Binder Particle Size Research Articles

A study of the mechanical properties of coated papers using elastica stiffness and low-load indentation

Mechanical properties of coated papers, and specifically of a coating layer, are important during printing and converting operations. Those properties can be associated with several paper defects, such as coating pick, cracking at the fold, and dusting at the slitter. We introduced two dynamic tests for quantifying coating dynamic mechanical properties: (1) a closed loop elastica test and (2) a low-load indenter test. To evaluate these tests, several coatings on lightweight coated paper were produced with varying compositions and made under variable laboratory processing parameters. Pigment type, starch level, binder glass transition temperature, binder particle size, binder level, and drying method were varied. The moduli of a coating layer were extracted from elastica stiffness using a two-layer model. The shape factor of kaolin coating pigments had a significant effect; large shape factor led to increasing in-plane moduli but decreased elastic moduli measured in compression. The level of starch addition proportionally imparted stiffness. Laboratory drying conditions and styrene-butadiene latex type had a small effect.

The effect of the binder size and viscosity on agglomerate growth in fluidised hot melt granulation

Fluidised hot melt granulation (FHMG) is a novel granulation technique for processing pharmaceutical powders. Several process and formulation parameters have been shown to significantly influence granulation characteristics within FHMG. In this study we have investigated the effect of the binder properties (binder particle size and binder viscosity) on agglomerate growth mechanisms within FHMG. Low-melting point co-polymers of polyoxyethylene–polyoxypropylene (Lutrol ® F68 Poloxamer 188 and Lutrol ® F127 Poloxamer 407) were used as meltable binders for FHMG, while standard ballotini beads were used as model fillers for this process. Standard sieve analysis was used to determine the size distribution of granules whereas we utilised fluorescence microscopy to investigate the distribution of binder within granules. This provided further insight into the growth mechanisms during FHMG. Binder particle size and viscosity were found to affect the onset time of granulation. Agglomerate growth achieved equilibrium within short time-scales and was shown to proceed by two competing processes, breakage of formed granules and re-agglomeration of fractured granules. Breakage was affected by the initial material properties (binder size and viscosity). When using binder with a small particle size (<250 μm), agglomerate growth via a distribution mechanism dominated. Increasing the binder particle size shifted the granulation mechanism such that agglomerates were formed predominantly via immersion. A critical ratio between binder diameter and filler has been calculated and this value may be useful for predicting or controlling granulation growth processes.

Preparation of sustained release matrix pellets by melt agglomeration in the fluidized bed: Influence of formulation variables and modelling of agglomerate growth

The one-step preparation of sustained release matrix pellets, using a melting procedure in a fluidized bed apparatus, was tested in a 2 3 full factorial design of experiments, using microcrystalline wax as lipophilic binder, theophylline as model drug and talc as additional matrix forming agent. The three influence parameters were (A) size of binder particles, (B) fraction of theophylline in solid particles and (C) fraction of microcrystalline wax in formulation. The response variables were agglomerate size and size distribution, dissolution time, agglomerate crush resistance, sphericity, yield and porosity. Nearly spherical pellets comprising a smooth, closed surface could be obtained with the used method, exhibiting the hollow core typical for the immersion and layering mechanism. The reproducibility was very good concerning all responses. The size of agglomerates is proportional to the size of the binder particles, which serve as cores for pellet formation in the molten state in the fluidized bed. Additionally, the agglomerate size is influenced by the volume of the solid particles in relation to the binder particles, with more solid particles leading to larger agglomerates and vice versa. Dissolution times vary in a very wide range, resulting from the interplay between amount of drug in relation to the meltable matrix substance microcrystalline wax and the non-meltable matrix substance talc. The change of binder particle size does not lead to a structural change of the matrix; both dissolution times and porosity are not significantly altered. Agglomerate crush resistance is low due to the hollow core of the pellets. However, it is significantly increased if the volume fraction of microcrystalline wax in the matrix is high, which means that the matrix is mechanically better stabilized. A theoretical model has been established to quantitatively explain agglomerate growth and very good accordance of the full particle size distributions between predicted and actual values could be shown. A low volumetric binder to solids ratio is compensated by a more porous layer. On the basis of this model, in-depth understanding on the mechanism and influence of product properties could be gained; and an a priori estimation of particle size distributions for new formulas can be performed, with densities, formula, and binder particle size distribution as input parameters.

