Effect Of Dicumyl Peroxide Research Articles

Ultra-Tough Polylactide/Bromobutyl Rubber-Based Ionomer Blends via Reactive Blending Strategy.

A series of ultra-toughened sustainable blends were prepared from poly(lactic acid) (PLA) and bromobutyl rubber-based ionomers (i-BIIRs) via reactive blending, in which dicumyl peroxide (DCP) and Joncryl®ADR-4440 (ADR) were used as reactive blending additives. The miscibility, phase morphology and mechanical property of the PLA/i-BIIRs blends were thoroughly investigated through DMA, SEM, tensile and impact tests. The influence of different ionic groups and the effects of DCP and ADR on the compatibility between the phases, phase structure and mechanical properties were analyzed. The introduction of the imidazolium-based ionic groups and the reactive agents enable the i-BIIRs play multiple roles as effective compatibilizers and toughening agents, leading to improved interfacial compatibility and high toughness of the blends. The mechanical properties test showed that the PLA/i-BIIRs blends exhibit excellent toughness: impact strength and the elongation at break of AR-OH(30)+AD reached 95 kJ/m2 and 286%, respectively. The impact fracture surface showed the large-scale plastic deformation of the PLA matrix in the blends, resulting in greatly absorbing the impact energy. The results proved that simultaneously applying reactive blend and multiple intermolecular interactions methods is an effective toughening strategy for toughening modification of the PLA blends.

Effect of Dicumyl Peroxide on Changes in the Molecular Structure of Asphaltenes in the Course of Cracking of High-Sulfur Tars

Effect of Dicumyl Peroxide on Changes in the Molecular Structure of Asphaltenes in the Course of Cracking of High-Sulfur Tars

Effects of dicumyl peroxide on cross‐linking pure poly(butylene succinate) foaming materials for high expansion and high mechanical strength

AbstractThis paper fabricated the cross‐linking poly(butylene succinate) foaming materials with high expansion ratio, high mechanical strength, and high degradation rate though cross‐linking and molding compression methods. With dicumyl peroxide content increasing, complex viscosity, and storage modulus appear to increase tendency. The properties of cell size, distribution, mechanical properties, and thermal conductivity all appear the first increasing and then decreasing trend with dicumyl peroxide content increasing. When dicumyl peroxide concentration is 6 wt% and azodicarbonamide concentration is 1 wt%, pure cross‐linking poly(butylene succinate) foaming material's expansion ratio and compression strength could reach 7.03 and 5.61 MPa, respectively. In addition, this pure cross‐linking poly(butylene succinate) foaming material has high degradability, and the degradation ratio could get 80% in alkaline aqueous solution.

Effect of dicumyl peroxide on biodegradable poly(lactic acid)/functionalized gum arabic based films

AbstractBlending 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.

Synergistic toughening of poly(lactic acid)/poly(ethylene vinyl acetate) (PLA/EVA) by dynamic vulcanization and presence of hydrophobic nanoparticles

AbstractThe 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.

Microstructure and mechanical properties of 3D Cf/SiBCN composites fabricated by polymer infiltration and pyrolysis

In this work, three-dimensional (3D) Cf/SiBCN composites were fabricated by polymer infiltration and pyrolysis (PIP) with poly(methylvinyl)borosilazane as SiBCN precursor. The 3D microstructure evolution process of the composites was investigated by an advanced X-ray computed tomography (XCT). The effect of dicumyl peroxide (DCP) initiator addition on the crosslinking process, microstructure evolution, and mechanical properties of the composites were uncovered. With the addition of a DCP initiator, the liquid precursor can cross-linking to solid-state at 120 °C. Moreover, DCP addition decreases the release of small molecule gas during pyrolysis, leading to an improved ceramic yield 4.67 times higher than that without DCP addition. After 7 PIP cycles, density and open porosity of the final Cf/SiBCN composite with DCP addition are 1.73 g·cm−3 and ∼10%, respectively, which are 143.0% higher and 30.3% lower compared with the composites without DCP addition. As a result, the flexural strength and elastic modulus of Cf/SiBCN composites with DCP addition (371 MPa and 31 GPa) are 1.74 and 1.60 times higher than that without DCP addition (213 MPa and 19.4 GPa), respectively.

