Composite materials based on modified butadiene-styrene rubber

Effect of fabrication procedure of rubber stocks on the strength and fatigue performance of composite materials based on modified butadiene-styrene rubber was examined.     

The thermal properties and the flammability of pigmented elastomeric materials

This paper presents thermal properties of organic pigments such as zinc phthalocyanine and chloroaluminum phthalocyanine that were synthesized according to the literature data. These pigments were characterized by means of elementary analysis and measurements of particle size. They were then incorporated into butadiene-styrene rubber and butadiene-acrylonitrile rubber. The elastomeric mixtures were cross-linked by two methods: using organic peroxide or sulfur. The effect of phthalocyanines on the thermal properties, flammability, and fire hazard of the pigmented polymeric materials obtained as well as on their mechanical properties and cross-linking degree was studied. It has been shown that the phthalocyanine pigments not only impart appropriate esthetic values to the final goods but also increase their thermal stability and considerably reduce the flammability and fire hazard of elastomers and even make possible materials that are self-extinguishing under air atmosphere. These pigments also have a beneficial influence on the degree of cross-linking of the elastomers investigated and their mechanical properties.     

Recovery of Butadiene-Styrene Rubber from Latex at Low Temperature with Various Coagulants

The influence of the charge of a metal cation and the nature of a coagulant on the recovery of butadiene-styrene rubber and properties of rubber stocks and vulcanizates was examined.     

Coagulation of Latex in the Presence of Viscose Fiber and Properties of the Resulting Rubbers,Rubber Stocks,and Vulcanizates

The effect of addition of viscose fiber on the recovery of butadiene-styrene rubber from a latex and on the properties of the commercial rubber and vulcanizates based on it was examined.     

A review of candidate fire retardants for polyisoprene

Polyisoprene elastomer, as natural rubber (NR) or manufactured synthetically (IR), is used in rubber compounds for applications such as tyres, dampers and suspension elements. NR/IR compounds without fire retardants have a low resistance to burning, and emit large quantities of dense smoke. This is because polyisoprene readily decomposes upon heating, by random chain scission, vaporising into a mixture of small aromatic chemical species, which ignite readily and form smoke particles with negligible char residue formation. The effects of commonly used additives on the thermal decomposition and burning of polyisoprene are reviewed; whilst cross-linking agents have significant effects on physical and ageing properties, they have little effect on thermal decomposition and burning. Fillers such as carbon black and silicas reduce the fuel content by dilution of the polymer and the formation of a stabilising residue.Potential approaches for fire retarding IR are reviewed, identifying two main approaches; halogenated additives, or high loadings of aluminium hydroxide (ATH), neither of which are satisfactory. Other potential approaches are identified, including the use of phosphorus and nitrogen based additives as intumescent char formers, and with zeolites as char catalysts. Alternative inorganic fire retardants to ATH are identified for use, and zinc hydroxystannate and zinc borate are considered as synergists with ATH. Expandable graphite (EG) is identified for use in other elastomers and has potential for polyisoprene. Nano-scale fire retardants such as montmorillonite clay and multi-walled carbon nanotubes are reported typically as a secondary additive to hydrated fillers, but have yet to make a successful transition to industrial processing.     

Effect of butadiene/styrene ratio,block structure and carbon nanotube content on the mechanical and electrical properties of thermoplastic elastomers after UV ageing

Thermoplastic elastomers based on a triblock copolymer styrene-butadiene-styrene (SBS) with different butadiene/styrene ratios, block structure and carbon nanotube (CNT) content were submitted to accelerated weathering in a Xenontest, in order to evaluate their stability to UV ageing. It was concluded that ageing mainly depends on butadiene/styrene ratio and block structure, with radial block structures exhibiting faster ageing than linear block structures. Moreover, the presence of carbon nanotubes in the SBS copolymer slows down the ageing of the copolymer. The evaluation of the influence of ageing on the mechanical and electrical properties demonstrates that the mechanical degradation is higher for the C401 sample, which is the SBS sample with the largest butadiene content and a radial block structure. On the other hand, a copolymer derivative from SBS, the styrene-ethylene/butadiene-styrene (SEBS) sample, retains a maximum deformation of ∼1000% after 80 h of accelerated ageing. The hydrophobicity of the samples decreases with increasing ageing time, the effect being larger for the samples with higher butadiene content. It is also verified that cytotoxicity increases with increasing UV ageing, with the exception of SEBS, which remains non-cytotoxic up to 80 h of accelerated ageing time, demonstrating its potential for applications involving exposure to the environment.     