Formulation design for optimal high-shear wet granulation using on-line torque measurements

An alternative procedure for achieving formulation design in a high-shear wet granulation process has been developed. Particularly, a new formulation map has been proposed which describes the onset of a significant granule growth as a function of the formulation variables (diluent, dry and liquid binder). Granule growth has been monitored using on-line impeller torque and evaluated as changes in granule particle size distribution with respect to the dry formulation. It is shown how the onset of granule growth is denoted by an abrupt increase in the torque value requires the amount of binder liquid added to be greater than a certain threshold that is identified here as ‘minimum liquid volume’. This minimum liquid volume is determined as a function of dry binder type, amount, hygroscopicity and particle size distribution of diluent. It is also demonstrated how this formulation map can be constructed from independent measurements of binder glass transition temperatures using a static humidity conditioning system.

Cell Performance of the Membrane Electrode Assembly Based on Sulfonated-FEP/Nafion Blended Polymer

The sulfonated poly (tetrafluoroethylene-co-hexafluoropropylene) (s-FEP) membranes were synthesized by electron beam (EB) induced grafting method and then milled to the powder. The s-FEP/Nafion® blended dispersion (fn) was prepared by mixing s-FEP powder with the Nafion® dispersion. The s-FEP/Nafion® blended membrane (FN) was obtained by casting the fn binder into the membrane. The membrane electrode assemblies (MEAs) were fabricated by using the proton exchange membranes (FN or Nafion® 112) and the Pt/C electrodes coated with the binders (fn or Nafion® dispersion) . The fuel cell performances of the MEAs were examined. The maximum power density of the MEA using FN membrane and fn binder (particle size of s-FEP: 48 ± 17 μm) was about 600 mW cm-2. This was higher performance than any other tested MEAs. It is considered that this is because the compatibility at the membrane-binder interfaces is improved and the thermophysical properties of the PEM and the binder are essentially the same due to basically the same material.

Formation of hollow core granules by fluid bed in situ melt granulation: Modelling and experiments

Granules with a characteristic core–shell internal structure have been formed by in situ melt fluid-bed granulation, using d-mannitol primary solid particles and poly-ethylene glycol (PEG-6000) binder. The effect of binder particle size and binder/solids ratio on granule size distribution was systematically investigated. The mean granule size was found to be directly proportional to the binder particle size. The binder amount did not measurably affect the granule size, only the fraction of un-granulated fines. The microstructure of the granules was analysed by X-ray micro-tomography; the average shell thickness in the granules was found to depend on the binder/solids ratio, and the core volume was found to be directly proportional to the binder particle size. However, for binder particle size below a certain value the core–shell structure disappeared. A mathematical model based on a layering growth mechanism has been proposed and found to be consistent with experimental data. The proposed growth mechanism was confirmed by creating granules with bi-modal size distribution using a mixture of differently sized binder seeds.

The effect of binder particle size on granule and tablet properties in high shear and extrusion granulation

We investigated the effects of binder particle size on high shear and extrusion granulation using the wet granulation method by evaluating the properties of granules and tablets. Ethenzamide was used as a model drug at a concentration of 1% with lactose/corn starch in a 7/3 mixture, with 3.5% hydroxypropylcellulose and 0.5% magnesiuu stearate as the standard formulation, as recommended by the Standard Formulation Research Association. Hydroxypropylcellulose, as the binder, was classified into three particle size grades with the sieving method and used by the powder and solution addition method. In conclusion, although an effect of differences in the binder particle size on the particle size and its distribution in high shear granulation granules was observed, it was not an important parameter in the product properties. Accordingly, it was thought that standardization of the binder particle size was useful to control the granule particle size.

