共查询到20条相似文献，搜索用时 0 毫秒
1.
As linear polyethylenes, ultrahigh‐molecular‐weight polyethylene (UHMWPE) and high‐density polyethylene (HDPE) have the same molecular structure, but the large difference in viscosity between them makes it difficult to obtain well‐mixed blends. An innovative eccentric rotor extruder (ERE) generating an elongational flow was used to prepare HDPE/UHMWPE blends within short processing times. Compared with the obvious two‐phase morphology of a sample from a twin‐screw extruder observed with a scanning electron microscope, few small UHMWPE particles were observed in the HDPE matrix for a sample from the ERE, indicating the good mixing on a molecular level of HDPE/UHMWPE blends achieved by the ERE during short processing times. The morphological changes of blends prepared using the ERE evidenced the good integration of HDPE and UHMWPE even though the UHMWPE content is up to 50 wt% in the blends. Moreover, all blends retained most of the intrinsic molecular weight. The good mixing was further confirmed from the thermal, crystallization and rheological behaviors determined using differential scanning calorimetry and dynamic rheological measurements. Importantly, the 50/50 blend presented improved mechanical properties, especially super‐impact strength of 151.9 kJ m?2 with incomplete‐break fracture state. The strengthening and great toughening effects of UHMWPE on the blends were attributed to the addition of unwrapped UHMWPE long molecular chains. The effective disentanglement mechanism of UHMWPE chains under elongational flow was explained schematically by a non‐parallel three‐plate model. © 2019 Society of Chemical Industry 相似文献
2.
以天然橡胶为基体,微米Al2O3和纳米Al2O3为导热填料,比较了纳米Al2O3和微米Al2O3填充的导热橡胶的导热性能和物理机械性能,并将2种粒子以不同配比加入天然橡胶基体中,对其影响进行了探讨.结果表明,随着微米Al2O3填充份数的增加,天然橡胶的热导率增大,物理机械性能先升高后下降;在相同填充量下,微米Al2O3填充的导热橡胶比纳米Al2O3填充的导热橡胶具有更好的导热性能和物理机械性能;在合适的配比下,纳米Al2O3与微米Al2O3混合填充的导热橡胶的导热效果优于单一使用Al2O3粒子的填充效果. 相似文献
3.
Xiang Yang Zhang Wen Chen Kun Li Yong-kang Peng Zhi-hang Sun Chen-cheng Wu Wen-jun Cao Jian-hui 《International Journal of Applied Ceramic Technology》2022,19(6):3267-3278
Continuous alumina fiber–reinforced alumina matrix composites (Al2O3f/Al2O3 composites) were produced via sol–gel process, then the high-temperature mechanical property and thermal shock resistance of Al2O3f/Al2O3 composites were investigated. The results showed that the composites exhibited excellent high-temperature properties. The mechanical property of the composites was affected by heat treatment (prepared at 1100°C exhibited the most desirable mechanical property). The tensile strength of the composites abruptly decreased at higher temperatures. Although the mechanical property of the composites deteriorated after the thermal shock test was conducted at high temperatures, they exhibited excellent thermal shock resistance. After 50 thermal shock tests conducted at 1300 and 1500°C, the flexural strength of the composites was found to be 124.34 and 93.04 MPa, thus showing a decrease in strength with the increasing temperature. 相似文献
4.
Jen‐Taut Yeh Chuen‐Kai Wang Ping Hu Yu‐Ching Lai Lu‐Kai Huang Fang‐Chang Tsai 《Polymer International》2012,61(6):982-989
An investigation of the influence of the contents of original and modified attapulgite (ATP) on the ultradrawing properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE)/ATP (FAx) and UHMWPE/modified ATP (FAmx) as‐prepared fibers is reported. Similar to what is found for the orientation factor values, the achievable draw ratios (Dra) of the FAx and FAmx as‐prepared fibers approach a maximum value as the original ATP and/or modified ATP contents reach their corresponding optimum values. The maximum Dra value obtained for FAmx as‐prepared fiber specimens is significantly higher than that for FAx as‐prepared fiber specimens prepared at the optimum original ATP content. Similar to what is found for the orientation factors and achievable drawing properties, the tensile strength (σf) and initial modulus (E) of both drawn F2Ax and F2Amx fiber series specimens with a fixed draw ratio reach maximum values as the original and/or modified ATP contents approach the optimum values, respectively. The σf and E values of the F2Amx fiber specimens are always significantly higher than those of the corresponding F2Ax fiber specimens prepared at the same draw ratios and ATP contents but without being modified. To understand the interesting ultradrawing, orientation and tensile properties of FAx and FAmx fiber specimens, Fourier transform infrared spectral, specific surface area, transmission electron microscopic and elemental analyses of the original and modified ATPs were performed. Copyright © 2012 Society of Chemical Industry 相似文献
5.
