橡胶微观结构因素对声障板吸声性能的影响

选择丁苯橡胶(SBR)和丙烯腈(CN)含量为36%~41%的丁腈橡胶(NBR),分别与氯化丁基橡胶(CIIR)共混,研究了SBR和NBR两种橡胶由于微观结构不同对声障板吸声性能的影响。由于微观结构的差异,SBR与NBR相比,其与丁基橡胶的共混(并用)胶料在0.5~3 MPa静水压力和3.5~7 k Hz频率范围条件下,吸声性能对静水压力的敏感性较低,且在试验的整个静水压力范围和频率范围尤其在1.5~3.5 k Hz频段具有更高的吸声性能。     

The effects of electron beam irradiation on the thermal properties,fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber blends

The effects of electron beam (EB) irradiation on the thermal properties, fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile–butadiene rubber (SBR/NBRr) blends were investigated. The SBR/NBRr blends were prepared at 95/5, 85/15, 75/25, 65/35, or 50/50 blend ratios with and without the presence of a 3 part per hundred rubber (phr) of polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). Results indicate that the crystallisation temperature (T_c) observed in polymeric blends is due to the alignment of polymer chains forming a semi-crystalline phase. Addition of TMPTA helps to align polymer chains through crosslinking. More crosslinking occurred between polymer blends with the help of TMPTA, upon irradiation. The improvement in fatigue life can also be associated with the stabilisation of SBR/NBRr blends upon irradiation and irradiation-induced crosslinking, which was accomplished with relatively low radiation-induced oxidative degradation in the presence of TMPTA. The tensile properties of both blends decreased over the periods of environmental exposure due to the effect of polymer degradation. After 6 months, the irradiated SBR/NBRr blends could not retain better retention [mainly with 25, 35 or 50 phr of recycled acrylonitrile–butadiene rubber (NBRr) particles] due to the samples becoming brittle over the long period of outdoor exposure.     

Use of rice husks as potential filler in styrene butadiene rubber/linear low density polyethylene blends in the presence of maleic anhydride

In the present study, rice husks filled styrene butadiene rubber (SBR)/linear low density polyethylene (LLDPE) 50/50 blends with a compatibilizer, maleic anhydride (MAH) were prepared using a brabender plasti-corder. Virgin SBR/LLDPE blend was also prepared. The physico-mechanical as well as dielectric properties were investigated. Increasing MAH concentrations in SBR/LLDPE blends resulted in an increase in the tensile strength, elongation at break and hardness. After a certain concentration (2.5 phr), a reduction in these properties was found. On the other hand an increase in the dielectric properties as well as in the mass swell in both toluene and oil with MAH was noticed. After certain concentration of rice husk filler (25 phr) an abrupt increase in permittivity ε′ and dielectric loss ε″ was obtained. These results are supported by the mechanical properties measurements. The scanning electron microscopy (SEM) indicates that the presence of MAH increases the interfacial interaction between SBR/LLDPE blends on one hand and also rice husk filler and the blend on the other hand.     

用红外光谱法研究橡胶/炭黑的界面相互作用

用红外光谱法(FI-IR)研究了橡胶微观结构、炭黑表面基团对橡胶/炭黑的界面相互作用的影响。研究表明,炭黑加入后各分子基团的振动均发生红移。炭黑与富电子的分子链相互作用大,即天然橡胶(NR)>丁基橡胶(BR)>丁苯橡胶(SBR)>丁腈橡胶(NBR);对侧基的影响小于对主链的影响。极性基团丙烯腈含量(ACN)增加,除ν(C≡N)外碳链上的其它基团均发生蓝移,且支链上双键基团所受影响最大。炭黑加入后,减弱了ACN含量增加对链段间作用力的影响,随ACN含量增加各基团蓝移较纯胶的小。门尼黏度仅影响δCH2的振动峰位。     

The effect of zinc oxide–phosphate core–shell pigments on the properties of blend rubber composites