Degradation Treatment of Butadiene-Styrene Copolymer Wastes

Degradation of butadiene-styrene rubber production wastes, coagulums, using a catalytic system based on hydroperoxide, variable-valence metal salt, and alcohol was studied.     

Effect of CTBN rubber inclusions on the curing kinetic of DGEBA-DGEBF epoxy resin

The curing kinetics of an epoxy resin matrix, based on diglycil ether of bisphenol A and F (DGEBA-DGEBF), associated with an anhydride hardener, at different carboxyl-terminated copolymer of butadiene and acrylonitrile liquid rubber (CTBN) concentration (0-10 phr) are studied using a differential scanning calorimetry (DSC) and a stress-controlled rheometer in isothermal and dynamic conditions. The aim of this work is to correlate the presence of the rubber phase with the transition phenomena that occur during the curing process. The CTBN rubber induces a catalytic effect on the polymerization of the pure resin clearly observed by a significant enhancement of the curing rate. Calorimetric and rheological analysis also evidences that gelation and vitrification times take place not punctually but in a wide range of time. Rheological data show that the presence of rubbery phase induces a higher rate of gel formation during the early stages of the reactions, confirming the calorimetric results. Finally the results are compared with theoretical models evidencing a good fitting between experimental and predictive data.     

Fire protection of polypropylene and polycarbonate by intumescent coatings

An innovative way to improve fire‐retardant properties of different polymers by applying intumescent coatings on their surface has been studied. Two polymers have been investigated: polypropylene and polycarbonate. The surfaces were first subjected to a flaming treatment in order to clean them and to increase their wettability and thus improve the adhesion of the coatings. Two different formulations were then applied: a transparent intumescent varnish, based on an acrylic resin, and an intumescent coating based on polyvinylacetate resin. Different parameters have been obtained using several fire tests. The cone calorimeter, the limiting oxygen index and UL94 tests have been carried out to evaluate the fire‐retardant properties obtained for both the intumescent coating and the intumescent varnish. Results clearly evidence an outstanding improvement of the fire‐retardant properties using intumescent coatings without any incorporation of flame retardants in the bulk. Copyright © 2010 John Wiley & Sons, Ltd.     

不饱和聚酯改性研究新进展

综述了不饱和聚酯改性的研究进展。介绍了不饱和聚酯增韧的方法,如液体橡胶、弹性体共混增韧、化学结构改性、纳米复合材料。不饱和聚酯收缩率控制研究,包括聚醋酸乙烯酯、聚苯乙烯、嵌段共聚和无机填料等低收缩添加剂的影响,及新型低收缩不饱和聚酯的合成。讨论了含磷阻燃剂和无卤阻燃剂对不饱和聚酯的影响。     

The Effect of Hollow Corundum Microspheres on the Properties of Materials Based on Carbon-Chain Rubbers

The effect of hollow corundum microspheres on the properties of a rubber mixture based on a combination of carbon-chain rubbers was studied. Owing to the formation of a cross-linked structure of microspheres with a rubber matrix and its additional structuring with Hexol KhPI adhesion modifier, it was shown that it is possible to increase the physicomechanical characteristics and the heat and fire resistance of rubber by establishing the optimal microsphere content in it.     

Mathematical modeling of butadiene rubber synthesis process on neodymium-containing catalyst system

The synthesis of butadiene rubber mediated by a lanthanide catalyst system based on neodymium(III) chloride in a batch reactor was mathematically modeled. The mechanism of the process was identified and the rate constants of various reaction steps were determined. It was found that chain transfer reactions with different rate constants have an effect on the molecular-mass characteristics of butadiene rubber.     

Modification estimate of kaolin,chalk, and precipitated calcium carbonate as plastomer and elastomer fillers

Investigation into possible modifications of surfaces of white fillers such as Kornica chalk, precipitated calcium carbonate and KOG Kaolin. The surfaces of these fillers were modified with a variety of proadhesive compounds in different amounts. Optimum proadhesive compound was determined for each kind of filler. The modified fillers were tested in rubber mixtures based on butadiene-styrene rubber and in polyurethanes.     

Modification of oxidized bitumen with styrene-butadiene-styrene copolymers of various structures

Mechanical and structural-rheological properties of oxidized bitumen modified with styrene butadiene-styrene copolymers side vinyl groups in their butadiene fragment were studied. A comparative analysis of the modified and unmodified bitumen composites was performed.     