综述了纳米级陶瓷、粘土、碳纳米管、金属及金属氧化物、液晶等填料对超高分子量聚乙烯的改性应用,同时还探讨了其改性机理,并对其应用前景做了展望。 相似文献
6.
选用硅烷偶联剂KH-550,KH-560和钛酸酯偶联剂NDZ-201作为表面改性剂,对超高相对分子质量聚乙烯(UHMWPE)冻胶纤维在萃取阶段进行表面处理,经干燥、超拉伸制得表面改性UHMWPE纤维。采用红外光谱仪、接触角测量仪测定了纤维的表面化学结构和表面润湿性能,采用单纤维树脂包埋-拔出法测定了纤维与树脂基体的界面剪切强度,比较了改性前后纤维的力学性能变化。结果表明:改性后纤维表面引入了极性基团,硅烷偶联剂KH-550对UHMWPE纤维的表面改性效果最好。采用质量分数为1%的硅烷偶联剂KH-550溶液处理后,纤维与环氧树脂间的界面剪切强度提高了87.8%,纤维的断裂强度和模量分别提高了6.9%和32.6%。 相似文献
7.
Xiaoling Liu Jimei Xue Fan Yang Fang Ye Xiaomeng Fan Laifei Cheng 《Journal of the American Ceramic Society》2020,103(11):6255-6264
A new kind of structural and functional integration ceramic matrix composite material was prepared from high-performance alumina (Al2O3) fibers and absorbing silicon carbonitride (SiCN) ceramics via a combination of polymer infiltration pyrolysis (PIP) and chemical vapor infiltration (CVI) methods. The Al2O3 fiber annealed at its cracked temperature had enhanced permittivity, because the sizing agent on the Al2O3 fiber surface was cracked into pyrolysis carbon. For PIP + CVI Al2O3f/SiCN composites, PIP SiCN matrix with low conductivity was used as the matching phase, while CVI SiCN matrix with medium permittivity and dielectric loss was regarded as the reinforcing phase distributed in porous PIP SiCN matrix and inter-bundles of Al2O3 fiber to improve their mechanical and microwave absorption properties. The fracture toughness and flexural strength of Al2O3f/SiCN composite were determined to be 9.4 ± 0.5 MPa m1/2 and 279 ± 28 MPa, respectively. Based on the design principles for impedance matching, the Al2O3f/SiCN composites before and after oxidation were used as loss and impedance layers, respectively. It was found that the optimized composite had the lowest reflection coefficient (RC) of −70 dB and the effective absorption bandwidth covering the whole X-band. In conclusion, Al2O3f/SiCN composite can serve as a high-temperature structural material with excellent microwave absorption properties for aerospace applications. 相似文献
8.
Jen‐Taut Yeh Yu‐Ching Lai Hai Liu Yao‐Chi Shu Chi‐Yuan Huang Kuo‐Shien Huang Kan‐Nan Chen 《Polymer International》2011,60(1):59-68
The influence of formation temperature on the ultradrawing properties of ultrahigh‐molecular‐weight polyethylene/carbon nanotube (UHMWPE/CNT) fiber specimens is investigated. Gel solutions of UHMWPE/CNT with various CNT contents were gel‐spun at the optimum concentration and temperature but were cooled at varying formation temperatures in order to improve the ultradrawing and tensile properties of the UHMWPE/CNT composite fibers. The achievable draw ratio (Dra) values of UHMWPE/CNT as‐prepared fibers reach a maximum when they are prepared with the optimum CNT content and formation temperature. The Dra value of UHMWPE/CNT as‐prepared fibers produced using the optimum CNT content and formation temperature is about 33% higher than that of UHMWPE as‐prepared fibers produced using the optimum concentration and formation temperature. The percentage crystallinity (Wc) and melting temperature (Tm) of UHMWPE/CNT as‐prepared fiber specimens increase significantly as the formation temperature increases. In contrast, Wc increases but Tm decreases significantly as the CNT content increases. Dynamic mechanical analysis of UHMWPE and UHMWPE/CNT fiber specimens exhibits particularly high α‐transition and low β‐transition, wherein the peak temperatures of α‐transition and β‐transition increase dramatically as the formation temperature increases and/or CNT content decreases. In order to understand these interesting drawing, thermal and dynamic mechanical properties of the UHMWPE and UHMWPE/CNT as‐prepared fiber specimens, birefringence, morphological and tensile studies of as‐prepared and drawn fibers were carried out. Possible mechanisms accounting for these interesting properties are proposed. Copyright © 2010 Society of Chemical Industry 相似文献
9.
