Additives particulate

The only information that provided an assessment of exposure of children and adolescents to hydrogen sulfide was that developed during the South Karelia Air Pollution Study (Mortilla et al. 1994b) however, these exposures were complicated by simultaneous exposure to other sulfur-containing compounds as well as particulates. Additional exposure information is needed from communities where only hydrogen sulfide exceeds background levels. 

Visualising and detecting different elements in particulate additives or contaminants... 

The effect of particulate additives on the appearance of polymers is a complex subject depending, among other things, on the colour, refractive index, particle... 

C. R. Blanchard and R. A. Page, Effect of Silicon Carbide Whisker and Titanium Carbide Particulate Additions on the Friction and Wear Behavior of Silicon Nitride, J. Am. Ceram. Soc., 73[11], 3442-3452 (1990). 

NTP (0.08) and 1-NPer (0.08). These values were lower than that of 1-NP whose concentration was the highest in the atmospheric particulates. Additionally, several compounds of these nine NPAHs, such as 3-NBA and 2-NTP, show very strong... 

For particulate additives, the term filler is still widely used (reflecting the original and continuing need to add bulk to the mix to reduce the cost). An important aspect of the development of even low-cost additive fillers, however, is surface treatment of particles to aid bonding to the matrix and offer positive mechanical advantages as well as sheer bulk. 

Filler—A relatively inert substance added to a material to alter its physical, mechanical, thermal, electrical or other properties or to lower cost. Sometimes the term is used specifically to mean particulate additives. 

Platelet additives may impart color and luster, metallic appearance, or a pearlescent effeet and also can strongly affect permeation properties. Most of these additives have little or no permeation through them, so when a film contains particulate additives, the permeating molecule must follow a path around the particulate additive as shown in Figure 1.19. This is often called a tortuous path effect. 

Permanent antistatic properties can be readily obtained with such particulate materials as carbon black. However, these materials are inappropriate for applications where color and/or transparency capability is important. Also, particulate additives can negatively affect the physical properties of the final part and contribute to contamination in electronic applications also known as sloughing. 

Hyperion Catalysis International markets its nanombes under the name Fibril . Adding 5% to polycarbonate transforms its volume resistivity from lO to 10 ohm-cm and, unlike some particulate additives, only reduces the tensile strength by 11%, while increasing the flexural modulus by 18%. One important application is the polyamide fuel lines in vehicles, and another is the production of the conductive thermoplastic fenders used for in-line electrostatic painting. In the case of fuel lines, the compounding system must produce highly homogeneous compositions to rule out local static build up. Less than one per cent of nanotubes is sufficient. 

Lower part warpage. Nanoparticles are much smaller than other particulate additives, thus are more insensitive to shear. The random distribution results in a reduced chance of part warpage. 

With this wide range of material types and approaches to compounding, incorporation of particulate additives into polymers can vary greatly from one compoimd to another. Attention will therefore be directed only on the main types of compoimding plant used industrially, highlighting their principles of design and operation specifically for the preparation of particulate-filled polymeric compositions. 

High-intensity non-fluxing batch mixers are frequently used in the preparation of PVC dry-blends, which may contain appreciable quantities of particulate additives and liqnid plasticisers [22]. 

High-speed mixers can also be an extremely effective means of pre-blending powder forms of polymer (other than PVC), with particulate additives, such as pigments or mineral fillers. The action is essentially one of inter-particle randomisation. It is questionable... 

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