改性二氧化硅/NR纳米复合材料结构与性能研究

采用聚二甲基二烯丙基氯化铵(PDDA)对二氧化硅进行表面改性,制备改性二氧化硅/NR纳米复合材料,并对其微观结构和物理性能进行研究.结果表明,改性二氧化硅均匀分散在天然胶乳基体中;扫描电子显微镜分析显示复合材料呈界面模糊的海岛结构;改性二氧化硅/NR纳米复合材料的物理性能较NR胶料大幅提高;随着改性二氧化硅用量的增大,改性二氧化硅/NR纳米复合材料的物理性能先提高后降低;当改性二氧化硅的用量为5.3份时,纳米复合材料的综合物理性能较好.     

湿法混炼氧化石墨烯/天然橡胶复合材料的性能研究

采用湿法混炼工艺制备氧化石墨烯(GO)/天然橡胶(NR)复合材料,并对其性能进行研究。结果表明:加入GO的胶料门尼粘度增大,t_(10)和t_(90)延长,硫化胶的物理性能、导电性能和导热性能提高,储能模量增大,损耗因子减小;随着GO用量的增大,胶料的t_(10)和t_(90)先延长后缩短,硫化胶的定伸应力增大,拉伸强度和撕裂强度先增大后减小,导电性能变化不大,导热性能总体提高;当GO用量为2份时,复合材料的综合性能最佳,GO在复合材料中的分散性最好。     

改性石墨对天然橡胶复合材料导热性能的影响

研究表面活性剂或不同偶联剂对石墨改性效果以及石墨用量对天然橡胶(NR)复合材料物理性能、导热性能及微观结构的影响。结果表明:偶联剂Si69对石墨的改性效果最好,石墨呈现亲油性;与未改性石墨填充NR复合材料相比,偶联剂Si69改性石墨填充NR复合材料中石墨与NR间的界面相容性得到改善,物理性能和导热性能提高;随着偶联剂Si69改性石墨用量的增大,复合材料导热性能提高,物理性能先提高后下降。当改性石墨用量为30份时,复合材料的综合性能较好。     

环氧化杜仲橡胶在白炭黑/丁苯橡胶复合材料中的应用

研究环氧化杜仲橡胶(EEUG)在白炭黑/丁苯橡胶(SBR)复合材料中的应用。结果表明:在白炭黑/SBR复合材料中加入EEUG,混炼胶的门尼粘度增大,t_(10)和t_(90)缩短,Payne效应减弱;与白炭黑分散剂B-52和FS-79相比,EEUG改性的混炼胶加工性能略差,硫化胶的物理性能和耐磨性能更佳,压缩疲劳温升适中,剪切储能模量更大,损耗因子更小;3种助剂均能改善白炭黑在SBR中的分散性且效果相当。     

埃洛石纳米管/白炭黑并用补强NR的研究

研究埃洛石纳米管(HNTs)用量对NR/HNTs复合材料以及NR/HNTs/白炭黑复合材料性能的影响,试验结果表明,HNTs用量为40份时,NR/HNTs复合材料的综合物理性能较好;当HNTs/白炭黑/小分子氢键配体T的用量比为20/20/1时,NR/HNTs/白炭黑复合材料的物理性能、加工性能和热稳定性均较好.扫描电镜和透射电镜分析表明,HNTs和白炭黑均能在NR基体中均匀分散.     

硅藻土/白炭黑复合填料补强天然橡胶复合材料的性能研究

以硅藻土和白炭黑作为复合填料填充天然橡胶（NR）,研究硅藻土用量对硅藻土/白炭黑复合填料补强天然橡胶（DCNR）复合材料性能的影响。结果表明：随着硅藻土用量的增大,DCNR复合材料的t10和t90先增大后减小;硅藻土用量较小时,可提高DCNR复合材料的邵尔A型硬度;硅藻土用量过大,易产生明显的团聚,从而降低硅藻土/白炭黑复合填料对NR基体的补强效果,使得DCNR复合材料的综合物理性能下降。     

纳米氧化铝/天然橡胶复合材料的性能研究

采用原位改性纳米氧化铝制备纳米氧化铝/天然橡胶(NR)复合材料,研究纳米氧化铝用量及原位改性时间、偶联剂Si69用量对纳米氧化铝/NR复合材料的物理性能、动态力学性能和导热性能的影响。结果表明:随着纳米氧化铝用量的增大,复合材料的拉伸强度减小,热导率和压缩疲劳温升增大。原位改性可以提高纳米氧化铝与NR之间的界面结合作用。随着原位改性时间的延长或随着偶联剂Si69用量的增大,复合材料的拉伸强度和热导率均先增大后减小,压缩疲劳温升逐渐减小。     

