Hydrophilic polymers in a swellable matrix tablet hydrate quickly to form a hydrogel layer on the exterior of the dosage once in contact with water or biologic fluid. The resultant hydrogel serves as a barrier to regulate water permeation into the matrix and drug diffusion from the preparation. It is therefore important to understand how the polymer is hydrated and what mechanism exists between hydrogel formation and drug dissolution from a swellable matrix tablet. In this thesis, a TA texture analyzer was utilized to monitor and characterize matrix swelling properties during dissolution process. Multiple regression models were employed to analyze the quantitative relationship between drug dissolution or hydrogel thickness and major formulation factors (polymer ratio, drug solubility). Modified release matrix tablets were prepared using four APIs with a range of aqueous solubility, i.e., acetaminophen (ACE), chlorpheniramine (CHL), ibuprofen (IBU), and pseudoephedrine hydrochloride (PSE). Two hydrophilic polymers, polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) were selected and tested as primary matrix polymers for the formulations. It was found from the experiments that multiple regression model was capable of estimating drug dissolution for both PEO and HPMC matrix preparations. Based on major formulation factors the regression models provide satisfactory prediction of drug release, which could further aid in formulation development and optimization.

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No description available.

An investigation has been carried out to reduce the deformation behavior of polyethylene (PE) woven geotextile fabric by making PE fabric-glass yarn composite structure using stitching and laminating. The results showed that reinforcement significantly reduced the creep and IED as long as the tensile stress is lower than the total load bearing capacity of the glass yarns in the composite structure. However, the strength of PE-glass composite fabric was solely dependent on the strength of the glass yarns. The strength from PE yarns only contributes when all glass yarns are broken. Cast result of concrete columns using the glass yarn reinforced PE fabric by stitching method suggested that the glass yarn must face outside of the fabric formwork to avoid damage of both fabric surface and column surface.

A computational model for the prediction of articular and backside polyethylene (PE) wear of total knee replacements (TKRs) could enable the optimization of TKRs for the reduction of polyethylene wear, thereby improving the long term success of TKRs. A finite element model was developed for the TKR and the results were implemented in a computational wear model to assess PE wear. The wear factors of Archard’s wear law were identified by implementing the finite element simulation results along with knee simulator wear test results. Archard’s wear law was found to have insufficient accuracy for the purpose of optimization. Therefore, a novel computational wear model was developed by the author based on a theoretical understanding of the molecular behavior of PE. The model predicted result fell within the standard deviation of the independent knee simulator wear test results, indicating a high level of accuracy for the novel computational wear model.

Hydrophilic polymers in a swellable matrix tablet hydrate quickly to form a hydrogel layer on the exterior of the dosage once in contact with water or biologic fluid. The resultant hydrogel serves as a barrier to regulate water permeation into the matrix and drug diffusion from the preparation. It is therefore important to understand how the polymer is hydrated and what mechanism exists between hydrogel formation and drug dissolution from a swellable matrix tablet. In this thesis, a TA texture analyzer was utilized to monitor and characterize matrix swelling properties during dissolution process. Multiple regression models were employed to analyze the quantitative relationship between drug dissolution or hydrogel thickness and major formulation factors (polymer ratio, drug solubility). Modified release matrix tablets were prepared using four APIs with a range of aqueous solubility, i.e., acetaminophen (ACE), chlorpheniramine (CHL), ibuprofen (IBU), and pseudoephedrine hydrochloride (PSE). Two hydrophilic polymers, polyethylene oxide (PEO) and hydroxypropyl methylcellulose (HPMC) were selected and tested as primary matrix polymers for the formulations. It was found from the experiments that multiple regression model was capable of estimating drug dissolution for both PEO and HPMC matrix preparations. Based on major formulation factors the regression models provide satisfactory prediction of drug release, which could further aid in formulation development and optimization.

