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We present data on the study of how the concentrations of powdered copper and crosslinking agents influence the properties of composites materials based on low-density polyethylene, compatibilizer, and copper. It was shown that the addition of copper favors an increase in the softening temperature of the composite materials. Two physical states, solid and viscous-flow ones, were detected depending on the test temperature. The optimum concentrations of curing agents, upon addition of which the crosslinked composites based on low-density polyethylene were characterized by three physical states, solid, viscoelastic, and viscous-flow ones, were shown. [ABSTRACT FROM AUTHOR]

Thermal runaway of chemical reactions often lead to secondary decomposition of the material, especially with autocatalytic decomposition characteristics. Autocatalytic decompositions are often characterized by drastic decomposition, intense heat release, high thermal risk and difficultly in control. Quantitative classification of different autocatalytic strengths is significant for the formulation of risk control measures and recognition of the most dangerous scenarios in relief system. In this work, the factor, which is the ratio of the heat released by the initial stage to that of the total reaction, has been defined to effectively and quantitatively assess the strength of autocatalytic decomposition based on the Perez-Benito model that includes two-stage competitive reactions. According to "3σ principle" of the normal distribution, the factor was classified into five grades: 0–5%, 5–18%, 18–82% 82–95%, 95–100% corresponding to the autocatalytic strength: strong, less strong, moderate, less weak and weak, respectively. This method is validated using cumyl hydro-peroxide and dicumyl peroxide, the autocatalytic strength of which are well known to be less strong (7.92%) and weak (100%), respectively. The results are consistent with the profile width, heat-quench-reheat test and the isothermal tests. This method was used to classify the autocatalytic strength of dimethyl sulfoxide, 29.5 mass% nitro-guanidine aqueous solution, and Benz aldoxime. The results show that the autocatalytic strengths of these three materials are strong (0.01%), moderate (31.52%) and less weak (82.67%), respectively. Through the classification assessment, it helps to get a more intuitive understanding of the degree of substance danger from the perspective of kinetics and thermodynamics. [ABSTRACT FROM AUTHOR]

Triple one‐way and two‐way shape memory polymers (1W‐SMPs and 2W‐SMPs) are highly desirable for many practical applications due to the multiple shape transformation. In this work, the blend with co‐continuous structure is fabricated based on poly(ethylene‐co‐vinyl acetate) (EVA) and poly(ε‐caprolactone) (PCL), which shows excellent triple one‐way and two‐way shape memory properties. It is found that the blends have two independent crystallization peaks and two independent melting peaks. With the increase of dicumyl peroxide (DCP) content, the crystallization temperature, melting temperature, and crystallinity of both EVA and PCL in the blends gradually decreases. The blends show great dual and triple one‐way shape memory property, and the phenomena of elongation induced by oriented crystallization and contraction induced by melting are clearly seen. Moreover, the blends exhibit remarkable and recyclable triple two‐way shape memory performance, with an average shape recovery magnitude of 97.3% and an average actuation magnitude of 50.6%. In terms of the excellent triple one‐way and two‐way shape memory performance, the EVA/PCL blends may have potential applications in the fields of soft robotics, actuators, and cranes. The new preparation method of triple 2W‐SMPs can be used to fabricate other triple 2W‐SMPs with commercial polymers. [ABSTRACT FROM AUTHOR]

In composite materials, two or more different components are combined to produce a new material with different characteristics from the individual components. In recent years, due to environmental concerns, the development of biocomposites based on natural fibers has attracted great interest of researchers. The mechanical properties of biocomposites are dependent, among other parameters, on matrix properties, fiber properties as well as fiber/matrix adhesion. There are different approaches to improve fiber/matrix adhesion, such as, the use of fiber surface treatments and the use of matrix modifiers, i.e.,: coupling agents. In this work, poly(lactic acid) matrix composites reinforced with two different lignocellulosic fibers (sisal and flax) were prepared and the mechanical properties of both types of composites were compared. On the other hand, poly(lactic acid) polymer was modified with maleic anhydride in the presence of dicumyl peroxide. The mechanical properties of PLA/lignocellulosic fiber composites modified with maleic anhydride-modified poly(lactic acid) were also studied. [ABSTRACT FROM AUTHOR]

The work was aimed at the investigation of influence of peroxide curing system on cross-linking and properties of rubber compounds based on SBR. First, the temperature of vulcanization and the amount of dicumyl peroxide on curing process and physical-mechanical properties were investigated. Then, co-agents Type I and Type II were added to the rubber formulations cured with peroxide. The results revealed that the increase in temperature leads to the acceleration of curing process while both, curing kinetics and physical-mechanical properties were influenced by the amount of peroxide. The application of Type I co-agents resulted in the acceleration of curing process and increase in cross-link density of vulcanizates, which was reflected in the increase of hardness and decrease of elongation at break. The influence of Type II co-agents on curing kinetics was negligible, while most of them caused the reduction in cross-linking degree of vulcanizates. Type I co-agents contributed to the improvement of tensile strength of vulcanizates, while the influence of Type II co-agents on tensile strength was of minor importance.

Blends of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) were compounded in the presence of dicumyl peroxide (DCP) to improve the compatibility and foaming capabilities. PLA/PBS blends with a weight ratio of 40/60 and DCP contents of 0, 0.1, 0.4 and 1 wt% were analyzed. Blends and neat materials were foam injection molded using azodicarbonamide as a chemical foaming agent. The thermal and rheological behaviors of materials are discussed. The morphologies and mechanical responses of the foamed samples are compared and analyzed. The best blend results were obtained with 0.1 wt% of peroxide, reaching impact strength values similar to those of neat-foamed PBS and cell population densities higher than neat PLA. Peroxide contents higher than 0.4 wt% tend to decrease the performance of the blend due to excessive crosslinking.

