Ozone Resistance Research Articles

Ageing studies of ethylene propylene diene monomer rubber/styrene butadiene rubber blends: Effects of heat, ozone, gamma radiation, and water

AbstractThe ageing behavior due to the effects of heat, ozone, γ‐ radiation, and water on ethylene propylene diene monomer rubber/styrene butadiene rubber (EPDM/SBR) blends was studied. The tensile strength, crack initiation, ozone ageing, gamma radiation, and water resistance of the blends were measured and used to determine the extent of ageing. Tensile strength of blends of different compositions increased after thermal ageing for 96 h at 100°C probably due to the continued cross‐linking. It has been observed that an increase in EPDM in the blends improves the ozone resistance of the blends. Crack initiation was noted only in blends with lesser amount of EPDM and the cracks in such blends were found deeper, wider and continuous. With 15 kGy irradiation dose, the tensile strength of the blends found to be decreased while it increased with 80 kGy dosage of γ‐radiation. The elongation at break showed a decreasing trend with increased dosage of γ‐radiation. It has also been observed that the EPDM rich blends showed negligible water uptake. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Ozone Resistance of Compounds Based on Halogenated Ethylene–Propylene Rubbers

Ozone Resistance of Compounds Based on Halogenated Ethylene–Propylene Rubbers

Ozone Resistance of Covulcanisates of Rubbers with Different Polarities

Ozone Resistance of Covulcanisates of Rubbers with Different Polarities

Reactive Blending, Reinforcement and Curing of NR/BR/EPDM Compounds for Tire Sidewall Applications

Abstract Tire sidewall compounds are generally formulated using NR and BR to achieve the required dynamical properties. The most widely used antiozonant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), is a staining, toxic and environmentally unfriendly substance. Incorporation of EPDM into NR/BR blends improves ozone resistance, but leads to poor properties because of differences in filler affinity and cure incompatibility of the rubber components. In this work, the cure incompatibility is overcome by utilizing a reactive processing technique, making use of the most commonly used accelerator CBS and sulfur. The entire amount of curatives is first added into the EPDM. After a thermal pretreatment step related to the scorch time of the EPDM, the modified EPDM is mixed with pre-blended NR/BR. The reactive blends show significant improvements of physical properties in comparison with those of conventional straight mixes, due to improvement of the crosslink and carbon black distributions, confirmed by AFM and TEM images. The physical properties of the reactive mixed NR/BR/EPDM blends are equivalent or even superior to regular filled NR/BR blends for tire sidewall applications. The blend with 30 phr of EPDM has excellent ozone resistance while 6PPD can be totally omitted from the formulation.

Ozone resistance of crosslinked blends of butadiene-acrylonitrile and ethylene-propylene-diene elastomers and interphase interaction in these blends

The relation of ozone resistance to the volume and structure of the interphase layer and the amounts of crosslinks in the interlayer was studied for covulcanizates of butadiene-acrylonitrile rubbers of various polarities with ethylene-propylene-diene (EPDM) elastomers that differed in the comonomer composition and stereoregularity of propylene units. It was shown that the ozone resistance is determined by the compatibility of the components, the interlayer volume and density, the amount of crosslinks in the interlayer, and the strength of the EPDM network.

Effect of blend ratio on aging, oil and ozone resistance of silica-filled chloroprene rubber/natural rubber (CR/NR) blends

The effect of blend ratio on properties of chloroprene rubber/natural rubber (CR/NR) blends was investigated. In addition to the mechanical properties, attention was also given to the resistance to thermal aging, oil and ozone of the blends. Silica was selected as a reinforcing filler in this study due to its unique characteristic to interact with CR. The results reveal that, due to the better filler dispersion and the greater crosslink density, the silica-filled CR possesses lower com- pound viscosity and better mechanical properties, compared to the silica-filled NR. The aging properties, oil and ozone resistance of the silica-filled CR are also significantly better than those of the silica-filled NR. The mechanical properties and the resistance to degradation of the silica-filled CR/NR blends are mainly governed by the blend morphology. It is found that good mechanical properties in association with adequately high resistance to degradation from thermal aging and oil are obtained when CR remains the matrix in the blends. Even though the ozone cracks are found in all blends, a thorough look at the results reveals that considerable improvement in ozone resistance is achieved with increasing CR content.

