Monomers in poly

Since the late 1960 s a few papers have demonstrated compositional analysis of various polymer systans by Raman spectroscopy. For example, Boerio and Yuann (U) developed a method of analysis for copolymers of glycidyl methacrylate with methyl methacrylate and styrene. Sloane and Bramston-Cook (5) analyzed the terpolymer system poly(methyl methacrylate-co-butadiene-co-styrene). The composition of copolymers of styrene-ethylene dimethacrylate and styrene-divinylbenzene was determined by Stokr et (6). Finally, Water (7) demonstrated that Raman spectroscopy could determine the amount of residual monomer in poly(methyl methacrylate) to the % level. This was subsequently lowered to less than 0.1% (8). In spite of its many advantages, the potential of Raman spectroscopy for the analysis of polymer systems has never been fully exploited. 

ASTM, D 3749 - Residual Vinyl Chloride Monomer in Poly(Vinyl Chloride) Resins by Gas Chromatography Headspace Technique (2002)... 

Figure 23-11. Variation of the number-average molar mass of the residue with the percentage amount of eliminated monomer in poly(methyl methacrylates) of different number average initial molar masses (A/n)o. Mn)o values (O) 44,300 ( ) 94,000 (A) 179,000 (A) 650,000 ( ) 725,000 g/mol molecule. (According to N. Grassie and H. W. Melville.)...

Residual vinyl chloride monomer in poly(vinyl chloride) resins ASTM D3749... 

In regard to the solubility of the monomer in its polymer, the diffusion of vinyl chloride into PVC varies with the physical state of the resin. Earlier work frequently dealt with studies involving PVC films more recently, powdered resins were studied. In the latter case, variations in diffusion rates were found to depend on the method of polymerization (emulsion vs, suspension method) as well as on the physicochemical parameters [53]. The equilibrium solubility of vinyl chloride monomer in poly(vinyl chloride) was found to be a function of polymer type, polymer history, time, temperature, and the VCM partial pressure [7]. Above atmospheric pressure, with the ratio of the partial pressure of VCM to the initial partial pressure of the monomer greater than approximately 0.5, the solubility of vinyl chloride is 0.300 gm per gram of poly(vinyl chloride). At lower pressures, the solubility shows a distinct decrease with temperature. Kuchanov and Bort [36] state that the solubility of VCM in PVC varies between 22.1% and 23.7% between 30° and 60°C. 

D3749 Residual Vinyl Chloride Monomer in Poly (Vinyl... 

A polymer is a macromolecule that is constructed by chemically linking together a sequent of molecular fragments. In simple synthetic polymers such as polyethylene or polystyrer all of the molecular fragments comprise the same basic unit (or monomer). Other poly me contain mixtures of monomers. Proteins, for example, are polypeptide chains in which eac unit is one of the twenty amino acids. Cross-linking between different chains gives rise to j-further variations in the constitution and structure of a polymer. All of these features me affect the overall properties of the molecule, sometimes in a dramatic way. Moreover, or... 

The major use of vinylpyrrohdinone is as a monomer in manufacture of poly(vinylpyrrohdinone) (PVP) homopolymer and in various copolymers, where it frequendy imparts hydrophilic properties. When PVP was first produced, its principal use was as a blood plasma substitute and extender, a use no longer sanctioned. These polymers are used in pharmaceutical and cosmetic appHcations, soft contact lenses, and viscosity index improvers. The monomer serves as a component in radiation-cured polymer compositions, serving as a reactive diluent that reduces viscosity and increases cross-linking rates (see... 

Homopolymers of PO and other epoxides are named a number of ways after the monomer, eg, poly(propylene oxide) (PPO) or polymethjioxirane from a stmctural point of view, polyoxypropylene or poly(propylene glycol) or from the Chemicaly hstracts (CA) name, poly[oxy(methyl-l,2-ethanediyl)], a-hydro- CO-hydroxy-. Common names are used extensively in the Hterature and in this article. 

In poly(vinyl acetate) copolymer emulsions, the properties are significantly affected by the composition of the aqueous phase and by the stabilizers and buffers used iu the preparation of these materials, along with the process conditions (eg, monomer concentrations, pH, agitation, and temperature). The emulsions are milk-white Hquids containing ca 55 wt % PVAc, the balance being water and small quantities of wetting agents or protective coUoids. 

