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Yang M.,New Jersey Institute of Technology | Wang P.,New Jersey Institute of Technology | Huang C.-Y.,Wyeth Research | Ku M.S.,Wyeth Research | And 3 more authors.
International Journal of Pharmaceutics | Year: 2010

In this study, a model drug, acetaminophen (APAP), was melt mixed with poly(ethylene oxide) (PEO) using a Brabender mixer. APAP was found to recrystallize upon cooling to room temperature for all the drug loadings investigated. Higher drug loading leads to faster recrystallization rate. However, the morphology of the recrystallized drug crystals is identical in samples with different drug loadings and does not change with the storage time. To adjust the drug's dissolution rate, nanoclay Cloisite® 15A and 30B were added into the binary mixture. The presence of either of the nanoclay dramatically accelerates the drug's recrystallization rate and slows down the drug's releasing rate. The drop of the releasing rate is mainly due to the decrease of wettability, as supported by the contact angle data. Data analysis of the dissolution results suggests that the addition of nanoclays changes the drug's release mechanism from erosion dominant to diffusion dominant. This study suggests that nanoclays may be utilized to tailor the drug's releasing rate and to improve the dosage form's stability by dramatically shortening the lengthy recrystallization process. © 2010 Elsevier B.V.


Suwardie H.,Polymer Processing Institute | Wang P.,University of Rhode Island | Todd D.B.,Polymer Processing Institute | Panchal V.,U.S. Army | And 3 more authors.
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2011

There is a growing interest of extrusion drug and polymer together to manufacture various solid dosages. In those cases, the drug's release profiles are greatly affected by the miscibility of two materials. The goal of this study is to test the drug's solubility in molten polymer and obtain the mixture's rheological properties for the purpose of optimizing the extrusion process. The dynamic and steady viscosities of APAP-PEO mixture were determined using oscillatory and capillary rheometers. The curves of viscosity vs. drug loading generally have a "V" shape, and the minimal point gives the APAP's solubility in PEO. The test results suggest that different dynamic methods lead to essentially the same solubility data. At high shear rates, the mixtures show shear thinning behavior and the viscosity becomes less sensitive to the drug loading. In other words, it is desirable to use a low shear rate in order to deduce the drug's solubility in polymer from the viscosity data. On the other hand, viscosity data at high shear rates are more representative of the materials' rheological properties during extrusion. © 2011 Elsevier B.V. All rights reserved.


Liu H.,New Jersey Institute of Technology | Zhu L.,Polymer Processing Institute | Wang P.,University of Rhode Island | Zhang X.,New Jersey Institute of Technology | Gogos C.G.,New Jersey Institute of Technology
Advances in Polymer Technology | Year: 2012

This experimental study examines the evolution of the extent of dissolution of the active pharmaceutical ingredient (API) indomethacin (INM) into the polymer excipient Eudragit E PO (E PO) on four screw configurations processed in an APV 15 mm corotating twin screw extruder. The screws were pulled out and quenched by water, which allowed for quick access to the processed stream carcass. Polarized light microscopy (PLM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR), were employed to investigate the evolution of INM's dissolution into the molten excipient along the extrusion direction. The FT-IR results show that kneading blocks accelerate the complete dissolution process. The unique capability of fully filled kneading blocks in mixing and melting associated with the dissolution of API into polymeric excipient matrix was discussed. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 31: 331-342, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20256 Copyright © 2011 Wiley Periodicals, Inc.


Teng S.,New Jersey Institute of Technology | Wang P.,University of Rhode Island | Zhang Q.,New Jersey Institute of Technology | Gogos C.,New Jersey Institute of Technology | Gogos C.,Polymer Processing Institute
Powder Technology | Year: 2011

The particulate motions and collisions inside the Fluid Energy Mill were simulated by coupling the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). The influences of the operating conditions on the particulate motions and collisions were investigated to further explain size reduction process. The high-speed grinding air streams introduced through narrow inlets selectively accelerate the particles located near the inlets. Those particles are more likely to hit the wall at a high speed, or collide with other particles due to the velocity difference. The simulation results also reveal that abrasion is the dominant breakage mechanism during the particle-particle collisions. On the other hand, with the increase of number of particles in the chamber, the particle-particle collision becomes more important for milling, compared to the particle-wall collision. The side-swipe particle-particle collisions also facilitate transferring of coating materials among particles, which explains the simultaneous milling and coating process recently developed in our lab. © 2011 Elsevier B.V.