Adhesion between ethylene‐propylene‐diene monomer and thermoplastics in two‐component injection molding: Effect of dicumylperoxide as curing agent

AbstractStrong adhesion at the interface is an important aspect in two‐component (2K) injection molding. It was therefore investigated whether dicumylperoxide (DCP) as curing agent in ethylene‐propylene‐diene monomer (EPDM) could stimulate interdiffusion and/or induce chemical bonding with thermoplastics. EPDM mixtures containing DCP concentrations between 2 to 8 parts per hundred rubber (phr) were combined with polar and non‐polar thermoplastics. Changes in EPDM physico‐mechanical bulk properties were analyzed, and the adhesion was evaluated by high temperature contact angle measurements and tensile testing. Results showed that DCP concentration did not influence EPDM‐thermoplastic compatibility. However, EPDM adhesion with polyethylene (PE) did improve when using up to 6 phr DCP (57% adhesion) as crosslinking is promoted. While with polypropylene (PP), adhesion linearly decreased (from 55% to 35% adhesion) with higher DCP concentrations due to prevailing scission reactions. Adhesion through chemical bonding with acrylonitrile‐butadiene‐styrene (ABS) caused better adhesion at 4 phr (43% adhesion) compared to polycarbonate (PC) at 4 phr (13% adhesion) where only limited interdiffusion occurs. Thus, selecting the optimal DCP concentration is highly important to boost adhesion between EPDM and thermoplastics. Furthermore, at these optimal DCP concentrations, physico‐mechanical properties require consideration as these properties were significantly affected.

IMPROVEMENTS IN THE SYNTHESIS AND CHARACTERIZATION OF GLYCIDYL METHACRYLATE–GRAFTED EPDM THROUGH MELT FREE-RADICAL PROCESS

ABSTRACT Melt free-radical grafting reactions between EPDM and glycidyl methacrylate (GMA) were investigated in the presence or absence of styrene (St) comonomer in a batch mixer (170 °C, 60 rpm). The effects of dicumyl peroxide (DCP) initiator, GMA, and St concentrations were studied on the grafted EPDM characteristics. Torque–time profiles detected the grafting process by a melt viscosity rise. Titration results indicated an increase in the graft degree (GD) and gel content (GC) values with increasing of the DCP concentration. Introduction of St led to a 132% increase in GD and a 39% decrease in GC by preventing macroradicals from crosslinking side-reaction. Glass-transition temperatures of all samples increased compared with the pure EPDM due to the increase in GC. The increase was greater in the samples containing comonomer because of the stronger intermolecular interactions. Fourier-transform infrared spectroscopy spectra and contact-angle measurements confirmed that GMA was grafted onto EPDM. A calibration curve was developed as a criterion to predict the GD in melt free-radical process.

Effects of dicumyl peroxide on cell formation of biopolymer blend-activated carbon composite foams

Immiscible biopolymer blends of polylactic acid (PLA) and polybutylene succinate (PBS) with a weight ratio of 80/20 were compatibilized by different concentrations (0, 0.1, 0.3 and 0.5 parts per hundred resin (phr)) of dicumyl peroxide (DCP) in the presence of 3 phr of activated carbon (AC). Influences of DCP on the melt rheology at foaming temperature, cell formation and morphology and foam properties of PLA-PBS-AC composites using 5 phr of azodicarbonamide (ADC) as a blowing agent were reported. It was found that the melt viscosity, relating to the melt flow index (MFI) of PLA-PBS-AC composite foams increased with increasing DCP loadings due to more compatibility between PLA and PBS. Closed cells with thick cell walls were obtained with the addition of DCP. Also, the cell size and cell density tended to decrease by DCP adding since lower cell expansion and coalescence occurred at higher polymer surface tension. The crystallinity (Xc) and thermal properties of PLA and PBS in composite foams were almost unchanged when DCP was filled in the system. The PLA-PBS-AC composite foam having 0.3 phr of DCP provided the lowest foam density (pf) and the highest void fraction (Vf) of 0.5766 g cm3 and 54% respectively.

Maleic Anhydride-Grafted Isotactic Polybutene-1 and Modified Polyamide 6.

