Properties of carbon fiber and composites modified with different‐sized graphene oxide sheets

The graphene oxide (GO) sheets with different size distributions were effectively separated by a centrifugation method. The exfoliated single‐layer structure and the size of GO sheets were verified by scanning electron microscopy (SEM), atomic force microscope (AFM), and metallurgical microscope, respectively. Two different‐sized GO sheets water suspensions were obtained, which were then directly dispersed in carbon fiber (CF) sizing agent, respectively. The influences of the different‐sized GO sheets on CF and CF composites were explored. The workability in later process of CF and CF surface morphology were characterized by abrasion resistance, fluffs and breakage, stiffness, and SEM. SEM micrographs demonstrated that a nonuniform distribution of the large‐sized GO was lapped on CF whereas the small‐sized GO was uniformly leaned on CF. The interlaminar shear strength of the small‐sized GO/CF reinforced composite could reaches the maximum value. It indicated that the interfacial region between CF and polymer matrix could be enhanced by adjusting the size of GO sheets. POLYM. COMPOS., 37:2719–2726, 2016. © 2015 Society of Plastics Engineers     

Chemically modified starch reinforced natural rubber composites

Chemically modified starch paste (MST) with polybutylacrylate (PBA) graft chains is investigated as a reinforcing filler of rubber through mixing and co-coagulating with natural rubber (NR) latex. The PBA graft chains are designed to prevent hydrogen bonding and crystallization of starch and to improve compatibility between starch and rubber. Through the comparison of mechanical properties and phase morphology, MST is proved to be much superior to unmodified starch paste. Unmodified starch paste acts as essentially inert filler causing a decrease of tensile strength, tear strength and elongation at break. In contrast, optimum MST shows obvious reinforcement effect on NR matrix by increasing tensile strength, elongation at break and tear strength besides modulus and hardness. Moreover, fine starch dispersion and strong interfacial interaction are achieved in NR/MST composites. The observed reinforcement effect is interpreted based on the results of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscope (SEM) analyses of grafted starch in comparison with natural starch and gelatinized starch.     

Simultaneous reduction and surface functionalization of graphene oxide and the application for rubber composites

The simultaneous reduction and functionalization of graphene oxide (GO) was realized through a chemical grafting reaction with a functionalization agent N,N-bis(3-aminopropyl)methylamine (APMEL). The reduced and functionalized reduced GO (rGO-APMEL) sheets can be well dispersed in water without any added surfactant and the formed stable rGO aqueous dispersion can be kept for a long time, which can be used for the preparation of rubber–graphene (GE) composites by latex mixing. The electrostatic interaction between rGO–APMEL (positively charged) and natural rubber latex particles (negatively charged) leads to the formation of NR/rGO–APMEL composites with strong interaction. Compared with blank NR, the tensile strength and modulus for NR/rGO–APMEL increase with the rGO–APMEL loading. Especially, when the filler content is 5 phr, the tensile strength of NR/rGO–APMEL-5 increases by 32.7%, as a control the tensile strength of NR/GO-5 and NR/rGO-5 decrease by 20.1 and 15.6%, respectively. The entanglement-bound rubber tube model was used to analyze the reinforcing effect of GE on NR/rGO–APMEL nanocomposites at a molecular level. This study may provide us a novel approach to prepare well dispersed and exfoliated rGO–polymer nanocomposites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47375.     

Preparation and properties of octadecylamine modified graphene oxide/styrene‐butadiene rubber composites through an improved melt compounding method

Octadecylamine modified graphene oxide/styrene‐butadiene rubber (GO‐ODA/SBR) composites are prepared by a novel and environmental‐friendly method called “Improved melt compounding”. A GO‐ODA/ethanol paste mixture is prepared firstly, and then blended with SBR by melt compounding. GO‐ODA sheets are uniformly dispersed in SBR as confirmed by scanning electron microscope, transmission electron microscopy, and X‐ray diffraction. The interfacial interaction between GO‐ODA and SBR is weaker than that between GO and SBR, which is proved by equilibrium swelling test and dynamic mechanical analysis. GO‐ODA/SBR show more pronounced “Payne effect” than GO/SBR composites, indicating enhanced filler networks resulted from the modification of GO with ODA. GO‐ODA/SBR composite has higher tensile strength and elongation at break than SBR and GO/SBR composite. The tensile strength and elongation at break for the composite with 5 parts GO‐ODA per hundred parts of rubber increase by 208% and 172% versus neat SBR, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42907.     

