Prediction of granule physical property by a novel compression energy of wet powder

Wet granulation is a very important process and a reliable evaluation method for formulation study; thus it requires appropriate process control. In this study, a novel and effective method that involves a compression test of wet powder is proposed. Here, the compression energy, which could predict the capability of the wet powder for extrusion granulation as well as the physical properties of the final products, is used as a novel characteristic of wet powder. The compression energy was defined as the energy consumption derived from the compression speed and the transmission loss during the compression test. Lactose monohydrate was mixed with various additives such as hydroxypropylcellulose in the mass ratio of 0-10%. Various amounts of water were fed into the mixtures, which were kneaded in a planetary motion mixer to prepare the kneaded wet powders. The characteristics of these powders were evaluated by the compression energy. The kneaded wet powders were then extruded through an extrusion granulator, the electrical loads of the granulator during the operation were analyzed as the extrusion energy, and the physical properties of extruded granules were investigated. As a result, the granule strength and granule size distribution showed a good correlation with the compression energy. A good correlation was also observed between the compression energy of the kneaded wet powder and the extrusion energy regardless of the different additives and water contents. It was concluded that the compression energy of the wet powder could be used for the formulation study and the process control of wet granulation.     

Development of a novel compression tester and rheo-mechanical properties of wet-mass powder. I--Effect of kneading time on the rheo-mechanical properties

In our previous paper [Watano S., et al., Chem. Phram. Bull., 49(1), 64-68, (2001)], a compaction tester was developed to quantitatively evaluate the water dispersion condition of wet kneaded masses prepared by a paddle type kneader. It was also demonstrated that the physical properties of pellets prepared by extrusion granulation after the kneading could be well predicted by the vertical pressure transmission obtained through the compaction tester. However, in this compression tester, the vertical pressure transmission was just obtained and rheological and mechanical properties (so called rheo-mechanical properties) of wet mass-powder that should be the most important to determine the deformation process were not well studied. In this study, a novel compression tester, which can measure both vertical and radial pressure transmissions, has been developed. Based on the compression test, mechanical property (Young's modulus) and rheological property (effective internal friction) of wet mass powder prepared by different kneading times were quantitatively investigated. Granules (pellets) were then obtained through the extrusion granulation and fluidized bed drying, and the physical properties (strength and disintegration time) of the obtained pellet were evaluated. The relationship between the granule (pellet) physical properties and the mechanical and rheological (rheo-mechanical) properties was analyzed.     

Development of a novel vertical high shear kneader and its performance in wet kneading of pharmaceutical powders

A novel multi-functional vertical high shear kneader has been developed. Wet kneading of pharmaceutical powders was conducted under various blade components and operating conditions. Compression properties of wet kneaded mass was analyzed and dispersion of hinder liquid (water) among the mass was investigated by assaying tracer aqueous pigment. Pellets were produced through a dome type extrusion granulator with continuous extrusion pressure measurement device and a fluidized bed drier, and then the physical properties were measured. Quantitative relationship between the pellet's physical properties and the binder dispersion condition as well as the compression properties could be obtained. It was found that the newly developed kneader was very effective to uniformly disperse binder as well as impart high shear stress to the wet mass without generating obvious adhesion onto the vessel wall. It was also pointed out that the extrusion pressure could determine the physical strength of pellet. This method proposes a new methodology for continuous monitoring of kneading condition as well as predicting pellet's physical properties.     

Scale-up of wet kneading in a novel vertical high shear kneader

A novel multi-functional vertical high shear kneader has been developed and its performance in wet kneading has previously been reported [Watano et al., Chem. Pharm. Bull., 50(3), 341-345 (2002)]. In this study, scale-up of wet kneading in the novel vertical high shear kneader was conducted. Pharmaceutical excipients composed of lactose, cornstarch and micro-crystalline cellulose were used as powder samples. Kneading operations were conducted under various operating conditions and three different vessel scales. The dried pellets were then prepared by extruding the wet kneaded masses through a dome-type extruder and their drying by a fluidized bed. The physical properties such as strength and disintegration time of the dried pellets were evaluated. It was found that the properties of the dried pellets and their scale-up characteristics were well expressed by an agitation power per unit vessel volume and dimensionless Froude number.     

