Polyamide primary applications

PDBS-80 was the first in the series. This material is a homopolymer of dibromostyrene that contains 59-60% bromine. Its primary applications are in high-temperature polyamides and polyethylene terephthalate (PET) because it has excellent flow characteristics and very good thermal stability. In addition, there are benefits of excellent colour retention. The main weakness of this approach is the bromine content relative to the competitive material. Today s competition contains around 68% bromine. This can translate into a 2-3 parts difference in the load level needed in the protected polymer to give equivalent flame retardancy. 

Early hot melt adhesives were based on ethyl cellulose and animal or hide glues. These were later replaced by synthetic resins such as polyamides and ethylene-vinyl acetate copolymers. More recently a new class of compounds, referred to as block copolymers because of their unique chemical structure, have emerged. These latter compounds are copolymers of styrene and butadiene, isoprene, or ethylene-butylene which tend to widen the flexibility property range of hot melt adhesives. They probably represent the fastest growing segment of the hot melt adhesives market at the present time. Their primary application is in hot melt pressure sensitive adhesives. Polymers based on other than polyolefin resins are discussed in other chapters in this handbook. 

Typical automotive applications include gas cap covers, fan blades, shrouds for cooling systems, gears, fasteners, clips, emission control canisters, oil pans, shields, etc. Toughened polyamides are also used in sports and recreational equipment, lawn and power tool housings and components where impact strength, heat and chemical resistance are the primary criteria for their choice. With an estimated consumption of 25 Mton/y in the USA, impact modified PAs... 

Fatty bisamides are used primarily to increase slip, reduce blockiog, and reduce static in polymeric systems. Other specialty appHcations include cosolvents or coupling agents for polyamide resins, fillers for electrical insulation coatings, additives for asphalt to reduce cold flow, and synthetic waxes for textile treatments (68). Bisamides have been used in all the traditional primary amide applications to increase lubricity and have become the amide of choice because of their better efficiency. Bisamides have the highest commercial value in the amide market. 

Hot melts—100% soUds adhesives that are heated to produce a workable material—are based on polyethylene, saturated polyester or polyamide in chunk, granule, pellet, rope, or slug form. Saturated polyesters are the primary hot melts for plastics the polyethylenes are largely used in packaging polyamides are used most widely in the shoe industry. Application speeds of hot melts are high and it pays to consider hot melts if production requirements are correspondingly high. 

Inherently FR polyamide fibres. Nylon or polyamide 6.6 has a higher melting point and superior tensile properties to polyamide 6 and so has the better characteristics to offer technical textiles. However, and in spite of the considerable research over the last 40 years, at the present time only one flame retardant polyamide 6.6 appears to available, which is Nexylon FR, EMS-GRILTECH of unknown composition, announced in September 2012. This fusible fibre is currently being aimed at the protective clothing and workwear markets but such applications will require flame retardancy as their primary property rather than heat protection. 

The polyamide-imide achieved at the end of this process is a high-molecular-weight, fully imidized polymer in solvent with no condensation by-products, since the carbon dioxide gas is easily removed. This convenient form makes it especially beneficial for the manufacturer where the primary end use is wire enamel or another coating application. The solution viscosity is thus controlled by stoichiometry, monofunctional reagents, and polymer solids. The typical polymer sohds level is 35 to 45% and it may be diluted further by the supplier or customer with diluents. 

Blends of primary anti-oxidants and a high-temperature hydrolytically stable organophosphite secondary anti-oxidant have been developed for high-temperature processing of polyolefins, polyamides, and polycarbonates in colour-critical applications. Irganox LM blends of primary anti-oxidants and a new phosphite processing stabilizer offer melting at 90°C and can be applied to polymer reactor products, especially polyolefins, linear polyesters, polycarbonates, polyamides, HIPS, ABS, SAN, and elastomers. 

The polymer applications of wollastonite are mainly based on its combination of acicularity, chemical inertness, whiteness and low water adsorption. Primary consuming polymers include thermoplastics, such as polypropylenes and polyamides, and thermosets, snch as polyester dough and sheet-moulding compounds, epoxies and phenolics. Manufacturers are predicting considerable growth in reinforced reaction injection moulding (RRIM) systems. 

SBS and SEBS block copolymers have been employed to impact modify HIPS, PPO/HIPS and various polyolefins. Maleic anhydride modified SEBS offers impact modification of polyamides and polyesters via reactive compatibilization. Chlorinated polyethylene (< 42 wt% Cl) is employed as an impact modifier for PVC, where weatherability is a primary concern [121]. Ethylene-(meth)acrylic acid copolymers and their neutralized versions (ionomers) have been utilized as impact modifiers for polyamides. PBT and PET impact modification with the poly(ester-ether block copolymer) (PBT-poly(tetramethylene oxide) (AB) ) yielded utility in automotive fascia applications. These products have been available under the tradenames Lomod (GE), Bexloy (duPont) andRiteflex (Hoechst-Celanese) [3]. 

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