The metal-free oxidative alkene methylation/alkynylation of 1,4-enyn-3-ols with an organic peroxide as the methyl source has been developed, which provides straightforward and practical access to the challenging quaternary-carbon-containing but-3-yn-1-ones. The method is reasoned to go through methylation of functional alkenes utilizing dicumyl peroxide as the methylating reagent and subsequent intermolecular cyclization/1,2-alkynyl migration. This reaction has an excellent functional group tolerance, broad substrate scope, and exquisite selectivity. [ABSTRACT FROM AUTHOR]

Blending of poly (lactic acid) (PLA)/functionalized gum arabic (FG) in presence of dicumyl peroxide (DCP) presents a simple process to produce film using melt extrusion (recycle time ~ 4 min, screw speed ~60 rpm) at 180°C with tailored characteristics. The FTIR investigation shows that the confirmation of grafting of PLA chains on FG through formation of new C─C linkage. Properties of fabricated films such as morphological, mechanical, UV barrier and contact angle are examined to develop film with improved interfacial interaction, increased toughness, UV–C blocking effect (~95%) and hydrophobicity (~14%). Polarized optical microscopy (POM) studies reveal that PLA/1FG with and without DCP has more crystal density as compared to PLA at 120°C. This melt extrusion permits straightforward, feasible bionanocomposite film and has great potential as a modification with DCP assists to overcome particular drawbacks of FG. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of incorporating chemical agents with green polyethylene terephthalate (PET) bottles on extrudate color change and other properties. First, the best type of chemical agent that decolorizes recycled green PET bottles (RGPB) with good processability was determined. RGPB-chemical agent mixtures were evaluated, reducing, photoinitiator, or oxidant, where the best one turned out to be the oxidizing agent, a dicumyl peroxide. Then new mixtures of RGPB-oxidizing agent, dicumyl or benzoyl, were made in a reactive extrusion process employing a drying hopper to avoid hydrolytic degradation. The intrinsic viscosity, crystallinity, and color change of extrudates were determined. It was determined by SEM with EDS that the dye is possibly a chlorinated copper phthalocyanine. The final results show an increase in the intrinsic viscosity of the PET handling dicumyl peroxide, a partial whitening of the extrudates, and an increase in the crystallinity of the PET, which contributed to a decrease the hue and saturation of the green color of RGPB. Where the dicumyl peroxide present in mixtures with RGPB interacts with chlorinated copper phthalocyanine to produce phthalamide or phthalic acid, which are white. [ABSTRACT FROM AUTHOR]

In this study, a new acrylamide monomer containing chalcone group was synthesized and a homopolymer was prepared according to free radical polymerization method in the presence of dicumyl peroxide initiator. In this study, a new acrylamide monomer containing chalcone group was synthesized and a homopolymer was prepared according to free radical polymerization method in the presence of dicumyl peroxide initiator. TGA measurements were taken at different heating rates to examine the thermal properties of the polymer and determine the degradation activation energy. The average activation energy of the one-step degradation polymer was calculated using the Flynn-Ozawa method. Flynn-Wall-Ozawa curves were generated from the comparative TGA curves in the range of 0.02-0.5 transformation, and the average activation energy was determined as 127.03 kJ mol-1. The dielectric properties of the polymer were examined with an impedance analyzer in the frequency range of 1-200 kHz at different temperatures. While the dielectric constant value of the polymer at 1 kHz at room temperature is 7.51, this value decreases towards higher frequencies. The dielectric constant of the polymer at 200 kHz was recorded as 7.33. It was determined that the dielectric constant calculated as 7.44 at 10 kHz fixed frequency at room temperature increased to 10.48 for 50 oC and 14.06 for 60 oC with the increase of temperature. [ABSTRACT FROM AUTHOR]

The development of new ecological materials to promote sustainability is being encouraged. Crosslinked biopolyethylene (BioPE)/noni flour (Morinda citrifolia) biocomposites were prepared using maleic anhydride‐grafted polyethylene (PE‐g‐MA) and dicumyl peroxide (DCP). The biocomposites were processed in an internal mixer and injection molded. Torque rheometry, Izod impact strength, tensile strength, heat deflection temperature (HDT), differential scanning calorimetry (DSC), thermogravimetry (TG), and scanning electron microscopy (SEM) properties were investigated. Torque rheometry curves suggest that the biocomposites did crosslink due to the DCP attack on the BioPE chain. The BioPE/noni flour/PE‐g‐MA formulation with 0.5% and 1% DCP produced a higher level of crosslinking. As a result, the mechanical properties (impact strength, elastic modulus, and tensile strength) were improved. SEM showed fractured noni flour particles in the BioPE matrix with the formation of a tubular structure. The HDT increased, suggesting that the biocomposites exhibit enhanced thermomechanical strength. Furthermore, the biocomposites thermal properties obtained by DSC underwent few modifications. The TG results showed that the crosslinked biocomposites have better thermal stability than the noncrosslinked biocomposites. The crosslinking process of BioPE/noni flour biocomposites with the PE‐g‐MA/DCP hybrid is an effective way to improve the performance of these materials. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) was modified using dicumyl peroxide (DCP) and tetraglycidyl diamino diphenyl methane (TGDDM) to improve its melt viscosity and molecular weight for a variety of industrial applications. The PLA was branched or crosslinked with DCP at 180 °C, and gel content was detected as the DCP concentration was over 0.6 phr. However, for TGDDM, it was observed that only chain extension or branching occurred; the number- and weight-average molecular weights and polydispersity index (PDI) increased. The melt flow index decreased as the concentration levels of DCP and TGDDM increased. However, when the TGDDM was over 0.5 phr, the opposite results were observed. The variations in the mechanical properties of modified PLA were marginal; however, the elongation at break slightly decreased. The onset value of the decomposition temperature of the DCP-modified PLA slightly decreased. In contrast, with TGDDM, the onset value slightly increased. As the branching and crosslinking of the modified PLA increasingly occurred, relatively low relaxation enthalpy was detected. However, the glass transition temperature (Tg) was not influenced. An increase in the storage modulus (G′), loss modulus (G″), and complex viscosity (η*), and a decrease in tan δ at low frequencies showed that the rheological behavior of the modified PLA turned from liquid-like to solid-like because of the modifications achieved using DCP and TGDDM. [ABSTRACT FROM AUTHOR]

