Application of Ethoxylated Inulin in Water-Blown Polyurethane Foams

Biomacromolecules 2005, 6, 1992-1997

1992

Application of Ethoxylated Inulin in Water-Blown Polyurethane Foams Tina M. Rogge,† Christian V. Stevens,*,† Annelies Vandamme,‡ Karl Booten,‡ Bart Levecke,‡ Christiaan D’hooge,§ Bart Haelterman,§ and Johan Corthouts§ Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium, ORAFTI, Product Development Department, Aandorenstraat 1, B-3300 Tienen, Belgium, and INEOS N.V., Haven 1053, Nieuwe Weg 1, B-2070 Zwijndrecht, Belgium Received January 4, 2005; Revised Manuscript Received March 9, 2005

Inulin, a polydisperse reserve polysaccharide from chicory, was chemically modified via alkoxylation using ethylene oxide, in a water free medium. The reaction resulted in a range of products with very distinct properties, such as a highly increased water solubility, moderate surface-active properties and high cloud points in electrolyte media. Because of the unique characteristics of inulin, such as its molecular weight range, and because of the high water solubility of the ethoxylates, the products were evaluated as additive in water-blown polyurethane foams. The addition of inulin ethoxylates resulted in an increased foam hardness and density, the latter in fact being unwanted. The foam properties were evaluated based on the indentation test, the foam density, the SAG factor, and the hysteresis curves of standard cubes. Based on these parameters inulin ethoxylates were shown to have a beneficial effect on the foam properties. The inulin ethoxylate with a theoretical degree of substitution of 0.5 proved to be the best derivative, since the increase in hardness was the highest, while the increase in density was negligible. Introduction Chemical modification of polysaccharides has been investigated thoroughly during the last years because of the increased interest in the use of renewable resources for nonfood applications.1,2 Modification of polysaccharides is desirable to extend the amount and the type of functional properties, e.g., the water solubility or the hydrophilic/ hydrophobic balance (HLB), for use in food as well as nonfood industries. In detergent formulations, alkoxylation of polysaccharides can lead to interesting products to evaluate as a renewable alternative for some known, purely synthetic alkoxylates.3,4 Further, the use of polysaccharides could also lead to an increased biodegradability, compared to alkoxylates from synthetic origin. Via alkoxylation, the HLB can be changed considerably, depending on the required applications of the end products. The application of unmodified as well as modified polysaccharides in polyurethane foams has been studied and patented before. Research was performed to improve the foam properties and the biodegradability of the polyurethane foams. The influence of alkoxylated starch, glucose syrup, and sorbitol on the characteristics of polyurethane foams (PU foams), such as the end of rise and the tack free time, was described and resulted in a beneficial effect for the tested derivatives.5,6,7 Also flame retardancy can be influenced by additives, e.g., silicon surfactants, phosphorus containing * Corresponding author. E-mail: [email protected]. Tel.: +32 (0)9 264 59 57. Fax: +32 (0)9 264 62 43. † Ghent University. ‡ ORAFTI. § INEOS N.V.

additives, or saccharides, such as saccharose.8,9 Not only flexible foams but also rigid PU foams can be prepared with saccharides, such as xylose, mannitol, and sorbitol.10 Inulin is the reserve polysaccharide of chicory (Cichorium intybus) and consists mainly of β(2-1) fructosyl fructose units (Fm) with normally, but not always, a glucopyranose at the reducing end (GFn). This biopolymer has been the subject of several chemical modifications due to its interesting properties, mainly for producing bio-based surfactants or calcium chelating agents.11,12 Earlier research by our group led to the ethoxylation and propoxylation of inulin in quantitative yields (Figure 1).13 The inulin derivatives all showed some distinct properties, like very high cloud points, moderate surface active properties, and a considerable increase in water solubility at room temperature (up to 85%) compared to native inulin (2%). Materials and Methods Materials. Inulin (INUTECN25) was supplied by ORAFTI (Tienen, Belgium) and was used after ethoxylation as described in earlier research.13 The mean degree of polymerization was approximately 25 and was determined by HPLC analysis after enzymatic hydrolysis.14 Dimethyl imidazole was purchased at Acros and was used as 80% (w/w) solution in water. The trifunctional polyol (PEG, PPG polymer) was supplied by INEOS (Zwijndrecht, Belgium), had an OH value of 29.4, and was used as such, without further purification. MDI (diphenylmethane diisocyanate, with NCO value of 32.6) was purchased from Huntsman and was used as received.