Agglomerate formation and growth mechanisms during melt agglomeration in a rotary processor

The purpose of this study was to investigate the effect of the binder particle size and the binder addition method on the mechanisms of agglomerate formation and growth during melt agglomeration in a laboratory scale rotary processor. Lactose monohydrate was agglomerated with molten polyethylene glycol (PEG) 3000 by adding the PEG either as solid particles from the size fraction 0–250, 250–500, or 500–750 μm or as droplets with a median size of 25, 48, or 69 μm. It was found that the PEG particle size, the PEG droplet size, and the massing time significantly influenced the agglomerate size and size distribution. Agglomerate formation and growth were found to occur primarily by distribution and coalescence for the PEG size fraction 0–250 μm and mainly by the immersion mechanism for the PEG size fractions 250–500 and 500–750 μm. When the PEG was sprayed upon the lactose, the mechanism of agglomerate formation was supposed to be a mixture of immersion and distribution, and the agglomerate growth was found to occur by coalescence regardless of the PEG mean droplet size. Compared to high shear mixers and conventional fluid bed granulators, the mechanisms of agglomerate formation and growth in the rotary processor resembled mostly those seen in the fluid bed granulator.

Growth mechanisms in melt agglomeration in high shear mixers

This paper presents a review of factors affecting the agglomerate formation and growth mechanisms in melt agglomeration in high shear mixers. The agglomerate formation occurs either by distribution or immersion or by a combination of both mechanisms. Distribution is promoted by a low binder viscosity, by a high impeller speed, and by a small binder particle size. Effects of the liquid saturation of the agglomerates, impeller speed, particle properties, binder viscosity, and electrostatic charging on the subsequent agglomerate growth are discussed, and experimental results are presented. The agglomerate growth becomes controlled by the balance between the agglomerate strength and the shearing forces. If the agglomerate strength is sufficiently high to resist the shearing forces of the rotating impeller, the dominant agglomerate growth mechanism will be coalescence. The shearing forces will give rise to breakage if the agglomerate strength is too low, and then agglomerate growth will occur by a simultaneous buildup and breakdown of agglomerates, possibly combined with growth by layering of fragments upon larger agglomerates. Provided that the liquid saturation is sufficiently high, a higher agglomerate strength is primarily caused by a higher binder viscosity, a smaller particle size, an irregular particle shape, and by densification of the agglomerates.

Direct evidence of heterogeneity during high-shear granulation

Despite the volume of research concerning granulation, the knowledge of its rate behaviour is still a matter of some debate. Here, granulation is explored by looking at the interaction between granule properties and rate behaviour; process conditions are perturbed to induce different rate behaviour. Granules of calcium carbonate powder (mass-mean size of approximately 40 μm) and Polyethylene Glycol (PEG) 1500 are made in a 10-l vertical axis, high-shear mixer with the PEG added in two different ways: by pouring on and melting in. The resulting granules are cooled and sieved on a fourth-root-of-two progression of sieves to obtain the granule size distribution. Granules in specific size ranges are analysed using a thermo-gravimetric technique, mercury porosimetry and the primary particles are liberated from the binder in order that their size distribution may be examined using a light-scattering particle size analyser. The results show marked differences between the two methods of binder addition. The granules made by pouring on the binder exhibit bimodal weight distributions that are unimodal by the end of the experiment, larger granules, faster growth, low air incorporation into granules and uniform binder and primary particle size distribution (PSD) by the end of an experiment. The granules made by melting the binder in situ exhibit bimodal weight distributions throughout an experiment, smaller granules, slower growth, higher incorporation of air into granules and nonuniform binder and primary PSD throughout. Both methods of binder addition show considerable heterogeneity in the properties of granules. We interpret the heterogeneity of binder distribution by means of the nucleation theories of Schaefer and Mathiesen [T. Schaefer, C. Mathiesen, Int. J. Pharm., 139 (1996) 139] concluding that pour-on experiments follow the Schaefer and Mathiesen Immersion Hypothesis and that melt-in experiments follow the Schaefer and Mathiesen Dispersion Hypothesis. We put forward two competing hypotheses for the heterogeneity found in the distribution of primary particle sizes: the Preferential Nucleation Hypothesis and the Preferential Growth Hypothesis. We believe that the former applies to pour-on experiments and the latter to melt-in experiments.

