The following literature review has been originally conducted as part of the Waste plastic extruder for Mech 461. It now supports the Recyclebot project. Please add content.
Collection, transfer and transport of waste: accounting of greenhouse gases and global warming contribution[edit | edit source]
Eisted, R., Larsen, A., and Christensen, T., 2009, "Transfer and Transport of Waste: Accounting of Greenhouse Gases and Global Warming Contribution," Waste Management & Research, 27(8) pp. 738-745.
Abstract:
The collection, transfer and transport of waste are basic activities of waste management systems all over the world. These activities all use energy and fuels, primarily of fossil origin. Electricity and fuel consumptions of the individual processes were reviewed and greenhouse gases (GHG) emissions were quantified. The emission factors were assigned a global warming potential (GWP) and aggregated into global warming factors (GWFs), which express the potential contribution to global warming from collection, transport and transfer of 1 tonne of wet waste. Six examples involving collection, transfer and transport of waste were assessed in terms of GHG emissions, including both provision and use of energy. (GHG emissions related to production, maintenance and disposal of vehicles, equipment, infrastructure and buildings were excluded.) The estimated GWFs varied from 9.4 to 368 kg CO2-equivalent (kg CO2-eq.) per tonne of waste, depending on method of collection, capacity and choice of transport equipment, and travel distances. The GHG emissions can be reduced primarily by avoiding transport of waste in private cars and by optimization of long distance transport, for example, considering transport by rail and waterways.
Notes:
- provide LCA of transport, collection and transfer for waste
- GHG emissions and Global Warming Potential of these activities under various conditions.
- greatest for rural and remote areas, or situations where individuals drop waste at a central point. Lower for urban areas and curbside collection. Still some emissions in each scenario.
Municipal Solid Waste Management: Can Thermodynamics Influence People's Opinions about Incineration?[edit | edit source]
Norman Kirkby and Adisa Azapagic, "Municipal Solid Waste Management: Can Thermodynamics Influence People's Poinions about Incineration?," in Sustainable Development in Practice, vol. 1, 1 vols. (John Wiley and Sons Ldt., 2004), 117-200.
- each person produces an average of 500 kg of solid waste per year
- developed countries produce twice as much as undeveloped countries
- reusing and recycling waste to recover materials is a sustainable way to deal with municipal solid waste - difficult because of high costs of collection/sorting/recycling
- MSW in U.S is 10.7% plastic
- MSW in Mexico is 4.4% plastic
- Asia - slum areas often denied waste collection services
- Africa - lack of financial resources, trained staff, and poor enforcement of legislation
Factors influencing waste separation and utilization among households in the Lake Victoria crescent, Uganda[edit | edit source]
Ekere, W., Mugisha, J., and Drake, L., 2009, "Influencing Waste Separation and Utilization among Households in the Lake Victoria Crescent, Uganda," Waste Management, 29(12) pp. 3047-3051
Abstract:
Wastes, which are the by-products of consumption, are a growing problem in the urban and peri-urban areas of the Lake Victoria region largely due to high urban population growth rates, consumption habits, low collection rates and hence waste accumulation. Whereas the biodegradable proportion is high and could be reutilized, a few have tapped the economic potential of this waste. This study was conducted to explore the potential alternatives and determinants of waste separation and utilization among urban and peri-urban households in the Lake Victoria crescent. A random sample of households in five urban and peri-urban areas of the crescent were selected and surveyed. Logit models were used to establish the factors influencing waste separation and utilization in urban and peri-urban areas of the lake crescent. Results indicate that, gender, peer influence, land size, location of household and membership of environmental organization explain household waste utilization and separation behaviour. Campaigns for waste separation and reuse should be focused in the peri-urban areas where high volumes of wastes are generated and accumulate. Social influence or pressure should be used to encourage more waste reuse and separation.
Notes:
- evaluation of waste separating practices in region of Uganda.
- attempts to explain factors contributing to compliance with separation and recycling guidelines.
- Mention of profit gaining activities using recycled goods.
Stability of ABS compounds subjected to repeated cycles of extrusion processing[edit | edit source]
Karahaliou, E. -., and Tarantili, P. A., 2009, "Stability of ABS Compounds Subjected to Repeated Cycles of Extrusion Processing," Polymer Engineering & Science, 49(11) pp. 2269-2275
Notes:
- No changes found in ABS mechanical properties through 5 extrusion cycles
- Some changes in colour and chemical composition indicate that two parallel processes may be occurring which balance each other, but no conclusive evidence.
- indicates ABS should be useful for RepRap through multiple use cycles.
Energy Audit of Kerbside Recycling Services[edit | edit source]
Metcalfe, P. (2008) "Audit of the Kerbside Recycling Services." The London Borough of Camden. Energy Audit Camden Report 3. ADAS, Wolverhampton, UK.
