The Fatigue Behaviour of Filled Epoxidized Natural Rubber Compounds

Abstract

The fatigue behaviour of white rice husk ash (WRHA) filled ENR-50 compounds was compared with those of silica (Vulcasil-S) and carbon black (N 330) filled compounds. The effect of WRHA loading on scorch time and Mooney viscosity was also studied. The incorporation of WRHA in ENR-50 compounds reduced the scorch time but increased the Mooney viscosity. The increment in filler loadings has resulted in the reduction of the fatigue fife. The fatigue behaviour of ENR-50 vulcanizates was observed to be strain dependent. At a similar filler loading, silica filled vulcanizates showed the highest fatigue life followed by those of WRHA and carbon black.     

环氧化天然橡胶在全钢子午线轮胎胎面配方中的应用

研究了环氧化天然橡胶(ENR-40)在全钢子午线轮胎胎面配方中的应用效果。试验表明,ENR-40部分取代NR应用到轮胎配方中具有一定的优异性,对胎面配方硫化特性影响不大,胎面胶配方的物理机械性能提高,压缩疲劳生热降低。     

咪唑促进双氰胺固化环氧树脂体系固化动力学

采用差示扫描量热(DSC)法研究了2-乙基-4-甲基咪唑(2E4MI)的含量对双氰胺(DICY)固化环氧树脂体系固化动力学的影响。非等温DSC测试结果表明,2E4MI能大幅度降低DICY固化环氧树脂所需要的温度和活化能,从而加快反应的进行。当2E4MI用量为0.2份时,活化能最低为84.2 kJ/mol且整体活化能随固化度的变化较小、固化更均匀。在2E4MI最佳用量(0.2份)下对固化体系进行等温DSC以及潜伏性测试,结果表明,该体系在160℃下20 min内可完成固化,室温储存15 d的固化度仅为0.146,说明其适合用作快速固化环氧树脂储存体系。     

橡胶加工分析仪研究环氧化天然橡胶的性能

用橡胶加工分析仪对环氧化天然橡胶进行了温度扫描、频率扫描和应变扫描，并和天然橡胶的响应曲线进行了对比。     

Curing Characteristics and Mechanical Properties of Oil Palm Wood Flour Reinforced Epoxidized Natural Rubber Composites

Abstract

The paper reports on the curing characteristics and mechanical properties of oil palm wood flour (OPWF) reinforced epoxidized natural rubber (ENR) composites. Three sizes of OPWF at different filler loadings were compounded with a two roll mill. The cure (t ₉₀) and scorch times of all filler size decrease with increasing OPWF loading. Increasing OPWF loading in ENR compound resulted in reduction of tensile strength and elongation at break but increased tensile modulus, tear strength and hardness. The composites filled with smaller OPWF size showed higher tensile strength, tensile modulus and tear strength. Scanning electron microscope (SEM) micrographs showed that at lower filler loading the fracture of composites occurred mainly due to the breakage of fibre with minimum pull-out of fibres from the matrix. However as the filler loading is increased, the fibre pull-out became very prominent due to the lack of adhesion between fibre and rubber matrix.     

环氧化天然橡胶及其应用研究进展

介绍环氧化天然橡胶(ENR)的制备方法、性能及其对聚合物基复合材料的改性效果.ENR在保留天然橡胶(NR)的结构和性能的基础上,可进一步提高NR的气密性能和耐油性能等.不同硫化体系硫化ENR的性能不同,ENR的环氧度越高,其玻璃化温度越高,气密性能和耐溶剂性能越好.ENR可作为相容剂对NR和其他橡胶及白炭黑进行改性,提高胶料的性能和白炭黑在胶料中的分散性.     

Biocomposites of Epoxidized Natural Rubber/Poly(lactic acid) Modified with Natural Fillers (Part I)

The study aimed to prepare sustainable and degradable elastic blends of epoxidized natural rubber (ENR) with poly(lactic acid) (PLA) that were reinforced with flax fiber (FF) and montmorillonite (MMT), simultaneously filling the gap in the literature regarding the PLA-containing polymer blends filled with natural additives. The performed study reveals that FF incorporation into ENR/PLA blend may cause a significant improvement in tensile strength from (10 ± 1) MPa for the reference material to (19 ± 2) MPa for the fibers-filled blend. Additionally, it was found that MMT employment in the role of the filler might contribute to ENR/PLA plasticization and considerably promote the blend elongation up to 600%. This proves the successful creation of the unique and eco-friendly PLA-containing polymer blend exhibiting high elasticity. Moreover, thanks to the performed accelerated thermo-oxidative and ultraviolet (UV) aging, it was established that MMT incorporation may delay the degradation of ENR/PLA blends under the abovementioned conditions. Additionally, mold tests revealed that plant-derived fiber addition might highly enhance the ENR/PLA blend’s biodeterioration potential enabling faster and more efficient growth of microorganisms. Therefore, materials presented in this research may become competitive and eco-friendly alternatives to commonly utilized petro-based polymeric products.     