The influence of stabilizers on the properties of silicone rubber

The influence of various stabilizers on the properties of rubber based on silicone rubber SKTV is studied. It is established that the use of the Ca/Zn stabilizer in the resin composition makes it possible to increase thermal resistance and physico-mechanical characteristics of the rubber used to make sealing elements in the automotive industry.     

Model hydrophobing compounds with nitrogen or sulphur atoms in oxyethylene structures,as modifiers of silica filler

Results of studies are presented on effect of new model compounds, applied to modify precipitated silica, on reinforcing of butadiene-styrene rubber vulcanizates filled with modified silica. Precipitated silica applied for the pur pose has been obtained according to our own procedure. Estimation of heats of immersion, mainly in benzene, has documented effect of model compounds involving hydrophobization of silica surface.For comparative reasons, results of strength tests have also been presented on vulcanizates of butadiene-styrene rubber filled with silica modified with a recognized coupling agent-mercaptosilane A-189.     

Effect of some pyrimidine thiol derivatives on the vulcanization of various elastomers

Some pyrimidine thiol derivatives were synthesized and tested in rubber formulations. They were incorporated in natural rubber, styrene butadiene rubber and polychloroprene mixes. It was found that their influence on the vulcanization reaction increases as the inductive effect of substituents attached to the nitrogen atom increases. The activity of investigated compounds falls in the same order according to their chemical structure for the different types of rubber.     

Vinyl ester resin modified with silicone-based additives: III. Curing kinetics

Silicone-based additives have been used as fire retardants for thermoplastics with the advantageous of improving the processing and the impact resistance of the polymers. In this work the influence of these additives on the curing kinetics of a vinyl ester resin was studied. Three silicone-based additives were used to modify the properties of the vinyl ester resin. The principal differences between them are the functional groups inserted in the polydimethylsiloxane chains. The additives were dispersed in the resin containing a commonly used mixture of initiator and catalyst methylethylKetone peroxide and cobalt-II octanoate, respectively. For some reactional mixtures N,N-dimethylaniline (DMA) was used as promoter. Differential scanning calorimetry (DSC) was used to perform the non-isothermal cure of the non-modified resin and of the resins modified with the additives. Ozawa´s, Kissinger´s and Ozawa´s isoconversional methods were used to determine the kinetic parameters. For resin cured in absence of DMA the silicone-based additives act as retardants for the curing reaction, a typical diluent effect, while in presence of this promoter the reaction enthalpy as well as the reaction rate were improved. This effect was attributed to specific interactions and reactions between DMA and the silicone-based additives that changed the curing mechanism as well as controlled the phase segregation.     

Experimental branching results for diene polymers by use of gel-permeation chromatography

Branching analyses in styrene–butadiene rubbers and polybutadiene rubbers have revealed large differences in branching between rubbers polymerized in different ways. The functionalities of several star-branched solution-polymerized styrene–butadiene rubbers were calculated and compared to their expected structures. Emulsion-polymerized polybutadiene rubber and a series of solution-polymerized polybutadienes made with different catalysts had different degrees of random branching, and evidence is presented indicating that the different available catalyst systems provide some latitude in making rubbers of different branching contents. Random branching analyses on a series of emulsion-polymerized styrene–butadiene rubbers revealed the dependency of branching on molecular weight and molecular weight distribution. The influence of polymerization temperature on the branching of emulsion-polymerized styrene–butadiene rubber was also studied.     

Secondary ion and laser ablation mass spectrometry for the quantitative characterization of styrene-butadiene copolymers

Styrene-butadiene copolymers were analyzed by static secondary ion mass spectrometry (S-SIMS) and laser ablation Fourier transform ion cyclotron resonance mass spectrometry (LA-FTICRMS) to obtain quantitative information based on specific ions. Silver deposition was performed on polystyrene, butadiene rubber and styrene-butadiene rubber. Under these experimental conditions, new secondary ions were detected, in particular silver-cationized butadiene [M(butadiene) - Ag](+) and styrene [M(styrene) - Ag](+) monomers. In contrast, LA-FTICRMS experiments did not require pretreatment. At high laser power density, UV photons (193, 266 and 355 nm) allowed the detection of styrene and butadiene monomers at m/z 104 and 54, respectively. The use of the observed ions by SIMS or LA-FTICRMS ensures that quantitative information on the relative distribution of each monomer is obtained. However, the silver coating thickness in the SIMS experiment seems to have an important influence on the quantitative information obtained. For LA-FTICRMS experiments, the best results are obtained at a wavelength of 355 nm.