Unstable Atoms Research Articles

Looking Inside the Human Body Using Radioactive Atoms

Positron emission tomography (PET) is a method for taking pictures of a disease inside of a sick person’s body, without having to cut them open. In PET imaging, a radioactive chemical called a radiotracer is injected into a patient. All radiotracers have two main parts: a part that targets the disease, and an unstable atom (radioisotope) that emits positive electrons (positrons) as it breaks down (decays). When a positron crashes into an electron, both are destroyed, and two particles of light emerge. Doctors can detect these radioactive signals and use them to create a 3D image of where the tracer (and the disease) is in the body. This article describes PET and PET radioisotopes in greater detail. We focus on fluorine-18, a radioisotope that makes up the “signaling part” of many important PET radiotracers.

In Situ Studies of the Oxide Structure and Oxide Growth on Single Crystal Platinum Surfaces

Understanding the Pt surface oxidation is of key importance for the development of durable oxygen reduction reaction catalysts as used in low temperature fuel cells. The formation of an ultra-thin surface oxide on Platinum electrodes is causing atomic-scale restructuring of the electrode surface and Pt dissolution, which promotes the degradation of the Pt catalyst. The surface restructuring can be attributed to a place-exchange process, where Pt surface atoms are extracted from the electrode and form an oxide layer atop the surface [1]. A detailed atomistic picture of the oxide growth and oxide structure previously only existed for the Pt(111) electrode [2].In this study, we have used High Energy Surface X-ray Diffraction (HESXRD) [3] to analyse the atomic-scale surface structure of Pt(111), Pt(110) and Pt(100) during oxide formation and reduction in 0.1 M HClO4 and 0.1 M H2SO4. These surfaces exhibit distinct differences in stability towards restructuring after potential cycles to the same upper potential limit. On Pt(111), almost no surface roughening can be observed, while Pt(100) and Pt(110) immediately degrade upon a single oxidation. To elucidate this difference we performed a detailed analysis of the crystal truncation rods (CTR) to determine the location of the Pt atoms in the oxide formed on Pt(100). During initial stages of oxide formation at potentials < 1.2 V, the Pt atoms are extracted from the surface layer and moved laterally away from their original lattice sites. The extraction of the first atom initiates the immediate extraction of a second atom, leading to the formation of oxide stripes on the surface. DFT calculations support this scenario and show that, differently from Pt(111), this mechanism produces unstable surface atoms at stripe ends that can dissolve during the oxidation as well as during the subsequent oxide reduction [4]. A saturation coverage of about 0.4 ML extracted Pt atoms in this stripe oxide is reached already at about 1.2 V, representing a surface that is fully covered with oxide stripes. Our recent analysis of the CTRs of the oxide structure at higher potentials (> 1.2 V), shows that oxide growth continues vertically by the formation of a second distinct layer of Pt atoms above the stripe oxide.

Nuclear medicine imaging in oral diseases: A review

Nuclear medicine is the discipline of medicine that deals with the use of radionuclides in research, diagnosis, and treatment. It works on molecular &amp; functional level and uses radiopharmaceuticals in its procedure helping in detection of lesions before morphologic change is evident. Radiopharmaceuticals also known as Radionuclides/ Radioisotopes are unstable atoms of a chemical element, actively emit radiation. These emitted radiations are absorbed by photomultiplier tube and reconstructed by a computer system followed by display of an image. The rationale of writing this article is to understand about Nuclear Medicine and its applications in oral diseases.

A DFT+U study about agglomeration of Au atoms on reduced surface of rutile TiO2 (110)

The sintering deactivates CO oxidation in a single Au catalyst. Understanding the mechanism of sintering at a reduced atmosphere seems important for improving sintering resistance. Here, we employ the first principle calculations to evaluate the barrier energy of Au atoms on reduced rutile TiO2 (110) surface and to demonstrate a favorable channel for their diffusion at an early stage in sintering. In the current DFT + U calculations, 16 structural configurations with oxygen vacancies and Au atoms are considered. This shows that Au atoms prefer to mobilize on fivefold-coordinated Ti (Ti5c) row rather than moving perpendicularly from this Ti5c row to a twofold-coordinated O (O2c) row. We regard a trap center involving a complex of Au‒oxygen vacancy on an O2c row as the initial nucleation site during sintering. It will capture the unstable Au atom on a Ti5c row, and hence, a highly stable Au dimer would be produced as the primary nucleation pattern.

