Study on the Foaming Behavior of PS-CO2 by Using Water or Ethanol as Co-Blowing Agent

2013 ◽  
Vol 748 ◽  
pp. 112-116 ◽  
Author(s):  
Yi Wei Luo ◽  
Chun Ling Xin ◽  
Jiao Sun ◽  
Bao Rui Yan ◽  
Ya Dong He
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Apparent Density ◽  
Expansion Ratio ◽  
Low Density ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Foaming Behavior ◽  
Low Solubility ◽  
Foam Production

Carbon dioxide (CO2) has been reported as an interesting substitute of banned ozone-depleting blowing agents, such as HCFC and HFC etc., for low-density polystyrene (PS) foam production, but it is difficult to industrialize due to its low solubility in PS matrix; therefore, high pressure is always needed in order to obtain the required gas concentrations for low density foam. Mixtures of blowing agents might be a practical way to make foam processing easy to control. In this paper, the foaming behaviors of PS-CO2 by using water or ethanol as co-blowing agent were investigated. The performances of foams obtained by PS-CO2, PS-CO2-water and PS-CO2-ethanol systems were tested respectively. It was found that cell size increased owing to the existence of co-blowing agent; in particular, the expansion ratio of PS foam obtained by CO2-ethanol was 1.3 times greater than that by CO2. At the same time, cell density as well as apparent density decreased with temperature increasing, while cell size showed the opposite. Cell size and apparent density, rather than cell density, decreased with pressure. These results were explained by the solution behavior of each of blowing agent.

scholarly journals Kinked Bisamides as Efficient Supramolecular Foam Cell Nucleating Agents for Low-Density Polystyrene Foams with Homogeneous Microcellular Morphology

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1094
Author(s):  
Bastian Klose ◽  
Daniel Kremer ◽  
Merve Aksit ◽  
Kasper P. van der Zwan ◽  
Klaus Kreger ◽  
...  
Keyword(s):  
Cell Size ◽  
Self Assembly ◽  
Large Scale ◽  
Elevated Temperatures ◽  
Foam Cell ◽  
Cell Structure ◽  
Expansion Ratio ◽  
Low Density ◽  
Nucleating Agents ◽  
Foam Density

Polystyrene foams have become more and more important owing to their lightweight potential and their insulation properties. Progress in this field is expected to be realized by foams featuring a microcellular morphology. However, large-scale processing of low-density foams with a closed-cell structure and volume expansion ratio of larger than 10, exhibiting a homogenous morphology with a mean cell size of approximately 10 µm, remains challenging. Here, we report on a series of 4,4′-diphenylmethane substituted bisamides, which we refer to as kinked bisamides, acting as efficient supramolecular foam cell nucleating agents for polystyrene. Self-assembly experiments from solution showed that these bisamides form supramolecular fibrillary or ribbon-like nanoobjects. These kinked bisamides can be dissolved at elevated temperatures in a large concentration range, forming dispersed nano-objects upon cooling. Batch foaming experiments using 1.0 wt.% of a selected kinked bisamide revealed that the mean cell size can be as low as 3.5 µm. To demonstrate the applicability of kinked bisamides in a high-throughput continuous foam process, we performed foam extrusion. Using 0.5 wt.% of a kinked bisamide yielded polymer foams with a foam density of 71 kg/m3 and a homogeneous microcellular morphology with cell sizes of ≈10 µm, which is two orders of magnitude lower compared to the neat polystyrene reference foam with a comparable foam density.

Expandable polystyrene without any embedded blowing agent

2020 ◽  
pp. 0021955X2094497
Author(s):  
Habib Haji Avdi ◽  
Morteza Nasiri ◽  
Mohammad Javad Tehrani ◽  
Maryam Alizadeh Aghdam ◽  
Farhang Abbasi
Keyword(s):  
Suspension Polymerization ◽  
Expansion Ratio ◽  
Scanning Calorimetry ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Rate Of Polymerization ◽  
Polystyrene Matrix ◽  
Expandable Polystyrene ◽  
Before And After

