Loss and transformation products of the aromatic antioxidants in MDPE film under long‐term exposure to biotic and abiotic conditions

The loss of a primary phenolic antioxidant Irganox 1010 and of a secondary phosphite antioxidant Irgafos 168 from a medium density polyethylene film (MDPE) was investigated after exposure of the film for 4 years to different environments such as aqueous media at pH5 and 7, open air, and compost, with an exposure of exposition of 25°C. An ultrasonic extraction technique using chloroform as extraction solvent was applied to recover the residual antioxidants from the polymeric matrix, and this was followed by High‐Performance Liquid Chromatography (HPLC) with acetonitrile as mobile phase and a quantitative analysis at a wavelength of 280 nm of the extracted antioxidants. The amount of antioxidant lost varied remarkably depending on the testing medium. The fastest loss of antioxidant was found on exposure to open air and sunlight while the slowest loss was observed in compost. Thermo‐analytical measurements were made to characterize the residual thermo‐oxidative stability of MDPE film in terms of oxidation temperature and oxidation induction time, to provide a greater insight into the underlying mechanisms of ageing in the different environments. Analysis by Gas chromatography–Mass Spectrometry (GC‐MS) revealed that degradation of the polymeric matrix resulted in the formation of hydrocarbons and oxygen‐containing compounds such as alcohols, carboxylic acids, aldehydes, and esters. The transformation products of the antioxidants formed as result of processing or exposure to the tested media were also identified. The transformation of the phenoxy radical of the Irganox 1010 produced the ester, acid, dealkylated cinnamate, and quinone products, whereas Irgafos 168 yielded oxidation products and the phenolic hydrolysis byproduct 2,4‐di‐tert‐butylphenol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 974–988, 2002     

Antioxidation and mechanism of phosphites including the free phenolic hydroxyl group in polypropylene

Inhibiting the degradation of polypropylene (PP) in melt processing and usage is an important issue in the plastic industry. It is becoming more and more urgent to increase the antioxidation of phosphites alone while maintaining the water resistance. In this study, one phosphite antioxidant, named bis‐2,2′‐methyl‐4,6‐di‐tert‐butylphenyl phosphite (BM46TBPP), which contains a water‐resistant inner ring and a free phenolic hydroxyl group together, was synthesized. Then, antioxidation in PP was characterized with multiple extrusions and oxidation induction times (OITs). Finally, the hydrogen‐donating ability of this antioxidant was tested with 2,2‐diphenyl‐1‐picrylhydrazyl radical colorimetry to explain the antioxidation mechanism. The results show that the phosphite BM46TBPP displays better antioxidation than tris(2,4‐di‐tert‐butylphenyl) phosphite (Irgafos 168) in melt processing and OIT testing. Furthermore, the priority of this antioxidant was more obvious when it was used in the presence of oxygen, so the antioxidant even made the PP stabilized by it alone show a longer OIT value than the PP stabilized by the complex system including Irgafos 168 and 2,4‐di‐tert‐butylphenol because there was a free phenolic hydroxyl group in the BM46TBPP antioxidant molecule and the hydroxyl group made the antioxidant show intermolecular synergistic antioxidation through hydrogen donation to radicals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44696.     

Effect of different additives and their mixtures on thermal stability of polyethylene synthesized using iron and titanocene hybrid catalysts

Traditionally, additives are introduced into a polymer matrix via extrusion process which consumes a high amount of energy. In this study, the use of different additives including antioxidants for the in‐reactor stabilization of polyethylene has been investigated in order to provide an energy saving system. Particular attention was dedicated to the efficiency of antioxidant influencing the catalysts activity and properties of polymers. The effect of the addition of Irganox 1330 and Irgafos 168 antioxidants and zinc stearate on the activities of metallocene, post‐metallocene, and their supported hybrid were studied. In addition, the effect of different additives on the thermal characteristics of the synthesized polymers and oxidative induction time (OIT) was evaluated. Our polymerization results exhibited that the factors such as chemical structure of antioxidant and its steric hindrance, type of catalysts, and their hybrid could affect the catalyst performance and OIT contents. The use of antioxidants mixture and hybrid of catalysts is a way that can increase oxidation resistance of polymers considerably. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45482.     