In-situ investigation on the thermal decomposition of van der Waals MoO3

The van der Waals α-MoO3 is one of the most attracted two-dimensional metal oxides in opto-electronics Thermal stability is one of the key properties in device application. Here, the thermal decomposition of individual α-MoO3 nanosheet was investigated using in-situ microscope and Raman spectroscopy. It’s found that the nanosheet decomposes above 400 °C. Three decomposition behaviors, including void decomposition, edge decomposition and layer-by-layer decomposition were found. The Oa atom is the most unstable oxygen atom that causes a preferential decomposition along the [0 0 1] direction. Thermal stress accumulated in the [1 0 0] direction leads to a non-linear temperature dependent Raman shifting.

Structure-Dependence of the Atomic-Scale Mechanisms of Pt Electrooxidation and Dissolution

For current low-temperature hydrogen-oxygen fuel cells, as used e.g. in the upcoming generation of commercial fuel cell vehicles, platinum is still the catalyst of choice, especially for the cathode side. However, catalyst lifetime and performance remain a problem for large-scale commercialization. It has been known for some time that electrochemical oxidation and subsequent oxide reduction lead to irreversible structural changes as well platinum dissolution but the fundamental understanding of these complex processes is still rudimentary. A detailed atomistic picture of the steps by which these ultrathin oxide layers form existed up to now only for the close-packed Pt(111) surface [1]. Here, previous in situ studies by surface X-ray diffraction (SXRD) techniques established the precise locations of the first Pt atoms that move out of their lattice sites in a place-exchange process [2] and found good agreement with density functional theory (DFT) calculations [3]. Provided the potential is not too high, these atoms can move back to their original locations, but at higher potentials an irreversible restructuring of the surface occurs.To elucidate the role of the Pt surface structure, we performed in-depth comparative studies of Pt(111) and Pt(100) in perchloric acid solution by in situ SXRD, online inductively coupled plasma mass spectrometry (ICP-MS) and DFT [4]. Clear differences were found, which mirror the differences in the dissolution behavior of the two electrode surfaces (Figure 1a). Pt(100) not only start to dissolve at lower potential but its oxidation also immediately changes its surface structure in an irreversible manner. These observations demonstrate clearly that Pt dissolution is linked to the way Pt atoms are initially extracted from the surfaces during oxidation.For a better understanding of the extraction process on Pt(100), we performed surface diffraction studies at ESRF ID31 with very high photon energies of 70 keV (HESXRD) [5]. This technique was employed for the first time to a solid-liquid interface and proofed to be indispensable for clarifying the oxide’s structure. The oxidation-induced changes, exemplified in figure 1b for one out of twelve simultaneously measured crystal truncation rods, can be unambiguously assigned to a process in which the extracted Pt atom moves laterally away from its original site. This initiates the immediate extraction of a second atom, leading to the formation of atomic oxide stripes on the surface (see figure 1c). DFT calculations support this scenario and show that, differently from Pt(111), this mechanism produces unstable surface atoms at stripe ends that can dissolve during the oxidation as well as during the subsequent oxide reduction. Consequently, the extraction process on Pt(100) is irreversible from its very onset.These results show a high sensitivity of Pt electrocatalyst oxidation and degradation to the precise surface structure. Rational strategies for the design of catalysts with improved stability will have to take the different mechanisms into account.[1] J. Drnec, D.A. Harrington, O.M. Magnussen, Curr. Op. Electrochem., 4, 69-75 (2017)[2] M. Ruge, et al., J. Electrochem. Soc., 164, H608-H614 (2017)[3] M. J. Eslamibidgoli,, M. H. Eikerling, Electrocatalysis, 7, 345–354 (2016)[4] T. Fuchs, et al., Nat. Catal., 3, 754-761 (2020)[5] J. Gustafson, et al., Science, 343, 758–761 (2014) Figure 1. (a) correlation between Pt(hkl) dissolution and restructuring behavior in 0.1 M HClO4. (b) Example of Pt(100) crystal truncation rod changes with increasing oxidation, measured by in situ high-energy surface X-ray diffraction. (c) Pt extraction mechanisms, obtained from DFT calculations (adapted from T. Fuchs, et al., Nat. Catal., 3, 754 (2020)). Figure 1