In this work the rheological, physico-mechanical, thermal and morphology studies were performed on a blend of EPDM/SBR (ethylene propylene diene monomer/styrene butadiene rubber) (50/50) loaded with a new prepared core–shell pigment based on a core of zinc oxide which presents the major component of the prepared pigment (≈90%) covered with a shell of phosphate, this shell comprises only about (≈10%). The new pigments were added in different concentration to the rubber blend and were compared to blends pigmented with commercial zinc oxide and zinc phosphate. The results showed that the new pigments exhibited better rheometric, and physico-mechanical properties. In addition, these prepared pigments showed decrease of equilibrium swelling in toluene solvent and increase in crosslink density for EPDM/SBR blend. The efficiency of prepared core–shell pigments were also evaluated by studying the surface morphology (SEM) and thermal properties TGA (thermal gravimetric analysis). The prepared pigments loading of 10 phr (parts per hundred parts of rubber) showed the optimum properties of EPDM/SBR blend than rubber loaded with higher concentration of the commercial pigments, which indicated that the new core–shell pigment is more economic with better performance than commercial zinc oxide and phosphates individually.     

Effect of different curing systems on the mechanical and physico-chemical properties of acrylonitrile butadiene rubber vulcanizates

In the present study, the effect of different curing systems including sulfur, dicumyl peroxide, dicumyl peroxide/coagent and radiation/coagent on the mechanical and physico-chemical properties of acrylonitrile butadiene rubber (NBR) was studied. In order to correlate, the effect of curing systems on rubber, the comparison was carried out at comparable value of volume fraction of rubber in swollen gel (V_r) for NBR vulcanizates. Mechanical properties like tensile strength, elongation at break, modulus, Young’s modulus, tearing strength and abrasion loss of vulcanizates have been followed up for comparison. In addition, physico-chemical properties like swelling ratio, soluble fraction, and cross-link density were investigated. On the other hand, the effects of fuel, thermogravimetric analysis, and thermal ageing have been studied.     

Fracture resistance of polyblends and polyblend matrix composites Part III Role of rubber type and location in nylon 6,6/SAN composites

The role of rubber particle type, location and morphology on toughening in blends of nylon 6,6 with styrene acrylonitrile (SAN), with and without fibre reinforcements was examined in this study. The rubber used was ethylene propylene diene monomer (EPDM) rubber and the results were compared to a previous study that used butadiene rubber. The compositions of the blends ranged from pure nylon 6,6 to pure SAN. EPDM rubber was chemically compatibilized with one of the matrix phases rather than grafted, as in the ABS. In order to study the effect of rubber location on fracture behaviour, the approach was to compatibilize EPDM with either the minor phase or the major phase component of the blend. Attention was focused on fracture initiation toughness and fracture propagation toughness, measured through the parameters J _IC and J _SS, respectively. J _SS refers to the steady-state, or plateau value of the material R-curve and was therefore a measure of total toughness which included the additional component derived from crack extension. The results indicated that EPDM rubber was not as effective a toughening agent as was butadiene in the Acrylonitrile Butadiene Styrene (ABS) system, primarily due to the morphology of EPDM and its interface character with the nylon 6,6 or SAN matrix. It was demonstrated that the embrittlement effects of a second rigid polymer phase can be mitigated by selectively adding rubber to that phase in the alloy or blend. With regard to the role of fibre reinforcement, a strong fibre matrix interface was found to be essential for toughening. Further, the extent of rubber toughening was larger when fibres were present than when fibres were absent, provided the fibre matrix interface was strong. Fibres also, like rubber, enhanced local matrix plasticity as well as reduced the embrittlement effects associated with a second polymer phase.     

Effect of carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN) concentration on thermal and mechanical properties of binary blends of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin

Six blend samples were prepared by physical mixing of epoxy resin with varying concentrations of liquid carboxyl-terminated butadiene acrylonitrile (CTBN) copolymer having 27% acrylonitrile content. The blend samples were cured with aromatic amine. A comparative study of Fourier-transform infrared (FTIR) spectra showed the modification as a result of chemical reactions between epoxide group, curing agent and CTBN. The tensile strength of cured blend samples decreased slightly from 11 to 46% where as the elongation-at-break showed an increasing trend with increasing rubber content, i.e., up to 25 phr, in the blend samples. Appreciable improvements in impact strength were also observed in the prepared blend systems. The glass transition temperature (T_g) of the epoxy resin matrix was slightly reduced on the addition of CTBN. The cured resin showed a two-phase morphology where the spherical rubber domains were dispersed in the epoxy matrix.     

