两种小分子有机酸修饰的白泥对丁腈橡胶复合材料力学性能的影响

利用草酸、乙酸作为白泥的修饰剂,对白泥进行湿法修饰,而后利用石蜡对白泥进行二次包覆制备了有机修饰白泥,并将其作为橡胶填料填充到丁腈橡胶(NBR)中制备了修饰白泥/NBR(300:100)母胶。将不同份数母胶填充到NBR中制备了不同白泥含量的白泥/NBR复合材料。考察了母胶用量,修饰剂种类及用量对NBR复合材料的硫化性能以及力学性能的影响。实验结果表明:当修饰剂的用量逐步增加(以干白泥质量计算)时,母胶填充的白泥/NBR复合材料的力学性能呈现先增大后减小的趋势。草酸用量为白泥的2%且母胶份数为75 phr时其白泥/NBR复合材料的力学性能达到较佳值:拉伸强度11.0MPa、扯断伸长率483%、300%定伸应力3.9 MPa,与硬脂酸用量为白泥2%且母胶份数为75 phr时其白泥/NBR复合材料的拉伸强度、扯断伸长率、300%定伸应力进行对比分别提高196%、155%、115%;乙酸用量为白泥的2%且母胶份数为75 phr时其白泥/NBR复合材料的力学性能达到最佳值:拉伸强度10.0MPa、扯断伸长率463%、300%定伸应力3.6 MPa,与硬脂酸用量为白泥2%且母胶份数为75 phr时其白泥/NBR复合材料的拉伸强度、扯断伸长率、300%定伸应力进行对比分别提高179%、150%、106%。样品断面扫描电镜(SEM)分析结果表明,白泥经有机修饰后在丁腈橡胶中分散均匀,与基体橡胶的相容性好。多项实验结果表明:利用草酸、乙酸修饰白泥并制备白泥橡胶母胶可作为白泥综合利用的一种有效方法。     

增粘树脂对间苯二酚-甲醛-胶乳体系浸渍连续玄武岩纤维帘线/橡胶粘合性能的影响

研究增粘树脂对间苯二酚-甲醛-胶乳(RFL)体系浸渍连续玄武岩纤维(CBF)帘线与橡胶基体粘合性能和界面疲劳性能的影响。结果表明,加入增粘树脂,橡胶基体的拉伸强度和定伸应力降低,拉断伸长率提高,橡胶与CBF帘线静态粘合性能的变化与间苯二酚/甲醛比例有关,RFL体系浸渍的CBF帘线与橡胶基体的界面疲劳寿命大幅延长。     

丁腈橡胶/芳纶短切纤维复合材料的制备及性能研究

采用高锰酸钾硫酸溶液对芳纶短切纤维表面进行改性处理,然后再与丁腈橡胶复合制备了丁腈橡胶/芳纶短切纤维复合材料。探讨了芳纶短切纤维表面不同处理时间对复合材料机械性能的影响。结果显示,当芳纶短切纤维表面处理时间为20 min时,复合材料的拉伸强度达到最大值;复合材料的扯断伸长率随纤维表面处理时间的增加呈上升趋势,但处理时间超过20 min后,扯断伸长率的变化趋于平缓;复合材料的撕裂强度和硬度随处理时间的增加变化不明显。     

硫化剂双酚AF和DCP对EPDM/FKM共混胶性能影响

研究了硫化剂双酚AF和DCP用量对EPDM/FKM共混胶硫化特性和热空气老化前后物理机械性能的影响。实验证明,随着双酚AF用量的增加,共混胶M_H变大,t_(10)基本不变,t_(90)变大;硬度和扯断伸长率基本不变,拉伸强度和100%定伸应力均变大;老化后,硬度和100%定伸应力变大,拉伸强度和扯断伸长率变小。随着DCP用量的增加,共混胶M_H变大,t_(10)基本不变,t_(90)变小;硬度基本不变,拉伸强度先上升后下降,100%定伸应力变大,扯断伸长率下降;老化后,硬度和100%定伸应力变大,拉伸强度和扯断伸长率均变小。     

