Polypropylene/Waste Ground Rubber Tire Powder Foams: A Study of the Relationship Between Processing and Structure Using Supercritical Carbon Dioxide

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhen Xiu Zhang ◽  
Shu Ling Zhang ◽  
Zhen Xiang Xin ◽  
Jin Kuk Kim
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Cell Size ◽  
Statistical Experimental Design ◽  
Foam Density ◽  
Processing Conditions ◽  
Rubber Tire ◽  
Ground Rubber ◽  
The Relationship ◽  
Supercritical Carbon

AbstractIn this study, processing-structure relationships in polypropylene (PP)/waste ground rubber tire powder (WGRT) foams made using supercritical carbon dioxide as a physical blowing agent were investigated. In order to investigate the relationship between structure and properties of PP/WGRT foams, it was necessary to make samples with a wide range of controlled structures. For this reason, a systematic investigation of the relationship between processing conditions and structure was performed based on a statistical experimental design. Regression analysis was conducted on the data and expressions were developed to quantify the relationships between structural parameters and processing conditions. The samples were saturated with carbon dioxide at high temperature and high pressure and the saturated specimens were expanded during the pressure-quench process. The importance of the individual processing parameters was determined. Statistical analysis of data showed that saturation temperature was the most important factor determining cell size, cell density and relative density. By controlling the foaming conditions, PP/WGRT samples having the same foam density and different cell size or having the same cell size and different foam density were produced.

Preparation and characterization of polypropylene/waste ground rubber tire powder microcellular composites by supercritical carbon dioxide

2008 ◽  
Vol 16 (5) ◽  
pp. 404-410 ◽  
Author(s):  
Zhen Xiu Zhang ◽  
Sung Hyo Lee ◽  
Jin Kuk Kim ◽  
Shu Ling Zhang ◽  
Zhen Xiang Xin
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Rubber Tire ◽  
Ground Rubber ◽  
Supercritical Carbon

scholarly journals Supercritical Carbon Dioxide (scCO2) Extraction of Phenolic Compounds from Lavender (Lavandula angustifolia) Flowers: A Box-Behnken Experimental Optimization

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3354 ◽  
Author(s):  
Katarzyna Tyśkiewicz ◽  
Marcin Konkol ◽  
Edward Rój
Keyword(s):  
Carbon Dioxide ◽  
Phenolic Compounds ◽  
Supercritical Carbon Dioxide ◽  
Extraction Method ◽  
Positive Influence ◽  
Total Phenolic ◽  
Statistical Experimental Design ◽  
Lavandula Angustifolia ◽  
Phenolic Contents ◽  
Supercritical Carbon

Due to their numerous health benefits associated with various diseases and anti-oxidation properties, the phenolic compounds collectively referred to as phytochemicals have attracted a lot of interest, however, a single extraction method for polyphenols has not been developed yet. Supercritical fluid extraction, a green extraction method, provides the final product without organic solvent residues. In this work the extraction of lavender was performed using supercritical carbon dioxide. A statistical experimental design based on the Box-Behnken (B-B) method was planned, and the extraction yields and total phenolic contents were measured for three different variables: pressure, temperature and extraction time. The ranges were 200–300 bar, 40–60 °C and 15–45 min. The extracts yields from scCO2 extraction were in the range of 4.3–9.2 wt.%. The highest yield (9.2 wt.%) was achieved at a temperature of 60 °C under the pressure of 250 bar after 45 min. It also corresponded to the highest total phenolic content (10.17 mg GAE/g extract). Based on the study, the statistically generated optimal extraction conditions to obtain the highest total phenolic compounds concentration from flowers of Lavandula angustifolia were a temperature of 54.5 °C, pressure of 297.9 bar, and the time of 45 min. Based on the scavenging activity percentage (AA%) of scCO2 extracts, it is concluded that the increase of extraction pressure had a positive influence on the increase of AA% values.

Cell characteristics of epoxy resin foamed by step temperature-rising process using supercritical carbon dioxide as blowing agent

2016 ◽  
Vol 54 (2) ◽  
pp. 359-377 ◽  
Author(s):  
Jiaxun Lyu ◽  
Tao Liu ◽  
Zhenhao Xi ◽  
Ling Zhao
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Epoxy Resin ◽  
Cell Size ◽  
Cell Density ◽  
Diglycidyl Ether ◽  
Bubble Nucleation ◽  
Blowing Agent ◽  
Curing Reaction ◽  
Supercritical Carbon

A temperature-rising batch foaming process with supercritical carbon dioxide (ScCO2) as blowing agent was used to prepare epoxy resin foams consisting of diglycidyl ether of bisphenol A and m-xylylenediamine. The dissolution and diffusion behaviors of CO2 in pre-cured epoxy resin were investigated, as well as the parameter effect of CO2 saturation step and foaming step on the cell characteristics. It was proved that closed-cells could be generated for CO2 unsaturated samples and the cell characteristics with the same dissolved CO2 concentration were similar. The merged and cracked bubble morphologies were usually obtained for CO2-saturated epoxy resin samples. With increasing CO2 concentration from 0.021 g CO2/g epoxy resin to 0.061 g CO2/g epoxy resin in the unsaturated samples, the cell size increased from 170.2 µm to 262.6 µm and the cell density decreased from 6.8 × 105/cm3 to 3.1 × 105/cm3. Bubble nucleation and growth occurred simultaneously with curing reaction in temperature-rising step. As the final foaming temperature increased from 60℃ to 120℃, the cell size of samples with dissolved CO2 concentration of 0.021 g CO2/g epoxy resin increased from 172.7 µm to 369.0 µm, while the cell density first increased from 6.8 to 7.3 and then decreased to 3.5. The cell size of samples with CO2 concentration of 0.031 g CO2/g epoxy resin increased from 145.3 µm to 180.5 µm with foaming time from 5 min to 20 min, but changed slightly when curing reaction almost finished and CO2 was depleted after 20 min.

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