Conductive rubber composites from different blends of ethylene-propylene-diene rubber and nitrile rubber

Conductive rubber composites were derived from different blends of ethylene-propylene-diene monomer (EPDM) rubber and acrylonitrile butadiene rubber (NBR) containing acetylene black. The electrical and mechanical properties of these composites were measured. The percolation limit for achieving high conductivity of conductive filler depends on the viscosity of the blend. The higher the viscosity, the higher is the percolation limit. The conductivity rises with increasing temperature, and the activation energy of conduction increases with the decrease in the loading of conductive filler and percentage of NBR in the blend. Electrical hysteresis and an electrical resistivity difference during the heating-cooling cycle are observed for these systems, which is mainly due to some kind of irreversible change occurring in the conductive networks during heating. The mechanisms of conduction of these systems were discussed in the light of different theories. It was found that the degree of reinforcement by acetylene black in blends compares with those in the pure components NBR and EPDM. This is due to incompatibility of two elastomers in the blend. This revised version was published online in November 2006 with corrections to the Cover Date.     

Modified phosphate pigments as high performance reinforcing materials for rubber vulcanizates

This study is focusing on the synthesis of novel modified micronized phosphate pigments as reinforcing materials for the vulcanizates of styrene-butadiene rubber (SBR), natural rubber (NR) and their blends. The metal phenyl phosphate pigments were prepared via co-precipitation process from the reaction of equimolar ratios of the disodium phenyl phosphate solution and the water soluble salts of the investigated metals. The white prepared phosphate pigments were introduced in the rubber formulations to replace carbon black the highly common and commercial reinforcing material in rubber vulcanizates. The rheometric characteristics, physico-mechanical properties in addition to the accelerated aging properties of the rubber vulcanizates were investigated, discussed and interpreted in the light of previous studies. The results showed that, phenyl phosphate pigments exercised a great effect on the rheological characteristics (scorch time, cure time…etc.), and achieved high performance and pronounced mechanical properties. The stress and strain at yield and at rupture of the loaded rubber with modified phosphates are better than that loaded with carbon black and Hisil e.g. tensile strength data were (20.0–23.4), 18.01 MPa and 15.05 for rubber blend vulcanizates loaded with 30 phr of modified phosphate pigments, carbon black and Hisil, respectively.     

Investigations on the addition of styrene butadiene rubber in natural rubber and dichlorocarbene modified styrene butadiene rubber blends

This paper focuses on the use of styrene butadiene rubber (SBR) as a viscosity modifier in novel blends of natural rubber (NR) and dichlorocarbene modified styrene butadiene rubber (DCSBR). The processing characteristics, vulcanisation kinetics, stress-strain behaviour, mechanical properties and low temperature transition of the blends have been examined in order to analyse the influence of SBR in the blends. The change in cross-link density values from stress strain behaviour and equilibrium swelling data has been correlated with the technological properties of the blends. The excellent mechanical properties and the increased cross-link density in blends in the presence of 5—10 phr of styrene butadiene rubber reveals the viscosity modifying action of SBR in NR/DCSBR blends. The variation in viscosities of these blends with the addition of SBR is reflected in the DSC thermograms. The resulting blends show very high resistance to thermal ageing as compared to those without SBR.     

Gamma irradiation aging of NBR/CSM rubber nanocomposites

The effect of gamma-irradiation on the acrylonitrile butadiene/chlorosulphonated polyethylene rubber blends (NBR/CSM) based nanocomposites containing carbon black (CB) and silica filler (Si) were investigated by TG-DTG and ATR-FTIR techniques. The silica (with primary particle size of 22 nm) was added in content of 0, 10, 20 and 30 phr and carbon black (with primary particle size 40–48 nm) was added in content of 30 phr and rubber blend compounds were prepared. The obtained elastomeric materials were aging to different γ-irradiation doses (100, 200 and 400 kGy). The cure and mechanical properties of obtained nanocomposites were determined. Incorporating 20 phr of silica to the control NBR/CSM rubber blends containing 30 phr CB resulted 152% increase in tensile strength, 116%, in elongation at break and 142% modulus at 100% elongation, according to synergistic effect between the fillers. FTIR measurements of aged samples estimated the formation of alcohols, ethers and small amounts of lactones, anhydrides, esters and carboxylic acids after exposure to lower doses of γ-radiation (100 kGy). On the basis of the obtained spectra the formation of shorter polyene sequences and aromatic rings in aged elastomeric samples are assumed. The results show that 30 phr of carbon black (CB) and 20 phr of silica are needed for the best gamma aging resistance of NBR/CSM rubber nanocomposites. The result of radiation exposure is decrease in mechanical properties. The dose at which ultimate mechanical properties decreased was at 200 kGy. TG-DTG measurements estimated decrease in thermal stability of gamma-irradiated NBR/CSM rubber blend based nanocomposites. Silica reinforced NBR/CSM rubber blend had better radiation resistant than carbon black. Rough and heterogeneity of fracture surfaces has been observed for NBR/CSM rubber blends filled with silica. More uniform morphology of fracture surfaces according to high polymer–filler interaction and low filler–filler interaction has been observed for CB/Si filled NBR/CSM rubber blend.     