10.1021/bm050006m CCC: $30.25 © 2005 American Chemical Society Published on Web 05/11/2005

Application of Ethoxylated Inulin in PU Foams

Biomacromolecules, Vol. 6, No. 4, 2005 1993

Figure 1. Synthesis of alkoxylated inulin. Table 1. Calculated Hydroxyl Values of Inulin and Its Derivatives additive

OH value (mg KOH/ g)

inuline (HP) I + 0.1 equiv. EOa I + 0.5 equiv. EO I + 1.0 equiv. EO I + 2.0 equiv. EO I + 6.0 equiv. EO I + 20 equiv. EO I + 45 equiv. EO

1039 1011 915 817 673 395 161 78

I + x equiv. EO ) inulin ethoxylated with x equivalents of ethylene oxide (EO). a

Methods. Preparation of the Standard Foam. The standard reference foam, which had a water index of 150, was prepared starting from 162.5 g of polyol, 87.5 g of isocyanate (diphenylmethane diisocyanate MDI, with a NCO value of 32.6), 1.25 g of dimethyl imidazole in water (80% w/w), and 7.78 g of water. The second reference foam, which had a water index of 147, was prepared starting from 189.4 g of polyol, 97.58 g of isocyanate (MDI), 1.15 g of dimethyl imidazole in water (80% w/w), and 8.3 g of water. No further additives were used that could influence the foam properties. The amounts for the foam with an index of 150 were calculated as follows: gwater for index 150 ) NCOvalue * NCOamount - (Σ OHvalue * OHamount) 42/561 1.5* 6233.3 where NCOvalue ) isocyanate value of the used isocyanate (32.6% (w/w)); NCOamount ) the amount of isocyanate (in g); OHvalue ) the hydroxyl values (in mg KOH/g) of all the used alcohols (6233.3 for water, 29.4 for the polyol, see Table 1 for ethoxylated inulin); OHamount ) the amount of alcohols (in g). The starting blend for the foam (water, polyol, and catalyst) was mixed for 20 s, and after addition of the isocyanate, an extra mixing step of 10 s was applied. After the mixing step the blend was poured into a standard plastic bucket with a diameter of 17 cm, in which the foam could cure at room temperature and the “end of rise” time was measured as one of the first characteristics. Preparation of PU Foams with Ethoxylated Inulin as AdditiVe. a. Constant Amount of Water and a Variable Water Index. When the amount of water is kept constant at 8.02 g

(7.77 g added as such and 0.25 g coming from the catalyst solution) and alkoxylated inulin is added to the formulation, the water index of the foam changes. This change in water index can be calculated as follows (water index ) 100X): NCOvalue * NCOamount - (Σ OHvalue * OHamount) 42/561 8.02 ) X * 6233.3 Here too a mixing step of 20 s was applied for the starting blend (polyol, water in which the inulin derivatives were dissolved, and catalyst) as well as an extra mixing step of 10 s after the addition of the isocyanate. b. Constant Water Index and Variable Amounts of Water and Inulin Ethoxylate. The equations shown above are used to calculate the amount of water necessary to obtain a certain water index when, e.g., 2.0 g of inulin ethoxylate is added to the formulation. Sample Preparation for Density, Hardness, and Hysteresis Measurements. From the prepared foams, a small cube was cut with standard length, width, and height of 10 × 10 × 5 cm from the center of the foam and at 10 cm from the bottom of the foam. All foam tests were performed in triplicate (the mean values are presented) at constant temperature and air moisture. a. Density Measurements. The standard cubes were weighed and the density was calculated. b. Indentation Test. The cube was compressed to 30% of its original height (indentation of 70%) and the measurements were accomplished at the third cycle of indentation and relaxation. The forces at 25, 40, and 65% indentation were noted, and the SAG factor (force at 65%/force at 25%), the indentation hardness (force at 40%), and the hysteresis (in %) were calculated. The measurements were performed at a TA-XT2i and the disc-shaped indenter had a diameter of 7.5 cm. Results and Discussion Because of the huge increase in water solubility (up to 85% at RT) of the alkoxylated inulin in comparison to the native inulin (2%), the ability of the derivatives to influence the properties of polyurethane foams was evaluated. Native inulin was also evaluated, but due to its low solubility at room temperature it is not possible to add a sufficient amount of the polyol as a solution in water. To obtain a good

1994

Biomacromolecules, Vol. 6, No. 4, 2005

Rogge et al.

