Papers by Keyword: Foaming

Abstract: Foamed composites of polypropylene containing bamboo powder were prepared using an injection moulding process. Measurement of density, flexural, tensile and notched impact properties of the prepared composites was carried out. Water absorption of the composites was investigated. The rheological behavior of composites was also investigated by rotary rheometer. The density of microfoamed composites was reduced by about 14%.When the bamboo powder was 50 phr (33.3% by weight), the integrated property was best ; the density was 0.886 g·cm^-3 and the flexural, tensile and notched impact strength were 58.72 MPa, 30.86 MPa and 5.246 KJ·m^-2 respectively; and the thickness swelling and water absorption were 1.31% and 0.7% after duration of 240 h. The results pointed out the composites showed a flow behavior of pseudoplastic fluid; the storage modulus and loss modulus increased and loss tangent decreased with the increase of bamboo powder content. The composite had a typical shear thinning characteristic and the complex viscosity increased with the content of bamboo powder increased.

Abstract: The residues from wheat straw pulping mainly include uncooked chips and fiber bundles. In order to achieve high quality pulp, the residues require removal from the system. It was not necessary that the residues were re-cooked because of its high contents of non-cellulosic constituent. The achievement of low density foamed buffer material with the residues of wheat straw pulping would make the second pollution problem of the residues be solved, and achieve a replacer of foamed plastic material. The paper discussed the producing techniques of foamed buffer material with the residues of wheat straw pulping. The result showed that the best foamed properties of the residues were achieved with proper dosage of natural bonding agent like wheat flour, inorganic foamed agent, crosslink agent, and proper foamed temperature. The density and compression of foamed buffer material with the residues of wheat straw pulping were achieved with 60 kg /m³ and 60 kPa respectively at the optimum foaming condition.

Abstract: The new type of cushion packaging material that took wood fiber and starch as raw materials was investigated in this paper. Through compression molding, the effects of some parameters on material’s mechanical properties were studied to optimize the technical process, including the ratio of wood fiber to starch, the content of adhesive and foaming agent. Using DPS data processing system for Second-order Polynomial Stepwise Regression to analyze the effects of the different process parameters on the properties and establish mathematical model, so as to optimize the experimental program and ascertain the best conditions, at the same time to verify it. The results show that the ratio of wood fiber to starch is 1:2, 6% AC foaming agent, and 10% polyvinyl alcohol are the optimum parameter.

Abstract: In order to decrease the deadweight of structures and/or increase thermal and acoustic insulation properties, the most widely used material for the preparation of concrete is lightweight aggregate processed either from naturally occurring lightweight materials or waste materials. The present paper presents a methodology for the production of light-waste aggregate (LWA). Waste glass, silica sludge, clay, and polishing residue were studied as potential raw materials. There are two different mechanisms active in the process of LWA production; one is combustion of organic residue in clay matrix, resulting in porous structure, the other one is a foaming process, applicable to glassy matrix where a selected foaming agent degasses at elevated temperature, and the resulting gasses remain trapped in the glassy structure. In the presented case, paper mud served as poreforming agent whereas MnO2 and SiC were added as foaming agents. The emphasis of this study was placed on finding suitable additives for lowering the softening temperature and thus facilitating the foaming process. It was found that the addition of polishing residue from the polishing process of granite–like stone lowered the softening point of the clay and silica sludge. Depending on mixture composition and regime of firing, lightweight aggregates with densities between 0.5 and 2.0 g/cm3 were obtained and analyzed.

Abstract: Carbon foam with relatively high compressive strength and high porosity was prepared from a mixture of mesophase pitch and Si particles by foaming and carbonization. The influence of Si content on the microstructures and properties of the carbon foam was studied. Results show that the pore number decreases and the strut thickness increases with an increasing of Si content. In addition, bulk density also increases with increasing Si content but the porosity decreases. Si addition to the mesophase pitch reduces the number of microcracks on the cell wall of the carbon foam remarkably which results in an increase of compressive strength for the carbon foams. Compressive strengths improve by 46%, 176% and 339% at Si additions of 30%, 40% and 50% (wt %), respectively. Carbon foam with a relatively high compressive strength of 24.6 MPa and a porosity of 61% are obtained when 50 wt% Si is added.

Abstract: Mayor advances have been made in the field of halogen-free flame retardant composites in the last years, mainly due to increasing regulatory pressures. This paper focuses in aluminium trihydroxide (ATH) as the halogen-free flame retardant and low density polyethylene (LDPE) as the polymer matrix of the fire retardancy foam. The attempt of this article is to achieve a cellular structure by foaming these materials, when high loading levels (up to 60wt %) of ATH are introduced. This is a difficult task due to the high amount of filler in the formulation. The aim is to reduce density without losing thermal and mechanical properties. In order to characterize the cellular structure as well as the thermal, mechanical and combustion properties, a complete study of the foamed samples was made by means of scanning electronic microscopy (SEM), thermogravimetric analysis (TGA), melt flow index (MFI), air pycnometry, mechanical testing at low strain rates, limiting oxygen index (LOI) and calorimeter bomb tests.

Abstract: In-line oxygen sensors have been developed for the glass melt and for the float bath. Glass melt oxygen sensors are used for the continuous monitoring of the oxidation state (or redox) of the glass melt and are very important for the control of many glass melt and glass product properties such as radiative heat transfer, fining, foaming, forming and optical characteristics. Too high oxygen levels in the float bath can be prevented by using both oxygen sensors in the tin melt and the atmosphere above it. Oxygen related defects on the glass sheet surface such as dross, tin pick-up, bloom and tin drips are reduced or even prevented. Moreover, expensive hydrogen gas can be saved by a more effective dosage.

Abstract: Lightweight aluminum foams are attractive energy absorbing material for automotive machines. Strength of aluminum foams manufactured through casting process is not so much high as dense aluminum alloys due to difficult alloying. Ductility of aluminum foams manufactured through powder metallurgical process is low due to fine oxide dispersions. In this paper, we introduce new metallic foam having excellent energy absorbing property. Closed-cell Zn-22 mass%Al eutectoid alloy foams are manufactured through powder metallurgical process. The Zn-22Al alloy is known as typical superplastic material and shows superplastic deformation below 523 K, even at room temperature. Using titanium hydride powder as a foaming agent, the porosity as high as 60% is achieved. Solution treatment followed by quenching causes ductile compressive deformation at room temperature. In addition, the absorbed energy of the Zn-22Al foams are much larger than those of conventional aluminum foams.

Abstract: Al-Mg alloy foams were synthesized via conventional melt foaming method. Ca and TiH2 were introduced into molten Al-Mg alloys with different magnesium contents. The macrostructures of resultant alloy foams were analyzed and correlated with compressive properties estimated by compression test. It is shown that the pore structures observed in alloy foams degraded with increasing Mg contents. This tendency was shown to be consistent with compressive characteristics of corresponding alloy foams. In detail, plateau strength was high for Al-1wt%Mg alloy foams, exhibiting a gradual decrease in plateau strength with increasing magnesium content.