Filler–polymer interactions in both silica and carbon black‐filled styrene–butadiene rubber compounds

Bound rubber in a filled rubber compound is formed by physical adsorption and chemisorption between the rubber and the filler. Styrene–butadiene rubber (SBR) is composed of four components of styrene, cis‐1,4‐, trans‐1,4‐, and 1,2‐units. Filler–polymer interactions in both silica and carbon black‐filled SBR compounds were studied by analyzing microstructures of the bound rubbers with pyrolysis‐gas chromatography. Differences in the filler–polymer interactions of the styrene, cis‐1,4‐, trans‐1,4‐, and 1,2‐units were investigated. The filler–polymer interactions of the butadiene units were found to be stronger than that of the styrene unit. The interactions of the cis‐1,4‐ and trans‐1,4‐units were stronger with carbon black than with silica, whereas the 1,2‐unit interacted more strongly with silica than with carbon black. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 439–445, 2001     

Filler‐polymer interactions of styrene and butadiene units in silica‐filled styrene–butadiene rubber compounds

Styrene–butadiene rubber (SBR) is a copolymer of styrene and butadiene, and the butadiene unit is composed of cis‐1,4‐, trans‐1,4‐, and 1,2‐components. Filler‐polymer interactions of each component of SBR in silica‐filled SBR compounds were examined by microstructure analysis of the bound and unbound rubbers. The composition ratio of butadiene and styrene units (butadiene/styrene) of the bound rubber was higher than that of the compounded rubber. Of the butadiene units, the 1,2‐component of the bound rubber was more abundant than the cis‐1,4‐ and trans‐1,4‐components. The filler‐polymer interaction of the butadiene unit with silica was stronger than that of the styrene unit, and the interaction of the 1,2‐component was stronger as compared with the others. The butadiene–styrene ratio of the bound rubber of the compounds containing the silane coupling agent was lower than for the compounds without the silane. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 577–584, 2004     

Determination of bound rubber composition of filled SBR/BR blend compounds by analysis of the unbound rubber composition and bound rubber content

Analytical method for determination of the bound rubber composition of a filled SBR/BR blend compound was developed using measurement of the bound rubber content and microstructural analysis of the unbound rubber composition. Various filled SBR/BR blend compounds with different blend ratios were prepared using SBRs with different microstructures. This method included measurement of the bound rubber content, extraction of the unbound rubber, microstructural analysis of the unbound rubber composition, and process for determination of the bound rubber composition. Composition of the unbound rubber was analyzed using liquid proton nuclear magnetic resonance spectroscopy (H-NMR) and transmission Fourier transform infrared spectroscopy (FTIR). It was found that the analytical results using H-NMR had less experimental errors than those using transmission-FTIR. The raw SBR/BR blends were also analyzed in order to evaluate level of the experimental errors. Average SBR/BR ratios of the unbound rubbers were obtained using the 1,2- and 1,4-unit contents determined by the H-NMR analysis. The bound rubber compositions were obtained using the bound rubber contents and the average unbound rubber compositions. It was found that most of the bound rubbers had higher SBR ratios than the formulation value.     

不同链化学结构丁苯橡胶与天然橡胶混容性研究

选择了三种丁苯橡胶 (SBR)———乳聚丁苯胶 (ESBR)、溶聚丁苯C(SSBR (C) )及溶聚丁苯B(SSBR(B) ) ,用红外光谱 (FTIR)分析了它们的链化学结构 .同时 ,用动态力学谱 (DMA)和示差扫描量热谱 (DSC)研究了这三种SBR与天然橡胶 (NR)的混容性 .结果表明 ,SSBR(B)与NR具有很好的混容性 .三种SBR与NR混容性的差别 ,与SBR链化学结构不同有关     

Thermal stability and flammability of nanocomposites made of diene rubbers and modified halloysite nanotubes

This paper presents a method of modification of halloysite with the use of aqueous solutions of halogens and an alcoholic solution of boric acid. The effect of modified nanoadditives on the thermal properties, flammability, and fire hazard of peroxide and sulfur vulcanizates of butadiene–acrylonitrile (NBR) and butadiene–styrene (SBR) rubbers was described and assessed. The test results obtained by spectrometric methods, oxygen index, and cone calorimeter were interpreted from the point of view of the chemical structure of the investigated diene elastomers and the particular method of halloysite modification. The analysis of values obtained by the method of cone calorimetry it confirms that most NBR and SBR vulcanizates filled with modified halloysite are more resistant to fire when compared with material without modification. In addition, the modified halloysite are crucial in making self-extinguishing elastomeric materials.     