The reinforcing mechanism study of carbon nanotube in the NR matrix

The reinforcement mechanism of CNT in rubber matrix is an important and interesting subject. In this paper, carboxyled multi-walled carbon nanotubes (CNT) were used to prepare natural rubber (NR) nanocomposites (CNT/NR). CNT/NR composites were formed by mechanical blending method and the properties such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied. The results of Mechanical property show that the physical property of NR filled with 9 phr CNT (CNT/NR-9) is similar to that with 30 phr carbon black (CB) (CB/NR-30). In addition, the dispersion and interaction between CNT and NR were also studied by scanning electron microscope, transmission electron microscope, dynamic mechanical testing system and bound-rubber analysis. According to the results, CNT is considered to exhibit random orientations and form “string bag” structure in rubber matrix and the reinforcement mechanism of CNT is different to that of CB.     

两种橡胶/有机累托石纳米复合材料的结构与性能

比较了用熔体法制备的有机累托石(OR)/丁苯橡胶(SBR)以及有机累托石(OR)/天然橡胶(NR)2种纳米复合材料的结构与性能.TEM和XRD对材料的分析显示,由于橡胶基体的性质差异,OR/SBR为典型的插层型结构,而OR/NR为插层型和部分剥离型混合结构.应力应变行为的研究表明,随着OR用量的增加,OR/SBR的拉伸强度和拉断伸长率均增大,这主要是分子链滑移和填料的取向造成的.对于拉伸结晶型橡胶NR,由于部分剥离型填料的增强作用,NR的定伸应力随填料用量的增加而逐渐提高.由于对结晶的阻碍作用,当OR用量为20份时,OR/NR的拉伸强度有所降低.纳米累托石的加入可以显著提高SBR和NR的硬度和撕裂强度.热失重分析表明,OR/橡胶纳米复合材料与相应的纯橡胶相比,热稳定性提高,在NR体系中更为显著.     

Molecular-level dispersion of graphene into epoxidized natural rubber: Morphology,interfacial interaction and mechanical reinforcement

The interfacial interaction of composites dominates the properties of polymeric/inorganic nanocomposites. Herein, epoxy and hydroxyl groups are introduced into the natural rubber (NR) molecular chains to anchor oxygenous functional groups on the surface of graphene oxide (GO) sheets and therefore enhance the interfacial interaction between GO and rubber. From the morphological observation and interaction analysis, it is found that epoxidized natural rubber (ENR) latex particles are assembled onto the surfaces of GO sheets by employing hydrogen bonding interaction as driving force. This self-assembly depresses restacking and agglomeration of GO sheets and leads to homogenous dispersion of GO within ENR matrix. The formation of hydrogen bonding interface between ENR and GO demonstrates a significant reinforcement for the ENR host. Compared with those of pure ENR, the composite with 0.7 wt% GO loading receives 87% increase in tensile strength and 8.7 fold increase in modulus at 200% elongation after static in-situ vulcanization.     

Effects of Filler Loading and Different Preparation Methods on Properties of Cassava Starch/Natural Rubber Composites

Cassava starch-filled natural rubber (NR) composites were prepared by using direct blending and co-coagulation method. The effects of two different method and cassava starch loading on morphology, mechanical properties and thermal properties of cassava starch/NR composites were studied. X-ray diffraction results and scanning electron microscopy images proved that co-coagulation method promotes better dispersion of cassava starch than direct blending method. The composites prepared by co-coagulation method exhibited higher values of tensile strength, tear strength, hardness, and thermal stability. The optimum value of tensile strength and tear strength of cassava starch/NR composites were achieved at a 10 phr cassava starch loading.     

功能化还原氧化石墨烯/天然橡胶导热复合材料的性能研究

采用2-巯基苯并咪唑(防老剂MB,以下简称MB)对氧化石墨烯(GO)进行还原及功能化,同时与采用抗坏血酸(VC)对GO进行还原对比,分别制得MB还原氧化石墨烯(rGO-MB)和VC还原氧化石墨烯(rGO-VC),并采用胶乳共混法制备rGO-MB/NR和rGO-VC/NR复合材料,对其性能进行研究。结果表明:MB成功还原了GO,MB接枝到了GO上;与rGO-VC/NR复合材料相比,rGO-MB/NR复合材料具有较低的Payne效应和较高的结合胶含量,拉伸强度和导热性能均明显提高。     

改性纳米贝壳粉对天然橡胶复合材料力学性能的影响

采用钛酸酯对纳米贝壳粉(SP)进行了表面改性,并制备了改性纳米贝壳粉;通过与天然胶乳共混,制备了天然橡胶/贝壳粉(NR/SP)纳米复合材料;使用傅里叶红外光谱仪、扫描电子显微镜、表面接触角测定仪、XRD衍射分析仪、激光粒度仪和电子拉力试验机等研究了改性纳米贝壳粉对天然橡胶纳米复合材料力学性能的影响。结果表明,改性剂钛酸酯成功地偶联到贝壳粉表面,经过表面化学改性后贝壳粉表面接触角由73.5°增大到110.8°;当纳米贝壳粉用量为10%时,NR/SP复合材料可获得最佳力学性能,拉伸强度可达到34.05MPa。     