Synthesis of Lanthanum Orotate and its Application as PVC Thermal Stabilizer

The structure of basic lanthanum orotate (LaOr) were characterized by elemental analysis and infrared spectroscopy. The thermal stability of polyvinyl chloride (PVC) was further studied by Congo red method, oven discoloration method and thermogravimetric analysis. The results showed that LaOr could prolong the oven discoloration time of PVC, and the color was not completely blackened until 120 min. It has a good synergetic effect with dibenzoyl methane (DBM), and the best effect is achieved when LaOr/DBM ratio is 1.8/1.2. The thermal decomposition kinetics experiment showed that adding DBM can effectively improve the activation energy of PVC/LaOr. The stabilization mechanism of PVC was studied by absorbing HCl method and infrared spectroscopy. The results showed that LaOr could not only replace the unstable chlorine atoms on PVC, but also promote the long-term thermal stability of PVC by absorbing HCl.

Molecular dynamics study on atomic elastic stiffness at mode I crack along bi-metal interface.

Propagation of mode I crack along bi-metal (001) interfaces of Fe/W, Fe/Ni, Fe/Co and Ti/Mg is simulated by molecular dynamics and discussed with the eigenvalue/vector of the atomic elastic stiffness, [Formula: see text], and surface energy. The crack does not propagate at the interface but in the adjacent phase of smaller surface energy, except in Fe/Ni. The 1st eigenvalue ηa(1), or the solution of [Formula: see text] of each atom, clarifies the difference of 'soft/hard' of both phases at the onset of crack propagation. In the case of Fe/Ni, the ηa(1) of Ni atoms remarkably decreases in the Fe/Ni bi-metal structure, even though Ni has higher ηa(1) than Fe at no-load perfect lattices. Thus the rupture occurs in the Ni side even though the Ni has slightly higher (001) surface energy than Fe. Deformation modes at the crack propagation are also visualized by the eigenvector of ηa(1) < 0 unstable atoms. This article is part of the theme issue 'Fracture dynamics of solid materials: from particles to the globe'.

Coal-derived synthetic graphite with high specific capacity and excellent cyclic stability as anode material for lithium-ion batteries

The synthetic graphite with higher specific capacity and superior cyclic lifespan is prepared by high temperature graphitization of anthracite coupled with effective catalyst. In the process of graphitization, the thermodynamically unstable carbon atoms orderly convert from disordered structure to graphite crystal structure by thermal activation. However, it is necessary for the graphitization process at high temperature above 2800 °C. The slow reaction speed, low conversion rate, and unmanageable temperature result in a low graphitization degree. Also, B2O3 as catalyst is beneficial to the directional growth of the aromatic layer in graphite structure, which reduces the cross-linking of the aromatic layer and enhances its coplanarity, as well as reduces energy barrier of graphitization and accelerates the formation of graphite phase. When served as anode material for lithium-ion batteries, the material delivers high delithiation capacity of 369 mA h g−1 with first coulomb efficiency (FCE) of 85.3% at 0.05C and even 160 mA h g−1 at 3C. Moreover, at the current density of 0.5 C, the initial capacity still maintains more than 300 mA h g−1 accompanied with almost 98% capacity after 500 cycles. Often, more than 80% of capacity retention at 2 C enables it more competitive and attractive in the fields of anode materials. By matching the graphite as anode and commercial LiFePO4 as cathode, a full battery is assembled, which still remains the capacity of 93% after nearly 400 cycles, showing cyclic stability of the material. The research provides a direction for the mass production of graphite with coal.

