补强前后粘胶基炭纤维中的分形

缺陷是影响粘胶基炭纤维强度的重要因素，补强前后粘胶基炭纤维强度的提高与纤维中的缺陷的减少有着密切的关系。粘胶基炭纤维中存在着自相似性，具有明确的分形结构，本文用小角X-ray散射法（SAXS）测定了粘胶基炭纤维补强前后的分形维数，定量的描述了粘胶基炭纤维中缺陷的变化，并总结了粘胶基炭纤维的分维与结构和性能之间的关系。     

热解条件对粘胶基炭纤维（RCF）抗拉强度的影响

采用化学气相沉积法,利用四氯化碳在开放系统中对粘胶基炭纤维（RCF）进行了连续化补强处理,研究了热解条件对补强效果的影响,用扫描隧道电镜（STM）、扫描电子显微镜（SEM）对补强前后的炭纤维进行了微观观察,并利用热解沉积机理对结果进行了解释。     

炭纤维(CF)补强处理

对炭纤维的补强技术做了总结,讨论了炭纤维补强的可能性及强度影响因素,并且介绍了一些补强方法所取得的成果。     

代替钢筋的炭纤维补强材料

日本九州大学研究生部的太田俊昭教授 ,进行了用非硬化型炭纤维补强材料作成的混凝土床板的加载试验。此次加载试验以质轻、低成本的炭纤维补强材料代替了钢筋 ,其结果在设计荷载 2倍的环境下也没发现挠曲、变形等现象 ,这充分证实了炭纤维补强材料的耐久性。太田教授认为 ,钢筋混凝土时代已被低能源·ＩＴ时代代替 ,炭纤维便是最适合本时代的材代替钢筋的炭纤维补强材料     

不同种类碳纤维增强酚醛树脂烧蚀复合材料的性能对比

对比了聚丙烯腈(PAN)基碳纤维(PCF)和粘胶基碳纤维(RCF)的密度、平均比热容、拉伸性能,分析了PCF和RCF的表面形貌,研究了PCF增强S-157酚醛树脂(S-157 PF)复合材料(S-157 PF/PCF)和RCF增强S-157PF复合材料(S-157 PF/RCF)的烧蚀性能和弯曲性能,并对复合材料弯曲断口的微观形貌进行分析。结果表明,与PCF相比,RCF的密度略小,平均比热容略大,纤维表面粗糙,拉伸性能远低于前者;S-157 PF/RCF的烧蚀性能优于S-157 PF/PCF,但弯曲性能较差。     

n-C7H16/CCl4热解处理对粘胶基碳纤维性能的影响

采用浸渍热解法,以n-C_7H_(16)/CCl_4为热解质,讨论浸渍液体积比、热解温度等对粘胶基碳纤维(RCF)拉伸性能的影响。结果表明,经热处理后纤维线密度降低,表面缺陷减少,当n-C_7H_(16)/CCl_4为2:3(体积比),热解温度900～1100℃时,碳纤维拉伸强度可提高17％。用韦氏统计理论对强度分布进行分析.证实经热解处理后,RCF强度分布更集中,均匀性更好。     

新材料

可现场加工的CFRP制混凝土补强材料日本鹿岛和住友化学工业公司共同开发出炭纤维增强塑料(CFRP)制混凝土补强材料。称之为“现场加工型CFRP筋”的这种混凝土补强材料的制造方法,是将经浸渍的热固性树脂的柔软绳索状炭纤维,运到现场,固化成任意的形状。然后给炭纤维通电,利用通电时所产生的热量使热固性树脂固化,即为CFRP制的混凝土补强材料。如直径为10mm 时,在炭纤维上的电压为10V/m,由于炭纤维的电阻产生热量,使升温到150℃状态并保持30分钟,可以成型任何形状的CFRP加强筋。     

