EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES OF POLYURETHANE POWDER COMPOSITES

In this paper, the effects of emery, lime, quartz sand and cement on the mechanical properties of polyurethane powder composites were studied by three-point flexural test, and the stress-strain curve was drawn. In the flexural test, the polyurethane cement composite formed a control group by changing the content of polyester polyol. When polyester polyol: isocyanate: cement =1:1:2, the average flexural strength of polyurethane cement was 37.1 MPa, and the strain was 10854 με.When polyester polyol: isocyanate: cement =1.15:1:2, the average flexural strength is 38.9 MPa and the strain is 23520 με.When polyester polyol: isocyanate: cement =1.3:1:2, the average flexural strength is 42.5 MPa and the strain is 32942 με. The flexural strength and ductility are improved to a certain extent due to the addition of polyester polyol.The average flexural strength of other polyurethane powder composites such as polyurethane emery test block is 45.1 MPa and the strain is 6203 με, the average flexural strength of polyurethane lime test block is 33.4 MPa and the strain is 6470 με, the average flexural strength of polyurethane quartz sand test block is 49.23 MPa and the strain is 7521 με. The results show that the flexural strength of polyurethane emery material and polyurethane quartz sand material is higher than that of polyurethane cement, which can be used to replace cement to a certain extent to reduce the cost of polyurethane composite material.

Eco-Friendly Ether and Ester-Urethane Prepolymer: Structure, Processing and Properties

This study concerns bio-based urethane prepolymers. The relationship between the chemical structure and the thermal and processing parameters of bio-based isocyanate-terminated ether and ester-urethane prepolymers was investigated. Bio-based prepolymers were obtained with the use of bio-monomers such as bio-based diisocyanate, bio-based polyether polyol or polyester polyols. In addition to their composition, the bio-based prepolymers were different in the content of iso-cyanate groups content (ca. 6 and 8%). The process of pre-polymerization and the obtained bio-based prepolymers were analyzed by determining the content of unreacted NCO groups, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, thermogravimetry, and rheological measurements. The research conducted facilitated the evaluation of the properties and processability of urethane prepolymers based on natural components. The results indicate that a significant impact on the processability has the origin the polyol ingredient as well as the NCO content. The thermal stability of all of the prepolymers is similar. A prepolymer based on a poly-ether polyol is characterized by a lower viscosity at a lower temperature than the prepolymer based on a polyester polyol. The viscosity value depends on the NCO content.

Biobased Waterborne Polyurethane-Ureas Modified with POSS-OH for Fluorine-Free Hydrophobic Textile Coatings

Waterborne polyurethane-urea dispersions (WPUD), which are based on fully biobased amorphous polyester polyol and isophorone diisocyanate (IPDI), have been successfully synthesized obtaining a finishing agent that provides textiles with an enhanced hydrophobicity and water column. Grafting of trans-cyclohexanediol isobutyl POSS (POSS-OH) to the biobased polymer backbone has also been investigated for the first time and its properties compared to a standard chain extender, 1,3-propanediol (PDO). The chemical structure of WPUD has been characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The thermal properties have been evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical properties have been studied by tensile stress–strain analysis. Moreover, the particle size, particle size distribution (PSD), and stability of developed waterborne dispersions have been assessed by dynamic light scattering (DLS), Z-potential, storage aging tests, and accelerated aging tests by analytical centrifuge (LUM). Subsequently, selected fabrics have been face-coated by the WPUD using the knife coating method and their properties have been assessed by measuring the water contact angle (WCA), oil contact angle (OCA), water column, fabric stiffness, air permeability, and water vapor resistance (breathability). Finally, the surface morphology and elemental composition of uncoated and coated fabrics have been studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. All of the synthesized polyurethane-ureas provided the coated substrates with a remarkable hydrophobicity and water column, resulting in a more sustainable alternative to waterproof coatings based on fluoropolymers, such as PTFE. Grafting POSS-OH to the polymeric backbone has led to textile coatings with enhanced hydrophobicity, maintaining thermal, mechanical, and water column properties, giving rise to multifunctional coatings that are highly demanded in protective workwear and technical textiles.

