INTRODUCTION Jta
Techniques for selection and recycling of post-consumer plastics are closely related to the characteristics of plastic containers consumption, which are extremely diversified according to the geographical areas and the relevant law regulations governing activities in this sector. In each area, socio-economic and legislative features as a whole determine the first stage of the recycling process, that is collection. This, in turn, influences the layout of the recycling plant which aims at the...
RESULTS AND DISCUSSION Processing
When mixed plastics waste is processed, one ofthe main problems is to find the best compromise between homogenization and degradation. In the waste material, there are polymers with different melting points and different thermal stability. Especially, PVC and PET are very difficult to process together, because the melting point of PET is over 250oC, and at this temperature PVC is easily decomposed forming HCl and chary residues. Therefore, the optimal processing Figure 1. The modulus and impact...
Mechanical behavior of HDPELDPE blends
The mechanical properties of blends of virgin HDPE and LDPE and plastic wastes are below those expected on the basis of an additive rule.22-29 In Figure 5 Figure 5. Polar representation of mechanical behavior of HDPE LDPE system containing either virgin polymers or composition from urban wastes. Figure 5. Polar representation of mechanical behavior of HDPE LDPE system containing either virgin polymers or composition from urban wastes. a polar representation was plotted showing the mechanical...
Quality of the raw materials
Virgin PET had an intrinsic viscosity of 0.78 dl g and was crystallized and solid state-polycondensed upgraded by the chemical manufacturer. PET reground flakes came from an unknown PET source. The flakes consisted of 100 PET before the reground bottle flakes went through a separation and clean-up process. The flakes were not regranulated since this step involves separate machinery and would add to the cost of the reground polymer material. The intrinsic viscosity was 0.03 to 0.05 dl g lower...
Mechanical Properties
The mechanical properties of all the investigated materials are reported in Figures 2-5 as a function of the mixed plastics waste concentration. The experimental results are reported in dimensionless form, i.e., the value relative to each blend is divided by the corresponding value of the unblended matrix. These latter values are reported in Table 2 for three matrices. As expected, all the mechanical properties, except for the elastic modulus, decay on increasing the MPW content. The extent of...
Microstructural aspects of HDPELDPE blends
Figures 9 to 10 show micrographs of the microtomed sections from injection molded bars. The different microstructure of HDPE LDPE blends, having different compositions, are shown Figure 9 . In fact, these thin sections taken in the parallel flow direction inside the cavity of a mold and near the gate, show differences in Figure 13. Micrographs of 85 15 left and 15 85 right HDPE LDPE ratio with 1 LMWPE. Figure 13. Micrographs of 85 15 left and 15 85 right HDPE LDPE ratio with 1 LMWPE. Figure 14....
INTRODUCTION Uyl
Problems connected with recycling of polymeric materials arise mainly from the heterogeneous nature of plastics waste and from degradation of polymers occuring either during their processing or their lifetime. As for the first point, important only when mixtures of plastics have to be recycled, it is well established that a strong incompatibility is typical for polymers usually found in plastics wastes PE, PET, PVC, PS, PP . This incompatibility gives rise to materials which are very difficult...
Drying of PET resin and PET flakes Figure
The drying of a virgin PET resin and reground PET flakes at temperature levels of 160-180oC to below 0.005 moisture content is essential for the production of amorphous multilayer polyester bottles. Polyester is an effective desiccant. The water absorption depends on a relative humidity, residence time, temperature, and dimension of the flakes. When flakes containing moisture are heated up to the melting temperature, hydrolytic degradation occurs lowering a viscosity ofthe melt that results in...
Direct Reuse
Over 50 of the PET film produced in the world is used as a photographic filmbase. The manufacturers of these materials, mainly Agfa-Gevaert, Eastman Kodak, du Pont de Nemours, Fuji, Minnesota Mining amp Manufacturing, and Konishiroku have long been interested in PET film recovery. An important motivation for the efforts made by these companies is the fact that photographic films are usually coated with one or more layers containing some amount of rather expensive silver derivatives, which have...
References
1 F. P. Boettcher, ACS Polymer Preprints, 32 2 , 114 1991 . 2. W. De Winter, Die Makromol. Chem., Macromolecular Symposia No. 57, 253 1992 . 3. Anon., Plastics Bulletin, 174, 6 Jan-1992 . 4. N. Basta et al., Chem. Eng., 97, 37 Nov-1990 . 5. Brit. Pat. 1.476.539 1977 to Barber-Colman Co. 6. Anon., Manufacturing Chemist, 66, Mar-1987 . 7. L. Hellemans, R. De Saedeleer, and J. Verheijen, US Pat. 4,008,048 1977 to Agfa-Gevaert. L. Jeurissen and F. De Smedt, Brit. Pat. 1,486,409 1977 to...
Disposal Of Residuals
An important financial element in recycling is residue disposal, whose costs are part of the overall economics of the recovery operation. Four general methods have been advanced for commercial utilization of the light fraction landfill, polymer-enriched fractions, structural materials, and fuels. It is unlikely that any revenue could be generated by landfill, since the non-metallic residue is voluminous, compressible, and lacks the properties desirable in hard-core. Current technology cannot...