To find novel classes of potential fuel additives of multivalent activity, particularly antioxidants, a series of recently synthesized ethyl-6-amino-5-cyan-methyl-4-aryl-4H-pyran-3-carboxylates have been investigated using model oxidative reactions. The compounds studied appear to be prospective inhibitors of hydrocarbons oxidation. Some of them are antioxidants of combined action, breaking the chains of the oxidative reactions with cumene peroxide radicals and catalytically decomposing cumene hydroperoxide. [ABSTRACT FROM AUTHOR]

In this study low-density polyethylene (LDPE)/thermoplastic starch (TPS)/nanoclay (O-Mt) nanocomposites were prepared by a melt blending process using a Brabender mixer. Dicumyl peroxide (DCP) and nanoclay (O-Mt) were studied to improve interfacial adhesion and to obtain the various desired properties of the nanocomposites. The structure and properties of the materials were studied by X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and by tensile and Izod impact tests. X-ray diffraction analysis of the nanocomposites showed that the characteristic peaks of the clay were shifted to the lower angles, indicating an intercalated structure in the presence of dicumyl peroxide (DCP). The TGA curve indicated an improvement in the thermal stability of the materials with the amount of silicate and DCP. The mechanical properties of the materials were improved as a consequence of the increase in phase adhesion which gave an improvement in crystallinity confirmed by DSC. In addition, the impact strength of the modified materials was improved compared to the original materials. A modification of morphology as well as roughness was demonstrated by SEM and AFM. [ABSTRACT FROM AUTHOR]

This paper describes work carried out to assess the effect of fibre treatments and coupling agent on the mechanical performance of PLA composites reinforced with 20 wt% fibre. The chemically-treated harakeke and hemp fibres used to produce fibre mats. Maleic anhydride (MA) grafted PLA (MA-g-PLA) was used as a coupling agent. Composites with fibre treated with silane and dicumyl peroxide (DCP) and composites using MA-g-PLA were characterised by swelling testing, scanning electron microscopy (SEM), tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It was found that the interfacial bonding for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA noticeably improved supported by lower swelling indices, higher tensile strengths and lower tan δ compared to those composites with fibres treated using alkali only, with the highest tensile strength of about 11% higher obtained from composites treated with MA-g-PLA followed by silane and then peroxide. However, using silane, peroxide and MA-g-PLA as additional composite treatments increased significantly the composite failure strain by up 11, 19 and 30%, respectively for harakeke composites and by 13, 24 and 30%, respectively for hemp composites. [ABSTRACT FROM AUTHOR]

The presented research reports a successful preparation of a super toughened poly(lactic acid)/poly(ethylene vinyl acetate) (PLA/EVA) blend using simultaneous dicumyl peroxide (DCP)‐induced dynamic vulcanization and addition of hydrophobic spherical silica nanoparticles (NPs). The torque evolution during melt mixing of the samples was assessed to track the dynamic vulcanization process. NPs were localized mainly in the EVA droplets and at the interface where a layer of particles was formed with a small amount dispersed in the PLA matrix. The incorporation of NPs or DCP induced compatibilization, causing a drastic decline in the size of EVA droplets in addition to improving the interfacial adhesion. On the other hand, simultaneous dynamic vulcanization and NPs incorporation synergistically affected the compatibilization of EVA and PLA phases. Differential scanning calorimetry (DSC) was employed to analyze the thermal transition and crystallization behavior of the samples. Simultaneous incorporation of silica nanoparticles and DCP at an optimum content significantly improved the tensile toughness, elongation at break, and impact strength, giving rise to super toughened PLA/EVA blend. The elongation at break and impact strength of the dynamically vulcanized PLA/EVA blend containing 5% nanosilica showed an increase from 7% to 175% and 5.1 to more than 77 kJ/m2, respectively as compared to the neat sample. Based on SEM analysis of the fractured surface of the tensile samples, cavitation in combination with intensive shear yielding of the matrix were dominating toughening mechanisms. Finally, the effect of DCP and NPs on the microstructural properties of the sample was investigated through rheological evaluations. [ABSTRACT FROM AUTHOR]

An efficient protocol for the synthesis of ring‐fused quinazolinone derivatives through hydroxyalkyl radical‐initiated cyclization was developed, providing a series of five‐ and six‐membered ring‐fused hydroxyl‐containing quinazolinones in moderate to good yields. This reaction was conducted under metal‐free conditions using dicumyl peroxide as the radical initiator. Notably, this is the first example of the construction of ring‐fused quinazolinones through the radical C(sp3)−H functionalization of simple alcohols and was successfully utilized in the synthesis of Phaitanthrin A derivative. [ABSTRACT FROM AUTHOR]

The blend of standard Indonesian rubber (SIR-3L) and low density of polyethylene (LDPE) with a ratio of 50/50 (w/w%) had been prepared by varying the amount of divinylbenzene (DVB) and dicumyl peroxide (DCP). The properties of SIR-3L/LDPE blends had been characterized using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and mechanical properties. The addition of divinylbenzene and dicumyl peroxide affected the properties of SIR-3L/LDPE blends. [ABSTRACT FROM AUTHOR]

In the present work, barium ferrite in constant loading was dosed to the rubber matrices based on NR, SBR and NBR. Sulfur, peroxide and mixed sulfur and peroxide curing systems were applied for cross-linking of rubber magnetic composites. The application of sulfur or peroxide curing system leads to the formation of different types of linkages between rubber chain segments. As the structure of the formed cross-links plays a significant role in determining the final properties of rubber articles, the main aim of the work was to use the combination of curing systems in order to suppress the disadvantages of both systems and possibly to highlight their benefits. The results showed that composition of curing system has considerable influence on cross-link density of composites, which was subsequently reflected in typical change of physical-mechanical properties and glass transition temperature. The tensile strength was improved with increasing amount of peroxide curing system. The reason can be attributed to the presence of co-agent zinc methacrylate, which exhibits strong adhesion to magnetic filler and thus it contributes to the improvement of compatibility and homogeneity on the interphase filler–rubber. On the hand, there was observed no influence of curing system composition or type of rubber matrix on magnetic characteristics of composites. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation of the influence of the aluminum-powder concentration on the thermomechanical characteristics of the composites based on the high-density polyethylene. We show that use of a compatibilizer—maleic anhydride–polyethylene graft copolymer—in a mixture with high-density polyethylene has an influence on the regularity of variation of the thermomechanical curves. We study the influence of various cross-linking agents (dicumyl peroxide and sulfur) on the thermomechanical properties of composites. At a particular dicumyl peroxide and sulfur concentration, the composites might reside in three physical states: solid, highly elastic, and viscous flow. [ABSTRACT FROM AUTHOR]