Qian Z.,New Jersey Institute of Technology | Wang P.,University of Rhode Island | Gogos C.G.,New Jersey Institute of Technology | Gogos C.G.,Polymer Processing Institute
Polymer Engineering and Science | Year: 2012

A novel simultaneous, in situ milling and coating method carried out in a fluid energy mill (FEM) is applied for the first time to prepare nanoparticle-coated CaCO 3 (CC) additives for polymer composite materials. Simply milled (without coating) CC particles and as-received CC particles were used as references for comparison. The effects of the grinding pressure and the fraction of the nanoparticles on the size and flowability of CC particles were studied. The composites made with polypropylene (PP) and this specially prepared CC have higher elongation at break, elastic modulus, and impact strength, compared with the PP filled with uncoated CC. The thermal and thermo-oxidative stabilities of PP are improved as well by introducing the milled and nanoparticle-coated CC. © 2011 Society of Plastics Engineers.


Yang M.,New Jersey Institute of Technology | Yang M.,Evonik Industries | Wang P.,University of Rhode Island | Gogos C.,New Jersey Institute of Technology | Gogos C.,Polymer Processing Institute
Drug Development and Industrial Pharmacy | Year: 2013

Solid dispersion technologies such as hot-melt extrusion and spray drying are often used to enhance the solubility of poorly soluble drugs. The biggest challenge associated with solid dispersion systems is that amorphous drugs may phase-separate from the polymeric matrix and recrystallize during storage. A more fundamental understanding of drug-polymer mixtures is needed for the industry to embrace the solid dispersion technologies. In this study, a theoretical model based on Flory-Huggins lattice theory was utilized to predict the solubility of a model drug acetaminophen (APAP) in a semi-crystalline polymer poly(ethylene oxide) (PEO) at 300 K. The interaction parameter χ was calculated to be -1.65 from the depression of drug's melting temperature determined from rheological and differential scanning calorimetry analysis. The equilibrium solubility in amorphous PEO was estimated to be 11.7% at 300 K. Assuming no APAP molecules dissolve in the crystalline part of PEO, the adjusted theoretical solubility is around 2.3% considering PEO being 80% crystalline. The solubility of APAP in PEG 400 was calculated to be 14.6% by using the same χ value, close to the experimental measurement 17.1%. The drug's solubility could be altered noticeably by the change of both χ and polymer molecular weight. The study also suggests that the depression of drug's melting point is a good indicator for preliminary polymer screening. The polymer that reduces the melting point the most is likely to be most miscible with the drug. © 2013 Informa Healthcare USA, Inc.


Terife G.,New Jersey Institute of Technology | Wang P.,University of Rhode Island | Faridi N.,Polymer Processing Institute | Gogos C.G.,Polymer Processing Institute | Gogos C.G.,New Jersey Institute of Technology
Polymer Engineering and Science | Year: 2012

The hot melt mixing (HMM) process was used to dissolve 30 wt% of a model drug, indomethacin (INM), in Soluplus® a water soluble polymer excipient. Comprehensive characterization of the HMM-prepared samples, using differential scanning calorimetry, X-ray diffraction, Fourier Transform Infrared spectroscopy, and optical microscopy, strongly suggests that INM was in amorphous state, forming a solid solution with the polymer. Furthermore, to understand the impact of foaming on INM's release profile, the HMM product was foamed in a batch process using supercritical carbon dioxide (CO 2). Dissolution tests of HMM and reference samples were conducted in aqueous solutions with pH 7.4 and 1.2. In all cases INM's release showed strong pH-dependency; faster release and a greater amount of INM was released at pH 7.4 than at pH 1.2. For pure INM and the physical mixture, the drug's ionizable character results in the observed pH-dependency. While for the HMM samples it is also a consequence of theformation of hydrogen bonds between Soluplus® and INM which hinder polymer dissolution at pH 1.2. It was observed that the release rate of INM from different sample types at pH 7.4 decreased in the following sequence: foamed HMM > unfoamed HMM > crystalline INM > physical mixture. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers Copyright © 2012 Society of Plastics Engineers.