Blending of NR/BR/EPDM by reactive processing for tire sidewall applications. III. Assessment of the blend ozone‐ and fatigue‐resistance in comparison with a conventional NR/BR compound

AbstractThe NR/BR blend compound formulations for tire sidewall applications contain a set of stabilizers added to prevent degradation mainly due to oxygen, ozone, and heat. 6PPD is the most effective and widely used antiozonant in tire compounds, but is a highly staining material causing a surface discoloration of the tire sidewall. Incorporation of 30 phr EPDM into blends of NR/BR improves the ozone resistance to the required level, without the need of 6PPD. The first two parts of this series have described a reactive processing technique applied to enhance the covulcanization and blend homogeneity, together with their characterization. In the present article, the properties of the NR/BR/EPDM blends prepared by both reactive and straight mixing are tested in comparison with those of equivalent conventional NR/BR compounds. The reactive NR/BR/EPDM blend vulcanizates show excellent tensile strength, elongation at break, tear strength, fatigue‐to‐failure, and ozone resistance in both static and dynamic conditions. The properties are equivalent or even superior to those of the conventional NR/BR tire sidewall compounds. The simple straight mixed NR/BR/EPDM blend vulcanizates distinctively possess inferior mechanical properties compared to those of the reactive mix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2555–2563, 2007

Blending of NR/BR/EPDM by reactive processing for tire sidewall applications. I. Preparation, cure characteristics and mechanical properties

AbstractEPDM incorporated into blends of natural rubber/butadiene rubber (NR/BR) improves ozone resistance. In this work, the inferior mechanical properties of NR/BR/EPDM blends generally obtained by conventional straight mixing are overcome by utilizing a reactive processing technique. The entire amount of curatives, based on a commonly employed accelerator N‐cyclohexyl‐2‐benzothiazole sulfenamide (CBS) and sulfur, is first added into the EPDM phase. After a thermal pretreatment step tuned to the scorch time of the EPDM phase, the modified EPDM is mixed with premasticated NR/BR. The reactive blend vulcanizates show a significant improvement in tensile properties: tensile strength and elongation at break, as compared to those prepared by straight mixing, in both gum and carbon black‐filled blends. The increase of tensile properties in gum and filled reactive blend vulcanizates does suggest that the reactive processing technique leads to more homogeneous blends due to, either a better crosslink distribution, or more homogeneous filler distribution, or both. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:2538–2546, 2007

Ozone cracking and flex cracking of crosslinked polymer blend compounds

AbstractOzone cracking and flex cracking of crosslinked elastomer blends of brominated isobutylene/para‐methylstyrene copolymer (BIMSM) and unsaturated elastomers, such as polybutadiene rubber (BR) and natural rubber (NR), are studied. This saturated BIMSM elastomer, which is a terpolymer of isobutylene, para‐bromomethylstyrene, and para‐methylstyrene, functions as the ozone‐inert phase of the blend. Ozone cracking is measured by the failure time of a tapered specimen under a fixed load in a high severity ozone oven, whereas flex cracking is ranked by the De Mattia cut growth. The ozone resistance of BIMSM/BR/NR blends is compared to that of a BR/NR blend (with or without antiozonant) at constant strain energy densities. The effects of the BIMSM content in the blend, the structural variations of BIMSM, and the network chain length between crosslinks on these two failure properties, which are important in crosslinked compounds for applications in tire sidewalls, are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2183–2196, 2007

HXNBR Coating for Improving Aging Resistance of Natural Rubber Products

Abstract HXNBR (Hydrogenated Carboxylated Nitrile Rubber) has very good heat ageing resistance and oil resistance. A novel accelerator system is designed to bring about the vulcanization of HXNBR at room temperature. The room temperature cured samples showed good mechanical properties equivalent to those of high (150 °C) temperature cured samples. Natural rubber vulcanizates are highly prone to oxidative and ozone degradation. The oil resistance of natural rubber vulcanizates is also very low. The oil resistance, ozone and oxidative degradation resistance of natural rubber vulcanizates are considerably improved by placing a thin coating of HXNBR over it.