环氧化天然橡胶对天然橡胶/炭黑复合材料的改性作用

采用环氧化天然橡胶(ENR)作为界面改性剂,研究其用量对天然橡胶(NR)/炭黑复合材料加工性能、动态力学性能和物理性能的影响。结果表明:少量ENR可以改善NR/炭黑复合材料的加工性能,改善炭黑粒子在橡胶基体中的分散,提高结合胶质量分数,同时改善硫化胶的动态力学性能、物理性能和耐老化性能。当改性剂ENR用量为3~4.5份时,NR/炭黑复合材料的综合性能最佳。橡胶加工分析和动态力学分析结果表明,ENR能够显著提高NR/炭黑复合材料的抗湿滑性能,但滚动阻力略有增大。     

芳纶短纤维增强天然橡胶复合材料性能研究

研究添加不同用量的芳纶短纤维/天然橡胶(NR)复合材料的性能。结果表明,NR复合材料的性能随着芳纶短纤维用量的增大先提高再下降;添加2份芳纶短纤维时复合材料的物理性能较好,磨耗性能也较优;添加芳纶短纤维能够使复合材料的抗湿滑性能变好,滚动阻力增大,导热性降低。     

二氧化钛/天然橡胶纳米复合材料的制备及性能研究

采用乳液共混法将纳米二氧化钛(TiO_(2))与天然胶乳直接混合,制备TiO_(2)/天然橡胶(NR)纳米复合材料,研究自然凝固、乙酸凝固、氯化钙凝固3种凝固方式和TiO_(2)用量对TiO_(2)/NR纳米复合材料性能的影响。结果表明:乙酸凝固制得的NR及TiO_(2)/NR纳米复合材料的综合性能最优;TiO_(2)的加入可有效提高NR复合材料的物理性能和耐老化性能;随着TiO_(2)用量的增大,TiO_(2)/NR纳米复合材料的物理性能明显提高,耐老化性能有一定程度提升。     

Synthesis,properties, and dyeing application of nonionic waterborne polyurethanes with different chain length of ethyldiamines as the chain extender

This study deals with the synthesis of some nonionic waterborne polyurethanes (PUs), using ethyldiamines of different chain length, such as ethylenediamine (EDA) and diethyltriamine (DETA), as the chain extender in the reaction, and examines the thermal properties, mechanical properties, and dyeing properties of the PU products and their blends. As far as each PU by itself is concerned, we found that the T_g of the one made with DETA is the highest, followed by that with EDA, and the one with 1,4‐butanediol (1,4‐BD) is the lowest. The PU made with 1,4‐BD as the chain extender has no T_m, while the two others, using diamines as chain extenders, have a clear T_m, the one with DETA being higher than that with EDA. However, the enthalpy data are just the opposite. The tensile strengths of the two PUs, made with diamines as the chain extender, are larger than that made with 1,4‐BD, but their respective elongation properties are just the opposite. A comparison within PUs made with diamines showed that the one made with EDA is greater in both strength and elongation categories than that made with DETA. However, the one made with DETA is far superior to both of those made with 1,4‐BD and EDA in their dye‐exhaustion ratio, color yield (K/S), fixation rate, and color fastness. In respect to the various PU mixtures that we examined, we found that both PUs synthesized with EDA or DETA as the chain extender would have their T_g's greatly increased by blending in some PU made using 1,4‐BD as the chain extender. Among them, in particular, a blend of PU, made separately with DETA and 1, 4‐BD as the chain extender, showed great improvements in both tensile strength and elongation and also demonstrated better dyeability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2824–2833, 2003     

TPI结晶性对DCP硫化TPI胶料性能的影响

研究了反式-1,4-聚异戊二烯（TPI）结晶性对不同用量过氧化二异丙苯（DCP）硫化的TPI性能的影响。结果表明,拉伸前后TPI试样的XRD曲线上结晶峰有明显不同。TPI预拉伸冷冻试样的拉伸性能与冷冻前后原始试样的差异明显。随着DCP用量的增加,500mm/min和50mm/min拉伸速率下测得的拉伸强度之间的差异变得越来越小;同一压缩率时,试样的压缩强度不断降低。在tanδ-温度曲线上,随着交联密度的提高,TPI低温损耗峰的tanδ值不断增大,而其高温损耗峰的tanδ值呈下降趋势。     