Teng S.,New Jersey Institute of Technology | Wang P.,New Jersey Institute of Technology | Zhu L.,Polymer Processing Institute | Young M.-W.,Polymer Processing Institute | And 2 more authors.
Chemical Engineering Science | Year: 2010

In this study, the stochastic method is used to simulate the grinding process in a fluid energy mill: the product particle size distribution is regarded as the result of repeating elementary breakage events, i.e. Mp=M0[Tm]m, where M0 is the row vector of the size distribution of feed particles, Mp is the row vector of the size distribution of product particles, m is the number of elementary steps, and Tm is the matrix of transition probabilities representing the elementary breakage event. The matrix of transition probabilities can be related to the breakage rate function and the breakage distribution function of the elementary breakage event. A specially designed apparatus, named single-event fluid mill, was employed to experimentally estimate those two breakage functions of the elementary breakage event with a breakage rate correction factor θ. The classification effect is taken into consideration by defining a cutting size under which the particle will not break any more. Using this strategy, the product particle size distribution is calculated. The good consistency between the simulation and the experimental results indicates that this model is valid to quantitatively estimate the grinding performance of the fluid energy mill. © 2010 Elsevier Ltd. All rights reserved.


Yang M.,New Jersey Institute of Technology | Yang M.,Evonik Industries | Gogos C.,New Jersey Institute of Technology | Gogos C.,Polymer Processing Institute
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2013

A simple, sensitive, efficient, and novel method analyzing the number of spherulitic nuclei was proposed to estimate the solubility of a model drug acetaminophen (APAP) in poly(ethylene oxide) (PEO). At high crystallization temperature (323 K), 10% APAP-PEO had the same low number of spherulitic nuclei as pure PEO, indicating that APAP and PEO were fully miscible. At low crystallization temperature (303 K), the number of nuclei for 10% APAP-PEO was significantly higher, suggesting that APAP was oversaturated and therefore recrystallized and acted as a nucleating agent. Based on the results obtained, the solubility of APAP in PEO is possibly between the concentration of 0.1% and 1% at 303 K. The spherulitic growth rate G of PEO was found to decrease with increasing APAP concentration, suggesting that APAP is most likely functioning as a chemical defect and is either rejected from or included in the PEO crystals during chain folding. APAP could possibly locate in the inter-spherulitic, inter-fibrillar, inter-lamellar, or intra-lamellar regions of PEO. At 323 K, the morphology of 10% APAP-PEO is more dendritic than spherulitic with large unfilled space in between dendrites and spherulites, which is a sign of one or the combination of the four modes of segregation. An extensive spherulitic nucleation and growth kinetics study using the classical theoretical relationships, for example, the Hoffman-Lauritzen (HL) and Avrami theories, was conducted. Both microscopic and differential scanning calorimetric (DSC) analysis yielded similar values for the nucleation constant Kg as well as the fold surface free energy σe and work of chain folding q. The values of σe and q increased with APAP concentration, indicating that the chain folding of PEO was hindered by APAP. © 2013 Elsevier B.V. All rights reserved.


Mou H.,East China University of Science and Technology | Shen F.,Polymer Processing Institute | Shi Q.,East China University of Science and Technology | Liu Y.,East China University of Science and Technology | And 2 more authors.
European Polymer Journal | Year: 2012

In this work, an inorganic metal salt, zinc chloride (ZnCl 2), was mechanically mixed with nitrile butadiene rubber (NBR) to prepare a novel crosslinkable NBR/ZnCl 2 composite. ZnCl 2 was found to dissolve into NBR upon heating to a designed temperature, which was considered as a result of dissolution process induced by the occurrence of coordination reaction. Consequently, the morphology of the composite could change from an obvious two-phase structure to a macro-homogeneous phase structure. The determination of the coordination bonding in NBR/ZnCl 2 composite was done by Fourier transform infrared spectroscopy. The crosslinking procedure of the composite was investigated by dynamic mechanical analysis and differential scanning calorimetry. A Kissinger's method was used to calculate the active energy. Other characterizations including scanning electron microscopy, elemental analysis, X-ray Diffraction and polarized microscope with a hot stage were used to investigate the morphology of the composite. Furthermore, the resulting material possessed special and excellent tensile properties. © 2012 Elsevier Ltd. All rights reserved.

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