The chemical modification of commodity polymers such as polyethylene (PE) is a versatile synthetic approach for preparing materials that cannot be manufactured cost‐effectively using conventional polymerization techniques. Aiming to improve PE character low contents of dicumyl peroxide (DCP), from 0% to 1.5% was added as crosslinker to an industrial batch (PEs mixture and additives). From tensile testing crosslinking provided higher elastic modulus most due to the restrained microstructure where XPEs macromolecular chains are interconnected also providing lower strain at break. Crosslinking effects on the nonisothermal melt crystallization rate (Cmax) and degree of crystallinity (Xc) were evaluated; Cmax increased with the cooling rates, whereas Xc increased upon DCP addition. The melt crystallization kinetics were thoroughly investigated applying Pseudo‐Avrami, Ozawa, and Mo models. Ozawa failed to describe the crystallization most due to ignore the secondary crystallization and spherulites impingement at the end of crystallization while Pseudo‐Avrami and Mo provided quite good fits. The activation energy was computed using Arrhenius' approach, crosslinked compounds presented higher energy consumption, whereas exception was verified for 0.5XPE which displayed the lowest energy and overall the best mechanical performance this is the most proper compound for industrial applications, such as packaging, and disposables as well as general goods. [ABSTRACT FROM AUTHOR]

In this work, different contents (0.25, 0.50, 0.75, and 1 phr) of dicumyl peroxide (DCP) are incorporated into the bio‐based high‐density polyethylene (bioPE)/kraft lignin (KL) blends with a composition of 80 and 20 wt%, respectively with the aim of improving overall performance. The samples are obtained by reactive extrusion and injection‐molding process, and then their overall performance is assessed by tensile tests, thermal analysis, optical and surface appearance, and wettability studies. The obtained mechanical properties confirm the successful interaction between bioPE and KL due to the addition of organic peroxide, which plays a key role in compatibilization. In particular, bioPE/KL blends with 1 phr of DCP achieve an increase in elongation at break of about 300% together with a noticeable increase in the impact strength of about 29% higher than the uncompatibilized bioPE/KL blend, while the tensile modulus decreases 42%. In addition, images obtained by field emission scanning electron microscopy show that the presence of DCP in the blends enhances better dispersion of KL into the bioPE matrix. The wettability analysis indicates that KL and DCP affect the hydrophobicity of the neat bioPE. Therefore, the resultant blends can be considered as potential sustainable polymers with balanced properties. [ABSTRACT FROM AUTHOR]

The dielectric properties of chicken feather fibre-natural rubber (CF-NR) composites have been studied at varying frequencies. The effects of alkali treatment, thermal treatment and a three-component dry bonding agent consisting of hexamethylenetetramine, resorcinol and nano silica (HRS) on these properties were studied. Dicumyl peroxide (DCP) and sulphur were used as curing systems in the preparation of the composites. Fibre filled composite systems have higher values of dielectric constant than the gum (unfilled) sample. This is due to the polarization exerted by the addition of fibres into the matrix. The dielectric constant decreases with frequency due to the dropping out of dipolar and interfacial polarization at higher frequency. The dielectric constant values of composites containing alkali treated chicken feather fibres (ACF) were higher because of the increase in number of polar groups after the treatment. The carbonized chicken feather fibre (CCF) incorporated NR composites have highest dielectric constant values because they consist of conducting material in an insulating matrix which leads to interfacial polarization. The dielectric constants of sulphur cured composite samples are higher than the corresponding DCP cured ones. The addition of fibres and with the incorporation of the bonding agents causes an increase in the dielectric constant and decreases the volume resistivity of the composites. [ABSTRACT FROM AUTHOR]

Crosslinking of polyolefin elastomer (POE, ENGAGE™ 8480) with Dicumyl Peroxide (DCP) can have effects on its crystallization dynamics, crystal structure, and properties. The POE crosslinked uniformly has significantly lower crystalline ability than the one with only amorphous phase crosslinked, which, in turn, has weaker crystalline ability than neat POE. The crystallinity and melting point depend on how the POE is crosslinked. The neat POE and POE crosslinked in amorphous phase only, are investigated with DSC and in‐situ tensile/synchrotron radiation (WAXD/SAXS). In situ tensile/synchrotron X‐ray during a uniaxial stretching process indicates that severe crystal fragmentation is observed at a strain around 45%, and with further increase in strain. The stress in the crosslinked POE is significantly larger than neat POE. For both samples, crystal orientation increases sharply within the strain range up to 88% where orientation‐induced new crystals aligned in stretching direction are observed. The long period increases more in stretching direction for the crosslinked POE, consistent with larger stress in this sample, and the stress difference is more pronounced at large strains (27.3 vs. 10.9 MPa at a strain 435%). Permanent set of the crosslinked POE is smaller, consistent with less oriented crystals observed after the test for permanent set. [ABSTRACT FROM AUTHOR]