In this research, in-situ suspension polymerization of styrene in the presence of graphene, without any blowing agent, was investigated. Steam used in the expansion process of graphene-filled expandable polystyrene (GEPS). The dispersed graphene nano-sheets in the polystyrene matrix may absorb water in high temperatures, which evaporates by lowering the pressure and expansion precedes. The effects of graphene type and loading and steam temperature on the expansion ratio evaluated. Scanning electron microscopy (SEM) used to reveal the cross-section morphologies before and after expansion. The effect of graphene on the polymerization kinetics evaluated by differential scanning calorimetry (DSC). The results showed that by increasing the graphene loading, the rate of polymerization decreased, and the expansion ratio increased. The highest expansion ratio of about 4.8 was for particles containing 0.4% of graphene. Therefore, it was shown that by using graphene as a dispersed phase, polystyrene particles expanded without any organic blowing agents. Here, the idea of expandable polymers without any embedded blowing agent is introduced, which eliminates the release of volatile organic compounds and makes the process environmentally friendly.

Effect of Foaming Temperature Control on Cell Size and Cell Density of Microcellular Plastics

2005 ◽  
Vol 24 (2) ◽  
pp. 91-102 ◽  
Author(s):  
Hidetaka Kawashima ◽  
Minoru Shimbo
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Average Cell Size ◽  
Average Cell ◽  
Blowing Agent ◽  
Microcellular Plastics ◽  
Temperature Method ◽  
Foamed Plastics ◽  
Maximum Cell ◽  
Foaming Temperature

In this study, noticing foaming temperature as a factor, which induces thermodynamic instability for cell nucleation of Microcellular plastics, the effect of control method of foaming temperature on cell size and cell density - that is number per unit volume of foamed plastics - were investigated. Generally, foaming by using batch process is carried out as follows. First, blowing agent is soaked into plastics until saturation under high pressure and soaking temperature. After plastics were saturated with blowing agent, pressure is released rapidly and then temperature is raised to foaming temperature and cells are nucleated and grown. Finally, rapid cooling controls cell growth. In this case, two methods can be considered for the control of foaming temperature. One is the elevated temperature method in which temperature is raised to foaming temperature and cells are grown after decompression in the foaming process. The other is the constant temperature method in which the temperature is already kept at foaming temperature before decompression. That is, it is the method of performing soaking and foaming at the same temperature. Polymethylmethacrylate (PMMA) resins were foamed under foaming conditions which the same foaming magnification is produced by both methods and cell size and cell density of foamed PMMA were investigated. As results, in case of production of the foamed plastics having the same foam magnification, it turned out that cell density of foamed plastics becomes large and average cell size becomes small but the maximum cell size becomes large by the elevated temperature method. On the other hand, although the maximum cell size becomes small, average cell size becomes large by the constant temperature method.

Effect of Beeswax on Batch Foaming of PLA

2013 ◽  
Vol 779-780 ◽  
pp. 327-331
Author(s):  
Kun Chang Lin ◽  
Chia Hsun Chen ◽  
Shang Min Chen ◽  
Sian Nan Sie
Keyword(s):  
Solid State ◽  
Deformation Behavior ◽  
Tensile Strain ◽  
Expansion Ratio ◽  
Ductile Deformation ◽  
Low Density ◽  
Brittle Deformation ◽  
Foaming Process ◽  
Foaming Behavior ◽  
Ductile Behavior

This paper presents the foaming behavior of PLA-CO2 and PLA/beeswax-CO2 systems for solid state foaming process with particular goal of producing low density foams. The low density PLA foams can be achieved under 2 MPa sub-critical CO2 condition due to CO2-induced crystalline. When 10wt% beeswax was added to PLA matrix, the tensile strain at break increases from 7.9% to 22.2% and crystallinity remain unchanged. The inherent brittle deformation behavior of the PLA was transformed into relatively ductile behavior after blending 10wt% beeswax. The expansion ratio of neat PLA and its blends with 10wt% beeswax increase from 1.08 to 19.4. The ductile deformation behavior of PLA is an important factor for solid-state PLA foam.