Influence of production variables on the sphericity of melt pellets.

This paper reports the influence of post-melt impeller speed, post-melt processing time, binder concentration and particle size of bulk material on the sphericity of pellets produced by melt pelletization in a high shear mixer. Lactose was used as the bulk material with polyethylene glycol 3000 as a meltable binder. The sphericity of pellets was found to be affected by post-melt impeller speed and post-melt processing time. Binder concentration and particle size of bulk material had a lesser effect on pellet sphericity. The melt pelletization process can be divided into two spheronization phases (a fast initial rate, followed by a slower rate). The change in the spheronization rate was associated with the pellet size, porosity and flow pattern of the processing material. The present study established a bi-exponential mathematical model to relate the pellet sphericity with post-melt specific energy consumption. The relationship of pellet sphericity with post-melt specific energy consumption was independent of the effects of the production variables.

Effects of Physical Properties of PEG 6000 on Pellets Produced by Melt Pelletization

This study examined the effects of polyethylene glycol (PEG) binders of different physical forms and from different commercial sources on size and size distribution of pellets produced. The meltable binders used were PEG 6000 in the form of flakes, and coarse and fine powders, and melt pelletization using lactose 450 M was carried out in an 8-liter high-shear mixer. Binder particle size, molecular weight, tack, and viscosity were determined. The results showed that the size and size distribution of the pellets obtained could not be explained by the binder particle size. The size and size distribution of the pellets were related to the tack and viscosity of the molten binders. PEGs used were labeled as the same nominal molecular weight grade, although their determined molecular weights could be quite different. Differences in tack and viscosity of the molten binders were associated with determined molecular weight of the binders. The melt pelletization process is sensitive to tack and viscosity of the molten binders. When different PEG brands of the same nominal molecular weight or different batches of the same brand are used in melt pelletization, it is important to characterize the tack and viscosity of the binders used. The effects of the physical form of binders on the pellet quality appear to be less important when compared to the influences of tack and viscosity of the molten binder.

Melt pelletization in a high shear mixer. IX. Effects of binder particle size

Lactose monohydrate was melt pelletized in an 8-1 high shear mixer. The meltable binders were polyethylene glycol (PEG) 3000, 6000, and 8000 used as flakes, coarse powder, and fine powder, and PEG 10000 and 20000 used as flakes and coarse powder. The distribution of the binder in different granule size fractions was dependent on the binder particle size. The binder particle size was reflected in the initial granule size at high binder viscosities. The fine powders gave rise to the lowest agglomerate growth rate, whereas a difference in growth rate between the flakes and the coarse powders was seen only at the highest viscosities.

Effects of binder content and particle size on green strength of wet powder poured parts: R. Vassen et al. (Forschungzentrum Jlich GmbH, Jlich, Germany.) Powder Metallurgy, vol 38, no 1, 1995, 55–58

Effects of binder content and particle size on green strength of wet powder poured parts: R. Vassen et al. (Forschungzentrum Jlich GmbH, Jlich, Germany.) Powder Metallurgy, vol 38, no 1, 1995, 55–58