Table 2. Characteristics of PU Foams with Inulin Alkoxylates as Additives (Constant Water Index of 150) additive

additive (g)

end of rise

blow off a

density (kg/m)

hardness (g)

hysteresis loss (%)

SAG factor

height (cm)

inulin HP inulin + 0.1 equiv. EO inulin + 0.5 equiv. EO inulin + 0.5 equiv. EO inulin + 0.5 equiv. EO inulin + 1 equiv. EO inulin + 1 equiv. EO inulin + 2 equiv. EO inulin + 2 equiv. EO inulin + 6 equiv. EO inulin + 6 equiv. EO inulin + 20 equiv. EO inulin + 20 equiv. EO inulin + 45 equiv. EO inulin + 45 equiv. EO inulin + 45 equiv. EO

2.0 2.0 2.0 6.0 12.0 2.0 6.0 2.0 6.0 2.0 6.0 2.0 6.0 2.0 6.0 12.0

1′43 2′04 2′05 1′50 2′14 2′25 1′47-2′00 2′20 2′00 2′07 1′59 2′09 2′03 2′09 2′02 2′08 2′12

N N Y N 2′00 N N N 1′47 1′48 1′47 1′56 1′14 N 1′07-1′20 1′45 N

34.02 32.6 37.6 38.2 41.7 45.2 37.0 42.0 35.2 39.0 50.6 38.8 34 34.8 33.0 34.4 33.8

2970 2866 3499 3477 4198 4573 3332 3922 3477 2789 2822 2984 2676 2400 2665 1921 1417

15.5 16.4 15 15 14 13.4 15 14 15 15.5 16.5 15.6 16.5 15.4 15 13 11

2.43 2.6 2.51 2.5 2.44 2.58 2.48 2.5 2.5 2.43 2.38 2.48 2.32 2.28 2.5 2.5 2.7

25 27 25 26.5 24 24 25.5 25 25 25 26 25 26 25 27 26 27

a

N means there was no blow off during the curing of the foam; otherwise the time is reported at which the blow off occurred.

Figure 2. Foams with serious bottom defect, containing 2 g of I + 20 equiv. EO (a), the reference foam (b) and without defect, foam containing 2 g of I + 0.1 equiv. EO (c).

understanding of the effect of the alkoxylated inulin, the derivatives were added in a systematic way to a standard polyurethane formulation. When the amount of polyol, isocyanate, and catalyst is constant, the properties of a PU foam can be strongly influenced by the amount of water, which is expressed by the water index of a polyurethane foam. When a formulation is made with the same ratio polyol/isocyanate but with a higher amount of water, the foams will have a higher water index and will probably have a higher ratio hardness/density. This ratio shows a linear coarse and the slope of the curve can probably be substantially influenced by addition of inulin ethoxylates. Due to their high hydroxyl value, small amounts could have a huge influence on the properties. To characterize the effect of a polyol in polyurethane foams, a standard hydroxyl value is defined for the used polyols; this is the amount of potassium hydroxide, necessary for the saponification reaction of the corresponding ester. The hydroxyl value of alkoxylated inulin was calculated as follows and was expressed in mg KOH/g sample: OH value )

56100f MW

where f ) functionality (for inulin and derivatives: 3 per

fructose unit) and MW ) molecular weight (for inulin: weight of one fructose unit (-water) or 162 g/mol). Some theoretical hydroxyl values of ethoxylated inulin derivatives were calculated with the formula mentioned above (Table 1), which were also determined experimentally via titration according to the ASTM method D 2849-69, using phthalic anhydride and pyridine.15 The experimental values did not differ from the theoretical values (maximum deviation was 10%). The following inulin ethoxylates were synthesized according to the published procedure: inulin + 0.1, 0.5, 1.0, 2.0, 6.0, and 45.0 equivalents of ethylene oxide.13 All of these derivatives were evaluated as additives in water-blown polyurethane foams. A standard polyurethane foam was prepared with a water index of 150 and a polyol/isocyanate ratio of 65/35. The end of rise of the reference foam was 1 min 43 s, so there was no collapse and only minor blow off (Table 2). The hardness of the reference foam was 2970 kg, and its density was 34 kg/m3. The comfort or SAG factor was 2.43, which can be considered as being a highly elastic foam.16 The SAG factor of most foams ranges from 2.0 (very low) to 3.0 (very high). Any foam having a SAG factor less than 2.0 is usually a foam with poor quality, which most likely indicates a poor formulation. To this standard foam were added inulin