Dynamic vulcanized thermoplastic polyurethane (TPU)/methyl vinyl silicone rubber (MVQ) thermoplastic vulcanizates (TPVs) were prepared in torque rheometer. The influence of the type and amount of peroxide crosslinking agent on the mechanical properties, thermal stability, micromorphology and melt flowability was systematically investigated. The results showed that the mechanical properties of the TPVs vulcanized by 2,5‐dimethyl‐2,5‐di (tert‐butyl peroxy) hexane (DBPH) first increased and then decreased with increasing the peroxide amount, while for dicumyl peroxide (DCP) vulcanizing system the mechanical properties slowly increased. Besides, the comprehensive mechanical properties vulcanized by DBPH were better than those of DCP group. The results of the thermogravimetric analysis showed that the TPVs vulcanized by DBPH had better heat stability, corresponding to the excellent thermo‐oxidative aging performance and the 38% increase in tensile strength after aging. In addition, the MVQ rubber particles showed better dispersing performance for DBPH vulcanizing system. The melt flow rate of the TPVs showed a linear relationship with increasing DBPH dosage and became worse after the amount of crosslinking agent exceeded 1.5 phr. By comprehensive comparison, the TPVs have better performance when use peroxide DBPH as the crosslinking agent and the dosage is 1.5 phr. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation of the effect of bentonite concentration on the main physical and mechanical properties of nanocomposites in elastoplasts based on a mixture of random polypropylene with nitrile–butadiene rubber of various types. To improve the compatibility of the mixed components, a graft copolymer of polypropylene with maleic anhydride is used as a compatibilizer. The mechanism of compatibilization of the graft copolymer in the boundary region, in the zone of contact between random polypropylene and nitrile–butadiene rubber, is considered. The optimal concentrations of cross-linking components at which it is possible to obtain dynamically vulcanized nanocomposites is determined. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Fabrication of core-cross-linked polymeric nanoparticles by incorporating catalytically active diaryl ditelluride. • Ditelluride-containing nanoparticles exhibit dual redox-responsiveness to both oxidants and reductants. • Nanoparticles demonstrate haloperoxidase-mimic activity and catalyze the preparation of organohalides. • Nanoparticles exhibit enhanced glutathione peroxidase-mimic activity using a hydrophobic thiol substrate and cumene peroxide. Polymeric nanoparticles with peroxidase-like enzyme mimetic activity were developed by incorporating catalytically active tellurium (Te) functionalities into cross-linked block copolymers. Bis(2-aminophenyl) ditelluride was used as a cross-linker to react with a diblock copolymer bearing pendent activated ester groups to generate of core-cross-linked nanoparticles (DiTe-NP) containing diaryl ditelluride bonds. DiTe-NP nanoparticles exhibit dual redox-responsiveness inherited from the sensitivity of ditelluride to both oxidants and reductants. When DiTe-NP nanoparticles were treated with H 2 O 2 , the oxidation of the ditellurides triggered the cleavage of Te-Te bonds to form Te(IV)-associated species. The oxidation-responsiveness endows DiTe-NP nanoparticles with haloperoxidase (HPO)-mimic activity. With NaBr and hydrogen peroxide, they catalyzed the oxidative bromination of phenol red, bromolactonization of 4-pentenoic acid, and bromination of 1,3,5-trimethoxybenzene due to the in-situ generation of hypobromous acid (HOBr) for halogenations. These ditelluride-containing nanoparticles also exhibited glutathione peroxidase (GPx)-like activity and accelerated the reduction of hydroperoxide by a thiol substrate. The cleavage of ditelluride bonds by a thiol substrate leads to the formation of key intermediates in the catalytic cycle of DiTe-NP nanoparticles. DiTe-NP nanoparticles showed enhanced activity for the reduction of hydrophobic cumene peroxide by 4-nitrothiophenol. These dual redox-responsive ditelluride-containing nanoparticles are promising candidates as peroxidase mimetics to apply as catalysts for green halogenation reactions and decompositions of toxic peroxides. [ABSTRACT FROM AUTHOR]

This study presents the in-situ rubber nanofibrillation of high-density polyethylene (HDPE), metallocene based polyolefin elastomer (POE) composites employing spunbond technology. The process commenced with the grafting of vinyltrimethoxysilane (VTMS) onto POE chains, a crucial step to preserve the fibrillar structure. Two distinct peroxide initiators, dicumyl peroxide (DCP) and di (t -butyl) peroxide (DTBP), were employed to initiate the grafting reaction. Results from gel content and melt flow index tests demonstrated that DTBP performed more effectively as an initiator than DCP. The grafted elastomers were then incorporated into the HDPE matrix using spunbonding. Subsequently, the fibrillated POE-g-VTMS were crosslinked using moisture to preserve the morphology. Scanning electron microscopy (SEM) images showed the generation of crosslinked nano-scale size POE-g-VTMS fibers in the range of 50–125 nm. Based on the rheological data, drawn crosslinked POE-g-VTMS phase formed an interconnected network, resulting in a remarkable increase in viscosity and storage modulus at the low-frequency range. Additionally, the stretched samples exhibited noticeable strain-hardening behavior at specific extension rates. Notably, this in-situ fibrillation process significantly enhanced HDPE's foaming ability, evident in decreased cell size and increased cell density. Tensile test results conducted at room temperature and subzero temperature (−40 °C) also suggested a substantial enhancement in the elongation at break of the HDPE nanofibrillated composites compared to the unstretched samples. [Display omitted] [ABSTRACT FROM AUTHOR]

Active ester hardeners are a unique class of epoxy hardeners that undergo a curing reaction without generating secondary hydroxyl groups. This characteristic enables the production of low dielectric and low moisture absorption epoxy resins. In this study, two active ester hardeners, bisphenol A diisobutyrate (DIB) and bisphenol A dimethacrylate (DMA), were used to prepare epoxy resins by reacting with a resveratrol-based epoxy monomer (REP). By cross-linking the double bonds in the resin (using dicumyl peroxide, DCP), the properties of the resin can be dramatically changed. Among the resins prepared, REP/DMA/DCP exhibited the highest cross-linking density, approximately 48 times that of REP/DIB. Its storage modulus at 300 °C remained at 600 MPa, indicating an equivalent glass transition temperature (T g) higher than 300 °C. Additionally, the cross-linking of the ester side groups increased the initial degradation temperature by 12–13 °C, reaching 395–396 °C. Regarding the coefficient of thermal expansion (CTE), the cross-linking of ester side groups had no significant effect on the CTE in the glassy state. However, it drastically reduced the CTE above the glass transition temperature. The average CTE (30–300 °C) of REP/DMA/DCP was only 106 ppm/°C. Furthermore, the cross-linking of the ester side groups appeared to reduce the dielectric constant but increased the dielectric loss and the water absorption rate. Nevertheless, REP/DMA/DCP's dielectric constant at 10 MHz of 3.07, dielectric loss of 0.01, and saturated water absorption of 0.77 wt% remain in the low range. [Display omitted] • Ultra-high cross-linked epoxy resins were prepared by cross-linking double-bonds. • The effect of whether or not the side groups were cross-linked was investigated. • Cross-linking of ester side groups improved the thermal stability of epoxy resins. • Equivalent T g for REP/DMA/DCP can be considered higher than 300 °C. [ABSTRACT FROM AUTHOR]