Maleic anhydride (MAH)–divinyl benzene (DVB) multi-monomer melt-grafting onto isotactic polybutene-1 (iPB-1) was carried out in a torque rheometer. The effects of dicumyl peroxide (DCP), MAH, and DVB concentrations, and temperature, on the reaction, were investigated. The optimized conditions were 170 °C, DVB/MAH = 4:6 (mass ratio). DVB as a comonomer enhanced the grafting degree (Gd) and grafting efficiency (Ge) of iPB-g-MAH better than styrene. The initiator DCP had little effect on Gd as its concentration over 0.2 phr, but the grafts’ melt flow rate (MFR) increased significantly, and relative molecular weight decreased remarkably with increased DCP concentration. With increasing Gd, the contact angle of grafts with water decreased, and there was a larger crystallization rate. The study of iPB-1 and iPB-g-MAH (Gd = 1.5%)-modified polyamide 6 (PA6) showed that iPB-g-MAH had an obviously toughening effect on PA6. With increasing iPB-g-MAH concentration, the blends of impact strength and elongation at break increased obviously, tensile strength decreased slightly, and MFR decreased prominently, which greatly slowed the processing degradation of PA6. The properties of iPB-1/PA6 blends deteriorated. Both DSC curves and SEM micrographs confirmed that PA6/iPB-g-MAH blends had much better compatibility than PA6/iPB. The reason was that the anhydride group in iPB-g-MAH reacted with amide group in PA6 to improve the compatibility between two phases, and iPB-g-MAH is an excellent modifier for PA6.

Effects of DCP as a free radical producer and HPQM as a biocide on the mechanical properties and antibacterial performance of in situ compatibilized PBS/PLA blends

In situ compatibilized polybutylene succinate/polylactic acid (PBS/PLA) reactive blends were prepared by adding dicumyl peroxide (DCP) as a radical initiator at contents ranging from 0 to 0.5 pph via a melt blending process. HPQM (2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate) was used as an antibacterial agent at varying dosages from 0 to 5000 ppm. The mechanical properties, physical properties and antibacterial performance against Escherichia coli of PBS/PLA blends were investigated. The results showed that the toughness of PLA increased with increasing PBS content, while the fracture behavior of PLA appeared to change from brittle to ductile. The addition of DCP was found to notably increase the elongation at break and tensile toughness of materials at the recommended loading of 0.2 pph; this optimal DCP loading corresponded to increases in the storage modulus and complex viscosity of PBS/PLA blends. DCP and HPQM addition did not affect the surface color of PBS/PLA blends. According to the antibacterial performance of HPQM against E. coli, the optimal dosages of HPQM loaded into PBS/PLA blends of 20/80 and 40/60 wt% with 0.2 pph of DCP were 2000 and 1500 ppm, respectively.

Improvements in morphology, mechanical and thermal properties of films produced by reactive blending of poly(lactic acid)/natural rubber latex with dicumyl peroxide

The effect of dicumyl peroxide (DCP) as a free-radical cross-linking agent on the morphology, thermal and mechanical properties, and gas permeation of blown films prepared by reactive blending of poly(lactic acid) (PLA) and natural rubber latex was investigated. In comparison to the blown films without DCP, SEM micrographs revealed that the amount of debonded rubber domains from the cryofractured surface reduced considerably. This was when DCP at 0.003 phr was incorporated and the free radicals from thermally decomposed DCP reacted with PLA and NR chains, generating PLA–NR copolymers and cross-linked NR as confirmed by FTIR spectra. These PLA–NR copolymers acted as compatibilizers, which increased the strength at the PLA/NR interfaces, leading to the improvement in tensile strength, elongation at break, tensile toughness, impact strength, and tear strength. Although DCP did not influence the cold crystallization of PLA, TGA thermograms showed that thermal stability slightly increased owing to the enhanced interfacial adhesion. However, the addition of DCP at 0.005 and 0.010 phr resulted in a high content of cross-linked NR gel, by consuming the free radicals instead in copolymer formation. Therefore, the compatibilization efficiency was significantly reduced and the mechanical properties of reactive PLA/NR blown films finally dropped. Also, this poor interfacial adhesion facilitated the microvoid formation at the polymer–rubber interface as a result of mechanical stretching upon the film blowing process, increasing the permeation of water vapor and oxygen molecules. According to our study, it can be summarized that to optimize the morphology, mechanical properties, and gas permeation property of the free radical-assisted reactive blends, it is of great concern to carefully balance reactive compatibilizer formation and gel formation by adjusting the DCP content.