The role of scientific research on nuclear radiation waste management and preserving environment

On the level of this article, we deal with nuclear radiation (and their residues), which is defined as a physical phenomenon and strong atomic activity that occurs in unstable atoms of elements. We are interested in studying radiation as the emission or diffusion of energy into space in the form of electromagnetic waves or particles. The scientist Fermi (1934 AD) is among the first to present scientific research in this field. Radioisotopes are considered one of the most prominent discoveries of modern science and based on the importance of the topic, scientists and researchers searched for methods and techniques to facilitate the implementation of practical applications for radiation measurement, and among those methods a specialized program was used to simulate radiation dose (digital simulation in a computer through the use of an imaginary model of the radiometric process with technology Monte Carlo using code (Geant 4). We have also highlighted the views of researchers and specialists in the area of disposal of radioactive waste, relying on a field study and a comparison of some of the currently adopted techniques to get rid of the negative consequences that each unreasonable (reckless) management and measure of this radioactive waste may have Among the most prominent results we have reached is highlighting the weakness of dealing with this topic and not giving it the right to research and scientific achievements carried out by researchers, which increases the complexity of the situation and from which it is difficult to control the problem in the future.

An interacting fermion-antifermion pair in the spacetime background generated by static cosmic string

We consider a general relativistic fermion antifermion pair that they interact via an attractive Coulomb type interparticle interaction potential in the 2+1 dimensional spacetime background spanned by cosmic string. By performing an exact solution of the corresponding fully-covariant two body Dirac Coulomb type equation we obtain an energy spectrum that depends on angular deficit parameter of the static cosmic string spacetime background for such a composite system. We arrive that the influence of cosmic string spacetime topology on the binding energy of Positronium-like atoms can be seen in all order of the coupling strength constant, even in the well-known non-relativistic binding energy term (∝αc2). We obtain that the angular deficit of the static cosmic string spacetime background causes a screening effect. For a predicted value of angular deficit parameter, α∼1−10−6, we apply the obtained result to an ortho-positronium, which is an unstable atom formed by an electron and its antimatter counterpart a positron, and then we determine the shift in the ground state binding energy level as 27,2μeV. We also arrive that, in principle, the shift in ground state binding energy of ortho-positronium can be measured even for α∼1−10−11 value with current techniques in use today. Moreover, this also gives us an opportunity to determine the altered total annihilation energy transmitted by the annihilation photons. The yields also impose that the total lifetime of an ortho-positronium can be changed by the topological feature of static cosmic string spacetime background. In principle, we show that an ortho-positronium system has a potential to prove the existence of such a spacetime background.

Structure dependency of the atomic-scale mechanisms of platinum electro-oxidation and dissolution

Platinum dissolution and restructuring due to surface oxidation are primary degradation mechanisms that limit the lifetime of platinum-based electrocatalysts for electrochemical energy conversion. Here, we have studied well-defined Pt(100) and Pt(111) electrode surfaces by in situ high-energy surface X-ray diffraction, online inductively coupled plasma mass spectrometry and density functional theory calculations to elucidate the atomic-scale mechanisms of these processes. The locations of the extracted platinum atoms after Pt(100) oxidation reveal distinct differences from the Pt(111) case, which explains the different surface stability. The evolution of a specific oxide stripe structure on Pt(100) produces unstable surface atoms that are prone to dissolution and restructuring, leading to one order of magnitude higher dissolution rates. Platinum dissolution and restructuring due to surface oxidation are primary degradation mechanisms of platinum-based electrocatalysts. Now, stark differences are reported in the mechanism for the oxidative extraction of platinum atoms on (111) and (100) single crystals, providing a detailed explanation for the enhanced dissolution on the latter surface.