Notes:
- includes graphs showing percentage of GHG from recycling process in Camden results from transport and collection.
- new system implemented from study has greatly reduced collection impact, but it is still significant.
The ecological relevance of transport in waste disposal systems in Western Europe[edit | edit source]
Salhofer, S., Schneider, F., and Obersteiner, G., 2007, "Ecological Relevance of Transport in Waste Disposal Systems in Western Europe," Waste Management, 27(8) pp. S47-S57.
Abstract:
With the development of modern waste management systems in Western Europe, a remarkable increase in the distances for waste transportation has been observed. The question thus arises whether recycling with longer transport distances is ecologically advantageous or whether disposal without recycling is to be preferred. This situation was analysed using selected product and waste streams. This included refrigerators, paper, polyethylene films and expanded polystyrene. For each of these streams, a life cycle analysis was conducted with an emphasis on waste transport. The system boundaries were set in terms of the generation of waste to recycling or landfilling. The comparison included several scenarios with recycling and different transport distances. Landfilling was used as the reference scenario. The results obtained demonstrated how transport distances influence the ecological benefit of recycling. In the case of expanded polystyrene, the ecological boundaries are reached in practical situations, while with other materials these boundaries are far from being attained. In these cases, more complex and elaborate collection schemes, such as kerbside collection, which is economically convenient and shows the highest collection rates, can also be recommended.
Notes:
- wide range in results based on material transported and availability of recycling materials.
- for HDPE films, found transport accounted for 1%-11% of GHG and GWP.
- in almost all cases, impact less for recycling than landfilling.
Life cycle assessment of a plastic packaging recycling system[edit | edit source]
Arena, U., Mastellone, M., and Perugini, F., 2003, "Life Cycle Assessment of a Plastic Packaging Recycling System," The International Journal of Life Cycle Assessment, 8(2) pp. 92-98.
Abstract:
Goal, Scope and Background. The object of the study is the Italian system of plastic packaging waste recycling, active until 2001, that collected and mechanically recycled the post-consumer PE and PET liquid containers. The phases of collection, compaction, sorting, reprocessing and refuse disposal were individually analysed and quantified in terms of energy and material consumptions as well as of emissions in the environment. The work is the result of a joint research project with the Italian Consortium for Packaging (CONAI), carried out in co-operation with the main Italian companies active in the field. The main aim was the quantification of the real advantage of plastic container recycling and the definition of criteria, at the same time environmentally compatible and economically sustainable, for their management. Main Features For each of the unit processes, and in order to increase the data quality, all the data of interest were collected during technical visits to several selected plants active in Italy or deduced by official documents and certificate declarations of the same companies. To allow comparison of resource consumption and environmental pollution from different management scenarios producing different products, thebasket of products method was applied. Results The results indicates that the production of 1 kg of flakes of recycled PET requires a total amount of gross energy that is in the range of between 42 and 55 MJ, depending on whether the process wastes (mainly coming from sorting and reprocessing activities) were sent or not to the energy recovery. The same quantity of virgin PET requires more than 77 MJ. The energetic (and then environmental) saving is so remarkable, even for PE, being 40–49 MJ for the recycled polymer and about 80 MJ that for the virgin polyolefin. The calculations were made with the reasonable assumption that the final utilisation can use the virgin or the recycled polymer without any difference. Conclusions and Outlook The analysis defined and verified a suitable tool in the field, based on objective data, for comparing different coherent scenarios of waste management politics. This allows one to propose the extension of the tool under different collection schemes, as well as for different systems of packaging recycling. As an immediate consequence of the success of the present study, the joint-research programme with CONAI has been extended for another three years. The focus will be the Italian system for paper and paperboard recycling and that for all plastic packagings. In parallel, a different study has been scheduled with reference to the integrated solid waste management of the Regione Campania, the largest and most populated area in the South of Italy.
Notes:
- transportation and collecting found to have the biggest environmental impact on the recycling process.
Small scale recycling of plastic waste[edit | edit source]
H. Vest, "Small scale recycling of plastic waste," Appropriate Technology, vol. 29, pp. 51-53, January-March, 2002. Available online here
- originally written in 1995, published in Appropriate Technology in 2002. Open source - available online at URL above.
- speaks to potential of plastics recycling to be a profitable venture in developing countries due to low labour cost
- description of recycling process for various plastic types
- outline of existing technology (extruders, pelletizers, manual injection moulding, etc.)
- larger scale than targeted for this project (i.e. commercial vs. domestic).
- raises concern of difficulty of sorting plastics, though notes it can be done by eye with experience.
