Treatment of Plastics

There are at present only a few commercial applications of ultrasound in the plastics industry. The best knovm is probably the welding of thermoplastics, a process which now lends itself readily to automation. In common with the welding of metals, the ultrasonic welding of plastics is primarily a hot stage. In the process ultrasound is applied to two layers of plastic, heat is generated at the interface causing the material 

Treatment of polymers Power ultrasound in polymer technology Treatment of plastics 

Enhanced radical production Reduction in viscosity in molding 

Provided the ultrasonic heat is applied selectively at the interface only, it vdll cause minimum distortion and degradation of the material. Obviously in order that a good weld may be obtained, the plastic must have characteristics which make it suitable for welding. These include  

a low thermal conductivity to facilitate local build-up of heat  

---

LCAs on treatment of plastics waste basically calculate the resultant of two parts ... 

For treatment of plastics packaging waste, many technologies are available. They basically can be divided into the following classes ... 

Table 5 Tentative cost comparison of treatment of plastics waste (in /ton) ...

As mentioned before, additives do not come out as contributing to life cycle impacts in any of the 110 case studies reviewed. From the above, it is clear that a straightforward LCA case study using a standard LCI database would indeed not show additives, because they are not present in these databases. The fact that the plastics data are aggregate data masks any omissions, implying it is possible that case study performers were unaware of it. For example the studies on (waste treatment) of plastic packaging [6-12], plastic cup studies [13,14] and some studies on automotive parts [15, 16] do not mention additives at all. 

D. Brewis (ed.), Surface Analysis and Pre-treatment of Plastics Metals , Applied Science Publishers, London, 1982. 

Thermal and catalytic treatments of plastic wastes present meaningful differences. In terms of mechanism, thermal degradation proceeds according to a radical chain reaction... 

A more interesting approach for co-processing is the conventional treatment of plastic with a heavy petroleum fraction blend in a refinery unit. The main advantage of this coprocessing method is that it utilizes existing processes within a refinery complex, resulting in reduced capital costs. Little research has focused on the co-processing of plastics with a feedstock of a refinery unit. Studies have been carried out with different plastics and refinery feeds. 

The gasiflcation process is particularly effective for the treatment of plastics. The reducing atmosphere and the presence of hydrogen leads to an instant breakdown of the molecular structure of the plastic to form CO and H2 while any halogen compounds are released for capture in the gas clean-up system [72]. 

The methods that will be dealt with here are those used to obtain hydrocarbon vapours from this first phase. The treatment of plastic wastes of all sorts by pyrolysis, being still in its early stages, workers keeping practised procedures confidential, and often protects them by patents. As a consequence, this chapter deals exhaustively only with the procedures that have been personally tested and developed by the author. The general principle of polyolefin waste pyrolysis consists of heating plastic materials in isolation to a sufficient temperature such that the polymers decompose into small hydrocarbon molecules. 

This book is intended to be useful to anyone working with plastic foams (cellular plastics), and to a lesser extent, elastomeric foams. The emphasis is on practical, rather than theoretical aspects. The books should prove helpful to materials engineers, chemists, chemical engineers, sales personnel. It may also find use as a textbook or reference source in materials engineering courses. The book is a comprehensive technical treatment of plastic foams and covers information not available in any other single source. 

CZVIKOVSZKY T., Recycling and treatment of plastics waste, In Radiation technology for conservation of the environment, IAEA-TECDOC-1023, IAEA, Vienna, 1998. 

In addition to gasification, other oxidative treatments of plastic and rubber wastes, excluding total combustion, are described in this chapter. These methods, although relatively unknown, may be of great interest in the future for the chemical degradation of polymeric wastes. 

The polymer molecules start to break down in the presence of catalysts at considerably lower temperatures than in thermal decomposition. A significant catalytic conversion of polyolefins into volatile products has been detected at temperatures as low as 200 °C, compared with the value of 400 °C which is necessary in the thermal degradation of PE and PP to observe the formation of the first gases. As a consequence, catalytic treatments of plastic materials are usually carried out at low temperatures, in contrast with the range of 500-800 °C, typical for thermal cracking and pyrolysis. 

Kaplan, S. L., and Rose, P. W., Plasma Treatment of Plastics to Enhance Adhesion An Overview, Technical Paper, Plasma Sci., Inc. 

While the binding of fibronectin appears to be a critical feature in the response of cells to many man-made materials, recent studies have shown that treatment of surfaces with other extracellular matrix components, such as laminin and type IV collagen (60), can greatly alter the biological properties of plastics. Treatment of plastic with a biomatrix derived from a basement membrane tumor can alter the morphology and differentiated state of several cell types (60). Hence, the biological properties of polymeric materials are dependent on the type of extracellular atrix molecule absorbed more than the chemical nature of the polymer itself. 

Plasma-Chemical Treatment of Plastics, Rubber Materials, and Special Polymer Films... 

The present chapter is divided into four parts. After a review of elasticity theory, we shall discuss simple elastic behaviour of single crystals of ice, then examine the relaxation processes which take place for periodically varying stresses and finally take up a brief treatment of plastic deformation, creep and related topics. 

Surface treatment of plastic containers is sometimes used to improve barrier properties, or to enhance printability or label adhesion. 

The cost of the treatment of plastic waste depends on the recycling rate of the material. It goes from 0.32 kg for a recycling rate of 10% to 0.80 kg at a recycling rate of 50% (according to Neil Mayne and Herbert Fisch, APME, Brassels, February 2002). 

In the treatment of plastics, the free radicals generated in the reaction chemically modify (ionize) the surface of the TPO thus allowing the color coat to attach itself to the polar TPO surface. The rest of the process is the same as in the Baseline above. QC method TPO surface 1/ FTIR 2/ surface tension Painted part 1/ cross-hatch adhesion 2/other tests. 

Pyrolysis is the treatment of plastic waste in the presence of heat under controlled temperatures without catalysts. The pyrolysis process is an advanced conversion technology, in which the hydrocarbon content of the waste is converted into a clean, high calorific value gas from a wide variety of plastic waste. The produced gas can be utilized in gas engines, electricity generation, or in boiler applications. 

M.L. Mastellone, Thermal treatments of plastic wastes by means of fluidized bed reactors. Ph.D. Thesis, Department of Chemical Engineering, Second University of Naples, Italy, 1999... 

Gezas, S. I. Decoration Treatment of Plastic Things. Chemistry, (Russ) (1978). 

B. Rotrekl, K. Hudecek, J. Komarek, and J. Stanek, Surface Treatment of Plastics, Khimiya... 

---