The synergistic effects study between metal oxides and graphene on far-infrared emission performance

Materials with high far-infrared (FIR) emissivity are quiet promising in modern medical care field, owing to its accelerating effects to blood circulation and metabolism. In this work, we synthesized two serials composites: MnO2/graphene nanoplate (GNPs) and Fe2O3/GNPs via in situ hydrothermal process. Positive synergistic effects on FIR emission were shown between either MnO2 or Fe2O3 and GNPs. In particular, MnO2/GNPs (2%) showed a super high FIR emissivity of 0.981 compared with pristine MnO2 (0.940) and GNPs (0.878) in the wavelength of 8–14 µm. The FIR emissivity of Fe2O3/GNPs (1%) was up to 0.953 that was much higher than those of pristine Fe2O3 (0.877) and GNPs as well. Benefiting from the characteristics of graphene such as large specific surface, lightweight and thin-layer, MnO2 and Fe2O3 nanocrystals grew on graphene surface and formed different morphologies. A coralloid-like morphology was formed to MnO2/GNPs (2%), suggesting a highly porous surface that meant more unstable atoms or molecules were exposed. The morphologies of metal oxide/GNPs were thought to relate with the good synergistic effects between GNPs and metal oxides. Therefore, this work provides that metal oxides/graphene composites have promising application for high FIR emission materials.

The Crystallinity of Apatite in Contact with Metamict Pyrochlore from the Silver Crater Mine, ON, Canada

The purpose of this work is to evaluate the long-term effects of radiation on the structure of naturally occurring apatite in the hope of assessing its potential for use as a solid nuclear waste form for actinide sequestration over geologically relevant timescales. When a crystal is exposed to radioactivity from unstable constituent atoms undergoing decay, the crystal’s structure may become damaged. Crystalline materials rendered partially or wholly amorphous in this way are deemed “partially metamict” or “metamict” respectively. Intimate proximity of a non-radioactive mineral to a radioactive one may also cause damage in the former, evident, for example, in pleochroic haloes surrounding zircon inclusions in micas. Radiation damage may be repaired through the process of annealing. Experimental evidence suggests that apatite may anneal during alpha particle bombardment (termed “self-annealing”), which, combined with a low solubility in aqueous fluids and propensity to incorporate actinide elements, makes this mineral a promising phase for nuclear waste storage. Apatite evaluated in this study occurs in a Grenville-aged crustal carbonatite at the Silver Crater Mine in direct contact with U-bearing pyrochlore (var. betafite)—a highly radioactive mineral. Stable isotope analyses of calcite from the carbonatite yield δ18O and δ13C consistent with other similar deposits in the Grenville Province. Although apatite and betafite imaged using cathodoluminescence (CL) show textures indicative of fracture-controlled alteration, Pb isotope analyses of betafite from the Silver Crater Mine reported in previous work are consistent with a model of long term Pb loss from diffusion, suggesting the alteration was not recent. Thus, it is interpreted that these minerals remained juxtaposed with no further metamorphic overprint for ≈1.0 Ga, and therefore provide an ideal opportunity to study the effects of natural, actinide-sourced radiation on the apatite structure over long timescales. Through broad and focused X-ray beam analyses and electron backscatter diffraction (EBSD) mapping, the pyrochlore is shown to be completely metamict—exhibiting no discernible diffraction associated with crystallinity. Meanwhile, apatite evaluated with these methods is confirmed to be highly crystalline with no detectable radiation damage. However, the depth of α-decay damage is not well-understood, with reported depths ranging from tens of microns to just a few nanometers. EBSD, a surface sensitive technique, was therefore used to evaluate the crystallinity of apatite surfaces which had been in direct contact with radioactive pyrochlore, and the entire volume of small apatite crystals whose cores may have received significant radiation doses. The EBSD results demonstrate that apatite remains crystalline, as derived from sharp and correctly-indexed Kikuchi patterns, even on surfaces in direct contact with a highly radioactive source for prolonged periods in natural systems.

Selective single-atom electrocatalysts: a review with a focus on metal-doped covalent triazine frameworks.

