Conversion of Recycled Polymers/Fibers Into Melt-Blown Nonwovens

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 the cases, fabrics with good properties could be produced at high throughputs, thus demonstrating that most of the plant waste can be reused.     

Indoor Air Quality Investigations at Five Classrooms

Abstract Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO₂), sulphur dioxide (SO₂), nitric oxide (NO), nitrogen dioxide (NO₂), particulate matter with diameter less than 10 mm (PM₁₀), formaldehyde (HCHO), and total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM₁₀ concentrations exceeded the Hong Kong standards, and the maximum indoor PM₁₀ level was even at 472 μ;g/m³. Air cleaners could be used in classrooms to reduce the high PM₁₀ concentration. Indoor CO₂ concentrations often exceeded 1,000 μl/l indicating inadequate ventilation. Lowering the occupancy and increasing breaks between classes could alleviate the high CO₂ concentrations. Though the maximum indoor CO₂ level reached 5,900 μl/l during class at one of the sites, CO₂ concentrations were still at levels that pose no health threats.     

Legacy contaminant-stable isotope-age relationships in Lake Ontario year-class Alewife (Alosa pseudoharengus)

Alewife (Alosa pseudoharengus) are the preferred prey species of the top piscivore predators in the Lake Ontario food web and are an essential constituent in the bioaccumulation of persistent organic contaminants. Year-class samples collected in 2016 represent the alewife age ranges of 2015 (Age-01) sequentially dating back to 2008 (Age-08). The most abundant contaminant measured in Lake Ontario alewife (151.5 ng/g) were total polychlorinated biphenyls (PCBs), increasing at a rate of 11.8 ng/g per year on an age-averaged concentration basis. Total mercury demonstrated the largest percent increase (240%) accumulated over alewife ages of 1–8 years. Average total concentrations of the most abundant polychlorinated dibenzo-p-dioxin isomer (2378-tetrachlorinated dibenzo-p-dioxin (TCDD), 1.3 pg/g) and polychlorinated dibenzofuran isomer (2378-tetrachlorinated dibenzofuran (2378-TCDF), 6.6 pg/g) comprised most of the overall total dioxin (2.5 pg/g) and total furan concentrations (8.7 pg/g). The vast majority (69%) of alewife total toxic equivalence (TEQ) was comprised of the non-ortho coplanar PCBs. Both mammal and avian wildlife protection values based on total TEQ were uniformly exceeded for the dioxin-like compounds measured in Lake Ontario alewife. Ontogenetic dietary influences expressed a significant impact on Age-01 alewife age-contaminant relationships and age-stable isotope concentrations and trends for legacy contaminants. Total Hg and all dioxin-like contaminants did not demonstrate the Age-01 ontogenetic dietary effects found in legacy contaminants. A prominent polychlorinated naphthalene (PCN) concentration peak measured in year-class Age-04 alewife was followed by a corresponding lake trout peak 3–4 years later illustrating a unique example of trophic-level contaminant uptake and concomitant integration delay.     

Role of local governments in fostering the development of an emerging industry: A market-oriented policy perspective

This research investigates the role of local governments in stimulating an emerging industry and focuses on the specific growth of the new energy vehicle industry in Hangzhou, China. This research confirms that enabling firms to access emerging technology, acquire financial support, and touch customers and/or suppliers are critical to foster the emergence and development of industries. Moreover, the primary contribution of this study is to emphasize the support of the local government in the development of emerging industries on the perspective of the creation of a large-scale market demand. The creation of large-scale market demand may inspire actors to be proactive in responding to these incentives; thus, public and private actions may help increase the accessibility to technology, infrastructure, and finances. Hence, a market-oriented policy that incentivizes the creation and expansion of market demand among diverse public and private actors should be seen as the key issue for the emergence and growth of emerging industries. Policies should also be adopted promptly with the development of the market.     

Effect of mixer geometry and operating conditions on mixing efficiency of a non-Newtonian fluid in a twin screw mixer

The effect of mixer speed, fluid inflow rate, and paddle angle was examined in a shortened geometry. 3D FEM simulation of non-Newtonian 2 g/100 mL carboxymethyl cellulose aqueous solution in the mixing region of a Readco continuous mixer was performed. Data gathered included velocity vectors, shear rate, and mixing index. Increasing mixer speed increased velocity magnitudes in the horizontal and vertical directions. Fluid inflow rate had little impact on velocity in the horizontal and vertical directions, but increased velocity in the axial direction and elongational contribution to the mixing index. All configurations showed areas of simple shear flow where the fluid experienced high shear rates. Staggering paddles increased the maximum axial velocity and shear rate. When successive paddles on the same screw are parallel, a zone was seen between the center of the paddle and the barrel wall which demonstrated efficient dispersive mixing.