A study of cell nucleation in the extrusion of polypropylene foams

1997 ◽  
Vol 37 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Chul B. Park ◽  
Lewis K. Cheung
Keyword(s):  
Cell Nucleation

scholarly journals Effect of Compatibility on the Foaming Behavior of Injection Molded Polypropylene and Polycarbonate Blend Parts

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 300 ◽  
Author(s):  
Bei Su ◽  
Ying-Guo Zhou ◽  
Bin-Bin Dong ◽  
Cao Yan
Keyword(s):  
Morphological Structure ◽  
Potential Method ◽  
Grafted Polymers ◽  
Dynamic Mechanical Analyzer ◽  
Blowing Agent ◽  
Cell Nucleation ◽  
Foaming Behavior ◽  
Thermal Features ◽  
Injection Molded ◽  
Scanning Electron

To improve the foaming behavior of a common linear polypropylene (PP) resin, polycarbonate (PC) was blended with PP, and three different grafted polymers were used as the compatibilizers. The solid and foamed samples of the PP/PC 3:1 blend with different compatibilizers were first fabricated by melt extrusion followed by injection molding (IM) with and without a blowing agent. The mechanical properties, thermal features, morphological structure, and relative rheological characterizations of these samples were studied using a tensile test, dynamic mechanical analyzer (DMA), scanning electron microscope (SEM), and torque rheometer. It can be found from the experimental results that the influence of the compatibility between the PP and PC phases on the foaming behavior of PP/PC blends is substantial. The results suggest that PC coupling with an appropriate compatibilizer is a potential method to improve the foamability of PP resin. The comprehensive effect of PC and a suitable compatibilizer on the foamability of PP can be attributed to two possible mechanisms, i.e., the partial compatibility between phases that facilitates cell nucleation and the improved gas-melt viscosity that helps to form a fine foaming structure.

A Comparison of CO2 and N2 Foaming Behaviors of PP in a Visualization System

2020 ◽  
Vol 35 (5) ◽  
pp. 503-517
Author(s):  
Q.-P. Guo ◽  
J. Wang ◽  
C. B. Park
Keyword(s):  
Cell Density ◽  
Nucleating Agent ◽  
Gas Content ◽  
Experimental Conditions ◽  
Maximum Cell Density ◽  
Visualization System ◽  
Cell Nucleation ◽  
Processing Strategies ◽  
Automotive Parts ◽  
Maximum Cell

Abstract Understanding of polypropylene (PP) foaming is critically important to reduce the weight of automotive parts. In this study, we used a batch foaming simulation system with visualization cell, to observe the foaming behaviors of PP that is blown with CO2 and N2 under various experimental conditions. We found that the nucleating agent content, initial temperature, pressure (i. e., gas content), and pressure drop rate during foaming have a significant effect on cell nucleation and cell growth. The cell density and the void fraction of PP foamed with CO2 and N2, respectively, were separately observed and compared. It was found that under the same experimental conditions, the maximum cell density of PP foamed with CO2 was higher than that of PP foamed with N2. However, the maximum cell density of PP foamed with CO2 was determined to be lower than that of PP foamed with N2, when the same gas mole numbers were employed. Based on the experimental results, optimum foaming conditions and effective processing strategies for PP-CO2 system are suggested.

Solubility and diffusivity of CO2 and N2 in TPU and their effects on cell nucleation in batch foaming

2019 ◽  
Vol 154 ◽  
pp. 104623 ◽  
Author(s):  
Ruosong Li ◽  
Jung Hyub Lee ◽  
Chongda Wang ◽  
Lun Howe Mark ◽  
Chul B. Park
Keyword(s):  
Cell Nucleation ◽  
Batch Foaming

Effect of acrylonitrile–butadiene–styrene terpolymer on the foaming behavior of polypropylene

2019 ◽  
Vol 38 (3-4) ◽  
pp. 47-67 ◽  
Author(s):  
Xiao-Tian Tan ◽  
Ying-Guo Zhou ◽  
Jing-Jing Zhou ◽  
Bin-Bin Dong ◽  
Chun-Tai Liu ◽  
...  
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Suitable Candidate ◽  
Torque Rheometry ◽  
Cell Nucleation ◽  
Foaming Behavior ◽  
Thermal Features ◽  
Influence Of Crystallization ◽  
Butadiene Styrene

