Influence of the Cutting Edge Angle of the Granulator on the Extrusion Process and Pellets Properties (original) (raw)
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International Journal of Pharmaceutics, 1993
Preliminary studies with an instrumented, co-rotating twin-screw extruder were performed. The variation of water content of the extruded mass is dependent on the accuracy of both dry powder and granulation liquid feed rate. Using a given powder feed rate it is easy to vary the water content by changing the liquid feed rate. Operating the twin-screw extruder in this way the extrudcr barrel is not completely filled with wet mass. The steady state mass is dependent on both screw speed and mass flow rate. This leads to different behaviour of extrusion process variables compared to extruders with completely filled barrels. With a central composite design the influence of screw speed and water content on passage time, steady state mass and the process variables corrected power consumption, pressure and end temperature of extrudate were studied. Water content is the most important variable for the extrusion process variables. For further studies it is strictly recommended either to control the water content or to use it as a variable.
Comparison of two twin-screw extruders for continuous granulation
European Journal of Pharmaceutics and Biopharmaceutics, 2009
A comparison was made between two twin-screw extruders (APV Baker and Leistritz Micro) used for continuous wet granulation. Both extruders had similar screw configurations, based on the length-to-diameter ratio of the screws, existing out of a conveying zone of 20 D, i.e. 20 times the screw diameter and a granulation zone of 4 D. The kneading blocks in the granulation zone were 2.2 and 2.5 D for the Leistritz and APV extruders, respectively. An experimental design was used to investigate the influence of process parameters (total input rate and screw speed) and extruder type on granule and tablet quality. Dicalcium phosphate and a-lactose monohydrate were used as water-insoluble and water-soluble excipients, respectively. For dicalcium phosphate, the amount of fines (<125 lm), median granule size and granule friability were significantly influenced by extruder type and total input rate. For lactose, the amount of oversized agglomerates and median granule size were significantly affected by extruder type and total input rate. The granule formulations were properly agglomerated on both the extruders, although the extruder type had an important influence on the granule properties, which was more pronounced for dicalcium phosphate. This study shows that a given formulation cannot simply be interchanged between the two extruders without further work on the geometrics of the extruders.
Aaps Pharmscitech, 2021
In order to be at pace with the market requirements of solid dosage forms and regulatory standards, a transformation towards systematic processing using continuous manufacturing (CM) and automated model-based control is being thought through for its fundamental advantages over conventional batch manufacturing. CM eliminates the key gaps through the integration of various processes while preserving quality attributes via the use of process analytical technology (PAT). The twin screw extruder (TSE) is one such equipment adopted by the pharmaceutical industry as a substitute for the traditional batch granulation process. Various types of granulation techniques using twin screw extrusion technology have been explored in the article. Furthermore, individual components of a TSE and their conjugation with PAT tools and the advancements and applications in the field of nutraceuticals and nanotechnology have also been discussed. Thus, the future of granulation lies on the shoulders of continuous TSE, where it can be coupled with computational mathematical studies to mitigate its complications.
Cold extrusion as a continuous single-step granulation and tabletting process
European Journal of Pharmaceutics and Biopharmaceutics, 2001
The potential of cold extrusion as a continuous granulation/tabletting technique was investigated. Extrudates (B, 9 mm) were produced using twin-screw extrusion, cut manually into tablets (thickness, 4 mm) and dried at 258C for 20 h. a-Lactose monohydrate (200 M) was used as an excipient, PVP (Kollidon w K30) and water as binders, and hydrochlorothiazide as the model drug. The influence of formulation (water content, PVP addition, drug incorporation) and process (total input rate and screw speed) parameters on the process (torque, die pressure, visual evaluation of tablets) and on the tablet properties (tensile strength, friability, disintegration time, porosity) was evaluated. Formulation, as well as process parameters, affected the process feasibility, but had only a minor effect on the tablet properties at conditions that allowed continuous tablet production. All a-lactose monohydrate tablets formulated without and with PVP and produced at optimum conditions showed tensile strengths above 0.7 and 1.5 MPa, friabilities below 1.0 and 0.9%, and disintegration times below 1 and 8 min, respectively. This technique allows single-step granulation/tabletting of pure a-lactose monohydrate, indicating that cold extrusion could be used as alternative tablet production technique for ingredients with poor compaction properties. As the tablets prepared by extrusion have a much higher porosity compared with conventional tablets, this technique could also be useful for tablet production of formulations with poor disintegrating properties. q
A novel design for hot-melt extrusion pelletizers
Chemical Engineering Science, 2010
In this work we investigated a novel die design for the scale-up of hot melt extrusion (HME) devices for direct pelletization of pharmaceutics. Therefore we analyzed the temperature distribution in a lab-and production-scale die as well as melt flow through the die. Finally we explored the possibilities of an inner rotating knife for stabilizing melt flow. The work was based on computational fluid dynamics for simulating non-Newtonian melt flow and corresponding temperature fields.