Influence of Binder Content and Particle Size on Green Strength of WPP Parts

AbstractWet powder pouring (WPP) was developed as an alternative near net shape process to metal injection moulding (MIM). The amount of binder, which is necessary to obtain a sufficient green strength, is relatively low (2–5 vol.-%) compared to the amount used in the MIM process (about 30 vol.-%). This is advantageous with respect to short debinding times and low residual carbon and oxygen contaminations. A further reduction of the binder content or the application of the WPP process to new materials would be promoted by an understanding of the dependence of green strength on particle characteristics and binder content. In the present investigation the green strengths of stainless steel WPP parts were determined for different particle size distributions and different binder contents (2–8 vol.-%). The green strength was in the range 3 to 7 MN m−2 and the fracture mode was always brittle. A simple fracture mechanical model was developed, which was able to explain the observed relations between binder conte...

VARIOUS FACTORS INFLUENCING ABALONES GATHERING TO THE SHELTERS

This paper describes various factors influencing abalones gathering to the shelters. The experiments were carried out in the laboratory by using abalones and shelters which were produced through mixing fillers with many kinds of binders respectively. Following conclusions were obtained. 1) Abalone prefered the shelter with abalone mucus to the cleaned shelter. 2) Gathering rate of abalone to the shelter did not depend on the binder characteristics and particle size of ferrite by-products. 3) The higher content of ferrite by-products and the higher density of shelters, the more abalones were drawn into the shelters. 4) The abalones did not cling to small size of gravels.

Removal of low density lipoprotein from blood plasma using cross-linked, sulfated polyvinylalcohol

The properties of a new synthetic LDL binding material, consisting of fragments of loosely crosslinked hydrogel, based on sulfated polyvinylalcohol are described. When incubated with 20 times its volume of plasma, this material binds up to 95% of the LDL, even from plasma with severely elevated LDL cholesterol levels (up to 20 mM). In addition a cholesterol-rich subfraction of VLDL is bound but HDL is not bound. After about 10 min binder/plasma contact the LDL removal is complete and no other additives are required. LDL binding capacity is dependent on the average binder particle size, indicating a restricted penetration of LDL particles into the binder matrix.

Studies on direct compression of tablets. XIII. The effect of some dry binders on the tablet strength of compounds with different fragmentation propensity

Both fine and coarse fractions of Avicel PH 101, Avicel PH 105, methyl cellulose and polyvinylpyrrolidone were added to compounds with poor binding properties. The binding effect differed only slightly between the three binders tested, whereas a decrease in binder particle size effectively improved tablet strength. The effect of the binder additions was strongly dependent upon the fragmentation propensity of the compounds. The technique to cover the compounds with a fine binder resulted in stronger tablet for the compounds, which were less prone to fragment during compaction.

Refractory metal carbide coatings for LMFBR applications—A systems approach

Selection of existing coatings or the design of new coatings for wear resistance in sodium-cooled nuclear reactors, particularly applications for core components, requires consideration of numerous unique criteria associated with this class of reactors. Wear resistance, low friction characteristics, and long-term, high-temperature chemical compatibility with the coolant and with the substrate are among the major concerns. Thermal transients in this high-temperature environment necessitate coatings with adequate thermal shock resistance. High neutron fluences require materials that are stable under irradiation and which do not transmute to undesirable elements. The selection, testing, and improvement of high-density, tightly bonded plasma and detonation- gun coatings designed to meet all of these criteria are described. The process descriptions include a review of the important developments in substrate surface preparation which are required to ensure strong bonding and to minimize interface contamination. Coating finishing techniques which were developed to optimize friction behavior are also described. The need for low-friction behavior has been an important requirement in the design of the coatings. Chromium-carbide coatings with a Ni–Cr binder applied with a detonation gun have been shown to possess acceptable friction, wear, and corrosion properties. Further enhancement of these properties was made through modification of the metallic binder particle size and the cabide–binder ratio. The use of Inconel 718, Mo, and Tribaboy 700 binders were evaluated in an effort to improve the friction and self-welding characteristics as well as to improve the corrosion resistance in liquid Na.