HDPEheavy fraction blend
The HDPE heavy fraction blend, 75 25 was examined to evaluate a possibility of reusing of a heavy fraction as a filler of HDPE to obtain extrudates with appropriate rigidity. As indicated before, the heavy fraction was first ground to particles of about 100 m and then blended with HDPE pellets in a double-screw extruder at 180oC. At this temperature, all the components PVC, PET, nylons, crosslinked polymers, etc. are still solid in the molten HDPE. Morphological observation by SEM shows that...
Michael E Henstock and Klaus Seidl
The University of Nottingham, Nottingham NG7 2RD, England BMW, Section EG-554, M nchen, Germany In market economies recovery operations are judged on financial criteria. Thus, whether or not a discarded waste is exploited for the materials it contains depends, among other things, on the technical ease of recovery of a saleable secondary product. Since industry must also consider the environmentally-sound disposal of its residuals the ease of residuals disposal is financially important.1
CONCLUSIONS Obe
Blends of polyethylene with mixed plastics waste, up to 50-75 , can be extruded without significant difficulties and accelerated degradation of the PVC component. The mechanical properties depend on the structure of the polyethylene matrix, but, in general, are very similar to those of the matrix up to a MPW content of about 25-50 . The elongation at break rapidly decreases even at low MPW content however, in many applications this characteristic is not very important and the values recorded...
R O
Another approach consists of mixing small amounts of biodegradable polymers, e.g., polysaccharides, with a regular polymer e.g., a polyolefin , in order to make the end-product destroyable as well. Examples of polysaccharides poly-ethylene have been commercialized.38 Mixtures of starch with other polymers,40 including PET, have been studied,34 but no commercialization of the latter mixture is known so far. The fact, however, that the starch additive is only needed in small amounts, which hardly...
REFERENCES Wfs
1. M. J. Curry, Secondary Reclamation of Plastic Wastes, Vol. I and II, Technomic Pub., 1987 . 2. Proceedings of the Melting, Recycling Plas I, Technomic Pub., 1986 . 3. Ibid, Recycling Plas II, Technomic Pub., 1987 . 4. Ibid, Recycling Plas III, Technomic Pub., 1988 . 5. Ibid, Recycling Plas IV, Technomic Pub., 1989 . 6. Ibid, Recycling Plas V, Technomic Pub., 1990 . 7. R. Leaversuch, Modern Plast., 4 1990 . 8. Proceeding of the Meeting, Plastics Recycling-88, SPE Scandinavian, Copenhagen 1988...
Tpo Based Materials
Thermoplastic Elastomers TPE are classes of heterophasic polymers, characterized by thermo-reversible interaction among the polymeric chains. The new polymeric materials that are considered to produce easy recyclable automotive systems, can be defined as a sort of a new generation of Olefinic Thermoplastic Elastomers TPO , belonging to a broad family of polyolefinic alloys that can now be produced directly during the polymerization phase. These completely new materials, resulting from advanced...
Microseparation
Microseparation is a method by which a suspension medium is used to separate plastics with density higher or lower than the suspension medium. For example, water can be used as medium to separate PE from PVC or PET. In this case special tanks are used in which various types of plastic flakes are mixed with water and then given a sufficient time to position themselves in the most suitable way according to their density. Materials are subsequently extracted separately from the top or bottom. This...
INTRODUCTION Ijt
Recycling of mixed plastics waste is not new. The first industrial applications in Japan date from 1973.1 It is well known that it is possible to manufacture rods, stakes, bars, boards, plates, etc. from mixed plastics waste but the mechanical properties of these products are inferior. The recycled products cannot compete with virgin plastic materials, and therefore they have to find their market in areas dominated by cheap materials like wood and concrete. Moreover, the market of park benches,...
Reuse After Modification
Similar to the method described under direct re-use, in which PET-flakes are added during the esterification process, PET-polymer is broken down into low-molecular, low-viscous fractions. Such method could already be viewed as a method of re-use after modification. Because the intermediate products are not separated at any moment of the process, the degree of purity of PET-scrap must be high. For PET-wastes having a higher degree of contamination, other technological processes are applied,...
Macroseparation
Separation of plastic fractions when waste materials are still in initial form continues to appear the most conveniently applicable system, considering the increasing possibilities of automation it offers. It is of little interest as long as separation is manual, but it becomes worth discussing when conducted by an automatic separation process which includes various systems employing detectors currently available in the market. The first detector was developed by Tecoplast in Casumaro,...
PRELIMINARY RESULTS Comparison of virgin and recycled HDPE
The plastic fuel tanks investigated are produced from Lupolen 4261A, supplied by BASF AG, Ludwigshafen. In Stage 1 of the trials the virgin HDPE was formed into injection-moulded test pieces using an Engel CC 80 injection moulding machine, and tested in a variety of mechanical tests. The tested samples were then successively reground and remoulded. The following mechanical properties were assessed, and the change in each property reported after 15 cycles Comparison of fluorinated and...