Improvement of ageing properties of rubber films prepared from radiation-vulcanized natural rubber latex

Radiation-vulcanization of natural rubber latex (NRL) with n-butyl acrylate gives a higher tensile strength for films obtained after casting. The ageing properties of radiation-vulcanized natural rubber in the presence of various antioxidants have been investigated. In order to find out suitable antioxidants for radiation-vulcanized natural rubber latex (RVNRL) films, extraction of the gel fraction was carried out in xylene with 1 wt.-% antioxidant and air bubbling. Antioxidants which give less reduction in gel fraction due to oxidative degradation during extraction are effective for ageing tests of RVNRL films. It was found that tris(nonylated phenyl) phosphite (Nonflex TNP) and 2,5-di-tert-amylhydroquinone (Antage DAH), among 12 different antioxidants tested, were the most effective antioxidants for RVNRL films.     

Influence of shape and surface modification of nanoparticle on the rheological and dynamic‐mechanical properties of polyamide 6 nanocomposites

Nanocomposites of polyamide 6 (PA6) with different concentrations of silane‐treated, organic‐treated, and nontreated nanoparticles of halloysite (HNT) and montmorillonite (MMT) had their microstructure and melt and solid state rheological behavior analyzed. The microstructure analysis was done using transmission electron microscopy (TEM) and wide angle X‐ray diffraction (WAXD); the effectiveness of the silanization was studied by thermogravimetric analysis (TGA) and Fourier transform infrared. It was found that exfoliation occurred in the organic‐treated MMT, but not in the silane‐treated MMT and that silanization was small in the HNT nanoparticles (due to its low amount of surface hydroxyls groups). Steady state shear, small amplitude oscillatory, and transient tests also indicated that: (i) only the nanocomposites with organic‐treated MMT, at concentrations above the theoretical percolation threshold developed a percolated network; (ii) the silane treatment increased the shear elastic modulus (G) of the PA6/HNT nanocomposites in the solid state, but not of the PA6/MMT; (iii) the organic‐treated MMT formed composites with the highest G, as expected. Thus, it was concluded that the HNT nanoparticles had a high potential as nanofiller for PA6, but further research on more efficient compatibilizers for HNT is still needed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

Synthesis and performance of phenolic polybutadiene‐bound stabilizers

An antioxidant derivative, 6‐sulfanylhexyl 3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propanoate, was synthesized and examined. With a radical initiator, the addition of this compound to pending vinyls of OH‐telechelic, low molecular weight liquid polybutadiene (LBH) was performed to various degrees of conversion to form polymeric antioxidants (PAOs) in which the phenolic moiety was separated from the main chain by a spacer [? CH₂CH₂? S? (CH₂)₆? O? CO? ]. Pure, unstabilized LBH was mixed in several ratios with PAOs, Irganox 1520, and Irganox 1076, and the oxidation stabilities of these mixtures, determined by thermogravimetric analysis and differential scanning calorimetry, were compared. Probably because of their good compatibility with LBH, PAOs exhibited equal or better effectiveness than commercial antioxidants of the Irganox type. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 885–889, 2003     

Preparation of viscoelastic gel‐like halloysite hybrids and their application in halloysite/polystyrene composites

Self‐reinforcement gel‐like halloysite nanotube (g ‐HNT ) hybrids with various viscoelastic behaviors were fabricated by firstly treating with various concentrations of sodium hydroxide (NaOH ) solution and then grafting tertiary amine and ion‐exchange reacting with sulfonate anions. The morphology, composition, thermal stability and rheological behavior of the g ‐HNT hybrids were systematically characterized and analyzed using various methods. It is found that the viscoelasticity of g ‐HNT hybrids can be easily regulated by using different NaOH solution‐treated HNTs as inorganic core and temperatures. In addition, the g ‐HNT hybrids treated with medium concentration of NaOH (0.06 mol L^?1) have the lowest viscosity and highest level of dispersion compared with those treated with other concentrations of NaOH solution. Due to the amphiphilic nature of g ‐HNT hybrids and their lower viscosity than HNT powder, as novel hybrid fillers, they were utilized to prepare polystyrene composites by direct melt blending for achieving simultaneous reinforcement and plasticization effects. Besides the above mentioned advantages, the thermal conductivity of polystyrene composites is also surprisingly improved by reducing the interfacial mismatch between the filler and polymer matrix. The solvent‐free and self‐reinforcement hybrids provide a convenient and green path for fabricating high‐performance polymer composites. © 2017 Society of Chemical Industry     

Influence of the chemical structure of para-bridged group on the antioxidant behavior of hindered phenol antioxidants in HDPE resin

