An Inherently Flame-retardant Bio-based Poly(ethylene 2,5-furandicarboxylate) Copolyester with High Impact Toughness and UV Shielding

Synergistically achieving high strength and impact toughness in Ti–6Al–4V-0.5Mo-0.5Zr alloy pipe with bimodal microstructure

High toughness, UV & blue light shielding and antibacterial bio-based PEF/TiO2 nanowires composites for packaging application

Our previous study (Macromolecule 2008, 41, 9204–9213) reported that annealing significantly increased the impact toughness of polypropylene (PP)/calcium carbonate (CaCO3) nanocomposites. We further investigated the underlying mechanism and report the results in this article. The impact strength of a high‐molecular‐weight PP filled with 20 wt % CaCO3 nanoparticles increased to 890 J/m upon 155°C‐annealing, about 20 times that of neat unannealed PP. This exceptionally high impact toughness is partially attributed to the high‐molecular‐weight PP, which provided strong ligaments. Moreover, this high‐molecular‐weight PP has a low concentration of cross‐hatched structure upon annealing, indicating that the cross‐hatched structure, which was suspected to be responsible for the annealing‐induced high impact toughness in the previous study, is in fact irrelevant to the annealing‐promoted impact toughness. A large number of cavities were observed in the impact‐fractured annealed nanocomposites because the difference in the stiffness between the crystalline and amorphous regions was enlarged upon annealing. These cavities, formed in the early stage of deformation, may have contributed to the annealing‐induced high impact toughness because these numerous cavities, in addition to the debonding of the CaCO3 nanoparticles, further released the plastic constraint of the PP matrix. Massive plastic deformation, therefore, became operative, leading to large energy dissipation. In addition, we found that the tensile toughness of the annealed nanocomposites was considerably reduced due to a significant reduction in the strain‐at‐break because the numerous cavities caused an earlier development of macro‐cracks, leading to smaller strain‐at‐breaks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The development of biobased polyesters with the combination of high UV shielding and degradability is a significant challenge. Herein, three 4-membered cyclic monomers containing two pyrrolidone and two furan rings were prepared by the aza-Michael addition of biobased bifuran diamine and dimethyl itaconate (DMI). They were available in melt polycondensation reactions with various diols to synthesize biobased polyesters. The bifuran structure endowed the polyesters with ultrahigh UV-shielding cutoff values of up to 443 nm, which achieved the highest UV-shielding results among the commercial polyesters. The bipyrrolidone structure conferred high hydrolysis sensitivity to the polyesters, which facilitated hydrolytic degradation of the polyester in an aqueous environment. The variability of the link structure between the multirings of the three monomers can regulate the various properties of the polyesters. Overall, the 4-membered cyclic monomers are promising precursors for sustainable biobased materials in providing high UV shielding and hydrolysis sensitivity.

In this present work, the UV shielding behavior of various mol percent of Ce doped mullite samples (CM0–5) were studied. The UV shielding behavior of mullite increasing with respect to ceria and reaching 78% of shielding tendency at 300 nm for CM5 was one of the fascinating outcomes of the study. Based on its exhibition of high shielding tendency, CM5 was chosen and functionalized with Glycidyl terminated silane. Subsequently, the resultant functionalized ceria doped mullite (FCM) was reinforced with polybenzoxazine (PBZ) matrix in order to build up FCM/PBZ nanocomposites. A detailed study was also conducted on the level of influence FCM yields in impacting properties such as UV shielding and thermo‐mechanical nature of FCM/PBZ nanocomposites. Upon analysis, it was determined that the 1.5 wt% FCM reinforced PBZ nanocomposite delivered 89% and 78% shielding efficiency at 300 and 200 nm UV region, respectively. Furthermore studies indicated that it exhibited 34% improved char yield, enhanced tensile strength, that is, 24.81% and 162°C as its glass transition temperature in comparison with neat PBZ matrix and other FCM/PBZ nanocomposites. These results suggest that the Ce doped mullite with high UV shielding properties can be used as a reinforcement to increase the UV shielding tendency of polymeric material which is of industrial significance. POLYM. COMPOS., 39:2073–2080, 2018. © 2016 Society of Plastics Engineers

Development of a glue- and heat- sealable acorn kernel meal/κ-carrageenan composite film with high-haze and UV-shield for packaging grease