从沥青基炭纤维看炭纤维的现状和未来

目前,世界上以日、美等国为中心,炭纤维的年产量已达6000吨以上,并继续以超过10％的年增长率递增,它对提高飞机及体育和娱乐用品的性能及轻便化起了较大的推动作用。炭纤维因其原料的不同有聚丙烯腈基炭纤维、沥青基炭纤维、粘胶基炭纤维和气相生长炭纤维等。现在,形成较大市场的是聚丙烯腈基炭纤     

由化学改性粘胶丝快速制备连续炭纤维新工艺的研究

采用了一种新的高效化学改性法和相应的烧结工艺，可在较低温度下快速制得性能优良的连续化粘胶基炭纤维。对化学改性剂中混合多元胺、表面活性剂的作用作了探讨．对气氛、升温速率等工艺参数的影响作了研究。通过正交优化设计制定出合理的连续绕结工艺。此法可使纤维经约6小时处理后．1000℃时形成强度为1.8GPa，模量为75GPa的炭纤维。     

气液双效法对炭纤维力学性能的影响

讨论了气液双效法表面处理对炭纤维力学性能,特别是对抗拉强度和断裂伸长的影响。证明气液双效法表面处理能明显提高炭纤维的抗拉强度和断裂伸长、其效果与浸润涂层后炭纤维的增重量和气相氧化程度有关。对抗拉强度较低的炭纤维其补强效果更好。     

THE TENSILE STRENGTH OF PORCELAIN1

A method of accurately determining the tensile strength of porcelain has been developed. The ratio of tensile to compression strength was found to be 5.9 for the special porcelain studied. Triaxial porcelains gave an average ratio of 7.66. The tensile strength tests show in general a little more variation than compression strength tests. The tensile strength is of more significance in judging the quality of porcelain than it has been commonly considered.     

碳纤维拉伸强度的离散性分析

纤维的力学性能受到纤维缺陷、晶粒大小等多种因素的影响.本文以Weibull理论为基础,对碳纤维的拉伸强度进行了概率统计分析,探讨了纤维拉伸强度与纤维单丝长度、纤维单丝直径之间的关系.     

空气氧化刻蚀提高PAN基炭纤维抗拉强度的研究

用空气氧化刻蚀（附浸渍预处理）的方法对通用级（类似T－300）PAN基炭纤维进行处理。以NaOH,HNO3,H2SO4,(H2SO4 KMnO4)为浸渍液，研究了直接空气氧化刻蚀中的氧化温度，氧化时间，浸渍液浓度等因素对炭纤维抗拉强度的影响。结果表明：在优化工艺条件下，炭纤维的抗拉强度可由3．73GPa提高到4．52GPa。     

热塑性复合材料板材拉伸强度近似计算

针对热塑性复合材料拉伸强度,以亚麻增强聚丙烯机织层合复合材料板材为例,结合理论分析,首先对其进行理想条件下的强度计算,通过推导得到理想状况下的强度理论计算公式,进而结合具体试验条件,在此理论计算公式基础上引进板材经、纬向纤维伸直系数aj、aw作为修正系数进行修正。利用多项式拟合,最终得出符合试验条件下的强度近似计算公式及拟合曲线。     

The effect of atmospheric plasma treatment of recycled carbon fiber at different plasma powers on recycled carbon fiber and its polypropylene composites

To increase the mechanical properties of recycled carbon fiber-reinforced polypropylene (PP) composites, recycled carbon fibers (RCF) were subjected to atmospheric plasma treatment at different plasma powers (100, 200, and 300 W). The changes on surface topography and roughness of RCF were examined by atomic force microscopy. Plasma treatment of RCF increased the roughness value of RCF. The variation of surface elemental compositions and tensile strength of RCF were determined by using X-ray photoelectron spectroscopy and tensile test, respectively. Plasma-treated RCF-reinforced PP composites were fabricated using high speed thermo-kinetic mixer. Plasma treatment of RCF at 100 W increased the tensile and flexural strength values of RCF-reinforced PP composites considerably by 17 and 11%, respectively. However, plasma treatment of RCF at higher plasma powers (200 W and 300 W) decreased tensile and flexural strength values of composites because of the etching of RCF. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47131.     