A hindered phenol antioxidant with rigid para-bridged group (antioxidant AP) was synthesized to study the effect of the chemical structure on the antioxidant properties of hindered phenol antioxidants in high density polyethylene (HDPE). Antioxidant behavior of series of hindered phenol antioxidants with different para-bridged groups in HDPE resin was also investigated by the thermal oxidation experiment, the mobility test, and the long-term accelerated thermal aging test. The results showed that the rigidity of para-bridged group and the molecule size have the important influences on the antioxidant performance of hindered phenol antioxidants in the HDPE resin, and the antioxidant abilities of antioxidant AP and Irganox 1,330 with the aryl para-bridged group was superior to Irganox 1,098 and 1.0G dendritic antioxidant with the alkyl para-bridged group at the same testing conditions. Compared with the hindered phenol antioxidants with alkyl para-bridged group, the hindered phenol antioxidants with aryl para-bridged group have better thermal oxygen stability and less mobility in the HDPE resin. Irganox 1,010 with ester groups is prone to hydrolysis to increase the mobility rate in hot water and the migration resistance of hindered phenol antioxidants in n-hexane. Moreover, the high content of phenolic OH group and the aryl para-bridged group are favorable for improving the antioxidant performance of hindered phenol antioxidants.     

Effects of thermal ageing treatment and antioxidants on the positive temperature coefficient characteristics of carbon black/polyethylene conductive composites

Polyethylene (PE)‐filled with carbon black (CB) is a prototypical composite that displays resistance switching. These materials can exhibit either a positive temperature coefficient (PTC) or negative temperature coefficient (NTC). The CB‐filled semicrystalline polymer composites ideally need antioxidants, which stabilize the composites against thermooxidative degradation, because they should be resistant to the severe conditions of high temperature. The characterization of PTC materials is affected by the crystallinity of the polymer, and the crystallinity of the polymer is changed with thermal ageing treatment. Thermal ageing of PTC samples was conducted in an oven in the range 50–140°C, in air. The composites, containing 0.5–3% (by weight) Irganox 1076 (Ciba‐Geigy), were irradiated under nitrogen at room temperature with different doses of gamma rays from a ⁶⁰Co source. The resulting composites were analyzed by differential scanning calorimetry, gel fractionation, X‐ray diffraction, and dynamic mechanical analysis. The conductivity of the composites depended on the amounts of antioxidants and the duration of the thermal ageing treatment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2316–2322, 2003     

复合型防老剂对树脂级低顺式聚丁二烯橡胶性能的影响

研究9种防老剂单用和并用对树脂级低顺式聚丁二烯橡胶(LCBR)性能的影响。结果表明:在9种防老剂中,单独使用防老剂1010、防老剂1520和西尼尔6308的防老化效果较好;复合使用防老剂时,防老剂1010/TNPP和防老剂1520/TNPP并用体系的防老化效果较好;当防老剂1010/TNPP并用比为80/20或防老剂1520/TNPP并用比为70/30时,LCBR的耐热氧老化性能最佳;防老剂1010/TNPP和防老剂1520/TNPP并用体系均能提高改性树脂HIPS和ABS的物理性能。     

Photodegradation and stabilization of styrene–butadiene–styrene rubber

Photooxidative degradation and stabilization of a polystyrene–block–polybutadiene–block–polystyrene thermoplastic elastomer using a polychromatic UV light in air at 60°C has been studied by monitoring the appearance of the hydroxyl and carbonyl groups in Fourier transform infrared spectroscopy. The extent of photooxidative degradation in different samples has been compared. The rate of photooxidation was also estimated in the presence of different concentrations of 2,6‐di‐tert‐butyl‐4‐methylphenol [BHT], 2‐(2′‐hydroxy‐5′‐methylphenyl)benzotriazole [Tinuvin P] and tris(nonylphenyl) phosphite [Irgafos TNPP], and 1,2,2,6,6‐pentamethyl piperidinyl‐4‐acrylate was grafted onto the surface of the SBS film. The kinetic evolution of the oxidative reaction was determined. The morphological changes upon irradiation in the solution cast SBS films were studied by scanning electron microscopy. Based on the experimental data a suitable photooxidative degradation mechanism also has been proposed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1097–1102, 2000     

Evaluation of the oxidative stability of multiextruded polypropylene as assessed by physicomechanical testing and simultaneous differential scanning calorimetry–chemiluminescence

