Effect of Resin Types and Antioxidants on Release of Off-Flavor From HDPE Bottles

The effects of three types of high-density polyethylene (HDPE) resins (A, B, and C) and three antioxidants (vitamin E, Irganox 1010, and BHT) on the release of off-flavor (including off-odor and off-taste) from blow-molded HDPE bottles were investigated using sensory analysis and gas chromatography/mass spectrometry (GC/MS) analysis. Overall the sensory study showed that off- flavor intensity was affected by both resin type and antioxidant. Resin A bottles yielded less off-flavor compared to resin B or C bottles. Vitamin E containing bottles yielded less off-flavor compared to Irganox 1010 or BHT containing bottles for resins A and B; however, the antioxidants have almost the same effect on resin C. The GC/MS study identified more than 60 volatile compounds released from the bottles, ranging from C₅ to C₂₀, which belonged to the groups of n-alkane, 1-alkene, aldehyde, ketone, phenolic, olefin, and paraffin—among them aldehydes and ketones were the most important due to their very low odor thresholds. Resin A bottles yielded less aldehyde and ketone compared to resin B or C bottles. Vitamin E containing bottles yielded less aldehydes and ketones compared to bottles containing Irganox 1010 or BHT. There was a general consistency between the sensory and GC/MS data. The aldehyde and ketone concentration was linearly correlated reasonably well to odor (R ² = 0.78) and taste scores (R ² = 0.67). Another study was also conducted, which shows vitamin E has smaller reduction in melt flow index due to blow molding compared to Irganox 1010 or BHT.     

Thermo-Oxidation of Polyethylene Stabilized with Irganox 1010 and Tinuvin 622

Abstract

Thermal oxidation of polyethylene stabilized with the mixture of Irganox 1010 and sterically hindered amine Tinuvin 622 confirmed that the occurrence of synergism or antagonism in the effect of sterically hindered amines towards antioxidants is concentration dependent. Provided that the concentration of phenolic antioxidant Irganox 1010 in polytheylene exceeds that of Tinuvin 622, synergism is observed at 185 and 190°C. Chemiluminescence, oxygen absorption method, nonisothermal differential scanning calorimetry (DSC) and differential thermal analysis (DTA) were used for testing of stabilizing efficiency of mixtures of stabilizers and the mutual correspondence of the results have been pointed out.     

Structural effect of secondary antioxidants on mechanical properties and stabilization efficiency of polyamide 6/halloysite nanotube composites during heat ageing

Hindered phenol (Irganox 1010) was combined with two kinds of secondary antioxidants [i.e., tris(2,4‐di‐tert‐butylphenyl) phosphite (Irgafos168) and tris(nonylphenyl) phosphite (TNPP)] to form antioxidant mixtures, and their influences on mechanical properties and thermo‐oxidative degradation of polyamide 6 (PA6) and halloysite nanotube (HNT) filled composites were investigated. The results showed that the antioxidant combinations provided an improvement in the oxidative induction time, decomposition temperature (T_d), processability, and tensile properties of PA6. Irganox/TNPP (1:1) was found to exhibit the best thermal oxidative resistance. The study of heat ageing in the air oven at 130 °C showed that the stabilized composites with 5 wt % of HNT could retain 92% of strength without loss of modulus. The physical characteristics of antioxidants such as low volatility and possible interaction with filler in the composites played a crucial role in stabilizing efficiency during heat ageing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45360.     

Mechanisms of antioxidant action: Photoantioxidant activity of polymer-bound hindered amines. II. Bis acrylates

1-Acryloyl-4-acryloyloxy-2,2,6,6-tetramethylpiperidine (AATP) has been covalently attached to polypropylene under conditions of reactive processing to give substantial concentrations of essentially 100% grafted antioxidant (AATP-B). Solution of the concentrates showed that at high concentration of grafted antioxidant some homopolymerized AATP was present and the polymer undergoes transient cross-linking during processing. Concentrates of bound AATP (AATB-B) when used as conventional additives for polypropylene are very effective photoantioxidants due to conversion to the related polymer-bound nitroxyl radicals by photosensitized oxidation. A typical commercial hindered phenol, Irganox 1076, when used at low concentration in combination with -B also acts as a photosensitizer for nitroxyl formation. Unlike low molar mass-hindered piperidinoxyl, polymer-bound nitroxyls are effective thermal antioxidants that synergize very effectively with low concentrations of Irganox 1076.     