Thermal decomposition of polybutadienes by pyrolysis gas chromatography

The thermal decomposition of cis-1,4-, trans-1,4-, and 1,2-polybutadienes (PBD) in the temperature range 450–900°C was investigated by pyrolysis gas chromatography (PGC). The cis- and trans-PBDs have closely similar product distribution and can be readily distinguished at lower temperatures of pyrolysis from the 1,2-PBD by the low amount of vinyl cyclohexene (VCH) produced by the 1,2 species. The amount of butadiene (BD) produced by 1,2-PBD varies with the tacticity of the polymer; the greater syndiotactic yields a lesser amount of BD. A method of determining the 1,4 and the 1,2 contents of PBD based on the ratios of peak heights of ethylene (C2) to VCH, propylene (C3) to VCH, and BD to VCH is presented. The advantages of this method are discussed. The nature and composition of the products of pyrolysis in the temperature range 540–900°C are presented and the mechanism of degradation at these elevated temperatures is explained.     

Filler-polymer interactions in filled polybutadiene compounds

Bound rubber in a filled rubber compound is formed by physical adsorption and chemisorption between the rubber and filler. Polybutadiene (PB) is composed of three components of 1,2-, cis-1,4-, and trans-1,4-units. Filler-polymer interactions in PB compounds filled with carbon black or silica were studied by analyzing microstructures of the bound rubbers with pyrolysis-gas chromatography. Differences in the filler-polymer interactions of the 1,2-, cis-1,4-, and trans-1,4-units were investigated. The filler-polymer interaction of the 1,2-unit is stronger than those of the cis-1,4- and trans-1,4-units. The interaction of the 1,2-unit with silica is stronger than with carbon black. Bound rubber content is decreased by treatment with ammonia. Change of the bound rubber composition after the ammonia treatment was also studied.     

Application of multi-capillary column – ion mobility spectrometry (MCC-IMS) in rubber chemistry and technology

In this paper the possibility for authentication and differentiation of various styrene butadiene rubbers (SBRs) was investigated. Seven types of SBR were analyzed by multi-capillary column (MCC) ion mobility spectrometer (IMS) and their spectra compared. The analysis of volatile organic compounds (VOCs) releasing from the rubbers revealed the presence of characteristics signals, which can be assigned only to a specific material. Such “markers”, when defined for other polymer materials, can be used for their authentication. In the second part of the paper, the blend of epoxidized natural rubber and poly-3-hydroxybutyrate-co-4-hydroxybutyrate (ENR/P(3,4)HB) was subjected to different types of aging. MCC-IMS spectra of not aged, thermal, climatic and UV aged samples were collected and differences between the signals discussed. The study showed possibility of authentication of polymeric materials and processes. The paper is a some kind of introduction to the use of analytical properties and advantages of MCC-IMS technique in chemistry, technology and exploitation of polymer materials.     

Dynamic mechanical properties of cross-linked rubbers. V. An approximate analysis of the modulus contributions of trapped and untrapped entanglements

Using the criterion that a coupling entanglement in a polymer network is trapped if all four strands radiating from it terminate in chemical cross-links (an approximation to a more rigorous treatment of Langley), an equation is derived relating the equilibrium modulus to the magnitude of the compliance in the frequency region where all coupling entanglements, whether trapped or not, contribute to the elasticity. The latter value is estimated from the storage compliance at the frequency where the storage compliance of the uncross-linked polymer corresponds to the entanglement compliance derived from integration over the loss compliance. The theory agrees rather well with data on vulcanizates of natural rubber. For 1,4-polybutadiene and styrene–butadiene rubbers, the agreement is somewhat less satisfactory, but the results support the hypothesis that the low-frequency losses observed in lightly cross-linked rubbers are due to relaxation of untrapped entanglements.     