纳米氧化锌/二氧化硅杂化体的制备及其对天然橡胶复合材料性能的影响

采用3-氰基丙基三乙氧基硅烷（CTOS）对二氧化硅（SiO₂）进行了氰基化改性，并采用热溶剂法将纳米ZnO沉积于氰基官能化SiO₂（SiO₂-CN）表面，制备出纳米氧化锌/二氧化硅杂化体（ZnO@SiO₂），并使用X射线衍射仪、傅里叶变换红外光谱仪、扫描电镜等对杂化结构进行表征。将ZnO@SiO₂作为填料添加入天然橡胶中制备复合材料（NR/ZnO@SiO₂），然后对ZnO@SiO₂与橡胶的界面关系进行了分析，并研究了ZnO@SiO₂对橡胶复合材料的硫化特性、力学性能的影响。结果表明，纳米ZnO成功沉积在SiO₂-CN表面，并且NR/ZnO@SiO₂复合材料表现出优异的机械性能和硫化特性。与天然橡胶相比，仅添加5份杂化体的NR/ZnO@SiO₂复合材料的拉伸强度、100%定伸及300%定伸强度分别增加了150.2%、86.2%和65.5%，并且正硫化时间缩短了38.5%。     

有机蒙脱土对三元共混胎面胶（NR／BR／SBR）结构与性能的影响

采用机械共混法制备了天然橡胶（NR）／顺丁橡胶（BR）／丁苯橡胶（sBR）／有机蒙脱土（OMMT）复合材料;用X射线衍射（xRD）和扫描电镜（SEM）对复合材料的结构进行了表征,并研究了OMMT对复合材料的物理机械性能、硫化性能、热稳定性能的影响。结果表明,该复合材料为插层型复合材料,添加5phrOMMT有利于提高复合材料力学性能、耐磨性能、热稳定性能,促进硫化,降低最低扭矩。     

一段混炼时间对石墨烯/天然橡胶/溶聚丁苯橡胶复合材料性能的影响

采用一段密炼和二段开炼的两段混炼工艺制备氧化石墨烯(GO)/天然橡胶(NR)/溶聚丁苯橡胶(SSBR)和还原氧化石墨烯(rGO)/NR/SBR复合材料,研究一段混炼时间对GO/NR/SSBR和rGO/NR/SSBR复合材料性能的影响。结果表明:随着一段混炼时间的延长,GO/NR/SSBR和rGO/NR/SSBR复合材料的Fmax和FL增大,t90缩短;邵尔A型硬度、300%定伸应力、拉伸强度和撕裂强度呈先增大后减小的趋势,导电性能和导热性能呈先提高后降低的趋势,气密性能呈先提高后平稳再降低的趋势。     

氧化石墨烯/天然橡胶复合材料的制备与性能

采用己内酰胺（CPL）改性氧化石墨烯（GO）（CPL-GO）,与天然橡胶（NR）复合后通过熔融共混法制备了CPL-GO/NR复合材料。考察了CPL-GO用量对CPL-GO/NR复合材料物理机械性能、界面相互作用和气体阻隔性能的影响。结果表明,CPL改性GO后,X射线衍射层间距增加,片层堆砌更为松散,CPL-GO与水接触角增至91.2°。当CPL-GO的质量分数为2.0%时,CPL-GO/NR复合材料的拉伸强度为26.1 MPa,较纯NR提高了50.9%。随着CPL-GO用量的增加,复合材料的储能模量增加,损耗因子的峰值减小,表明GO经CPL表面改性后与NR复合,增强了两相界面间的相互作用,从而提高了复合材料抵抗变形的能力。在40 ℃下,当CPL-GO的质量分数为3.0%时,CPL-GO/NR复合材料的气体渗透系数较纯NR下降了57.1%。     

Effect of flake size on thermal properties of graphene oxide/poly(methyl methacrylate) composites prepared via in situ polymerization

The effect of graphene oxide (GO) flake size on thermal properties of GO/poly(methyl methacrylate) (GO/PMMA) composites prepared via in situ polymerization was investigated. Two styles of GO sheets were synthesized from different sizes of graphite powders by modified Hummers' method and GO/PMMA composites with GO of different sizes were prepared via in situ polymerization. Transmission electron microscopy verified that GO sheets produced from large graphite powders was obviously larger than that from small graphite powders. The similar number of layers and disorder degree of two types of GO sheets were proved by X‐ray diffraction and Raman, respectively. X‐ray diffraction and scanning electron microscopy results of GO/composites proved the homogenous dispersion of both two types of GO sheets in polymer matrix. Dynamic mechanical analysis and thermogravimetric analysis results showed that large GO sheets exhibit better improvement than small GO sheets in thermal properties of the composites. Compared with neat PMMA, the glass transition temperature and decomposition temperature of the composites with large GO sheets (0.20 wt %) were increased by 15.9 and 25.9 °C, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46290.     

