Potassium titanate whiskers

S/3N4 Whiskers Color Shape Density (glcm ) Diameter (pm) Length (pm) Tensile Strength (GPa) Elasticity Modulus (GPa) Moh s Scale of Hardness Melting Point (°C) 

Potassium titanate whiskers can be used as thermal insulation material, electrical insulating material, catalyst carriers, filtration material, friction material, and so on based on their special performances. In addition, they are applied as 

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More than 100 different materials have to date been produced as whiskers and characterized. However, only SiC- (50 to 100 t, 1996) and potassium titanate whiskers (ca. 5000 t) have achieved commercial importance. Important properties of whiskers are summarized in Table 5.2-18. 

Silicon carbide whiskers are generally manufaclured by a metal-catalyzed process, in which carbon and silicon are condensed from the gas phase. Another jtroccss utilizes rice husks decomposed at 500°C. At temperatures of 1800°C the carbon/Si02-mixture formed is converted into a-SiC. Potassium titanate whiskers are synthesized from potassium molybdate, potassium carbonate and litanium dioxide at temperatures above 1200°C. 

Potassium titanate whiskers were found to improve the tribological properties of NAO friction materials. These soft, synthetic refractory materials stabilize friction level, reduce pad wear, noise, fade, thermal conductivity, control porosity, and provide thermal reinforcement. Fibrous potassium titanates are being replaced by platelet and powder versions because of health concerns associated with respirable fibers. 

Tjong, S. C. and Meng, Y. Z. 1999. Microstructural and mechanical characteristics of compatibilized polypropylene hybrid composites containing potassium titanate whisker and liquid crystalline copolyester. Polymer 40 7275-7281. 

Well dispersed potassium titanate whiskers can serve as partially heterogeneous nucleating agents in PEEK resin to promote its crystallization, which is beneficial in increasing the mechanical and tribological properties of PEEK. ... 

Four weeks after intratracheal instillation of 2 mg of respirable potassium titanate whiskers into male Wistar rats RNA extracted from LPS stimulated alveolar macrophages expression of IL-la was increased (Tsuda et al. 1996,1997). The expression of IL-la mRNA was by fibres was greatest in potassium octatitanate whisker > UICC crocidolite > UICC chrysotile > refractory ceramic fibre-instilled rat alveolar macrophages. The levels of IL-la and TNF-a mRNA in alveolar macrophages (expressed in their ratio to P-actin) peaked at 1 month and 3 days after exposure to octatitanate, respectively. 

Jiazhen Lu, Xiaohua Lu. Elastic interlayer toughening of potassium titanate whiskers-nylon66 composites and their fractal research. 

Higher tensile strength than potassium titanate whiskers... 

The self-assembly method has attracted much attention because it can form monomolecular films on the surface of many matrixes, such as silicon oxide and titanium oxide. Considering potassium titanate whiskers as an example, the similar surface structure (Ti-O) between potassium titanate whiskers and titanium oxide means there is some comparability between them. 

Wang et al. surface modified potassium titanate whiskers (PTW) using the self-assembly of octadecyl trichloro silane (OTS). The process is as follows. Add 0.5 mL of OTS to the suspension liquid of whiskers (10 g) and heptane (200 ml) with stirring and continue stirring for 20 minutes after the whiskers are evenly dispersed in the solution. Then the mixture is filtered and washed several times to remove dissociative OTS and dried in a vacuum. 

As shown in Table 3.16, the whiskers modified with OTS have lower surface energy, lower polar component, and better hydrophobic and lipophilic properties than untreated whiskers. The dispersive component ratio of potassium titanate whiskers modified with OTS to OTS molecules is much closer to the dispersion value of the -CH2- group rather than the -CH3-group, which indicates that the whisker surface modified with... 

Table 3.16 Surface Energy, Dispersive, and Polar Components of Unmodified/Modified Potassium Titanate Whiskers...

Table 3.17 shows the adsorption work and interfacial tension of potassium titanate whiskers before and after modification with OTS with water and benzene. After modification with OTS, the adsorption work of modified whiskers to oil is lower than to water, and the interfacial tension of whiskers to water increases while that to oil is close to zero. These prove that whiskers treated with OTS have more typical hydrophobicity and lipophilicity. 

Table 3.17 Adsorptive Work and Interfacial Tension of Potassium Titanate Whiskers before and after Modification with Water...

The surface morphology of whiskers can be characterized and analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Elgures 3.19 and 3.20 show SEM images and EDS spectrum of potassium titanate whiskers treated with polymethyl methacrylate (PMMA). According to the SEM results, the surface of unmodified whiskers is smooth without attachments, while the surface of modified whiskers is rough with attachments. The EDS spectrum of modified whiskers shows the characteristic peak of carbon (C). Both SEM and EDS results prove that the whisker surface is cladded with PMMA molecules.35... 

