Polyacrylates, additives

VI additives to improve the viscosity index polymethacrylates, polyacrylates, olefin polymers. 

The most widely used pitch control method is the addition of pitch dispersants, which can be either organic, ie, typically anionic polymers such as naphthalene sulfonates, ligninsulfonates, and polyacrylates (33,34), or inorganic, ie, typically clay or talc. The polymers maintain the pitch as a fine dispersion in the pulp, preventing agglomeration and potential deposition on the paper machine or the sheet. When talc, clay, or other adsorbent fillers are added to the furnish, moderate amounts of pitch can adsorb on these materials, producing a nontacky soHd that can be retained in the sheet. 

Other. A large variety of additives are used in paper-coatiag colors primarily to modify the physical properties of the colors (102). At high soHds concentrations in water, mineral pigment particles tend to associate and form viscous pastes. Dispersants (qv) are used to prevent this and to provide low viscosity slurries. Common dispersants include polyphosphates and sodium polyacrylate [9003-04-7]. Various water-soluble polymers are added to coatiag colors and act as water-retention agents and as rheology modifiers. 

Several factors were utilized in bringing formaldehyde release down. In particular, resin manufacturer executed more careful control of variables such as pH, formaldehyde content, and control of methylolation. There has also been a progressive decrease in the resin content of pad baths. The common practice of applying the same level of resin to a 50% cotton—50% polyester fabric as to a 100% cotton fabric was demonstrated to be unnecessary and counter productive (89). Smooth-dry performance can be enhanced by using additives such as polyacrylates, polyurethanes, or siUcones without affecting formaldehyde release. 

Standard-grade PSAs are usually made from styrene-butadiene rubber (SBR), natural rubber, or blends thereof in solution. In addition to rubbers, polyacrylates, polymethylacrylates, polyfvinyl ethers), polychloroprene, and polyisobutenes are often components of the system ([198], pp. 25-39). These are often modified with phenolic resins, or resins based on rosin esters, coumarones, or hydrocarbons. Phenolic resins improve temperature resistance, solvent resistance, and cohesive strength of PSA ([196], pp. 276-278). Antioxidants and tackifiers are also essential components. Sometimes the tackifier will be a lower molecular weight component of the high polymer system. The phenolic resins may be standard resoles, alkyl phenolics, or terpene-phenolic systems ([198], pp. 25-39 and 80-81). Pressure-sensitive dispersions are normally comprised of special acrylic ester copolymers with resin modifiers. The high polymer base used determines adhesive and cohesive properties of the PSA. 

Ionic repulsion between anionic samples and the resin causes poor resolution. As shown in Fig. 4.17, the addition of only 0.01 M NaNO, results in normal elution and peak shape for an anionic polymer, sodium polyacrylate. 

Variation of melt viscosity for both the preblends and preheated blends with the blend ratio are shown in Fig. 19. There are two distinct regions in viscosity change with the addition of polyacrylic rubber (ACM) in the blends. First, in the higher shear rate region, the viscosity increases with the addition of the ACM (up to 40% ACM) in the blend and then it decreases. In the lower... 

Major fiber-making polymers are those of polyesters, polyamides (nylons), polyacrylics, and polyolefins. Polyesters and polyamides are produced by step polymerization reactions, while polyacrylics and polyolefins are synthesized by chain-addition polymerization. 

In addition to carbonates and/or phosphates, a variety of substances have also been used to act as sludge conditioners —e.g. starches, lignins, polyacrylates etc. Other substances, such as nitrites and sulphates are claimed to have some value in the suppression of caustic cracking (see Section 5.1). 

The most widely known of these tracer polymers are the Trasar products from Nalco, of which the latest offering is NexGuard , a polyacrylic sulfonate (PAS) designed for high-pressure operation. Other tracer polymer systems include Optidose (from Rohm and Haas Company) and Bel-Trak (Biolab/Water Additives Division of Great Lakes Chemical Corp.). 

Certain oxides of divalent metals, those of ZnO, CuO, SnO, HgO, and PbO, form cements that are hydrolytically stable in addition MgO, CaO, BaO and SrO form cements that are softened when exposed to water. Compressive strengths of these materials range from 26 to 83 MPa, the strongest being the copper(II) and zinc polyacrylate cements (Table 5.1). Crisp, Prosser Wilson (1976) found that for divalent oxides the rate of reaction increased in the order... 