脲衍生物对环氧树脂/双氰胺体系促进作用的研究

对比了不同结构的脲衍生物[3-(3-氯-4-甲基苯基)-1,1-二甲基脲(A)、3-(3,4-二氯苯基)-1,1-二甲基脲(B)、3-(4-氯苯基)-1,1-二甲基脲(C) ]对环氧树脂/双氰胺体系的促进作用。利用差示扫描量热仪和傅里叶变换红外光谱研究了3种环氧树脂/双氰胺/脲体系的反应活性和固化反应动力学。结果表明,体系A的最佳配比为：环氧：双氰胺：脲A=100：6：4（质量比,下同）,130 ℃时40 min就可以完全固化,其表观活化能（Ea）=64.66 kJ/mol,反应级数（n）=0.897;体系B的Ea=71.68 kJ/mol,n=0.930;体系C的Ea=71.03 kJ/mol,n=0.928;3种体系配制的胶液的室温剪切强度均大于20 MPa,体系A的粘接强度达到24.98 MPa。     

苯胺改性双氰胺固化剂的合成及性能研究

研究了苯胺改性双氰胺的合成工艺及其对环氧树脂固化性能的影响规律。苯胺改性双氰胺的最佳合成工艺条件为：浓盐酸和苯胺的摩尔比为1．1：1,双氰胺和苯胺的摩尔比为1．2：1,反应温度为90℃,反应时间为4h,产物收率可达88．35％。利用改性双氰胺固化环氧树脂制备涂层并测试其硬度,考察了固化剂与环氧树脂配比、固化温度和时间对涂层固化性能的影响规律。研究结果表明,最佳配比（质量比）为1：2．86,在130℃固化3．5h后,涂层硬度可达到1．39。与未改性双氰胺固化环氧树脂相比,其最低固化温度降低了30℃,且固化性能明显提高。     

环氧化天然橡胶复合材料性能研究

采用新方法制备环氧化天然橡胶(ENR)/白炭黑和天然橡胶(NR)/ENR/白炭黑复合材料,并对其性能进行研究。结果表明:ENR/白炭黑复合材料的热稳定性优于ENR;在NR/ENR并用胶中加入白炭黑和硅烷偶联剂KH-550,NR/ENR/白炭黑复合材料0℃时的损耗因子(tanδ)增大,65℃时的tanδ值减小,复合材料的抗湿滑性能提高,滚动阻力减小。     

白炭黑在环氧化天然橡胶中的应用

摘要：研究在不使用任何偶联剂的条件下,白炭黑在环氧化天然橡胶（ENR）中的应用。白炭黑在天然橡胶（NR）中会发生明显的团聚,而在ENR中的团聚情况可得到明显改善,且ENR的环氧化程度越高,白炭黑的分散性越好。ENR白炭黑胶料表现出良好的抗湿滑性能和较低的滚动阻力,白炭黑用量大T20份时,ENR/白炭黑胶料的压缩生热明显低于NR／炭黑胶料。     

Curing Characteristics and Aging Properties of Natural Rubber/Epoxidized Natural Rubber and Cellulose II

In this work, natural rubber (NR) and regenerated cellulose (cel II) latexes were co-coagulated and to the mixture epoxidized natural rubber (ENR) was added on a two-roll mill. The cellulose content was fixed at 20 phr while ENR content varied from 0 to 75 phr. The influence of ENR was studied through the cure characteristics, aging and dynamic-mechanical properties. The aging provides nanocomposites with better solvent resistance and increased tensile strength at ENR content of 25 phr. The results suggest that a new type of light-colored nanocomposites were obtained, which presented high mechanical performance and resistance to solvents.     

Curing Behavior of Epoxy Resin Using Controllable Curing Agents Based on Nickel Complexes

Summary: The curing reaction kinetics and mechanism of the diglycidyl ether of bisphenol A (DGEBA) with three complexes of Ni(II) with diethylentriamine (Dien), Pyrazole (Pz) and Pyridine (Py) as ligands have been studied using differential scanning calorimetry (DSC). The curing reaction was characterized by high cure onset and peak maximum temperatures. The kinetics of the curing reaction were evaluated using the Ozawa method. The average values of activation energy for the three nickel complexes increased in the order: Dien‐based curing agent > Pz‐based curing agent > Py‐based curing agent. Three main curing mechanisms (catalytic, complex cation and free ligand polymerization path) have been proposed depending on the cure temperature. It was also shown that the cure kinetics of DGEBA with Dien‐ and Py‐based complexes could be described by the Sestak‐Berggren equation. The water absorption, chemical resistance and thermal stability of the thermosets were also studied. The results showed that the thermoset obtained with the Py‐based complex was more thermally stable than those obtained with the other two curing agents.

Activation energy versus conversion plots for the epoxy systems studied.     

