Additives polymers

Additives are essential components of plastic formulations that provide maintenance and/or modification of polymer properties, performance, and long-term use. The extension of polymer properties by additives has been playing a substantial role in the growth of plastics, and many polymer applications are accessible only in the presence of a number of ingredients, often only in small quantities, in addition to the polymer itself. 

Additives embrace a wide area of different chemical structures used in plastics for many different purposes 

The consumption of polymer additives today is estimated in the range of 5000 kt (kilotons) corresponding to a value 

Handbook of Polymer Synthesis, Characterization, and Processing, First Edition. Edited by Enrique Saldivar-Guerra and Eduardo Vivaldo-Lima. 2013 John Wiley Sons, Inc. Published 2013 by John Wiley Sons, Inc. 

In the following part, the most important classes of additives (antioxidants, PVC heat stabilizers, light stabilizers, and flame retardants) are presented, as well as general information on chemical structures and mechanisms, on testing methods, and on use examples in selected polymer 

The analysis of additives in polymers has been reviewed by several workers [1, 2]. A variety of analytical techniques have been considered. 

The possibilities of SFC for determining polymer additives have been demonstrated [118-129]. The low elution temperature and high resolution of capillary fluid chromatography makes this technique very attractive. Other advantages are that a FID can be used and that interfacing with spectroscopic detectors is somewhat easier than with HPLC. Quantitation in capillary SFC has been found to be more difficult than in HPLC and capillary GC, however, because of lack of precision in injection [40]. 

Long-term properties of polymers are severely affected and the service-life is reduced due to the migration of additives. There is also the possibility that some of the additives accumulate in the environment and affect our health and the environment. SPME has been applied for the extraction of several common polymer additives. Since additives often have rather low volatility, a significant advantage with SPME and HS-SPME compared to HS-GC-MS is the ability to extract even semi-volatile compounds [9,13]. 

This is an extremely important area. Commercial polymers are very rarely prepared or used without additives and they often contain a combination of additives. These improve processability of the polymer, its durability, service life under adverse conditions (e.g., temperature, UV light and various chemical environments), strength (e.g., using reinforcing fillers), appearance (colorants), etc. A recent use of additives is to facilitate reprocessing or recycling or, alternatively, to promote decomposition (which is often difficult because the stability is inherent in the polymer s chemical structure). (The analysis of additives in polymers is the subject of Chapter 14.) 

Polymer additives may be classified into five groups (although some additives can serve more than one purpose, e.g., plasticisers, carbon black)  

The total world demand for additives is ca. 2 million tonnes per annum (excluding fillers and colorants — with fillers this becomes 20 million tonnes per 

The additives can be added during the polymerisation (either in the form of a reactive monomer or as an inert material — advantages include better dispersion and increased retention), but they are usually added immediately postpolymerisation of the polymer and extruded with the polymer. Often a concentrated mix with the plastic (master-batch) is prepared by the plastic manufacturer and this can be sold to the fabricators to be added during subsequent processing. 

When using additives the following precautions should be taken  

Although the properties of polymers may be fine-tuned based on the functional groups that are present in their repeat units, all commodity polymers also contain a number of components in order to impart desired properties. Some common additives include  

As their name implies, plasticizers are additives that soften a material, enhancing its flexibility. The worldwide market for plasticizers is currently over five million metric tons, with over 90% used to soften PVC. The most common plasticizers are phthalates however, due to the relatively high vapor pressure of these compounds, plasticizers will evaporate from the polymer structure as evidenced by the new car smell of new cars, as well as the organic film that becomes deposited on the interior windshield surface. For these applications, it is best to use a plasticizer with a lower volatility such as trimellitates. 

There are two leading theories concerning the mechanism of activity for plasticizer molecules. The Tubricating theory suggests that as the polymer is heated, the plasticizer diffuses into the polymer and disrupts the van der Waal interactions 

Most of the properties of polymers discussed earlier in this chapter are intrinsic ones— that is, they are characteristic of or fundamental to the specific polymer. Some of these properties are related to and controlled by the molecular structure. Often, however, it is necessary to modify the mechanical, chemical, and physical properties to a much greater degree than is possible by the simple alteration of this fundamental molecular structure. Foreign substances called additives are intentionally introduced to enhance or modify many of these properties and thus render a polymer more serviceable. Typical additives include filler materials, plasticizers, stabilizers, colorants, and flame retardants. 

Filler materials are most often added to polymers to improve tensile and compressive strengths, abrasion resistance, toughness, dimensional and thermal stability, and other 

Some polymeric materials, under normal environmental conditions, are subject to rapid deterioration, generally in terms of mechanical integrity. Additives that counteract deteriorative processes are called stabilizers. 