Brandt [200] has extracted tri(nonylphenyl) phosphite (TNPP) from a styrene-butadiene polymer using iso-octane. Brown [211] has reported US extraction of acrylic acid monomer from polyacrylates. Ultrasonication was also shown to be a fast and efficient extraction method for organophosphate ester flame retardants and plasticisers [212]. Greenpeace [213] has recently reported the concentration of phthalate esters in 72 toys (mostly made in China) using shaking and sonication extraction methods. Extraction and analytical procedures were carefully quality controlled. QC procedures and acceptance criteria were based on USEPA method 606 for the analysis of phthalates in water samples [214]. Extraction efficiency was tested by spiking blank matrix and by standard addition to phthalate-containing samples. For removal of fatty acids from the surface of EVA pellets a lmin ultrasonic bath treatment in isopropanol is sufficient [215]. It has been noticed that the experimental ultrasonic extraction conditions are often ill defined and do not allow independent verification. 

Various additives show considerable extraction resistance, such as impact modifiers (polyacrylates and polyblends PVC/EVA, PVC/ABS, etc.), highpolymeric processing aids (PMMA-based), elastomers as high-MW plasticisers, reactive flame retardants (e.g. tetrabromobisphenol-A, tetrabromophthalic anhydride, tetrabromophthalate diol, dibromostyrene). Direct measurement of additives by UV and IR spectroscopy of moulded films is particularly useful in analysing for additives that are difficult to extract, although in such cases the calibration of standards may present a problem and interferences from other additives are possible. 

Table I demonstrates that most liquid crystalline polymers lacking a spacer are formed from a flexible polyacrylate backbone. In contrast, the methyl substituent in polymethacrylate backbones both reduce main chain mobility and imposes additional steric barriers to mesophase formation. Therefore, successful liquid crystalline formation of polymethacrylates has been achieved only...

The proposed mechanism of effect of surfactant and ultrasound is reported in Fig. 7.5. The long chain surfactant molecules attach to surface of nanoparticles due to physical adsorption. Only thin layer is adsorbed onto the CaC03 nanoparticles. Due to presence of ultrasound and use of surfactant will control the nucleation. Surfactant keeps the particles away from each other by preventing flocculation due to change in surface tension of reaction mass. The concentration of additives was changed from 0.2 to 1.0 g/L. Addition of 0.2 g/L tripolyphosphate shows the increase in the rate of precipitation which is determined from the Ca(OH)2 consumption. Polyacrylic acid shows the least rate of precipitation (0.115 mol/1), which... 

A wide range of additives can also be introduced into the sol-gel matrices in order to modulate the hydrophobicity of the materials and to improve enzyme stability, activity and accessibility, leading to hybrid or even composite sol-gel matrices. Polymers [157,179,180] such as polyethyleneglycol, polyvinylpyrrolidone, polyvinylalcohol, polyglycidol, polyethyleneimine, polyacrylate have been simultaneously entrapped with enzymes in a siloxane matrix, as well as organic additives (sugar, amino add)... 

A newer addition is in-tube SPME that makes use of an open capillary device and can be coupled online with GC, HPLC, or LC/MS. All these techniques and their utilization in pharmaceutical and biomedical analysis were recently reviewed by Kataoka.45 Available liquid stationary fiber coatings for SPME include polydimethylsiloxane (PDMS) and polyacrylate (PA) for extracting nonpolar and polar compounds, respectively. Also in use for semipolar compounds are the co-polymeric PDMS-DVB, Carboxen (CB)-PDMS, Carbowax (CW)-DVB, and Carbowax-templated resin (CW-TPR). A few examples of in-tube SPME extractions from biological matrices are shown in Table 1.19 and drawn from Li and coworkers.166... 

During the next four years many additional new polymers were synthesized. Most proved of little commercial value, but the list includes three of the top-ranked popular plastic families - the polyvinyls used for phonograph records and floor tiles polyacrylics (such as Lucite) used in paints, airplane windows and buna N and buna S, two versions of synthetic rubber. Thus few households are not affected by even his early contributions. 

In this investigation, you will examine three different polymers. First, you will examine the addition polymer sodium polyacrylate. This polymer contains sodium ions trapped inside the three-dimensional structure of the polymer. When placed in distilled water, the concentration of sodium ions inside the polymer is much greater than the concentration of sodium ions outside the polymer. The concentration imbalance causes water molecules to move hy diffusion into the polymer. As a result, the polymer absorbs many times its own mass in distilled water. 

The ultrasonic degradation of aqueous polyacrylic acid decreases with the addition of ether i. e. increased vapour pressure (see Section 2.6.2). 

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