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Binary epoxy resins, diglycidyl ethers of bisphenol A and polytetramethylene glycol, were cured by binary amine hardeners, isophorone diamine and polyoxybutylene diamine, in the presence/absence of...

Thermoplastic Polyurethane (TPU) is a unique tailorable material due to the interactions of hard and soft segments within the block-copolymer chain. Therefore, various products can be created out of this material. A general trend towards a circular economy with regards to sustainability in combination with TPU being comparably expensive is of high interest to recycle production as well as post-consumer wastes. A systematic study investigating the property changes of TPU is provided, focusing on two major aspects. The first aspect focuses on characterizing the change of basic raw material properties through recycling. Gel permeation chromatography (GPC) and processing load during extrusion indicate a decrease in molar mass and consequently viscosity with an increasing number of recycling cycles. This leads to a change in morphology at lower molar mass, characterized by differential scanning calorimetry (DSC) and visualized by atomic force microscope (AFM). The change in molar mass and morphology with increasing number of recycling cycles has an impact on the material performance under tensile stress. The second aspect describes processing of the recycled TPU to nonwoven fabrics utilizing melt blowing, which are evaluated with respect to relevant mechanical properties and related to molecular characteristics. The molar mass turns out to be the governing factor regarding mechanical performance and processing conditions for melt blown products.

In this study, 4,4′-diphenylmethane diisocyanate and polytetramethylene glycol were used to prepare a prepolymer; N,N′-bis(4-hydroxybenzylidene)-2,6-diaminopyridine (BHBP) was used as a chain extender; and these elements were combined to prepare a novel polyurethane, BHBP/PU. Gel permeation chromatography revealed that the molecular weight of the BHBP/PU samples increased as the BHBP content was increased. Fourier transform infrared spectroscopy demonstrated that high BHBP content facilitated strong hydrogen bonding in the samples. Differential thermogravimetry indicated that the initial decomposition temperature of BHBP/PU-3 was approximately 10 °C higher than that of BHBP/PU-1. Differential scanning calorimetry and dynamic mechanical analysis revealed that increasing the BHBP content substantially increased both the glass transition and dynamic glass transition temperatures of the BHBP/PU samples. The tensile strengths of BHBP/PU-1, BHBP/PU-2, and BHBP/PU-3 were 7.7, 10.9, and 21.6 MPa, respectively, with corresponding Young’s moduli of 0.7, 1.9, and 3.3 MPa. These results demonstrated that both the tensile strength and Young’s modulus of the BHBP/PU samples increased as the BHBP content was increased. Moreover, the BHBP/PU samples exhibited excellent shape recovery of >90%.

Thermoplastic polyurethane/graphene nanoplatelets conductive composite was in situ synthesised by ball milling at room temperature, using polytetramethylene glycol as soft segment, 4-methyl-m-phenylene diisocyanate as hard segment, 1,4-butanediol as chain-extending agents, graphene nanoplatelets as conductive filler. Carbon black was used as contrast conductive filler, stir was used as contrast method. The mechanisms and influence of different ball milling time to exfoliate layered graphene nanoplatelets and compound with thermoplastic polyurethane resin were studied. The morphology, electrical, mechanical and thermal properties of thermoplastic polyurethane/graphene nanoplatelets composite were investigated too. It showed that ball milling was an effective method to prepare thermoplastic polyurethane/graphene nanoplatelets conductive composite of low loading level by avoiding aggregation of graphene nanoplatelets. The percolation threshold effect of thermoplastic polyurethane/graphene nanoplatelets composite by ball milling 6 h occurred at the content around 2 wt% of the graphene nanoplatelets, which was much lower than 6 wt% of that prepared by stir. Besides, thermoplastic polyurethane/graphene nanoplatelets composite showed much better conductive and mechanical properties than thermoplastic polyurethane/carbon black composite.

A series of castable polyurethane elastomers, based on polytetramethylene glycol as soft segments and toluene diisocyanate, 4, 4’-diphenylmethane diisocyanate, P-phenylene diisocyanate as diisocyanates respectively, were synthesized. The dynamic mechanical analysis method was utilized to determine tan delta property (tanδ). Also the influence of diisocyanates on the dynamic mechanical properties of castable polyurethane elastomers was analyzed. It can be concluded that the P-phenylene diisocyanate system elastomers have the most excellent dynamic mechanical properties.

The mechanical properties were investigated of a series of PA-PEG thermalplastic elastomer based on PA1010 and polytetramethylene glycol (PEG) with varying hard and soft segment content. Dynamic mechanical measurements of these polymers have carried out over a wide range of temperatures. The block copolymers exhibit three peaks, designated as α, β and γ in the tanδ-temperature curve. The α transition shifts to higher temperature with increasing hard block molecular weight. However, at a constant hard molecular weight, the α transition shifts to higher temperature and the damping increases on increasing the soft segment molecular weight. DMA results show that the block copolymers exhibit a microphase separation structure and both soft and hard segments were found to be crystallizable. The degree of phase separation increases with increasing hard block molecular weight.

