Microcellular Foaming of Biodegradable PLA/PPC Composite Using Supercritical CO2

2016 ◽  
Vol 861 ◽  
pp. 247-252
Author(s):  
Zhen Guo Ma ◽  
Xian Hua Lang ◽  
Peng Luo ◽  
Zhen Xiang Xin ◽  
Zhen Xiu Zhang
Keyword(s):  
Cell Structure ◽  
Saturation Pressure ◽  
Saturation Temperature ◽  
Poly Lactic Acid ◽  
Foam Density ◽  
Foaming Process ◽  
Composite Foams ◽  
Controlled Structure ◽  
Poly Propylene ◽  
Foaming Temperature

Poly (lactic acid) (PLA)/poly (propylene carbonate) (PPC) composite foams were microcellular foamed with CO2 through a batch foaming process. The influences of PPC contents, foaming temperature, and saturation pressure on the cell structure and foam density were investigated. The biodegradable PLA/PPC composite foam showed a controlled structure of microcellular and nanocellular. With an increase in saturation temperature and pressure, the cell size was increasing and both the cell density and foam density were decreased simultaneously.

Effect of rare earth nucleating agent on supercritical CO2 foaming behavior of block copolymerized polypropylene

2021 ◽  
pp. 026248932110536
Author(s):  
Yun Zhang ◽  
Yadong He ◽  
Chunling Xin ◽  
Yanbin Su
Keyword(s):  
Rare Earth ◽  
Saturation Temperature ◽  
Nucleating Agent ◽  
Expansion Ratio ◽  
Good Effect ◽  
Cell Diameter ◽  
Average Cell ◽  
Foaming Process ◽  
Foaming Temperature ◽  
Crystal Content

The rare earth nucleating agent was used to modify block copolymerized polypropylene (PPB) in foaming process. The results show that the crystallization of PPB and the melting temperature of β-crystal increased gradually with increased β-crystal nucleating agent content. The total crystallinity decreased with amount of addition increasing, and the relative content of β-crystal increased first and then decreased. When β-crystal nucleating agent content was 0.4 wt%, the relative β-crystal content reached the maximum value of 95.27%, and the final crystal grain refinement significantly. The addition of rare earth β-crystal nucleating agent has a good effect on improving the uniformity of foam cells. Under the same content of β-crystal nucleating agent and pressure, the average cell diameter and expansion ratio increased with the saturation temperature increasing. After the foaming temperature reaches 155°C, the expansion ratio began to decrease, which was also consistent with the changed trend of relative β-crystal content. At the same content of temperature and relative β-crystal, as the foaming pressure increased, the cell diameter decreased gradually, and the expansion ratio increased first, and then decreased.

Controlled foaming of polycarbonate/polymethyl methacrylate thin film with supercritical carbon dioxide

2016 ◽  
Vol 30 (12) ◽  
pp. 1713-1727 ◽  
Author(s):  
Yuanxiang Luo ◽  
Yajun Ding ◽  
Changchun Wang ◽  
Linghua Tan ◽  
Sanjiu Ying
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Polymethyl Methacrylate ◽  
Saturation Pressure ◽  
Saturation Temperature ◽  
Mean Diameter ◽  
The Mean ◽  
Foaming Temperature ◽  
Supercritical Carbon ◽  
Foaming Time

The polycarbonate (PC)/polymethyl methacrylate (PMMA) (10/90) blends with microcellular foams were prepared by the two-step process using supercritical carbon dioxide as physical foaming agent. The effects of saturation temperature, saturation pressure, foaming temperature, and foaming time on the cell morphology structure were investigated by scanning electron microscopy. The results indicated that the mean diameter of cells in foamed PC/PMMA films decreased with the increment of saturation temperature and saturation pressure but increased with the increment of the foaming time. Moreover, the mean diameter of cells decreased first, but then increased with the increment of the foaming temperature. The cell density ( Nc) increased with the increment of saturation temperature and saturation pressure but decreased with the increment of the foaming time. However, the Nc increased first but then decreased with the increment of the foaming temperature.

scholarly journals Composite Foams Prepared through Hollow Glass Microspheres Assisted Bubbling

2013 ◽  
Vol 22 (1) ◽  
pp. 096369351302200
Author(s):  
Zhenguo An ◽  
Jingjie Zhang
Keyword(s):  
Heat Insulation ◽  
Cell Structure ◽  
Nucleating Agent ◽  
Glass Microspheres ◽  
Insulation Property ◽  
Hollow Glass Microspheres ◽  
Hollow Glass ◽  
Foaming Process ◽  
Composite Foams ◽  
Ammonium Hydrogen

Composite foamy structures were prepared through hollow glass microspheres (HGM) assisted bubbling of silicone rubber with ammonium hydrogen carbonate as the blowing agent. The presence of HGM not only favoured the foaming process (acted as nucleating agent for the formation of minute bubbles at the initial stage of the bubbling), but also bring heterogeneous close-cell bubbles with stable inorganic shells into the foamy structure, which played an important part in the improvement of the heat insulation property of the product. Compared to the foamy structures without HGM, The composite foamy structures possessed improved heat insulation and sound absorbing properties. This work provides an additional strategy to fabricate composite foams with tailored cell structure and properties.

