Epoxidized natural rubber/dicarboxylic acid self-vulcanized blends

Curing behaviour as well as mechanical properties of binary blends of epoxidized natural rubber (ENR) and dodecanedioic acid (DA) were investigated for development of self-vulcanizable elastomer blends. Cross-linking reaction at 180 °C of reactive functional rubber containing 25 and 10 mol% epoxide groups was followed by rheology. The properties of the cured materials were studied by dynamic mechanical analysis, stress-strain experiments, and DSC measurements. It was shown that a specific ratio ENR/DA gave rise to optimum mechanical properties. This ratio decreases together with the epoxidation level of the rubber. DSC measurements revealed that the glass transition temperature of the cured material increases nonlinearly at high concentrations of cross-linking agent. By comparing cross-linking with DA and reaction with monofunctional lauric acid, this behaviour was attributed to polar interactions due to free carboxylic groups of pending diacid grafts.     

Reactive bonding of natural rubber to metal by a nitrile–phenolic adhesive

The mechanism of adhesive bonding of rubber to metal using an interlayer of bonding agent (adhesive) is discussed with respect to various physical and chemical events such as adsorption at the metal surface, chemical crosslinking within the adhesive, interdiffusion, and formation of interpenetrating networks at the rubber–adhesive interface. An investigation on the peel strength of a natural rubber (NR)–adhesive–metal joint, made by vulcanization bonding using nitrile–phenolic adhesive containing various concentrations of toluene diisocyanate–nitrosophenol (TDI–NOP) adduct, is presented. A single‐coat adhesive, consisting of a p‐cresol phenol formaldehyde resin, nitrile rubber (NBR), and vulcanizing agents in methyl ethyl ketone solvent, was selected for the study. Considerable improvement in the peel strength was obtained by the incorporation of TDI–NOP adduct into the nitrile–phenolic adhesive. The peel strength increases as the concentration of TDI–NOP adduct in the adhesive composition increases, then levels off with a transition from interfacial failure to cohesive tearing of rubber. The peel strength improvement is believed to be attributed to the interfacial reactions between the bonding agent and natural rubber, when TDI–NOP adduct is incorporated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2597–2608, 2001     

Epoxidized natural rubber as a reinforcement modifier for silica‐filled nitrile rubber

Hydrated silicas impart better physical properties to polar rubbers, compared to those of hydrocarbon rubbers. However, to achieve optimum properties silane coupling agents are crucial in such formulations. Epoxidized natural rubber (ENR) in small proportions is used as a reinforcement modifier for silica‐filled nitrile rubber (NBR). Two systems of cure were used: N‐cyclohexyl‐ 2‐benzthiazyl sulfenamide (CBS) alone and in combination with diphenyl guanidine (DPG). In the CBS accelerated system, incorporation of an optimum concentration of about 15% of ENR on total rubber was found to improve technological properties. Addition of a secondary accelerator further improves these properties. Comparable results are obtained with those containing coupling agent and NBR–ISAF. High bound rubber and volume fraction values indicate a high polymer–filler interaction and gel content resulting from the NBR–ENR interaction. Results of this study reveal that ENR could be used as a reinforcement modifier for the NBR–silica system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 292–306, 2002     

热裂解气相色谱法测定天然胶乳中的干胶含量

研究热裂解气相色谱法测定天然胶乳中的干胶含量。试验结果表明,干胶含量与裂解主要产物峰面积呈现良好的线性关系,采用标准曲线法测定天然胶乳中的干胶含量,重复测定的相对标准偏差为0.14%,与国标法的平均相对误差为1.51%,定量分析结果准确,操作简便。     

Studies on the adhesives for rubber to rubber bonding

Novel adhesive compounds for bonding natural rubber vulcanizates and NR/BR (natural rubber/polybutadiene) blend vulcanizates were developed. It has been shown that reclaimed latex waste can replace natural rubber in the adhesive, either partially or fully. The adhesives were found to retain their bond strength even after 5 weeks of aging at 30°C.     

高硬度橡胶-金属黏接体的黏结性能

采用热硫化黏接工艺制备了天然橡胶(NR)/溶聚丁苯橡胶(SSBR)-圆形金属黏接体,考察了硫化体系、增强体系对NR/SSBR-圆形金属黏接体界面黏结性能的影响。结果表明,高填充量炭黑增强NR/SSBR与圆形金属界面的最低黏接强度明显低于低填充量炭黑增强NR/SSBR;增加促进剂NOBS用量降低了橡胶与圆形金属界面的最低黏接强度;用3份预处理短纤维代替15~20份炭黑,不仅保持了被黏橡胶的邵尔A硬度及拉伸强度,而且明显改善了与圆形金属的黏结稳定性。     

Characterization of epoxidized natural rubber by 2D NMR spectroscopy

Assignment of signals in aliphatic region of ¹H NMR spectrum for epoxidized natural rubber was carried out through NMR spectroscopy. The epoxidized natural rubber was prepared by epoxidation of purified natural rubber with peracetic acid in latex stage followed by degradation with propanal and ammonium persulfate. The resulting liquid epoxidized natural rubber was characterized through 1D- and 2D-NMR spectroscopy. The unknown signals in the aliphatic region of the ¹H NMR spectrum were assigned through ¹³C NMR and two-dimensional heteronuclear shift correlation (HETCOR) measurement. The assignments were proved by two-dimensional inverse detected heteronuclear long-range shift correlation (HMBC) and two-dimensional homonuclear shift correlation (COSY) measurements, and they were supported with epoxidized squalene as a model compound through NMR spectroscopy.     

