Tibor Czvikovszky

Polymer recycling: potential application of radiation technology

Abstract Management of solid waste is an important problem, which is becoming progressively worse as a byproduct of continuing economic growth and development. Polymeric materials (plastics and rubbers) comprise a steadily increasing proportion of the municipal and industrial waste going into landfill. Development of technologies for reducing polymeric waste, which are acceptable from the environmental standpoint, and which are cost-effective, has proven to be a difficult challenge due to complexities inherent in the reuse of polymers. Establishing optimal processes for the reuse/recycling of polymeric materials thus remains a worldwide challenge as we enter the new century. Due to the ability of ionizing radiation to alter the structure and properties of bulk polymeric materials, and the fact that it is applicable to essentially all polymer types, irradiation holds promise for impacting the polymer waste problem. The three main possibilities for use of radiation in this application are: (1) enhancing the mechanical properties and performance of recovered materials or material blends, principally through crosslinking, or through surface modification of different phases being combined; (2) treatment causing or enhancing the decomposition of polymers, particularly through chain scission, leading to recovery of either low molecular weight mixtures, or powders, for use as chemical feedstocks or additives; (3) production of advanced polymeric materials designed for environmental compatibility. This paper provides an overview of the polymer recycling problem, describes the major technological obstacles to the implementation of recycling technologies, and outlines some of the approaches being taken. A review of radiation-based recycling research is then provided, followed by a discussion of future directions where irradiation may be relevant to the problems currently inhibiting the widespread recycling of polymeric materials.

Electron-beam processing of wood fiber reinforced polypropylene

A reactive extrusion procedure has been developed for wood fiber reinforced thermoplastic composites, applying a small amount of reactive additive that compatibilizes the synthetic and natural polymer components, with a subsequent Electron Beam treatment which is a productive method of creating active sites on both matrix polymer and fibrous reinforcement. Wood fiber and polypropylene (PP) bound together through reactive additive results in a composite which has not only a high modulus of elasticity, but also significantly higher flexural and tensile strength and improved thermal tolerance over the conventional wood fiber-PP blends, and over the PP itself.

Expected and unexpected achievements and trends in radiation processing of polymers

Abstract The last four decades produced exponential development in the polymer processing. Radiation processing—initiated also about 40 years ago—yielded a similar pathway of development in the beginning, mostly in the radiation crosslinking of polymers and in the radiation sterilization of polymer products. There are some unexpected results in the developments of the radiation chemistry of polymers utilized well in the polymer processing today. The most dynamical developments of the microelectronics in our days are based on the efficient utilization of radiation-crosslinkable negative photoresist polymers and the radiation degradable positive photoresist polymers. Rapid prototyping and rapid tooling are indispensable methods in the continuously renewing manufacturing technologies of metal and plastic parts for almost all the industrial branches. Polymer composite manufacturing is also profited in many ways from the experiences of radiation technology. Compatibilization through radiation-reactive monomers and oligomers is attacking two great fields of the future polymer processing. Recycling of commingled polymer wastes, and manufacturing new type of alloys of different synthetic as well as natural polymers are requiring well-engineered interface, which can be achieved by radiation processing in a technically feasible and economically viable way.

Effect of nanotube content on mechanical properties of basalt fibre reinforced polyamide 6

Abstract In this study, 30 mass-% basalt fibre and 0·5–2 mass-% multiwall carbon nanotube (MWCNT) reinforced polyamide 6 hybrid systems were prepared by extrusion and injection moulding. The effect of nanotube content on the mechanical properties was investigated by tensile and flexural tests. The results showed that the combination of macroscopic and nanosized reinforcements improved the mechanical properties significantly, and synergetic effects can also be observed. Good dispersion of the MWCNT was proven by transmission and scanning electron microscopy.

EB processing of braided carbon fibre composite profiles

Abstract A new type of carbon fibre reinforced composite profile has been developed by applying braiding, a well-known process of textile technology. Pipe and hollow profile composite products can be manufactured this way by using electron beam cross-linking. The fabric-like braided reinforcing structure was manufactured out of carbon fibre roving. A vinylester type epoxy derivative has been used as matrix material for the composite. The EB irradiation of the impregnated system resulted in better mechanical properties than conventional chemical curing. Besides the static mechanical testing, an advanced dynamical testing method, the falling weight crash test has been successfully tried out on those braided composite systems, to be applied later in the transport industry.

The Effect of Pre-Electron Beam Irradiation of HDPE on the Thermal and Mechanical Properties of HDPE/PET Blends

The effect of electron beam (EB) irradiation of high density polyethylene (HDPE) on polyethylene-terephthalate (PET)/HDPE blends has been investigated. The HDPE component was radiation treated before the blend was melt mixed. Although the radiation treatment of HDPE component with 50-200 kGy caused some decrease in the tensile strength and elasticity modulus, the maximum tensile elongation of the blend showed a significant increase (+40%) at optimum dose (100 kGy). The DSC results and the scanning electron microscope images of the fracture surfaces also showed the benefit of a 100 kGy EB-dose in the connection the otherwise thermodynamically incompatible part of the blend.

The Influence of the Extrusion Temperature on the Mechanical Properties of MMT Filled PA 6 Composite

Effects of varying extrusion temperatures on the mechanical properties of polyamide 6 (PA 6) matrix montmorillonite (MMT) filled composites were investigated in this paper. Five different temperature programs were used for producing composites with 1 wt.% nanoparticles content. The mechanical properties were evaluated by tensile and flexural tests and SEM pictures were taken from the fracture surfaces. X-ray diffraction patterns were also measured to obtain some information about the structures of the materials. The results showed that the lower extrusion temperatures resulted in better mechanical properties of the composite.