Influence of biobased polyol type on the properties of polyurethane hotmelt adhesives for footwear joints

The oxo-degradation process of high-impact polystyrene (HIPS) with 0, 1.5 and 3% w/w of pro-oxidant d2w® was studied. The degradation was conducted in a convection oven employing temperatures of 50, 55, 60 and 65 °C. The process was monitored by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile tests (i.e., strain at break). Neat HIPS samples did not exhibit significant changes for all conditions evaluated. Samples with oxo-additive exhibited a complex behavior in relation to the rate of degradation; HIPS with 1.5% oxo-additive exhibited faster degradation than samples with 3% oxo-additive at temperatures of 50 and 55 °C, but no significant differences at 60 and 65 °C. FTIR studies showed the evolution of hydroxyl and carbonyl functional groups during degradation and allowed to infer that polybutadiene phase is degraded preferentially. A complete loss of mechanical properties of samples with pro-oxidant was observed with changes occurring faster as temperature increased. Tensile and DSC tests were the most effective techniques for monitoring the degree of decomposition of HIPS, since the results obtained evidenced early structural changes during thermal aging that were undetected by FTIR and TGA at identical exposure times.

Multi-parametric flowability classification of self-compacting concrete containing sustainable raw materials: An approach to real applications

A novel quinoline-containing benzoxazine resin, 8HQ-fa, has been successfully synthesized at room temperature using sustainable raw materials, such as 8-hydroxyquinoline and furfurylamine as the phenol and amine source, respectively. The chemical structure of the hereinafter referred to as quinolinoxazine is fully characterized by Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance spectroscopy (NMR), as well as by 2D 1H–1H nuclear Overhauser effect spectroscopy (NOESY) and 1H–13C heteronuclear multiple quantum correlation (HMQC) NMR. Thermal properties and polymerization behavior of the monomer are studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The resulting polymer is also characterized in terms of its thermal and fire-related properties by DSC, TGA, and microscale combustion calorimetry (MCC). The resulting thermoset, poly(8HQ-fa), presents good thermal stability as evidenced by its Tg (201 °C), Td5 and Td10 (307 and 351 °C, respectively), and char yield (42%), and low flammability as determined by the LOI, heat release capacity, and total heat released values (34.3, 143 J/gK, and 10.8 kJ/g, respectively), making it a self-extinguishing thermoset. The combination of properties and advantages in the synthesis of 8HQ-fa, accompanied by a low polymerization temperature, suggests its great potential in the field of high-performance polymers.

The effects of adding nanoclay to improve the thermal and mechanical properties of polypropylene (PP) copolymers grade (EPD60R) used in the pipe industry were investigated. To improve the dispersion of the nanoclay in the polymeric matrix, a 30 wt% of nanoclay master batch was first prepared by mixing PP matrix maleic anhydride PP oligomer (PP-g-MA) and Cloisite® 15A (C15A) nanoclay. The prepared master batch was used to produce nanocomposites with 2 and 5 wt% nanoclay. The nanocomposites were analyzed by XRD (X-ray diffraction), SEM (Scanning electron microscopy), DSC (Differential scanning calorimetry), TGA (Thermogravimetric analysis), and other mechanical tests. The XRD and SEM results indicated the occurrence of an intercalated layer structure in the nanocomposites. Thermal properties of the nanocomposites were investigated using DSC and TGA tests. The crystallinity of the 2 wt% nanoclay was improved by about 59.23% in the nanoclay reinforced samples. As the content of nanoclay increased, the composite exhibited higher thermal degradation temperature. Performing a limiting oxygen index (LOI) test on the samples showed that the addition of nanoclay to the EPD60R matrix increased the flame retardancy by 12.58%. The tensile modulus of the nanocomposites was improved compared to the pure polymer, while the elongation at break and at yield showed a reduction. To investigate the nanocomposite in pipe application, a pipe (external diameter 110.8 and thickness 3.65 mm) was manufactured in a special tube extruder machine with 2 wt% of C15A. Tests of the tube’s physical and mechanical properties indicated that its ring stiffness increased by 25% compared to the pure PP.

Synthesis of a high-performance citric acid-based polyester elastomer by a hot-pressing technique

To understand the role of molecular structure on the crystallization behavior of copolyester in thermoplastic poly(ether ester) elastomers (TPEEs), series of poly(butylene-co-1,4-cyclohexanedimethylene terephthalate) (P(BT-co-CT))-b-poly(tetramethylene glycol) (PTMG) are synthesized through molten polycondensation process. The effects of poly(cyclohexanedimethylene terephthalate) (PCT) content on the copolymer are investigated by Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR), gel permeation chromatographs (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical, and visible light transmittance tests. FT-IR and NMR results confirm the incorporation of PCT onto the copolymer. WAXD and DSC indicate that the crystalline structure of the copolymers changed from α-PBT lattice to trans-PCT lattice when the molar fraction of PCT (MPCT) is above 30%, while both crystallization and melting temperatures reach the minima. An increase in MPCT led to an increase in the number sequence length of PCT, the thermal stability and the visible light transmittance of the copolymer, but to a slight decrease in tensile strength and elastic modulus.