To improve the cellular foam structure of common polypropylene (PP), acrylonitrile–butadiene–styrene terpolymer (ABS) and compatibilizer were used to blend with PP, and the foaming behavior of PP/ABS blends was investigated. The solid and foamed samples of the PP/ABS blend with different component were first fabricated by melt extrusion followed by conventional injection molding with or without a blowing agent. The mechanical properties, thermal features, and rheological characterizations of these samples were studied using the tensile test, dynamic mechanical analyzer, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and torque rheometry. The results suggest that ABS is a suitable candidate to improve the foamability of PP. The effect of ABS and compatibilizer on the foamability of PP can be attributed to three possible mechanisms, that is, the weak interaction between phases that facilitates cell nucleation, the improved gas-melt viscosity that prevents the escape of gas, and the influence of crystallization behavior that helps to form a fine foaming structure.

scholarly journals Role of Wood Fibers in Tuning Dynamic Rheology, Non-Isothermal Crystallization, and Microcellular Structure of Polypropylene Foams

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 106 ◽  
Author(s):  
Yongming Song ◽  
Youyong Wang ◽  
Hao Li ◽  
Qiling Zong ◽  
Ailing Xu
Keyword(s):  
Isothermal Crystallization ◽  
Fiber Composite ◽  
Cell Structure ◽  
Wood Fiber ◽  
Crystallization Rate ◽  
Complex Viscosity ◽  
Expansion Ratio ◽  
Wood Fibers ◽  
Cell Nucleation ◽  
Composite Foams

Microcellular polypropylene (PP)/wood fiber composite foams were fabricated via batch foaming assisted by supercritical CO2 (scCO2). Effects of wood fibers on rheology, crystallization, and foaming behaviors of PP were comprehensively investigated. The obtained results showed that the incorporation of wood fibers increased the complex viscosity and the storage modulus of the PP matrix. Jeziorny’s model for non-isothermal crystallization kinetics indicated that wood fibers did not change the crystal growth. However, the crystallization rate of the PP matrix was decreased to a certain extent with increasing wood fiber loadings. The wood fiber exerts a noticeable role in improving the cell density and reducing the cell size, despite decreasing the expansion ratio. Interestingly, a “small-sized cells to large-sized cells” gradient cell structure was found around the wood fibers, implying cell nucleation was induced at the interface between wood fiber and PP matrix. When wood fiber loadings were specifically increased, a desirable microcellular structure was obtained. However, further increasing the wood fiber loadings deteriorated the cell structure. Moreover, the crystallinity of the composite foams initially decreased and then slightly increased with increasing wood fiber loadings, while the crystal size decreased.

Enhancing cell nucleation of thermoplastic polyolefin foam blown with nitrogen

2010 ◽  
pp. n/a-n/a ◽  
Author(s):  
S. G. Kim ◽  
J. W. S. Lee ◽  
C. B. Park ◽  
M. Sain
Keyword(s):  
Cell Nucleation ◽  
Thermoplastic Polyolefin

Correlation of Decompression Time and Foaming Temperature on the Cell Density of Foamed Polystyrene

2005 ◽  
Vol 24 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Keiichi Muratani ◽  
Minoru Shimbo ◽  
Yasushi Miyano
Keyword(s):  
Cell Growth ◽  
Temperature Dependence ◽  
Cell Density ◽  
Saturation State ◽  
Foaming Agent ◽  
Decompression Rate ◽  
Cell Nucleation ◽  
Cell Densities ◽  
Foaming Temperature ◽  
Decompression Time

In this paper, the correlation between the foaming temperature and the decompression rate (decompression time) of the cell density that is the number of cells per unit volume remaining in the foamed plastic will be discussed. Foaming was carried out by the following method: the blowing agent was soaked into the resin as a solid state at high pressure under temperatures higher than the glass transition temperature of the resin. After the foaming agent reached its saturation state, cell nucleation and cell growth were accelerated by decompression. Finally, cell growth was halted by cooling. A device that can accurately control temperature and the decompression rate was designed, produced and verified for accuracy prior to this investigation. The polystyrene (PS) specimens were foamed under various foaming temperatures and the decompression rates using the above-mentioned method. The following results were obtained: 1. Cell density of foamed polystyrene shows time and temperature dependence as follows. The cell density increases when the decompression rate is quick, i.e. the decompression time is shortened under the condition of low foaming temperature, and cell density decreases when the decompression rate is slow, i.e. decompression time is lengthened under the condition of high foaming temperature, 2. Correlation is maintained between the temperature dependence and time dependence of the cell density of foamed PS, and it can be expressed by one master curve, 3. Based on this correlation, it is possible to predict the required foaming conditions of plastics having arbitrary cell densities.

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