Quantitative analysis of water dispersion conditions and pressure transmission characteristics of a wet kneaded mass

In our previous paper [Watano S. et al., J. Powder Technology Japan, 37, 362-370 (2000)], a novel compaction tester was developed to quantitatively evaluate the water dispersion condition of a wet kneaded mass prepared by a paddle type kneader. It has been demonstrated that the physical properties of pellets prepared by extrusion granulation after the kneading can be well predicted by the pressure transmission obtained through the compaction tester. This paper describes a more detailed investigation of the water dispersion, its mechanism and pressure transmission characteristics of wet kneaded masses prepared under various operating conditions. First, kneading by a paddle type kneader was conducted to prepare wet masses under various binder contents using different additional methods and different starting materials. Secondly, water dispersion and pressure transmission characteristics of wet masses were investigated. After the wet kneading, the wet kneaded masses were extruded through a dome type extruder and were dried by a fluidized bed to prepare dry pellets. The relationship between water dispersion and pressure transmission can be expressed by a single line, regardless of binder content or methods of addition. This implies that these parameters have no effect on the water dispersion condition of the wet kneaded mass prepared by a high shear paddle type kneader. Different water dispersion characteristics and the mechanism obtained by different starting materials can also be evaluated by the pressure transmission data. Properties of dry pellets can also be predicted by the pressure transmission. It can be concluded that the developed compaction tester can quantitatively evaluate the water dispersion condition of a wet kneaded mass and also predict properties of the final extruded products.     

Effects of recycling on mechanical and thermal properties of polystyrene

A commercial Polystyrene (M_w = 2.5 10⁵, MFI =14.80) was extruded repeatedly from one to eight times at 190 °C. The effects of extrusion process on physical and chemical properties of polystyrene were investigated using: -Average molecular weight

• —Izod Impact strength;
• —Thermal properties (TGA, DTA).

The results showed that processing of polystyrene leads to degradation. In fact, a decrease of 23% in the average molecular weight was observed for the 8^th cycle sample and a reduction in impact strength by 34% was also noticed for the 4^th cycle sample.     

Scale-up of high shear granulation based on the internal stress measurement

Scale-up of wet granulation in a vertical high shear mixer was conducted. Pharmaceutical excipient powders composed of lactose, cornstarch and micro-crystallinecellulose, and hydroxypropylcellulose as a binder were mixed together and then granulated with purified water under various operating conditions and vessel scales. A novel internal stress measurement system was developed and stress of normal and tangential directions that granules received from the agitator blade during the granulation was continuously measured. The results indicated that granules received stress mainly from the tangential direction, which also showed the largest value near at the vessel wall. The effects of the agitator tip speed and the centrifugal acceleration on the measured stress was investigated. It was found that the tip speed of the agitator blade could be the main factor for the granule growth. The physical properties such as strength, size distribution and compressibility of granules prepared by changing the operating conditions and the vessel scales were evaluated and the scale-up characteristics of high shear granulation were investigated experimentally. The results showed that these physical properties had linear correlations with the tip speed. It was finally concluded that the scale-up of high shear granulation could be well conducted by means of the tip speed of the agitator blade.     

Extrusion Cooking Effect on Carbohydrate Fraction in Novel Gluten-Free Flours Based on Chickpea and Rice

Extrusion cooking allows the development of value-added products from pulses, such as gluten-free snacks with added functional properties. The main objective of this study was to evaluate the changes induced by the extrusion process on the carbohydrate fraction (total carbohydrates, soluble sugars and oligosaccharides, dietary fiber, and arabinoxylans) of novel flour formulations based on chickpeas and rice enriched with different dietary fiber sources. Moreover, the influence of the addition of fiber-rich ingredients, such as Fibersol^® and passion fruit, on the analyzed compounds was also evaluated. Sucrose was the main soluble sugar found in analyzed formulations, and raffinose was the prevalent oligosaccharide, followed by stachyose. The content of total α-galactosides tended to be higher after extrusion cooking. As a consequence of the extrusion treatment, the content of total and soluble dietary fiber was statistically increased in most of the analyzed samples. In general, no significant changes were observed in total arabinoxylan content as a consequence of the extrusion process, while the content of water-soluble arabinoxylans was significantly increased in extruded formulations. It was observed that the content of total available carbohydrates, stachyose, and water-soluble arabinoxylans were significantly influenced by the addition of passion fruit, Fibersol^®, and both. The incorporation of these ingredients in gluten-free formulations based on chickpeas and rice allows one to obtain suitable functional formulations for the development of innovative, gluten-free, extruded snack-type products, which could be an interesting alternative for people with celiac disease.     