THERMAL EVALUATION OF CURING OF SBR BASED ADHESIVES USING DICUMYL PEROXIDE

Curing is an important process in adhesive formulation, but scant reports on the study of the kinetics of curing in adhesive are currently available, particularly for formulations including styrene-butadiene copolymers. The focus of the present work was to thermodynamically quantify the curing reaction in pressure-sensitive adhesives (PSA) obtained from styrene-butadiene copolymers, the effect of dicumyl peroxide (DCP) ratio, which acts as a crosslinking agent, and also evaluate the effect of two reactive adhesive resins, sylvalite and piccolyte. Kinetic parameters were determined by differential scanning calorimetry (DSC) in an isothermic and dynamic mode, gel content was determined as was swelling degree, given these characteristics can be associated with the curing reaction. The kinetic study showed the curing reaction was first order, according to the Ozawa and Kissinger equation. Resins have affinity to BR segment, while in the case of sylvalite and piccolyte to the PS segment, varying behavior with dicumyl peroxide in the adhesive mixture. Lower swelling values were associated with an increase in crosslinking, indicative a curing reaction took place, and the gel content test was used to corroborate the results.

Properties and curing behavior of reactive blended allyl novolak with bismaleimide using dicumyl peroxide as a novel curing agent

ABSTRACTFor reducing the cure temperature and improving the thermal stability and mechanical properties, a thermosetting resin system composed of novolak and bismaleimide (BMI) was developed by reactive blending and using dicumyl peroxide (DCP) as a novel curing agent. Novolak was allylated and reacted with BMI to produce bismaleimide allylated novolak (BAN), and the effect of DCP on flexural, impact and heat distortion temperature of cured resin were investigated. On the basis of improved mechanical and thermal properties at 0.5% DCP contents, the curing behavior of DCP/BAN resin system was evaluated by DSC analysis. Ene, Diels‐Alder, homo‐polymerization and alternating copolymerization which occurred in DCP/BAN resin system were further verified using FTIR at sequential cure conditions from 140 to 200°C. Kissinger and Ozawa‐Flynn‐wall methods were used to optimize the process and curing reactions of DCP/BAN resin system. The results showed that the addition of 0.5% DCP in BAN reduced the curing temperature and time of the modified resin. For evaluating process ability of the modified system, composite samples using polyvinyl acetyl fiber were molded and tested for flexural properties. The resulting samples showed better flexural properties when compared with the composite made with neat BAN. The modified 0.5% DCP/BAN resin system with good mechanical properties and manufacturability can be used for making bulk molding compounds and fiber reinforced composites required in various commercial and aerospace applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41829.

Mechanical Properties and Morphology of Polypropylene/Polypropylene-g-Maleic Anhydride/Long Glass Fiber Composites

Long glass fiber (LGF)-reinforced polypropylene (PP) was prepared using a self-designed impregnation device. The effect of dicumyl peroxide (DCP) and maleic anhydride (MA) content on the compatibilizer, PP grafted with maleic anhydride (PP-g-MA), was investigated by means of scanning electron microscopy (SEM) and mechanical properties. The experimental results demonstrated that the increase of DCP and MA could effectively improve the interfacial interaction between PP and GF. Good interfacial adhesion between PP and GF in PP/ PP-g-MA /LGF composites was observed from SEM studies for the higher contents of MA. The best mechanical properties of PP/ PP-g-MA /LGF(30%) composites were obtained when the content of DCP and MA were 0.4 and 0.8 wt%, respectively. The storage modulus of the PP/PP-g-MA/LGF composites increased and then decreased with the content of MA. When the content of MA was 0.8 wt%, tan δ had the lowest value, indicating that the corresponding composites had the best compatibility.

Effect of dicumyl peroxide and phenolic resin as a mixed curing system on the mechanical properties and morphology of TPVs based on HDPE/ground tire rubber

Thermoplastic vulcanizates (TPVs) are a special group of thermoplastic elastomer with the characteristic that consists of rubber elasticity and the processability of thermoplastic polymers. TPVs based on high density polyethylene (HDPE)/ground tire rubber (GTR) with phenolic resin (HY‐2045) and dicumyl peroxide (DCP) as vulcanizing agents are prepared through dynamic vulcanization in this article. The blends consisting of 40/60 HDPE/GTR are melt‐mixed in an internal mixer and then pressed with a compression molding machine. The aim of this experiment is to study the influence of a compound curing agent system on the mechanical properties of the HDPE/GTR composites. The results indicate that the mechanical properties of the HDPE/GTR blends are improved significantly by adding 4 phr HY‐2045 and 0.3 phr DCP than those of TPVs without any vulcanizing agents after dynamic vulcanization. The X‐ray photoelectron spectroscopy study and the FTIR‐ATR analysis confirmed that the crosslinking phenomenon occurred in the preparation of TPVs; and the gel fraction analysis indicates that the GTR components and the HDPE components of the HDPE/GTR blends are all moderately crosslinked. In addition, the morphology of the HDPE/GTR blends has been investigated by scanning electron microscopy. POLYM. COMPOS., 36:1907–1916, 2015. © 2014 Society of Plastics Engineers

