Effects of Organic Sulfur and Phosphor Compounds Used as Antioxidants on the Thermal Behavior of Nitrocellulose and its Decomposition Mechanism

The effects of 3‐dodecylsulfanyl‐propionic acid 3‐(3‐dodecylsulfanyl‐propionyloxy)‐2,2‐bis‐(3‐dodecylsulfanyl‐propionyl‐oxymethyl)‐propyl ester (SO), 3,9‐bis‐octadecyloxy‐2,4,8,10‐tetraoxa‐3,9‐diphospha‐spiro[5,5]undecane (POf), and 3,9‐bis‐(2,6‐di‐tert‐butyl‐4‐methyl‐phenoxy)‐2,4,8,10‐tetraoxa‐3,9‐diphospha‐spiro[5,5]undecane (POp), which are used as antioxidants for polymers, on the degradation of nitrocellulose (NC) were investigated under isothermal storage conditions at 393 K with a microcalorimeter. The result indicated that SO/NC and POf/NC accelerated the heat release when compared with NC without an antioxidant, whereas the heat release behavior of NC/POp was similar to that of NC without an antioxidant. In the case of SO/NC and POf/NC, the heat release was observed in the presence of O₂, whereas it was not observed in a N₂ atmosphere. The SO content in SO/NC and PO content in POf/NC increased with the storage time. According to this behavior, it can be explained that sulfuric acid or phosphoric acid, which originates from SO or POf, accelerates the autoxidation of NC.     

Thermal Behavior of Nitrocellulose with Inorganic Salts and their Mechanistic Action

In this study, we investigated the effects of inorganic salts on the stability of NC and its reaction mechanism. Under isothermal conditions at 120 °C in an O₂ atmosphere, the induction time period for NC heat release was prolonged in the presence of Li₂CO₃, Na₂CO₃, CaCO₃, Mg(OH)₂, Ca(OH)₂, and MgO, all of which produce alkaline saturated solutions with a pH value of 10–12. In addition, the induction time period depended on this pH value. This suggests that these salts stabilized NC by neutralizing acids that would otherwise accelerate the hydrolysis of the O‐NO₂ bond. However, Sr(OH)₂ ⋅ 8H₂O and K₂CO₃, which produce strongly alkaline saturated solutions with pH>13, decreased the induction time period. It is possible that these strong bases caused alkaline decomposition of NC. In addition, for Sr(OH)₂ ⋅ 8H₂O, the released water of crystallization appeared to be related to NC destabilization. SrCO₃, NaHCO₃, K₂SO₄, CaSO₄, ZnSO₄, NaCl, CaCl₂, AgCl, and NaNO₂, which produce near‐neutral saturated solutions, slightly decreased the NC induction time period. The NC induction time period with these salts depended upon the solubility of the added salt. This may indicate that in the presence of these inorganic salts, the boiling point of water is increased, which reduces the vaporization of water from NC and thus accelerates the hydrolysis of NC.     

抗氧剂1010生产中加成反应工艺条件的优化

对由 2 ,6 -二叔丁基苯酚和丙烯酸甲酯进行加成反应合成 3,5甲酯的工艺条件进行了研究 ,分析讨论了反应物配比、加料方式、反应温度及反应时间等因素对加成反应的影响 ,优化了工艺条件。结果表明 ,新工艺条件下生产的 3,5 -二叔丁基 - 4羟基苯丙酸甲酯产品质量为优级品     

紫外线吸收剂UV-326的合成

4-氯 - 2 -硝基苯胺 ( 1 )用亚硝酸钠 ( 2 )和硫酸重氮化后与 2 -特丁基 - 4-甲基苯酚 ( 3)反应制成 2 -硝基 - 4-氯 - 2′-羟基 - 3′-特丁基 - 5′-甲基偶氮苯 ( 4 )。其摩尔比为 ( 1 )∶ ( 2 )∶ ( 3) =1∶ 1 .0 5∶ 1 .1 0 ,( 4 )用硫化钠还原制成 2 - ( 2′-羟基 - 3′-特丁基 - 5′-甲基苯基 - ) - 5-氯苯并三唑 N-氧化物 ( 5) ,( 5)用锌粉还原制成最终产品 2 - ( 2′-羟基 - 3′-特丁基 - 5′-甲基苯基 ) - 5-氯苯并三唑 ( 6) ,亦即 UV- 32 6。光老化试验表明它是聚烯烃、ABS、聚酯和其他树脂的优良的光稳定剂。已建成 2 0 0 t/a工业装置并投入生产。     