Al2O3陶瓷的动态力学性能研究 总被引：15，自引：0，他引：15
本文采用ＳＨＰＢ装置对９５瓷、９７瓷和９９瓷的动态力学性能进行实验研究。结果表明Ａｌ２Ｏ３陶瓷在高冲击载荷下其抗压强度增高,其增加幅度随Ａｌ２Ｏ３含量增加而加大,并分析了机理。 相似文献
10.
Shi Fu Zengchao Yang Honghua Li Liang Wang Yong Li Jiangtao Li 《International Journal of Applied Ceramic Technology》2023,20(3):1855-1864
Si3N4 ceramics were prepared by gas pressure sintering at 1900°C for 12 h under a nitrogen pressure of 1 MPa using Gd2O3 and MgSiN2 as sintering additives. The effects of the Gd2O3/MgSiN2 ratio on the densification, microstructure, mechanical properties, and thermal conductivity of Si3N4 ceramics were systematically investigated. It was found that a low Gd2O3/MgSiN2 ratio facilitated the thermal diffusivity of Si3N4 ceramics while a high Gd2O3/MgSiN2 ratio benefited the densification and mechanical properties. When the Gd2O3/MgSiN2 ratio was 1:1, Si3N4 ceramics obtained an obvious exaggerated bimodal microstructure and the optimal properties. The thermal conductivity, flexural strength, and fracture toughness were 124 W·m−1·k−1, 648 MPa, and 9.12 MPa·m1/2, respectively. Comparing with the results in the literature, it was shown that Gd2O3-MgSiN2 was an effective additives system for obtaining Si3N4 ceramics with high thermal conductivity and superior mechanical properties. 相似文献
11.
Jen‐Taut Yeh Chuen‐Kai Wang Alice Yeh Lu‐Kai Huang Wen‐Hung Wang Kuo‐Huang Hsieh Chi‐Yuan Huang Kan‐Nan Chen 《Polymer International》2013,62(4):591-600
Ultrahigh molecular weight polyethylene (UHMWPE)/nanosilica (F2Sy) and UHMWPE/modified nanosilica (F2Smx‐y) as‐prepared fibers were prepared by spinning of F2Sy and F2Smx‐y gel solutions, respectively. Modified nanosilica particles were prepared by grafting maleic anhydride grafted polyethylenes onto nanosilica particles. The achievable draw ratios (Dra) of F2Sy and F2Smx‐y as‐prepared fibers approached a maximal value as the original and modified nanosilica contents reached corresponding optimum values; the maximal Dra value obtained for F2Smx‐y as‐prepared fiber specimens was significantly higher than that of the F2Sy as‐prepared fiber specimens prepared at the optimum nanosilica content. The melting temperature and evaluated lamellar thickness values of F2Sy and F2Smx‐y as‐prepared fiber series specimens decrease, but crystallinity values increase significantly, as their original and modified nanosilica contents respectively increase. Similar to the achievable drawing properties of the as‐prepared fibers, the orientation factor, tensile strength (σf) and initial modulus (E) values of both drawn F2Sy and F2Smx‐y fiber series specimens with a fixed draw ratio reach a maximal value as the original and/or modified nanosilica contents approach the optimum values; the σf and E values of the drawn F2Smx‐y fiber specimens are significantly higher than those of the corresponding drawn F2Sy fiber specimens prepared at the same draw ratios and nanosilica contents but without being modified. To understand the interesting ultradrawing, thermal, orientation and tensile properties of F2Sy and F2Smx‐y fiber specimens, Fourier transform infrared, specific surface area and transmission electron microscopy analyses of the original and modified nanosilica were performed in this study. © 2012 Society of Chemical Industry 相似文献
12.
