Improvement of properties

The properties of commodity and engineering thermoplastics can be boosted by compounding with mineral fibres and a special compatibilizer, report two Dutch companies, Bennet BV and Lapinus Fibres BV. Polyolefins (HDPE and PP copolymer) and polyamide 6 have been successfully upgraded with 35 and 2 5% respective addition of Rockfil fibres and Bennet compatibilizer. Tests in conjunction with injection moulder Heudijk Kunststoffen BV and masterbatch producer Curver Colour Department indicated that mechanical, stability and processability properties are improved, with improved heat distortion and FR performance, good surface finish and recyclability. 

Bennet also finds that addition of its BRC 200 compatibilizer to a mixed waste stream of equal parts of LDPE, LLDPE, HDPE, VLDPE. and PP homopolymer and copolymer boosted impact strength, to higher than the single components, in injection moulded parts. Compatibilizers containing branched ethylene. EVA. and elastomers, are added to scrap LDPE, HDPE, and PP to make drainage pipes. 

Dexco (Exxon/Dow) has developed styrenic block copolymers as compatibilizers. to improve impact strength. Vector SBS (not containing halide salts) gives better heat stability than conventional block copolymers due to absence of residual halides, which can lead to property degradation. It can boost ultimate elongation and impact strength of PS waste. 

GE Specialty Chemicals supplies Blendex 338 impact modifier to upgrade ABS, SAN, and PVC. 

Rohm and Haas has targeted waste PET. which has low viscosity and poor impact strength. Dosing with EXL 5375 additive at about 20% restores properties to virgin levels. 

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Originally, these fillers were intended to play the role of extenders, in order to cut down manufacturing costs. Very soon, however, it was realized that some of them imparted unexpected properties (hardness, strength,. . . ) to the processed materials. This improvement of properties was called reinforcement. 

Four major objectives in the chemical modification of food proteins are (a) the blocking of deteriorative reactions (b) improvement of physical properties (c) improvement of properties related to acceptability, such as flavor and color and (d) improvement of nutritional properties. Modifications also may aid the physical separation from crude animal, plant, or microbial material and may inactivate or remove relatively small amounts of undesirable substances. There is considerable interest among food technologists in chemical modification as a means of changing the physical characteristics of proteins to give, e.g., better solu-... 

The modification and general improvement of properties caused by the addition of such compounds is a very interesting issue to be studied with a wide range of analytical techniques. Their identification and eventual determination is usually carried out by chromatographic techniques coupled to a variety of detection systems, most often mass spectrometry (MS). This powerful hyphenated technique, extensively used in many different analyses, combines the separation capabilities of chromatographic techniques with the potential use of MS to elucidate complicated structures and to identify many chemical compounds with low limits of detection and high sensitivities. The use of MS also permits the simultaneous detection and determination of several of those additives in a single analysis. This is especially valuable when only a small quantity of material is available, which is the usual case in some biopolymer formulations. 

The mechanism of preferentially blocking high-permeability channels is controversial (Seright, 2006 Chang et al., 2006). The research work done so far has been focused more on formulation selection, improvement of properties, and determination of factors that affect gel performance, but less on flow behavior (Ma et al., 2005). The viscoelasticity of a low concentration HPAM/ AlCit crosslinked system was mathematically described by Sun et al. (2005). 

The extraordinary mechanical, thermal and electrical properties of carbon nanotubes (CNT) have prompted intense research into a wide range of applications in structural materials, electronics, and chemical processing.Attempts have been made to develop advanced engineering materials with improved or novel properties through the incorporation of carbon nanotubes in selected matrices (polymers, metals and ceramics). But the use of carbon nanotubes to reinforce ceramic composites has not been very successful. So far, only modest improvements of properties were reported in CNTs reinforced silicon carbide and silicon nitride matrix composites, while a noticeable increase of the fracture toughness and of electrical conductivity has been achieved in CNTs reinforced alumina matrix composites. ... 

Thus Vestenamer 8012, used as a blending material, seems to offer considerable possibilities for the improvement of properties of the more common elastomers and can be expected to be used in various specialist applications wherever such improvements are critical. 

Another example of the improvement of properties of condensation polymers through copolymerization is illustrated by recent work with urea-formaldehyde (UF) resins. The preponderance of wood adhesive... 

It has been shown that the modification of CECs and epoxynovolaks with monoepoxides results in an improvement of properties of the crosslinked polymers. Under certain conditions, the monoepoxides eliminate the structural defects, thus equalizing density and increasing the mechanical strength and heat resistance [74]. 

X-rays, very common in medicine and in materials characterization, are not so frequently used for production or improvement of properties of materials and composites as the y-rays or e-beam, described earlier. The products are elemental metals in the form of nanostructures, several oxides, and salts. Thus, reductant, stabilizer-free colloidal gold solutions were fabricated by a new room-temperature synchrotron x-ray irradiation method (Yang et al 2006 Wang et al., 2007). 

Ohama, Y., Demura, K., Satoh, Y., Tachibana, K., and Endoh, T., Proceedings of the International Symposium on Admixtures for Concrete, Improvement of Properties, pp. 317-324, Chapman and Hall, London (1990)... 

A fourth type of curve for properties vs. polyblend composition representing synergistic behavior (Figure 4.40d) has been obtained in a few cases of polymer blending. This shows improvement of properties, beyond what would be expected from simple monotonic proportionality, and sometimes far exceeding the value for either polymer alone. Synergism may result from a very favorable dipole-dipole attraction between the polymer components. 

Attempts have been made to improve the mechanical properties of polymer-based materials, by adding a percentage of selected filler particles. There has been considerable improvement of properties such as elastic modulus, fracture toughness, flexural strength and hardness with the increase of the filler volume. 

Thus, polymers cured at less than 298 K based on MTI of oligoethers and two areas of mechanical losses characterize oligoester mixtures. The position of the main maximum and, consequently, Tg depends on the ratio of polymers based on simple and complex oligomers and a new area of structural transition may be referred to the loosened interphase layer. Hence, polymers of heterogeneous composition may behave as single phases in curing, which explains the improvement of properties in comparison with individual polymers. 

At present, the options for practical application of niobium and titanium oxides in electrolytic capacitors are studied as they are characterized by a high dielectric constant and lower cost than tantalum oxide. Improvement of properties of electrolytic capacitors is carried out along the following lines a significant decrease in the size of capacitors, expansion of boundaries of working temperature ranges, improvement of electric characteristics, an increase in reliability and service life of capacitors under storage and when in operation. 

Table 10.2 presents the elastic properties of phases under study. Alloying of the intermetaUic phase results in an improvement of properties. Elastic characteristics of the phases, which were calculated from first principles, increase. 

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