Multi-Stage Recycling Induced Morphological Transformations in Solid-State Microcellular Foaming of Polystyrene

2018 ◽  
Vol 37 (3) ◽  
pp. 121-149 ◽  
Author(s):  
Indrajeet Singh ◽  
Abhishek Gandhi ◽  
Manoranjan Biswal ◽  
Smita Mohanty ◽  
S. K. Nayak
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Saturation Pressure ◽  
Expansion Ratio ◽  
General Purpose ◽  
Microcellular Foam ◽  
Cell Size Distribution ◽  
Microcellular Foaming ◽  
Multi Stage ◽  
Morphological Transformations

In this article, the general-purpose polystyrene was reprocessed four times. The effect of repeated reprocessing of polystyrene on its polymeric properties and on its microcellular, foaming behaviour were investigated. It was observed that reprocessing leads to break of long polymeric chains into short chains, which resulted increment in PDI and MFI. Molecular weight and Glass transition temperature were found to decrease with increasing recycling stages. Reprocessing resulted abruptly decrement in viscosity of neat polystyrene. Effect of reprocessing on foaming behaviour was analysed properly in this report and it was found that reprocessing resulted in improvement in cell sizes and their distribution. A positive effect on expansion ratio was also observed during foaming of reprocessed specimens. Cell density was found to decrease with increasing recycling stages. The effect of saturation pressure and foaming temperature on microcellular foam morphology along with recycling were investigated. Effect of foaming time on cell size, cell size distribution, cell density, expansion ratio and cell wall thickness was investigated.

Morphological, thermo-mechanical, and thermal conductivity properties of halloysite nanotube-filled polypropylene nanocomposite foam

2016 ◽  
Vol 54 (2) ◽  
pp. 217-233 ◽  
Author(s):  
Renan Demori ◽  
Eveline Bischoff ◽  
Ana P de Azeredo ◽  
Susana A Liberman ◽  
Joao Maia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Size ◽  
Cell Density ◽  
Void Fraction ◽  
Cell Structure ◽  
Cell Size Distribution ◽  
Halloysite Nanotube ◽  
Dynamic Mechanical ◽  
Foaming Behavior ◽  
Homogeneous Cell

Studies about polypropylene nanocomposite foams are receiving attention because nanoparticles can change physical and mechanical properties, as well as improve foaming behavior in terms of homogeneous cell structure, cell density, and void fraction. In this research, the foaming behavior of polypropylene, polypropylene/long-chain branched polypropylene (LCBPP) 100/20 blend, and polypropylene/LCBPP/halloysite nanocomposites with 0.5 and 3 parts per hundred of resin (phr) is studied. The LCBPP was used to improve the rheological properties of polypropylene/LCBPP blend, namely the degree of strain-hardening. Transmission electron microscopy observation indicated that halloysite nanotube particles are well distributed in the matrix by aggregates. Subsequent foaming experiments were conducted using chemical blowing agent in injection-molding processing. Polypropylene foam exhibited high cell density and cell size as well as a collapsing effect, whereas the polypropylene/LCBPP blend showed a reduction of the void fraction and cell density compared to expanded polypropylene. Also, the blend showed reduction of the collapsing effect and increase of homogeneous cell size distribution. The introduction of a small amount of halloysite nanotube in the polypropylene/LCBPP blend improved the foaming behavior of the polypropylene, with a uniform cell structure distribution in the resultant foams. In addition, the cell density of the composite sample was higher than the polypropylene/LCBPP sample, having increased 82% and 136% for 0.5 and 3 phr of loaded halloysite nanotube, respectively. Furthermore, the presence of halloysite nanotube increased crystallization temperature (Tc) and slightly increased dynamic-mechanical properties measured by dynamic-mechanical thermal analysis. By increasing halloysite nanotube content to 3 phr, the insulating effect increased by 13% compared to polypropylene/LCBPP blend. For comparative purposes, the effect on foaming behavior of polypropylene/LCBPP was also investigated using talc microparticles.

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.

The Effect of Compatibilization on the Properties and Foaming Behavior of Poly(ethylene terephthalate)/Poly(ethylene-octene) Blends

2017 ◽  
Vol 36 (6) ◽  
pp. 313-332 ◽  
Author(s):  
Wenbo Wang ◽  
Kesong Yu ◽  
Hongfu Zhou ◽  
Xiangdong Wang ◽  
Jianguo Mi
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Ethylene Terephthalate ◽  
Complex Viscosity ◽  
Elongation At Break ◽  
Brittle Ductile Transition ◽  
Poly Ethylene Terephthalate ◽  
Blending Method ◽  
Foaming Behavior ◽  
Poly Ethylene