复配型受阻酚类抗氧剂对聚甲醛的稳定作用

将受阻酚类抗氧剂Irganox245和Irganox1010进行复配并加入聚甲醛中，通过将物料在设定温度下多次挤出，测定挤出物料的黄色指数、拉伸强度、冲击强度、熔体质量流动速率、热失重率等方法对单剂和复配抗氧剂在聚甲醛中的稳定作用进行了研究。结果表明：将抗氧剂Irganox245和Irganox1010复配后，提高了聚甲醛的分解温度，较好地保持了聚甲醛的各项性能，没有发生劣化现象，作用效果介于两种抗氧剂单独作用效果之间；在聚甲醛的热氧稳定性能方面起到一定的协同作用。     

Investigating the impact of Cloisite® 15A nanoclays on the diffusivity of Irganox 1035 antioxidant in high-density polyethylene nanocomposite

Knowing the diffusion coefficients of antioxidants in packaging materials is essential to assess their effectiveness in protecting materials against oxidation, but also to prevent their eventual migration to food. In this work, the diffusion of a commercial phenolic antioxidant (Irganox 1035) was measured experimentally in pristine high-density polyethylene (HDPE) and in HDPE nanocomposite filled with 3 wt% of nanoclays (Cloisite® 15A). Diffusion experiments were performed using the Roe's method between 60 and 100°C. The local concentration of Irganox1035 in each film was measured by UV–Vis spectroscopy from the UV absorbance at 282 nm. The adjustment of the experimental data by Fick's second law allowed us to deduce the values of the diffusion coefficient of Irganox1035 at each temperature and to show that the temperature dependence of this coefficient obeys an Arrhenius' law. It is shown that the incorporation of 3 wt% of Cloisite®15A into HDPE significantly hinders the diffusion of Irganox 1035 and increases its activation energy. Several mechanistic assumptions could explain this result, first the increase in the tortuosity of diffusion paths, but also the possible establishment of strong intermolecular interactions between the antioxidant and some chemical groups on the nanofiller surface, or even the formation of an interphase with reduced molecular mobility around the nanofillers.     

3-芳基苯并呋喃酮在BOPP稳定过程中的作用

3-芳基苯并呋喃酮是一种高效自由基捕捉剂,它能有效地捕获以碳为中心的自由基,许多实验表明它在双向拉伸聚丙烯（BOPP）稳定过程中起到了重要作用。比较了3-芳基苯并呋喃酮与传统抗氧剂的抗氧机理,并将其与受阻酚类和亚磷酸酯类抗氧剂复配成三元抗氧剂DP101,通过其在BOPP中的测试实验,结果表明DP101的抗氧化性能优于传统的二元抗氧剂Irganox B225。     

Photoprotective agents for wool. Synergism between UV absorbers and antioxidants

Several antioxidants alone, and in combination with sulfonated UV absorbers, have been evaluated as photoprotective agents for wool. Mixtures of phenolic antioxidants and sulfonated UV absorbers of the 2-hydroxyphenylbenzotriazole class were found to exhibit synergistic behavior; the most effective UV absorber also gave the strongest synergistic effect with the antioxidants. Of the systems studied, the hindered phenol, calcium bis ((ethyl-(3,5-di-t-butyl-4-hydroxybenzyl)-phosphonate)) (Irganox 1425), when used in conjunction with a sterically hindered benzotriazolesulphonate, afforded wool the best protection against photoyellowing and phototendering in sunlight, behind window glass. Sulfonated derivatives of hindered phenols acted synergistically with UV absorbers when treated fabrics were exposed to an artificial light source, but not when fabrics were exposed to sunlight through glass.     

Influence of binary combined systems of antioxidants on the stabilization of peroxide‐cured low‐density polyethylene

The secondary antioxidants Irganox 168 and 242 and dilaurylthiodipropionate (didodecyl‐3,3′‐thiodipropionate) (DLTP) were chosen to be combined with the primary phenol antioxidants Irganox 300, 1010, 1035, and 1076, and the effects of the binary combined systems of antioxidants on the peroxide curing reaction and the long‐term stability of crosslinked low‐density polyethylene (XLPE) were studied through isothermal dynamic rheological and mechanical testing. The results show that the primary phenol antioxidants with lower melting points had better resistance to scorching and exhibited good synergistic effects with the secondary antioxidants. Irganox 168 had little resistance to scorching, whereas Irganox DLTP had moderate resistance, and Irganox 242 had the greatest resistance. Irganox 168 and DLTP guaranteed the mechanical properties well, whereas Irganox 242 reduced the tensile strength obviously. Irganox 300 and 1035 combined with secondary antioxidants performed poorly in long‐term thermal aging test, whereas Irganox 1076 in combination with secondary antioxidants displayed a moderate effect of aging resistance, and Irganox 1010 showed the best effect. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Effects of two antioxidants with different degrees of steric hindrance on the thermal-oxidative aging properties of ABS resin

