Improvement of mechanical properties

In concrete, triethanolamine accelerates set time and increases early set strength (41—43). These ate often formulated as admixtures (44), for later addition to the concrete mixtures. Compared to calcium chloride, another common set accelerator, triethanolamine is less corrosive to steel-reinforcing materials, and gives a concrete that is more resistant to creep under stress (45). Triethanolamine can also neutralize any acid in the concrete and forms a salt with chlorides. Improvement of mechanical properties, whiteness, and more even distribution of iron impurities in the mixture of portland cements, can be effected by addition of 2% triethanolamine (46). Triethanolamine bottoms and alkanolamine soaps can also be used in these type appUcations. Waterproofing or sealing concrete can be accompUshed by using formulations containing triethanolamine (47,48). 

Alpha—beta aluminum alloys respond to heat treatment with a general improvement of mechanical properties. Heat treatment is accompHshed by heating to 815—870°C, quenching in water, and reannealing at 370—535°C, depending on the size and section of the casting. Different combinations of strength, hardness, and ductility can be obtained. Some nickel in aluminum bronze is in soHd solution with the matrix and helps refine the precipitate, and a smaller amount is in the K-intermetaUic compound. 

Construction Soil stabilization water absorber water retention aids in cements, grouts, and tiles improvement of mechanical properties of cement and gypsum plasters and water based paints... 

Li, S., Lamminmaki, J., and Hanhi, K., Improvement of mechanical properties of rubber compounds using waste rubber/virgin rubber, Polym. Eng. Sci., 45, 1239, 2005. 

The use of irradiated PTFE powder in EPDM gives enhanced mechanical properties as compared to composites containing nonirradiated PTFE. The existence of compatibility between modified PTFE powder and EPDM is indirectly revealed by , DSC, and SEM. shows that modified PTFE powder (500 kGy-irradiated) is obviously but partially enwrapped by EPDM as compared to nonirradiated PTFE powder. This leads to a characteristic compatible interphase around the modified PTFE. The resultant chemically coupled PTFE-filled EPDM demonstrates exceptionally enhanced mechanical properties. Crystallization studies by DSC also reveal the existence of a compatible interphase in the modified-PTFE-coupled EPDM. The synergistic effect of enhanced compatibility by chemical coupling and microdispersion of PTFE agglomerates results in improvement of mechanical properties of PTFE-coupled EPDM compounds. In summary, an effective procedure both for the modification of PTFE powder as well as for the crosslinking of PTFE-filled EPDM by electron treatment has been developed for the preparation of PTFE-coupled EPDM compounds with desired properties. 

In low melting point metal dispersed systems, the Al203/Ni system has been studied to obtain the desired microstructure and improvement of mechanical properties by modification of the microstructure. Moreover, considering the magnetic properties of the composites, it was expected to improve both mechanical and magnetic properties by incorporating merely nanometer-sized Ni, Co, and Fe into an A1203 matrix. 

As carbon nanotubes present exceptional mechanical, superior thermal and electrical properties in general, by using them as reinforcing elements there are high expectations for improvement of quality of nano- and microcomposites [14-18]. As shown from earlier measurements, through carbon nanotube addition a 15-37% improvement of mechanical properties (elastic modulus and strength) can be achieved in comparison to other carbon-filled samples [19]. 

Reinforcement of elastomers by colloidal fillers, like carbon black or silica, plays an important role in the improvement of mechanical properties of high performance rubber materials. The reinforcing potential is mainly attributed to two effects ... 

Stretchability denotes the suitability of a polymer in the solid state (amorphous or semicrystalline) to be stretched in one direction (occasionally in two directions). Of course, this processing step only serves a useful purpose in a specimen with a large aspect (i.e. length to diameter) ratio (fibres, films, sheets). The purpose of this operation generally is to achieve an improvement of mechanical properties, especially in the direction of stretching. 

Nanotube functionalization is performed in other examples listed in Table 11.1. In 1999, Shaffer et al. used carboxylated MWNTs. By contrast to studies described in the followings, this allows to the achievement of homogeneous composites with a large nanotube fraction of about 50 wt%. However, the improvement of the Young s modulus is still weak, particularly if we consider the large amount of CNTs included in the matrix. Liu et al. (47) reported an improvement of mechanical properties with SWNTs which are covalently functionalized by OH groups, compared to the same neat nanotubes simply dispersed with SDS. 