Polymerization of methyl methacrylate catalyzed by macromolecule–copper (II) complex in sodium sulfite aqueous system

Vinyl polymerization initiated by a copper complex immobilized on a novel polymer and characterization has been studied. Monomer, 4‐aldehyde‐3‐hydroxy phenyl acrylate (Ahpa), and its homopolymer, poly(4‐aldehyde‐3‐hydroxy phenyl acrylate) (PAhpa), were synthesized and characterized using IR, elemental analysis, ¹H NMR, TOF MS, etc. The side chain of the polymer can further coordinate with transition metal ions. Its polymeric Cu(II) complex in Na₂SO₃ system is proved to be another useful catalyst in polymerization of methyl methacrylate (MMA) at room temperature. The obtained poly(methyl methacrylate) (PMMA) is similar to those determined by conventional free radical polymerization at the same conditions. Moreover, the catalytic mechanism studied was a “Coordination Hydrogen‐Transfer” process, which is different from that of CuCl₂/Na₂SO₃ system, but analogous with that of PVAm‐Cu(II)/Na₂SO₃ (PVAm = polyvinylamine) system, was speculated and testified. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1285–1290, 2007     

Solid‐phase preparation method of silica‐supported 2,2′‐methylenebis(6‐tert‐butyl‐4‐methyl‐phenol) and its antioxidative behavior in styrene‐butadiene rubber

A solid‐phase preparation method is applied to the synthesis of a novel supported rubber antioxidant, silica–supported 2,2′‐methylenebis(6‐tert‐butyl‐4‐methyl‐phenol) (SiO₂‐2246), by directly reacting 2,2′‐methylenebis (6‐tert‐butyl‐4‐methyl‐phenol)(antioxidant 2246) with silica. FTIR, Raman spectroscopy and TGA confirm that the antioxidant 2246 is chemically bonded on the surface of the silica particles. The SEM observation shows that the SiO₂‐2246 is homogeneously dispersed in the styrene‐butadiene rubber (SBR) matrix. The results of the apparent activation energy and the attenuated total reflectance infrared spectrometry indicate that the antioxidative efficiency of the SiO₂‐2246 in SBR is superior to the corresponding low‐molecular‐weight 2246. The thermal oxidative stability of the SBR/SiO₂‐2246 composites is much higher than that of the SBR/SiO₂/2246 composites by comparing their mechanical properties retentions and crosslinking densities. Additionally, the advantages of SiO₂‐2246 also include low migration, low volatility, and low pollution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43014.     

Effect of antiaging agents on the outdoor natural weathering of bamboo powder/polypropylene foamed composites

The effect of outdoor natural weathering on the properties of injection molded 33 wt% bamboo powder (BP)/polypropylene (PP) foamed composites with and without the antioxidant and hindered amine light stabilizers (HALS) were investigated. The composites containing the antiaging agents had higher color stability, slightly greater retentions of flexural modulus, tensile and notched impact strengths, higher creep resistance, and better rheological stability than the reference composite. The antiaging agents of pentaerythritol tetrakis(3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate) and poly‐(n‐hydroxyethyl‐2,2,6,6‐tetramethyl‐4‐hydroxy‐piperidyl succinate) had more beneficial effect than n‐octadecyl‐β‐(4‐hydroxy‐3,5‐di‐tert‐butyl‐phenyl)‐propionate and bis(2,2,6,6‐tetramethyl‐4‐piperidinyl)sebacate. After 12 months of exposure, △E^* decreased from 22.8 of the reference composite to 9.9 of the composite with the antiaging agents. Rheological behavior results indicated that the storage modulus, complex viscosity, and non‐Newtonian fluid index of composites containing the antiaging agents were slightly increased. Natural weathering caused less decreases in the storage and loss moduli, crossover modulus, relaxation time, and average molecular weight for composites containing the antiaging agents than those for the reference composite. Environmental scanning electron microscopy (ESEM) observation confirmed the improved surface durability for composites containing the antiaging agents. J. VINYL ADDIT. TECHNOL., 22:311–319, 2016. © 2014 Society of Plastics Engineers     

Synthesis of cis‐1,4‐polyisoprene with Al‐Ti catalysts modified by different electron donor reagent