The methodology for improving the properties and foaming behavior of poly (ethylene terephthalate) (PET)/poly(ethylene-octene) (POE) blends through compatibilization was proposed. In this paper, PET/POE blends were prepared through a melt blending method, POE was employed as elastomer toughener, maleic anhydride grafted POE (mPOE) was selected as compatibilizer, and pyromellitic dianhydride (PMDA) was used as chain extender. The content of mPOE was changeable to study the effect of compatibility on crystallization behavior, toughness, dispersion morphology, and rheological behavior of PET/ POE blends. The results demonstrated that the crystallization peak of PET/POE blends shifted towards high temperatures from 196.97°C to 201.24°C with the content of mPOE increasing. The brittle-ductile transition for PET/POE blends occurred at the mPOE content in the range of 4–5 phr. The particle size of POE dispersed phase decline firstly and then was almost unchanged with an increasing content of mPOE. The storage modulus and complex viscosity of compatibilized PET/POE blends were obviously higher than that of uncompatibilized PET/POE blends. Then PET/POE blends were foamed using supercritical CO2 as physical blowing agent. The results showed that the cell size, cell density, and tensile properties of the PET/POE blending foams were affected by the content of mPOE strongly. With the content of mPOE, the cell size decreased and then kept stable as well as the cell density the trend of cell size increased then remained unchanged. In addition, the elongation at break of PET/POE blending foams was higher than that of the uncompatibilized PET/POE blending foam. PET/POE blending foams with fine cell morphology and good ductility could be achieved with a proper content of compatibilizer in the blends.

Physico-mechanical properties and cell microstructure of cross-linked PVC/organoclay nanocomposite foams prepared at various processing conditions

2020 ◽  
pp. 089270572097869
Author(s):  
Pezhman Rezaei ◽  
Mostafa Rezaei ◽  
Saeid Talebi ◽  
Amin Babaie
Keyword(s):  
Mechanical Properties ◽  
Size Distribution ◽  
Cell Size ◽  
Cell Density ◽  
Expansion Ratio ◽  
Molding Pressure ◽  
Cell Size Distribution ◽  
Gel Content ◽  
Nanocomposite Foams ◽  
Cloisite 30B

Cross-linked polyvinyl chloride (C-PVC) foams and their nanocomposite foams, containing Cloisite 30B nanoclays were prepared. The effects of compression molding pressure and time on the morphology and mechanical properties of different foams were studied. Increment of molding pressure led to higher apparent density, gel content, cell density, and expansion ratio, and wider cell size distribution, which improved the mechanical properties of the foams. Additionally, with the increasing of molding time, lower cell density and final expansion ratio, narrower cell size distribution, and higher gel content and mechanical properties could be obtained. Moreover, incorporation of Cloisite 30B nanoclay in a PVC matrix not only improved cellular microstructure and mechanical properties but also reduced water uptake ratios of nanocomposite foams.

scholarly journals Properties of polyurethane foam with fourth-generation blowing agent

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 763-769
Author(s):  
Vladimir Yakushin ◽  
Ugis Cabulis ◽  
Velta Fridrihsone ◽  
Sergey Kravchenko ◽  
Romass Pauliks
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Cellular Structure ◽  
Fourth Generation ◽  
Low Density ◽  
Technological Parameters ◽  
Blowing Agent ◽  
Foam Properties ◽  
Rise Direction ◽  
Foam Production

Abstract Climate change makes it imperative to use materials with minimum global warming potential. The fourth-generation blowing agent HCFO-1233zd-E is one of them. The use of HCFO allows the production of polyurethane foam with low thermal conductivity. Thermal conductivity, like other foam properties, depends not only on the density but also on the cellular structure of the foam. The cellular structure, in turn, depends on the technological parameters of foam production. A comparison of pouring and spray foams of the same low density has shown that the cellular structure of spray foam consists of cells with much less sizes than pouring foam. Due to the small size of cells, spray foam has a lower radiative constituent in the foam conductivity and, as a result, a lower overall thermal conductivity than pouring foam. The water absorption of spray foam, due to the fine cellular structure, also is lower than that of pouring foam. Pouring foam with bigger cells has higher compressive strength and modulus of elasticity in the foam rise direction. On the contrary, spray foam with a fine cellular structure has higher strength and modulus in the perpendicular direction. The effect of foam aging on thermal conductivity was also studied.

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