Figure 3. Influence of the different inulin ethoxylates on the density, hardness and SAG factor (water index 150).

ethoxylates as a solution in water in order to get a detailed view on the influence of alkoxylated inulin on the properties of the polyurethane foams. Since a change in water index can already have a huge influence on the properties of a PU foam, it is necessary to adjust the water amount to obtain foams with the same water index as the reference foam but with inulin alkoxylates as additive. Comparing the properties of both types of foams with the reference, it is possible to

get a good understanding on the influence of the inulin alkoxylates. Table 2 describes the characteristics of the foams during preparation (height, blow off, and end of rise time) and the measured properties of the cubes (hysteresis, density, hardness, and SAG factor), of several PU foams, with a water index of 150 and 2.0, 6.0, or 12.0 g of inulin ethoxylate. The reference foam shows a minor blow off, has small ruptures in its skin, and shows some bottom defect, which is rather negligible (see Figure 2). All of these minor deficiencies of the reference can either be increased by addition of inulin ethoxylates or can be decreased or even eliminated. It is clear from the data of Table 2 that the inulin ethoxylates improved the basic foam properties of the reference foam. Figure 3 shows the results of the indentation and density tests. It can be concluded that the lower degrees of substitution of the ethoxylated inulin result in harder foams, which have a higher density, whereas the higher degrees of substitution lead to softer foams, which have the same density as the reference foam. However, it has to be mentioned that the increase in hardness is a lot higher than the increase in density, which is favorable, because the perfect additive should lead to a stronger and harder, but not a denser foam. For the inulin derivative with a DS of 0.5, the increase in hardness is approximately 57%, whereas the density increases only 33%. In the automotive seating industry, convention holds that the density of a PU foam is strongly related to its overall durability. As foam density is increased in a given seat system, durability performance is thought to improve. Therefore, seat system suppliers attempt to control long-term complete seat comfort and appearance by constraining foam densities. This density to performance trend is generally true; however, recent studies have shown that foams of the same density may have a different performance based on additives and processing. These discoveries led to the postulate that although foam density

Table 3. Characteristics of the PU Foams with Variable Water Index (Constant Water Amount of 7.77 g) additive

water index

additive (g)

end of rise

blow off a

density (kg/m)

hardness (g)

hysteresis loss (%)

SAG factor

height (cm)

inulin HP inulin + 0.1 equiv. EO inulin + 0.1 equiv. EO inulin + 0.5 equiv. EO inulin + 0.5 equiv. EO inulin + 0.5 equiv. EO inulin + 1 equiv. EO inulin + 1 equiv. EO inulin + 1 equiv. EO inulin + 1 equiv. EO inulin + 2 equiv. EO inulin + 2 equiv. EO inulin + 6 equiv. EO inulin + 6 equiv. EO inulin + 20 equiv. EO inulin + 20 equiv. EO inulin + 45 equiv. EO inulin + 45 equiv. EO inulin + 45 equiv. EO

150 160 160 183.5 159 180 224 157.8 176 212.5 268.5 156.3 171 154 162 151.5 155 151 152 154

0 2.0 2.0 6.0 2.0 6.0 12.0 2.0 6.0 12.0 18.0 2.0 6.0 2.0 6.0 2.0 6.0 2.0 6.0 12.0

1′43 2′03 1′50 1′50 1′44 1′50 2′25 1′36 1′50 2′20-2′35 2′30 1′55 1′55 2′02 2′02 2′00 2′03 1′52 2′07 2′02

N 1′45 1′40 1′35 N N 1′39 N N N N 1′38 1′39 N 1′46 1′14 1′47 1′07 1′34 N

34.02 36.4 35.7 33.6 37.8 39.0 41.3 37.0 40.8 41.2 41.2 34.2 37.4 33.6 38.2 33.4 33.2 34 35.2 32.8

2970 2896 3107 2831 3520 3377 4076 3876 2662 4020 6093 2515 2650 2539 2865 2664 2057 2234 2163 1447

15.5 16.2 16 15 15.5 18.0 22.4 16 14 15 14 15.63 17.1 16.1 15.6 15.15 15.5 15.1 15.2 15.4

2.43 2.37 2.44 2.49 2.47 2.4 2.32 2.55 2.47 2.52 2.59 2.49 2.65 2.48 2.5 2.33 2.43 2.44 2.4 2.66

25 27 27 27 25.5 25.5 24 26.5 24.5 24.5 23 26 26 27 26 26 25 27.5 26 28

a


1996

Biomacromolecules, Vol. 6, No. 4, 2005

Rogge et al.

