Recycling Of Polyurethane Foam Research Articles

Recycling Of Polyurethane Foams: A Strategy in Waste Management and Control

This study presents crop coefficient (Kc) values of TMV1-ST maize variety cultivated under deficit irrigation scheduling in Mkoji sub-catchment, Tanzania. Field experiments consisting of eight (8) treatments were conducted in 2004 and 2005 irrigation seasons. The treatments variation was irrigation intervals. The control treatment was irrigated on weekly basis while the other treatments were irrigated every other week at one or more growth stages of the maize crop. Surface irrigation method was used and soil moisture contents were monitored weekly throughout the crop growing season from which weekly crop actual evapotranspiration was computed. Weather data of the study location were used to compute weekly reference evapotranspiration based on the FAO-Penman- Monetieth model. Crop coefficients were computed as the ratio of crop actual evapotranspiration of the different treatments to reference evapotranspiration on weekly basis. Water stress coefficients were also computed. The crop coefficients had similar trend in the two seasons which make them reliable. The average crop coefficient (Kc) of the fully irrigated treatment for the two seasons for the establishment, vegetative, flowering and grain filling stages were 0.53,0.82,1.10, and 1.06, respectively, while the average crop coefficients of the deficit irrigated treatments (Kc') for the two seasons for the establishment, vegetative, flowering and grain filling stages were 0.53, 0.75, 0.94, and 0.78, respectively. Withholding regular irrigation at any crop growth stage reduced crop coefficient by between 17 to 30 %, while withholding regular irrigation at two or more successive growth stages of the maize crop reduced crop coefficient by about 40 %. The water stress coefficient (Ks) resulting from deficit irrigation at any one growth stage only of the maize crop were found to range from 0.74 to 0.83, while deficit irrigation at two or more successive growth stages ranged from 0.68 to 0.77. The crop and water stress coefficients developed from this study could be used in irrigation systems planning and design for the study area in Tanzania.

Serum Levels of Polybrominated Diphenyl Ethers (PBDEs) in Foam Recyclers and Carpet Installers Working in the United States

Increased exposure to the flame retardants known as polybrominated diphenyl ethers (PBDEs) may be expected to occur during the recycling of polyurethane foam containing these chemicals. To date, no studies in the United States have investigated occupational exposure to these flame retardants during recycling processes. The objective of the present study was to determine if individuals working in foam recycling facilities, and/or carpet installers who may install carpet padding manufactured from recycled foam, possess significantly higher PBDE serum levels relative to that of the general U.S. population. As a control group, serum was collected from four spouses and one clerical worker. In addition, levels in workers were also compared to the recently published national health and nutrition examination survey (NHANES) data set on PBDEs in the general U.S. population. Serum samples were collected in duplicate and analyzed by two different laboratories as quality control. Total PBDE levels were found to be significantly higher (p < 0.05) in the individuals recycling foam and installing carpet (n = 15) relative to the control group (n = 5). Median sigmaPBDE levels in the foam recyclers, carpet layers, and control group were 160, 178, and 19 ng/g lipid, respectively. In contrast, concentrations of a polybrominated biphenyl (BB-153) and a polychlorinated biphenyl (CB-153) were equivalent among all groups tested. The PBDE congeners BDE-47, 99, 100, and 153 contributed 90% of the sigmaPBDE concentration in serum and no differences in congener patterns were apparent among the different groups. Relative to concentrations measured in the NHANES, foam recyclers and carpet layers have body burdens that are an order of magnitude higher. These data suggest individuals recycling foam-containing products, and/ or using products manufactured from recycled foam (i.e., carpet padding), have higher body burdens of PBDEs, and thus may be at higher risk from adverse health effects associated with brominated flame retardant exposure.

Continuous Process for Recycling of Polyurethane Foam

The investigation deals with the recycling of high resiliency polyurethane (PU) foam by the application of high-power ultrasound in a continuous ultrasonic reactor. The foam has been decrosslinked at various screw speeds and various amplitudes, then blended at different ratios with the virgin polyurethane rubber (PUR) and cured. The die pressure and the total power consumption have been recorded as a function of processing conditions. Rheological and mechanical properties, hardness as well as gel fraction and crosslink density of the decrosslinked foam and cured blends have been measured and compared in an attempt to find out the optimum condition for decrosslinking. Blends have also been prepared using different proportions of ground samples and virgin rubber, and a comparison of the properties between these blends and the blends of the decrosslinked foam has been carried out. The results show that compared to the ground samples, the blends of the decrosslinked samples are easier to mix and exhibit enhanced properties.

Performance of MDI Pour-in-Place Automotive Seating Incorporating Recycled Content

Increasingly, the automotive industry is requiring demonstration that polymers in automotive applications are recyclable. The techniques for the recovery and recycling of polyurethane foam from MDI Pour-in-Place automotive seating have been demonstrated. This seating technology is uniquely suited to the recovery of foams for physical and chemical recycling. The pulverization of flexible foam and its physical recycling back into automotive seating is described with estimations of the costs involved and performance of the resulting product. Recent work on the chemical recycling of MDI automotive seating is outlined.