Thermally induced crosslinking between polyacrylic acid and epoxidized natural rubber. III. Effect of carbon black filler and mixer rotor speed

High-temperature molding of Brabender-mixed blend of polyacrylic acid (PAA) and epoxidized natural rubber (ENR) causes thermally induced crosslinking between PAA and ENR. Studies on Monsanto rheometry of the blend and physical properties, solvent swelling, and dynamic mechanical properties of the molded blend show that both mixer rotor speed and carbon black filler influence the crosslinking between the component polymers. For example, the extent of crosslinking for the 50–50 PAA–ENR blend was found maximum when the component polymers were mixed at 40 rpm, but the same blend filled with 30 phr HAF carbon black filler showed maximum crosslinking when mixing was carried out at 120 rpm. The results have been explained on the basis of formation of network on the filler surface, which in turn depends on two competing factors: increase in bound rubber formation with increase in filler loading at a fixed rotor speed and enhanced degradation of ENR at higher mixer rotor speed at a fixed filler loading. © 1994 John Wiley & Sons, Inc.     

Preparation and characterization of shape memory polymer networks based on carboxylated telechelic poly(ɛ-caprolactone)/epoxidized natural rubber blends

Shape memory polymer networks were prepared from blends of end-carboxylated telechelic poly(?-caprolactone) (XPCL) and epoxidized natural rubber (ENR). The XPCL/ENR blends can form cross linked structure via interchain reaction between the reactive groups of each polymer during molding at high temperature. Degree of crosslinking of the blend network and their thermomechanical properties were characterized by gel content measurement, DSC and DMA. We found that the degree of crosslinking and crystalline melting transition temperatures was dependent upon the blend compositions as well as the molecular weight of the XPCL segment in the blends. The blends showed a good shape memory behavior such as good shape fixity as well as a high final recovery rate when they exhibit crystalline melting transition with a sufficiently high degree of crosslinking. And the response temperature of the recovery was well matched with T_m of the samples.     

Irradiation Crosslinking of PVC/ENR Blend: A Comparative Study with the Respective Homopolymers

Electron beam initiated crosslinking on a 50/50 poly(vinyl chloride)/epoxidized natural rubber blend was studied in the absence and presence of 3 phr trimethylolpropane triacrylate (TMPTA). Comparative studies were made on PVC and ENR homopolymers. The samples were irradiated by using a 3.0 MeV electron beam machine at doses ranging from 20 to 200 kGy in air and room temperature. The changes in tensile strength, gel fraction and tan δ curves of the samples were investigated. The enhancement in tensile strength, gel fraction, glass transition temperature together with a concomitant decline tan δ peak revealed that under the irradiation conditions employed, the PVC/ENR blend crosslinked by electron beam irradiation. Addition of 3 phr TMPTA found to be effective in increasing the degree of crosslinking. Similar observations were also noted for the homopolymers PVC and ENR, implying that both PVC and ENR in the blend undergo crosslinking to a certain extent.     

亚乙基硫脲对PVC和PVC/ENR共混物的交联作用

从交联速率、压缩永久变形、凝胶质量分数、强伸性能和耐热性能等方面考察了亚乙基硫脲（ＥＴＵ）和ＥＴＵ／硫黄对ＰＶＣ及其与环氧化天然橡胶（ＥＮＲ）共混物的交联作用。结果表明,ＥＴＵ和ＥＴＵ／硫黄对ＰＶＣ及其与ＥＮＲ的共混物有明显的交联作用;交联后共混物的物理性能和耐热性能均有较大提高;适当增大ＥＮＲ用量,有利于提高共混物的热变形性能;ＰＶＣ／ＥＮＲ的共混比为７０／３０时,硫黄的最佳用量为１５份,促进剂选择促进剂ＤＭ／ＴＭＴＤ体系为佳。     

Effect of reinforcing carbon black filler on thermally induced crosslinking of polyacrylic acid-epoxidized natural rubber blend

That carbon black filler influences the thermally induced crosslinking between polyacrylic acid (PAA) and epoxidized natural rubber (ENR) is evident from Monsanto rheometric studies, dynamic mechanical analyses, and physical property measurements. Considerable shift in glass transition temperature, as well as broadening of the loss peak due to ENR, along with disappearance of the loss peak due to PAA, indicate that HAF carbon black, at 20 parts per 100 of total polymer, make the immiscible PAA/ENR blend behave as a compatible blend. © 1993 John Wiley & Sons, Inc.     