ABS resin is easily oxidized and deteriorated during use or processing. The addition of antioxidants is an effective method for improving ABS oxidation. The hindered phenol antioxidant DBHMIE and the asymmetrically hindered 245 were added separately or together to ABS; the oxidation induction temperature of ABS increased by 10.6, 12.1 and 14°C, with the addition of DBHMIE, 245 and their combination, respectively, and the initial decomposition temperature T3% increased by 29.7, 16.2 and 51.3°C, respectively. The addition of these two antioxidants to ABS did not greatly affect the mechanical properties of the material, but the impact strength increased by 2.24 kJ/m² when both antioxidants were added together. During the thermal aging test, the decomposition temperature of the ABS splines prepared with the combined antioxidants increased during the first few cycles. The impact strength of the splines prepared with the combined antioxidants was the highest, with the smallest decrease of only 5.18%. The yellow index of the spline prepared with the combined antioxidants was between those of splines prepared with the antioxidants added alone. The combination of DBHMIE and 245 induced synergistic effects, improved thermal-oxidative aging resistance, and improved and protected the toughness of ABS resin.     

Synthesis,characterization, and application of a hydrolytically stable liquid phosphite

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by negatively affecting the kinetics. In particular, liquid phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers, but they are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in liquid phosphites, a novel hydrolytically stable liquid phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:163–168, 2016. © 2014 Society of Plastics Engineers     

Synthesis,characterization, and application of oligomer‐type‐based phosphites

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by affecting the kinetics. In particular, oligomer‐type phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers. Generally, phosphites are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in phosphites, a novel hydrolytically stable oligomeric phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:146–155, 2016. © 2014 Society of Plastics Engineers     

Alkylated phenolic resins as antioxidants for rubber

Polymeric antioxidants based on p‐nonyl phenol formaldehyde resin (PNPF) and p‐dodecyl phenol formaldehyde resin (PDPF) were prepared by the condensation reaction of the respective phenols with formaldehyde in the presence of an acid catalyst. The reactions were monitored by thin layer chromatography, and the melting points of the products were determined. These compounds were incorporated in natural rubber mixes to evaluate their antioxidant properties. The compounded mixes were characterized for their rheometric properties. The compression‐molded rubber sheets were tested for their mechanical properties. The effects of aging on the mechanical properties of these molded sheets were evaluated. Both PNPF and PDPF showed better antioxidant properties than the conventional styreneated phenol antioxidant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2649–2651, 2006     

A molecular model for solid-state polymerization of nylon 6

Transport properties of antioxidants in polymers have a very important role in their effectiveness. Lifetime of a product is strongly influenced by the physical loss of the stabilizer. The diffusion coefficient (D) and solubility (S) of Irganox 1010 in low-density polyethylene (LDPE) were studied at 45 and 80°C, changing the physical state of the antioxidant in the additive source. Irganox 1010 is a polymorphous material; its actual morphology depends on the thermal history. It was proved that the morphology of the additive has a determining effect on the measured D and S values. Contradictions in the literature data can be explained by the differences in the experimental conditions, i.e., in the physical state of the penetrant in the additive source and the crystallinity and orientation of the polymer.     

抗氧剂在聚氯乙烯加工中的应用

重点研究了抗氧剂对高钛白颜料含量和含金属颜料的PVC压延膜制品加工过程的作用机理及效果,指出对于高钛白含量的PVC压延膜制品,使用受阻酚类抗氧剂是有效且可取的;对于含有金属颜料的PVC压延膜制品,加入金属钝化剂和受阻酚类抗氧剂能有效阻止其在加工过程中的热降解及氧化降解。     

Performance and synergistic effect of phenolic and thio antioxidants in ABS graft copolymers

The synergistic effect of phenolic and thio antioxidants on the stabilization of acrylonitrile-butadiene-styrene (ABS) graft copolymers has been studied. Three commercial antioxidants Irganox245, Irganox1076 and dilauryl thiodipropionate (DLTP) were selected. Formulations based on hindered phenols and secondary antioxidant DLTP were prepared. Stabilization was monitored in terms of changes in the functional groups (oxidation products), tensile properties and yellowness index. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were also used to assess the stability. The results indicated that the combination of Irganox245 and DLTP showed much better stabilization effect than the individual components due to the strong synergistic effect. Only weak synergism could be observed in the formulation that contained Irganox1076 and DLTP. Irganox1076 and Irgnox1076/DLTP exhibited similar behaviors between antioxidants with the highest and lowest efficiencies.     