Experimental and theoretical study on polymer extrusion
2018
El trabajo consta de un análisis experimental y teórico en el proceso de extrusión polimérica para estudiar el efecto de los parámetros de extrusión, las propiedades del material, los parámetros geométricos y las condiciones de operación
Methods of Pelletization Using Extrusion – Spheronization: A Review
International Journal of Pharmacy and Pharmaceutical Research
Nowadays, multiple unit dosage forms (MUDF) are preferred as they offer many benefits over a single unit dosage form. The extrusion-spheronization technique is the most widely used technique for the production of MUDF. This article deals with multiple aspects and parts of the extrusion-spheronization techniques. The initial part deals with different steps in the manufacturing of pellets such as granulation, extrusion, spheronization, and drying while the final part deals with the parameters that govern the quality of pellets. Wherein formulation aspects like moisture content, granulating liquid, excipients and API, equipment aspects like a mixer, extruder, friction plate, and extrusion screen and process aspects like extrusion temperature, extrusion speed, spheronization time, spheronizer load, spheronization speed, and drying, etc. This review also summarizes the pallets characterization aspects like particle size distribution, surface area, and surface roughness, tensile strength, angle of repose, scanning electron microscopy, accelerated stability study properties, etc.
Thermal and mechanical degradation during polymer extrusion processing
Polymer Engineering & Science, 2007
Polymer processing often activates material degradation, which affects to some extent the performance or the life cycle of the obtained products. Polymer degradation is usually evidenced by molecular weight variations as consequence of exposure to high processing temperature and to relevant mechanical stresses. The degrading effects of melt extrusion under different thermo-mechanical conditions on polymethyl-methacrylate and polystyrene are investigated. Materials were processed at different temperatures and rates in a single screw extruder and in a capillary rheometer. Processed and as-received materials were analysed by Gel permeation chromatography, solution viscosity, and melt rheology. Evaluations of molecular weight and rheological behavior changes after processing, as compared with as-received materials, evidenced the extent of degradation in the different conditions. Experimental analysis was accompanied by finite elements simulation of the polymer flow and heat transmission within the extruder. This allowed an estimation of the expected shear stresses and temperatures distributions, thus indicating potentially critical situations. It was found that the materials processed at the highest rates in extruder presented lowest molecular weight reductions. This was attributed to the shorter residence time in the extruder and to the possibility of wall slip phenomena, which likely reduce the actual shear stress and viscous dissipation in the fast processing conditions.
AN OUTLINE OF VARIABLES IN PELLETIZATION BY EXTRUSION AND SPHERONIZATION Review Article
International Journal of Applied Pharmaceutics, 2020
Pelletization is an agglomeration process which converts fine granules or powders of bulk drugs into small, free-flowing, spherical units, known as pellets. The pelletization can be achieved either through agitation, compaction (extrusion-spheronization), drug layering and globulation. Among the various pelletization techniques extrusion-spheronization process is preferred over other methods for the preparation of pellets as it allows the incorporation of the higher amount of drug, modified physical characteristics of the drug (density, sphericity, narrow size distribution, smoother surface) and multiple drugs can be easily combined in the same unit. This current review summarizes the findings or investigations by the researchers on various variables, including process parameters, equipment parameters and formulation parameters influencing the quality of pellets. The article also focuses on process optimization and additives used in pellets formulation. To prepare the current review search criterion used was the parameters affecting final pellet characterization in the extrusion spheronization process. The sources were peer-reviewed relevant scientific articles of recognized journals. Keywords used as filters were extrusion, spheronization, formulation parameters, process parameters, equipment parameters, moisture content, granulating liquid, drying rate, extrusion temperature, spheronizer load, pelletization. Literature survey has been done in a range of years (1992-2019) regarding the various variables of the extrusion spheronization process, which affects and has foremost impact on the final quality of pellets so as to make the review updated and comprehensive.
The planetary roller extruder is well known for its superior mixing performance and its exact temperature control capabilities. Therefore it is widely used in the polymer industry for the compounding of shear-and temperature sensitive materials like PVC or Wood Plastic Composites. In contrast to the considerable amount of scientific work that deals with investigation, modeling or simulation of the process behavior of single and twin screw extruders, there are only few publications about the planetary roller extruder. Due to increased quality requirements and the trend to cost reduction by process optimization, this is increasingly becoming a problem for plant construction and processing companies. In our former work first analysis of the plastics melting process in planetary roller extruders were conducted and models describing these processes were published. However the influences of pellet diameter or inorganic filler were not considered. As a consequence the process models are only valid for a partial amount of the materials processed on planetary roller extruder. This paper presents experimental melting behavior investigations of powder, micro pellets and standard pellets. Furthermore the influence of filler amount is examined with standard pellets. At these experiments the melting initiation and the melting propagation is determined. Based on the experimental results, a theoretical consideration for melting in planetary roller extruders is proposed.