Foam Extrusion with Physical Blowing Agents—Practical Approach

2014 ◽  
pp. 336-393
Keyword(s):  
Practical Approach ◽  
Blowing Agents ◽  
Foam Extrusion

scholarly journals Viscosity measurement of polypropylene loaded with blowing agents (propane and carbon dioxide) by a novel inline method

2019 ◽  
Vol 56 (1) ◽  
pp. 73-88
Author(s):  
Raphael Vincent ◽  
Martin Langlotz ◽  
Matthias Düngen
Keyword(s):  
Carbon Dioxide ◽  
Single Phase ◽  
Polymer Melt ◽  
Viscosity Measurement ◽  
Viscosity Reduction ◽  
Phase System ◽  
Melt Temperature ◽  
Blowing Agents ◽  
Foam Extrusion ◽  
Blowing Agent

Decreased viscosity due to the influence of blowing agent in thermoplastic polymer melts is a key issue for understanding the process of foam extrusion. In a process for direct foam extrusion, a novel approach for inline viscosity measurement of single-phase systems in single screw extruders is used to experimentally evaluate a viscosity decrease. Two blowing agents (propane and carbon dioxide) are tested for their effect on the viscosity of a polypropylene melt. While mass fractions of blowing agent below [Formula: see text] show little to no effect in regard to viscosity reduction compared to a pure polymer melt, a mass fraction of [Formula: see text] already results in significantly decreased viscosity values. While melt temperature influences the viscosity of the polymer melt, measurements show no significant additional effect in regard to a lowered viscosity of a single-phase system of polymer and fully dissolved blowing agent.

Foam Extrusion of Polystyrene Blown with HFC-134a

2002 ◽  
Vol 21 (5) ◽  
pp. 315-342 ◽  
Author(s):  
Richard Gendron ◽  
Michel Huneault ◽  
Jacques Tatibouët ◽  
Caroline Vachon
Keyword(s):  
Ozone Depletion ◽  
Chemical Structure ◽  
Industrial Processes ◽  
Polystyrene Foam ◽  
Screw Design ◽  
Blowing Agents ◽  
Foam Extrusion ◽  
Extrusion Processing ◽  
Hfc 134A ◽  
Hcfc 142B

There is much interest in developing industrial processes to manufacture extruded polystyrene foam that do not involve ozone depleting blowing agents. A popular alternate candidate is HFC-134a. It has a zero ozone depletion factor and is nearer in chemical structure to standard blowing agents (CFC-22 and HCFC-142b) than carbon dioxide. Although exhibiting main good features, HFC-134a is not used widely as a blowing agent as low foam density is not readily achieved and extruder operation is difficult. A review of past and on-going works on the use of HFC-134 will be addressed first. Then attention will be paid mainly on some processing aspects, with emphasis on the plasticization behavior of polystyrene (PS) by HFC-134a and the effect of screw design on dynamic dissolution of HFC-134a in PS during foam extrusion. Solubility efficiency during extrusion processing has been assessed for different screw configurations by an in-line ultrasonic technique. These results have also been correlated to off-line solubility and diffusivity properties.

Foam extrusion of PP-based wood plastic composites with chemical blowing agents and the Celuka technique

2016 ◽  
Vol 53 (6) ◽  
pp. 623-638 ◽  
Author(s):  
Christina Hoffmann ◽  
Marieluise Lang ◽  
Peter Heidemeyer ◽  
Martin Bastian ◽  
Katja Fischer ◽  
...  
Keyword(s):  
Fibre Length ◽  
Base Material ◽  
Wood Plastic Composites ◽  
Blowing Agents ◽  
Foam Extrusion ◽  
Density Reduction ◽  
Plastic Composites ◽  
Twin Screw ◽  
Chemical Blowing Agents ◽  
Wood Content

Wood plastic composites have gained relevance in recent years as an alternative to wood boards. However, because the cavities in wood fibres are compressed by high processing pressure during the extrusion of wood plastic composites, the product densities show a range of up to 1.5 g/cm3 depending on wood content and base material. Particularly in large-sized products, this may be disadvantageous for processors and end users. Foaming of the plastic matrix is a promising approach to reduce the density of wood plastic composites products. This article discusses the foam extrusion of PP-based wood plastic composites with chemical blowing agents in combination with the Celuka technique. Integral wood plastic composites foam with a rigid and plain outer layer was produced using a parallel, counter rotating twin screw extruder. The profiles obtained were analysed with respect to foam structure and mechanical properties. It was possible to achieve a density reduction of up to 0.7 g/cm3 in the foamed wood plastic composites profiles. Furthermore, we demonstrate that wood fibre length and type of chemical blowing agent have a strong effect on the resulting foam morphology.

scholarly journals A Study of the Solubility of Blowing Agents in Foam Extrusion Systems

Seikei-Kakou ◽  
1991 ◽  
Vol 3 (6) ◽  
pp. 425-430
Author(s):  
Tsuyoshi MIHAYASHI ◽  
Shigeru MOTANI ◽  
Takahiro HAYASHI ◽  
Hiroyuki YOSHIDA
Keyword(s):  
Blowing Agents ◽  
Foam Extrusion

Foam Extrusion

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Carbon Dioxide ◽  
Injection Molding ◽  
Cell Structure ◽  
Initial Pressure ◽  
Structural Foam ◽  
Molten Polymer ◽  
Blowing Agents ◽  
Foam Extrusion ◽  
Blowing Agent ◽  
Foam Injection Molding

There are two processes used in the production of thermoplastic foams, namely, foam extrusion and structural foam injection molding (Benning 1969; Frisch and Saunders 1973). Foam extrusion, in which either chemical or physical blowing agents are used, is the focus of this chapter. Investigations of foam extrusion have dealt with the type and choice of process equipment (Collins and Brown 1973; Knau and Collins 1974; Senn and Shenefiel 1971; Wacehter 1970), the effect of die design (Fehn 1967; Han and Ma 1983b), the effect of blowing agents on foaming characteristics (Burt 1978, 1979; Han and Ma 1983b; Hansen 1962; Ma and Han 1983), and relationships between the foam density, cell geometry, and mechanical properties (Croft 1964; Kanakkanatt 1973; Mehta and Colombo 1976; Meinecke and Clark 1973). Chemical blowing agents are generally low-molecular-weight organic compounds, which decompose at and above a critical temperature and thereby release a gas (or gases), for example, nitrogen, carbon dioxide, or carbon monoxide. Examples of physical blowing agents include nitrogen, carbon dioxide, fluorocarbons (e.g., trichlorofluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane), pentane, etc. They are introduced as a component of the polymer charge or under pressure into the molten polymer in the barrel of the extruder. It is extremely important to control the formation and growth of gas bubbles in order to produce foams of uniform quality (i.e., uniform cell structure). The fundamental questions one may ask in thermoplastic foam processing are: (1) What is the optimal concentration of blowing agent in order to have the minimum number of open cells and thus the best achievable mechanical property? (2) How many bubbles will be nucleated at the instant of nucleation? (3) What is the critical pressure at which bubbles nucleate in a molten polymer? (4) What are the processing–property relationships in foam extrusion and structural foam injection molding? Understandably, the answers to such questions depend, among many factors, on: (1) the solubility of the blowing agent in a molten polymer, (2) the diffusivity of the blowing agent in a molten polymer, (3) the concentration of the blowing agent in the mixture with a molten polymer, (4) the chemical structure of the polymers, (5) the initial pressure of the system, and (6) the equilibrium (or initial) temperature of the system.

Sign in / Sign up

Export Citation Format

Share Document