Influence of extrusion ratio on the tensile properties of ultradrawn polyethylene

The tensile properties have been evaluated for high-density solid-state polyethylene extruded to different extrusion (draw) ratios. The results are compared with measured and theoretical values on this and other polymers. An extrusion (draw) ratio and a deformation gradient are defined and discussed. The content of extended tie molecules in extruded high-density polyethylene was calculated from a model and modulus data.     

Rheological analysis and quantitative evaluation of wet kneaded wax matrix

The properties of the wet kneaded wax matrix were evaluated using a compression tester, whereby a newly proposed sigma index for the plastic deformation was assessed in the pressure transmission diagram. The sigma index was indicative of a characteristic of the plastic yield point in the rheological behavior, and presented an initial and abrupt deformation of wet kneaded mass when the wet kneaded mass was subjected to the pressure. The value of sigma index was confirmed to decrease along with an increase in the plasticity of wet kneaded mass. The wet mass of wax matrix was prepared under various kneading time, and then extruded. The properties of the extruded granules such as pore volume, strength and dissolution were investigated. As a result, it was found that the sigma index decreased with an increase in kneading time. The granules with small value of sigma index showed few porosities, large strength and slow dissolution. It was demonstrated that the sigma index linked the characteristics of wet kneaded mass to the dissolution and the other granule properties. Existence of this link was revealed by sigma index evaluation relevant to the plasticity. The sigma index could be a decisive criterion to permit an in-process evaluation of the kneading progress quantitatively, and also useful for anticipating the dissolution of the final granules roughly.     

Characteristics of solid-state extruded polyethylene

This paper describes the properties of solid-state extruded polyethylene as a function of two primary processing variables, extrusion temperature, and area reduction. The polymer was extruded in sheet form, giving a material having an orthotropic mode of orientation. Property data are presented for melting temperature and heat of fusion; sonic modulus, yield stress, and elongation at fracture; small-angle x-ray scattering; optical absorption coefficient; and morphology for material etched by ion bombardment at liquid nitrogen temperature. Combining the present results with data previously reported in the literature, it is found that over the temperature range of about 90–120°C, where polyethylene can be successfully extruded to large area reductions, many properties of the extrudates show a surprisingly small dependence on extrusion temperature. A notable exception to this behavior is the elastic modulus, which increases significantly with increasing extrusion temperatures. In contrast to extrusion temperature, area reduction is found to have a major effect on nearly all properties of solid-state extruded polyethylene. In most cases, the form of this dependence is such that the properties change rapidly at small area reductions and much more slowly at large reductions.     

反式异戊橡胶合金改性溶聚丁苯橡胶/顺丁橡胶轿车胎面胶

研究了反式异戊橡胶合金(TPIR)的结晶性能、加工性能和力学性能及在轿车胎面胶溶聚丁苯橡胶/顺丁橡胶(SSBR/BR)中的应用.研究结果表明,与无定形SSBR和BR相比,TPIR生胶具有常温可结晶性,因此TPIR具有较高的格林强度.毛细管挤出行为研究结果表明,TPIR具有优异的挤出性能,挤出物外观光滑,挤出涨大比小.与SSBR/BR混炼胶相比,用TPIR改性后的SSBR/BR/TPIR混炼胶的格林强度与100%定伸应力随TPIR含量的增加而提高.经150℃硫化反应后制备的SSBR/BR/TPIR硫化胶物理机械性能优异:不仅耐湿滑性能、耐磨耗性能及压缩强度较对比胶提高,其伸张疲劳性能较对比胶提高4倍以上.透射电子显微镜(TEM)及填料分散仪表征结果表明,与SSBR/BR硫化胶相比,SSBR/BR/TPIR硫化胶的填料聚集体平均尺寸降低2μm,填料分散性显著改善.表明TPIR是一种应用于高性能轿车胎面胶的理想胶料.     