Polymer electrolytes composed of an acrylonitrile and polyethylene glycol methacrylate copolymer poly(AN-co-PEGMA) with addition of NaClO4 are studied by impedance spectroscopy, differential scanning calorimetry (DSC), fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Hexagonal boron nitride (hBN) particles are having increasing interest owing to mechanical properties, thermal stability, chemical stability and good lubrication property. In this study, hBN was used as an inorganic filler. FTIR spectroscopy was used to examine the interactions between the host polymer and both NaClO4 salt and nano hBN particles. The thermal properties of the composites were studied using TGA and DSC tests. TGA results showed that all the composites membranes were thermally stable till 300°C with one step degradation. Surface morphology of the films was examined with SEM which also reveals the homogeneous dispersion of nano hBN in the polymer matrix. Ionic conductivity was studied with impedance spectroscopy, the results showed that the ionic conductivity increases with increasing PEGMA ratio. ANcoPEGMA 11 20Na (EO:Na ratio=20) sample showed maximum ion conductivity of approximately 3.6×10−4 S cm−1 at 100°C. This is because ANcoPEGMA 11 20Na has highest percentage of PEGMA and highest number of Na+ ion per EO groups.

The insulation state assessment of two 200 kV HVDC XLPE cables, which have been in operation for 5 years, were performed after a breakdown fault. The electrical test including broadband dielectric spectrum (BDS) test and breakdown strength test. The material test including thermal stimulation current (TSC) test, differential scanning calorimetry (DSC) test, infrared spectrum test, degree of crosslinking test, and thermal elongation ratio test. The results show that the TSC and DSC test can represent the differences due to different breakdown energy between two cables. And the BDS, TSC and DSC test can distinguish between old and new cables. Meanwhile three indicators, including infrared spectrum, degree of crosslinking and thermal elongation ratio test of old cables were even better than new cables.

Poly(hydroxyalkanoates) (PHAs) are emerging as sustainable materials in packaging and medical device industries. Nevertheless, the high cost and the need to improve the mechanical properties have limited their widespread use. Blending with other bio-based polymers, such as poly(lactic acid) (PLA), has been proposed in previous studies. This study investigates the effects of temperature, azodicarbonamide (AZ, foaming agent), boron nitride (BN, filler), and multilayer film/foam coextrusion on the properties of a blend containing an amorphous PHA and PLA. The effect of twin-screw micro-compounder temperature (185 °C & 205 °C) and BN concentrations of 1, 2, 3, 5, and 10 wt% (185 °C) on the properties of the PHA/PLA blend were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. Design of experiments (DoE) was used to find the optimal concentrations of AZ and BN (205 °C) using JMP® software. The response surface analysis predicted an optimal design based on the target response levels (modulus, tensile strength, strain at break, and toughness). This formulation was prepared and characterized using DSC, TGA, tensile, and melt flow index (MFI) measurements. Finally, this formulation was processed via film/foam coextrusion and examined using scanning electron microscopy (SEM) and density measurements. This study demonstrated that AZ and BN can be used to manipulate the mechanical properties and crystallinity of PHA/PLA blends, while reducing the overall material cost via density reduction (20–21% for the optimal formulation). Furthermore, reducing the concentration of AZ using the I-optimal design in this study could alleviate the toxicity concerns for food packaging.

Cellulose microfibers surface treated with imidazole as new proton conductors

Since rigid polyurethane (PU) foams are one of the most effective thermal insulation materials with widespread application, it is an urgent requirement to improve its fire retardancy and reduce the smoke emission. The current work assessed the fire behavior of PU foam with non-halogen fire retardants system, containing histidine (H) and modified graphene oxide (GOA). For investigated system, three loadings (10, 20, and 30 wt.%) were used. The Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis, cone calorimetry (CC) and smoke density chamber tests as well as pre- and post-burning morphological evaluation using scanning electron microscope (SEM) were performed. Moreover, TGA combined with FT-IR was conducted to determine the substances, which could be evolved during the thermal decomposition of the PU with fire retardant system. The results indicated a reduction in heat release rate (HRR), maximum average rate of heat emission (MAHRE), the total heat release (THR) as well as the total smoke release (TSR), and maximum specific optical density (Dsmax) compared to the polyurethane with commercial fire retardant, namely ammonium polyphosphate (APP). A significantly improvement, especially in smoke suppression, suggested that HGOA system may be a candidate as a fire retardant to reduce the flammability of PU foams.

Silica nanoparticles (SNPs) were modified by different amounts of 3-aminopropyltriethoxysilane (APTES). Nanocomposites based on ethylene vinyl acetate copolymer (EVA) and modified SNP (m-SNP) were prepared by the melt mixing method. They were characterized by Haake torque measurement, differential scanning calorimetry (DSC), horizontal burning test, scanning electron microscopy. Accelerated weather testing of the nanocomposites was performed according to ASTM D4329 (cycle A) for 168 h. The Haake torque indicates that the relative melt viscosity of EVA/m-SNPs is slightly higher than that of EVA/SNP nanocomposites. The DSC and burning test results show that m-SNPs decrease crystallinity degree and flammability of EVA. After accelerated weather testing, the relative amount of C=O groups in EVA/m-SNP nanocomposites is lower than that in EVA/SNP nanocomposites. Micro crack of EVA/m-SNP nanocomposite is smaller than that of EVA/SNP nanocomposite. In our study, the EVA/m-SNP nanocomposites with good tensile properties, flame and weather resistance can be used as sustainable materials in some technique fields.

Characterization and processability of post-consumer, double-recycled high impact polystyrene from disposable cups

UV-thermal dual cured anti-bacterial thiol-ene networks with superior performance from renewable resources

SPI/PVA films were successfully prepared with complex plasticizers containing urea and trethanolamin (TEA) by casting and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), ultraviolet (Uv-vis), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. The results indicated that SPI/PVA films with the content of 40% complex plasticizers possessed better optical transmittance. All of the films exhibited only one Tg in DSC curves. Moreover, the SPI/PVA films with complex plasticizers had higher thermal stability and mechanical properties, as a result of the strong interaction between complex plasticizers and SPI/PVA. The SPI/PVA materials will be promising for the application in the field of package and container, substituting for the nongreen polymers.