Figure 3.19 SEM images of potassium titanate whiskers before and after modification, (a) Unmodified, (b) Modified.

The surface characteristics of modified whiskers can be analyzed by detecting the thermal weight loss curve. Figure 3.21 shows the thermal gravimetric analysis (TGA) curve of potassium titanate whiskers modified with PMMA. 

Figure 3.21 TGA curve of modified potassium titanate whiskers.

Changsheng Li, Wenbin Mu, Jie Hu. Preparation and tribology capability of potassium titanate whiskers reinforced MC nylon. Engineering Plastics Application, 36(l) 4-7, 2008. 

Xiuyin Zhang, Wensheng Wu, Aifeng Tian. The effect of whisker fraction on flexural strength of whisker-PMMA composite reinforced with potassium titanate whiskers./owma/ of Clinical Stomatology, 25(3) 151-154, 2009. 

Changsong Wang, Xin Feng, Xiaohua Lu. Surface modification of potassium titanate whiskers with w-octadecyltrichlorosilane, Acta Pbysico-Chimica Sinica, 21(6) 586-590, 2005. 

Weiping Chen. The study of the surface modification and characterization and interface property of potassium titanate whiskers. Nanjing Nanjing University of Science and Technology, 2004. 

Considering epoxy resin filled with potassium titanate whisker as an example, the specific operation is as follows. Mix bisphe-nol A-glycidyl methacrylate (bis-GMA) and triethylene-glycol dimethacrylate at a mass ratio of 1 1 as a resin matrix add initiator benzoyl peroxide (BPO) and the polymerization inhibitor butylated hydroxytoluene (BHT, 264) and blend uniformly. Then mix surface-modified potassium titanate whisker into the resin, fill into the mold, and cure in an oven at 120°C for 30 minutes. 

Figure 4.9 shows the changing curve of the MFI of PP filled with different amounts of whiskers. M-PP represents PP modified with basic magnesium sulfate whiskers K-PP represents PP treated with potassium titanate whiskers. 

When potassium titanate whiskers modified by a coupling agent are filled into PE material with ultrahigh molecular weight, the hardness of composite material increases significantly, as shown in Table 4.5. 

In recent years, there has been a breakthrough in the manufacturing cost of potassium titanate whiskers, aluminum borate whiskers, and so forth. Meanwhile, inexpensive and high-quality inorganic whiskers such as calcium carbonate, calcium sulfate, and magnesium are successfully synthesized, which makes inorganic whiskers a new type of filling modification material of polymer materials. This field has become a research hotspot all over the world and reveals broad application and market prospects. 

PP is the most studied material in whisker reinforcing and toughening modification research. Zhou et al. studied PP modified with potassium titanate whiskers and found that the notched impact strength increased by 20% over that of pure PP. Lu et al. studied PE composite material modified with magnesium sulfate whiskers, and found that when... 

The most studied anti-wear material modified by whiskers is PEEK. Wang et al." compared the performances of PEEK before and after modification with potassium titanate whiskers. The friction and wear performances of the latter showed obvious improvement over the former. Under 300 N, the wear resistance of the latter increases 2.64 and 2.11 times than the former, respectively. In addition, calcium carbonate whiskers have an excellent anti-friction effect on PEEK composite material. When the whisker content is less than 15%, the wear rate of the material decreases dramatically. The wear rate of the... 

Shi et al. 5 also discovered that the wear resistance of PTFE improved about 300 times that of the pure PTFE after adding potassium titanate whiskers. Hu and Liang added aluminum borate whiskers and calcium sulfate whiskers respectively to bismaleimide resin and found that the wearability of both materials improved. When the content of aluminum borate whiskers was 8%, the wear rate of the material declined from 4.39 X 10" mmVCN irO to 1.42 x 10 mmV(N-m). When the content of calcium sulfate whiskers was 10%, the wear rate of the material declined from 2.89 x 10" mmy(N-m) to 1.28 x 10" mmVCN-m). Thus it can be seen that the high hardness of inorganic whiskers determines their broad application prospects in the field of polymer wear-resistant materials. 

Xin Feng, Donghui Chen, Xiaohong Jiang. Study on friction and wear properties of potassium titanate whiskers-reinforced PTFE composites. Polymer Materials Science and Engineering, 20(5) 129-132, 2004. 

Jian Zhou, Yuqi Wang, Haibin Meng. The performance of the potassium titanate whisker modified polypropylene. Engineering Plastics Application, 33(H) 21-24, 2005. 

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