滑动接枝共聚物/丁腈橡胶复合材料及其阻尼性能

将丁腈橡胶（NBR）与预硫化滑动接枝共聚物（SGC）混合制备SGC/NBR复合材料,并采用DSC、橡胶加工分析仪（RPA）、TEM和FTIR等研究了预硫化温度对复合材料内部结构及动态力学性能的影响。结果表明:SGC作为分散相在NBR基体中形成了海岛结构,且与NBR 大分子之间形成了分子间氢键,使两相相容性较好并形成了明显的界面作用区。界面作用区的存在使SGC/NBR复合材料的玻璃化转变温度与纯NBR基体相比升高,同时使复合材料的拉伸强度和拉断伸长率等力学性能显著增强,并出现了明显的拉伸取向。由于SGC与NBR之间分子链的扩散以及氢键作用,使分子链σ单键的内旋转受阻,旋转时需要消耗能量以克服所受的阻力,造成SGC/NBR复合材料的损耗因子明显增加,其中预硫化温度为160℃时阻尼效果最好。SGC/NBR复合材料在建筑桥梁振动频率应变变形范围内表现出优异的损耗性能,可应用于高阻尼隔震支座。      

Synthesis and application of functionalised acrylonitrile-butadiene rubber for enhancing recyclability of poly(vinylchloride) (PVC) and poly(methylmethacrylate) (PMMA) in recycled blends

The current investigation deals with the synthesis and application of functionalised acrylonitrile-butadiene rubber (NBR-g-MAH) as an impact modifier and compatibilising agent in the recycled blend of poly(vinyl chloride) and poly(methylmethacrylate). The performance of NBR as an impact modifier was improved by grafting with maleic anhydride. The varied concentration of NBR-g-MAH/NBR mixture has differed effects on the mechanical, thermal and morphological properties of the recycled blend. The recycled blend with 9 wt% of NBR-g-MAH/NBR mixture shows optimum impact strength and elongation-at-break. Moreover, Fourier-transform infrared spectroscopy analysis confirms interactions with polar functionalities in the recycled blends. Differential scanning calorimetry and scanning electron microscope analyses suggest partial miscibility as well as compatibility of the polymeric constituents in the blend. Additionally, thermal gravimetric analysis shows higher thermal stability for the modified recycled blend as compared to its parent blend.     

Utilization of waste expanded polystyrene: Blends with silica-filled natural rubber

Expanded polystyrene (EPS) constitutes a considerable part of thermoplastic waste in the environment in terms of volume. In this study, this waste material has been utilized for blending with silica-reinforced natural rubber (NR). The NR/EPS (35/5) blends were prepared by melt mixing in a Brabender Plasticorder. Since NR and EPS are incompatible and immiscible a method has been devised to improve compatibility. For this, EPS and NR were initially grafted with maleic anhydride (MA) using dicumyl peroxide (DCP) to give a graft copolymer. Grafting was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. This grafted blend was subsequently blended with more of NR during mill compounding. Morphological studies using Scanning Electron Microscopy (SEM) showed better dispersion of EPS in the compatibilized blend compared to the noncompatibilized blend. By this technique, the tensile strength, elongation at break, modulus, tear strength, compression set and hardness of the blend were found to be either at par with or better than that of virgin silica filled NR compound. It is also noted that the thermal properties of the blends are equivalent with that of virgin NR. The study establishes the potential of this method for utilising waste EPS.     