综述了超高分子量聚乙烯(UHMWPE)、碳纳米管(CNTs)、UHMWPE/CNTs复合体系及其纤维的研究现状,以及CNTs的添加对UHMWPE/CNTs复合体系及其纤维性能的影响;添加CNTs可有效提高UHM-WPE的耐磨性、电学性能、力学性能以及UHMWPE纤维的抗蠕变性能和热稳定性能;指出CNTs对UHM-WPE改性过程中存在的主要问题是CNTs分散性差,CNTs的生产成本高,UHMWPE/CNTs的改性机理有待进一步深入,并进一步拓宽UHMWPE/CNTs复合体系及其纤维的应用领域。 相似文献
13.
研究选择了HDPE 5种不同粘均分子量样品,分子量范围从8.00×10~4到3.29×10~6.通过应力-应变曲线,缺口试件在拉伸状态下的缺口形状宏观变化观察及SEM观察,以及结晶度测量,研究了PE的拉伸行为,试验表明,NMW-PE(Normol MW-PE)和UHMW-PE不仅在宏观力学性能上存在巨大差异,而且在微观结构和形态上也存在显著的差别。结晶和缠结情况是决定宏观性能差异主要因素,屈服强度的变化主要由结晶度变化决定的,断裂强度的变化主要由缠结因素决定的。形貌上差异也和结晶缠结两个因素紧密相关。 相似文献
14.
15.
超高分子量聚乙烯的成型工艺及改性研究进展 总被引：2，自引：0，他引：2
本文介绍了超高分子量聚乙烯材料的基本性能,并由其性能决定的成型工艺,由于超高分子量聚乙烯熔体粘度极高,加工比较困难,限制了其的应用;通过综述近年来的超高分子量聚乙烯的改性研究进展,认为只有进行有力的改性研究,才可以将超高分子量聚乙烯的优异性能得到更为广泛研究和应用。 相似文献
16.
Partha Haldar Tapas Kumar Bhattacharya Nipu Modak 《International Journal of Applied Ceramic Technology》2021,18(1):110-118
Sintering of alumina from 1500°C to 1650°C and tribo-mechanical properties at room temperature had been investigated using nano CuO as a sintering aid. Bulk density gradually increases with sintering temperature from 1500°C to 1600°C and is optimized at 1600°C, beyond this, bulk density does not significantly increase at 1650°C. The addition of 2 wt% CuO showed the best result on densification. Densification of about 97.74% was attained at 1600°C with the incorporation of 2 wt% CuO. Nano CuO at grain boundaries forms CuAl2O4 liquid which modifies the morphology of the grain and improves mechanical properties. The formation of self-lubricating tribo-film on the wear track results in a low coefficient of friction <0.2 and reduces specific wear rate. 4 wt% CuO addition increases contact tensile stress (σmax) by 51.2% and high Hertzian contact pressure (Pmax≈1.51 GPa) causes plastic deformation of wear track. The re-solidified strengthening bond phase on the wear track simultaneously increases in friction coefficient and wear resistance with CuO addition. The optimizing effect of CuO addition shows that 2 wt% significantly decreases wear rate, and increases hardness and fracture toughness. 相似文献
17.
The polymerization of thiophene (TP), in bulk and in solution in CHCl3 by FeCl3 resulted in the formation of a polymer which was characterized by FTIR as polythiophene (PTP). High yield was realized in the latter case. The polymerization of TP with FeCl3 and nanodimensional Al2O3 resulted in the formation of a nanocomposite which was partly dispersible in aqueous and non‐aqueous media. The dispersibility appeared to be higher when the polymerization was conducted in a suspension containing a higher amount of Al2O3. Scanning electron micrographs showed globular particles and the presence of clusters of composite particles. Transmission electron micrographic (TEM) analyses revealed the particle size of the composite to be in the range 22–74 nm. Thermal analyses (TG/DTA) revealed the outstanding stability of PTP–Al2O3 composites compared to that of PTP. The conductivity of PTP and of PTP–Al2O3 composite was of the order of 10?3 S cm?1 for samples doped with I2. © 2003 Society of Chemical Industry 相似文献
18.