One common form of deterioration results from exposure to light [in particular, ultraviolet (UV) radiation]. Ultraviolet radiation interacts with and causes a severance of some of the covalent bonds along the molecular chains, which may also result in some crosslinking. There are two primary approaches to UV stabilization. The first is to add a UV-absorbent material, often as a thin layer at the surface. This essentially acts as a sunscreen and blocks out the UV radiation before it can penetrate into and damage the polymer. The second approach is to add materials that react with the bonds broken by UV radiation before they can participate in other reactions that lead to additional polymer damage. 

Another important type of deterioration is oxidation (Section 17.12). It is a consequence of the chemical interaction between oxygen [as either diatomic oxygen (O2) or ozone (O3)] and the polymer molecules. Stabilizers that protect against oxidation consume oxygen before it reaches the polymer and/or prevent the occurrence of oxidation reactions that would further damage the material. 

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One problem facing engineers in this situation, where the process is applied from waterflood initiation, is how to quantify the incremental recovery resulting from the polymer additive. 

Polymers can be classified as addition polymers and condensation polymers. Addition polymers are formed by iiitermolecular reactions of the monomeric units without the elimination of atoms or groups. An example is vinyl chloride, which can be made to combine with itself to yield polyvinyl chloride ... 

Polymer additives Polymer alloys Polymer analysis... 

Current manufacturers of these products are the Polymer Additives Group of Witco Corp. (New York), with the trade name Mark, and Synthetic Products Co. (Cleveland), with the trade name Synpron. The antimony-based stabilizers are typicaHy used for rigid PVC extmsion appHcations at about 0.4 to about 0.8 phr, priced at about 3.80— 4.50/kg. 

Materials. For holographic information storage, materials are required which alter their index of refraction locally by spotwise illumination with light. Suitable are photorefractive inorganic crystals, eg, LiNbO, BaTiO, LiTaO, and Bq2 i02Q. Also suitable are photorefractive ferroelectric polymers like poly(vinyhdene fluoride-i o-trifluorethylene) (PVDF/TFE). Preferably transparent polymers are used which contain approximately 10% of monomeric material (so-called photopolymers, photothermoplasts). These polymers additionally contain different initiators, photoinitiators, and photosensitizers. 

Fig. 13. Thickening of lOW base stock to multigraded oil with polymer additives. A, high mol wt poly(alkyl methacrylate) B, low mol wt poly(aLkyl...

Poly(methyl methacrylate) and poly(vinyl acetate) precipitate from the resin solution as it cures. This mechanism offsets the contraction in volume as the polyester resin cross-links, resulting in a nonshrinking thermoset. Other polymer additives such as poly(butylene adipate) provide similar shrinkage... 

The neat resin preparation for PPS is quite compHcated, despite the fact that the overall polymerization reaction appears to be simple. Several commercial PPS polymerization processes that feature some steps in common have been described (1,2). At least three different mechanisms have been pubUshed in an attempt to describe the basic reaction of a sodium sulfide equivalent and -dichlorobenzene these are S Ar (13,16,19), radical cation (20,21), and Buimett s (22) Sj l radical anion (23—25) mechanisms. The benzyne mechanism was ruled out (16) based on the observation that the para-substitution pattern of the monomer, -dichlorobenzene, is retained in the repeating unit of the polymer. Demonstration that the step-growth polymerization of sodium sulfide and /)-dichlorohenzene proceeds via the S Ar mechanism is fairly recent (1991) (26). Eurther complexity in the polymerization is the incorporation of comonomers that alter the polymer stmcture, thereby modifying the properties of the polymer. Additionally, post-polymerization treatments can be utilized, which modify the properties of the polymer. Preparation of the neat resin is an area of significant latitude and extreme importance for the end user. 

The production of alkylphenols exceeds 450,000 t/yr on a worldwide basis. Alkylphenols of greatest commercial importance have alkyl groups ranging in size from one to twelve carbons. The direct use of alkylphenols is limited to a few minor appUcations such as epoxy-curing catalysts and biocides. The vast majority of alkylphenols are used to synthesize derivatives which have appUcations ranging from surfactants to pharmaceuticals. The four principal markets are nonionic surfactants, phenoUc resins, polymer additives, and agrochemicals. 

Nonionic surfactants and phenoUc resins based on alkylphenols are mature markets and only moderate growth in these derivatives is expected. Concerns over the biodegradabiUty and toxicity of these alkylphenol derivatives to aquatic species may limit their use in the future. The use of alkylphenols in the production of both polymer additives and monomers for engineering plastics is expected to show above average growth as plastics continue to replace traditional building materials. 