Effect of different nanoparticles on thermal,mechanical and dynamic mechanical properties of hydrogenated nitrile butadiene rubber nanocomposites

Organically modified and unmodified montmorillonite clays (Cloisite NA, Cloisite 30B and Cloisite 15A), sepiolite (Pangel B20) and nanosilica (Aerosil 300) were incorporated into hydrogenated nitrile rubber (HNBR) matrix by solution process in order to study the effect of these nanofillers on thermal, mechanical and dynamic mechanical properties of HNBR. It was found that on addition of only 4 phr of nanofiller to neat HNBR, the temperature at which maximum degradation took place (T_max) increased by 4 to 16°C, while the modulus at 100% elongation and the tensile strength were enhanced by almost 40–60% and 100–300% respectively, depending upon nature of the nanofiller. It was further observed that T_max was the highest in the case of nanosilica‐based nanocomposite with 4 phr of filler loading. The increment of storage modulus was highest for sepiolite‐HNBR and Cloisite 30B‐HNBR nanocomposites at 25°C, while the modulus at 100% elongation was found maximum for sepiolite‐HNBR nanocomposite at the same loading. A similar trend was observed in the case of another grade of HNBR having similar ACN content, but different diene level. The results were explained by x‐ray diffraction, transmission electron microscopy, and atomic force microscopy studies. The above results were further explained with the help of thermodynamics. Effect of different filler loadings (2, 4, 6, 8, and 16 phr) on the properties of HNBR nanocomposites was further investigated. Both thermal as well as mechanical properties were found to be highest at 8 phr of filler loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical,dielectric, and thermal properties of fluorosilicone rubber composites filled with silica/multiwall carbon nanotube hybrid fillers

In this work, hybrid fillers consist of modified silica (SiO₂) and multiwalled carbon nanotube (MWCNT) were used to improve the mechanical, dielectric, and thermal properties of fluorosilicone (FSR) composites via a direct mechanical mixing method. With the increase of CNT loading in SiO₂/CNT hybrid loading ratio, the tensile properties, dielectric constant, electrical conductivity, and thermal properties all increase without a sharp sacrifice of flexibility. The dielectric constant of FSR-S15/C5 achieved 7,370 @1 kHz, which is about four orders of the FSR-S20, and the dielectric loss remains as low as 0.676 @1 kHz. Therefore, the linkage of SiO₂ and FSR chains not only enhances the interfacial interaction between the fillers and FSR matrix but also decreases the agglomeration of the fillers in matrix. What is more, modified SiO₂ and CNT were designed as the effective hybrid filler to improve the performance of the polymeric matrix through synergic effect.     

The effect of fiber concentration on mechanical and thermal properties of fiber‐reinforced polypropylene composites

A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene‐co‐ethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP–PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) with reference to the fiber concentration. Although, by increasing PP fiber concentration in PPE, no significant difference was found in melting and crystallization temperatures of the PPE, the storage, and the tensile and flexural modulus of the composites increased linearly with fiber concentrations up to 50%, 1.5, 1.0, 1.3 GPa, respectively, which was approximately four times higher than that for the pure PPE. There is a shift in glass transition temperature of the composite with increasing fiber concentration in the composite and the damping peak became flatter, which indicates the effectiveness of fiber–matrix interaction. A higher concentration of long fibers (>50% w/w) resulted in fiber packing problems, difficulty in dispersion, and an increase in void content, which led to a reduction in modulus. Cox–Krenchel and Haplin–Tsai equations were used to predict tensile modulus of random fiber‐reinforced composites. A Cole–Cole analysis was performed to understand the phase behavior of the composites. A master curve was constructed based on time–temperature superposition (TTS) by using data over the temperature range from −50 to 90°C, which allowed for the prediction of very long and short time behavior of the composite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2260–2272, 2005     

Impact of compression molding conditions on the thermal and mechanical properties of polyethylene

Compression molding is a current technique in polymer processing. Despite numerous studies, effect of molding pressure on physical properties has surprisingly not been fully investigated. In this study, the thermal and mechanical behavior of the compression‐molded polyethylene were thus explored to better grasp the relationship between processing parameters and ensuing properties. The effect of the molding temperature, pressure, cooling rate, and temperature profile on the tensile and flexural moduli as well as melting point of polyethylene was studied. We conclude that higher tensile and flexural moduli are obtained by increasing pressure and molding temperature, as well as decreasing the cooling rate. Our results were corroborated by X‐ray diffraction and differential scanning calorimetry measurements. Moreover, the use of a temperature gradient with different temperatures for the upper and bottom plates of the mold leads to asymmetric samples whose tensile and flexural moduli are improved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46176.     

