Papers by Keyword: Blowing Agent

Abstract: In this study, various NR:EPDM:EVA rubber foams were prepared. The ratios of NR:EPDM:EVA were at 50:20:30 and 50:10:40. The amounts of blowing agent, dinitrosopentamethylenetetramine (or Supercell DP) were 5, 6, and 7 part per hundred of rubber (phr). The vulcanizing agent, dicumyl peroxide (or DCP) loadings were at 0.7 and 1 phr. The influence of rubber formula on the performance of the obtained rubber foam was discussed here. The results showed that increasing EVA proportion and Supercell DP loading and decreasing DCP loading led to the decrease in density, thus giving the lower thermal conductive rubber foam which was suitable for using as an insulating ceiling board. However, the above condition gave the rubber foam with slightly inferior mechanical properties including lower hardness and higher % compression set.

Abstract: The properties of natural rubber foam filled with bagasse fiber of varying content (0-50 phr) and different blowing agent content (5 and 8 phr) were investigated, with rubber compounds and vulcanized rubber also examined. Rubber compound properties included measurements of scorch time, cure time, minimum torque, maximum torque, density, and percentage of expansion in the mold. When bagasse fiber and blowing agent content increased, the maximum torque value of the compounded rubber increased. For rubber compound with blowing agent loading at 5 phr, cure time increased with an increasing bagasse fiber content of 40-50 phr, while scorch time and density of the rubber compound remained unchanged. The percentage of rubber compound expansion in the mold decreased with increasing bagasse fiber content. The cell size of natural rubber foams was inspected using an optical microscope. Small and homogeneous cell size was found in natural rubber foam with blowing agent content of 8 phr and higher bagasse fiber content. The incorporation of bagasse fiber enhanced the compressive strength of the natural rubber foam. Vulcanized rubber properties such as the modulus at 100% strain, tensile strength, and strain at break were also studied. The modulus increased, whereas stress at break and strain at break decreased with increasing bagasse fiber content. On the other hand, tensile strength and strain at break increased with increasing blowing agent loading.

Abstract: In this research developed the technique for the metal foam based on the Al-carbon nanotubes composite material. The optimal regimes for the samples foaming are proposed. The pilot samples were received. The behavior of the pores distribution in the samples volume is presented.

Abstract: We report on the rigid polyurethane foam (RPUF) with varying amount of blowing agent. The effects of blowing agent in the formation of polyurethane will be characterized using scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy. SEM images revealed that varying the amount of blowing agent will significantly change the surface morphology of the resulting RPUF. The average cell size of the RPUF increases with increasing amount of blowing agent. Moreover, FTIR results revealed the presence of functional group related to formation of urethane bonds such as N-H, C=O, C=N and C-O-C stretching suggesting that polyurethane foam was successfully synthesized. This simple and straightforward process of RPUF using water as blowing agent will be economical.

Abstract: PLA is a bio-based biodegradable plastic, which has excellent biocompatibility and biodegradability. Because the mechanical properties of microcellular foaming material is similar to petroleum-based plastics (PS), PLA foams have been considered as ideal alternative materials. However, PLA has several inherent drawbacks such as low melt strength and slow crystallization kinetics, which severely inhibit the PLA foaming process to produce high-density forms and uniform cell morphology. By adding a chain extender or nanoparticles, and blending with other biological materials, these ways could effectively enhance the expansion ratio and the cell density of PLA and improve the mechanical properties of PLA foams. The most current investigations on microcellular foaming of PLA were reviewed in the article, and outlook of PLA foams was raised.

Abstract: The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO₃) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO₃ at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO₃ addition.

Abstract: Use calcium carbonate, sodium carbonate and barium carbonate as blowing agent, polyethylene glycol as binder,Cr₂O₃ as nucleating agent,TiO₂ as nucleating agent,CaF₂ as a flux in glass powder, we can produce porous glass-ceramics, and after above research, the apparent density, powder density, porosity, the main phase, microscopic characteristics and thermal performance of the samples would be test. The results show that: considering the physical and mechanical performance of porous glass-ceramics, the froth effect of sodium carbonate is most ideal. When the dosage is 6%, the apparent density is minimum, the porosity is maximum and the thermal conductivity is maximum and the main phase is wollastonite.

Abstract: Influences of foaming temperature (i.e. 150 and 160^OC) and blowing agent content on cure characteristics, mechanical and morphological properties of natural rubber (NR) foams were investigated. The blowing agent used in this study was oxybis (benzene sulfonyl) hydrazide (OBSH). The expandable rubber samples were prepared using a conventional compression molding technique via a heat transfer foaming process and an air-circulating oven. For cure behavior, it was found that maximum torque and torque difference tended to decrease with increasing the OBSH content for both processing temperatures. Decreasing of cure time was observed at 3 phr of the OBSH content and then it tended to increase. Moreover, cure time and scorch time decreased with increasing foaming temperature. As a result, the NR foam with large cell size and non-uniform foam cell distribution was observed. Mechanical properties of the NR foam in a term of hardness gradually decreased upon increasing the OBSH content. Whilst compression set increased with increasing the OBSH content up to 6 phr after that it decreased.

Abstract: In this paper the environment protection type blowing agent replacement process had been briefly introduced. Experimental study had been conducted on the burning and thermal insulation performance of the traditional CFC-11 (Freon) and typical environment-friendly blowing agent, and the influence rules of density and gas phase thermal conductivity on the main performance were obtained

Abstract: ncreasing environmental awareness has led to an increase in the usage of wood plastic composites in many countries. The primary objective of this research was the decrease in the density of wood particle-polypropylene composites using chemical blowing agents while retaining their mechanical properties. Different amounts of Azodicarbonamide (0%, 1% and 2% by weight) were mixed with four blends consisting of wood particles (15%, 25%, 35% and 45% by weight), Epolene (2% by weight) and polypropylene and compounded in an extruder. The resulting extrudates were granulated, injection-moulded into specimens and tested for density, tensile strength and impact strength. The secondary objective of this research was the increase in the electrical conductivity of wood particle-polypropylene composites using conducting agents for novel end usages. Different amounts of carbon black (1%, 3%, 5%, 7% and 10% by weight) were mixed with a blend consisting of wood particles (45% by weight), epolene (2% by weight) and polypropylene and compounded in an extruder. The resulting extrudates were granulated, compression-moulded into plates, machined into specimens and tested for electrical conductivity and tensile strength.