A large number of macroscopic properties of elastomer networks are closely related to the density of network junctions and the extent of their fluctuations. Qualitatively, any increase of network density causes an increase in stress, whereas fluctuations of network junctions leads to a decreasing stress. It is generally believed that a formation of additional network junctions resulting fi-om the presence of filler particles in the elastomer matrix is one of the reasons for the improvement of mechanical properties of filled elastomers. However, the application of macroscopic techniques does not provide reliable results for the network structure in filled elastomers. Furthermore, a lack of information exists on the dynamic behavior of adsorption junctions. The present study fills the gap of knowledge in this area. 

Considerable effort has been spent to explain the effect of reinforcement of elastomers by active fillers. Apparently, several factors contribute to the property improvements for filled elastomers such as, e.g., elastomer-filler and filler-filler interactions, aggregation of filler particles, network structure composed of different types of junctions, an increase of the intrinsic chain deformation in the elastomer matrix compared with that of macroscopic strain and some others factors [39-44]. The author does not pretend to provide a comprehensive explanation of the effect of reinforcement. One way of looking at the reinforcement phenomenon is given below. An attempt is made to find qualitative relations between some mechanical properties of filled PDMS on the one hand and properties of the host matrix, i.e., chain dynamics in the adsorption layer and network structure in the elastomer phase outside the adsorption layer, on the other hand. The influence of filler-filler interactions is also of importance for the improvement of mechanical properties of silicon rubbers (especially at low deformation), but is not included in the present paper. 

Improvement of Mechanical Properties Observed for the Ceramic Nanocomposites... 

Carbon fiber PEEK polyimide no improvement of mechanical properties 52... 

The above review of current findings shows that polymer blending in the presence of fillers may offer interesting new products. Considerable effort was made in the studies of conductive polymers, and many valuable practical results are available. The effect of fillers on the improvement of mechanical properties is still on the exploratory stage. At the same time, numerous theoretical possibilities exist which should contribute to improved materials in the future. 

Ji JY et al (2009) Significant improvement of mechanical properties observed in highly aligned carbon-nanotube-reinforced nanolibers. J Phys Chem C 113(12) 4779 785... 

Improvement of Mechanical Properties. The most important application of SAS, and one of the oldest, is the control of the mechanical properties of rubber. SAS are important additives for both styrene-butadiene rubber (SBR) and natural rubber (NR), second in importance only to carbon black (51, 52). Figure 5 demonstrates the increase in tensile strength at room temperature for silicone rubber with various reinforcing fillers and kieselguhr. An improvement is also brought about in the mechanical strength of fluoroelastomers and other special kinds of rubber (51). Table VI summarizes the improvements that may be achieved in other fields. 

Improving of mechanical properties of WPC. Of course, other properties of WPC were recognized as important ones, but mechanical properties always were considered as key properties for building, construction materials, such as deck boards. 

Binary blends of iPP and EPR copolymers have been extensively investigated from the commercial point of view. Although the control of compatibility plays an important role in the improvement of mechanical properties in the iPP/EPR blend systems, the strong incompatibility in iPP and EPR blends limits the modifications of morphology and mechanical properties (9). 

Compatibilizers have a key role in improving the compatibility between the blend components and thereby enhancing the mechanical properties. Several reports are available in connection with improving the properties of NR/EPDM blends by compatibilization. George et al. (67) has reported on the improvement of mechanical properties of NR/EPDM blends by precuring EPDM prior to blending. Blends of... 

The addition of plasticizer used for the improvement of mechanical properties leads generally to an increase in the oxygen permeability coefficient due to the higher mobility of the polymer chain and higher free volume [102]. On the contrary, the dispersion of nanoclays in PLA makes it possible to divide the permeability coefficient by 2 or 3 depending upon the type of the nanoclays (e.g. organomodified montmorillonite, cloisite 25A or 30B, organomodified synthetic fluorine mica) and exfoliation [129-131]. 

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