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The paper presents the results of research on the possibility of using as plasticizers of rubber compounds the heavy fractions of pyrolytic oil obtained in the industrial process of pyrolysis of car tyres. The content of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in the obtained pyrolytic plasticizers was determined. Compounds and vulcanizates of styrene-butadiene rubber (SBR) containing the above plasticizers as well as commercial petroleum derivatives’ plasticizers were prepared for comparative purposes. The basic properties of compounds and vulcanizates containing pyrolytic plasticizers were investigated. The research showed that one fraction of pyrolysis oil meet the requirements of the permitted content of PAHs. SBR blends and vulcanizates have similar properties as in the case of commercial plasticizers.

In the pilot plant for pyrolysis of whole tyres for passenger cars and vans we received a liquid product, hydrocarbon fraction known as pyrolytic oil, two solid products, i.e. pyrolytic carbon, scrap metal cord and gaseous mixture of hydrocarbons. The main goal of the research was to determine susceptibility of the obtained pyrolytic oils to hydrorefining. The analysis showed that hydrorefining process, carried out in the presence of commercial catalysts, allows for much improvement of its characteristics. However, it is necessary to apply relatively hard process conditions: temperature of at least 360 °C and hydrogen pressure of about 5 MPa. Then the product is desulphurised down to the sulphur content of less than 0.2% by weight and the unsaturated hydrocarbons are partially hydrogenated, which is characterised by the decrease of bromine number to less than 20 g Br2/100 g. As a result of high content of aromatic hydrocarbons, in respect of relatively high sulphur content, high density and low cetane index (lower than 35), even after hydrorefining process, pyrolytic oil can only be used as a component of fuel oils.

The effective synthesis of citropin–polymer conjugates was described in this paper. The obtained biodegradable polymeric matrices and polymeric conjugates were characterized using 1 H or 13 C NMR and Fourier transform infrared spectroscopies, gel permeation chromatography and scanning electron microscopy. Toxicity of polymers was evaluated with bacterial luminescence test and two protozoan assays. The in vitro release study of citropin from the obtained conjugates was investigated. The preliminary results of antimicrobial activity of the obtained macromolecular conjugates against Bacillus anthracis , Enterococcus hirae and Staphylococcus aureus were also discussed. The peptide had a high level of antimicrobial activity during 3–5 weeks of the degradation process. The development of biodegradable citropin systems should be of a great interest in the delivery systems of antimicrobial agents.

The past decade has seen growing interest in the investigation of peptides with antimicrobial activity (AMPs). One approach utilized in infection control is incorporation of antimicrobial agents conjugated with the polymers. This review presents the recent developments on polymeric AMP carriers and their potential applications in the biomedical and pharmaceutical fields.

The influence of engine oil absorption on the dynamic properties of NR, NBR and their mixtures containing 50 or 75 phr of NBR modified various amounts of carbon black as filler has been investigated. It was determined that a slight absorption of oil by the NBR vulcanizates leads to an increase in the space phase angles but a decrease in the value of the module G * . A high degree of absorption of oil observed in the case of NR vulcanizates results however in a significant decrease in the δ angle as well as the G * module. The dynamic properties of the NR/NBR mixture vulcanizates did not constitute a combination, but differ in a crucial manner from the properties of the individual vulcanizates. The influence of oil absorption on the properties the tested vulcanizates depends on both the filler (carbon black) as well as the NBR content in the system. However, in the case of the 25/75 NR/NBR vulcanizates with 50 phr of the filling carbon black, a change in the values of space phase angle and group module was not observed.