Preparation and Mechanical Properties of the Environmentally Friendly Wood-Plastic Composites

Good bonding at the interface between HDPE (High density polyethylene) and wood flour was achieved by adding MA (Maleic anhydride) as surface-reactive additive and WD-50 (3-aminopropyltriethoxysilane) as coupling agent products. HDPE-g-MA was prepared by melt grafting polymerization in the presence of DCP (Dicumyl peroxide) using a Hakke Rheocord. The FTIR spectra conformed that MA was successfully grafted onto HDPE and the effects of DCP and MA contents on grafting reaction were also studied. The effects of silane coupling agent (WD-50), wood flour and HDPE-g-MA contents on the mechanical properties of the HDPE-based wood-plastic composites were investigated by electronic tensile tester and impact test enginery. The results indicated that WD-50 (with the content of 2 wt%) and HDPE-g-MA (with the content of 10 wt%) effectively improved mechanical properties of the composite materials.

The Effect of PP and Peroxide on the Properties and Morphology of HDPE and HDPE/PP Blends

ABSTRACTPeroxide cross‐linked high‐density polyethylene (HDPE) and blends of HDPE and polypropylene (PP) were prepared by reactive extrusion. The effect of dicumyl peroxide (DCP) and PP on the properties and morphology of HDPE and blends was studied. The addition of DCP decreased the melt flow rate (MFR) and increased the HAAKE torque and impact strength in both systems. The elongation at break was increased at low DCP concentration (0–0.1 wt%) and then decreased at high DCP concentration. The addition of PP slightly decreased the MFR and mechanical properties of peroxide cross‐linked HDPE. With the addition of DCP, the molecular weight was increased and the molecular weight distribution was broadened in both systems. Scanning electron micrographs of the fracture surfaces indicate that HDPE/PP blends are indeed a two‐phase system. With the addition of DCP, the compatibility of the two phases was improved, resulting in an increase in the impact strength. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 2013, 32, 21326; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21326

Study on the Effect of Dicumyl Peroxide on Structure and Properties of Poly(Lactic Acid)/Natural Rubber Blend

In attempt to enhance the compatibility of NR in PLA matrix, and furthermore to enhance mechanical properties of PLA, PLA/NR blends with strong interaction were prepared in Haake internal mixer, using dicumyl peroxide (DCP) as cross-linker. The effects of dicumyl peroxide on morphology, thermal properties, mechanical properties and rheological properties of PLA and PLA/NR blends were studied. The results indicated that dicumyl peroxide could increase the compatibility of poly(lactic acid) and natural rubber. With small amount of dicumyl peroxide, the effect on NR toughening PLA was enhanced and the tensile toughness of PLA/NR blends was improved. When the DCP content was up to 0.2 wt%, the PLA/NR blend reached the maximum elongation at break (26.21 %) which was 2.5 times of that of neat PLA (the elongation at break of neat PLA was 10.7 %). Meanwhile, with introducing 2 wt% DCP into PLA/NR blend, the maximum Charpy impact strength (7.36 kJ/m2) could be achieved which was 1.8 times of that of neat PLA (4.18 kJ/m2). Moreover, adding adequate amount of DCP could improve the processing properties of blends: the viscosity of PLA/NR blend decreased significantly and the lowest viscosity of the blends could be achieved when the DCP content was 0.5 wt%.

Effects of maleated-PLA compatibilizer on the properties of poly(lactic acid)/halloysite clay composites

A series of maleic anhydride grafted poly(lactic acid) (PLA-g-MAH) was prepared by mixing PLA, dicumyl peroxide (DCP) and maleic anhydride (MAH). Effects of DCP and MAH concentration on the grafting percentage were determined. PLA composites were prepared via melt mixing with halloysite clay (HNC; 3 wt%) and various amount of PLA-g-MAH (4–10 phr) using internal mixer followed by compression molding. Properties of the PLA composites were characterized using three-point bending flexural tests, scanning electron microscopy and differential scanning calorimetry. It was found that the grafting percentage of PLA-g-MAH was influenced by both DCP and MAH concentrations; however, DCP showed more profound effect. By the addition of PLA-g-MAH, the adhesion between PLA and HNC improved, which can be manifested by the enhancement in flexural properties. Degree of crystallinity of PLA/HNC increased significantly by the addition of PLA-g-MAH.