Fillers heat stability

Of the various chemical classes of UV stabilizers that have been developed, the benzophenone and benzotriazole UV absorbers, the hindered amine light stabilizers (HALS), and their combinations continue to satisfy the UV stabilization requirements of most of the large-volume outdoor polymer applications. In addition, many new stabilizer chemistries, such as UV absorbers based on hydrox-yphenyl triazines, have been developed for more demanding applications or to satisfy specific market needs. Light stabilizers together with other additives (qv), such as antioxidants (qv), impact modifiers, colorants (qv), fillers, heat stabilizers (qv) and plasticizers (qv), have enhanced the properties and extended the service life of polymeric materials, resulting in the replacement of traditional materials in a multitude of outdoor weatherable applications. 

Plastics and Resins. Plastics and resin materials are high molecular weight polymers which at some stage in their manufacture can be shaped or otherwise processed by appHcation of heat and pressure. Some 40—50 basic types of plastics and resins are available commercially, but HteraHy thousands of different mixtures (compounds) are made by the addition of plasticizers, fillers, extenders, stabilizers, coloring agents, etc. 

Other contaminants that can originate from plastic containers are the additives necessary to turn the raw polymer into adequate containers. While PE may be used without any additive, the other plastics are virtually useless alone but are converted into highly serviceable products by combining them with other substances or materials. The additives most commonly found in plastics used for pharmaceutical products are antioxidants, heat stabilizers, lubricants, plasticizers, fillers, and colorants. These additives can be in liquid, solid, or fine particle forms and are used in amounts varying from less than 1% to more than 50% of the plastic mass. The additives necessary for each of the selected types of polymers are described in Table 23. 

Differences between the ingredients in a formulation may be essentially of a chemical nature, but also may be physical (such as the ranges of particle sizes)—and quite often both chemical and physical variations are found in practice. In order to match a particular material consistently it is not sufficient merely to know even the precise formulation in terms of polymer, plasticizer, heat stabilizer, filler, anti-static agent, colour, and so forth each of the components in the formulation must be supplied consistently to a tight... 

To meet specific needs, other additives such as lubricants, extenders, fillers, impact modifiers, and pigments are added to the PVC compound, in addition to heat stabilizers and plasticizers. Today, it is estimated that more than 60% of all the adducts used in plastics are used in PVC compounds. Although the earliest PVC compounds were produced as emulsions, essentially all PVC compounds are produced today as suspensions. Suspension compounds contain essentially no emulsifiers and are more processable. Liquid plastisols typically have room-temperature viscosities of less than 10,000 cp. Products made from plastisols are usually very soft. They have Shore Durometers of 55A and less, to as low as 30A, and they can have characteristic skin- or leather-like appearance and feel. 

Other Plastics Uses. The plasticizer range alcohols have a number of other uses in plastics liexanol and 2-ethylliexanol are used as part of the catalyst system in the polymerization of acrylates, ethylene, and propylene (55) the peroxydicarbonate of 2-ethylliexanol is utilized as a polymerization initiator for vinyl chloride various trialkyl phosphites find usage as heat and light stabilizers for plastics organotin derivatives are used as heat stabilizers for PVC octanol improves the compatibility of calcium carbonate filler in various plastics 2-ethylliexanol is used to make expanded polystyrene beads (56) and acrylate esters serve as pressure sensitive adhesives. 

The variety of substances used as additives in polymers is considerable. For example, the fillers may include china clay, various forms of calcium carbonate, talc, silicas (diatomaceous silica), silicates, carbon black, etc. The impact modifiers typically include other polymers. Plasticizers include certain polymers with low (oligomers), dialkyl phthalates, dialkyl sebacates, chlorinated paraffin waxes, liquid paraffinic fractions, oil extracts, etc. Heat stabilizers include heavy metals salts such as basic lead carbonate, basic lead sulfate, dibasic lead phosphite (also acting as a light stabilizer), dibasic lead phthalate, stearates, ricinoleates, palmitates and octanoates of cadmium and barium, epoxide resins and oils, amines, diphenylurea, 2-phenylindole, aminocrotonates. The antioxidants include tris-nonyl phenyl phosphite, 2,6-di-ferf-butyl-p-cresol (BHT), octadecyl-3,5-di-terf-butyl-4-hydroxyhydrocinnamate, etc. The UV stabilizers include modified benzophenones and benzotriazoles. Processing lubricants include calcium stearate, stearic acid, lead stearate, various wax derivatives, glyceryl esters and long-chain acids. Fire retardants include antimony oxide, some pyrophosphates, etc. 