氟橡胶与金属黏接的研究进展

介绍了氟橡胶与金属的黏接机理,综述了氟橡胶与金属黏接用硅烷偶联剂、有机硅胶黏剂和含增黏组分胶浆的研究进展状况,指出简便实用、效果良好的黏接工艺是今后的发展方向。     

用附着型促进剂制备橡胶/蒙脱土纳米复合材料

用附着型促进剂PBS在机械混炼插层法的基础上制备了天然橡胶/蒙脱土纳米复合材料。由于硫化后大部分促进剂基团都连在橡胶分子链上,因此用分子一端能和蒙脱土片层有相互作用的附着型硫化促进剂,可以大大增强蒙脱土和橡胶基体的相互作用,得到性能优良纳米复合材料。用PBS制备纳米复合材料其硫化体系活性能低,硫化胶交联密度增大,有机蒙脱土片层在橡胶基体中达到纳米级的分散,具有优良的力学性能,加入8%有机蒙脱土100%模量从1.2 MPa增至2.2 MPa,500%模量从8.12 MPa增至18.23 MPa,邵氏GA硬度从45增至55,而加入2%有机蒙脱土500%模量从8.12 MPa增至17.06 MPa,撕裂强度从36.31 kN/m增至43.65kN/m,加入2~10份有机蒙脱土时其效果相当于加入40份半补强炭黑。     

Imidazole-promoted acceleration of crosslinking in epoxidized natural rubber/dicarboxylic acid blends

The crosslinking of epoxidized natural rubber (ENR) with dodecanedioic acid was tremendously accelerated in presence of 1,2-dimethylimidazole (DMI). The curing reaction of ENR containing 10 or 25 mol % epoxide groups was followed by rheology at 180 °C or 160 °C and the mechanical properties of the cured materials were examined by stress-strain experiments. An equimolar amount of accelerator and carboxylic functions was required to reach optimum tensile properties. Among a variety of usual accelerators, DMI was found the only one efficient, which was associated to the formation of reactive imidazolium carboxylates. The presence of these intermediates was supported by DSC experiments. Instead of a catalytic mechanism, the activation of the crosslinking agent is enabled by the synergetic association of DMI and diacid forming a soluble species in the rubber matrix. This simple system thus enables the efficient crosslinking of functionalized natural rubber without the use of sulphur or peroxides.     

HEMA接枝改性天然胶乳的制备及其粘接性能研究

以甲基丙烯酸羟乙酯(HEMA)作为天然胶乳(NRL)的接枝改性剂,采用乳液聚合法制备了NR-g-HEMA[HEMA接枝NR(天然橡胶)]胶乳;然后以此为基体,并以水溶性松香树脂为增黏树脂、邻苯二甲酸二丁酯(DBP)为增塑剂等,制备相应的NR-g-HEMA胶粘剂;最后,用该胶粘剂压制胶合板,并对胶合板的粘接性能进行了测定。结果表明:采用单因素试验法优选出制备NR-g-HEMA胶乳的最佳工艺条件为m(干态单体)∶m(NRL)∶m(引发剂)∶m(活化剂)∶m(交联剂)=20∶100∶0.2∶0.2∶0.1、反应时间为8 h和反应温度为16℃,此时相应胶合板的剪切强度(1.88 MPa)符合Ⅲ类胶合板的指标要求。     

A reactive acrylic adhesive for bonding polyolefins

An acrylic adhesive was developed for forming strong, water resistant structural joints with polyolefins. This two-component, lightly crosslinked, methyl methacrylate (MMA) based adhesive consisted of an anaerobic curing system in one part with a copper (II) salt catalyst in the other. Bonds formed with low density polyethylene (LDPE) resulted in substrate failure upon block shear testing throughout the open time of the adhesive (45 min). The interdiffusion of the monomers into the substrates, and their subsequent polymerization was followed using several infrared spectroscopy (IR) techniques. The interphase of mixed LDPE and adhesive was determined to be as thick as 1.7 mm using IR microscopy. It was concluded that the strong adhesion in the aforementioned joints was the result of the interpenetration of the adhesive into the substrates.     