Common physicomechanical tests comprising impact strength, the melt flow index (MFI), and the yellowness index (YI) were used to study the thermooxidative stability of polypropylene (PP) following multipass extrusion. Differential scanning calorimetry (DSC) coupled with chemiluminescence (CL) monitoring was also used to assess the stability. Three PP formulations were studied: (i) PP‐1 containing 0.050% w/w of the phenolic antioxidant Irganox 1010^™, (ii) PP‐2 containing 0.028% w/w Irganox 1010, 0.056% w/w of the phosphite costabilizer Irgafos 168^™ and 0.014% w/w of the lactone processing stabilizer HP 136^™, and (iii) PP‐3 containing 0.050% w/w Irganox 1010 and 0.100% w/w of the phosphite Ultranox 641^™. All formulations contained 0.045% w/w of the hydrotalcite acid scavenger DHT‐4A^™. The results suggest that physicomechanical tests cannot reliably detect the small difference in the stability between PP‐2 and PP‐3 but can detect the larger difference between these and the less stable PP‐1. The oxidative induction time (OIT) determined by CL monitoring (i.e., CL– OIT) is consistent with the OIT determined by DSC but has better reliability. The CL–OIT data suggest that PP‐3 has superior oxidative stability to PP‐2 in the early stages of multipass extrusion. However, PP‐2 exhibits a better resistance to yellowing. A correlation between the CL–OIT data and each of the MFI and YI data was found. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 733–741, 2001     

Comparative evaluation of the efficiency of a series of commercial antioxidants studied by kinetic modeling in a liquid phase and during the melt processing of different polyethylenes

An antioxidant response in condensed polymeric environments is often ambiguous and may vary strongly depending on the nature of the polymer and the conditions of polymer storage, processing, and use. The impact of polymeric environments during melt processing on the intrinsic efficiency of a set of commercial antioxidants was studied. The antioxidative activity of primary antioxidants Lowinox CPL, Lowinox 22IB46, Naugard 445, hydroxylamine Genox EP, and secondary phosphite Weston TNPP were determined by using two versions of the model reaction of cumene initiated (2,2′‐azobisisobutyronitrile, AIBN, and cumyl hydroperoxide, ROOH) oxidation. The melt stabilizing efficiency of the antioxidants was also studied during multipass extrusion testing in HDPE (Phillipstype), metallocene LLDPE, and (Ziegler‐Natta) LLDPE. The kinetic measurements showed that each of the three functional hydroxyl groups of Lowinox CPL is consumed in the model reaction (version 1) with the same high inhibition rate constant (k₇), whereas the two functional groups of Lowinox 22IB46 have different activity stipulated by hydrogen bonding between the hydroxyls. All the primary stabilizers involved afforded transformation products with additional antioxidative activity. For phenolic Lowinox CPL and amine Naugard 445, these products exhibited lower inhibition rate constants than that of the main functionality, but for Lowinox 22IB46, the discrepancy was not observed. Genox EP revealed three inhibition centers with different rate constants which, however, have low values of the inhibition coefficients (f). This effect is presumably due to the versatility of the inhibition pathways for the antioxidant and its intermediates, including the path of active interception of cumylalkyl (R^?) radicals. The secondary stabilizer Weston TNPP, tested by means of the second version of the model system, along with the expected decomposition of hydroperoxide appeared to be an effective radical scavenger. Kinetic parameters of the antioxidizing activity of the stabilizers – inhibition rate constants, coefficients of the oxidation chain termination, and total antioxidative activity {A = ∑[k_7(i) (fn[InH])_(i)]} — were determined for each functional group and for the whole antioxidant molecule. The phenolic stabilizers manifested powerful antioxidative activity. Their strongest functional groups have very high inhibition rate constant values: (log k₇) = 5.4 ± 0.15 (Lowinox 22IB46) and 5.2 ± 0.1 M^?1s^?1 (Lowinox CPL). In terms of the total inhibiting activity in the liquid system the antioxidants can be ordered as: Lowinox CPL > Lowinox 22IB46 > Naugard 445 > Genox EP > Weston TNPP. The effect of stabilizers during multipass extrusion experiments was assessed via melt flow rate and yellowness index measurements conducted as a function of the number of passes. Phenolic antioxidants and Genox EP significantly improved the melt stability of the polyethylenes in terms of melt viscosity retention and in partial compliance with the data from kinetic modeling measurements. According to the melt stabilizing efficiency data, the antioxidants can be arranged as: Lowinox 22IB46 > Lowinox CPL > Genox EP > Naugard 445 > Weston TNPP. The Lowinox 22IB46 with relatively lower molecular weight exhibited the best results among the primary stabilizers because of the unrestricted molecular dynamics in the viscous‐flow state of the polymer. Yellowness index measurements made after multiple extruder passes indicated that Weston TNPP effectively decreased the color development caused by the phenolic antioxidants. Genox EP displayed high efficiency as an antioxidant and melt‐processing stabilizer and additionally provided good color protection. Generally, we received a good correlation between the activity of the antioxidants in the model system and their melt stabilization performance in HDPE, metallocene LLDPE, and LLDPE. The model reaction of cumene‐initiated oxidation has demonstrated excellent applicability as an effective tool for preliminary quantitative assessment of antioxidant radical‐scavenging efficiency. J. VINYL ADDIT. TECHNOL., 2010. © 2009 Society of Plastics Engineers     