高分子电解质中锂盐与高分子的相互作用

以共聚氯醚橡胶和丁腈橡胶的溶液共混物为主体 ,含浸 L i Cl O4 / PC液 ,制得两相高分子电解质。用DSC、FT- IR和 X射线衍射法研究了在高分子中的存在状态及其与高分子的相互作用。结果表明 ,L i+主要与 ECO中的醚氧原子配位 ,且被 PC溶剂化 ,L i Cl O4 完全溶解在体系中。亦有少量 L i+与 NBR中的 -CN键发生作用。含浸 L i Cl O4 / PC后 ,ECO/ NBR的相容性提高     

Evaluation of clay hybrid nanocomposites of different chain length as reinforcing agent for natural and synthetic rubbers

Polymer nanocomposites are one of the highly discussed research topics in recent time. It has been reported in the present paper the preparation and the properties of different nanoclays based on sodium montmorillonite (bentonite) and some organic amines of varying chain lengths (dodecylamine, hexadecylamine and octadecylamine) beside amine-terminated butadiene–acrylonitrile copolymer (ATBN). The hybrid clays have been characterized with the help of Fourier Transform Infrared spectroscopy (FTIR).Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Wide angle X-ray diffractions (WXRD), and Thermogravimetric analysis (TGA). X-ray results showed that the intergallery distance of the clay is increased as a result of the intercalation of the amines and ATBN. The nanocomposite clays were incorporated in natural and synthetic rubbers (NR, SBR and NBR). The physico-mechanical properties are greatly improved with loading low concentrations of the nanocomposite clays compared with carbon black.     

NR/CSM/biogenic silica rubber blend composites

Biogenic silica (BSi) was added at different ratios to some polymer blends of polyisoprene rubber (NR) and chlorosulphonated polyethylene rubber (CSM) cured by conventional sulfur system. The reinforcing performance of the filler was investigated using rheometric, mechanical and swelling measurements, differential scanning calorimetry (DSC), thermogravimetric (TGA) and scanning electron microscopy (SEM) analysis. There was a remarkable decrease in the optimum cure time (t_c90) and the scorch time (t_s2), which was associated with an increase in the cure rate index (CRI), with filler loading up to 30 phr in the different blend ratios. The tensile strength and hardness was 4–5 Sh-A higher in the case for the different blend compositions, while the resistance to swelling in toluene became higher. SEM photographs show that the filler is located at the interface between the different polymers which induces compatibilization in the immiscible blends. DSC scans of the filled blends showed shifts in the glass transition temperatures Tg which can be attributed to the improve interfacial bonding between filler and NR/CSM matrix. A higher thermal stability of NR/CSM/BSi composites was detected.     

混炼工艺对SBR/BR/CB共混硫化胶性能的影响

为了研究混炼工艺对最终硫化胶性能的影响,利用HAAKE转矩流变仪对不同配比的丁苯橡胶/顺丁橡胶/炭黑进行混炼,混炼采用两种不同的混炼顺序——一种是炭黑首先与丁苯橡胶(SBR)混炼,然后加入顺丁橡胶(BR)混炼;另一种是BR与炭黑混炼之后再加入SBR进行混炼。对制得共混物进行结合胶含量、拉伸以及动态力学性能测试。结果显示,在相同配比下,炭黑首先跟份数多的富相橡胶混炼可以得到较多的结合胶,有利于体系的补强;动态力学测试结果表明硫化胶的粘弹特性受第一段混炼所用橡胶的影响较大,炭黑与柔顺性较好的BR先混炼,共混体系工艺相容性较好。     

基于傅里叶变换红外光谱的航空丁腈橡胶鉴别方法

介绍了航空丁腈橡胶(NBR)的编号规则,分析了傅里叶变换红外光谱(FTIR)定量法鉴别航空丁腈橡胶的理论依据。将航空丁腈橡胶试样经无水乙醇萃取、烘干后,采用红外光谱定量法统计分析了光谱中特征吸收峰(-C≡N基与-CH=CH₂基)的吸光度比值R与橡胶生胶丙烯腈(CAN)含量的半定量对应关系和鉴别橡胶的种类。结果表明:生胶丙烯腈含量越高,特征峰吸光度比值R越大,具有线性对应关系。依据R推断丁腈橡胶的生胶类型,再结合橡胶硫化硬度,可对航空丁腈橡胶作进一步鉴别。对于不同类型生胶并用的丁腈橡胶而言,并用胶的某些特征官能团可作为橡胶鉴别的依据。