Fillers are used frequently with solvent vinyl systems in order to lower cost. Increase hiding power of the coating, and increase the total solids of the system. They may detract from ultimate durability due to impurities that are present in the filler. This may manifest itself as poor light stability or film porosity due to water-soluble ingredients present. Basic ingredients may be reactive with carboxyl-containing (metal adhesion type) resins. Iron contamination may cause poor light and heat stability of the system. 

Effects of the additives specifically applied to stabilize polymers e.g., antioxidants, hydroperoxide decomposers, light and heat stabilizers) have been already discussed. Fillers, reinforcements, pigments, plasticizers and lubricants may affect the processability, but usually do not influence the stabilization strategy. Owing to different chemical characters some flame retardants and dyes may... 

The filler then contributes to reinforcement, thixotropy, and bulk. Since most of the fillers are mineral-like inorganic materials, they generally don t add or detract from the intrinsic silicone properties for which the sealants are most often sold, such as good electrical insulating properties, weather resistance, heat stability and low temperature serviceability. Organic fillers (polymers, resins, rubbers) have been added to some silicones and indeed enhance certain properties or reduce cost but always at the expense of another property. The property most often sacrificed is thermal stability. 

The number and amount of additives incorporated in a resin vary with resin type and application. A polyethylene resin, for instance, may have only an antioxidant incorporated, or a colorant may also be added. A PVC resin may require several plasticizers, a filler, a heat stabilizer, and a colorant. There are many variations, and in most cases, the final resin formulation is considered by the manufacturer to be proprietary information. A confidentiality agreement may be necessary to make certain that the material meets regulatory compliance, unless the supplier can give the end-user sufficient information to make the determination. 

Although the primary purpose of this chapter is to discuss mechanical testing and strength of adhesive joints, the reader should be aware that ASTM covers a wide variety of tests to measure other properties. ASTM, for example, includes standard tests to measure the viscosity of uncured adhesives, density of liquid adhesive components, nonvolatile content of adhesives, filler content, extent of water absorption, stress cracking of plastics by liquid adhesives, odor, heat stability of hot-melt adhesives, ash content, and similar properties or features of adhesives. 

The combination of poly(arylene ether) (PAE) resins with PAs into com-patibilized blends results in improved overall properties, such as chemical resistance and high strength. The properties of these blends can be further enhanced by the addition of various additives, such as impact modifiers, flame retardants, light stabilizers, processing stabilizers, heat stabilizers, antioxidants and fillers. 

A main line of development continuing today is multifunctional additives, such as fillers, which are treated to provide also a degree of reinforcement. For example, calcium carbonate improves surface gloss of PVC, talc is added to PP to improve stiffness and heat stability. An essential aspect is the compatibility with the resin matrix and there is intense development of surface-modification technology, to render fillers of all types more acceptable to the matrix. 

Compounding Additives, fillers, and/or reinforcements are mixed with polymers (referred to as plastics) providing different properties and/or different fabricating methods for plastics. Hundreds of different materials are used such as heat stabilizers, color pigments, antioxidants, inhibitors, and fire retardants. 

Long-term heat-aging effects of heat stabilizers. Along with melt-processing stability, different AO formulations and concentrations can extend the useful lifetimes of heat-exposed products well past that of unstabilized base HOPE. If fillers such as carbon black are added, heat-resistance to embrittlement may be extended even longer. 

Problem Nanoclay fillers interact negatively with standard heat stabilizers. 

Henschel mixer is most frequently used for dryblending. " In such a mixer, the technological process includes addition steps and temperatures which must be reached in order to proceed to the next step. Order of addition is considered important. The following order of addition is usually suggested resin, stabilizer, plasticizer, filler, lubricant. Stabilizer is added to the resin before it is subjected to heat, and lubricant is added at the end because it may interfere with plasticizer absorption. - Temperatures which determine the end of the mixing step depend on the amount of plasticizer in a mixture (the higher the amount of plasticizer, the higher the temperature). Final temperature of dryblend is between 90 and 110°C. Premixed dry blend is then cooled to below 50°C. ... 

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