Table 4. Characteristics of PU Foams with a Water Index of 147 additive

additive (g)

end of rise time

blow offa

density (kg/dm)

hardness (g)

hysteresis loss (%)

SAG factor

height (cm)

inulin + 0.1 equiv. EO inulin + 0.5 equiv. EO inulin + 0.5 equiv. EO inulin + 1.0 equiv. EO inulin + 1.0 equiv. EO

0 2.0 2.0 12.0 2.0 12.0

1′57 2′15 2′20 3′32 2′10-2′15 3′24

1′25 2′00 2′05 N 2′00 3′00

36.2 38.0 39.6 51.8 38.9 50.6

3000 3533 3619 5991 3527 5633

15.5 15.5 15 13.5 14.5 14

2.43 2.38 2.47 2.5 2.5 2.48

27 27 27.5 24 28 24

a


is an important factor determining the mechanical durability, it does not quantify other factors affecting foam durability. The loss of hysteresis may determine the foam durability in a better way. This test measures the percentage of energy, lost during a compression cycle of the foam. It suggests that a lower number is better for foam durability, since the foam itself absorbs less energy at a lower hysteresis loss. The hysteresis loss test is composed of several factors affecting durability, including density and foam formulation.17 The hysteresis loss of the reference foam was 15.5% compared to 16.5% when adding native inulin and was slightly diminished to 15% when adding inulin ethoxylates with low degrees of substitution (DS < 1.0). The decrease in hysteresis loss was maximal for the ethoxylated inulin with a DS of 0.5 (down to 13.5% when adding 12 g). For all of the derivatives, the so-called comfort factor or the SAG factor (the ratio of the force for an indentation of 65% over the force for an indentation of 25%) is always near the reference value of 2.5. From the data, it can also be concluded that adding 2 g of inulin ethoxylates with a DS of 0.1 or 0.5 can lead to the optimal SAG factor. The changes that are observed in the foams with inulin alkoxylates as additives could also be explained as a “polyol effect” (which is a change in properties of the foam by the presence of large amounts of hydroxyl functions in the formulation). Therefore, a series of standard foams without inulin alkoxylate, but with an equivalent level of hydroxyl groups by an increase in standard polyol, were prepared. Considering just some basic parameters, such as the “end of rise” time, it was clear that the influence of inulin alkoxylates compared to the standard polyol is considerable. Table 3 describes the properties of PU foams, including the ethoxylated inulin derivatives with a varying water index. The most effective additives considering the hardness and density are the inulin ethoxylates with a DS of 0.5 and 1.0. The derivatives with a DS of 20 and 45 led to a huge decrease in hardness (down to 50%). When considering the hysteresis losses for the PU foams with a variable water index, the difference in influence of the derivatives with lower degrees of substitution and those with a higher DS is not that distinct. The changes in hysteresis loss could be attributed to the change in water index, since the effect of the derivatives on the water index is strongly dependent on the DS. After all, ethoxylated inulin has a very high hydroxyl value. When preparing PU foams with a similar water index as compared to the ones with inulin ethoxylates (e.g., 268.5), it was no longer possible to produce stable foams which did not collapse before curing.

Figure 4. Influence of the different inulin ethoxylates on the density, hardness and SAG factor (variable water index).

The inulin ethoxylates with the highest and most favorable impact on the reference foam were also tested in a formulation with a constant water index of 147 (cf. Table 4). From the results in Table 4, it can be concluded that again the derivatives with a lower theoretical degree of substitution led to a distinct increase in the hardness of the foam and that the ones with a higher DS resulted in rather soft foams. All derivatives resulted in foams with good skins and almost no bottom defect. When the water index of the foam was increased, in the same ratio as happens when adding inulin ethoxylates, it was no longer possible to produce stable foams, which do not collapse completely. From Figure 4, it can be concluded that the introduction of inulin ethoxylates leads to an increase in hardness, and an optimal comfort factor of 2.5 can be obtained. For the inulin ethoxylate with a DS of 0.5, the hardness increases 100%, whereas the density only increases 39%; for the other derivatives the