Single-atom electrocatalysts (SACs), which comprise singly isolated metal sites supported on heterogeneous substrates, have attracted considerable recent attention as next-generation electrocatalysts for various key reactions from the viewpoint of the environment and energy. Not only electrocatalytic activity but also selectivity can be precisely tuned via the construction of SACs with a defined coordination structure, such as homogeneous organometallics. Covalent organic frameworks (COFs) are promising supports for single-atom sites with designed coordination environments due to their unique physicochemical properties, which include porous structures, robustness, a wide range of possible designs, and abundant heteroatoms to coordinate single-metal sites. The rigid frameworks of COFs can hold unstable single-metal atoms, such as coordinatively unsaturated sites or easily aggregated Pt-group metals, which exhibit unique electrocatalytic selectivity. This minireview summarizes recent advances in the selective reactions catalysed by SACs, mainly those supported on triazine-based COFs.

Non‐Singular Black Holes Interiors Need Physics Beyond the Standard Model

AbstractThe composition as well as the very existence of the interior of a Schwarzschild black hole (BH) remains at the forefront of interesting, open problems in fundamental physics. To address this issue, we turn to Hawking's “principle of ignorance”, which says that, for an observer with limited information about a physical system, all descriptions that are consistent with known physics are equally valid. We compare three different observers who view the BH from the outside and agree on the external Schwarzschild geometry. First, the modernist, who accepts the classical BH as the final state of gravitational collapse, the singularity theorems that underlie this premise and the central singularity that the theorems predict. The modernist is willing to describe matter in terms of quantum fields in curved space but insists on (semi)classical gravity. Second is the skeptic, who wishes to evade any singular behavior by finding a loophole to the singularity theorems within the realm of classical general relativity (GR). The third is a postmodernist who similarly wants to circumvent the singularity theorems but is willing to invoke exotic quantum physics in the gravitational and/or matter sector to do so. The postmodern view suggests that the uncertainty principle can stabilize a classically singular BH in a similar manner to the stabilization of the classically unstable hydrogen atom: Strong quantum effects in the matter and gravitational sectors resolve the would‐be singularity over horizon‐sized length scales. The postmodern picture then requires a significant departure from (semi)classical gravity, as well as some exotic matter beyond the standard model of particle physics (SM). We find that only the postmodern framework is consistent with what is known so far about BH physics and conclude that a valid description of the BH interior needs matter beyond the SM and gravitational physics beyond (semi)classical GR.

The application of a drift model of fission gas transport to unstable gas release in irradiated uranium dioxide

A previous paper has discussed the application to stable fission gas release of an enhanced Fick's Law transport process which also includes a so-called drift term arising from gas atom drag by moving dislocations. The new transport law was shown to be effective at describing stable fission gas release from the onset of grain-boundary tunnel interlinkage to the appearance of high burnup fuel restructuring. In the present work this law is applied to the release of unstable fission gases and is shown to be incapable of explaining the observed data. An explanation for this anomaly has been sought in the PIE of dislocations in irradiated fuel. The ultimate rationale focuses on the recognition not only that successfully released unstable gas atoms are created in the surface region of the fuel grain but also that the solute drag mechanism conspires to favour gas atom motion in the depth of the fuel grain rather than the surface.

Development and Investigation of Lanthanum Sulfadiazine with Calcium Stearate and Epoxidised Soyabean Oil as Complex Thermal Stabilizers for Stabilizing Poly(vinyl chloride).

