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AAPS PharmSciTech. 2003 December; 4(4): 469–479.
Published online 2003 September 18. doi:  10.1208/pt040460
PMCID: PMC2750653

Studies on the interaction of water with ethylcellulose: Effect of polymer particle size


The purpose of this research was to investigate the interaction of water with ethylcellulose samples and assess the effect of particle size on the interaction. The distribution of water within coarse particle ethylcellulose (CPEC; average particle size 310 μm) and fine particle ethylcellulose (FPEC; average particle size 9.7 μm) of 7 cps viscosity grade was assessed by differential scanning calorimetry (DSC) and dynamic vapor sorption analysis. The amounts of nonfreezing and freezing water in hydrated samples were determined from melting endotherms obtained by DSC. An increase in water content resulted in an increase in the enthalpy of fusion of water for the two particle size fractions of EC. The amount of nonfreezable water was not affected by the change in particle size at low water contents. Exposure of ethylcellulose to water for 30 minutes is sufficient to achieve equilibration within the hydrated polymer at 47% wt/wt water content. The moisture sorption profiles were analyzed according to the Guggenheim-Anderson-de Boer (GAB) and Young and Nelson equations, which can help to distinguish moisture distribution in different physical forms. The amount of externally adsorbed moisture was greater in the case of FPEC. Internally absorbed moisture was evident only with the CPEC. In light of these results, and explanation is offered for the success of FPEC in wet-granulation methods where CPEC was not successful.

Keywords: ethylcellulose, fine particle ethylcellulose, differential scanning calorimetry, dynamic vapor sorption, GAB equations, Young and Nelson equations