is used as a parameter to estimate the lifetime of a PU foam, was most distinct for the inulin ethoxylate with a DS of 0.5. When varying the water index (keeping the water amount constant and adding ethoxylated inulin), the derivative with a DS of 1.0 resulted in the highest increase in hardness. All inulin derivatives with low degrees of substitution had a beneficial effect on the hysteresis losses of the foam, which indicates that in general the lifetime of the PU foam can be increased when adding the inulin ethoxylates. In almost every case, the appearance of the foams was better than the reference, since the skin showed no ruptures and there was little or no bottom defect present when adding ethoxylated inulin. Therefore, it can be concluded that the introduction of modified inulin derivatives to polyurethane formulations has a favorable effect on the foam properties. Acknowledgment. The authors are indebted to the IWT (Instituut voor de Aanmoediging van Innovatie door Wetenschap en Technologie in Vlaanderen - Flemish Institute for the Promotion of Scientific-Technological Research in Industry) for the financial support to the companies INEOS and ORAFTI and to Ghent University. References and Notes

Figure 5. Influence of the different inulin ethoxylates on the density, hardness, and SAG factor (water index 147).

influence on the properties is less distinct. From Table 4, it is clear that the derivative with a DS of 0.5 has the major influence, since the hysteresis losses can be decreased to 13.5%. Conclusion After addition of inulin alkoxylates to the polyol for the preparation of PU foams, an obvious increase in hardness, but also an increase in density was observed. When keeping the water index constant at 150, the increase in hardness was more pronounced than the increase in density for the foams including an inulin ethoxylate with a theoretical degree of substitution of 0.1 or 0.5. This phenomenon was less explicit for the other inulin alkoxylates with a higher DS. However, when adding 45 equiv. of ethylene oxide to the inulin backbone, the increase in hardness becomes more pronounced again. The decrease in hysteresis losses, which

(1) Geiser, K. Materials Matter; The MIT Press: Cambridge, MA, 2001; p 479. (2) Stevens, C. V.; Verhe´, R. Renewable Bioresources, Scope and Modification for Nonfood Applications; John Wiley & Sons: London, 2004; p 310. (3) Balson, T.; Felix, M. S. B. Biodegrad. Surfactants 1995, 204. (4) Naylor, C. G.; Castald, F. J.; Barbara, J. J. Am. Oil Chem. Soc. 1988, 65, 1669. (5) Meerbote, M.; Mosinski, H.; Schiller, K.; DE 19924771, 2000. (6) Dinsch, S.; Heinz, M.; Winkler, J.; Rotermund, U.; Biedermann, A.; Kampf, G. DE 10237914, 2004. (7) Guettes, B.; Hinz, W.; Hempel, R.; Rotermund, U.; Wetterling, M. DE 19824134, 1998. (8) Leake, J. S.; Law, P. W. WO 9421724, 1994. (9) Weier, A.; Burkhart, G.; Klincke, M. R. Soc. Chem. Ind. Appl. Surf. IV 1999, 23, 260-271. (10) Barber, T. A. WO 2004060948, 2004. (11) Stevens, C. V.; Meriggi, A.; Booten, K. Biomacromolecules 2001, 2, 1-16. (12) Stevens, C. V.; Meriggi, A.; Peristeropoulou, M.; Christov, P. P.; Booten, K.; Levecke, B.; Vandamme, A.; Pittevils, N.; Tadros, T. F. Biomacromolecules 2001, 2, 1256. (13) Rogge, T. M.; Stevens, C. V.; Booten, K.; Levecke, B.; Vandamme, A.; Vercauteren, C.; Haelterman, B.; Corthouts, J.; D’hooge, C. Top. Catal. 2004, 1-4, 39. (14) Hoebregs, AOACS methods nr 997.08, J. AOAC int., 1997; Vol. 80, p 1029. (15) ANSI/ASTM D 2849-69, Standard Method of Testing Urethane Foam Polyol Raw Materials; Part 36, American Society for Testing and Materials: Philadelphia, PA, 1979. (16) Arlt, A.; Wagner, K.; Varenkamp, V. EP 20020515, 2002. (17) LeFever, A.; McEvoy, J.; Conf. Proc. Polyurethanes Expo. 2001, 275.

BM050006M

Application of Ethoxylated Inulin in Water-Blown Polyurethane Foams

Recommend Documents