Stiffness flame retardants

Chem. Descrip. Ethylene-vinyl chloride copolymer latex Uses Coating binder and saturant for paper and paperboard applies. useful in heat seal adhesive appiics. or where a moisture barrier is required binder for nonwovens and textiles binder for filters, stiff flame retardant nonwovens imparts flexibility and water resist, to caulks, mastics. barrier coats in building applies., baked industrial coatings, high PVC ceiling tile coatings... 

Ultem PEI resins are amber and amorphous, with heat-distortion temperatures similar to polyethersulfone resins. Ultem resins exhibit high modulus and ate stiff yet ductile. Light transmission is low. In spite of the high use temperature, they are processible by injection mol ding, stmctural foam mol ding, or extmsion techniques at moderate pressures between 340 and 425°C. They are inherently flame retardant and generate Httie smoke dimensional stabiUties are excellent. Large flat parts such as circuit boards or hard disks for computers can be injection-molded to maintain critical dimensions. 

Polysulfone It is a high performance amorphous plastic that is tough, highly heat resistant, strong and stiff. Products are transparent and slightly clouded amber in color. Material exhibits notch sensitivity and is attacked by ketones, esters, and aromatic hydrocarbons. Other similar types in this group include polyethersulfone, polyphenyl-sulfone, and polyarylsulfone. Use includes medical equipment, solar-heating applications and other performance applications where flame retardance, autoclavability and transparency are needed. 

A variation on the THPC-urea system was developed to produce finishes with less stiffness and fibre damage (Proban process). A precondensate is prepared by the careful reaction of THPC with urea. This precondensate is padded onto the fabric and the fabric is dried to a specific moisture content ( 15 %). The fabric is then exposed to ammonia vapours in a special reaction chamber, followed by oxidation with hydrogen peroxide (Fig. 8.13). The polymer that forms is primarily located in the lumen of the cotton fibre. The final finish provides durable flame retardancy to cotton with much improved fabric properties. It is important to note... 

An important characteristic of flame retarded textiles, the "hand" or feel of the cloth, was satisfactory it did not become stiff. Similar results were obtained when padding cotton flannel... 

Wollastonite is not yet used in commercial WPC materials, but it is currently under investigation to further enhance the properties of WPCs. The mineral is used worldwide in many plastic applications providing improvement in stiffness, impact, scratch resistance, lower thermal coefficient of expansion-contraction, and flame retardancy. The unique morphology of wollastonite and the variety size grades available can provide benefits that are not obtained by other minerals. In a number of cases, wollastonite has successfully replaced talc in plastic applications where further improvements in properties such as greater strength and improved scratch resistance were required. 

A common disadvantage of chlorine-containing flame retardants is that they have to be added in quantities, which in turn decrease mechanical properties of the polymer materials. The same sitnation in terms of large amount that should be added into the base material holds for mineral flame retardants as well (ATH, Mg(OH)2) however, minerals typically improve both flexural modulus (stiffness) and flexural strength of composites. 

Reasons for use abrasion resistance, cost reduction, electric conductivity (metal fibers, carbon fibers, carbon black), EMI shielding (metal and carbon fibers), electric resistivity (mica), flame retarding properties (aluminum hydroxide, antimony trioxide, magnesium hydroxide), impact resistance improvement (small particle size calcium carbonate), improvement of radiation stability (zeolite), increase of density, increase of flexural modulus, impact strength, and stiffness (talc), nucleating agent for bubble formation, permeability (mica), smoke suppression (magnesium hydroxide), thermal stabilization (calcium carbonate), wear resistance (aluminum oxide, silica carbide, wollastonite)... 

With the advent of nanocomposites, notions about how to cost-effectively reinforce resins may change. As with fiber-filled PP, the issues of stiffness and strength vs. weight and cost could be key questions for nanocomposites, which require only low loadings (3%-5%) of nanofillers to maximize properties. Since resin makes up most of the balance of these composite systems, a cost-conscious user of a PP nanocomposite would likely seek to minimize product thickness. Otherwise, other value-adding properties of a nanofiller (such as charge dissipation, flame retardancy, or barrier properties) may also help it to compensate for its extra material and processing costs [8-12]. 

The addition of rigid particles into the polyolefin matrix can result in a number of desirable effects on the composite including increased stiffness, improved flame retardancy, and enhanced electrical properties. 

Lin and co-workers [51] observed that cnring phenolic resins with epoxies instead of with hexamethylene tetramine yields polymers which have almost the same flame retardance as polymers produced with hexamethylene tetramine curing. They also have toughness, stiffness, good thermal stability, excellent flame retardance and low glass transition temperature (Tg). 

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