Segmented block copolymers (PA1010-b-PEG) based on α,ω-dicarboxy-polyamide-1010 (PA1010dC, = 1000, 2000, 3000 and 5000) and α,ω-dihydroxy-polytetramethylene glycol (PEG, = 1000, 2000) were synthesized by melt condensation. Various block copolyamides with different block lengths of the hard and soft segments were obtained, and their composition and block lengths were determined via FT-IR and 1H-NMR.

Castable polyurethane elastomer based on polytetramethylene glycol (PTMEG) and 2,4-toluene diisocyanate (TDI) was prepared with low free TDI monomer content prepolymer (LF-prepolymer), the structure and properties of the prepolymers and corresponding elastomers were characterized. The result showed that, LF-prepolymer exhibit low viscosity, low molecular weight and narrow molecular weight distribution. The polyurethane prepolymer based on LF-prepolymer show higher bashore rebound, lower compression set and better dynamic properties.

Single-layer silica films modified with polytetramethylene glycol (PTMEG) were prepared via sol-gel process in the presence of NH4OH as catalyst. Compared with the pure SiO2 coating, the hybrid films possessed higher lased-induced damage threshold (LDT). The characterization results from AFM and TEM indicated that the introduction of PTMEG molecules changes the structure of the colloidal silica matrix, which directly resulted in the improvement of the transparency and LDT.

A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50°C. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.

Various ER fluids were prepared based on polyethers such as polypropylene glycol and polytetramethylene glycol. The polyethers were modified with isocyanates to give homogeneous liquids which show a positive or a negative ER effect depending on the molecular structure. The molecular motion of an urea-derivative of the polyether was analyzed with the NMR relaxation method. The modified polyethers were also used as a component of immiscible blends with silicones and suspensions. The immiscible blends showed a positive ER effects even when the polyether showed a negative ER effect. The suspensions tended to show a positive ER effect, which is similar to usual ER suspensions.

The composite electrolytes (CEs) were prepared by impregnating the ternary composites comprising polypropylene glycol-based waterborne polyurethane (denoted as WPU(PPG)), polytetramethylene glycol-...

A facile synthesis of eight novel diisocyanates, viz. N,N-bis(isocyanatoalkyl)-1,2,4,5-benzenetetracarboxylic-1,2:4,5-diimides and N,N-bis(isocyanatoalkyl)-3,3′,4,4′-benzophenonetetracarboxylic-3,3′:4,4′-diimides, containing built-in imide rings, which serve as intermediates for the preparation of polyurethanes containing imide rings in the main chain, is reported. The solution polyaddition reaction of four representative diisocyanates with polytetramethylene glycol is also described. The resulting amorphous, thermally stable poly(imide-urethane)s are soluble with inherent viscosities ranging from 0.36–0.83 dL/g in m-cresol.

X-ray investigations have been made into a series of PUs differing in the length of the flexible polytetramethylene glycol block ( M = 1000, 1410 and 2000) and different concentrations of ionogenic groups. It was established that increase in the length of the flexible block in the initial PU systems substantially improves the microphase separation of the rigid and flexible blocks expressed in increase in the degrees of segregation of the components from 10 to 70%. Depending on the MM of the flexible block significantly different patterns of change in the level of microphase separation were observed on introducing ionogenic groups: it remained practically unchanged for the sample with the flexible block of MM 2000 and gradually rose (degree of segregation rose from 10 to 70%) for the sample with the flexible block of MM 1000.

X-ray investigations of polytetramethylene glycol oligomers with various molecular weights were carried out. Interatomic distance correlation curves were obtained using the Fourier transformation of the intensity curves. Theoretical curves of the correlation of the intramolecular interatomic distances were also calculated. The calculation of these curves has been done using the results of conformational analysis for different conformational states of the PTMG chain. Correlation curves for the intermolecular distances were then obtained by subtraction of the theoretical curves from the experimental ones. The results obtained are considered in the framework of the various models of the structural state of liquid polymers. The model of kink isomers shows the best fit with our results.

12-Hydroxymethyltetrahydroabietanol has been polymerized with hexamethylene diisocyanate and a low molecular weight polyurethane produced. Low molecular weight polyurethanes have also been prepared from 12-hydroxymethyltetrahydroabietyl chloroformate, hexamethylenediamine, and sym.-dimethylethylenediamine. 12-Hydroxymethyltetrahydroabietanol has been “end-capped” with tolylene-2,4-diisocyanate and hexamethylene diisocyanate. The resulting diisocyanates have been polymerized with polytetramethylene glycol, hexamethylenediamine and hydrazine.