Effect of surface chemistry and morphology of silica on the thermal and mechanical properties of silicone elastomers

In this study, high‐temperature vulcanized silicone rubbers (HTV‐SRs) using fumed silica (FSi), precipitated silica (PSi), and modified precipitated silica (MPSi) as reinforcing fillers were prepared. The effect of morphology and surface chemistry of the silica on the thermal and mechanical properties of the resultant silicone rubbers was investigated using curing rheometer, scanning electron microscopy, mechanical test, and dynamic mechanical analysis. The thermo‐oxidative stability and solvent resistance of the vulcanized silicone rubbers were further evaluated via heat ageing test, extraction, and swelling experiments. It is shown that the mechanical properties (tensile modulus and tensile strength) of the as‐prepared HTV‐SRs are in the order of FSi > PSi > MPSi, which could be attributed to the molecular interaction between the filler and the matrix. FSi has the highest surface area, which enhances the hydrogen bonding interaction between the filler and the silicone matrix; while MPSi, in which part of Si? OH groups have been consumed during modification, shows the weakest interaction among the three. The filler–matrix interaction could also explain the lowest swelling and sol fraction in FSi‐filled HTV‐SR, and the low viscosity and good processibility of PSi‐ and MPSi‐filled HTV‐SR. Furthermore, it is also shown that the MPSi‐filled HTV‐SR exhibits the highest retention of mechanical properties after thermal aging at 250 °C for 24 h, which could be attributed to the lowest acidity of the fillers. The possible mechanism for acid catalyzed hydrolytic chain scission and intramolecular chain backbiting has been proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46646.     

The impact of polymer matrix blends on thermal and mechanical properties of boron nitride composites

To improve mechanical and thermal properties of a hexagonal boron nitride platelet filled polymer composites, maleic anhydride was studied as a coupling agent and compatibilizer. Injection molded blends of acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPE), and maleic anhydride with boron nitride filler were tested for thermal conductivity and impact strength to determine whether adding maleic anhydride improved interfacial interactions between matrix and filler and between the polymers. Adding both HDPE and maleic anhydride to ABS as the matrix of the composite resulted in a 40% improvement in impact strength without a decrease in thermal conductivity when compared to an ABS matrix. The best combination of thermal conductivity and impact strength was using pure HDPE as the matrix material. The effective medium theory model is used to help explain how strong filler alignment helps achieve high thermal conductivity, greater than 5 W/m K for 60 wt % boron nitride. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48661.     

Synthesis and characterization of polyurethane anionomers

Un‐ionized polyurethane was obtained by the reaction of an isocyanate‐terminated urethane prepolymer, which was synthesized from 4,4′‐diphenylmethane diisocyanate and poly(oxytetramethylene)‐α,ω‐glycol, with 2,2‐bis(hydroxymethyl)propionic acid. A carboxylate‐based polyurethane anionomer was then derived from the polyurethane by the use of the sodium, potassium, or magnesium salt of acetic acid as a neutralizer. The ionomerization resulted in the following changes in the characteristics of the polyurethane: (1) an increase in the tensile strength, (2) a decrease in the glass‐transition temperature, (3) an increase in the wettability and hygroscopicity with respect to water, and (4) susceptibility to thermal decomposition. A sulfonate‐based polyurethane was also synthesized for comparison with the carboxylate‐based polyurethane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2144–2148, 2005     

Effects of flame‐retardant flax‐fiber on enhancing performance of the rigid polyurethane foams

The original flax fibers (FF) and the modified FFs were subjected to the treatment with the flame retardant, were used to improve the performance of rigid polyurethane foams (RPUF). The mechanical properties of composites were evaluated by compressive strength test, torsion strength test, and shear stress test. The fire characteristics (smoke and heat production) were studied using cone calorimeter. And the thermal decomposition and flammable properties were further evaluated using thermogravimetric analysis and limiting oxygen index. The results showed that the FF could improve the mechanical properties of RPUF and had a good prospect in reducing the fire hazard for RPUF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46436.