Water solid interactions II. Effect of moisture sorption and glass transition temperature on compactibility of microcrystalline cellulose alone or in binary mixtures with polyvinyl pyrrolidone

Stubberud, Lars; Arwidsson, Hans; Larsson, Annika Taghizadeh; Graffner, Christina

doi:10.1016/0378-5173(95)04439-6

Cited by 35 publications

(32 citation statements)

References 24 publications

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“…We were not able to detect a glass transition calorimetrically, which was in agreement with several previous studies Roos 1995;Stubberud et al 1996), although not with the recent report by Szczesniak et al (2008). The first heat thermograms for both ball milled cellulose samples, softwood and eucalyptus, are shown in Fig.…”

Section: Calorimetric and Mechanical Transitions In Ball Milled Cellusupporting

confidence: 92%

The glass transition and crystallization of ball milled cellulose

et al. 2010

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Samples of ball milled cellulose were prepared by ball milling pulps from eucalyptus and softwood (spruce/pine). Water sorption isotherms were obtained by both dynamic vapor sorption and equilibration over saturated salt solutions, in the water content range of 5-42% db (db = dry basis; water as a % age of total solids). Dynamic mechanical analysis using a pocket technique showed a water content dependent thermal transition occurring at the same temperature for the two pulp samples, which was interpreted as a glass transition. Fitting the data to a Couchman-Karasz relationship predicted a value for T g of the dry cellulose of approximately 478 K, which was similar to values previously reported for other dry polysaccharides. No clear glass transition could be observed calorimetrically, although an endotherm at approximately 333 K was measured, which in polymers is normally attributed to enthalpic relaxation, however the lack of dependence of this endotherm on water content suggests that the melting of some weak associations, such as residual hydrogen bonds, could be a more credible explanation. An exotherm was also observed on heating, which was dependent on water content and which was attributed to partial crystallization of the cellulose. This was confirmed by Wide angle X-ray diffraction and cross polarization magic angle spinning 13C NMR (CPMAS NMR). The recrystallisation was predominantly to form I of cellulose. This was thought to be caused by a small amount of residual form I (probably less than 5%) acting as a template for the crystallizing material. Differential scanning calorimetry reheat curves showed the appearance of freezable water for water contents higher than 20%, as a result of a transfer of water to the amorphous phase following crystallization. The increase in cellulose rigidity following crystallization was also confirmed by CPMAS NMR relaxation. Low resolution proton NMR T 2 relaxation suggested the presence of proton water/cellulose exchange, which was active at water contents of 20% and above

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Section: Calorimetric and Mechanical Transitions In Ball Milled Cellusupporting

confidence: 92%

The glass transition and crystallization of ball milled cellulose

et al. 2010

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“…The tablets were stored either at 40°C/75% RH or in a refrigerator (4°C–8°C; served as control). The water content is expected to influence the tablet volumes and tensile strengths especially in the MCC‐containing tablets 19,20. Therefore, all the stored tablets, when sampled, were equilibrated under ambient conditions (∼20°C/40% RH, 48–72 h) before evaluation.…”

Section: Methodsmentioning

confidence: 99%

Phase Transformation in Thiamine Hydrochloride Tablets: Influence on Tablet Microstructure, Physical Properties, and Performance

Chakravarty

Suryanarayanan

Govindarajan

2012

Journal of Pharmaceutical Sciences

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“…7,8 Therefore, knowledge of the T g is very important in the characterization of MCC. Stubberud et al 9 were not able to determine the T g of MCC by differential scanning calorimetry (DSC) at standard heating rates. Batzer and Kreibich 10,11 found a T g of $2308C for dry cellulose, which decreased with increasing amounts of water.…”

Section: Introductionmentioning

confidence: 99%