The observation in 1949 (4) that isobutyl vinyl ether (IBVE) can be polymerized with stereoregularity ushered in the stereochemical study of polymers, eventually leading to the development of stereoregular polypropylene. In fact, vinyl ethers were key monomers in the early polymer Hterature. Eor example, ethyl vinyl ether (EVE) was first polymerized in the presence of iodine in 1878 and the overall polymerization was systematically studied during the 1920s (5). There has been much academic interest in living cationic polymerization of vinyl ethers and in the unusual compatibiUty of poly(MVE) with polystyrene. 

The auto-acceleration effect appears most marked with polymers that are insoluble in their monomers. In these circumstances the radical end becomes entrapped in the polymer and termination reactions become very difficult. It has been suggested that, in thermodynamic terms, methyl methacrylate is a relatively poor solvent for poly(methyl methacrylate) because it causes radicals to coil while in solution. The termination reaction is then determined by the rate at which the radical ends come to the surface of the coil and hence become available for mutual termination. 

In another study, uniform composite polymethyl-methacrylate/polystyrene (PMMA/PS) composite particles in the size range of 1-10 fim were prepared by the seeded emulsion polymerization of styrene [121]. The PMMA seed particles were initially prepared by the dispersion polymerization of MMA by using AIBN as the initiator. In this polymerization, poly(7V-vinyl pyrolli-done) and methyl tricaprylyl ammonium chloride were used as the stabilizer and the costabilizer, respectively, in the methanol medium. Seed particles were swollen with styrene monomer in a medium comprised of seed particles, styrene, water, poly(7V-vinyl pyrollidone), Polywet KX-3 and aeorosol MA emulsifiers, sodium bicarbonate, hydroquinone inhibitor, and azobis(2-methylbu-... 

The polymerization of vinyl chloride monomer, in common with other vinyl monomers, proceeds by a free-radical mechanism involving the usual steps of initiation, propagation, and termination. Poly(vinyl chloride) is formed in a regular head-to-tail manner Eq. (1) [3-6]. 

In a second novel approach, Mullen and co-workers further developed an inter-molecular repetitive Diels-Aldcr procedure for the generation of dendritic and hy-perbranched poly(phenylcnc)s. Hereby, they applied the concept of reacting A2B-type monomers, in this case monomers containing both cyclopcnladienone (dien-... 

Vinyl Chloride CH2=C HC1 Acrylates, Styrene, W, or oxidizing agents. Forms the Poly-peroxide which decomps exo-thermally at RT Air Vap Monomer. In Air 4.0 to 22.0% or 3.6 to 33.0% > Ambient > Ambient Inhibitor—Phenol (25-100 ppm). Store under press in a cool place. No sparks 22.9 472 Self-polymerizes, catalyzed by oxygen... 

Sfi.F-Test 19.4B Write the formula for (a) the monomer of poly(methyl methacrylate), used in contact lenses (17) (b) two repeating units of polyalanine, the polymer of the amino acid alanine, CH,CH(NH2)COOH. 

Certain commercially important crosslinking reactions are carried out with unsaturated polymers. For example, as will be described later in this chapter, polyesters can be made using bifunctional acids which contain a double bond. The resulting polymers have such double bonds at regular intervals along the backbone. These sites of unsaturation are then crosslinked by reaction with styrene monomer in a free-radical chain (addition) process to give a material consisting of polymer backbones and poly(styrene) copolymer crosslinks. 

The racemic poly(DL-lactide) DL-PLA is less crystalline and lower uelting than the two stereoregular polymers, D-PLA and L-PLA. Further, the copolymers of lactide and glycolide are less crystalline than the two homopolymers of the two monomers. In addition, the lactic acid polymer, because of the methyl group, is more hydrophobic than the glycolide polymer. 

Whereas conventional poly (amino acids) are probably best grouped together with proteins, polysaccharides, and other endogenous polymeric materials, the pseudopoly (amino acids) can no longer be regarded as "natural polymers." Rather, they are synthetic polymers derived from natural metabolites (e.g., a-L-amino acids) as monomers. In this sense, pseudopoly (amino acids) are similar to polylactic acid, which is also a synthetic polymer, derived exclusively from a natural metabolite. 

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