Unified compaction curve model for tensile strength of tablets made by roller compaction and direct compression

2008 ◽  
Vol 346 (1-2) ◽  
pp. 17-24 ◽  
Author(s):  
Leon Farber ◽  
Karen P. Hapgood ◽  
James N. Michaels ◽  
Xi-Young Fu ◽  
Robert Meyer ◽  
...  
1855 ◽  
Vol 145 ◽  
pp. 225-242

It has been long known, that under the existing theory of beams, which recognizes only two elements of strength, namely, the resistances to direct compression and extension, the strength of a bar of cast iron subjected to transverse strain cannot be reconciled with the results obtained from experiments on direct tension, if the neutral axis is in the centre of the bar. The experiments made both on the transverse and on the direct tensile strength of this material have been so numerous and so carefully conducted, as to admit of no doubt of their accuracy; and it results from them, either that the neutral axis must be at, or above, the top of the beam, or there must be some other cause for the strength exhibited by the beam when subjected to transverse strain.


Marine Drugs ◽  
2020 ◽  
Vol 18 (2) ◽  
pp. 115 ◽  
Author(s):  
Deeb Abu Fara ◽  
Linda Al-Hmoud ◽  
Iyad Rashid ◽  
Babur Z. Chowdhry ◽  
Adnan Badwan

Chitin has been investigated in the context of finding new excipients suitable for direct compression, when subjected to roller compaction. Ball milling was concurrently carried out to compare effects from different energy or stress-inducing techniques. Samples of chitin powders (raw, processed, dried and humidified) were compared for variations in morphology, X-ray diffraction patterns, densities, FT-IR, flowability, compressibility and compactibility. Results confirmed the suitability of roller compaction to convert the fluffy powder of raw chitin to a bulky material with improved flow. X-ray powder diffraction studies showed that, in contrast to the high decrease in crystallinity upon ball milling, roller compaction manifested a slight deformation in the crystal lattice. Moreover, the new excipient showed high resistance to compression, due to the high compactibility of the granules formed. This was correlated to the significant extent of plastic deformation compared to the raw and ball milled forms of chitin. On the other hand, drying and humidification of raw and processed materials presented no added value to the compressibility and compactibility of the directly compressed excipient. Finally, compacted chitin showed direct compression similarity with microcrystalline cellulose when formulated with metronidazole (200 mg) without affecting the immediate drug release action of the drug.


2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Pavlína Vodáčková ◽  
Barbora Vraníková ◽  
Petra Svačinová ◽  
Aleš Franc ◽  
Jan Elbl ◽  
...  

As coprocessed excipients (CPE) gain a lot of focus recently, this article compares three commercially available CPE of Avicel brand, namely, CE 15, DG, and HFE 102. Comparison is based on measured physical properties of coprocessed mixtures, respectively, flow properties, pycnometric density, mean particle size, specific surface area, moisture content, hygroscopicity, solubility, pH leaching, electrostatic charge, SEM images, and DSC. Tablets were made employing three pressure sets. Viscoelastic properties and ejection force were assessed during compression, as well as pycnometric density, mass uniformity, height, tensile strength, friability, disintegration, and wetting times. Avicel CE 15 is of mid-range flow properties, contains mid-size and nonspherical particles, and has high hygroscopicity, growing negative charge, best lubricity, lowest tensile strength, and mid-long disintegration times. Avicel DG possesses the worst flow properties, small asymmetrical particles, lowest hygroscopicity, stable charge, intermediate lubricity, and tensile strength and exhibits fast disintegration of tablets. Finally, Avicel HFE 102 has the best flow properties, large symmetrical particles, and middle hygroscopicity and its charge fluctuates throughout blending. It also exhibits inferior lubricity, the highest tensile strength, and slow disintegration of tablets. Generally, it is impossible to select the best CPE, as their different properties fit versatile needs of countless manufacturers and final products.


2018 ◽  
Vol 44 (12) ◽  
pp. 2038-2047 ◽  
Author(s):  
Deeb Abu Fara ◽  
Iyad Rashid ◽  
Khouloud Alkhamis ◽  
Mahmoud Al-Omari ◽  
B. Z. Chowdhry ◽  
...  