The preparation of the high cis ?1,4‐polyisoprene by Ziegler‐Natta catalysis system was studied. The effect of Al‐Ti catalysts modified by ethers with different structures which are different electron donor reagent on polymerization of isoprene has been mainly investigated. By the measurement method of the monomer conversion, FTIR, and ¹H NMR spectroscopy, the influence of, respectively, added diphenyl ether, anisole, dibutyl ether, or methyl tert ‐butyl methyl ether as a third active component on the heterogeneous TiCl₄‐Al(i ‐Bu)₃‐ether catalyst activity and microstructure of synthetic polyisoprene was analyzed. By the adding of diphenyl ether or dibutyl ether, the process of prefabricated heterogeneous catalyst is quickly and catalyst particle quantity is large. The polymerization conversion is high and the microstructure cis ?1,4 content of the resulting polymer can reach 92%. But Al(i ‐Bu)₃ added anisole or methyl tert ‐butyl methyl ether hard to cooperate with TiCl₄. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44357.     

杯芳烃／聚丙烯共混体系耐热氧性能的研究

合成了对叔丁基杯[4]、杯[6]、杯[8]芳烃,并用热重法和烘箱老化评价了共混体系的耐热氧性能。结果表明,杯芳烃能明显提高聚丙烯的耐热氧性能,其耐热氧能力为：对叔丁基杯[6]芳烃＞对叔丁基杯[4]＜2,6－二叔丁基－4－甲基苯酚。     

Efficient Inhibition of Telomerase by Nickel–Salophen Complexes

Four nickel(II)–salophen complexes containing alkyl‐imidazolium chains connected at the ortho or meta positions were prepared: N,N′‐bis(2‐hydroxy‐4‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)phenylenediamine ( 1 ), N,N′‐bis(2‐hydroxy‐3‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)phenylenediamine ( 2 ), N,N′‐bis(2‐hydroxy‐3‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)methyl‐3H‐imidazol‐1‐iumphenylenediamine ( 3 ), and N,N′‐bis(2‐hydroxy‐4‐methyl‐3H‐imidazol‐1‐iumbenzylideneamino)methyl‐3H‐imidazol‐1‐iumphenylenediamine ( 4 ). They protect G‐quadruplex DNA (G₄‐DNA) against thermal denaturation and show K_A values in the range of 7.4×10⁵ to 4×10⁷ m ^?1 for G₄‐DNA models. Complex 4 exhibits an IC₅₀ value of 70 nm for telomerase inhibition.     

Para‐substituted 1‐Phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolones as Selective Extractants for Vanadium(V) from Acidic Chloride Solutions

Abstract

Para‐substituted 4‐aroyl derivatives of 1‐phenyl‐3‐methyl‐5‐pyrazolones (HX), namely, 1‐phenyl‐3‐methyl‐4‐(4‐fluorobenzoyl)‐5‐pyrazolone (HPMFBP) and 1‐phenyl‐3‐methyl‐4‐(4‐toluoyl)‐5‐pyrazolone (HPMTP) were synthesized and examined with regard to the extraction behavior of multivalent metal ions such as magnesium(II), aluminum(III), titanium(IV), vanadium(V), chromium(III), manganese(II), iron(II), and iron(III) that are present in titania waste chloride liquors. For comparison, studies have also been carried out with 1‐phenyl‐3‐methyl‐4‐benzoyl‐5‐pyrazolone (HPMBP). The results demonstrate that vanadium(V) and iron(III) are extracted into chloroform with 4‐aroyl‐5‐pyrazolones as VO₂X · HX and FeX₃, respectively. On the other hand, magnesium(II), aluminum(III), titanium(IV), chromium(III), manganese(II), and iron(II) were not found to be extracted into the organic phase. The equilibrium constants of vanadium(V) and iron(III) with various 4‐aroyl‐5‐pyrazolones follow the order HPMFBP>HPMBP>HPMTP, which is in accordance with their pKa values. The selectivity between vanadium(V) and iron(III) increases with increasing hydrochloric acid concentration. Further, it is clear from the results that iron(III) is not getting extracted above 1.0 mol dm^?3 hydrochloric acid solution. The electronic and IR spectra of the extracted complexes of vanadium(V) and iron(III) were used to further clarify the nature of the extracted complexes. The potential of these reagents for the selective extraction and separation of vanadium(V) from titania waste chloride liquors has also been discussed.     