Effect of trimethylolpropane triacrylate (TMPTA) on the properties of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend

The effect of trimethylolpropane triacrylate (TMPTA) monomer on the tensile properties, dynamic mechanical properties, and morphology of irradiated epoxidized natural rubber (ENR‐50), ethylene‐(vinyl acetate) copolymer (EVA), and an ENR‐50/EVA blend was investigated. The ENR‐50, EVA, and ENR‐50/EVA blend were irradiated by using a 3.0‐MeV electron‐beam apparatus at doses ranging from 20 to 100 kGy. The improvement of tensile properties and morphology with irradiation indicated the advantage of having irradiation‐induced crosslinks in these materials. Observation of the properties studied confirmed that TMPTA was efficient in enhancing the irradiation‐induced crosslinking of ENR‐50, EVA, and the ENR‐50/EVA blend. Addition of TMPTA improved the adhesion between the ENR‐50/EVA blend phases by forcing grafting and crosslinking at a higher irradiation dose (100 kGy). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers.     

Mechanical Properties and Thermooxidative Aging of a Ternary Blend,Pvc/Enr/Nbr,Compared with the Binary Blends of Pvc

In the quest to improve the thermooxidative aging of the poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend, nitrile rubber (NBR) was incorporated into the blend to yield a ternary blend of PVC/ENR/NBR. A Brabender Plasticorder with a mixing attachment was used to perform the melt mixing at 150°C and 50 rpm followed by compression molding. The mechanical properties, dynamic mechanical properties, and thermooxidative aging behavior of the ternary blend were compared with those of the binary blends (i.e., PVC/ENR and PVC/NBR). It was found that the ternary blend exhibits mechanical properties which are superior to those of PVC/ENR. A single glass transition temperature (T _g) obtained from dynamic mechanical analysis coupled with synergism in the modulus and some other mechanical properties indicate that PVC, ENR, and NBR form a single phase (miscible system) in the ternary blend. Di-2-ethyl hexylphthalate (DOP) plasti-cizer improves the aging resistance of the blends generally, whereas the presence of CaCO₃ as a filler only imparts minor influences on the properties and aging resistance of the blends.     

Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate

Electron‐beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glass‐transition temperature (T_g), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron‐beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the T_g with the distance between crosslinks provided further evidence of irradiation‐induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1914–1925, 2001     

Effect of electron‐beam irradiation on poly(vinyl chloride)/epoxidized natural rubber blend: dynamic mechanical analysis

The irradiation‐induced crosslinking in 50/50 poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend was investigated by means of dynamic mechanical analysis. The influence of trimethylolpropane triacrylate on the irradiation‐induced crosslinking of PVC/ENR blends was also studied. The enhancement in storage modulus and T_g with irradiation dose indicated the formation of irradiation‐induced crosslinks. This is further supported by the decrease in tan δ_max and loss modulus peak. The compatibility of the blend was found to be improved upon irradiation. The Fox model was used to provide a further insight into the irradiation‐induced compatibility in the blend. Scanning electron microscopy studies on the cryofracture surface morphology of the blends as well as the homopolymer have been undertaken in order to gain more evidence on the irradiation‐induced crosslinking. © 2001 Society of Chemical Industry     

Self-vulcanizable rubber blend systems based on epoxidized natural rubber and chlorosulfonated polyethylene: Effect of blend composition,epoxy content of epoxidized natural rubber,and reinforcing black filler on physical properties

Mill mixed blend of epoxidized natural rubber and chlorosulfonated polyethylene forms a self-vulcanizable rubber blend during molding at high temperatures in absence of any vulcanizing agent, which is confirmed by FTIR studies. The extent of vulcanization reaction not only depends upon time and temperature of molding but also on the level of epoxidation in ENR and its proportion present in the blend. Physical properties of the blends are comparable to that of conventional rubber vulcanizates. Such blends can be reinforced by carbon black filler.     

