Marcin Włoch

Progress in non-isocyanate polyurethanes synthesized from cyclic carbonate intermediates and di- or polyamines in the context of structure–properties relationship and from an environmental point of view

Commercially, polyurethanes are produced by the reaction of diisocyanates, polyols (polyester or polyether) and low molecular weight chain extender. Toxicity, moisture sensitivity and phosgene-based synthesis of diisocyanates resulted in investigations focused on obtaining the non-isocyanate polyurethanes (NIPUs). This work presents the review of synthesis and structure–properties relationship of non-isocyanate polyurethanes obtained by reacting cyclic carbonated intermediates with diamines or polyamines. Moreover, the presented methods of NIPU synthesis were analysed from the environmental point of view. Described five-membered ring cyclic carbonate intermediates were obtained by carbonation of glycidyl ethers or thiol-ene coupling of unsaturated cyclic carbonate monomers and thiols. The special interest was put on the bio-based non-isocyanate polyurethanes, obtained from chemically modified bio-based substances, e.g. carbonated vegetable oils. The mechanical and thermal properties of NIPUs are affected by functionality, structure and molecular weight of cyclic carbonate intermediates and diamines or polyamines.

Selected biotrends in development of epoxy resins and their composites

Epoxy resins and their fibre or particulate composites are widely used in various industries, including building, naval, aircraft, automotive and aerospace. Modern polymer science and technology focus on the development of green polymers and composites. There are two major areas of interest in the case of epoxy resins: the development of bio-based resins and the production of composites with natural fibres. One of the most interesting challenges is developing fully bio-based composites: that is, epoxy resins based on renewable resources and natural fibres. This paper presents a review of literature on epoxy resins and hardeners based on renewable resources (especially vegetable oils) and epoxy composites with natural fibres. We also describe some of the effective methods of improving the mechanical properties of epoxy–natural fibres composites, including chemical modification of the fibre surface and the application of hybrid reinforcements.

Morphology and properties of recycled polyethylene/ground tyre rubber/thermoplastic poly(ester-urethane) blends

The growing amount of plastics waste produced every year resulted in development of mechanical and chemical recycling methods of polymers and their blends or composites. From the environmental point of view, the possibility of plastics waste reusing and recycling is desirable. In this study three polymer blends were obtained with using recycled polyethylene (RPE), ground tyre rubber (GTR) and thermoplastic poly(ester-urethane) (TPU). The reference samples, without TPU, were also made. The mass ratio of RPE to GTR was the same in each prepared materials. The morphology and selected mechanical properties of prepared polymer systems were investigated. It was found that increasing amount of TPU in polymer blends resulted in decreasing of tensile properties, rebound resilience and abrasion resistance of the final materials. Microstructural analysis showed that material breaks at interface between GTR and RPE or TPU, during the static tensile test.

Synthesis, structure and properties of poly(ester-urethane)s obtained using bio-based and petrochemical 1,3-propanediol and 1,4-butanediol

In this paper, the poly(ester-urethane)s obtained using petrochemical and bio-based chain extenders were prepared and characterized. The influence of glycols’ origin on the chemical structure, mechanical and thermal properties of the prepared polyurethanes was studied. The materials were synthesized by prepolymer method. The first step involved the reaction of α,ω-dihydroxy(ethylene-butylene adipate) (POLIOS 55/20) with 4,4′-diphenylmethane diisocyanate (MDI). In the next step, obtained prepolymer terminated with isocyanate group was extended using 1,3-propanediol and 1,4-butanediol at three different molar ratios of NCO group (presented in prepolymer chains) to OH groups (presented in chain extender structure), i.e., 0.95, 1.0 and 1.05. The results showed that applying the different types (diversified chemical structure and origin) of glycols results in obtaining materials with diversified mechanical properties and slight different thermal stabilities. The results of Fourier transform infrared spectroscopy showed that the chemical structure of the obtained polyurethanes was not affected by the presence of glycols with the same chemical structure and different origins (petrochemical and bio-based nature).

Effect of high loading of titanium dioxide particles on the morphology, mechanical and thermo-mechanical properties of the natural rubber-based composites

The aim of this work was to prepare and characterize the natural rubber vulcanizates containing different amounts of titanium dioxide particles. At first, a rubber mixture was prepared using a laboratory two-roll mill and then samples were vulcanized by a hydraulic press. The formulation of the rubber mixture and rubber-processing technique were based on our earlier investigations. Samples were obtained with different titanium dioxide loadings of 15, 25, 45, and 85 parts by weight per hundred parts of natural rubber. This research is focused on the determination of the influence of different loadings of titanium oxide particles on the chemical structure, morphology, mechanical and thermo-mechanical properties of the natural rubber-based composites. It was found that vulcanizates with different amounts of TiO2 particles possess good characteristic in terms of all measured properties. The results of Fourier transform infrared spectroscopy analysis showed that the chemical structure of the obtained natural-based composites was not influenced by titanium dioxide particles. The SEM micrographs showed the uniform dispersion of TiO2 particles in the natural rubber matrix. The agglomeration of filler was seen at the higher contents of TiO2 in the matrix. The thermogravimetric analysis showed slightly different thermal stability for the obtained natural rubber composites. The dynamic mechanical thermal analysis showed that the prepared materials have similar glass transition temperatures. However, increase in the content of titanium dioxide in the obtained materials is connected with higher energy loss (higher dissipation of energy) during the mechanical work of material and higher cross-link density of the prepared materials.