Flame Retardants. Bromine compounds make up an important segment of the market for flame retardants used in polymers. Additive flame retardants are added to polymers during processing reactive flame retardants react chemically to become part of the polymer chain itself. In addition to the compounds Hsted in Table 3, a number of proprietary mixtures and phosphoms—bromine-containing flame retardants are also sold (see Elame RETARDANTS, HALOGENATED, FLAAffi RETARDANTS). 

Paint Driers and Polymer Additives. Paints based on alkyd resins (qv) dry by the oxidation and cross-linking of unsaturated side chains. Metal catalysts are included in paint formulations to promote this drying. Cerium carboxylates, eg, the naphthenate, are used as through driers, ie, to promote drying in the body of the paint film rather than at the film s surface (44). 

Since the dryer is a batch-operating unit, it is commonly used in the pharmaceutical industiy to maintain batch identification. In addition to pharmaceutical materials, the conical mixer diyer is used to dry polymers, additives, inorganic salts, and many other specialty chemicals. 

Removal of particles from liquid, as with polymer additives which induce clay flocculation. 

There are different concrete replacement systems available for renovating reinforced concrete structures. They range from sprayed concrete without polymer additions to systems containing conducting polymers (PCC-mortar). Since with the latter alkalinity is lower, more rapid carbonization occurs on weathering [59] and the increased electrical resistivity has to be taken into account, so that with cathodic protection only sprayed concrete should be used as a repair mortar. 

Polymer compounds vary considerably in the amount of heat required to bring them up to processing temperatures. These differences arise not so much as a result of differing processing temperatures but because of different specific heats. Crystalline polymers additionally have a latent heat of fusion of the crystalline structure which has to be taken into account. 

For many purposes these limitations are not serious whilst in other eases the correct choice of polymer, additives, processing conditions and after-treatment can help considerably. 

Represents more than 400 manufacturers of polymers, additives, and machinery as well as all types of plastics processors and fabricators. Membership is divided into 15 Business Groups sharing four Market Sector Groups. 

Figure 13.21 shows the resolution of a dozen polymer additives at very high resolution using chloroform as the mobile phase. Tinuvin 622 will elute in pure chloroform whereas Chimassorb 944 and many other hindered amine light stabilizers (HALS) will not. With the addition of 1% triethyl amine to the chloroform, however, virtually all HALS will elute. 

FIGURE 13.21 A series of polymer additives using the infrared detector at 5.78 micron. Efficiencies were calculated using the last peak, Tinuvin P, and a plate count of 290,000 was achieved. 

In this present chapter, the applications of multidimensional chromatography using various types of coupled techniques for the analysis of industrial and polymer samples, and polymer additives, are described in detail. The specific applications are organized by technique and a limited amount of detail is given for the various instrumental setups, since these are described elsewhere in other chapters of this volume. 

The methods of analysis of polymer additives and chemicals, such as hydrocarbons, alcohols, etc., are not only restricted to the field of polymer chemistry but can also be applied for the analysis of such materials in the field of food chemistry. In addition, the analysis of polyaromatic hydrocarbons in edible oils has been of extreme importance. Polymeric packaging materials that are intended for food-contact use may contain certain additives that can migrate into the food products which are actually packaged in such products. The amounts of the additives that are permitted to migrate into food samples are controlled by government agencies in order to show... 

Figure 12.1 Analysis of Tinuvin 1577 in 30% virgin olive oil (in hexane), showing (a) the gas cliromatogram comparing the pure oil with a sample at the Tinuvin 1577 detection limit concentration, and (b) the coixesponding liquid chromatogram. Reprinted from Journal of High Resolution Chromatography, 20, A. L. Baner and A. Guggenberger, Analysis of Tinuvin 1577 polymer additive in edible oils using on-line coupled HPLC-GC , pp. 669-673, 1997, with pennission from Wiley-VCH.

A multidimensional system using capillary SEC-GC-MS was used for the rapid identification of various polymer additives, including antioxidants, plasticizers, lubricants, flame retardants, waxes and UV stabilizers (12). This technique could be used for additives having broad functionalities and wide volatility ranges. The determination of the additives in polymers was carried out without performing any extensive manual sample pretreatment. In the first step, microcolumn SEC excludes the polymer matrix from the smaller-molecular-size additives. There is a minimal introduction of the polymer into the capillary GC column. Optimization of the pore sizes of the SEC packings was used to enhance the resolution between the polymer and its additives, and smaller pore sizes could be used to exclude more of the polymer... 

Figure 12.5 Effect of shifting the time window for the ti ansfer. Operation in the SEC-GC analysis of polymer additives in a poly styene matrix, shown foi the following fractions ...

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