混炼方式对螺旋纳米碳纤维增强天然橡胶复合材料力学性能的影响

采用干法和湿法两种混炼工艺制备了螺旋纳米碳纤维(HCNFs)/炭黑(CB)/天然橡胶(NR)复合材料,通过扫描电镜、拉伸试验机和应变扫描仪分别对所制备复合材料的界面形貌、力学性能和Payne效应进行了测试分析,考察了混炼方式对复合材料宏观力学性能及Payne效应的影响。结果表明,与纯CB填料相比,在干湿两种混炼方式下,添加适量的HCNFs(1～6份)能提高HCNFs/CB/NR复合材料的300%定伸应力、扯断伸长率、拉伸强度和硬度。与干法混炼相比,湿法混炼能明显增强HCNFs/CB/NR复合材料的Payne效应,并提升在HCNFs高添加量(2～6份)条件下的拉伸强度和扯断伸长率,这主要源于湿法混炼能够有效改善HCNFs在橡胶基质中的分散性。     

低共熔溶剂与偶联剂协同改性白炭黑对胎面胶性能的影响

研究了硅烷偶联剂(TESPT)与低共熔溶剂(DES)协同改性白炭黑对作为胎面胶的天然橡胶复合材料性能的影响.用傅里叶变换红外光谱分析了 TESPT和DES与白炭黑之间的相互作用,用橡胶加工分析仪和扫描电镜分析了白炭黑之间的相互作用,并测试了复合材料的硫化特性、力学性能和耐磨性,通过动态力学分析仪考察了其滚动阻力和抗湿滑...     

Mechanical properties of carbon fiber composites modified with graphene oxide in the interphase

The surface topographies of carbon fibers treated by sizing agents with different graphene oxide (GO) content were investigated by scanning electron microscopy. The surface elements compositions of carbon fibers were determined by X‐ray photoelectron spectrometer. The interfacial properties of composites were studied by interfacial shear strength. The thermo‐mechanical properties of two typical specimens (CF‐G0 and CF‐G1 composites) were investigated by dynamic mechanical thermal analysis. The results showed the introduction of GO sheets on carbon fibers surfaces effectively improved the mechanical properties of carbon fibers/epoxy composites. POLYM. COMPOS., 38:2425–2432, 2017. © 2016 Society of Plastics Engineers     

Effects of substitution for carbon black with graphene oxide or graphene on the morphology and performance of natural rubber/carbon black composites

In this study, nanosheets including graphene oxide (GO) and reduced graphene oxide (rGO), were incorporated into natural rubber (NR), to study the effects of substituting GO or rGO for carbon black (CB) on the structure and performance of NR/CB composites. The morphological observations revealed the dispersion of CB was improved by partially substituting nanosheets for CB. The improvements in static and dynamic mechanical properties were achieved at small substitution content of GO or rGO nanosheets. With substitution of rGO nanosheets, significant improvement in flex cracking resistance was achieved. NR/CB/rGO (NRG) composites has a much lower heat build‐up value compared with NR/CB/GO (NG) composites at a high load of nanosheets. However, both GO and rGO tended to aggregate at a high concentration, which led to the poor efficiency on enhancing the dynamic properties, or even deteriorate the performance of rubber composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41832.     

Mechanical and functional properties of composites based on graphite and carboxylated acrylonitrile butadiene rubber

In this study, carboxylated acrylonitrile butadiene rubber (xNBR)/expanded graphite (EG) nanocomposites were prepared with a latex compounding technique by ultrasonic stirring. The dispersion of EG in the xNBR matrix was investigated with transmission electron microscopy, scanning electron microscopy, and X‐ray diffraction analysis. EG could be exfoliated into lots of nanosheets dispersing in the xNBR matrix. More EG loading resulted in the presence of a few incompletely exfoliated agglomerates. The mechanical properties (hardness, tensile modulus, and tensile strength) of the xNBR/EG composites were determined. Dynamic mechanical thermal analysis was also performed, and it showed that the nanosheets of EG somewhat immobilized the motion of rubber macromolecular chains and led to the shifting and broadening of the tan δ peak toward higher temperatures. Many other functional properties of EG‐filled xNBR composites were studied, and it was established that the composites had excellent electrical conductivity as well as gas‐barrier and wear properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010