The necessity of oil and gas exploration to attend the worldwide demand led to new challenges for engineering and materials development. The reserves of Pre-Salt in Brazilian coast is an example of such challenge, since it combines fields that are located at approximately 250 km off the coast, up to 3,000 meters deep water and corrosive environments. All these factors are detrimental to the pipeline making it necessary to develop new products that are capable to comply with demanding requirements for hostile environments, considering corrosion resistance in the presence of H2S, high strength, high toughness and heavy wall thickness to resist the external collapse pressure and good weldability for field installation. The UOE-SAWL process for pipe production enables the transportation of large amounts of oil and gas using large diameter pipes in safe conditions. In order to attend the main Brazilian projects, special requirements including DNV-OS-F101 have to be fulfilled by the pipe manufactures taking into account the as mentioned challenges to be overcome. The desired steel properties can be achieved by high end technologies in steelmaking, such as optimum rigorous alloying design, vacuum degassing and dynamic soft reduction, followed by Thermomechanical Control Process plus accelerated cooling (TMCP+ACC). The cleanness of the obtained steel associated with the accelerated cooled microstructure have an important role in the sour service resistance, weldability and mechanical properties. This paper presents the evaluation of mechanical properties and corrosive resistance of OD 24 in, WT 38.1 mm grade DNV 450 SFD produced according to DNV-OS-F101, supplementary requirements and corrosive tests carried out in conformance with NACE MR0175 and NACE TM0177. Good results were obtained in Charpy V-Notch tests of Base Metal, Heat Affect Zone and Weld, DWTT, CTOD and all the others required mechanical tests. Satisfactory results were also obtained in the HIC and SSC corrosive tests. The combination of all the obtained results make this pipe capable to face the challenges of the new exploration fields in Brazil. Introduction Nowadays long-distance offshore deepwater and ultra-deepwater pipelines have been and are still being built for the transportation of large quantities of oil and gas. The Brazilian offshore province began to attract the attention of the oil industry a couple of decades ago. The exploration of deepwater fields in the Presalt province and hence the necessity of oil and gas transportation, requires demanding material properties, leading pipe manufactures to seek for products excellence [1]. The pipes used for this application are commonly produced using the " UOE" process. This method provides many advantages in terms of product capacity, productivity, material properties and dimensional control. These applications require high strength, low D/t ratio in order to have good collapse resistance, high impact toughness, good weldability and sour resistance. In order to achieve the desired properties, the steel has been produced using the state of the art technology in steelmaking, such as optimum rigorous alloying design, vacuum degassing, dynamic soft reduction, etc. The effects of this technique, associated with the Thermomechanical Control Process plus the Accelerated Cooling (TMCP+ACC) resulted in enhanced material properties.

Titanium alloys with twinning- and transformation-induced plasticity effects display promising mechanical properties, particularly, high impact toughness, unlike conventional titanium alloys. This work focuses on a highly strain-hardenable Ti–Cr–Sn alloy displaying both TRIP and TWIP effects upon quasi-static loading and an average impact toughness of 193 J/cm2, which represents nearly three times the measured value for commercial titanium alloys. To account for this extremely high impact toughness, fracture and deformation features were quantified at different scales using scanning electron microscopy and transmission electron microscopy, particularly a Precession-Assisted Crystal Orientation Mapping system. Examinations evidenced the major role of twins in the fracture process, even on a sub-micrometre scale. The high impact resistance and absorbed energy of this alloy are explained by the positive contribution of dynamical refinement of the β grains with sub-twinning structures, whereas severe stress concentration may eventually contribute to ductile fracture, at least locally.

Reprecipitation induced isolation of ligand-free Cs4PbBr6 nanodisks as a green emissive UV light filter

We address here the continuing challenge and scientific gap in obtaining high impact toughness in medium-Mn steels. While addressing the challenge, the objective of the study described here is to obtain a fundamental understanding via critical experimental analysis of the reasons underlying high impact toughness that was successfully obtained in Fe-0.2C-6Mn-3Al medium-Mn TRIP steel. Electron microscopy and X-ray diffraction studies clearly underscored the absence of the TRIP effect in Fe-0.2C-6Mn-3Al medium manganese steel during impact and the volume fraction of austenite played a determining role in governing impact toughness. The highest impact toughness of 213.6 J · cm–2 was obtained when the steel was subjected to an intercritical hardening temperature of 700 °C and low tempering temperature of 200 °C. The presence of martensite in the microstructure reduced the impact toughness on quenching from 750 – 850 °C.

Low alloy CrMo steels are widely used for high temperature applications in the power and petrochemical industries as structural materials. The most crucial mechanical properties for these steels are sufficient strength to withstand internal pressure and high impact toughness to assure safety from momentary shock owing to unexpected accidents. Particularly, impact toughness deteriorates because of continuous high temperature during the operation of a high pressure vessel and embrittlement can occur. Thus, the use of steels with high impact toughness is extremely important to guarantee sufficiently the safe operation of the nuclear reactor. Usually low alloy CrMo steels enter service after the normalized and tempered treatment or annealed treatment with a mixed ferritebainite or full bainite microstructure. The G18CrMo2-6 steel is one of the most popular materials with the mixed microstructures of ferrite and bainite for the pressure vessel in nuclear industry due to its good impact toughness,high strength and good creep resistance. In this work, the influence of microstructures, including the parent phases and precipitates, on the impact toughness is investigated in detail. The experimental results show that the constituent of the parent phases, namely the ferrite, pearlite or bainite, is not the reason resulting in the ultra-low impact energy. The microstructure characterization implies that the morphology and the distribution of precipitates play the key role in controlling the impact toughness of the G18CrMo2-6 steel. The lower tempering temperatures result in the blocky martensite/austenite(M/A) island and lathy M3C carbides with the large particle size. The finely granular M3C carbides with the uniform distribution on the bainite matrix can be found at the higher tempering temperatures. As the tempering temperature increased, the Charpy absorbed energy at room temperature increased. After the tempering below 600 ℃, Charpy absorbed energy has the ultra-low value of 17 and 29 J. Generally speaking,the weak softening of matrix during the lower tempering temperature increases the accumulative residual stress at particle-ferrite interface. The other important factor should be attributed that the blocky M/A island and lathy M3C carbides result in the lower critical fracture stress of a particle-ferrite interface.

