Maureen Dever

Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends

In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially oriented films showed an increase in tensile strength, modulus, and strain-at-break.

Outdoor Weathering Evaluation of Carbon-Black-Filled, Biodegradable Copolyester as Substitute for Traditionally Used, Carbon-Black-Filled, Nonbiodegradable, High-Density Polyethylene Mulch Films

Carbon-black-filled, biodegradable, copolyester mulch film (Eastar®, or EA, Tennessee Eastman, Kingsport, TN) and commercial carbon-black-filled, high-density polyethylene (HDPE) mulch film were exposed for 12 weeks to commercial vegetable crop growing conditions by being placed directly on irrigated soil in the field of the University of Tennessee Alcoa Highway State Agriculture Experiment Station (Knoxville, TN) and by being placed on a plywood exposure rack as described by the American Society of Testing and Materials (ASTM) Standard Test Method 1435: Outdoor Weathering of Plastics. Mechanical properties and weather information were collected in order to evaluate the feasibility of using the newly developed biodegradable EA mulch film to replace the nonbiodegradable HDPE mulch film. Results indicate that the EA mulch film exhibited favorable tensile strength and elongation-at-break during outdoor exposure rack testing and outdoor, in-field, placed directly on the soil, exposure testing, suggesting biodegradable EA could be a substitute for the HDPE nonbiodegradable material.

Rheology of Lyocell Solutions from Different Cellulose Sources

Rheological measurements were used to characterize the behavior of lyocell solutions, i.e., cellulose dissolved in N-methymorpholine-N-oxide. Cellulose sources included dissolving pulp, kraft pulp, sugar cane fibers, and kenaf fibers. The dominance of viscous behavior, G′ values, over elastic behavior, G″ values, is affected by cellulose concentration and molecular weight. At lower concentrations and degrees of polymerization (DP), dissolving pulp solutions show viscous, inelastic behavior at low frequencies. At higher concentration and DP, dissolving pulp solutions are more elastic at higher frequencies. Solutions prepared with kenaf and sugar cane fibers show similar properties to those using pure dissolving pulp, and comparisons suggest the molecular weight and/or the presence of other substances such as lignin in the cellulose from these alternative sources affect the rheology.

Analysis of a Thin Activated Carbon Loaded Adsorption Medium

Abstract Thin adsorption media are being investigated for use in a variety of applications including protective clothing for military use and hazardous waste cleanup, as well as in indoor air quality within a variety of filtration media. The objective of this study was to evaluate the dynamics of adsorption of a chlorinated organic gas on activated carbon impregnated meltblown laminates. The adsorption data were collected on a bench scale test stand on an existing battle dress overgarment and an experimental activated carbon impregnated liner material for use in protective clothing. Activated carbon loadings were nominally 40, 80, and 120 g/m2. This paper reviews the results of the study and compares the experimental results to existing adsorption theory. For the organic compound, trichloroethylene, which was studied, a favorable isotherm was found. Although the materials were thin, the media provided a finite breakthrough, defined as a 1% penetration, followed by a gradual breakthrough curve similar to t...

Lyocell Solutions from Alternative Cellulose Sources

Lyocell fibers, a generic subclass of rayon fibers, are produced from cellulose dissolved in N-methylmorpholine oxide (NMMO). The lyocell solutions typically consist of blends of cellulose from similar low and high degree of polymerization (DP) dissolving pulps to achieve desired spinnability and fiber properties. The objective of this research was to determine if alternative lower value cellulose sources could be used as raw materials for lyocell by characterizing solutions made from these sources. Shear viscosity, which strongly affects spinning of fibers, of ten cellulose sources at four concentrations was compared to that of five industrial dissolving pulp standards with DPs from 670 to 1720. Bleaching, concentration, cellulose source, and their interactions had significant effects on shear viscosity. Kudzu, sugarcane bagasse, recycled, and thermomechanical cellulose pulps had higher viscosities than did the more highly processed hardwood and softwood. Bagasse was similar to the lowest DP dissolving pulp standard. Recycled and thermomechanical pulps were similar to the higher DP standard and bleaching affected the shearing behavior of these less pure pulps. Shear viscosity measurements were effective in determining differences among the pulps.

Effects of Microwave Irradiation on Attagenus Unicolor (Brahm) (Coleoptera: Dermestidae) and the Physical and Chemical Properties of Wool

A nonchemical method is reported for the disinfestation of all life stages of the black carpet beetle Attagenus unicolor (Brahm) on wool. This method is based on microwave irradiation using a 2.54 GHz frequency multimode microwave oven op erating at full power (1580 AC watts). All life stages (egg, larva, pupa, and adult) of the black carpet beetle were exposed to microwaves. The results showed that two minutes of microwave exposure was sufficient to kill (100% mortality) all life stages with minimal effects on the physical and chemical properties of the wool.

Conversion of Recycled Polymers/Fibers Into Melt-Blown Nonwovens

Abstract Being a simple one-step process for converting polymer directly into a nonwoven fabric, melt blowing is ideally suited for processing of several recycled plastics. The process uses hot air to draw the fibers and does not require precise, individual control of each filament as in the conventional fiber-spinning processes. Recycled polypropylenes (PPs) from several sources were investigated as candidates for melt blowing. Waste from spun-bond line and spun-bond-melt-blown-spun-bond (SMS) fabrics were pelletized and then melt blown at our facility. The feasibility of using a melt-blowing line with an extruder gear pump unit to remelt the waste fibers/web and feed it with the molten virgin polymer stream coming from the main extruder was explored. A 1000 MFR virgin PP resin and fabrics produced from that polymer were used for this investigation. Fabrics were characterized in all the cases for their performance properties. Some of the relevant data are reported here. It was observed that in most of th...

Investigation of the effect of a topically applied tackifier in reducing particle bounce in a melt-blown air filter

Many commercially available indoor air filters are currently being marketed with tackifier filter adhesives applied to the surface of the fibres or to the face of the filters. However, little information is available in the literature concerning the application of these tackifiers, and their effectiveness in reducing particle penetration through filters. It is of scientific value to investigate the efficacy of such tackifiers, especially in the light of increasing concern for indoor air quality. The paper presents the ongoing results of an investigation in which polypropylene melt-blown media were manufactured under a variety of operating conditions, to produce media which might be suitable for use in indoor air quality filters. The filter media were prepared at the Textiles & Nonwovens Development Center (TANDEC), and tested for filtration efficiency in the Air Quality Laboratory housed in the Department of Civil & Environmental Engineering at the University of Tennessee, Knoxville. Efficiencies were determined using both cold, polydispersed dioctylpthalate (DOP), as well as monodispersed latex particles (0.6 to 3.0 μ) using an ASTM 1215 filtration test stand. The objectives of the research were to determine the initial efficiency of the media at velocities ranging from 3 to 375 cm/s, and to compare the measured results with filtration theory. At the higher velocities, typical of those used in indoor air filters, the experimental efficiencies using dry particles were significantly less than both the DOP and theoretical efficiencies, because of the kinetic energy of the particles, which resulted in particle bounce. Empirical corrections were developed as a function of the kinetic energy to account for the decreased efficiency resulting from particle bounce, and are presented. Tests were also conducted on a melt-blown medium in which the fibres were coated with various loadings of a tackifier, referred to here as being ‘topically’ applied. The results showed that the efficiencies at high velocities were improved as a result of the reduction in particle bounce, while the efficiencies at low velocities were unchanged even though larger effective fibre diameters resulted from application of the tackifier.