High density polyethylene (HDPE) is a widely used plastic but it is also a combustible material. One way of reducing flammability is to add fillers, such as magnesium hydroxide (Mg(OH)2). However, this has a deleterious effect on the mechanical properties of composites. It has been found that one possible method of restoring mechanical properties is to modifY the filler particles with coating agents, such as stearic acid. In the present work, this idea was taken a stage further with the use of various metal stearates (e.g. magnesium stearate, calcium stearate, and zinc stearate) for modifying filler. The fillers examined were magnesium hydroxide and calcium carbonate. A filler loading of 40% w/w was used in all samples. Samples were moulded into a variety of shapes for mechanical testing. Such tests included, tensile, flexural, and impact testing. To obtain deeper understanding of the effect of the coating agents on the fillers, a variety of fundamental tests were carried out. These included Diffuse Reflectance FTIR (DRIFT), Thermal Analysis using a DSC cell, Xray Diffraction (XRD), contact angle measurement. Unfilled HDPE, uncoated filled-HDPE, and coated filled-HDPE were compared using uncoated filled-HDPE as a base line. Uncoated filled-HDPE is more brittle than unfilled HPDE. Surface modification of filler improves the toughness properties. Comparing coated filled-compounds, stearic acid and zinc stearate caused a small improvement, magnesium stearate improved the properties significantly with calcium carbonate while calcium stearate gave the best results for coating magnesium hydroxide. One monolayer coating gave the best compound properties compared to other degrees of coating. Although, tensile/flexural strength was not greatly affected elongation at yield, extension at maximum load, and impact properties increased significantly. DSC was used to observe the disappearance and conversion of coating agents as coating proceeded. X-ray diffraction showed the effect of injection moulding on the orientation of the filler and polymer. During coating of the filler particles, XRD and DSC were used to follow incorporation of stearate particles to produce the monolayer coverage. Surface free energy results showed that surface modification of filler resulted in the reduction of hydrophilicity of filler leading to tougher composites compared with uncoated filled-compounds.

A microwave assisted methodology was developed to modify Merrifield resins (1-2% cross-linked containing 1.0-3.5 mmol Cl-/g) with different nominal molecular weights PEG (200-1000). The synthesis was also carried out by conventional heating to assess the differences between the two procedures. The most efficient synthesis was achieved by using microwave and by using PEG with molecular weight 200 and MR 2% crosslinked containing 1.25 mmol Cl -/g. The structural elucidation was carried out using Fourier transform infrared (FTIR) spectroscopy and elemental analyses. Upon pyrolsis-GC/MS analysis of the PEGylated MR, the PEG showed the tendency to undergo thermal degradation by the loss of a smaller PEG fragments. This observed degradation of PEG was less prominent during microwave assisted synthesis compared to conventional heating, in addition to faster reaction rates and higher yields. As expected, the PEGylated MR showed improved swelling properties in polar solvents. The chemical reactivity of the PEGylated Merrifield resin was confirmed by the esterification with pyruvic acid and by the substitution of hydroxyl group using thionyl chloride. In addition, the PEGylated MR was converted into (1) polymer-supported acid/base or redox indicator by the attachment of a blue organic dye - 2,6-dichloroindophenol (DCIP) through a nucleophilic substitution reaction and (2) beta-cyclodextrin trap, a water insoluble inclusion-complex, by immobilization of beta-cyclodextrin through cross-linking with 1,6-hexamethylene diisocyanate reagent.

This study examines composite materials prepared from ground recycled tires (tire crumb) and post-consumer recycled high density polyethylene (HDPE). An initial set of composites was prepared from as-received tire crumb and HDPE recyclate containing 040% tire crumb in 10% increments, using injection moulding. The elastic modulus and tensile strength were found to decrease linearly with increasing tire crumb content. Addition of tire crumb to recycled HDPE caused produced an immediate reduction in the strain to failure with a progressively more modest decrease as the tire crumb content was increased. The impact toughness decreased more linearly with increasing tire crumb fraction. Cross sections of the composites showed that the tire crumb particles were in intimate contact with the matrix but post mortem examination of the fracture surface of the impact test specimens indicated that the level of bonding had been poor. A second set of composites was a prepared from 10% tire crumb. The tire crumb was first given an oxidative treatment in hot aqueous copper chloride at concentrations from 0-5 wt% Cu Ch at 50 or 100??C for 6 or 12 hours. The composites were injection moulded with an addition of 0.5 wt% dicumyl peroxide (DCP). These composites showed good bonding between the tire crumb and the recycled HDPE even at concentrations of 0% of the Cu 2+ oxidation catalyst. The addition of DCP was found to substantially reduce the modulus of neat HDPE and this reduction was reflected in the modulus of the composites. It was found that the DCP concentration could be reduced to 0.02% without adversely affecting the composites.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: Andrew Hrymak. Includes bibliographical references (leaves 157-168). Also available online.