Asymmetric Sharpless epoxidation of 13S‐hydroxy‐ 9Z, 11E‐octadecadienoic acid (13S‐HODE)

The asymmetric Sharpless epoxidation of methyl 13S‐hydroxy‐9Z, 11E‐octadeca‐dienoate (13S‐HODE, 1 ) with tert‐butyl hydroperoxide (TBHP) catalysed by titanium tetraisopropoxide {Ti(ⁱOPr)₄} in the presence of L(+)‐diisopropyl tartrate (L‐DIPT) gave methyl 13S‐hydroxy‐11S, 12S‐epoxy‐9Z‐octadecenoate 2 (erythro isomer) in 84% diastereomeric excess (de). The epoxidation of 1 with TBHP catalysed by Ti(ⁱOPr)₄ in the presence of D(‐)‐DIPT yielded methyl 13S‐hydroxy‐11RR12R‐epoxy‐9Z‐octadecenoate (threo isomer) 3 in 76% de.     

Vanadium‐Catalyzed Selective Oxidation of Alcohols to Aldehydes and Ketones with tert‐Butyl Hydroperoxide

The oxidation of alcohols to aldehydes and ketones has been described using silica‐supported vanadium(IV ) oxide (V/SiO₂, 1 ) in the presence of tert‐butyl hydroperoxide in tert‐butyl alcohol at ambient temperature with quantitative yields. The procedure is simple, efficient and environmentally benign.     

Evaluation of the Acute Toxicity and Genotoxicity of Orange,Red, Violet and Yellow Pyrotechnic Smokes In Vitro

The acute toxicity and the genotoxicity of four colored smokes were studied by an in vitro method based on the exposure of human bronchial epithelial cell cultures to the smokes. All smoke formulations consisted of the oxidizer fuel mixture (potassium chlorate/lactose), talcum and the following dyes: 1,4‐dihydroxy anthraquinone (orange), 1‐(p‐tolylamino)‐4‐hydroxy anthraquinone (violet), 1‐methylamino anthraquinone (red) and 4,4′‐methylidyne‐bis‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one (yellow). The experiments were carried out in a laboratory scale chamber and in a large container. The toxicity was compared to that of hexachloroethane (HC)‐based reference smoke with known toxicity. All the colored smokes displayed acute toxicity. The order of toxicity in the laboratory scale tests was orange>violet≈red>HC>yellow and in the container tests orange>violet≈yellow>red. The orange smoke appeared genotoxic in all the tests. With the yellow and the violet smokes, the genotoxicity could not be totally excluded. The red smoke showed evidence of weak genotoxicity only in one test series at the highest concentration level.     

Reusable Chiral Dicationic Chromium(III) Salen Catalysts for Aminolytic Kinetic Resolution of trans‐Epoxides

A series of new recyclable chiral dicationic chromium(III) salen complexes 1 – 10 bearing different substituents, viz., hydrogen, methyl, tert‐butyl, triphenylphosphinomethyl, triethylaminomethyl, methylimidazolium, methylpyridinium, methyl‐N,N‐dimethylpyridinium at the 3,3′‐ and 5,5′‐ positions of the salen unit with (1S,2S)‐(+)‐1,2‐diaminocyclohexane, (1S,2S)‐(−)‐1,2‐diphenyl‐1,2‐diaminoethane, and (S)‐(−)‐1,1′‐binaphthyl‐2,2′‐diamine collars have been synthesized and characterized by various physico‐chemical methods. These complexes were used as catalysts for the highly enantioselective aminolytic kinetic resolution of racemic trans‐epoxides with different anilines as nucleophiles at room temperature. With the use of catalyst 3 , anti‐β‐amino alcohols were obtained in excellent yields (>99% with respect to the nucleophile) and enantioselectivities (ee>99%) with the concomitant recovery of corresponding epoxides in high optical purity (ee up to >99%) and quantitative yields in 12 h. The catalyst 3 is recyclable in the aminolytic kinetic resolution process and worked well up to six cycles with retention of enantioselectivity.     