Five different basic manual metal arc welding electrodes, containing varying amounts of nickel (from 0 to 3.5%) were deposited in an all weld metal joint. Mechanical testing and microstructure examination was performed in the as deposited and heat treated conditions. The heat treatment was carried out at three different temperatures (930, 980, and 1030° C) for 20 min. The tensile strength was decreased by the heat treatment, but the magnitude of the decrease varied between the weld metals. The impact properties were also affected by the heat treatment. For impact properties, however, a decrease was found at low testing temperatures, whereas an increase was observed at higher testing temperatures. The decrease in tensile strength after normalisation, compared with the as deposited condition, is due to an increasing grain size and a decreasing dislocation content. The strength achieved by the different weld metals in the normalised condition can be explained by the variation in solid solution hardening resulting from differences in the alloying content.Two factors seemed to be especially important in determining the variations in impact properties between weld metals in the as deposited condition. The nitrogen content of the weld metals decreased the impact toughness, whereas increasing nickel content was associated with improved impact toughness. In the normalised condition, reduced at lower testing temperatures, because cleavage fracture started readily in the resulting coarser grains. Furthermore, traces of segregated bands of microphases probably acted as initiation sites for cleavage cracks. At higher testing temperatures, higher impact toughness was obtained, owing to the lower strength of the weld metals. One of the electrodes showed superior impact toughness values to the other electrodes, in both the as deposited and heat treated conditions. The main reason for the high toughness in the as deposited condition was the ability of this electrode to refine previously deposited beads to a high degree. The reason for the high toughness after normalising is still not certain, but it was noted that this weld metal had a very low oxygen content and also a comparatively low volume fraction of segregated microphases. These factors might be important in achieving the very high impact toughness observed.

Carbide-free bainite in medium carbon steel

In recent years, conductive hydrogels have received increasing attention as wearable electronics due to the electrochemical properties of conductive polymers combined with the softness of hydrogels. However, conventional hydrogels are complicated to prepare, require high temperature or UV radiation to trigger monomer polymerization, and are frozen at low temperatures, which seriously hinder the application of flexible wearable devices. In this paper, a conductive sensor integrating mechanical properties, adhesion, UV shielding, anti-dehydration, and anti-freeze was prepared based on Ca2+-initiated radical polymerization at room temperature using the synergy of sodium lignosulfonate, acrylamide (AM), and calcium chloride (CaCl2). Metal ions can activate ammonium persulfate to generate free radicals that allow rapid gelation of AM monomers at room temperature without external stimuli. Due to ionic cross-linking and non-covalent interaction, the hydrogels have good tensile properties (1153% elongation and 168 kPa tensile strength), high toughness (758 KJ·m-3), excellent adhesive properties (48.5 kPa), high ionic conductivity (7.2 mS·cm-1), and UV resistance (94.4%). CaCl2 can inhibit ice nucleation, so that the hydrogels have anti-dehydration and frost resistance properties and even at -80 °C can maintain flexibility, high conductivity, and adhesion. Assembled into a flexible sensor, it can sense various large and small movements such as compression, bending, and talking, which is a flexible sensing material with wide application prospects.

The microstructure evolution and variation of impact toughness in the heat-affected zone (HAZ) of X80 pipeline steel with different Nb content under different peak temperatures in the secondary thermal cycle were studied through welding thermal simulation, the Charpy impact test, EBSD analysis, SEM observation, and TEM observation in this study. The results indicate that when the peak temperatures of the second pass were lower than Ac1, both X80 pipeline steels had high impact toughness. For secondary peak temperatures in the range of Ac1 to Ac3, both X80 pipeline steels had the worst impact toughness, mainly due to the formation of massive blocky M-A constituents in chain form on grain boundaries. When the secondary peak temperatures were higher than Ac3, both X80 pipeline steels had excellent impact toughness. Smaller grain size and higher proportions of HAGBs can effectively improve the impact toughness. Meanwhile, high Nb X80 pipeline steel had higher impact absorption energy and smaller dispersion. Adding an appropriate amount of Nb to X80 pipeline steel can ensure the impact toughness of SCCGHAZ and SCGHAZ in welded joints.