Influence of selected submicron inorganic particles on mechanical and thermo-mechanical properties of unsaturated polyester/glass composites

In this paper, the influence of different submicron-scaled particles (zinc oxide, titanium dioxide, or silica) on mechanical and thermo-mechanical properties of unsaturated polyester matrix composites reinforced with glass fabric was investigated. Surface morphology of obtained composites was also examined. At first inorganic particles were mechanically dispersed into unsaturated polyester resin system as per the calculated weight ratio (2 or 4 wt% of polymer matrix). For prepared liquid dispersions viscosity was measured. Composites were produced by using hand lay-up method and contained 39–41 wt% of glass fibers. The flexural and dynamic mechanical analyses were carried out for each group of fabricated polyester/glass composites. All results were compared with the control samples (without submicron particles). It was found that addition of 2 wt% ZnO or TiO2 to unsaturated polyester resin enhanced the flexural strength and flexural modulus of composites. Dynamic mechanical analysis showed the increase of storage and loss modulus. Similar effect of submicron-scaled inorganic particles on Tg value of composites was observed. The scanning electron microscopic analysis of prepared composites showed good dispersion of submicron particles in polymer matrix and generally absence of voids was also observed.

The Effect of High Molecular Weight Bio-based Diamine Derivative of Dimerized Fatty Acids Obtained from Vegetable Oils on the Structure, Morphology and Selected Properties of Poly(ether-urethane-urea)s

In this work, the effect of the high molecular weight bio-based diamine on the chemical structure and selected properties of poly(ether-urethane-urea)s has been investigated. The ether-urethane prepolymer was cured using 1,4-butanediol and/or bio-based diamine. Mentioned chain extenders were used separately or in the mixture, and their different molecular weight and chemical structure resulted in obtaining materials with diversified mechanical performence. The presence of specific chemical groups (i.e. urethane and urea groups) was confirmed by FTIR method. For the synthesized poly(ether-urethane-urea)s morphology and fracture mechanism, thermo-mechanical properties and mechanical properties were determined and discussed. Results confirmed that bio-based diamine acts as soft segments, and this is connected with changing of mechanical and thermo-mechanical properties of prepared partially bio-based poly(ether-urethane-urea)s. The increasing content of bio-based diamine resulted in increasing of tensile modulus and decreasing of tensile strength and elongation at break, and this is resulted from chemical structure of bio-based diamine (i.e. presence of aliphatic side chains).

Recycling of Polyurethanes

Abstract Concerns over growing amounts of plastic waste produced every year has resulted in development of mechanical and chemical recycling methods of polymers. The sustainable development of society should be connected with rational and efficient using of petrochemical and bio-based resources. In the case of polyurethane waste, the most important is an effective collection and an effective recycling by mechanical and chemical methods. It results from requirements connected to preventing pollution and protecting the environment. Moreover, reusing and recycling of plastics can reduce the cost of the production new products and improve the materials waste utilization. The low density and the high production level of the polyurethane foams (applied in, e.g., automotive and truck seating or thermal insulations) resulted in some difficulties during the processing or disposing of in the landfill. A similar problem is generated by polyurethane elastomers and thermoplastics waste (from structural parts or footwear). The utilization of polyurethanes waste by thermal decomposition (e.g., incineration) results in the production of poisonous gases, which are dangerous in the terms of the environment and the human health. According to the literature, there are two main ways of polyurethane waste recycling: physical and chemical recycling methods. Physical recycling is directly reusing polyurethane waste without chemical treatment. Chemical recycling is realized by the degradation of polymer chemical structures, in the case of polymers, this is obtained by the polycondensation or polyaddition. The polyurethanes waste can be depolymerized to olygomers terminated with hydroxyl groups, and this semiproduct can be used as a part of polyol component for the synthesis of new polyurethane materials. Therefore, this chapter aims to present issues related to mechanical, chemical and thermo-chemical methods of polyurethanes recycling. Moreover the recovery of energy and landfill in the case of polyurethanes waste were discussed.

Synthesis, structure and properties of poly(ether-urethane)s synthesized using a tri-functional oxypropylated glycerol as a polyol

The main aim of this work was to obtain poly(ether-urethane)s using tri-functional polyoxyalkylene polyol (Rokopol G1000), which introducing the chemical cross-links into the structure of polyurethanes. Poly(ether-urethane)s were prepared using two-step method, called prepolymer method, which involves in the first step the reaction of 4,4′-diphenylmethane diisocyanate (MDI) and tri-functional polypropylene glycol glycerol triether polyol. In the second step, prepolymer chains were extended by using: 1,6-hexanediol, 1,4-butanediol in the mixture with poly(ethylene glycol) and poly(ethylene glycol). The prepolymer chains extending was realized at three different molar ratios of NCO groups (presented in prepolymer) to OH groups (presented in chain extender), i.e., 0.95, 1.00 or 1.05. The influence of chain extender type on the chemical structure, selected mechanical properties and thermomechanical properties of the obtained poly(ether-urethane)s was investigated. The results showed that applying different types of chain extenders results in obtaining materials with diversified mechanical properties, but very similar thermal stability. The performance of obtained poly(ether-urethane)s is mostly affected by the chemical cross-links, which were introduced into soft segments by tri-functional polyetherol.

Mechanical Recycling via Regrinding, Rebonding, Adhesive Pressing, and Molding

Abstract Increasing amount of polyurethane foams waste (e.g. from the building or furniture industry) produced every year resulted in the intensive development of their recycling methods. This chapter covers most important mechanical recycling methods, i.e. regrinding, rebonding, adhesive pressing, and molding. The procedure, required equipment and chemicals (if needed) for each method were described. The possible applications of the products obtained by mechanical recycling of polyurethane foams (for example flakes, powders or molded parts) were also presented.