- sorting is necessary for high quality feedstock
Reactive Extrusion of Recycled Bottle Waste Materials[edit | edit source]
R. Hettema, J. Pasman, L.B.P.M Janssen, "Reactive Extrusion of Recycled Bottle Waste Materials", Polymer Engineering and Science, April 2002, Vol. 42, No. 4.
- States challenges of plastic recycling
- mixing waste streams (ie. HDPE and PP) results in undesirable engineering properties.
- hard to recreate properties of virgin material
- Authors conducted experiments with reactive extrusion (chemicals added during process)
- peroxides added during extrusion process.
- found to be beneficial in improving properties such as toughness
- Extrusion settings also tested for effects on material properties.
- mass flow rate, screw speed and termperature tested.
- linkage found between these parameters and % elongation, Young's modulus and yield strength.
Relevance
- Reactive extrusion could be explored to improve properties of expanded materials. Need to ensure such chemicals are domestically available in a development setting.
- Extrusion parameters will have to be tested to determine optimal conditions for quality feedstock production.
Plastics recycling and waste management in the US[edit | edit source]
Subramanian, P. M., 2000, "Plastics Recycling and Waste Management in the US," Resources, Conservation and Recycling, 28(3-4) pp. 253-263.
Abstract:
The increasing awareness of the environment has contributed to concerns regarding our life styles and our indiscriminate disposal of wastes. During the last decade, we have been trying to address this complex problem, more aggressively. Discussed here briefly, are our efforts in the United States in addressing the issue of solid wastes and in particular, plastic wastes. These efforts have begun to show promising results. The municipal solid waste (MSW) produced annually, has begun to decrease, e.g. from 211.5 million tons in 1995 to 209.7 million tons in 1996. Recycling rates and composting rates are increasing. Disposal in landfills is decreasing (from 60.9 to 55.5% in 1996). Waste disposal by combustion is also increasing. This is primarily due to the increased efficiencies of the new incinerators and their ability for the removal of particulates and harmful gases. Plastics are a small but a significant component of the waste stream. It is encouraging to note that the amount of plastics being recycled has grown significantly. In 1997, about 317 million kg of high density polyethylene (HDPE) bottles and 294 million kg of polyethylene terephthalate (PET) bottles were recycled. Recycling of durable goods, such as automotive parts, carpets, electronic and appliance housings and parts are being explored. Environmental compatibility and recyclability are being considered during the designing of new parts. Life cycle analyses and management are also being studied as tools for decision making.
Notes:
- General review of plastics recycling in the US.
- some good data, but potentially out of date (data from early to mid 1990s)
Optimal Recycling of Waste Materials in a Plastic Extrusion Production Process[edit | edit source]
S.P. Ladamy, K.C. So, "Optimal Recycling of Waste Materials in a Plastic Extrusion Production Process". European Journal of Operational Research, 79(1994), pg 13-24.
- Recycling process overview.
- Recyled plastic mixed with virgin material to retain engineering properties
- Less virgin material in plastic each cycle
- Authors attempt to determine optimal number of cycles of mixing reclaimed and virgin material
- Based on factors such as sale price, value of recovered waste material, raw material cost, production, etc.
- Numerical model developed to determine optimum cycling.
Relevance:
- Some useful insights into engineering properties of recycled plastics.
- Virgin material mixing may be utilized.
An efficient method of material recycling of municipal plastic waste[edit | edit source]
I. Fortelný, D. Michálková, and Z. Kruliš, "An efficient method of material recycling of municipal plastic waste," Polymer Degradation and Stability, vol. 85, no. 3, pp. 975-979, Sep. 2004.
- goal is to find a compatibiliser for PE/PP/PS to reduce the need for sorting
- tested mixes of 5% EMP, 5% SBS and 5% EPM/SBS and charted tensile strength
- adding 5% of EP(D)M/SBS and .5% of a stabiliser with proper mixing conditions leads to a mixture with toughness comparable w. virgin polyolefins
- EPM - ethylene-propylene-diene statistical terpolymer
- SBS - styrene-butadiene block copolymer
Plastic and Plastic-Composite Materials[edit | edit source]
Phase Structure and Properties of Poly(ethyleneterephthalate)/High-Density Polyethylene Based on Recycled Materials[edit | edit source]
Yong Lei et al., "Phase Structure and Properties of Poly(ethyleneterephthalate)/High-Density Polyethylene Based on Recyced Materials," Journal of Applied POly Science 113 (2009): 1710-1719.
