Papers by Keyword: Foaming

Abstract: The foamed plastics are not bio-degradable and not readily recyclable. How to substitute new foamed buffer materials with lower pollution for foamed plastics became a popular research topic. The paper discussed the effects of microwave power, natural bonding agent, lubricating agent and crosslink agent on foamed buffer material with fibers of old newspaper and inorganic foaming agent. The result showed that increasing of microwave power could be beneficial to decrease the molded time and density of foamed buffer material with fibers of old newspaper. The best foamed properties were achieved with proper dosage of natural bonding agent like wheat flour, glyceryl monostearate sodium borate at the microwave power of 575W.

Abstract: Dried Red mud slurry was ground to small powders. It was then mixed with waste glass and dolomite powders. The mixtures with different amounts of red mud and dolomite were pressed to form green bodies, which were foamed at high temperatures. To achieve a good foaming effect, the content of red mud is 35~45% in the batch and 10wt% of dolomite should be added as the foaming agent. It is found that the best foaming temperature is 1130°C, much higher than the decomposition temperature of the pure dolomite. The best obtained product has an apparent density, bending strength of 0.896g/cm³ and 9.7MPa, respectively. X-ray measurement results indicate that the red mud has reaction with the other raw materials used in the green body. The crystalline phase formed in the sample is augite. The present study provides a simple way to directly foam a mixture containing red mud to form useful glass-ceramics.

Abstract: In this work, polystyrene/ graphene nanocomposite foams were prepared using supercritical carbon dioxide. Chemically reduced graphene oxide were incorporated into PS using latex mixing. Subsequently, the nanocomposites were foamed with supercritical CO2, the foaming temperature is varied. The morphology and electrical properties of the foamed samples were discussed. It is suggested that foaming temperature has significant influence on the morphology of foams. For those samples foamed at higher temperature, foams have thin cell wall and low density even when the content of graphene is relatively high, while they possess good electrical conductivity, may be used as light weight functional materials.

Abstract: The processing of PPC/wood fiber foam composites using moisture as blowing agent was studied in this manuscript. Three important factors, such as: moisture content, wood fiber content and extruder die temperature were investigated with orthogonal design. The relationship between each factor and foam density was revealed, as well as the foaming mechanism was obtained.

Abstract: The aim of this work is to study controllability of cell structure of foam by a Polypropylene (PP)/Polystyrene (PS)/ Polymethyl methacrylate (PMMA) ternary polymer blend. The effects of different polymer matrix, its blend morphology, and rheology on the cell structure of the ternary blend foam were investigated. The batch pressure quenched foaming of the ternary blend with supercritical carbon dioxide (CO₂) was conducted in the temperature range from 60 to 160°C for PP matrix and 60 to 140°C for PS and PMMA matrices to observe the controllability of bubble location and size. The experimental results showed that interfacial tension, foaming temperature, and viscoelasticity are the important factors to control the cellular structure in ternary blend system.

Abstract: General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS) were foamed with supercritical carbon dioxide in the batch foaming process. Foaming behaviors of GPPS and HIPS were investigated. The cell diameters and cell densities of GPPS and HIPS vary strangely with foaming conditions and can be explained by the classical nucleation. The competition between cell growth and cell nucleation is used to explain these strange foaming behaviors. The glass transition temperature (Tg) almost remains constant with the foaming temperature rising.

Abstract: Electrical properties and morphology of carbon black (CB) filled ethylene-butyl-acrylate copolymer (EBA) composites were studied in compact and chemically foamed versions. Conductivity percolation threshold for foamed composites was lowered by five weight percent of carbon black concentration. It means that the same conductivity values were achieved at reduced concentration of filler than for non-foamed version of composite. As a result semiconducting material with reduced density (weight) and content of carbon black is obtained. The sensitivity of foamed composite conductivity to mechanical stimulus induced by uniaxial compression was observed.

Abstract: Hemp haulm is processing residues extracted after the hemp fiber, with wide raw material sources, cheap price, light quality, good fiber shapes, good toughness, high strength and good buffer performance. In order to develop the application field of hemp stalk processing residues, cushioning packaging materials were prepared using hemp haulm as raw material with the hybrid inorganic foaming agent and corn starch adhesive by microwave foaming method. The properties including density, foam distribution and static compressive properties of this material were analyzed. The experimental results indicated that the density of hemp haulm foaming cushioning packaging materials was 0.235-0.339g/cm3, cell numbers were 14-25.5/cm2, and rebound rate was 62.2%-93.1%. The major influence factors on the properties of hemp haulm foam material were the particle size, foaming agent and adhesives, etc. Research showed while the hemp haulm diameter was small, the ratio of hemp haulm power and starch was 1:0.4 and starch with polyvinyl alcohol (PVA) was 1:0.5, the materials had good buffer performance. When the ratio of compound foaming agent(sodium bicarbonate, ammonium bicarbonate, ammonium carbonate)was 1:2:1, the material had the best cushioning properties as well as higher strength. Compared with polyethylene (EPE) and polystyrene (EPS), the hemp foam material was harder than EPS with no obvious yield point, no material collapsing and good cushioning properties. When the stress was greater than 5-15 N/cm2, the cushioning property of the hemp haulm foaming material was better than EPE, but close to EPS.

Abstract: In order to reduce energy costs, light-weight alumina-spinel refractories with tri-modal pores were prepared by foaming process. The influence of foaming agent and magnesia on the properties of light-weight alumina-spinel refractory was investigated. The rheology of the original slurry and the density, mechanical properties and microstructure of samples were evaluated. The results showed that light-weight alumina-spinel refractory contained a highly interconnected network of spherical cells, consisting of the large-sized cells (larger than 40 um), moderate-sized pores( averaging about 20 um) and small-sized voids, which mainly attributed to the foaming agent and in-situ formation of spinel. The cold compressive strength of the samples varied within the range of 2-12MPa, corresponding to densities of 0.8~1.2g/cm3,and the thermal conductivity changed from 0.273W/(m•K) to 0.315 W/(m•K) at the 500 °C. It was found that the density of the sintered samples was dependent both on the content of foaming agent and magnesia. With the help of magnesia, light-weight alumina-spinel refractories with good volume stability were prepared by foam method.

Abstract: A novel nonflammable thermal insulation material for buildings was prepared by foaming sodium silicate solution with blowing agent. The material density is 274 kg/m3,with the compressive strength up to 2.0MPa and the coefficient of heat conductivity low to 0.08 W/ m•K.