酸性活性修饰剂对白泥/丁腈橡胶复合材料力学性能的影响

利用丙烯酸和对乙烯苯磺酸作为白泥的修饰剂,对白泥进行湿法修饰,而后利用石蜡对白泥进行二次包覆制备了有机修饰活性白泥,并将其作为橡胶填料填充到丁腈橡胶(NBR)中制备了修饰白泥/NBR(400:100)母胶,而后将母胶填充到NBR中制备了不同白泥含量的白泥/NBR复合材料。考察了不同修饰量制备的母胶对复合材料硫化性能的影响、母胶及用量对NBR复合材料的性能影响。实验结果表明:当加入修饰剂的用量逐步增加(以干白泥质量计算)时,母胶填充的白泥/NBR复合材料的力学性能呈现先增大后减小的趋势。酸性活性剂用量为白泥2%的母胶且母胶份数为100phr时其白泥/NBR复合材料的力学性能达到最佳值。但是两种活性修饰剂修饰的白泥母胶在改性NBR性能上存在差异:丙烯酸修饰白泥母胶制备的白泥/NBR复合材料的力学性能为拉伸强度8.3MPa、扯断伸长率386%、300%定伸应力3.7MPa、硬度79;乙烯苯磺酸修饰白泥母胶的力学性能为拉伸强度9.8MPa、扯断伸长率652%、300%定伸应力4.2MPa、硬度78。研究表明:利用丙烯酸、对乙烯苯磺酸作为白泥的修饰剂并制备橡胶母胶可大幅度提高橡胶材料的力学性能,可作为白泥综合利用的一种有效方法。     

芳纶纤维增强丁腈橡胶的摩擦性能

研究了芳纶纤维增强丁腈橡胶(NBR)复合材料的物理机械性能和摩擦性能,并用扫描电子显微镜分析了芳纶纤维增强NBR复合材料的磨损表面和磨屑形貌。结果表明,芳纶的加入提高了NBR的拉伸强度;随着芳纶用量的增大,复合材料的扯断伸长率降低;芳纶的加入降低了NBR的摩擦系数和磨损率;当芳纶用量为20份时,复合材料的综合性能最佳。加入芳纶对NBR摩擦磨损形式的改变是NBR摩擦性能提高的重要原因。     

纳米MH/AF/NBR复合材料物理力学性能及耐热阻燃机理

为了获得具有较好物理力学性能和耐热阻燃性能的橡胶密封材料,以NBR、芳纶纤维(AF)和纳米Mg(OH)₂(MH)为主要原料制备了纳米MH/AF/NBR复合材料.研究了纳米MH和AF不同配比时,复合材料的物理力学性能变化、耐热阻燃性能变化.结果表明:纳米MH对复合材料内部结构有很好的补强作用,而AF添加量较多时,与橡胶的结合强度有变差的趋势.不同配比的纳米MH与AF能够有效改善NBR的物理力学性能.当纳米MH与AF填料配比份数配比为20/10时,复合材料的拉伸强度、定伸应力可以提高4%左右,永久压缩变形降低1%左右,当纳米MH/AF份数配比为30/10时,硬度提高到73度.比较发现纳米MH的阻燃性能要优于AF,纳米MH/AF份数配比为10/10时,复合材料分解温度提高了近20℃,MH/AF填料的加入改善了NBR原有的热稳定性,且复合材料燃烧时烟气生成量较小,为该类复合材料在密封等领域进一步应用奠定了基础.     

ZDMA/NBR纳米复合材料的性能研究

研究了甲基丙烯酸锌（ZDMA）/NBR纳米复合材料的静态和动态力学性能，并与炭黑N220/NBR体系进行了对比。试验结果表明，ZDMA/NBR胶料的硫化时间应比正硫化时间适当延长。与炭黑N220/NBR体系相比，ZD-MA/NBR硫化胶的邵尔A型硬度、拉伸强度、扯断伸长率、100%定伸应力和撕裂强度均较高，且具有更好的耐热空气老化性能和耐热油性能，ZDMA/NBR胶料的贮存模量较高，动态压缩生热较小，但动态压缩永久变形较大。     