硅藻土/天然橡胶复合材料的性能研究

利用环氧化天然胶乳作为硅藻土的界面改性剂,制备了硅藻土/天然橡胶复合材料,通过无转子流变仪、电子万能材料试验机和橡胶动态压缩生热仪,研究了复合材料的硫化特性,物理机械性能和温升特性。结果表明,硅藻土/天然橡胶复合材料的焦烧与正硫化时间随着硅藻土含量的增加,先增后减;最大与最小扭矩随硅藻土含量的增加而增加;硅藻土/天然橡胶复合材料的拉伸与撕裂强度均有提高,当硅藻土含量为4phr时,拉伸强度最高,为28.5MPa;当硅藻土的含量为2phr时,撕裂强度最高,为37.9N/mm;由于硅藻土的加入,材料的内生热显著降低。     

对甲基苯胺改性双氰胺环氧固化剂的合成及性能

用对甲基苯胺对双氰胺进行改性,制备了一种新型的改性双氰胺固化剂,对合成条件进行了优化,并对其固化环氧树脂条件进行了研究。结果表明,对甲基苯胺改性双氰胺的较佳工艺条件为对甲苯胺和水的物质的量比定为1∶1.5,双氰胺和苯胺的物质的量比为1∶1,转速为一档,于90℃,反应3h,收率85%。通过测试涂层硬度来考察固化工艺与性能。作为环氧树脂固化剂单独使用时,固化温度为110℃,比双氰胺体系固化温度160℃降低了近50℃,对甲基苯胺改性双氰胺固化温度高于120℃时,涂膜硬度大于双氰胺固化温度为160℃时涂膜硬度。     

硬脂酸钙对ENR25硫化动力学的影响

采用流变仪测定添加不同硬脂酸钙用量的环氧化程度为25的环氧化天然橡胶(ENR25)的硫化曲线,研究硬脂酸钙用量对环氧化天然橡胶硫化动力学参数的影响。研究结果表明,随着硬脂酸钙用量的增加,反应速率常数k增大,硫化反应活化能E降低,表明硬脂酸钙的加入有助于促进ENR25的硫化,这可以减少生产过程中能耗,提高生产效率。     

聚醚酰亚胺/环氧树脂体系的固化及相分离行为研究

环氧树脂固化物本征的低韧性是限制其在复合材料应用的主要缺点之一。利用高性能热塑性树脂聚醚酰亚胺(PEI)与环氧树脂共混,系统研究了PEI在环氧树脂中的溶解行为、固化行为以及相分离行为。溶解试验表明:PEI与环氧齐聚物具有良好的相互溶解性;同时,PEI的加入降低了环氧树脂固化反应的活化能,但并没有改变其固化反应的机制。扫描电镜结果显示:随着PEI含量的增加,环氧/PEI浇铸体的相形貌从明显的分散颗粒相结构演变为双连续相结构和反转相结构。     

中温固化丁腈橡胶改性环氧树脂胶黏剂的研究

制备了四种环氧树脂(E-51、AG-80、AFG-90、TDE-85)及其复合树脂体系的液体丁腈橡胶CTBN改性胶黏剂,研究了这些胶黏剂及加入不同质量的TDE-85和AFG-90后的粘接性能。研究结果表明,TDE-85对改性胶的室温剪切和剥离强度贡献较大,AFG-90对高温剪切强度贡献较大。在TDE-85改性胶(TC-23)和TDE-85/E-51复合树脂改性胶(TEC-23)中,添加10%的AFG-90,可使它们的室温、100℃剪切及室温剥离强度分别达到37.4MPa、16.7MPa,65.4N·cm-1和33.7MPa、18.2MPa,60.0N·cm-1,具有较好的综合性能。     

端胺基聚氨酯/环氧树脂胶粘剂的固化反应特征及其反应动力学研究

采用差示扫描量热法(DSC)研究了含有柔性链和刚性结构单元的端胺基聚氨酯(ATPU)对环氧树脂E-44固化反应过程特点和反应过程动力学的影响。结果表明,固化剂(ATPU)的掺加量对环氧树脂E-44固化反应过程有显著的影响,随着ATPU的增加,固化放热量增加。当ATPU的掺加量为1.6时,固化反应放热量达到最大值。固化温度研究表明,ATPU/E-44固化体系的等温固化起始温度和最高温度分别为121℃和177℃。固化反应的动力学研究表明,ATPU/E-44胶粘剂固化反应的表观活化能为81.8kJ/mol;固化反应的级数为1.3。     

环氧豆油丙烯酸酯光固化速率的影响因素

将环氧大豆油与丙烯酸反应制备出环氧豆油丙烯酸酯预聚物,考察了光引发剂的种类、用量、辐射距离、时间及合成树脂的结构对光固化速率的影响,并利用红外光谱对树脂固化前后的结构进行了表征。研究结果表明,当辐射距离为20 cm时,光引发剂IHT-PI 184的用量为3%时固化速率最快,且随着酯化率的升高,固化速率加快,光固化后凝胶含量达到94.7%。