混合方式对增容尼龙-6/聚苯醚体系的影响

研究了三种混合方式对于Nylon 6 PPO TPEg共混体系的影响 .混合是在双螺杆挤出机上进行的 .即(A)尼龙 6、聚苯醚和TPEg的混合物直接进行熔融挤出 ;(B)尼龙 6与TPEg的混合物预挤出 ,然后与聚苯醚熔融挤出 ;(C)聚苯醚和TPEg的混合物预挤出 ,然后与尼龙 6熔融挤出 .实验结果表明 ,混合方式不仅会影响共混物的形貌结构 ,而且会影响复合材料的最终性能 ,如力学性能、热性能和尺寸稳定性 .采用混合方式C所得的尼龙 6 聚苯醚复合材料的抗冲击强度高于用混合方式A和B所制备的复合材料 .这是因为聚苯醚和TPEg预共混时 ,聚苯醚上的OH基团和TPEg上的一部分马来酸酐发生化学反应 .然后预混物和尼龙 6熔融挤出时 ,剩下的马来酸酐再与尼龙分子上的NH2 基团反应 .这样就会形成一个好的界面层 ,它使复合材料的抗冲击强度大幅度提高 ,材料达到了超高韧性     

Thermal stability and degradation of the post-use reclaim milk pouches during multiple extrusion cycles

In the present study, the recyclability of the post-use milk pouches (50/50 LDPE–LLDPE blend) was evaluated with or without adding stabilizer. Thoroughly washed and dried post-use milk pouch films were extruded five times at high temperature (483–513 K) in the open atmosphere. The mode of degradation during extrusion operation was studied by melt flow index (MFI), rheological properties, gel content and FT-IR analysis. The differential scanning calorimetry (DSC) analysis was carried out to evaluate the thermal stability of the stabilized and un-stabilized recycled mass from post-use milk pouch under this investigation. Mechanical properties (tensile strength, % elongation at break, tensile modulus and hardness) of the un-stabilized extruded material were significantly affected as a result of thermooxidative degradation during extrusion in presence of air. After all, stabilization with 0.4% anti-oxidant satisfactorily retains all the initial properties of the recycled material.     

Biodegradable ultra high strength poly(L-lactide) rods for bone fixation

The hydrostatic molecular orientation technique was used to explore the highest mechanical improvements achievable for poly-L-lactide (PLLA). The mechanical attributes of these materials designed for bone fracture fixation devices, i.e. bending strength and modulus were measured and compared with those prepared by stretching method. The starting samples were prepared by conventional melt extrusion at 200 °C followed by hydrostatic extrusion at 140 °C using glycerin filled extruder. Uniaxially stretched rods were prepared by drawing in silicon oil at 120 °C. The physical properties of these rods are inadequate as mechanical supports in the dynamic healing process of the bone. Moreover, they underwent a marked strength deterioration when immersed in aqueous buffered solution for 90 days. On the other hand, the hydrostatic extrusion technique produced rods with progressively higher bending strength that showed only a small drop after 90 days hydrolytic degradation. Micrographs suggested a superior molecular orientation and packing, which could be associated with the improved performance. The hydrostatic extrusion technique proved to be a safe and effective approach for strengthening biodegradable polymeric materials for dynamic mechanical support in orthopedic medical devices.     

用反应挤出法制备尼龙6塑料

利用双螺杆挤出机进行了尼龙６阴离子开环聚合反应的研究，通过改变引发剂及活化剂的浓度、螺杆转速、机筒的温度分布以及螺杆元件构型的排布等，研究这些工艺参数对尼龙６反应挤出产物性能的影响。结果表明，反应挤出的尼龙６综合机械性能比水解缩聚法生产，且具有较高的性能价格比。     

Evaluation of grinding methods for pellets preparation aiming at the analysis of plant materials by laser induced breakdown spectrometry

It has been demonstrated that laser induced breakdown spectrometry (LIBS) can be used as an alternative method for the determination of macro (P, K, Ca, Mg) and micronutrients (B, Fe, Cu, Mn, Zn) in pellets of plant materials. However, information is required regarding the sample preparation for plant analysis by LIBS. In this work, methods involving cryogenic grinding and planetary ball milling were evaluated for leaves comminution before pellets preparation. The particle sizes were associated to chemical sample properties such as fiber and cellulose contents, as well as to pellets porosity and density. The pellets were ablated at 30 different sites by applying 25 laser pulses per site (Nd:YAG@1064 nm, 5 ns, 10 Hz, 25 J cm⁻²). The plasma emission collected by lenses was directed through an optical fiber towards a high resolution echelle spectrometer equipped with an ICCD. Delay time and integration time gate were fixed at 2.0 and 4.5 μs, respectively. Experiments carried out with pellets of sugarcane, orange tree and soy leaves showed a significant effect of the plant species for choosing the most appropriate grinding conditions. By using ball milling with agate materials, 20 min grinding for orange tree and soy, and 60 min for sugarcane leaves led to particle size distributions generally lower than 75 μm. Cryogenic grinding yielded similar particle size distributions after 10 min for orange tree, 20 min for soy and 30 min for sugarcane leaves. There was up to 50% emission signal enhancement on LIBS measurements for most elements by improving particle size distribution and consequently the pellet porosity.     