Preparation Method and Device of Microcellular Sheet Based on Batch Foaming

2015 ◽  
Vol 1095 ◽  
pp. 495-500
Author(s):  
Xin Xiao ◽  
Xue Tao He ◽  
Yu Mei Ding ◽  
Liu Qin ◽  
Wei Min Yang
Keyword(s):  
Preparation Method ◽  
Saturation Pressure ◽  
Saturation Temperature ◽  
Control Parameters ◽  
Control Temperature ◽  
Bubble Density ◽  
Three Stages ◽  
Harmful Substances ◽  
Two Parameters ◽  
Foaming Temperature

This paper mainly introduces a new method of preparation of microcellular material, this method can be divided into three stages: kettle with saturation pressure, heating foaming, flattening and calendaring. During the process of supercritical CO2saturated, different materials need reasonable control parameters such as saturation pressure, saturation temperature and saturated time, and the values of saturation temperature and saturation pressure will directly affect the permeability of supercritical CO2. During the process of heating foaming, it needs to strictly control the parameters such as foaming temperature and foaming time, because the bubble density and bubble size are closely related to the two parameters. During flattening and calendaring process, it is important to control temperature and speed of roller reasonably to avoid the phenomena of collapse in bubbles. There are no harmful substances emissions using this method to produce ultrathin microcellular material, which can also protect the environment.

Solid-State Foaming of Polycaprolactone (PCL)

2007 ◽  
Author(s):  
Hai Wang ◽  
Wei Li ◽  
Vipin Kumar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solid State ◽  
Room Temperature ◽  
Saturation Pressure ◽  
Crystalline Polymer ◽  
Foaming Process ◽  
Quenching Process ◽  
Foaming Temperature ◽  
Scanning Electron

Polycaprolacton (PCL) is a synthetic biodegradable polymer that is widely used in tissue engineering related studies. It is a semi-crystalline polymer, and has a glass transition temperature (Tg) of −60°C and a melting temperature of 60°C. In this paper, we report on the progress in creating porous PCL foams using the solid-state foaming process. The objective of this study is to examine the foam-ability of PCL using room temperature saturation. PCL specimens were made using compression molding. A “quenching” process was introduced to manipulate the crystallinity of PCL samples. CO2 was used for gas saturation. The effects of saturation pressure and foaming temperature were studied. The created microstructures were characterized using scanning electron microscopy (SEM). The preliminary results have shown that microstructures with pores on the scale of hundreds of nanometers were generated.

scholarly journals SPECIALTY NATURAL RUBBER LATEX FOAM: FOAMABILITY STUDY AND FABRICATION PROCESS

2021 ◽  
Author(s):  
Roslim Ramli ◽  
Ai Bao Chai ◽  
Jee Hou Ho ◽  
Shamsul Kamaruddin ◽  
Fatimah Rubaizah Mohd Rasdi ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Cell Structure ◽  
Natural Rubber Latex ◽  
Fabrication Process ◽  
Gelling Agent ◽  
Foam Density ◽  
Foaming Process ◽  
Automotive Parts ◽  
Gelling Time ◽  
Stability Time

ABSTRACT Specialty natural rubber (SpNR) latex, namely, deproteinized natural rubber (DPNR) latex and epoxidized natural rubber (ENR) latex, has been produced to meet specific product's requirements. However, SpNR is normally used in the form of block rubber to manufacture dry rubber products such as tires and automotive parts. The applications of SpNR latex into latex foam products will be diversified. Findings indicate that foamability of SpNR latex is lower compared to normal latex (LATZ) but shows longer stability time after foamed. Findings also indicate that foam collapse and foam coagulate are two main challenges in the fabrication process of SpNR latex foam. Despite these challenges, SpNR latex foam can be fabricated at different density levels. During the foaming process, additional foaming agent is required to fabricate a SpNR latex foam, which is different from fabricating a normal NR latex foam, especially at low latex foam density. Consequently, a higher level of sodium silicofluoride, used as the gelling agent, is required to set the cell structure of the foam. Findings also indicate that foam density influenced the gelling time and volume shrinkage of the SpNR latex foam. An ideal compounding, foaming, and gelling formulation to fabricate SpNR latex foam via Dunlop batch foaming process has been developed. Morphological study showed that all latex foams are open-cell structure, with lower density foam exhibiting higher porosity and mean pore size. Comparison on hysteresis behavior between DPNR and ENR latex foam indicated that ENR latex foam exhibits higher hysteresis loss ratio compared to DPNR latex foam.