2013 ◽  
Vol 9 (2) ◽  
pp. 155-161
Author(s):  
Aziana Azlin Abdul Hamid ◽  
Yus Aniza Yusof ◽  
Nyuk L. Chin ◽  
Suhaila Mohamed ◽  
Faiqa Salleh

AbstractThis study investigated the direct compression properties of Eurycoma longifolia Jack tablets using binary mixtures such as microcrystalline cellulose (mcc) and κ-carrageenan (carr). The mixtures were compacted to various compression pressures ranging from 7.5 to 74 MPa at a constant compression speed of 5 mm/min. The tensile strengths of the tablets were determined by a diametral compression test. A linear relationship between the tensile strength and the compression pressure was observed under the conditions of the test; hence, the slopes of the data were obtained by fitting linear trend lines. This paper shows that binary mixtures of 30% mcc and 70% Eurycoma longifolia Jack give the highest values for constant (a slope) compared with the other binary mixtures of both binders. Thus, this approach can be used to develop formulations for Eurycoma longifolia Jack tablets.


2017 ◽  
Vol 16 (10) ◽  
pp. 2341-2347
Author(s):  
Emmanuel O. Olorunsola ◽  
Stephen O. Majekodunmi

Purpose: To develop an extended-release formulation of domperidone using a blend of Raphia hookeri gum and hydroxypropyl methylcellulose as tablet matrix.Methods: Tablets (400 mg) containing 30 mg domperidone (DPD) were formulated using binary mixtures of hydroxypropyl methylcellulose (HPMC) and Raphia hookeri gum (RHG) as matrix former; and microcrystalline cellulose (MCC) as direct compression excipient. The proportions of the matrix formers (40 % of tablet weight) was varied as 100:0, 75:25, 50:50, 25:75 and 0:100. The composition of the matrix former was also kept constant (50:50) while MCC was varied as 40, 30, 20 and 10 %. The tablets were evaluated for compact density, tensile strength, friability and drug release over 24 h.Results: The tensile strength of tablets decreased while their friability increased with increase in the proportion of RHG. A similar trend was observed with decrease in the concentration of MCC. Tablets containing RHG alone as matrix former and 40 % MCC as direct compression excipient had tensile strength of 0.95 MNm-2, friability of 1.07 % and cumulative drug release of 83.2 % over a period of 24 h. Tablets containing equal proportions of HPMC and RHG as matrix former had the best release properties of 95.0 % over a period of 24 h.Conclusion: RHG is comparable with HPMC in terms of extending the release of  domperidone for a once daily administration. A suitable combination of the two  polymers for use as a matrix former is superior to either of the individual polymers.Keywords: Domperidone, Extended drug release, Hydroxypropyl methylcellulose, Raphia hookeri gum, Tablet properties


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Emmanuel O. Olorunsola ◽  
Grace A. Akpan ◽  
Michael U. Adikwu

This study was aimed at evaluating chitosan-microcrystalline cellulose blends as direct compression excipients. Crab shell chitosan, α-lactose monohydrate, and microcrystalline cellulose powders were characterized. Blends of the microcrystalline cellulose and chitosan in ratios 9 : 1, 4 : 1, 2 : 1, and 1 : 1 as direct compression excipients were made to constitute 60% of metronidazole tablets. Similar tablets containing blends of the microcrystalline cellulose and α-lactose monohydrate as well as those containing pure microcrystalline cellulose were also produced. The compact density, tensile strength, porosity, disintegration time, and dissolution rate of tablets were determined. Chitosan had higher moisture content (7.66%) and higher moisture sorption capacity (1.33%) compared to microcrystalline cellulose and lactose. It also showed better flow properties (Carr’s index of 18.9% and Hausner’s ratio of 1.23). Compact density of tablets increased but tensile strength decreased with increase in the proportion of chitosan in the binary mixtures. In contrast to lactose, the disintegration time increased and the dissolution rate decreased with increase in the proportion of chitosan. This study has shown that chitosan promotes flowability of powder mix and rapid disintegration of tablet. However, incorporation of equal proportions of microcrystalline cellulose and chitosan leads to production of extended-release tablet. Therefore, chitosan promotes tablet disintegration at low concentration and enables extended-release at higher concentration.


Author(s):  
S. Fujishiro

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.


Author(s):  
G. Fourlaris ◽  
T. Gladman

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.


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