Oil absorbents based on styrene–butadiene rubber

Four oil absorbents based on styrene–butadiene (SBR)—pure SBR (PS), 4‐tert‐butylstyrene–SBR (PBS), EPDM–SBR network (PES), and 4‐tert‐butylstyrene‐EPDM‐SBR (PBES)—were produced from crosslinking polymerization of uncured styrene–butadiene rubber (SBR), 4‐tert‐butylstyrene (tBS), and ethylene–propylene–diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a prepolymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with ASTM method F726‐81. The order of maximum oil absorbency was PBES > PBS > PES > PS. The maximum values of oil absorbency of PBES and PBS were 74.0 and 69.5 g/g, respectively. Gel fractions and swelling kinetic constants, however, had opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49.97 × 10^?2 h^?1. The gel strength parameter, S, the relaxation exponent, n, and the fractal dimension, d_f, of the crosslinked polymer at the pseudo‐critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. The morphologies and light resistance properties of the crosslinked polymers were observed, respectively, with a scanning electron microscope (SEM) and a color difference meter.     

Antioxidant mechanism of a 3‐arylbenzofuranone containing a 2′‐hydroxyl group

5‐Methyl‐7‐tert‐butyl‐3‐(2′hydroxyl‐5′‐methylphenyl)3H‐benzofuran‐2‐one (PCRBF2), is a better scavenger of 2,2‐diphenyl‐1‐picrylhydrazyl radicals than benzofuranone analogs without the 2′‐substituent, which indicates that PCRBF2 will cause good stabilization in polymers. To prove this further, antioxidation by PCRBF2 and other benzofuranone analogs, namely, 5‐methyl‐7‐tert‐butyl‐3‐(3′,4′‐dimethylphenyl)3H‐benzofuran‐2‐one (OXBF2) and 5‐methyl‐7‐tert‐butyl‐3‐(2′,5′‐dimethylphenyl)3H‐benzofuran‐2‐one (PXBF2), was comparatively studied in polypropylene. The resulting antioxidant activity order of these benzofuranones was PCRBF2 > OXBF2 > PXBF2, an observation showing that the hydroxyl group in the 2′‐position does not weaken the antioxidant activity of benzofuranone, but, on the contrary, increases it. Analyses by FTIR revealed intramolecular hydrogen bonding between the 3‐position hydrogen and the oxygen of the 2′‐hydroxyl group, which makes the 2′‐hydroxyl hydrogen of PCRBF2 more reactive than the 3‐position reactive hydrogen. Thus the hydroxyl group reacts with radicals first. J. VINYL ADDIT. TECHNOL., 19:198‐202, 2013. © 2013 Society of Plastics Engineers     

Synthesis of an acrylate elastomer with UV stabilization and its application in polyoxymethylene

In this study, an acrylate elastomer with light‐stable functional groups was synthesized by methyl methacrylate (MMA), butyl acrylate (BA), and a polymerizable UV stabilizer 2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone (BPMA) via emulsion polymerization, and the product was poly[methyl methacrylate‐co‐butyl acrylate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone] [poly(MMA‐co‐BA‐co‐BPMA)]. The composition and characteristics of poly (MMA‐co‐BA‐co‐BPMA) were determined by using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H‐NMR), and ultraviolet–visible absorption spectroscopy (UV–vis). Further, the obtained poly(MMA‐co‐BA‐co‐BPMA) was blended with polyoxymethylene (POM) to modify its photostabilization, as well as the mechanical properties of POM composite were tested before and after UV irradiation. The result showed that poly(MMA‐co‐BA‐co‐BPMA) can be dispersed well in the POM matrix, which could play a role of improving compatibility with and toughening for POM, and its light‐stable functional groups could increase the UV resistance of POM composite. Mechanical properties of modified POM were kept well with higher impact strength and elongation at break than pure POM after UV irradiation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene}

The reaction of methylhydroquinone with hexachlorocyclotriphosphazene in the presence of a base, 4‐picoline, in cyclohexane was investigated. Nuclear magnetic resonance spectroscopy, multiangle laser light scattering, and elemental analyses were performed on the product and two other related phosphazene materials produced by analogous synthetic routes: poly[hexakis(4‐hydroxyphenoxy)cyclotriphosphazene] (1) and hexakis[(3‐tert‐butyl)(4‐hydroxyphenoxy)]cyclotriphosphazene (2) . Unlike the data for 2 where the tert‐butyl moiety enforced regiospecific nucleophilic addition, the data for the methylhydroquinone‐substituted cyclotriphosphazene product indicate that the less sterically bulky methyl group provides only limited protection for the adjacent hydroxyl group. The result is the formation of a low molecular weight oligomer, poly{hexakis[(methyl)(4‐hydroxyphenoxy)]cyclotriphosphazene} (3) , instead of a discrete cyclic trimer species. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3439–3446, 2001