Understanding the Impacts of AFEX™ Pretreatment and Densification on the Fast Pyrolysis of Corn Stover,Prairie Cord Grass,and Switchgrass

Lignocellulosic feedstocks corn stover, prairie cord grass, and switchgrass were subjected to ammonia fiber expansion (AFEX?) pretreatment and densified using extrusion pelleting and ComPAKco densification technique. The effects of AFEX? pretreatment and densification were studied on the fast pyrolysis product yields. Feedstocks were milled in a hammer mill using three different screen sizes (2, 4, and 8 mm) and were subjected to AFEX? pretreatment. The untreated and AFEX?-pretreated feedstocks were moisture adjusted at three levels (5, 10, and 15 % wb) and were extruded using a lab-scale single screw extruder. The barrel temperature of the extruder was maintained at 75, 100, and 125 °C. Durability of the extruded pellets made from AFEX?-pretreated corn stover, prairie cord grass, and switchgrass varied from 94.5 to 99.2, 94.3 to 98.7, and 90.1 to 97.5 %, respectively. Results of the thermogravimetric analysis showed the decrease in the decomposition temperature of the all the feedstocks after AFEX? pretreatment indicating the increase in thermal stability. Loose and densified feedstocks were subjected to fast pyrolysis in a lab-scale reactor, and the yields (bio-oil and bio-char) were measured. Bio-char obtained from the AFEX?-pretreated feedstocks exhibited increased bulk and particle density compared to the untreated feedstocks. The properties of the bio-oil were statistically similar for the untreated, AFEX?-pretreated, and AFEX?-pretreated densified feedstocks. Based on the bio-char and bio-oil yields, the AFEX?-pretreated feedstocks and the densified AFEX?-pretreated feedstocks (pellets and PAKs) exhibited similar behavior. Hence, it can be concluded that densifying the AFEX?-pretreated feedstocks could be a viable option in the biomass-processing depots to reduce the transportation costs and the logistical impediments without affecting the product yields.     

Reconstruction of core-shell dispersed particles in impact polypropylene copolymer during extrusion

We reported an approach to reconstruct the complex phase morphology of impact polypropylene copolymer(IPC) with core-shell dispersed particles and to optimize its toughness in approximate shear condition. The molten-state annealing results indicate that the phase structure with core-shell dispersed particles is unstable and could be completely destroyed by static annealing, resulting in the degradation of impact strength. By using a co-rotating twin screw extruder, we found that the dispersed particle with core-shell structure could be rebuilt in appropriate condition with the recovery of excellent impact strength due to both the huge interfacial tension during solidification and the great difference in viscosity of components. Results reveal that almost all the extruded IPCs show the impact strength 60%-90% higher than that of annealed IPCs at room temperature. And the twice-extruded IPC shows the highest impact strength, 446% higher than that of IPC annealed for 30 min. As for low temperature tests, the impact strength of extruded IPCs also increases by 33%-58%. According to adjusting the processing conditions including extrusion speed, extrusion frequency and temperature, an optimization of toughness was well established.     

The effect of sodium alginate on physical and dissolution properties of Surelease-matrix pellets prepared by a novel pelletizer

The aim of this study was to investigate the effect of sodium alginate on the physical and dissolution properties of Surelease-matrix pellets prepared by a novel pelletizer-equipped piston extruder and double-arm counter-rotating rollers. The mean values of the shape factor (e(R)) and the aspect ratio of Surelease-matrix pellets were 0.615-0.625 and 1.06-1.070, respectively, indicating good sphericity of the pellets. The drug release rate increased as the amount of sodium alginate increased due to hydration, swelling, and erosion within the Surelease-matrix pellets. In addition, the porosity of pellets also increased with increasing sodium alginate content. The results of this study show that sodium alginate has a greater effect on the drug release rate than the drug release mechanism within the Surelease-matrix for sparingly water-soluble drug, such as tamsulosin hydrochloride.