Study on the self-crosslinking behavior based on polychloroprene rubber and epoxidized natural rubber

This work has studied the impact of curing temperature and rubber compositions on the self-crosslinking behavior of the polychloroprene rubber (CR) and epoxidized natural rubber (ENR) blend. Variation of the temperature and blending ratios, rheological results have shown a better crosslinking result at 160°C with the optimum CR ratio at 75%. Then, Arrhenius equation was applied to verify the crosslinking kinetic and first-order kinetics has been verified. The chemical reaction routes proposed by differential scanning calorimetry have also been analyzed. Moreover, dynamic mechanical analysis and field emission scanning electron micrographs combined with energy-dispersive X-ray analysis were done to evaluate the phase compatibility. Based on the experimental results, a proposal “cross-promotion” reaction is drawn to conclude the self-crosslinking of CR and ENR. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of blend ratio on Mooney scorch time of rubber blends

The Mooney scorch times of three rubber blends [epoxidized natural rubber (ENR) 50/SMR L, ENR 50/styrene butadiene rubber (SBR), and Standard Malaysian Rubber SMR L/SBR] were studied in the temperature range of 120–160°C using an automatic Mooney viscometer. N-Cyclohexyl-2-benzothiazyl sulfenamide was used as the accelerator, and the rubber formulation was based on the conventional vulcanization system. Results for the blends investigated indicate that a negative deviation of scorch time from the interpolated value was observed, especially for temperatures lower than 130°C. This observation was attributed to the induction effect of the ENR 50 in the ENR 50/SMR L and ENR 50/SBR blends to produce more activated precursors to crosslinks, thus enhancing interphase crosslinking. To a lesser extent, SMR L also exhibited such an induction effect in the SMR L/SBR blend. At 120°C, maximum induction effect occurred at around a 40% blend ratio of ENR 50 and SMR L in the respective blends. For the filled stock at 140°C, carbon black exhibited less effect on the scorch property of the blends compared to silica. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1301–1305, 1998     

Dynamic Mechanical and ESCA Studies of Aluminium-Aluminium Bonding by an Epoxidised Natural Rubber-Polyacrylic Acid Blend

A polyacrylic acid (PAA)-epoxidised natural rubber (ENR) blend becomes crosslinked during high temperature moulding and such a blend was found to be a good adhesive for aluminium (Al)-aluminium (Al) bonding. The joint strength can be improved by the incorporation of silica filler into the adhesive up to a loading of 5 phr. However, higher filler loading causes deterioration of the joint strength. Electron Spectroscopy for Chemical Analysis (ESCA) studies of the peeled and then leached Al surface shows that the ENR phase of the blend is primarily responsible for the adhesion with the Al surface. With the increase in filler loading adhesion with Al increases at the cost of crosslinking between the component polymers. This is substantiated by dynamic mechanical analyses of the blends and joints (that is, Al/blend/Al composites). The changes in dynamic mechanical properties of the blends due to Al adhesion could be correlated with the peel strength of the Al/blend/Al joints.     

Physico-mechanical properties and automotive fuel resistance of EPDM/ENR blends containing hybrid fillers

This research aimed to investigate the effect of blend ratios on cure characteristics, mechanical and dynamic properties, morphology and automotive fuel resistance of ethylene-propylene diene rubber (EPDM) and epoxidized natural rubber (ENR) blends containing carbon black and calcium carbonate hybrid filler. The composition of EPDM/ENR blends varied were 100/0, 70/30, 50/50, 30/70 and 0/100 %wt/wt. All ingredients used for preparing each blended compound, except for the curatives, were mixed in a kneader. Thereafter, the compound was further mixed with curatives on a two-roll mill and then were vulcanized together with shaped by compression molding before determining cure characteristics, mechanical properties, morphology and weight swelling ratio in three automotive fuels; gasohol-91, diesel and engine oils. The results indicated that Mooney viscosity and cure time of EPDM/ENR blends tended to decrease with increasing ENR content, while cure rate index and crosslink density increased. Tensile strength of all EPDM/ENR blends is lower than that of the individual EPDM and ENR. This is attributed to the incompatibility between nonpolar and polar nature of EPDM and ENR, respectively, supporting by the glass transition temperature form dynamic mechanical thermal analysis (DMTA) and scanning electron micrographs (SEM). Owing to the differences in polarity of automotive fuels and rubbers, weight swelling of EPDM/ENR vulcanizates decreased in diesel and engine oils, but increased in gasohol-91 with increasing in ENR content.     