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。     

复配改性黏土/丁腈橡胶纳米复合材料的结构及性能

用不同阴离子表面活性剂十二烷基磺酸钠(SDS)和十二烷基苯磺酸钠(SDBS)与阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)复配改性无机黏土,制备了有机改性黏土/丁腈橡胶(NBR)纳米复合材料,并表征了有机黏土与纳米复合材料,考察了不同表面活性剂及配比对纳米复合材料物理机械性能的影响。结果表明,CTAB/SDS复配改性黏土/NBR纳米复合材料的层间距比CTAB改性黏土/NBR纳米复合材料增加了1.15 nm,具有更多的插层结构,橡胶基体中黏土颗粒分布细致、均匀,且黏土片层间无聚集体存在;CTAB/SDS复配改性黏土/NBR纳米复合材料的物理机械性能优于CTAB/SDBS复配改性黏土/NBR纳米复合材料及CTAB改性黏土/NBR纳米复合材料,且当CTAB/SDS(质量比)为4∶2时,纳米复合材料的拉伸强度、撕裂强度及扯断伸长率出现最大值,其中,拉伸强度和撕裂强度较CTAB改性黏土/NBR纳米复合材料分别提高了62.7%和12.3%。     

Identification of fiber misalignment in continuous fiber composites

Misaligned fibers are invariably present in nominally unidirectional high‐performance composites. Such misaligned fibers are known to affect key mechanical properties of the composite, such as the longitudinal compressive strength, longitudinal tensile modulus, fatigue endurance, shear strength, and delamination resistance (1). In this paper we present a method for the automated detection of large angle fiber misalignment (θ > 40°) in continuous fiber‐reinforced composite materials. The method relies on the application of a series of geometrical criteria based upon measurements routinely obtained during optical scanning of polished sample cross‐sections. As such, the technique is ideal for the automated identification of highly misaligned fibers in large‐area (∼ cm²) specimens that may contain several millions of individual fiber images. The criteria applied take into account the fact that prepared cross‐sections of such materials contain many damaged fibers as a result of attrition during polishing. Data obtained from three pultruded unidirectional rods reinforced with continuous carbon filaments are used to illustrate the effectiveness of this method in identifying regions where large angle misalignment occurs.     

Direct fiber formation and fiber properties of aromatic polyoxadiazoles

A novel and simple fiber formation process has been developed to fabricate aromatic polyoxadiazoles. The aromatic copolyoxadiazole solution prepared from terephthalic acid, isophthalic acid, and hydrazine sulfate in fuming sulfuric acid was utilized directly as spinning solution and was successfully wet-spun to form fiber into a coagulating bath containing sulfuric acid. In the wet-spinning process, selection of the coagulating bath was the most important factor, and the best results were obtained by the use of approximately 50 wt-% aqueous sulfuric acid. It was easy to prepare a polyoxadiazole fiber having a tenacity of more than 4 g/den. and an elongation of more than 10%. In addition, the fiber properties reached to a tenacity of 6 g/den. and an elongation of 12% under optimum spinning conditions. The wet-spun polyoxadiazole fiber showed an almost round cross section and a clear skin-core structure by microscopic observation. The fiber had a high level of thermal and dimensional stability and a high proportion of property retention at elevated temperatures, as well as all-round general fiber properties.     

锦纶纤维特性及纤维骨架材料的发展

一、锦纶骨架材料世界应用概况 锦纶66的合成及纺丝技术于1935～1937年由美国杜邦公司的Carothers发明，并于1938年实现了中试规模，第二次世界大战期间美国开始使用锦纶66帘布制造军用飞机轮胎，1947年后用于载重胎，到50年代后期，美国的载重胎用骨架材料几乎完全由锦纶66取代了人造丝。德国于1941年实现锦纶66工业化生产。日本1958年发明用锦纶6做轮胎骨架材料制造轮胎。     

Interpretation of fiber fragmentation in carbon/epoxy single fiber composites: Possible fiber pre-tension effects

The fiber straightening pre-tension applied during the sample preparation of single fiber composites is suggested here to significantly affect the number of fragments as well as the value of the Kelly-Tyson interface shear strength obtained from single filament composite tests. This implies that fragmentation tests performed under seemingly identical conditions, but in which the fiber pre-tension is not accurately controlled during sample preparation, might yield widely differing experimental results. We present and discuss a new set of experimental results dealing with fiber pre-tension effects in carbon/epoxy single fiber composites.     