scholarly journals Compression Molding of Thermoplastic Polyurethane Foam Sheets with Beads Expanded by Supercritical CO2 Foaming

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 656
Author(s):  
Tao Zhang ◽  
Seung-Jun Lee ◽  
Yong Hwan Yoo ◽  
Kyu-Hwan Park ◽  
Ho-Jong Kang
Keyword(s):  
Cell Size ◽  
Supercritical Co2 ◽  
Cell Structure ◽  
Thermoplastic Polyurethane ◽  
Compression Molding ◽  
Expansion Ratio ◽  
Compression Pressure ◽  
Elongation At Break ◽  
Foaming Process ◽  
Foaming Temperature

Expanded thermoplastic polyurethane (ETPU) beads were prepared by a supercritical CO2 foaming process and compression molded to manufacture foam sheets. The effect of the cell structure of the foamed beads on the properties of the foam sheets was studied. Higher foaming pressure resulted in a greater number of cells and thus, smaller cell size, while increasing the foaming temperature at a fixed pressure lowered the viscosity to result in fewer cells and a larger cell size, increasing the expansion ratio of the ETPU. Although the processing window in which the cell structure of the ETPU beads can be maintained was very limited compared to that of steam chest molding, compression molding of ETPU beads to produce foam sheets was possible by controlling the compression pressure and temperature to obtain sintering of the bead surfaces. Properties of the foam sheets are influenced by the expansion ratio of the beads and the increase in the expansion ratio increased the foam resilience, decreased the hardness, and increased the tensile strength and elongation at break.

Adjusting cell structure of polypropylene composite foams by controlling the size and dispersed state of NaCl particles during CO2 batch foaming process

Polymer ◽  
2020 ◽  
Vol 194 ◽  
pp. 122406 ◽  
Author(s):  
Ziqi Liu ◽  
Jian Qiu ◽  
Zhiyuan Shi ◽  
Shaofeng Zhang ◽  
Haiping Xing ◽  
...  
Keyword(s):  
Cell Structure ◽  
Polypropylene Composite ◽  
Foaming Process ◽  
Composite Foams ◽  
Batch Foaming

Fabrication of poly (lactic acid) foams using supercritical nitrogen

2020 ◽  
Vol 39 (4) ◽  
pp. 172-182 ◽  
Author(s):  
Fatemeh Farhanmoghaddam ◽  
Azizeh Javadi
Keyword(s):  
Lactic Acid ◽  
Electrical Resistance ◽  
Cellular Structure ◽  
High Cell Density ◽  
Cell Structure ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
High Cell ◽  
Blowing Agent ◽  
Foaming Process

In this article, poly (lactic acid) (PLA) was foamed via batch foaming using supercritical nitrogen as a physical blowing agent by two methods, conventional foaming process (CFP) and low-temperature foaming process (LTFP). The fabrication processes, cell morphologies, thermal properties, crystallization behavior, and electrical resistance of resulted foams were studied to investigate the effect of foaming on these properties of PLA. It was found that the foams resulted from CFP method have micrometric cell sizes, while LTFP method led to nanometric cell structure and high cell density. Also scanning electron microscopy showed that the PLA foams have a heterogeneous cellular structure. The results showed that the foaming process increased the melting point and degree of crystallinity of PLA, which led to decrease in the electrical resistance of samples.

Experimental and numerical study of the polyurethane foaming process using high-pressure CO2

2020 ◽  
pp. 0021955X2097429
Author(s):  
Dongdong Hu ◽  
Chen Zhou ◽  
Tao Liu ◽  
Yichong Chen ◽  
Zhen Liu ◽  
...  
Keyword(s):  
Numerical Study ◽  
Cell Structure ◽  
Saturation Pressure ◽  
Gas Diffusion ◽  
Bubble Nucleation ◽  
Cell Diameter ◽  
Henry's Constant ◽  
Average Cell ◽  
Foaming Process ◽  
High Pressure Co2

A simulation of simultaneous bubble nucleation and growth was performed for polyurethane/CO2 physical foaming process. The single-factor and comprehensive effects of viscoelastic properties, Henry’s constant, CO2 diffusion coefficient and surface tension on the cell morphology were numerically analyzed. The results show that the cell density of PU foam ( N0) increases and its average cell diameter ( Dv) reduces with increased Henry’s constant and slower gas diffusion. Both N0 and Dv reduces with the curing degree ( α). In addition, the effects of α and foaming conditions on the cell structure were experimentally investigated. With an increase of α at foamable range, Dv decreases continuously and N0 increases first and then declines. With increasing saturation pressure and depressurization rate or decreasing temperature, N0 increases and Dv reduces. There is an intrinsic correlation between the simulated and experimental variables, and the results of the simulation and experiment are generally consistent.

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