Al2O3 薄片拉伸切口强度及其概率分布的研究

对Ａｌ２Ｏ３薄片进行了拉伸实验研究,实验采用了金属粘接过渡与铰链式拉伸夹具。结果表明Ａｌ２Ｏ３薄片的拉伸断裂强度与切口强度遵从正态分布、对数正态分布与Ｗｅｉｂｕｌｌ分布。实验还给出切口强度分布参数与拉伸断裂强度分布参数之间的关系式。利用该关系式和光滑试件测定的断裂强度及其概率分布,可对具有给定应力信中系数的陶瓷构件的断裂强度及概率分布进行预测,为构件的安全可靠性评估提供依据,并节约人力、物力与实验     

RPM管环向拉伸强度的测试

针对RPM管环向拉伸强度测试中采用板条状试样所存在的问题,理论分析和试验研究表明通过改变试样形状和尺寸可明显改善测试结果.     

EFFECT OF IRON OXIDE ON TENSILE STRENGTH OF PORCELAINENAMEL*

This investigation was conducted for the purpose of determining whether iron oxide affected the tensile strength of enamel. The results indicate that ferric oxide appreciably reduces the enamel strength and ferrous oxide may have an even greater effect. The possible relation of chipping of the enamel to the iron oxide content is noted.     

早龄期高强混凝土拉伸徐变特性

通过早龄期混凝土拉伸基本徐变的实验,研究了不同水灰比,加载龄期、加载初始应力强度比(应力水平)等参数条件下的早龄期高强混凝土拉伸徐变特性.结果表明:龄期0.5,0.75d和1d加载的混凝土表现出较大的徐变变形,并且徐变速度在持续加载一段时间后随龄期的推迟而急速下降:龄期0.5,0.75d加载的混凝土徐变表现出较大的非线性,同一加载龄期下,加载初始应力强度比越大,比徐变越大,加载初期的徐变速度越快;但加载龄期在1,3,7d的混凝土徐变仍表现出较明显的线性特征.同一加载龄期、同一加载应力强度比的条件下,水灰比越大,比徐变越大,而且加载龄期越早,比徐变的差异越明显.     

Recycling carbon fiber from composite waste and its reinforcing effect on polyvinylidene fluoride composite: Mechanical,morphology, and interface properties

Recycled carbon fiber (RCF) was reclaimed from thermoset composite waste and employed as reinforcement from 0 to 30 wt% to prepare polyvinylidene fluoride (PVDF)/RCF composite. Commercial virgin carbon fiber (VCF) was used as comparison. The surface morphology, chemistry, and tensile properties of carbon fibers were investigated by Scanning Electron Microscopy (SEM), X‐Ray Photoelectron Spectroscopy (XPS), and tensile test. Results showed that the roughness, O/C ratio and –COO content of RCF surface were significantly improved after recycling. In addition, the single fiber tensile strength and modulus of RCF was lower than that of VCF. The interfacial adhesion between RCF and PVDF was much stronger due to the high chemical activity and roughness over the RCF surface. Mechanical properties of composites were investigated by flexural test, impact test, and Dynamic Mechanical Analysis (DMA). It is found that the PVDF/RCF composite showed higher flexural properties, storage modulus, and lower impact strength, which indicated the strong interfacial adhesion, played an important role in reinforcing. The morphology of fracture further demonstrated the strong interface in PVDF/RCF composite. The fiber length distribution and crystallinity of composites were also evaluated to characterize the composites. The work develops potential for recycling and reuse of carbon fiber, and also expands the application of PVDF based composite. POLYM. COMPOS., 38:2544–2552, 2017. © 2015 Society of Plastics Engineers