The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation

K. Major - Gabryś

English

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591METALURGIJA 54 (2015) 3, 591-593K. MAJOR - GABRYŚBIODEGRADABLE MATERIALS AS FOUNDRY MOULDING SANDS BINDERSReceived – Prispjelo: 2014-09-17Accepted – Prihvaćeno: 2015-01-10Review Paper – Pregledni radISSN 0543-5846METABK 54(3) 591-593 (2015)UDC – UDK 621.746:621.74.04:678.7=111K. Major - Gabryś, AGH University of Science and Technology, Faculty of Foundry Engineering, Krakow, PolandThe aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials  selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation.Key Words: foundry practice, moulding sand, biodegradable polymer, toxicity, reclamationINTRODUCTIONFoundry is an area of science which will never have just one technology of preparing moulding sands and only one technology of preparing core sands. The variety of materials of which castings are made (types of alloys and their casting temperature) will always make foundry-men face the requirements for obtaining moulds and cores with high technological properties. Moreover, ac-cording to tendencies observed in recent years, foundry mould and core manufacturing technologies must also meet high environmental protection requirements. The group of binders which are predominant in the produc-tion of foundry moulds and cores comprises synthetic (petrochemical) resins used in processes such as loose self-hardening mo ulding sands (no-bake technology), cold-box technologies and hot-box technologies. Phenol, urea and furfuryl resins are especially used. Increased en-vironmental protection requirements necessitate changes in foundry practices. Many domestic and foreign scien-tific centers have been trying to develop new non-toxic foundry moulding sand binding systems [1 - 3]. The cur-rent direction in modern scientific research is to gradual-ly replace binding materials produced from petrochemi-cal stocks with biomaterials originating from renewable resources. This direction is consistent with the concept of sustainable development which is one of the priorities of the European Community policy [4].BIODEGRADABLE POLYMERS IN FOUNDRY MOULDING SANDSAccording to ASTM standard D-5488-94d, “biode-gradable” means “capable of undergoing decomposi-tion into carbon dioxide, methane, water, inorganic compounds or biomass”, where the predominant mech-anism is the enzymatic action of microorganisms. The mechanism can be measured by standard tests, over a specific period of time, with available disposal condi-tions. There are different media (liquid, inert or com-post medium) to analyze biodegradability [4].During the ’90s, General Motors Corporation devel-oped a new binding system based on the protein compo-sition called GMBOND [5]. K. Rusin’s scientific group [6] tested the possibility of using biogenic binders based on proteins derived as by-products of pharmaceutical industry. B. Grabowska [7 - 8] proposed the use of aqueous biodegradable polymeric compositions con-sisting of acrylic derivatives and modified natural poly-mers (BioCo binders) as moulding sand binders in foundry.RESEARCH AND DISCUSSIONBased on literature [9], the author assumes that a possibility exists to replace part of organic petrochemi-cal binder commonly used in foundry practice with or-ganic biodegradable material. The replacement can im-prove the binder quality. The first step of the author’s research was to conduct tests using biodegradable mate-rials as moulding sand binders. The search for produc-ers of biodegradable polymers resulted in selecting the following materials as binders: poly(lactic acid), poly(lactic-co-glycolic acid), polycaprolactone, poly-hydroxybutyrate and cellulose acetate.According to literature [9], polycaprolactone is of-ten used as an additive in resins to improve their pro-cessing characteristics and their end use properties (such as impact resistance). Since it is compatible with a range of other materials, polycaprolactone can be 592K. MAJOR - GABRYŚ: BIODEGRADABLE MATERIALS AS FOUNDRY MOULDING SANDS BINDERS METALURGIJA 54 (2015) 3, 591-593mixed with starch to lower its cost and increase biodeg-radability or it can be added as a polymeric plasticizer to poly(vinyl chloride) (PVC).In previous studies, the author [1] used selected bio-degradable materials as binders for moulding sands. The research proved that moulding sands combined with biodegradable binders showed satisfactory strength properties [1].To measure the toxicity, moulding sand was used, composed of 100 parts by weight of quartz sand and 2 parts by weight of biodegradable poly(lactic acid). In comparison testing, a typical self-hardening moulding sand with furfuryl resin was used, composed of 100 parts by weight of quartz sand and 1,1 part by weight of phe-nol-furfuryl resin hardened with 0,55 part by weight of aqueous solution of paratoluenosulphonic acid (PTS) [1].The hardening of moulding sand bound with poly(lactic acid) was followed by solvent evaporation. The research was conducted using a multifunction de-vice designed to examine the surface properties of liq-uid alloys. The construction of the device allowed for permanent registration of residual gases content using the quadruple mass analyzer Prisma QMS-200 manu-factured by Pfeiffer Co. The research was conducted under high vacuum conditions. Toxicity tests of the hardened moulding sands showed that fewer harmful substances developed during pouring of moulding sand bound with poly(lactic acid) (Figures 1 - 2) [1].The problem is the toxicity of organic