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From page 7... ... 2-1 SECTION 2 SUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM The initial phase of the research focused on identifying alternatives for four major deicer components based on their contributions to BOD and toxicity: • FPDs: 26 candidates • Thickeners: 5 candidates • Surfactants: 19 candidates • Corrosion Inhibitors: 17 candidates Also identified were two candidate anti-caking additives for use in sodium formate runway deicers and one candidate antifoam for use in deicing formulations. A combination of molecular modeling, database searches, and literature searches were used to identify candidates for each of these component classes. Read the entire page →
From page 8... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-2 • FPDs contain several oxygen atoms. This increases the hydrogen bonding and polar interactions with water, in addition to lowering the chemical's BOD. Read the entire page →
From page 9... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-3 Each of these 160 candidate chemical formulas was used to search for commercially available chemicals using the National Institute of Standards and Technology Chemistry WebBook (5) Read the entire page →
From page 10... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-4 Figure 2-1. Flash points for mixtures of alcohol and water. Read the entire page →
From page 11... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-5 TABLE 2-2. ThOD of some current FPDs. Read the entire page →
From page 12... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-6 by the horizontal dashed line, denotes the solid phase. The regions below the curves but above the eutectic point indicate two phase regions -- a mixture of solid and liquid phases. Read the entire page →
From page 13... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-7 Figure 2-4. Variation of eutectic point with variation in enthalpy of fusion (∆Hm is given in units of kJ/mol) Read the entire page →
From page 14... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-8 fluid into the two-phase, solid-liquid region, which could result in formation of residuals on the aircraft surface. From this analysis, an upper limit of 50°C was set on the freezing point of candidate FPDs. Read the entire page →
From page 15... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-9 TABLE 2-4. 96-hour P Read the entire page →
From page 16... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-10 Because this LC50 is greater than the toxicity constraint, 1,2-propylene glycol was retained for further consideration. Unfortunately, aquatic toxicity data were found for only 12 of the remaining 27 candidates. Read the entire page →
From page 17... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-11 TABLE 2-5. Candidate FPDs recommended for further evaluation. Read the entire page →
From page 18... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-12 containing sulfur were not included because of corrosion concerns. Table 2-6 shows how the molecular structure of some of the FPDs listed above can be represented by these groups. Read the entire page →
From page 19... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-13 Flash Point Paragraph 3.2.1 of AMS specification 1435A states that runway deicing fluids must have a flash point not lower than 100°C. Paragraph 3.2.2 of AMS specification 1431B states that runway deicing solids must have a flash point not lower than 93°C. Read the entire page →
From page 20... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-14 TABLE 2-8. Freezing points of aqueous deicing chemical solutions. Read the entire page →
From page 21... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-15 Melting, Penetration, and Undercutting Unlike aircraft deicing chemicals, runway deicers do not need to completely melt accumulated ice and snow. National Research Council publication SHRP-H-332 (15) Read the entire page →
From page 22... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-16 modified. The approximate freezing point depression caused by adding any chemical to water is given by Equation 2-3. Read the entire page →
From page 23... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-17 this limit was established for screening purposes, the goal is to develop new products with toxicities as low as possible.) Aquatic toxicity data were found for 19 of the remaining 47 candidates. Read the entire page →
From page 24... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-18 satisfy the selection constraints for new PDM formulations with improved environmental characteristics. Several of these candidates are used in current runway deicing products. Read the entire page →
From page 25... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-19 Thickener Candidates Figure 2-8 shows the rheological behavior (flow of fluids under strain) of a typical anti-icing fluid. Read the entire page →
From page 26... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-20 1. Polysaccharides: These agents are long-chain polymers comprising repeat sugar units. Read the entire page →
From page 27... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-21 5. Locust Bean Gum: obtained from the seed of the carob tree, which grows in several Mediterranean countries. Read the entire page →
From page 28... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-22 thickener with acceptable properties. Experimental evaluation of hydroxyethylcellulose may help determine if ionic nature influences aquatic toxicity. Read the entire page →
From page 29... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-23 by the mixture's high surface energy -- creating a new surface requires considerable energy, so the liquid attempts to minimize its surface area by forming a spherical drop. Surfactants are added to aircraft deicing and anti-icing fluids to reduce their surface energy. Read the entire page →
From page 30... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-24 tendency to create stable foams. Surfactants with low HLB values are very lipophilic and promote water-in-oil emulsions. Read the entire page →
From page 31... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-25 TABLE 2-12. Non-ionic surfactant categories. Read the entire page →
From page 32... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-26 E lists detailed information on these surfactant candidates. Samples of Pluronic L44 NF could not be obtained and so it was dropped from further consideration. Read the entire page →
From page 33... ... SECTION 2 -- 1BSUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM 2-27 Corrosion Inhibitor Candidates The corrosion of a metal requires oxygen, a conductive solution, and surface areas with differing chemical potential. Because most deicing and anti-icing chemicals contain salts or are mixed with water that contains salts, corrosion of steel and aluminum can readily occur. Read the entire page →
From page 34... ... ALTERNATIVE AIRCRAFT ANTI-ICING FORMULATIONS 2-28 Two additives that have been used or have been proposed for preventing the caking of formate particles are: • Potassium carbonate: (29) describe using less than 5 percent by weight of potassium carbonate to eliminate caking. Read the entire page →

From page 7...

... 2-1 SECTION 2 SUMMARY OF CANDIDATE DEICER COMPONENTS EVALUATED IN TEST PROGRAM The initial phase of the research focused on identifying alternatives for four major deicer components based on their contributions to BOD and toxicity: • FPDs: 26 candidates • Thickeners: 5 candidates • Surfactants: 19 candidates • Corrosion Inhibitors: 17 candidates Also identified were two candidate anti-caking additives for use in sodium formate runway deicers and one candidate antifoam for use in deicing formulations. A combination of molecular modeling, database searches, and literature searches were used to identify candidates for each of these component classes.