Some barriers to the use of materials recovered from municipal solid waste
Abstract Municipal solid waste (MSW) contains materials which could be put to good use, yet it continues to be discarded, which suggests that it contains little or nothing of value under current conditions. This paper discusses the technical reasons for the lack of commercial interest in recovering materials from MSW. After examining the nature of the salvage industry and trends in the use of materials, the paper considers the characteristics of secondary materials, the properties required of them, and the scope for increased salvage activity. The market prospects are described for waste paper, ferrous and non- ferrous scrap, glass and polymers.
Some observations on the recycling of plastics and rubber
Abstract After a discussion of the quantity and quality of plastic wastes of various origin, the different possibilities for recycling these wastes are critically reviewed. Closed-loop recycling of pure, well-defined wastes is a problem only in critical applications. The recycling of mixed wastes, on the other hand, gives rise to a number of technical and economic difficulties. Direct processing is difficult, because of the different melting behaviour and thermal stability of the various components, and moreover leads to polymer “alloys” with poor mechanical properties and marketing potential. Sorting processes still yield fractions of insufficient purity. Compatibilising additives are expensive and not very efficient. The future of recycling depends on the development of new markets for plastics with inferior properties and of processing methods to improve the properties of mixed plastics Pyrolysis and hydrolysis open a range of interesting developments, but their economic and technical feasibility remain to be proven. Incineration, biodegradation and tipping cannot be considered to be fully satisfactory disposal methods, and recycling should be encouraged wherever it is economically and technically feasible.
Einige mechanische Eigenschaften binärer Thermoplast‐Legierungen
Die Spannungs-Dehnungs-Diagramme beim Zugversuch von Mischungen von isotakitischem Polypropylen mit Polyathylen von hoher und niedriger Dichte und einem Athylen-Vinylacetat-Copolymerisat werden beschrieben. Fur die Klarung wurden Dehnungsversuche an Modell-Mischungen durchgefuhrt und die Ergebnisse mit Hilfe der Spannungskonzentrations-Theorie diskutiert. Die Modelle bestanden aus einem Prufstabchen von Polyathylen hoher Dichte mit einem kreisrunden Loch in der Mitte. — Das Loch wird gefullt mit einer zweiten Komponente. Genau wie bei Polymer-Legierungen entstand bei dem Dehnungsversuch ein zaher oder ein sproder Bruch, abhangig von der Art der zweiten Komponente. Gefunden wurde, das die Bruchdehnung mit abnehmendem Modul der dispersen Komponente und ebenfalls mit zunehmender Haftung zwischen beiden Komponenten steigt. 
 
 
 
Mechanical Properties of binary Alloys 
 
 
 
The stress-strain curves of blends of polypropylene and high and low density polyethylene and of polypropylene and an ethylene-vinylacetate copolymer are described. 
 
 
 
For the interpretation of these curves stress-strain measurements on model-blends and some results of the theorie of the stress-concentration are used. 
 
 
 
The model-blends were composed with high density polyethylene microtensile specimens wherein a cylindrical hole was filled with a second component. 
 
 
 
As with the extrusion blends the model-blends showed brittle or tough breaking depending on the kind of second component. We found that the elongation to break increased with decreasing E-modulus of the inclusion and with increasing adhesion between the two phases.