solvents used to dissolute biopolyesters and the toxicity of moulding sand production process. It seems reasonable to investi-gate whether there is a possibility of inserting biode-gradable materials into the sand after their earlier dis-solution in an organic water-soluble solvent and then inserting the water (as a second solvent) into the solu-tion. In that case the moulding sand would be made of sand grains and biodegradable binder particles in an aqueous suspension.One of the points of the paper is checking the pos-sibility of increasing the biodegradation rate of binding materials used. However, it must be clearly stated that biodegradation of biodegradable materials used in foundry practice will not replace reclamation processes that are necessary to recover sand grains. The author’s own research proved that moulding sands with biode-gradable materials selected as binders are not only less toxic [1] but are also better suited to mechanical recla-mation than moulding sands with phenol-furfuryl resin that were used [10].The testing involved using moulding sands with bio-degradable binders with the quantity of 2 parts by weight and a typical self-hardening moulding sand with phenol-furfuryl resin with the same composition as in toxicity tests. All the tested moulding sand portions consisted of moulding sands heated at temperatures of 200, 600 and 800 oC and of unheated moulding sand [10].The testing schedule of the ability to reclaim the moulding sands included the following: crushing the material before secondary reclamation; the secondary reclamation treatment within 10 and 20 minutes of rec-lamation; the final classification (pneumatic) of the ma-terial obtained in reclamation process. The moulding sands and their leftovers were analyzed to define the de-gree of releasing sand grains from binder leftovers in moulding sands. The following were analyzed: ignition loss, determining the degree of releasing sand grains from binder leftovers in moulding sands (WSR), defining the dusts content, value of pH, analyzing the surface morphology and sieve analysis. All the obtained results were showed in the previous paper by the author [10], which proved that moulding sands with biodegradable binders had high capability of reclamation with their pa-rameters much exceeding analogical parameters of typi-cal moulding sand bound using phenol-furfuryl resin.It can be concluded that the partial replacement of resin with a biodegradable material will increase the ability to reclaim the moulding sands with new binders.CONCLUSIONSAnalysis of literature data and the author’s own re-search yield the following conclusions:• It is possible to develop theoretical foundations and procedures for the production of synthetic resins combined with biodegradable materials as binders for foundry moulding and core sands.• The use of synthetic resins combined with biode-gradable materials as binders for foundry moulding and core sands may reduce their toxicity.Figure 2  Analysis of gases generated during heating of moulding sand bound with phenol-furfuryl resin [1]Figure 1  Analysis of gases generated during heating of moulding sand with poly(lactic acid) [1]593K. MAJOR - GABRYŚ: BIODEGRADABLE MATERIALS AS FOUNDRY MOULDING SANDS BINDERSMETALURGIJA 54 (2015) 3, 591-593• The use of synthetic resins combined with biode-gradable materials as binders for foundry moulding and core sands may increase their capability of rec-lamation.• The use of synthetic resins combined with biode-gradable materials as binders for foundry moulding and core sands may result in partial biodegradation of binder leftovers of mechanical reclamation.AcknowledgementsScientific paper financed by AGH Research Project No 11.11.170.318 - 3REFERENCES[1]  St. M. Dobosz, P. Jelinek, K. Major - Gabryś, Develop-ment Tendencies of Moulding and Core Sands, China Foundry, 8 (2011) 4, 438-446.[2]  A. Wolff, T. Steinhaeuser, AWB - an Environment-Friend-ly Core Production Technology, Giesserei, 91 (2004) 6, 80-84.[3]  M. Stachowicz, K. Granat, Possibilities of Reclamation Microwave-Hardened Molding Sands with Water Glass, Ar-chives of Metallurgy and Materials, 59 (2014) 2, 757-760.[4]  L. Avérous, E. Pollet, Environmental Silicate Nano-Bio-composites, Springer, London, 2012, pp. 13-40.[5]  J. Eastman, Protein-Based Binder Update: Performance Put to the Test, Modern Casting, October (2000), 32-34.[6]  D. Kramářová, J. Brandštetr, K. Rusín, P. Henzlová, Bio-genní polymerní materiály jako pojiva slévárenských fo-rem a jader, Slévárenství, 60 (2003) 2-3, 71-73.[7]  B. Grabowska, Nowe spoiwa polimerowe w postaci wodnych kompozycji z udziałem poli(kwasu akrylowego) lub jego soli i modyfikowanego biopolimeru do zastoso-wania w odlewnictwie, Wydawnictwo Naukowe Akapit, Krakow, 2013, pp. 87-107.[8]  B. Grabowska, M. Holtzer, R. Dańko, M. Górny, A. Bo-browski, E. Olejnik, New BioCo Binders Containing Bio-polymers for Foundry Industry, Metalurgija, 52 (2013) 1, 47-50.[9]  E. - J. Choi, J. - K. Park, Study on Biodegradability of PCL/SAN Blend Using Composting Method, Polymer De-gradation and Stability, 52 (1996) 3, 321-326.[10]  K. Major - Gabryś, St. M. Dobosz, R. Dańko, J. Jakubski, The Estimation of Ability to Reclamation of Moulding Sands with Biopolymer Binders, Archives of Foundry En-gineering, 11 (2011) 2, 79-84.Note:  Translator responsible for the translation into English is professional certified corporation: LingPerfect Translations, Inc., New York, USA

Biodegradable materials as foundry moulding sands binders

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