The viscosity of fiber suspensions at low fiber volume fractions

The viscosities of suspensions of glass fibers in an aqueous solution of sucrose have been studied by use of a capillary viscometer. In the aligned condition in the capillary, the viscosity depends little on shear rate within the range studied or on fiber length, but increases with increasing volume fraction of the fibers. The entrance effect was found to depend strongly on fiber volume fraction and fiber length: this indicates that the suspensions are relatively resistant to flow during the initial stages while alignment takes place.     

Effect of polypropylene fiber processing conditions on fiber mechanical behavior

An investigation into the mechanical behavior of melt‐spun isotactic polypropylene (iPP) fibers is reported. Two different iPP formulations, PH835 and Exxon3854, synthesized using Ziegler–Natta and metallocene catalysts, respectively, and spun at take‐up velocities ranging from 1000 to 3000 m min^?1 were subjected to uniaxial tensile loading, cyclic loading and creep tests. The strain rate sensitivity was determined by performing strain rate jumps. Injection molded specimens from the same iPP formulations were tested under the same conditions. The fiber birefringence increases slightly with increasing take‐up velocity, while the crystallinity is approximately insensitive to this process parameter in this range of velocities. Fibers from the two iPP samples behave differently at large plastic strains despite having the same birefringence and crystallinity. Differences are also seen in creep. The behavior of fibers is significantly different from that of the injection molded samples of the same iPP and same crystallinity. These have lower strain hardening rate, smaller failure strains, close to zero strain rate sensitivity and exhibit a yield point phenomenon. The difference is associated with the different nature and spatial organization of the crystals and inter‐crystalline amorphous and mesomorphic phases. © 2014 Society of Chemical Industry     

P84纤维和普抗纤维性能介绍及应用

1前言 随着国家对大气治理力度的加大,对排放浓度要求越来越严,其它一些除尘器已不能满足新标准的要求,唯有袋式除尘器能实现这一点.滤袋作为袋式除尘器的关键部件,其性能直接影响着排放浓度和使用寿命,滤袋器的发展,远远跟不上滤袋本身的发展,新的滤材不断出现,下面仅对两种性能较突出的P4纤维和普抗纤维的性能及应用进行初步探讨.     

工程用聚丙烯腈纤维为基体的羧酸纤维的制备

采用断裂强度为12.26 cN/dtex、玻璃化转变温度高于250℃的工程用聚丙烯腈纤维(PAN-EF)为基体纤维,通过二甲基亚砜(DMSO)和氢氧化钠(NaOH)混合水解制备羧基含量(M_COOH)高且力学性能好的PAN-EF基羧酸纤维(PAN-EF-COOH),探讨了DMSO浓度、反应温度和反应时间对纤维水解效果的影响。结果表明:加入溶胀剂DMSO,可以降低PAN-EF在碱性条件下的水解难度;随着DMSO浓度增加、反应温度提高、反应时间延长,PAN-EF-COOH的M_COOH显著增大,但断裂强度逐渐降低;PAN-EF在NaOH质量分数0.1%、DMSO体积分数50%、反应温度120℃、反应时间2.5 h条件下水解,可以获得M_COOH较高且力学性能好的羧酸型纤维PAN-EF-COOH,纤维M_COOH为2.00 mmol/g、断裂强度为9.92 cN/dtex。     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Impact behavior of carbon fiber/polyethylene fiber hybrid composite: The effect of surface treatment of polyethylene fiber

Hybrid composites were prepared by adding one or two plies of polyethylene (PE) fabric to the bottom side of four-ply carbon fiber/vinylester composites. The effect of the surface treatment of PE fiber on the impact properties of carbon fiber/PE fiber hybrid composites was investigated using oxygen plasma, γ-MPS, and γ-MPS-modified polybutadiene (PB/γ-MPS) as surface modifiers. Carbon fiber/vinylester composite exhibited brittle failure with cross-shaped crack at the back side. The addition of PE fabric on the bottom side resulted in a change of the impact behavior of hybrid composites. After hybridization, the absorption of much impact energy was attributed to a considerable degree of plastic deformation in PE plies and the delamination at the interface between carbon and PE layer. However, the surface treatment of PE fiber reduced the impact energy of composites with restriction of deformation at the interface between the carbon and the PE layer. Moreover, the addition of a treated PE layer decreased the degree of deformation with a dagger-shaped deformation zone at the back side. The extent of the deformation area had a significant effect on the impact energy of the hybrid composites.