Improvement of melt stability and degradation efficiency of poly (lactic acid) by using phosphite

Concurrent improvement of melt processing stability and degradation efficiency of poly(lactic acid) (PLA) is still a challenge for the industry. This article presents the use of phosphites: tris(nonylphenyl) phosphite (TNPP) and tris (2,4-di-tert-butylphenyl) phosphite (TDBP), to control the thermal stabilization, mechanical performance, and hydrolytic degradation ability of the compressed PLA films. The hydrolysis process is followed as a function of time at 45, 60, and 75°C. During melt extrusion, both phosphites function as a processing aid, besides acting as a chain extender stabilizing the PLA molecular weight. The phosphite structure plays a crucial role over crystallinity and water absorption, in controlling the hydrolytic degradation of PLA. The application of TNPP significantly catalyzes the hydrolysis of PLA, which is the initial step of the biodegradation process. The optimum amount of TNPP for best hydrolytic degradation efficiency and thermal stabilization of PLA is 0.5 wt%. The excessive TNPP loadings cause a drastic drop in PLA molecular weight and, as a consequence, a reduction of flexural strength. The reactions between PLA and phosphite molecules are discussed.     

尼龙6在热氧老化中的性能与结构变化

通过挤出共混法制备了添加不同抗老化助剂的尼龙6(PA6),以改善PA6的耐老化性能。考察了PA6试样暴露在125℃的热空气中一定时间后其黄色指数(YI)、色差(△E)、热稳定性能和力学性能的变化;系统地研究了不同抗氧剂对PA6在这一热氧老化过程中的变色行为和力学性能的影响;以黄色指数值达到55作为失效的指标,对PA6热氧老化试样进行了静态使用寿命的分析与预测;使用红外光谱(FTIR-ATR)分析了PA6试样在热氧老化过程的结构变化。研究结果表明:使用胺类抗氧剂能明显地改善PA6的抗热氧老化变色性能,还能使其保持较高的热稳定性能和力学性能,并大大延长PA6的静态使用寿命;用酚类抗氧剂/亚磷酸酯抗氧剂组成(1:1)的稳定体系能对改善PA6的耐热氧老化性能产生协同效应。     

Crystallization behavior and morphology of polylactide and PLA/clay nanocomposites in the presence of chain extenders

The effect of clay and chain extender on the nonisothermal, isothermal crystallization kinetics, and morphology of polylactide (PLA) was investigated in this study. PLA and PLA‐based nanocomposites containing 2 wt% organoclay were prepared via melt compounding. Three commercially available chain extenders were used: polycarbodiimide (PCDI), tris(nonylphenyl) phosphite (TNPP), and Joncryl ADR4368F. The nanoclay particles were found to act as nucleating agents. Chain extender incorporation, however, had diverse effects on both crystallization rate and degree of crystallinity. Nonisothermal DSC results revealed that the addition of PCDI increased the cold‐crystallization temperature (T_c) from 106 to 114°C, reduced the degree of crystallinity from 6.3 to 5.3%, and resulted in the formation of bimodal melting peaks in PLA. On the other hand, the reduction of chain ends in the presence of TNPP resulted in a significant increase of the crystallization rate and degree of crystallinity from 6.3 to 15.2%. In the case of Joncryl, its incorporation led to the formation of a long‐chain branching structure, which disrupted the chain packing. Therefore, the degree of crystallinity (from 6.3 to 1.6%) and the rate of crystallization decreased, while T_c was increased from 106 to 122°C in the presence of Joncryl. POLYM. ENG. SCI., 2013. © Society of Plastics Engineers     