In this work, a novel grafted film with both antimicrobial and antioxidant properties was developed. ε-polylysine (EPL) and caffeic acid (CA) were used as raw materials, and EPL-CA was synthesized by grafting CA onto EPL by the carbodiimide coupling method. Using dicumyl peroxide (DCP) as a radical initiator, EPL-CA was crosslinked with low-density polyethylene (LDPE) by reactive co-extrusion to produce grafted films with both antimicrobial and antioxidant properties. Compared with pure LDPE film, all graft films show antimicrobial and antioxidant properties. Specifically, when the EPL-CA concentration is >3%, the inhibition rates against Escherichia coli (>91%) and Staphylococcus aureus (>97%) significantly increase, and the DPPH free radical scavenging rate (>60%) also significantly increases. Compared with the control film, the grafted film exhibits increased tensile strength and decreased elongation at break. In addition, the migration levels of all graft films in food simulants are below the migration standards set by the European Union. Overall, immobilizing EPL-CA on the LDPE matrix improves antimicrobial, antioxidant, and mechanical properties. Among them, the film exhibits the best comprehensive performance when the EPL-CA content is 3%. Therefore, the development of antimicrobial and antioxidant active LDPE film is proposed. These results indicate that active packaging films can be prepared through reactive extrusion, a promising and industrializable technology, and have broad prospects in improving food safety and other aspects. [Display omitted] • ε-polylysine is functionalized with caffeic acid by carbodiimide coupling. • Low density polyethylene is grafted with caffeic acid functionalized ε-polylysine. • The composite film was prepared by reaction co-extrusion technology. • The prepared films exhibits antibacterial and antioxidant functions. [ABSTRACT FROM AUTHOR]

To address the challenge of dispersing as well as reacting a filler with an incompatible natural rubber (NR) system and enhance material properties, this study explores melt grafting technique (e.g., in-situ reactions) to incorporate epoxidized-NR (ENR) into the lignin/NR system. The process involves melt-mixing (high temperature and shear forces) of ENR and lignin with dicumyl peroxide (DCP) acting as an initiator. The results illustrate the successful formation of covalent grafts between ENR and lignin through the opening of epoxy rings and shear-temperature-mediated etherification, facilitated by the peroxide initiator. Employing the ENR-lignin blend as a filler masterbatch, NR composites were developed, varying the lignin concentrations (0 to 50 phr) in the rubber. Remarkably, the NR composite formulation with 20 phr lignin exhibited significantly enhanced mechanical properties, which remained robust even after exposure to UV, humidity, and elevated temperature. [Display omitted] • Controlled reactive mixing resulted in covalent grafting of epoxidized rubber onto lignin. • Lignin – ENR was successfully utilized as a functionalized masterbatch filler of rubber. • Natural rubber -ENR – lignin composites provided superior mechanical properties. • Reactive melt mixing avoids the use of solvents or down stream processes. [ABSTRACT FROM AUTHOR]

A formation mechanism of crystal defects was proposed by investigations about the factors affecting the formation of macroscopic defects in dicumyl peroxide solution. The effects of crystallization parameters such as the solvent, temperature and supersaturation on the formation of crystal defects were studied in a targeted manner. A mild crystallization environment was beneficial to reduce the formation of defects during the crystal growth process. A self-made device was designed to study the effect of gas bubbling on the growth of dicumyl peroxide crystals. Experiments indicate that degassing of the solvent will lead to a sharp drop in the crystal growth rate and reduce the liquid inclusions inside the crystal. The enrichment of carbon dioxide in the solution was conducive to the formation of macroscopic defects. Through hot-stage optical microscopy, it can be proved that the fluid inclusions will transform into "negative crystals" when heated. Through molecular dynamics simulation on the surface structure and the adsorption mechanism, it is found that during the crystal growth process, the rapid growth of some of the dicumyl peroxide crystal faces and the adsorption of impurity particles may be the main reasons for the formation of liquid inclusions. [ABSTRACT FROM AUTHOR]

Grafting of polylactide (PLA) onto the cellulose nanofiber (CNF) (CNF‐g‐PLA) was prepared by in situ reactive extrusion using dicumyl peroxide (DCP) as a free radical initiator to improve the interfacial adhesion between CNFs and PLA. The effect of DCP content on the dynamic rheological properties, crystallization behavior, mechanical properties, and micromorphology of PLA/CNF (95/5) bionanocomposite was systematically investigated. FTIR spectra confirmed that PLA chains were successfully grafted onto the CNF surface by forming CC bonds. The presence of such CC crosslinks improved stress transfer at the CNF–PLA interface; SEM and TEM observations and adhesion factor calculated from DMA data confirmed that the synthesized graft copolymers improved the interfacial interaction between CNFs and PLA matrix, thus enhancing the mechanical properties of CNF‐g‐PLA nanocomposites. Compared with PLA/CNF (95/5) bionanocomposite, the maximum tensile modulus, tensile strength, elongation at break, and V‐notched Izod impact strength of CNF‐g‐PLA nanocomposites were increased by 31.8%, 20.0%, 12.0%, and 27.9%, respectively. WAXD and DSC analyses indicated that the crystallinity degree of the grafted CNF‐g‐PLA was higher than that of PLA/CNF (95/5) bionanocomposite, and first increased and then decreased with increasing DCP content. The polarized optical micrographs confirmed that DCP‐initiated grafting significantly increased the nucleation density but decreased the spherulite size of PLA. The melt strength of CNF‐g‐PLA nanocomposites was improved due to stronger intermolecular interaction by grafting. This one‐step in situ reactive extrusion technology provides an efficient and economical way to enhance the properties of PLA/CNF bionanocomposites. [ABSTRACT FROM AUTHOR]

