摘要:

AbstractThe economical incitement is larger for recycling of expensive engineering materials than for packaging plastics. It should, however, be possible also for municipal waste industry to profit from recycling of packaging waste. At present, municipal waste plants already sell sorted plastics fractions on the order basis. The degree of mixing of these plastic fractions is the key question to be solved in order to obtain a high‐quality product. The value of recycled HDPE fraction is lowered if it contains impurities of other polymers, e.g. PP, PS or PET because such impurities cause embrittlement. An addition of an impact modifier to contaminated HDPE was analyzed with respect to changes in morphology and mechanical properties. Oxidative stability of the polymer matrix decreased as a result of recycling, indicating decomposition of heat stabilizers, as shown for polyamide 66. The relation between expensive/cheap recycled plastics is discussed based on their long‐term propert

ISSN:1022-1360    

DOI:10.1002/masy.19981350103

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractThermal and catalytic degradation of plastic polymers, polyethylene and polypropylene to fuel oil were carried out in batch operations. The catalysts employed were acid silica‐alumina (SA‐1, SA‐2) and zeolite ZSM‐5, and non‐acidic mesoporous silica FSM (folded sheet material). The yields of product gas, liquid and residues, recovery rate of liquid products, and boiling point ranges of liquid products due to degradation were compared with those of non‐catalytic thermal degradation. Both the effect of catalytic contact mode and of catalyst type on the degradation were studied.In liquid‐phase degradation of PP over SA‐1, liquid hydrocarbon products were obtained in a yield of 69 wt.‐% with a boiling point range 36‐270°C, equivalent to the boiling point of normal paraffins C6 ‐ C15. The liquid products from catalytic degradation have a carbon‐number distribution very similar to commercial motor gasoline. In vapor‐phase contact, the yield of liquid products was much lower (54%) and the rate of liquid recovery was much slower.With FSM, the initial rate of degradation of PP and PE to liquid products was as fast as that over acid catalyst SA‐1, but the yield of liquid products was higher. The liquid products from catalytic degradation over FSM have a carbon‐number distribution similar to kerosene and diesel oil. In repeated use, SA‐1 deactivated very rapidly due to coke deposition on the catalyst, whereas FSM deactivated much more slowly. These findings suggest that mesopores surrounded by the silica sheet may act as reservoir for radical species, which accelerate

ISSN:1022-1360    

DOI:10.1002/masy.19981350104

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractCo‐pyrolysis of coal with waste polymers in a stationary quartz reactor was performed. Mass balance of the process was evaluated and properties of products were characterized. The main product (solid carbonaceous residue) exhibits low ash and sulfur contents and, from the point of view of application, satisfactory surface properties. Therefore, the solid residue is suitable as a smokeless fuel or as an industrial sorbent. The by‐products were tar and gas. The tar may be used as a source of chemicals or a low‐sulfur heating oil, the gas was highly calorific, therefore it may serve as a heating gas for energetical pur

ISSN:1022-1360    

DOI:10.1002/masy.19981350105

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractThe decrosslinking of thermosetting reaction injection molded (RIM) polyurethane‐urea products with the smallest amounts of glycols was studied. The effects of the reaction conditions on the properties of liquid oligomers were determined. Successful scale‐up studies and utilization of the resulting liquid oligomers for preparation of RIM products, coatings and adhesives are descri

ISSN:1022-1360    

DOI:10.1002/masy.19981350106

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractFor chemical recycling of plastic refuses a cascade of cycled‐spheres reactors has been developed combining separation and decomposition of polymer mixtures by stepwise pyrolysis at moderate temperatures. In low‐temperature pyrolysis, mixtures of poly(vinyl chloride), polystyrene and polyethylene or polystyrene, polyamide 6 and polyethylene have been separated into hydrogen chloride, styrene and polyamide 6 and aliphatic compounds from polyethylene decomposition. Compared with the low‐temperature pyrolysis of the single components, some interactions between the polymers are found when pyrolyzing mixtures. Some mechanistic aspects of these interactions are disc

ISSN:1022-1360    

DOI:10.1002/masy.19981350107

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

ISSN:1022-1360    

DOI:10.1002/masy.19981350108

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractMixed plastics from junked autos were homogenized by milling or extrusion, modified by addition of low‐molecular‐weight low‐melt‐viscosity polymers, and processed by compression or injection molding. Properties were comparable with high‐density polyethylene and common building panel

ISSN:1022-1360    

DOI:10.1002/masy.19981350109

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

摘要:

AbstractPlastics pyrolysis is based on thermal and sometimes catalytic breakdown of the polymer structure. The target product may be monomer (from PMMA, PTFE, PS), oil fractions ranging from petrol (C5‐C10) and kerosene (C10‐C15) to waxy fractions (≥C20), aromatics, synthesis raw materials formed by hydrogenation or synthesis gas (H2, CO). The desired product determines the operating conditions required and hence the technology used. A survey is given of laboratory, pilot and industrial scale reactors, pyrolytic extruders, stirred tanks and single‐ or double‐bed fluidized systems. Moreover, the use of plastics in oil refinery‐based processes, such as fluid catalytic cracking, hydrocracking, viscosity breaking and delayed coking, and also (coal‐derived) hydrogenation and gasification are briefly covered. The product distribution in a pyrolysis process has to be derived experimentally, with the operating temperature, heating rate, catalytic effects, residence time of feed material and reaction products, reaction pressure, possible supply of reactive gases (such as oxygen, hydrogen) and, of course, the chemical constitution and structure of the original plastics as major factors. Pyrolysis involves the breaking of chemical bonds and is normally endothermic. The required heat of reaction can be supplied indirectly through the reactor walls, by a circulating heat carrier, which may be the polymer content of the reactor or the sand in a dual fluid‐bed system, or by partial oxidation. The reactor technology is generally determined by the temperature level required, heating method, necessary residence time and possibly the presence of a catalyst, required to rearrange linear structures to high‐octane‐number branched ones, to eliminate heteroatoms (Cl, N, O, S), etc. Some potential operating problems are addressed in an EU‐funded project with acronym Cycleplast, a joint project of five teams from Central and Western Europe, the aims of which

ISSN:1022-1360    

DOI:10.1002/masy.19981350110

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

ISSN:1022-1360    

DOI:10.1002/masy.19981350111

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY

ISSN:1022-1360    

DOI:10.1002/masy.19981350112

出版商:WILEY‐VCH Verlag GmbH&Co. KGaA    

年代:1998

数据来源: WILEY