The composite foams containing 5 phr of AC had lower density than those without AC loading for PLA:PBS ratios of 90:10, 80:20, 70:30, and 60:40. The incident of higher void fraction was the consequences of more foaming nucleation centers which were induced by adding AC in the composite foam. Maximum reduction of density by 50% with the void fraction of 50% was achieved when both ADC and AC were applied at 5 phr with the PLA:PBS ratio of 80:20. The addition of AC in composite foams enhanced the crystallization in PBS phase but had no effects on PLA crystallinity. The thermal stability of composite foams with and without AC dosages for each PLA:PBS proportion was slightly changed. For PLA-PBS blend foams, the more PLA loading there was the more tensile strength and modulus there would be. For PLA-PBS-AC composite foams, AC could improve the modulus and tensile strength of composite foams in PBS-rich samples whereas no effect on PLA-rich samples.

Abstract: The increasing demand for lightweight materials capable to absorb impact energy has driven the growth of scientific research in the metallic foams field. This paper aims to investigate the possibility to obtain Al foams from recycled aluminium alloy through the sintering dissolution process (SDP) with sodium chloride (NaCl) as space holder. Aluminium scraps from AA 3104 alloy were powdered by high energy ball milling. Alloy powder was mixed with variable weight fraction of NaCl. The mixtures were die-pressed at room temperature and then sintered at 680°C. In the following step sintered parts were immersed in boiling water to obtain the aluminium foam. Foam microstructure was characterized by scanning electron microscopy and chemical composition was analyzed by energy dispersive spectroscopy. In addition, the residual NaCl was quantified and the foam density was determined by hydrostatic method. Best result was obtained with 60 wt% of NaCl, given a relative foam density of 30%, which in turn justifies further studies with metallic foams from aluminium scraps.

Abstract: Porous aluminum can potentially satisfy both the lightweight and high-energy-absorption properties required for automotive components. In this study, functionally graded porous aluminum consisting of pure aluminum and Al-Mg-Si A6061 aluminum alloy was fabricated by a sintering and dissolution process. It was found that functionally graded porous aluminum with the same pore structures but different types of aluminum alloy can be fabricated. By performing compression tests on the fabricated functionally graded porous aluminum, it was found that its stress-strain curve initially exhibited a relatively low plateau stress similar to that of uniform porous pure aluminum. Thereafter, the stress-strain curves exhibited a relatively high plateau stress similar to that of the uniform porous A6061 aluminum alloy. Namely, it was found that the compression properties of porous aluminum can be adjusted and optimized by selecting the appropriate type of aluminum alloy.

Abstract: The development of high performance materials made from natural resources is increasing worldwide. The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. The coconut fiber can be a potential candidate to replace the industrial core and foam which its application are worldwide and it is used to increase the thickness of the fiberglass boat. In this research, three types of testing panel are constructed by using 10 mm of Coconut Fiber, 3D Core Foam and Infusion Grooved PVC Foam as the sandwich core. The resin infusion method which is produce quality final products have been used. The findings be obtained by conducting two testing methods, for the Flatwise Tensile Strength testing, the specimens taken from Coconut Fiber product yielded a higher value of strength which is 3.005 MPa compared to the specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 2.963 MPa and 1.264 MPa respectively. For the Flatwise Compressive Strength testing, the specimens taken from the Coconut Fiber product had higher value of compressive stress compared to the value of specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 29.66 MPa, 2.58 MPa and 4.68 MPa respectively. This research has proved that the Coconut Fiber is quite suitable to become as one of the laminating schedule for the construction of the fiberglass boat hull.