Lei He Hongtao Yu Mengshi Zeng Ting Luo Jingsong Liu 《Journal of the American Ceramic Society》2018,101(11):5110-5119
0.73ZrTi2O6–0.27MgNb2O6 ceramics with various Al2O3 contents (0‐2.0 wt%) were prepared by conventional ceramic route. The effects of Al2O3 on the phase composition, microstructure, conductivity, and microwave dielectric properties were systematically investigated. The coexistence of a disordered α–PbO2‐type phase and a rutile second phase was found in all compact ceramics with low Al2O3 contents (x = 0, 0.5, and 1.0 wt%), while a corundum phase was detected when Al2O3 additive increased to 1.5 and 2.0 wt% based on X‐ray diffraction results. With the addition of Al2O3, the decreased grain size of the matrix phase was observed using field‐emission scanning electron microscope, accompanied with increased resistivity and band‐gap energy. Additionally, Al2O3 additives efficiently improved the quality factor of the ceramics. After sintering at 1360°C for 3 hours, the ceramic with 1.0 wt% Al2O3 exhibited excellent microwave dielectric properties: a dielectric constant of 43.8, a quality factor of 33 900 GHz (at 6.6 GHz), and a near‐zero temperature coefficient of resonant frequency (3.1 ppm/°C). 相似文献
19.
Yi An Hao Liu Zhoufu Wang Yan Ma Xitang Wang 《International Journal of Applied Ceramic Technology》2024,21(2):1104-1118
The corrosion resistance and mechanical properties directly affects the operation and service life of Al2O3-Cr2O3 refractories used in waste incinerators. In this study, ZrO2 particles were introduced via vacuum impregnation to adjust microstructure and properties of Al2O3-Cr2O3 refractories. The results showed that the impregnated ZrO2 particles and increasing impregnation times resulted in the decreased median pore size and increased compactness, and mechanical strengths of refractories were elevated from the inhibited cracks propagation by ZrO2 particles. The decreased amounts of large pores and increased amounts of small pores from the filled ZrO2 particles inhibited penetration of low melting point phases, and the formed CaZrO3 phase from the reactions between corrosion reagent and ZrO2 particles increased the viscosity of penetrated corrosion reagent, resulting in the decreased penetration index from 8.57% to 2.58%. Meanwhile, the filled ZrO2 particles around alumina particles prevented reactions between molten corrosion reagent and alumina, leading to the decreased corrosion index from 3.78% to .74%. The decreased pore size and formation of CaZrO3 phase were primary factors that enhanced the penetration resistance. And formation of wrapped layers from ZrO2 particles around alumina particles presented prominent effects on the strengthened corrosion resistance of Al2O3-Cr2O3 refractories. 相似文献
20.
Shishuai Li Yongfeng Xia Dongxu Yao Hanqin Liang Yu-Ping Zeng 《International Journal of Applied Ceramic Technology》2023,20(1):465-474
Sintered reaction-bonded silicon nitride (SRBSN) with high thermal conductivity was obtained using (Y0.96Eu0.04)2O3 and MgO as sintering additives. Green compacts were nitrided at 1400°C for 4 h. Post-sintering was carried out at 1850 and 1900°C for 4 h, respectively. In reaction-bonded silicon nitride (RBSN) doped with Y2O3 and MgO, the β-Si3N4 content and nitridation degree were 51.1% and 93.8%, respectively. However, the β-Si3N4 content and nitridation degree were 72.6% and 96.7% in a nitrided compact doped with (Y0.96Eu0.04)2O3 and MgO. After post-sintering, the phase composition, microstructure, mechanical properties, and thermal conductivity were investigated. After sintering at 1900°C for 4 h, the thermal conductivity of SRBSN doped with (Y0.96Eu0.04)2O3 and MgO was increased by 16.5% compared to that of the samples doped with Y2O3 and MgO. The highest hardness of 1639 HV and the good flexural strength of 776.4 MPa were also achieved in the sample doped with 2-mol.% (Y0.96Eu0.04)2O3 and 5-mol.% MgO. 相似文献