Synergistic flame‐retardant effect of phosphaphenanthrene derivative and aluminum diethylphosphinate in glass fiber reinforced polyamide 66

The synergistic flame‐retardant (FR) effect of 1,1′‐bis(4‐hydroxyphenyl)‐metheylene‐bis(9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide‐2‐hydroxypropan‐1‐yl) (DPOH) and aluminum diethylphosphinate (AlPi) composites on glass fiber reinforced polyamide 66 (PA) was investigated by limiting oxygen index (LOI) tests, vertical burning (UL94) tests, and cone calorimeter tests. DPOH/AlPi system with 1:1 mass ratio increased UL94 ratings, suppressed heat release rate and increased residue yields of PA composites, and DPOH/AlPi system also imposed high LOI values and lower total heat release values to PA composites. All these results verified excellent synergistic FR effect between DPOH and AlPi. The reason of DPOH/AlPi system with higher flame‐retardant efficiency was caused by the quenching effect as good as that of DPOH and also by the higher charring effect than that of AlPi. DPOH/AlPi system possesses good flame retardancy in gas phase and also the strengthened FR effect in condensed phase compared with DPOH and AlPi alone, which led to excellent synergistic FR effect between the two components DPOH and AlPi. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45126.     

Effects of phenolic antioxidants on ultrahigh molecular weight polyethylene/decalin solution

The degradation of ultrahigh molecular weight polyethylene (UHMW‐PE) during its dissolution into decalin is discussed. The stabilization of the solution by three phenolic antioxidants, octadecyl β‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate (1076), tetrakis[methylene‐β‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate]methane (1010), and 1,1,3‐tris(2‐methyl‐4‐hydroxy‐5‐tert‐butylphenyl)butane (CA), and an auxiliary antioxidant, dilaurylthiodipropionate (DLTP) is also discussed. Among the three phenolic antioxidants, 1076 had the greatest effect. The auxiliary antioxidant was effective in stabilizing the solution when combined with one of the three phenolic antioxidants. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2877–2881, 2000     

Intercalated hydrotalcite‐like materials and their application as thermal stabilizers in poly(vinyl chloride)

The preparation of hydrotalcites with traditional materials is often based on the corresponding salts and alkali solutions. In this study, to facilitate industrial synthesis and take advantage of the lower cost during the process, a Ca–Al–HPO₃–layered double hydroxide (LDH) was directly synthesized with calcium hydroxide, aluminum hydroxide, and sodium phosphite powders. X‐ray diffraction, Fourier transform infrared, and scanning electron microscopy analyses confirmed the successful synthesis of the phosphite‐intercalated hydrotalcite. Compared with Ca–Al–CO₃–LDH, Ca–Al–HPO₃–LDH enhanced the heat stability of poly(vinyl chloride) (PVC) in terms of both short‐term and long‐term stability because phosphite replaced the allyl chloride and reacted with the conjugated double bonds in PVC; this was deduced through a thermal aging test. The composites of Ca–Al–HPO₃–LDH, zinc stearate, and calcium stearate had a synergetic effect when added to PVC and exhibited excellent thermal stability. In addition, the phosphite reacted with ZnCl₂ in case of the phenomenon of zinc burning. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44896.     

Loading the polyol carbonization agent into clay nanotubes for the preparation of environmentally stable UV‐cured epoxy materials

The halloysite nanotubes (HNTs) were loaded with pentaerythritol (PER). The as‐prepared composite (HNT‐P) and ammonium polyphosphate (APP) was subsequently added to the UV‐curable epoxy resins, giving a new flame‐resistant system. Loading of the hydrophilic PER into HNT can reduce the moisture absorption in the UV‐curable epoxy resins. The flame retardancy was evaluated by means of the cone calorimeter and limit oxygen index test. The results showed that the flame retardancy of the modified epoxy resin was greatly improved with an obvious decrease in both the heat release and smoke release. Moreover, it was revealed that HNT could catalyze the reaction of APP and PER, and the burning surface of the epoxy resin should be covered by the polyphosphoric‐HNT intumescent char layer. We have measured the moisture sorption and dynamic mechanical properties of the UV‐cured epoxy resins. As compared to the use of the simple mixture of PER and HNT, the use of the HNT‐P nearly kept the storage modulus at about 1809 Mpa and reduced the moisture absorption by 58.2 wt % at 40 °C. The results proved that the addition of the HNT‐P obtained lower moisture absorption and higher stability of the mechanical properties than adding the simple mixture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45045.