Blowing Agents - April 2009

This month we're focusing on the topic of Blowing Agents

Additives impact polymers in different ways. Some additives (e.g. some antimicrobials) have inherent properties which they bring to the finished polymer. Other additives, like blowing agents, take effect during the processing of the polymer and bring about structural changes so that the polymer itself has the properties required. As such, the blowing agents are closely linked with the processing stage but once the polymer has been formed their role is virtually redundant. The blowing agent used (and therefore the gas within the foam) only really need consideration again when it is time to recycle or dispose of the foam item they have helped to make.

Blowing agents are used to make a broad selection of foams which have wide-ranging functions. Environmental considerations are always paramount and the development of new, more environmentally friendly options is always ongoing.

Abstracts

Please see below a selection of abstracts highlighted in the April Newsletter. These are records which relate to Blowing Agents that have been recently added to the Polymer Library.

Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.

1036651 - HFCS & BEYOND - ENERGY EFFICIENT AND COST EFFECTIVE HCFC REPLACEMENT TECHNOLOGIES FOR RIGID POLYURETHANE FOAMS
In response to the Montreal Protocol on Substances that Deplete the Ozone Layer, the production of foams containing HCFC-141b has been phased out in several countries, including the US, Japan and the EU. The use of this blowing agent will be phased out over the next several years in the rest of the world. Honeywell has developed and commercialised a zero ozone depletion potential blowing agent, Enovate blowing agent (HFC-245fa, 1,1,1,3,3-pentafluoropropane) as a non-flammable, liquid replacement for HCFC-141b in PU and polyisocyanurate foams. Many rigid foam applications that had traditionally used HCFC-141b as the blowing agent, including appliances, spray foam, discontinuous and continuous panels, and others, have converted to Enovate during this phase-out, and it is anticipated that a similar conversion to Enovate will occur in other countries around the world as they complete their transitions. This paper compares the properties of foams prepared using HCFC-141b and other blowing agents in several major foam applications, including appliances, spray foam and pour in place panels. The paper also discusses some of the design considerations necessary to convert processing equipment from HCFC-141b to Enovate. 9 refs.
Polyurethanes Today, 1, No.7, Dec.2008, p.30/37
Ling J Y K

1036312 - FOAMS SEEK SUSTAINABILITY. MATERIAL AND PROCESS DEVELOPERS SHOOT FOR 'GREENER' POLYMERIC FOAMS
Foamed plastics are critical components in many safety, insulation and weight-saving applications, a fact which contrasts with the often negative public image of foam packaging. A report is presented on developments in foaming, reported at the SPE Foams 2008 conference, which are driving new applications while confronting the environmental issues of high-volume foam production through more sustainable materials and processes. The use of foamed bioplastics is discussed, together with new blowing agent technologies and recycling-friendly strategies.
Plastics Engineering, 65, No.1, Jan.2009, p.6/8, ISSN: 0091-9578
Tolinski M

1036307 - SUSTAINABLE DISPOSAL OPTIONS PRESENT A FURTHER LIFECYCLE BONUS FOR POLYISOCYANURATE COMPOSITE PANEL SYSTEMS
Lifecycle parameters of polyisocyanurate, as used in thermal insulation composite panels, and a sustainable practice for end-of-life are described. Re-use of the panels is discussed. Recycling and disposal are considered, with reference to the problem of dealing with blowing agents, to costs and to benefits to the climate. The potential for development of a technically feasible and economically viable means of dealing with end-of-life issues and, in particular, the legacy of earlier ozone-depleting substance use is considered.
PU Magazine, 5, No.6, Dec.2008, p.373-377
Harris M

1036029 - EFFECTS OF SILICONE SURFACTANT ON THE CELL SIZE AND THERMAL CONDUCTIVITY OF RIGID POLYURETHANE FOAMS BY ENVIRONMENTALLY FRIENDLY BLOWING AGENTS
Rigid PU foams were prepared using environmentally friendly blowing agents, such as a cyclopentane/distilled water mixture and distilled water, and several silicone surfactants with varying silicone/polyether ratios. The effect of the surfactants on the cell size and thermal conductivity of the foams was investigated and the relationship between cell size, thermal conductivity and silicone/polyether ratio of the surfactants examined. Foam morphology was determined by field emission scanning electron microscopy. The results obtained revealed that rigid foams with low thermal conductivity could be obtained using a silicone surfactant containing a higher silicone/polyether ratio and an optimum amount of surfactant. 34 refs.
Macromolecular Research, 17, No.1, Jan.2009, p.44-50, ISSN: 1598-5032
Mi Sun Han; Seok Jin Choi; Ji Mun Kim; Youn Hee Kim; Woo Nyon Kim; Heon Sang Lee; Joon Yong Sung

1035749 - THEORETICAL AND EXPERIMENTAL STUDY OF FOAMING PROCESS WITH CHAIN EXTENDED RECYCLED PET
The fabrication of foamed sheets of recycled poly(ethylene terephthalate) (PET) via reactive processing of scrap PET with pyromellitic dianhydride as chain extender and subsequent foaming of the chain extended PET by extrusion using a chemical blowing agent was investigated, and the products were characterised by SEM, density, tensile and flexural properties. The development of a non-isothermal model to predict foam morphology, taking into account mass transfer phenomena and the effects of viscous forces is described, and the results of simulations are discussed in comparison with experimental data for different processing conditions. 26 refs.
Express Polymer Letters, 3, No.2, 2009, p.84-96, ISSN: 1788-618X, DOI: 10.3144/expresspolymlett.2009.12
Coccorullo I; Di Maio L; Montesano S; Incarnato L

1035077 - GENERATION OF LOW-DENSITY HIGH-PERFORMANCE POLY(ARYLENE ETHER SULFONE) FOAMS USING A BENIGN PROCESSING TECHNIQUE (downloadable pdf available)
In this study, a benign process was used to successfully produce low density foam from poly(arylene ether sulphone) (PAES). Both carbon dioxide (CO2) and water as well as nitrogen and water were used as physical blowing agents in a one-step batch process. A large amount of blowing agents (up to 7.5%) was able to diffuse into the PAES resin in a 2-h saturation time. Utilizing water and CO2 as the blowing agents yielded foam with better properties than nitrogen and water because both the water and CO2 are plasticisers for the PAES resin. PAES foam produced from CO2 and water had a large reduction in foam density (about 80%) and a cell size of about 50 micro m, while maintaining a primarily closed cell structure. The small cell size and closed cell structure enhanced the mechanical properties of the foam when compared with the PAES foam produced from nitrogen and water. The tensile, compressive, and notched izod impact properties of the PAES foams were examined, and the compressive properties were compared to commercially available structural foams. With reduced compression strength of 39 MPa and reduced compression modulus of 913 MPa, the PAES foam is comparable to polyetherimide and poly(vinylchloride) structural foams. 36 refs.
Polymer Engineering and Science, 49, No.1, 2009, p.44-51, ISSN: 0032-3888, DOI: 10.1002/pen.21214
VanHouten D J; Baird D G

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