Mechanical properties and blend compatibility of natural rubber –chlorosulfonated polyethylene blends

AbstractNatural rubber (NR) was blended with chlorosulfonated polyethylene (CSM) with various formulation and blend ratios (NR/CSM: 80/20 –20/80, wt/wt). Rubber blends were prepared by using a two‐roll mill and vulcanized in a compression mold to obtain the 2 mm‐thick sheets. Tensile properties, tear resistance, thermal aging resistance, ozone resistance, and oil resistance were determined according to ASTM. Compatible NR/CSM blends are derived from certain blends containing 20–30% CSM without adding any compatibilizing agent. Tensile and tear strength of NR‐rich blends for certain formulations show positive deviation from the rule of mixture. Thermal aging resistance depends on formulation and blend ratio, while ozone and oil resistance of the blends increase with CSM content. Homogenizing agents used were Stuktol®60NS and Epoxyprene®25. Stuktol®60NS tends to decrease the mechanical properties of the blends and shows no significant effect on blend morphology. Addition of 5–10 phr of epoxidized natural rubber (ENR, Epoxyprene® 25) increases tensile strength, thermal aging resistance, and ozone resistance of the blends. It is found that ENR acts as a compatibilizer of the NR/CSM blends by decreasing both CSM particle size diameter and α transition temperature of CSM. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 127–140, 2006

Study of metal poisoning in natural rubber–based tire‐tread compound

AbstractIn the present study the effect of metal poisoning was studied in a natural rubber (NR)–based tire‐tread compound. The experimental compound contained 1000 ppm copper metal as an additional ingredient. A detailed study was carried out and the results of the experimental compound were compared against a control compound having no metal ion. The effect of metal poisoning was not significant in the case of the green experimental compound, even after prolonged storage of 150 days. However, the cured experimental compound deteriorated substantially after ageing in aerobic‐, anaerobic‐, oil‐, and outdoor‐ageing conditions. The ozone resistance property of the experimental compound also proved to be inferior. The degradation kinetic of metal poisoning was found to be a first‐order reaction and the service life (as expressed by the half‐life period) was drastically reduced for the poisoned compound. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1492–1499, 2005

Constrained-layer Dampers for Attenuation of Structural Vibration

In a constrained-layer damping system, a thin layer of a viscoelastic material is applied over the vibrating substrate. and covered with a stiff constraininglayer of a metal or a fibre-reinforced plastic. Several viscoelastic materials based on elastomeric blends of copoly (acrylonitrilebutadiene) and polyvinyl chloride were developed. These materials were characterised for hardness, tensile properties, ozone resistance, and electrical and dynamic mechanical properties. Two polymer compositions were used to fabricate 1 mm sheets. The sheets were fixed on an aluminium substrate with a rigid epoxy glue. A fibre-reinforced plastic sheet of 300 p was fixed on the viscoelastic layer by a rigid epoxy glue. The experimental setup for the measurement of vibration response has been elaborated. The study was carried out with and without the constrained-layer damping system. The vibration attenuation achieved was to a minimum of 5-7 dB at 200-500 Hz and to a maximum of 9- 16 dB at 3000 - 4000 Hz for the selected constrainedlayer damping system.

合成ゴムの最近の動向 エピクロロヒドリンゴムの最近の動向

Epichlorohydrin rubber has good heat, cold, oil, and ozone resistance. It is utilized for automotives and industrial rubber using its performance.In the automotive field, there are some request, for example, the improvement of durability, functionalize, and restriction of material. Those request come from increased temperature in engine room, automotive emission standard, and recycle etc…On the other hand, epichlorohydrin rubber has unique semi-conductivity. This rubber is used in printer or copy machine.It was written in this report that development for automotive use and these restriction, and development for OA machine use of epichlorohydrin rubber.

Development of Isobutylene Based Rubbers-Butyl Rubbers and Others-

Isobutylene based rubbers have unique property such as impermeability to air and various gases. Main product of isobutylene based rubbers is butyl rubber, which was commercialized about 60 years before and has been used mainly for tire innertubes. Halobutyl rubbers were invented and enabled co-cure with natural rubber. The halobutyl rubbers are used mainly in tire innerliner application. To further meet market/customer requirements to butyl rubbers in various applications, star-branched butyl rubbers were developed mainly to improve processability of butyl rubbers with bimodal molecular weight distribution including star shape molecules as high molecular weight portion. And brominated Isobutylene-co-p-methylstyrene rubbers of which ozone and heat resistance were improved by the saturated backbone and cross-linking chemistry, respectively, were also commercialized. Both star-branched butyl and brominated Isobutylene-co-p-methylstyrene rubbers maintain attributes of butyl rubbers.