粘接型CR244粉末橡胶在溶剂型氯丁粘合剂中的应用研究

研究了包覆凝聚法制备CR244粉末橡胶中,高分子树脂包覆剂组分、用量及2402树脂对所制备胶粘剂粘接性能的影响,同时对CR244粉末胶及片胶的溶解时间进行了比较。结果表明,M1、M2可提高胶粘剂的粘接强度;M3则会对粘接性能起到破坏作用。用包覆凝聚法制备的CR244粉末橡胶制备胶粘剂时仍可加入2402树脂,但用量应相对降低。用粉末胶代替传统片胶可大大缩短胶料溶解的时间,从而达到节能增效的目的。     

The Effect of Silica on the Peel Adhesion of Epoxidized Natural Rubber-Based Adhesive Containing Coumarone-Indene Resin

The peel strength of silica filled on two grades of epoxidized natural rubber (ENR), i.e., ENR 25 and ENR 50 adhesive were investigated using coumarone-indene as the tackifying resin. Toluene was used as the solvent throughout the study. Result shows that peel strength increases with increase in silica loading due to the concentration effect of the filler. Peel strength, however, shows maximum value at 40 phr silica for both ENR 25 and ENR 50 an observation that is attributed to the maximum wettability and compatibility of adhesive on the substrate.     

乙丙橡胶与金属粘接的研究进展

综述了乙丙橡胶与金属粘接的研究进展,介绍了乙丙橡胶与金属粘接的常用方法、几类常用的胶粘剂和提高两者粘接性能的措施。     

室温硫化硅橡胶胶粘剂的增强方法

通过硅橡胶丙烯酸(酯)改性、自制偶联剂、选择活性高分子材料、改善填料在胶粘剂中的分散性等方法，较好地提高了双组份室温硫化硅橡胶的粘接强度。     

Atomic force microscopy investigation of phase morphology correlated with adhesive properties for modified telechelic natural rubber based-pressure sensitive adhesive

Atomic force microscopy (AFM) is a powerful technique to determine phase morphology and surface mechanical properties of materials. In this research natural rubber was degraded and grafted by malelic anhydride before modification with 3-amino-1,2,4-triazole to obtain modified telechelic natural rubber or modified TNR. It was then blended with cumarone-indene resin at 10, 30, and 50 phr, acting as tackifier. Phase morphology and surface topography were investigated by intermitted AFM. The results showed that tackifier enriched domains were clearly observed in modified TNR matrix after added 30 and 50 phr and the domain sizes were approximately to be the order of micrometer (5–10 µm) which it increased with increasing tackifier content. The intermolecular hydrogen bonding interaction between tackifier and modified TNR was observed by attenuated total reflectance Fourier transform infrared spectroscopy. The adhesive properties (loop tack, peel, and shear strength) were governed by the size of tackifier enriched domains, surface mean roughness and compatibility or interaction between modified TNR rubber and cumarone-indene tackifier resin.     

Organomodified kaolin as a reinforcing filler for natural rubber

China clay (kaolin) has been modified with sodium salt of rubber seed oil (SRSO). SRSO was characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), and differential thermal analysis (DTA). XRD of the unmodified and SRSO‐modified kaolins showed an increase in the d‐(001) spacing of kaolin platelets from 7.15 to 14 Å. FTIR spectroscopy indicated possible grafting of the organic moiety of rubber seed oil (RSO) onto the clay surface. DTA of the SRSO‐modified kaolin indicated that the SRSO is more strongly bound in a constraint environment within the lamellae of kaolin. Natural rubber (NR) mix containing 10 phr of SRSO‐modified kaolin was found to cure faster than that of a similar mix containing unmodified kaolin. NR vulcanizates containing SRSO‐modified kaolin showed considerable increase in tensile modulus, tensile strength, and elongation at break indicating its potential as an organomodified nanofiller. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

橡胶金属粘合剂耐热性能研究

本文研究了不同种类的粘合剂在100℃至150℃温度下,预固化5分钟至15分钟对于天然橡胶金属复合件的粘合强度的影响。结果表明：预涂在金属表面的粘合剂经过适当的预固化处理后,对于成品取得高强度粘接性能是有帮助的。最佳的预固化温度不宜高于120摄氏度,时间不超过10分钟。     

Melt compounded epoxidized natural rubber/layered silicate nanocomposites: structure-properties relationships

Epoxidized natural rubber (ENR)-layered silicate composites were produced by melt compounding and sulfur curing. Pristine (sodium bentonite and sodium fluorohectorite) and organophilic modified silicates (organoclays with primary amine and quaternary ammonium modifications) were introduced in 10 parts per hundred rubber (phr) in the recipes and their effect on the curing and (thermo)mechanical properties determined. The dispersion state of the silicates was studied by X-ray diffraction and transmission electron microscopy. Fastest curing and best mechanical properties were found for the ENR containing the organoclay with primary amine modification. This organoclay was partly exfoliated, partly intercalated and partly confined (reaggregated). Due to the high shearing during compounding the pristine fluorohectorite was also intercalated by ENR. The complex dispersion state of the layered silicates was well reflected in the glass transition relaxation, which showed multiple peaks. Intercalation/exfoliation of the silicates were best displayed in stiffness- and strength-related mechanical parameters.