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Selected References

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1. Nakamura K, Hatakeyama T, Hatakeyama H. Studies on bound water of cellulose by differential scanning calorimetry. Text Res J. 1981;51:607–613. doi: 10.1177/004051758105100909. [Cross Ref]
2. Nakamura K, Hatakeyama T, Hatakeyama H. Relationship between hydrogen bonding and bound water in polyhydroxystyrene derivatives. Polymer. 1983;24:871–876. doi: 10.1016/0032-3861(83)90206-9. [Cross Ref]
3. Hatakeyama H, Hatakeyama T. Interaction between water and hydrophilic polymers. Thermochim Acta. 1998;308:3–22. doi: 10.1016/S0040-6031(97)00325-0. [Cross Ref]
4. Joshi NH, Topp EM. Hydration in hyaluronic acid and its esters using differential scanning calorimetry. Int J Pharm. 1992;80:213–225. doi: 10.1016/0378-5173(92)90279-B. [Cross Ref]
5. Joshi NH, Wilson TD. Calorimetric studies of dissolution of hydroxypropyl methylcellulose E5 (HPMC E5) in water. J Pharm Sci. 1993;82:1033–1038. doi: 10.1002/jps.2600821011. [PubMed] [Cross Ref]
6. McCrystal CB, Ford JL, Rajabi-Siahboomi AR. A study on the interaction of water and cellulose ethers using differential scanning calorimetry. Thermochim Acta. 1997;294:91–98. doi: 10.1016/S0040-6031(96)03148-6. [Cross Ref]
7. McCrystal CB, Ford JL, Rajabi-Siahboomi AR. Water distribution studies within cellulose ethers using differential scanning calorimetry. 1. Effect of polymer molecular weight and drug addition. J Pharm Sci. 1999;88(8):792–796. doi: 10.1021/js9804258. [PubMed] [Cross Ref]
8. McCrystal CB, Ford JL, Rajabi-Siahboomi AR. Water distribution studies within cellulose ethers using differential scanning calorimetry. 2. Effect of polymer substitution type and drug addition. J Pharm Sci. 1999;88(8):797–801. doi: 10.1021/js9804260. [PubMed] [Cross Ref]
9. Bhaskar G, Ford JL, Hollingsbee DA. Thermal analysis of the water uptake by hydrocolloids. Thermochim Acta. 1998;322:153–165. doi: 10.1016/S0040-6031(98)00493-6. [Cross Ref]
10. Ford JL. Thermal analysis of hydroxypropylmethylcellulose and methylcellulose: powders, gels and matrix tablets. Int J Pharm. 1999;179:209–228. doi: 10.1016/S0378-5173(98)00339-1. [PubMed] [Cross Ref]
11. McCrystal CB, Ford JL, He R, Craig DQ, Rajabi-Siahboomi AR. Characterisation of water behaviour in cellulose ether polymers using low frequency dielectric spectroscopy. Int J Pharm. 2002;243:57–69. doi: 10.1016/S0378-5173(02)00275-2. [PubMed] [Cross Ref]
12. Fielden KE, Newton JM, O'Brien P, Rowe RC. Thermal studies on the interaction of water and microcrystalline cellulose. J Pharm Pharmacol. 1988;40:674–678. [PubMed]
13. Hollenbeck RG, Peck GE, Kildsig DO. Application of immersional calorimetry to investigation of solid-liquid interactions: microcrystalline cellulose-water system. J Pharm Sci. 1978;67(11):1599–1606. doi: 10.1002/jps.2600671125. [PubMed] [Cross Ref]
14. Zografi G, Kontny MJ, Yang AYS, Brenner GS. Surface area and water vapor sorption of microcrystalline cellulose. Int J Pharm. 1984;18:99–116. doi: 10.1016/0378-5173(84)90111-X. [Cross Ref]
15. Malamataris S, Karidas T, Goidas P. Effect of particle size and sorbed moisture on the compression behaviour of some hydroxypropyl methylcellulose (HPMC) polymers. Int J Pharm. 1994;103:205–215. doi: 10.1016/0378-5173(94)90170-8. [Cross Ref]
16. Nokhodchi A, Ford JL, Rubinstein MH. Studies on the interaction between water and (hydroxypropyl)methylcellulose. J Pharm Sci. 1997;86(5):608–615. doi: 10.1021/js960279a. [PubMed] [Cross Ref]
17. de Boer JH. The Dynamic Character of Adsorption. 2nd ed. London, UK: Clarendon Press; 1968.
18. Sadeghnejad GR, York P, Stanley-Wood NG. Water vapor interaction with pharmaceutical cellulose powders. Drug Dev Ind Pharm. 1986;12:2171–2192. doi: 10.3109/03639048609042629. [Cross Ref]
19. Young JH, Nelson GL. Theory and hysteresis between sorption and desorption isotherms in biological materials. Trans Am Soc Agric Eng. 1967;10:260–263.
20. Young JH, Nelson GL. Research and hysteresis between sorption and desorption isotherms of wheat. Trans Am Soc Agric Eng. 1967;10:756–761.
21. York P. Analysis of moisture sorption hysteresis in hard gelatin capsules, maize starch, and maize starch: drug powder mixtures. J Pharm Pharmacol. 1981;33:269–273. [PubMed]
22. Eisenberg D, Kauzman W. The structure and properties of water. London, UK: Oxford University Press; 1969.
23. Zografi G, Kontny MJ. The interactions of water cellulose-and starch-derived phamaceutical excipients. Pharm Res. 1986;3:187–194. doi: 10.1023/A:1016330528260. [PubMed] [Cross Ref]
24. Ford JL, Mitchell K. Thermal analysis of gels and matrix tablets containing cellulose ethers. Thermochim Acta. 1995;248:329–345. doi: 10.1016/0040-6031(94)01954-F. [Cross Ref]
25. Sission WA. Aviced, Microcrystalline Cellulose, Its Production, Properties and Applications. Philadelphia, PA: FMC Corp; 1966.
26. Agrawal AM, Neau SH, Bonate PL. Wet granulation fine particle ethylcellulose tablets: effect of production variables and mathematical modeling of drug release.AAPS PharmSci. 2003;5(2):article 13. [PMC free article] [PubMed]
27. Zografi G, Carstensen JT, Kontny MJ, Attarchi F. The sorption of water vapour by starch and the application of the Young and Nelson equations. J Pharm Pharmacol. 1983;35:455–458. [PubMed]
28. Chans SY, Pilpel N. Absorption of moisture by sodium cromoglycate and mixtures of sodium cromoglycate and lactose. J Pharm Pharmacol. 1983;35:477–481. [PubMed]
29. Malamataris S, Goidas P, Dimitriou A. Moisture sorption and tensile strength of some tableted direct compression excipients. Int J Pharm. 1991;68:51–60. doi: 10.1016/0378-5173(91)90126-9. [Cross Ref]

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