Lanthanum sulfadiazine (LaSD) was synthesized from sulfadiazine and lanthanum nitrate using water as solvent under alkaline conditions, and was used as a novel rare earth thermal stabilizer to stabilize poly(vinyl chloride) (PVC). The structure of LaSD was characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR) and thermo- gravimetric analysis (TGA). The influence of lanthanum sulfadiazine with calcium stearate (CaSt2) and epoxidized soybean oil (ESBO) on stabilizing PVC was studied by using the Congo red test, oven discoloration test, UV-vis spectroscopy and thermal decomposition kinetics. The results showed that the addition of LaSD as a thermal stabilizer can significantly improve the initial whiteness and long-term stability of PVC. In addition, the synergies between LaSD, ESBO, and CaSt2 can provide outstanding improvement in the long-term thermal stability of PVC. When the ratio of LaSD/ESBO/CaSt2 is 1.8/0.6/0.6, its thermal stability time is 2193 s which is the best state for stabilizing PVC. Furthermore, comparing the reaction energy (Ea) and the variations in the conjugate double bond concentration in PVC samples, the order of thermal stability of PVC was PVC/LaSD/ESBO/CaSt2 > PVC/LaSD/ESBO > PVC/LaSD. The thermal stability mechanism of LaSD on PVC was studied by the AgCl precipitation method and FTIR spectrum. The results showed that the action of LaSD on PVC was achieved through replacing unstable chlorine atoms and absorbing hydrogen chloride.

Investigation of lanthanum trioxypurine with zinc stearate and pentaerythritol as complex thermal stabilizers for poly(vinyl chloride)

Lanthanum trioxypurine (LaTr) was triumphantly synthesized by reacting trioxypurine and lanthanum nitrate at neutral condition and was characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The thermal stability effect of LaTr with its assistant thermal stabilizers about zinc stearate (ZnSt2) and pentaerythritol (Pe) on poly(vinyl chloride) (PVC) was investigated by Congo red test, discoloration test, UV–vis spectroscopy test, and thermal decomposition kinetics. The results showed that the addition of LaTr as thermal stabilizer could significantly enhance static stability time and long‐term stability of PVC. It could be mainly attributed to the anions in the structure of LaTr, could efficiently absorb the hydrogen chloride released by PVC, and have ability to replace unstable chlorine atoms on structure of PVC. Moreover, the mixing of LaTr, Pe, and ZnSt2 could reveal an excellent synergistic effect and both promote the initial color and the long‐term thermal stability of PVC. The thermal stability of PVC reached the optimal state when the ratio of LaTr/Pe/ZnSt2 was 1.8/0.6/0.6. In addition, compared with the reaction energy Ea and UV–vis spectroscopy test's result of PVC samples, the order of PVC's thermal stability was PVC/LaTr/Pe/ZnSt2 &gt; PVC/LaTr/Pe &gt; PVC/LaTr. The result was further ascertained that LaTr/Pe/ZnSt2 showed excellent synergistic effect and could be used as an excellent complex thermal stabilizer for PVC. J. VINYL ADDIT. TECHNOL., 25:347–358, 2019. © 2019 Society of Plastics Engineers

Synthesis and Study of Zinc Orotate and Its Synergistic Effect with Commercial Stabilizers for Stabilizing Poly(Vinyl Chloride).

Zinc orotate (ZnOr2), which is a new kind of poly(vinyl chloride) (PVC) stabilizer, is prepared in this work through the precipitation method, and its impact on the thermal stability of PVC is measured by thermogravimetric analysis (TG), Congo red test, and discoloration test. The results exhibit that the thermal stability of PVC is positively enhanced after the addition of ZnOr2. In contrast with a commercial thermal stabilizer, zinc stearate (ZnSt2), a noteworthy improvement was observed that ZnOr2 could postpone the “zinc burning” of PVC. This is principally ascribed to the Or anion in the structure of ZnOr2 being able to absorb the HCl released by PVC, and to supersede unstable chlorine atoms in the structure of PVC. In addition, blending ZnOr2 with calcium stearate (CaSt2) in diverse mass ratios can significantly accelerate the thermal stability of PVC. Optimum performance was achieved with a CaSt2:ZnOr2 ratio of 1.8:1.2. Moreover, an outstanding synergistic effect can be observed when CaSt2/ZnOr2 is coupled with other commercial auxiliary stabilizers. The initial color and long-term stability of PVC including CaSt2/ZnOr2 is significantly increased when pentaerythritol (PER) is added, while dibenzoylmethane (DBM) can only improve its long-term thermal stability.