Synthesis of Mono (Ethylene Glycol)-Based Polyurethane and Effect of Chain Extender on Its Associated Properties

This study depicts the investigations of the effect of composition of aromatic polyester polyol produced from terephthalic acid (TPA) and different concentrations of monoethylene glycol (mEG) as a chain extender on the mechanical properties of polyurethane (PU) elastomer. Aromatic polyester polyols are prepared via the poly-esterification of adipic acid, terephthalic acid, catalyst, and mono ethylene glycol; while a polyurethane elastomer is formulated via the pre-polymerization of polyol with pure monomeric Methylene diphenyl diisocyanate (MDI.) Mechanical properties of polyurethane elastomers are examined, such as hardness via shore A hardness, apparent density via ASTM (American Society for Testing and Materials) D1622–08, and abrasion wear resistance via a Deutches Institut fur Normung (DIN) abrasion wear resistance tester. Structural properties are investigated through Fourier-transform infrared spectroscopy (FTIR) analysis. Results reveal that the shore A hardness of the PU elastomer increases with an increasing concentration of mEG from 4g to 12g. Nevertheless, the elastomer’s density depicts a reduction with an increasing extender content. The abrasion wear resistance of polyurethane, however, increases with an increasing concentration of glycol. A structural analysis through FTIR confirms the formation of polyurethane elastomer through the characteristic peaks demonstrated.

Flame Retardant Waterborne Polyurethanes: Synthesis, Characterization, and Evaluation of Different Properties

A series of flame retardant waterborne polyurethanes (WBPUs) with varying NCO:OH mole ratio, i.e., isocyanate:hydroxyl groups, was synthesized using phosphorus-based polyester polyol and isophorone diisocyanate (IPDI). The phosphorus moiety was kept in the polymeric chain, which improves flame retardancy of the WBPU films. The prepolymer mixing process was adopted for the synthesis route of WBPU systems. The presence of structural-functional groups was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The thermal stability and percentage char yield were observed by TGA analysis. As a consequence of the existence of phosphorous moiety, these WBPUs also exhibit flame retardancy, which was examined by limiting oxygen index (LOI) and UL-94 test. All the samples show an increment in thermal stability with an increase in NCO:OH ratio. Maximum flame retardancy was obtained in FWP5 and FWP6 systems with LOI value of 32%.

Influence on Polyurethane Synthesis Parameters Upon the Performance of Base Asphalt

The objective of this study aims to investigate the performance of thermoplastic polyurethane elastomers (TPU)-modified asphalt, with special focus on the influence of polyurethane synthesis parameters upon the performance of base asphalt. In this study, the TPU modifier was incorporated into base asphalt to prepare TPU-modified asphalt by using a self-determined laboratory process. The properties of polyester-based TPU and polyether-based TPU modified asphalt with different contents was analyzed by the base performance tests. The Fourier transform infrared spectroscopy (FTIR), fluorescent microscope, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravity (TG), dynamic shear rheology (DSR), and bending beam rheology (BBR) tests were conducted to expose chemical, microstructure, and rheological properties of the asphalt binders, respectively. The results indicated that the modified asphalt with 5% TPU modifier exhibited a favorable performance in terms of the penetration, ductility, softening point, and rotational viscosity, respectively. The isocyanate and polyol reacted to form carbamate in the TPU-modified asphalt, and moreover the isocyanate and aromatic compounds reacted to form halohydrins in the asphalt. Large particles contained in the polyester-based TPU-modified asphalt increased obviously with the increase of Ch (Hard segment content) and r (Isocyanate root index, molar ratio between NCO and OH) value, the fracture mode of it subjected to external load indicated a typical brittle fracture. The content of MDI in the synthesized polyurethane modifier was an important factor affecting the high-temperature stability of the modified asphalt. The polyester-based TPU modifier had a better high temperature performance than the polyether-based TPU modifier. The polyether polyol chain segment showed a greater flexibility as compared to polyester polyol; the addition of polyether polyols can be effectively offset of MDI chain rigidity as r ≤ 1 and Ch < 40% leading to the improvement of the viscoelastic property of asphalt. When Ch = 40% and r = 0.95, the polyether-based TPU-modified asphalt exhibited the same high-temperature grade as the polyester-based TPU-modified asphalt, whereas the polyether-based TPU-modified asphalt showed obviously higher low temperature grades. The polyester-based TPU with Ch = 40% and r = 1 can be used as a modifier to increase the durability of asphalt binders.