The management of reactivity hazards has long been a problem in chemical process and the indexing approach is believed to be an effective solution. However, while most of the reactivity indexes do not consider the runaway scenario and are often quite rough, the assessment criteria used to judge thermal runaway does not take the type of scenario or the severity of the consequences into account. At present, there are no index system that can represent the reactivity hazards in chemical process comprehensively. Therefore, this paper has developed a hazard index for reactivity management (HIRM) in chemical processes. The reactivity hazards could be identified, evaluated and managed through nine steps defined by this method. The HIRM method is able to assess various runaway scenarios and quantify the reactivity hazards based on the consequence and probability. The consequence is rated by the damage radius which represents the damage level caused by fire, explosion, and toxic release due to reaction runaway. The probability indicates the initial event frequency, the initiation time and the controllability of the entire runaway process. The reactivity risks could then be classified by the HIRM index uniformly and comprehensively, with methods to manage the risks proposed. Six sets of equipment in the dicumyl peroxide (DCP) production unit was used as an example to demonstrate the construction of the HIRM index system. The results showed good agreement with the actual risk distribution, meaning that the HIRM method is an effective tool for the management of reactivity hazards in chemical process. [ABSTRACT FROM AUTHOR]

The present study involved valorisation of rice straw (RS) in the form of rice straw flour (RSF) for the fabrication of poly (butylene succinate) (PBS) based bio-composites through a melt extrusion method, using dicumyl peroxide (DCP) as the cross-networking agent, and study of the morphological, thermal, mechanical and rheological behaviours of the extruded bio-composites. A layered like morphology with good dispersion of RSF in the PBS matrix was observed from X-ray diffraction and field emission scanning electron microscopic analysis. Thermo gravimetric analysis showed that the incorporation of RSF improved the thermal stability of PBS, whereas the value of the different thermal properties i.e. glass transition temperature (Tg), melting temperature (Tm) remained almost identical. Addition of DCP (2 wt%) into the PBS-RSF systems increased both the tensile strength and elongation at break (EB) (%) values. Rheological investigation of the bio-composites showed that the storage modulus (G') was less than the loss modulus (G") over the angular frequency (ω) range until crossover, corroborating the viscous behaviour of the samples. The complex viscosity, η' was constant when ω was less than 1 rad/s for all the samples, showing Newtonian characteristics. Shear thinning behaviour was observed when ω was greater than 1 rad/s. Furthermore, no phase separation was observed from the Han plot and good compatibility was noticed from the Cole–Cole plot, which signifies good rheological properties of the fabricated bio-composites. [ABSTRACT FROM AUTHOR]

Acrylonitrile‐butadiene‐styrene (ABS) functionalization is industrially important since it can wide the ABS application range. However, grafting of functional groups must be effective. This work aimed evaluating the effectiveness of ABS functionalization in an internal mixer, using maleic anhydride (MA) and dicumyl peroxide (DCP) as initiator, at 2.5% and 5.0%; and 0.3% and 0.5% contents respectively. Torque rheometry, melt flow rate (MFR), titration, Fourier transform infrared spectroscopy (FTIR), contact angle, thermogravimetry (TG), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD) were used to collect the main parameters of produced compounds. For ABS with 5% MA and 0.5% DCP, an efficiency of 62% was reached with the degree of grafting 3.1% MA. FTIR spectra confirmed new band in ABS chain in 1780 cm−1 due to the carbonyl group. Reduction in contact angle and thermal stability were verified, whereas MFR and torque rheometry suggested that viscosity decrease is most due to the molecular weight reduction. In general, MA grafted ABS presented proper functionalization with great potential for applications as reactive compatibilizer. [ABSTRACT FROM AUTHOR]

An efficient protocol for obtaining fused quinazolinones through an oxidative free-radical cyclization under metal- and tin-free conditions is described. The oxidative cyclization of various N -3-ω-iodoalkyl derivatives to provide tricyclic systems using dicumyl peroxide as the sole reagent is studied. The method then is employed for the syntheses of 5-, 6-, and 7-membered fused quinazolinone analogues, including the natural products deoxyvasicinone and mackinazolinone. A xanthate-based oxidative radical cascade addition/cyclization process that allows the production of new menthol- and testosterone-quinazolinone conjugates, as well as the first total synthesis of leucomidine C, are also reported. [ABSTRACT FROM AUTHOR]

A novel and facile copper-catalyzed methylation of sulfonamides was herein demonstrated. The practical transformation took place readily under the oxidative conditions, and N-methyl amides (23 examples) were successfully furnished in high efficiency (up to 90% yields). Dicumyl peroxide was considered to act not only as the oxidant in the system, but also methyl donor for the methylation protocol. [ABSTRACT FROM AUTHOR]

In this paper, ethylene–vinyl acetate–glycidyl methacrylate terpolymer elastomer (EVM–GMA) was vulcanized by methyltetrahydrophthalic anhydride (MTHPA) and cross-linked by dicumyl peroxide (DCP) as a reference. Mechanical properties and hot-air aging properties were investigated. The cross-linking mechanism of EVM–GMA reacting with MTHPA was proposed, and a "model vulcanization reaction' was designed to prove its rationality. The reaction products were characterized by GPC, FT-IR, GC–MS, 1H-NMR and so on. The results indicated that the cured torque MH − ML and cross-link density of EVM–GMA increased first and then decreased with the increase in amount of MTHPA. An optimum of curing, mechanical properties and aging resistance were found at a molar ratio of anhydride to GMA of 1:2. The MTHPA curing reaction catalyzed by tetrabutylammonium bromide was faster compared to the selected DCP cure system, and the mechanical properties, compression set and hot-air aging performance were superior as well. The "model vulcanization reaction" indicated that one molecule of MTHPA successfully reacted with two molecules of the mono-epoxy compound of glycidyl–versatic ester (E10P) to form a hydroxyl-terminated epoxy–anhydride–epoxy polyester structure. Therefore, one molecule of MTHPA can "bridge" two epoxy side groups (provided by GMA) on the adjacent molecular chain of EVM–GMA to realize rubber cross-linking, which proved that the cross-linking mechanism based on epoxy–anhydride reaction for EVM–GMA elastomer proposed in this paper was reasonable. [ABSTRACT FROM AUTHOR]

