Adsorption of non-ionic water-soluble cellulose polymers at the solid-water interface and their effect on suspension stability

Ultrasonic degradation for molecular weight reduction of pharmaceutical cellulose ethers

“…The correlation coefficient of r 2 = 0.99 is considered acceptable but the relatively limited number of samples and moderate polydispersity (preferably at least four samples of different molecular weight with P d < 1.75 are required) is not ideal for elucidation of M-H parameters (Brandrup et al, 2005). Reassuringly, the values of K = 3.47 × 10 −5 and a = 0.88 from this work were found to be comparable to those quoted by Law and Kayes (1983) of K = 6.25 × 10 −5 and a = 0.84. It is presumed however, that the M-H parameters given by Law and Kayes (1983) for HPC in water were not based on direct measurements, as the authors state that the M-H equation was established from data by Wirick and Waldman (1970) of HPC in ethanol.…”

“…Reassuringly, the values of K = 3.47 × 10 −5 and a = 0.88 from this work were found to be comparable to those quoted by Law and Kayes (1983) of K = 6.25 × 10 −5 and a = 0.84. It is presumed however, that the M-H parameters given by Law and Kayes (1983) for HPC in water were not based on direct measurements, as the authors state that the M-H equation was established from data by Wirick and Waldman (1970) of HPC in ethanol. M v results determined using the M-H exponents determined from Fig.…”

“…Despite the general agreement for measurements of [Á] in the literature, there exist some differences in the Mark-Houwink exponents used and thus the values quoted for determinations of the molecular weight of HPMC. The M-H parameters quoted originally by Dow Chemicals (1975) ( Table 1) have been used in a number of subsequent studies to determine the molecular weight of HPMC, for example, Law and Kayes (1983), Duro et al (1998) andWoolenweber, Makievski, Miller, andDaniels (2000), however these parameters appear to have been constructed from M n rather than M w data and therefore yield a molecular weight closer to the M n rather than M w . The use of M n rather than M w to obtain M-H parameters means the 'K' value of the M-H equation is much more influenced by the P d of the polymer samples, and caution should be exercised in using these relationships (Brandrup, Immergut, Grulk, Abe, & Bloch, 2005).…”

“…M v results determined using the M-H exponents determined from Fig. 5 and the [Á] for degraded and un-degraded HPC-EF samples (Table 2) gave molecular weights approximately 17% greater than those determined using those quoted by Law and Kayes (1983). Kulicke et al (2005) have published a list of M-H parameters for various cellulose derivatives.…”

Agglomeration of Celecoxib by Quasi Emulsion Solvent Diffusion Method: Effect of Stabilizer

“…11 In fact, the adsorption of stabilizer to the surface of the formed droplets, once the optimum packing of the stabilizer has been reached, can hinder coalescence of droplets through steric or electrostatic stabilization and thus droplets with smaller size and tight distribution are produced. [12][13][14][15] As mentioned above, the formation of finer and more homogeneous droplets, in turn, allows the formation of smaller particles with narrower PSD. It can be predicted that the nature of the stabilizer could be the main reason for the efficient formation of droplets and stabilization of the agglomerates.…”