In situ modification of pyrolysis products of macromolecules in an analytical pyrolyser

An application of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) is presented for the fast on-line testing of solid catalysts activity in upgrading pyrolysis oils and/or gases of natural and synthetic polymers. Evaluation of the chemical conversion by a catalyst is simply and quickly performed in a Py-GC/MS instrument without any modification either of the micropyrolyser or the GC inlet. The pyrolysis products evolved from the sample pass through catalyst microbeds of some mm length and the GC/MS analysis of the converted products is performed on-line. Modification of polyolefin, styrene copolymer, polyester, polyamide, brominated epoxy resin and wood pyrolysate was carried out applying sodium type zeolite and medium acidic mesoporous aluminosilicate in the microbeds. The primary pyrolysis products are converted over the microbeds due to the catalytic activity of the bed material. Intramolecular hydrogen transfer reactions promoted by Na zeolite results in the isomerisation of alkenes and alkadienes evolved by pyrolysis from polyethylene and polypropylene. These basic catalysts were found to be effective for the elimination of brominated phenols from the pyrolysate of brominated epoxy resin. Cracking of alkane and alkene oligomer products of polyolefins to light isoalkenes occur over acidic mesoporous aluminosilicate. Certain compounds with polar groups evolved from polyester, polyamide, cellulose or lignin are removed by this catalyst. Alkenylaromatic compounds are simultaneously hydrogenated and polyaromatised in pyrolysis oils of styrene copolymers over both acidic and basic aluminosilicate catalysts tested.     

Colouring Agents for SBR Vulcanizates and Their Effects on Ageing and UV Radiation Resistance

Summary: Metal free and some metal-perylene polymers as well as some metal phthalocyanine polymers were incorporated into styrene butadiene rubber (SBR) compounds as colouring agents. The ageing and UV resistance of the vulcanizates obtained were studied in terms of their mechanical properties. The results obtained revealed that cobalt perylene and cobalt phthalocyanine polymers showed superior performance in SBR vulcanizates against thermal ageing and UV radiation. The optimum concentration of cobalt phthalocyanine polymer was found to be 1 phr (parts per hundred parts of rubber).     

Microstructural analysis of poly(vinylidene fluoride) using benzene derivative pyrolysis products

Poly(vinylidene fluoride) (PVDF) was pyrolyzed, and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to develop a method for identification of the microstructures of head-to-tail (H-T), tail-to-tail (T-T), and head-to-head-to-tail-to-tail (H-H-T-T) sequences. Key pyrolysis products to determine the relative degrees of the microstructures were benzene derivatives. 1,4-Difluorobenzene, 1,2,4-trifluorobenzene, and 1,3,5-trifluorobenzene were major pyrolysis products as benzene derivatives. 1,3,5-Trifluorobenzene and 1,2,4-trifluorobenzene were formed from two HF-eliminated PVDF by 1,6-HF elimination and 1,6-rearrangement, while 1,4-difluorobenzene was generated from two HF-eliminated PVDF by 1,6-H₂ elimination and 1,6-rearrangement. 1,3,5-Trifluorobenzene was generated from the H-T sequence, whereas 1,4-difluorobenzene was formed from the T-T one. 1,2,4-Trifluorobenzene can be formed from the H-H-T-T sequence. Relative component ratios of the H-T, T-T, and H-H-T-T sequences of PVDFs can be estimated by comparing relative abundances of the benzene derivative pyrolysis products.     

119Sn-NMR evidence for 2,1-initiation in the anionic polymerization of butadiene with trialkyltin lithium

Low molecular weight polybutadienes and styrene butadiene copolymers were anionically prepared with trialkyltin lithium initiator and end-capped with either hydrogen or a trialkyltin group. These polymers were prepared with a variety of microstructures. Analysis by ¹¹⁹Sn-NMR and comparison to model compounds showed no cis-1,4-initiation of the butadiene. The initiation sites found were trans-1,4- and both 2,1- and 1,2-additions of the tin-lithium bound to a 1,3-butadiene. At low levels of added polar modifier, the 2,1-addition predominated. The ¹¹⁹Sn-NMR spectra allowed the assignment of the sequence distribution associated with the nearest eight main chain carbon atoms (2-4 monomer units) adjacent to the tin end groups. No initiation could be detected involving the styrene comonomer, but incorporation of styrene was detected as the first or second unit after initiation. The reaction of the allyl-tin end groups of these polymers with 1,2-napthoquinone was followed by NMR and was used to assign the peaks associated with 1,2-addition of the trialkyltin lithium to 1,3-butadiene. © 1995 John Wiley & Sons, Inc.     