Modification of PVC/ENR blends by electron beam irradiation

The effects of electron irradiation, with doses ranging from 20 to 100 kGy on the physical properties of poly(vinyl chloride)/epoxidised natural rubber blends (PVC/ENR50 blends) were investigated. The enhancement in tensile strength, elongation at break, hardness, and aging properties of the blends have confirmed the positive effect of irradiation on the blends. Crosslinking of the ENR50 phase proved to play a major role in the improvement of mechanical properties of blends. The results also revealed that at any blend composition the enhancement in properties depends on the irradiation dose which controls the degree of radiation-induced crosslinking. The single glass transition temperature obtained confirms that the blends remain miscible upon irradiation.     

环氧化天然橡胶改性PA6/EPDM共混物

研究了环氧化天然橡胶（ENR）对聚酰胺6（PA6）／EPDM共混物的力学性能、热性能和结晶行为的影响。结果表明,ENR可以显著提高共混物的韧性,ENR含量为5％时共混物的制品冲击强度达14kJ/m^2,同时不会降低共混物的拉伸强度和维卡软化。DCS分析证明,共混物的相容性有所改善,共混物相界面间可能有PA6／ENR接枝共聚物产生。     

Self-crosslinkable plastic-rubber blend system based on poly (vinyl chloride) and acrylonitrile-co-butadiene rubber

That the melt-mixed blend of poly (vinyl chloride) and acrylonitrile-co-butadiene rubber becomes crosslinked during high-temperature molding is evident from Monsanto rheometric, solvent swelling, and infrared spectroscopic studies. Dynamic mechanical analysis shows that such a self-crosslinkable plastic-rubber blend is miscible in different blend ratios. The degree of crosslinking depends on the blend ratios and the molding conditions. The cross-linking reaction involves the allylic chlorine sites in poly (vinyl chloride) and the ? C?N group in the nitrile rubber. © 1993 John Wiley & Sons, Inc.     

Electron Beam Irradiation of EVA/ENR Blend

The effect of irradiation on a 50/50 ethylene vinyl acetate/epoxidized natural rubber blend was studied. The 50/50 ethylene vinyl acetate/epoxidized natural rubber blend was prepared by mixing in a Brabender Plasticoder at 120°C. The blend was then irradiated by using a 3.0 MeV electron beam machine at doses ranging from 20 to 100 kGy in air and room temperature. The dynamic mechanical properties, tensile properties, hardness, and gel fractions of the blends were measured. It was found that the tensile strength, modulus, and hardness of the blend increased with irradiation with a concomitant decline in elongation at break. Results on the gel fraction revealed that under the irradiation conditions employed, the EVA/ENR blend crosslinked by electron beam irradiation. The addition of TMPTA and Surlyn ionomer was found to be effective in increasing the degree of crosslinking.     

Irradiation crosslinking of PVC–ENR blend Effect of efficient radical scavenger

Abstract

The irradiation induced crosslinking of 50:50 poly (vinyl chloride)–epoxidised natural rubber (PVC–ENR) blend was studied in the presence of 0–1·5 pphr antioxidant Irganox 1010. The samples were irradiated using a 3·0 MeV electron beam machine at doses ranging from 20 to 200 kGy in air and room temperature. The gel fraction, tensile strength T _s, modulus at 100% elongation M ₁₀₀, elongation at break E _b, hardness, and resilience were used to follow the irradiation induced crosslinking of the blend. The decline in gel fraction, T _s, M ₁₀₀, hardness, and resilience and the concurrent increase in E _b with increasing antioxidant indicated the inhibition of irradiation induced crosslinking by the antioxidant used. The improvement in aging properties of the blend with the addition of the antioxidant is also reported. It was evident from FTIR that Irganox 1010 is involved in the stabilisation of the blend against irradiation induced degradation.     

Melt flow behavior of blends from poly(vinyl chloride) and epoxidized natural rubber

Blends from poly(vinyl chloride) (PVC) and epoxidized natural rubber (ENR) were prepared in a Brabender plasticorder by the melt blending technique. The melt flow behavior of these blends with respect to blend ratio and temperature has been examined using a melt flow indexer and capillary rheometer. ENR decreases the Brabender torque, increases the melt flow index (MFI), and decreases the melt viscosity of PVC in the blends. Arrhenius plots were used to study the effect of temperature on melt flow index (MFI) and viscosity. Moreover, the flow behavior index (n′) obtained from capillary rheometer data was found to be dependent on temperature and blend ratio.