RATIONAL DISPOSAL OF PET CONTAINING WASTE AND PROSPECTS FOR THE SYNTHESIS OF NEW POLYMERS

As a result of the research on the utilization of polyethylene terephthalate-containing household waste, a promising direction was identified in the production of a new type of secondary polyethylene terephthalate (SPET) - unsaturated polyesters. It was revealed that the final product, which formed when the alcoholization process is complete in any proportion of of glycol and secondary polyethylene terephthalate, is the bisalkylent terephthalate of terephthalic acid; the content of the alcoholysis product consists of bisalkylent terephthalate, different molecule mass, functionally hydroxyl-containing complex polyester polyol and free diols. The laws of alcoholization of secondary polyethylene terephthalate have been studied and the mechanism has been established. Studies have shown that, in contrast to existing theories, such as the formation of ethylene glycol in the polycondensation of phthalic anhydride bisalkylene glycol derivatives, the increase in ethylene glycol in the process was found to be due to the exchange of diethylene glycol in the macrochain. The formation of unsaturated polyesters goes stage by stage, first ethylene-, diethylene glycol acid esters are formed, then they are exposed to hydroxyl-containing oligomers - secondary polyethylene terephthalate alcohol products. A mathematical model of the process of alcoholization of SPET and diethylene glycol was created, studies showed that the difference between the values obtained as a result of the mathematical model and experiments are less than 5%. The unsaturated polyesters were synthesized on the basis of SPET alcoholization products. Many of them have shown their superiority over unsaturated polyesters PN-1, PN-3, PN-15, which are used in industry for general purposes. By developing unsaturated polyesters on the basis of secondary polyethylene terephthalate alcohol products, it was found that the structure of these polyesters is close to that of imported resins "Body", 196, 196A, used in industry.

Biobased Waterborne Polyurethane-Urea/SWCNT Nanocomposites for Hydrophobic and Electrically Conductive Textile Coatings

Waterborne polyurethane-urea dispersions (WPUD), which are based on 100% bio-based semi-crystalline polyester polyol and isophorone diisocyanate, have been successfully synthesized and doped with single-walled carbon nanotubes (SWCNT) to obtain a finishing agent that provides textiles with multifunctional properties. The chemical structure of WPUD has been characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The thermal properties have been evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). Mechanical properties have been studied by tensile stress–strain analysis. Moreover, the particle size, particle size distribution (PSD), and stability of developed waterborne dispersions have been assessed by dynamic light scattering (DLS), Z-potential, and accelerated aging tests (analytical centrifugation). Subsequently, selected fabrics have been face-coated by the WPUD using knife coating method and their properties have been assessed by measuring water contact angle (WCA), water column, fabric stiffness, and air permeability. The electrical conductivity of textiles coated with SWCNT-doped WPUD has been evaluated by EN 1149 standard. Finally, the surface morphologies of uncoated and coated fabrics have been studied by scanning electron microscopy (SEM). All of the synthesized polyurethane-ureas provide the coated substrates with remarkable water-repellency and water column, being therefore a more sustainable alternative to waterproof coatings based on fluoropolymers, such as PTFE. The additivation of the polymeric matrices with SWCNT has led to textile coatings with excellent electrical conductivity, maintaining water column properties, giving rise to multifunctional coatings that are highly demanded in protective workwear and technical textiles.