生物质主要组分低温热解研究

利用热重分析仪和裂解气质联用仪进行生物质主要组分低温热解特性研究。热重实验结果表明,生物质主要组分的热稳定性为：纤维素>木质素>半纤维素。半纤维素主要热解温度在210℃～320℃,而纤维素和木质素的主要热解温度分别在310℃～390℃和200℃～550℃。裂解气质联用实验考察不同温度对生物质主要组分低温热解产物的影响。半纤维素热解产物主要有乙酸、1-羟基-丙酮和1-羟基-2-丁酮,纤维素热解产物主要包括左旋葡聚糖和脱水纤维二糖,而木质素热解产物主要是邻甲氧基苯酚。     

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.     

固体核磁共振法测定硫化丁苯橡胶中的苯乙烯

采用魔角旋转固体核磁碳谱法(MAS–~(13)CNMR)测定硫化丁苯橡胶中的苯乙烯含量。通过固体核磁碳谱解析,对丁苯橡胶中苯乙烯、1,2-乙烯基、1,4-丁二烯的特征峰进行归属分析,以固体核磁外标法定量。对已知苯乙烯含量的标准样品进行测定,绘制校正曲线,结果显示理论苯乙烯含量与固体核磁法计算结果成良好的线性关系,线性相关系数(r~2)为0.97。经标准曲线校正后的苯乙烯含量接近于真实值,计算结果的相对误差小于5%,测定结果的相对标准偏差为0.31%(n=6)。该方法适用于单一胶种的硫化丁苯橡胶中苯乙烯含量的检测。     

Effect of Gamma Radiation-grafted Aramid Chopped Fibers as the Reinforcing Filler in Styrene–Butadiene Rubber Mixtures

Poly(p-phenylene-terephthalamide) PPTA chopped fibers, known as Kevlar 49 and related to aramid fibers, were subjected to graft copolymerization with styrene under the effect of gamma radiation. The effects of different parameters including irradiation dose, type of solvent and monomer concentration on the graft yield were studied. The surface-modified chopped fibers were introduced in styrene–butadiene rubber (SBR) mixtures. The properties of rubber mixtures and their corresponding vulcanizates were markedly affected depending on the fiber concentration. Grafting of styrene on to chopped PPTA fibers improves the mechanical properties of SBR–PPTA composites, especially in the presence of additional crosslining systems based on benzoyl peroxide EDMA (ethylene dimethacrylate) system. © 1997 John Wiley & Sons, Ltd.     

Morphology dependence of crystallization of natural rubber in blends

Crystallization of natural rubber (NR) was investigated in different morphology for NR/styrene butadiene rubber (SBR) blend and NR/polystyrene-(b)-polyisoprene (SI)/polystyrene (PS) blend. A purified NR (PC-TE) was prepared from pale crape via transesterification. In the blends, PC-TE formed various morphologies; that is, matrix phase, island phase and continuous phase with a nano-scale, respectively, in dependence upon the ratio of the rubbers. The crystallization rate of the blends was also significantly associated with the morphology of the rubbers.     

Evolution of the crosslink structure in the elastomers NR and SBR

An experimental positron annihilation lifetime spectroscopy (PALS), differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) study of the effect of the advance of the crosslinking reaction on the free volume in a copolymer of styrene–butadiene and natural rubbers was carried out. The crosslink density developed in SBR specimens with different sulfur contents and cure temperatures was studied. SAXS technique was applied to study the process of crosslinking in NR as a function of the cure temperature. Finally, a study of different SBR/NR blends is presented using PALS and DSC.     

Localization of Failures in Structural Order of <Emphasis Type="Italic">trans</Emphasis>-1,4-Butadiene Units in Interdefective Regions of a Butadiene-Nitrile Elastomer Matrix

The fractional free volume of chains passing and incorporated into the ordered structures of segments in trans-1,4-configuration in the copolymers of butadiene and acrylonitrile at different content of acrylonitrile units is calculated in order to determine the localization of order disturbances of butadiene trans-1,4-units. Amorphization of the structure occurs in the immediate vicinity of structural defects of acrylonitrilebutadiene rubbers formed by alternating acrylonitrile and trans-1,4-units of butadiene as well as cis-1,4-and 1,2-isomers of butadiene.