- PET and PE combinations - less brittle, stiffer, better flowing, cool faster than HDPE so can be made faster
- Recycled PET - higher flexural strength, flexural modulus, tensile strength, tensile modulus compared to recycled HDPE
- Recycled HDPE - higher impact strength
- Mixing recycled PET and HDPE - almost linear changes in flexural strength, flexural modulus, tensile strength and tensile modulus between values found for PET 100% and HDPE 100%
- Impact strength at a minimum w. 50/50 blend of HDPE and PET because of incompatibility
- HDPE crystallinity increases when blended with PET
- PET crystallinity decreases w. addition of HDPE
- adding 2% PE-g-MA and 5% SEBS suppressed crystallinity in HDPE and PET, and improved impact strength
- adding .5% increased tensile modulus but lowered tensile and impact strength
Processing Technologies for poly(lactic acid)[edit | edit source]
Lim, L. -., Auras, R., and Rubino, M., 2008, "Processing Technologies for Poly(Lactic Acid)", Progress in Polymer Science, 33(8) pp. 820-852.
Abstract:
Poly(lactic acid) (PLA) is an aliphatic polyester made up of lactic acid (2-hydroxy propionic acid) building blocks. It is also a biodegradable and compostable thermoplastic derived from renewable plant sources, such as starch and sugar. Historically, the uses of PLA have been mainly limited to biomedical areas due to its bioabsorbable characteristics. Over the past decade, the discovery of new polymerization routes which allow the economical production of high molecular weight PLA, along with the elevated environmental awareness of the general public, have resulted in an expanded use of PLA for consumer goods and packaging applications. Because PLA is compostable and derived from renewable sources, it has been considered as one of the solutions to alleviate solid waste disposal problems and to lessen the dependence on petroleum-based plastics for packaging materials. Although PLA can be processed on standard converting equipment with minimal modifications, its unique material properties must be taken into consideration in order to optimize the conversion of PLA to molded parts, films, foams, and fibers. In this article, structural, thermal, crystallization, and rheological properties of PLA are reviewed in relation to its converting processes. Specific process technologies discussed are extrusion, injection molding, injection stretch blow molding, casting, blown film, thermoforming, foaming, blending, fiber spinning, and compounding.
Notes:
- Good resource for properties and conventional processing of PLA.
- effects of heat, extrusion on PLA properties - may affect recyclability.
Polylactic Acid Technology[edit | edit source]
R. E. Drumright, P. R. Gruber and D. E. Henton, "Polylactic Acid Technology," Advanced Materials, 12(23), pp. 1841-1846, 2000. Available online[1]
Abstract:
Polylactic acid is proving to be a viable alternative to petrochemical-based plastics for many applications. It is produced from renewable resources and is biodegradable, decomposing to give H2O, CO2, and humus, the black material in soil. In addition, it has unique physical properties that make it useful in diverse applications including paper coating, fibers, films, and packaging.
Notes:
- Polylactic acid (PLA) is a biopolymer made from starch sources (i.e. corn, beets).
- Has been used successfully with the RepRap machine.
- Biodegradable plastic means reduction in waste... if a domestic source could be obtained it may be a useful feedstock.
- This article provides basic review of PLA:
- production
- degradation
- properties
- applications
- treatment options (i.e. peroxide treatment to promote branching and therefore increase strength)
Plastics Processing Technology[edit | edit source]
Muccio, E.A., 1994, "Plastics Processing Technology", ASM International, Materials Park, OH, pp. 302.
- comprehensive review of plastics and processing technologies.
- 4th printing in 1999. Slightly outdated, but still useful for information on material properties and conventional processing practices.
- preview available on Google books.
Society of the Plastics Industry (SPI), Resin identification codes[edit | edit source]
- set of codes developed in 1988 to be applied to plastic objects to identify their composition
- allows for simplied sorting during the recycling process.
- system is used internationally.
- may help with plastic sorting for waste plastic extruder
See the SPI website for more information: available here
The American Chemical Council has also published a chart showing the appropriate SPI symbol and summarizing the properties and applications of each resin type. The chart is online here.
A kinetic model of polymer degradation during extrusion[edit | edit source]
E. G. El'darov, F. V. Mamedov, V. M. Gol'dberg, and G. E. Zaikov, "A kinetic model of polymer degradation during extrusion," Polymer Degradation and Stability, vol. 51, no. 3, pp. 271-279, Mar. 1996.
- focuses on PE
- processing degradation caused by formation of alkyl R radicals that interact w. oxygen to make peroxide R02.
- molecular weight decreases because peroxide causes bonds in the macromolecular bonds to break
- includes equations that determine possible changes of molecular weight and the amount of absorbed oxygen * breakage or changes in the amount of crosslinking is not the cause of the of the changes in molecular weight, caused by the oxidation reaction
- at low temps molecular weight decreases bc. of mechanically initiated breaks, medium temps (up to 190 C) molecular weight increases, between 210 - 220 C macromolecular weight stable and above 220 C macromolecular weight decreases