ポリマーブレンドの基礎と応用 １．相溶性と応用

Thermodynamic discussion on the miscibility between dissimilar polymers leads to: (i) the contribution of combinatorial entropy of mixing to the miscibility is negligibly small and (ii) the miscibility is mostly caused by the hydrogen bonding-type intermolecular specific interactions and the repulsive intramolecular interactions in random copolymers. By analyzing the fee energy curve, the free energy of mixing as a function of composition, phase diagrams are described in terms of the binodal curve and the spinodal curve. Criterions of polymer-polymer miscibility are deduced in the framework of such thermodynamic discussion.The polymer-polymer miscibility is applied: (i) to improve melt-processability (PPE/PS), (ii) to improve ozone resistance (NBR/PVC), (iii) to reduce optical anisotropy (to provide zero-birefringence plastics), (iv) to improve heat resistance (PEEK/PET), and (v) to make materials flexible (PVC/EVA).

Ozone exposure induces the activation of leaf senescence-related processes and morphological and growth changes in seedlings of Mediterranean tree species

Four Mediterranean tree taxa, Quercus ilex subsp. ilex, Quercus ilex subsp. ballota, Olea europaea cv. vulgaris and Ceratonia siliqua, were exposed to different ozone (O 3) concentrations in open top chambers (OTCs) during 2 years. Three treatments were applied: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air plus 40 ppb v of O 3 (NF+). The photochemical maximal efficiency, Fv/ Fm, decreased in NF+ plants during the second year of exposure, especially during the most stressful Mediterranean seasons (winter and summer). An increase of δ 13C was found in three of the four studied species during the first year of exposure. This finding was only maintained in C. siliqua during the second year. Decreases in the chlorophyll content were detected during the first year of fumigations in all the species studied, but not during the second year. The NF+ treatment induced changes in foliar anatomical characteristics, especially in leaf mass per area (LMA) and spongy parenchyma thickness, which increased in some species. A reduction in N content and an increase in δ 15N were found in all species during the second year when exposed in the NF+ OTCs, suggesting a change in their retranslocation pattern linked to an acceleration of leaf senescence, as also indicated by the above mentioned biochemical and anatomical foliar changes. The two Q. ilex subspecies were the most sensitive species since the changes in N concentration, δ 15N, chlorophyll, leaf area, LMA and biomass occurred at ambient O 3 concentrations. However, C. siliqua was the most responsive species (29% biomass reduction) when exposed to the NF+ treatment, followed by the two Q. ilex subspecies (14–20%) and O. europaea (no significant reduction). Ozone resistance of the latter species was linked to some plant traits such as chlorophyll concentrations, or spongy parenchyma thickness.

Studies on the cure and mechanical properties of blends of natural rubber with dichlorocarbene modified styrene–butadiene rubber and chloroprene rubber

This paper focused on the comparative evaluation of cure characteristics and mechanical properties of blends of natural rubber with dichlorocarbene modified styrene–butadiene rubber and chloroprene rubber with different blend composition. It was found that the Mooney scorch time and cure index shows a negative deviation from the calculated value based on the interpolation between the two component elastomers. However for the blends, modulus and hardness show a positive deviation. The mechanical properties of NR/DCSBR blend are higher than that of NR/CR blends. Flammability, oil and ozone resistance of the blend showed that as the NR content in the blend increases these properties were decreases and also NR/DCSBR blend showed excellent thermal, oil and ozone resistance than that of NR/CR in entire blend ratios. The mechanical properties, modulus and hardness were also investigated after oil immersion. The changes in mechanical properties were correlated with variation in cross-link density estimated from stress–strain and swelling behavior.

New oligomer‐bound antioxidants in natural rubber/polybutadiene rubber and natural rubber/styrene–butadiene rubber blends

AbstractNew paraphenylene diamine antioxidants were prepared. The efficiency and permanence of these oligomer‐bound paraphenylene diamines were compared with those of conventional amine‐type antioxidants in elastomer blends such as natural rubber/styrene–butadiene rubber and natural rubber/polybutadiene rubber. These oligomer‐bound antioxidants showed improved aging resistance and ozone resistance in comparison with the blends containing conventional antioxidants. The liquid oligomer‐bound paraphenylene diamine could replace the plasticizer required for compounding. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 437–443, 2004

오존을 포함한 환경인자가 EPDM고무와 CR고무 블렌드의 물성에 미치는 영향

With the help of mechanical mixing method such as Banbury mixer and open 2 roll mill, ethylene propylene diene terpolymer (EPDM) was blended with the chloroprene rubber (CR) then mechanical properties and ozone resistance test of blends were subsequently investigated. It was noted that the hardness increased with an increasing of CR contents. Generally the hardness was increased with heat aging time most likely due to the post cure. In ozone resistance test of blend, after 8 hours a portion of fine crack is obtained for pure CR. It is confirmed that ozone resistance is greatly improved by addition of 25wt% EPDM to CR.