CURING OF PARA-TERT-BUTYLPHENOL FORMALDEHYDE EPOXY-ACRYLIC RESIN IN THE PRESENCE OF REACTIVE DILUENTS

Para-tert-butylphenol formaldehyde epoxy-acrylic resin was synthesized starting from para-tert-butylphenol formaldehyde resin in reaction with glycidyl acrylate. It was cured as such, or in the presence of reactive diluents based on glycidyl ethers of phenol, para-tert-butylphenol, as well as para-nonylphenol, respectively. The curing reaction was studied by the viscometry technique at temperatures in the range 60–90°C. The curing starts with gelation and with resin measurable rates only in the case of the resin diluted with both para-tert-butylphenol and para-nonylphenol epoxy-acrylic diluents. The analyzed samples heated on 110°C, duration 16 h, show that the curing reaction depends very much on the structure of the reactive diluents.     

Enzymatic Synthesis of Tyrosol-Based Phenolipids: Characterization and Effect of Alkyl Chain Unsaturation on the Antioxidant Activities in Bulk Oil and Oil-in-Water Emulsion

Oxidative stability of lipids is one of the most important parameters affecting their quality. Lipase‐catalyzed lipophilic tyrosyl esters with an equivalent carbon alkyl chain but different degrees of unsaturation (C18:0 to C18:4n3) were prepared, characterized, and used as antioxidants. Free fatty acids and fatty acid ethyl esters (substrate molar ratio tyrosol: acyl donor, 1:10) were used as acyl donors and immobilized lipase from Candida antarctica was the biocatalyst (10 %). The phenolipids were isolated and characterized using ESI–MS, ¹H‐NMR, and ¹³C‐NMR. Peroxide value (PV) and para‐anisidine value (p‐AV) were measured to evaluate their antioxidant activities in bulk oil structured lipid (SL) and in an oil‐in‐water emulsion (SL‐based infant formula). No significant difference was found in yield and reaction time between the two types of acyl donors. However, as the unsaturation of the fatty acids increased the reaction time also increased. In SL, tyrosyl esters exhibited lower antioxidant activity than tyrosol whereas the addition of an alkyl chain enhanced the antioxidant efficiency of tyrosol in infant formula. Tyrosyl oleate was the most efficient antioxidant in the emulsion system followed by tyrosyl stearate and tyrosyl linoleate. These results suggest that the synthesized phenolipids may be used as potential antioxidants in lipid‐based products.     

The influence of stabilizers on mechanochemical processes in SBR rubbers

Mechanochemical processes in commercial and model SBR rubbers containing different stabilizers were investigated. The influence of chemical structure and concentration of stabilizers in the temperature range from 20–170°C and in the presence of air, i.e., under conditions similar to that in industrial processes, were studied. Stabilizers used were diaryl‐p‐phenylene‐diamine, alkyl‐aryl‐p‐phenylene diamine, polynuclear phenol, aryl‐alkyl phenol, and alkyl‐alkyl phenol. It was found that mechanochemical processes in SBR rubbers are less developed in the temperature region from 70–130°C, so the influence of stabilizer is less expressive. During increasing temperature (130–170°C) structure and concentration of stabilizers both show a strong influence on type and intensity of mechanochemical processes in SBR rubbers: p‐phenylene‐diamines favor processes of linear degradation, while phenol stabilizers direct them toward branching and crosslinking, which is more expressed in the presence of aryl‐substituted phenols than alkyl‐substituted phenols. This fact is based on the differences in stability of free stable radicals of p‐phenylene‐diamines, alkyl‐substituted phenols and aryl‐substituted phenols. The fact that phenol stabilizers are involved in chain degradation as well as in branching and crosslinking processes during rubber processing, can be of high practical importance. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 835–847, 1999     

Photostabilization of styrene–ethylene–butylene–styrene block copolymer by hindered phenol and phosphite antioxidants

The photostabilization of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS), by hindered phenols and their combination with phosphite antioxidants has been studied by using a variety of spectroscopic methods including FTIR, UV, and luminescence spectroscopy coupled with crosslinking and hydroperoxide analysis. The addition of a hindered phenol was found to photostabilize the SEBS in terms of the inhibition of discoloration, and the formation of hydroperoxides, acetophenone, and oxidation products, as well as chain scission and disaggregation of the styrene units. Strong synergism was found with combinations of a hindered phenol and phosphite antioxidant, especially with an increase in the phosphite concentration. Residual titanium traces present as impurities in the material were found to play an important role in the photo‐oxidation of SEBS. Molecular weight appeared to be a determining factor in the proportion of chain scission/crosslinking reactions that occured. Nevertheless, the addition of antioxidants and the reduction of titanium content also proved satisfactory in stabilizing the low‐molecular‐weight material. J. VINYL. ADDIT. TECHNOL. 12:2–7, 2006. © 2006 Society of Plastics Engineers