The effects of carbon black amount (up to 70 phr) and NBR content in NR/NBR vulcanizates (NBR - nitrile-butadiene rubber, NR - natural rubber) on their mechanical properties and resistance to motor oil were investigated. As well the vulcanizates of individual rubbers were tested. All systems were characterized using vulcametric method (Table 1). As a result of equilibrium swelling of NR vulcanizates with oil, mechanical properties drastically deteriorated and this deterioration was directly proportional to the degree of oil absorption, lowering with carbon black content (Table 2). What concerns oil-extended NBR vulcanizates neither weight gain nor increase in volume of the samples were observed in the whole range of carbon black content. However, small changes in hardness and strength (more visible when vulcanizates contained smaller amounts of filler) show that limited oil absorption by NBR vulcanizates occurs (balanced with elution of the system components) (Table 3). Swelling degree of NR/NBR blends vulcanizates depend both on NBR and carbon black contents. Swelling degree of the systems containing 50 phr of NBR and up to 30 phr of carbon black reached still rather high values (Table 4). For vulcanizates containing 50-70 phr of carbon black it was four times lower than in case of NR samples with the same carbon black content while tensile strength decreased only 24 %. NR/NBR vulcanizates containing 75 phr of NBR and 30-70 phr of carbon black show good resistance to oil (Table 5). Mechanical properties of these vulcanizates after swelling are practically the same as before. The observed effect of vulcanizate composition on the properties tested was interpreted on the basis of morphology investigations by SEM method (Fig. 1 and 2).

Rubber elements, which usually form a major part of different isolators of vibrations, are generally easily swelled by oils, greases, or fuels. This leads to meaningful changes of their mechanical characteristics and shortening of durability of rubber components in service. The influence of the semisynthetic motor oil on mechanical and, particularly, dynamic properties of swelled vulcanizates of the polar diene rubber, chloroprene (CR) and acrylonitrile-butadiene (NBR), is estimated in this article. These elastomers, as is widely known, are resistant to the mineral oils absorption. However, our investigations showed that even a small degree of swelling of the vulcanizates causes decrease of their mechanical properties and considerable changes of the dynamic characteristics of the samples. The obtained results have shown the need to take into account the environment in which isolators of vibrations and dampers have worked, while designing the suitable composition of rubber compounds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

In this study, new composite bisphosphonate delivery systems were obtained from polyurethanes (PUs) and nanocrystalline hydroxyapatite (HA). The biodegradable PUs were first synthesized from poly(ε-caprolactone) diols (PCL diols), poly(ethylene adipate) diol, 1,6-hexamethylene diisocyanate, 1,4-butanediol and HA. Moreover, the PCL diols were synthesized by the ring-opening polymerization catalysed by the lipase from Candida antarctica. Next, composite drug delivery systems for clodronate were prepared. The mechanical properties of the obtained biomaterials were determined. The cytotoxicity of the synthesized polymers was tested. The preliminary results show that the obtained composites are perspective biomaterials and they can be potentially applied in the technology of implantation drug delivery systems.

Oligo(trimethylene carbonate) and oligo(neopentyl carbonate) diols were obtained by the polymerisation of corresponding six-membered cyclic carbonates in the presence of catalysts prepared in the reaction of water with diethylzinc or triethylaluminium. Their structures were proven by means of MALDI TOF and NMR spectroscopic studies. The oligocarbonate diols were reacted with 4,4′-methylenebis(phenyl isocyanate) in the presence of 1,4-butanediol as the chain extender to obtain polyurethane elastomers. The physical and mechanical properties and hydrolytic stability of novel polyurethane elastomers were compared with those of conventional materials based on polyester type soft segments.

Studies on the possibility of the application of the solid-state postpolycondensation (SSP) process to increase the average molecular weight of bisphenol A-based polycarbonate (PBC) were carried out. The thermally stable PBC with a very high molecular weight reaching about 50,000 g/mol was obtained by the applied SSP technique. Some factors influencing the effectiveness of the SSP process were initially examined: the mode of preparation (crystallization) of the PBC prepolymer, condensation temperature and time, and the vacuum applied in the reaction vessel. It was found that the superior yield of the high molecular weight PBC was obtained by the employing as high as possible values of the parameters taken into consideration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2165–2171, 2000

A series of polyurethanes (PURs) were prepared by metal-free method, containing polycaprolactone (PCL) as the soft segment with molecular weights of 1600, 2400 and 2600. PCL was obtained by the ring-opening polymerization of ε- caprolactone in the presence L-alanine and L-phenyloalanine. The structure of synthesized oligoesters and PURs were spectroscopically confirmed. The molecular weights, mechanical and thermal properties of the obtained materials were reported.