The effect of Joncryl ADR®-4368 (abbreviated ADR) and dicumyl peroxide (DCP) on poly(butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) blend was investigated. Two different blending procedures were adopted: (1) one-step blending of all components for 8 min; (2) premixing of PBAT and ADR (or DCP) for 4 min followed by addition of PLA blending for 4 min. ADR and DCP were effective compatibilizers for the PBAT/PLA blend by one-step blending which were confirmed by improving the phase interface between PBAT and PLA, decreasing the dispersed phase size, increasing the elasticity, viscosity and tensile strength. Moreover, the addition of ADR into PBAT/PLA blend by two-step blending was more efficient than the one-step blending based on refined morphology and further increased tensile properties. The two-step blending was beneficial to produce a larger amount of PBAT-graft-PLA (PBAT-g-PLA) copolymers at the phase interface. However, DCP was added to the PBAT/PLA blend by the two-step blending which showed lower properties than one-step blending. DCP triggered free branching reactions in a fast way. Based on the character of compatibilizers, choosing properly blending procedures can enlarge the tensile properties. These results would be interesting for industrial polymer materials, and may be importance to the wider practical application of PBAT/PLA blends. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the elastic recovery of EPDM samples crosslinked either by a phenolic resin (resol) or by a radical peroxide (dicumyl peroxide, DCP). From compression set experiments, it was observed that radically crosslinked EPDMs have better elastic recovery properties. On the other hand, for the same crosslinking density, radically crosslinked EPDM shows better compression set than EPDM crosslinked with phenolic resins. The Chasset-Thirion equation was then used to successfully fit the experimental relaxation curves. As a notable result, the preferential statistics of a peroxide-crosslinked network over a phenolic resin (resol) showed that better elastic recovery properties were obtained. Finally, the influence of fillers (carbon black and silica) was also studied. Carbon black with DCP crosslinking was shown to improve elasticity recovery whereas silica fillers lead to worse properties. It was then assumed that the interaction between particle surface and a voir comme dans autre publi à modifier ce crosslinking agent induced crosslinking gradients in the inter-particle volume. [ABSTRACT FROM AUTHOR]

[Display omitted] Crystalline triphenyltin cumyl and tert-butyl peroxides (Ph 3 SnOOCMe 2 Ph and Ph 3 SnOOBut, respectively) and triphenyllead cumyl peroxide (Ph 3 PbOOCMe 2 Ph) were synthesized and characterized by single crystal and powder X-ray diffraction, NMR, FTIR and Raman spectroscopies, TG and DSC analysis. The formation of triphenyltin tert-butyl peroxide in benzene in the presence of a base was proved by 119Sn, 13C and 1H NMR spectroscopy. To the best of our knowledge, the obtained complexes are the first structurally characterized coordination compounds of tin and lead with organic peroxides. [ABSTRACT FROM AUTHOR]

The polymerization industry has existed for many years. The advancement of industrial technology is contributed to the related synthesis and application of enduring polymer operation. Organic peroxide (OP) initiators have been used and applied to practical industrial processes which may cause a runaway reaction due to their self-reactive property. OPs have been used for a long time and studied in the related literature. However, there are still emerging OPs that have recently been applied to these processes, and there are few related studies. To ensure the thermal safety of OPs in the process of production, transportation, and storage, the common OP initiator such as dicumyl peroxide (DCPO) was selected to be investigated. First, thermal decomposition characteristics under non-isothermal and adiabatic conditions of DCPO were acquired by differential scanning calorimetry. Second, combined calorimetry with pseudo-adiabatic and isothermal conditions can determine the process of thermal hazards and basic reaction patterns. The gleaned data can input into a mathematical model to evaluate the basic thermal hazards for DCPO, respectively. In addition, based on simulated thermal explosion models and kinetic parameters, hazardous properties of storage and transport can also be acquired. The results show that the DCPO has prominent hazard properties on thermal and explosive hazards in process conditions which should pay much attention to temperature during storage and transportation. [ABSTRACT FROM AUTHOR]

A radical cascade sulfuration/cyclization of o‐cyanoarylacrylamides with dicumyl peroxide as an oxidant and thiols as coupling partners has been developed. This reaction was conducted under simple conditions and showed wide substrate scope, affording the corresponding products in good chemical yields. This work provides a new and efficient strategy for the preparation of 3‐thiomethylated quinoline‐2,4‐diones. [ABSTRACT FROM AUTHOR]

This work studied the properties of poly(lactic acid) (PLA) and chemically crosslinked poly(lactic acid) (CrPLA) in the presence of different types of silica (SiO2): SiO2 from rice husk ash (RhSiO2) and commercially available SiO2 (CoSiO2). A mixture of triallyl isocyanate and dicumyl peroxide was used as a chemical crosslinking agent. The rice husk was burnt in a furnace to extract RhSiO2. The thermal and mechanical properties of the PLA and CrPLA composites were investigated as a function of the SiO2 content. The presence of C–H functional groups supports the compatibility of stearic acid and RhSiO2, thereby facilitating the esterification reaction observed in the Fourier transform infrared-attenuated total reflectance spectra. This played an important role in changing the properties of the PLA-based composites. The concave fracture surfaces were consistent with the tensile results, the thermal properties, and the degree of swelling, which suggested that there was a better reaction between stearic acid and RhSiO2. However, the heat deflection temperatures of both the PLA and the CrPLA composites were not significantly affected by blending with either CoSiO2 or RhSiO2. [ABSTRACT FROM AUTHOR]