Polymethylmethacrylate

Plasticizers are used in polymethylmethacrylate in very specific cases only. PMMA ionomers are the most likely nsers of the ionic plasticizers. 

Atactic (amorphous) polypropylene is a popnlar plasticizer in many applications, such as modified bitumen roofing, paper lamination, adhesives and sealants, asphalt pavement modification, wire and cable, carpet, tiles, films, and antomotive products. In some applications, plasticizers are nsed in polypropylene processing  

Poly(N-vinyl carbazole), PVK, is a glassy polymer which easily fails by a cracking fracture. Plasticizers are needed to improve mechanical properties, reduce viscosity, and lower processing temperatnre. PVK is employed in photorefractive systems and as such it must possess photoconductivity and electro-optic effects. These ate related to the crystallization and the glass transition temperature.  

Numerous photoconductive plasticizers are used to lower the glass transition temperature to below 20°C and act as hole transporting plasticizers. These include N-meth-ylcaibazole, N-ethylcaibazole, N-butylcarbazole, N-hexylcaibazole, N-phenylcarbazole, 

3-biscarbazolylpropane, o-nitroanisole, m-nitroanisole, p-nitroanisole, and tripheny-lamine.  

The degradation behaviour of polymethylmethacrylate is easily characterized by thermal volatilization analysis [87] (Fig. 29). Monomer is obtained in very high yield in all cases. A polymer sample prepared by a free radical reaction undergoes a rapid depolymerization at about 275°C as indicated by the first peak. The second peak, situated between 350 and 400°C, corresponds to a second mode of initiation of chain depolymerization. For samples prepared by anionic polymerization, the first peak is not observed. Depolymerization of the whole sample occurs above 350°C. 

The thermal degradation of polymethylmethacrylate was investigated many years ago by isothermal methods [88, 89]. The two mechanisms of chain depolymerization were already identified at that time and analysed. At temperatures below 270°C, the reaction is initiated at the double bonds situated at chain ends and formed by radical disproportionation 

If the molecular weight of the polymer residue is plotted as a function of the percentage degradation to monomer (Fig. 30) it is found to be 

In the case of chain end initiation the number of possible initiation sites per unit weight is inversely proportional to x and, if the zip length I/7 is larger than x, the amount of monomer formed per break is proportional to x. The over-all rate must thus be independent of x, and 

Above 270° C, end initiation and random initiation occur simultaneously. If the temperature is raised above 300° C, the molecules with labile chain ends are rapidly removed and the random-initiated degradation process can be studied independently [90]. In this case also the kinetic relationship deduced from weight loss experiments depends on the relative values of the degree of polymerization x and the zip length 1/7. It has been shown by Cameron and Kerr [90] that when the zip length is less 

Between 1989 and 1997, Ohtani and co-workers [38, 54-60] published a series of papers on the application of Py-GC to the determination of end-groups in polymethylmethacrylate (PMMA). 

In earlier work Ohtani and co-workers [54] identified end-groups in PMMA by high resolution Py-GC. 

Minor peaks in the chromatogram were associated with end-groups derived from benzoyl peroxide polymerisation initiator or dodecane thiol chain transfer agent reactions. End-group data were related to molecular weight data. 

Ohtani and co-workers [58] used Py-GC at 700 °C to determine the end-groups in PMMA macromonomers and their prepolymers which had been synthesised radically in the presence of azobis(isobutyronitrile) (AIBN) as initiator and mercaptoacetic acid (MCAA) or mercaptopropionic acid (MPA) as chain transfer reagent. 

Because one of the end groups in most of the PMMA examined in this study should have either a sulfur atom or a cyano group, the Py-GC system is equipped with a simultaneous multidetection system. A flame ionisation detector (FID), was always used in conjunction with either a sulfur-selective flame photometric detector (FPD) or a nitrogen-phosphorus detector (NPD). 

This is a very clear plastic with good light exposure properties. Chemically it is resistant to water, alkalies, many dilute acids and aqueous salt solutions. This polymer is too expensive for packaging. It does however have one application as a food quality plastic, namely the fabrication of artificial dentures. 

Major polymer applications optical fibers, dials, optical components, household items, car rear lights, artificial stones (filled products) for injection molded bath sinks, and kitchen worktops, bone cement, composites, medical applications (e.g. bone cement) 

Important processing methods casting, injection molding, compression molding 

Typical fillers aluminum hydroxide, silica, titanium dioxide, glass fiber, mica, barium sulfate, titanium fiber, nickel, aluminum 

Typical concentration range generally - 20-30 wt% carbon black - 5-30 wt% glass powder in bone cement - 30-80 wt% titanium fiber - 1.5%, aluminum or nickel for conductive applications - 20 vol% 

Special methods of incorporation fillers are most frequently dispersed in monomer in the presence of catalyst and monomer is then polymerized 

Cho and co-workers [16] used reverse phase high pressure liquid chromatography to prepare fractions for SEC analysis of stereoregular PMMA) and examined these fractions by MALDI-ToF mass spectroscopy to determine molecular weights and MWD of the fractions. 

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Perspex Trade name for cast polymethylmethacrylate sheet - an acrylic resin. 

The way in which these factors operate to produce Type III isotherms is best appreciated by reference to actual examples. Perhaps the most straightforward case is given by organic high polymers (e.g. polytetra-fluoroethylene, polyethylene, polymethylmethacrylate or polyacrylonitrile) which give rise to well defined Type III isotherms with water or with alkanes, in consequence of the weak dispersion interactions (Fig. S.2). In some cases the isotherms have been measured at several temperatures so that (f could be calculated in Fig. 5.2(c) the value is initially somewhat below the molar enthalpy of condensation and rises to qi as adsorption proceeds. In Fig. 5.2(d) the higher initial values of q" are ascribed to surface heterogeneity. 

Fig. 5.2 Type III isotherms, (a) n-hexane on PTFE at 25°C (b) n-octane on PTFE at 20 C (c) water on polymethylmethacrylate at 20°C (d) water on bis(A-polycarbonate) (Lexan) at 20°C. The insets in (c) and (d) give the curves of heat of adsorption against fractional coverage the horizontal line marks the molar heat of liquefaction. (Redrawn from diagrams in the original papers, with omission of experimental points.)...

Fig. 8. Election micrograph of a polymethylmethacrylate foamed by rapid pressure release with carbon dioxide at 40°C and 34.47 MPa (4998 psi) (39).

Golovin, M.N., Technical Literature on the Decomposition of Polymethylmethacrylate (PM MSA), Part I, Battelle-Columbus Laboratories Report No. R-6059, Columbus, OH, October 1980. 

Polymethylmethacrylate (Acrylic and PMMA) Nylon, alias Polyamide (PA)... 

Many of the most floppy polymers have half-melted in this way at room temperature. The temperature at which this happens is called the glass temperature, Tq, for the polymer. Some polymers, which have no cross-links, melt completely at temperatures above T, becoming viscous liquids. Others, containing cross-links, become leathery (like PVC) or rubbery (as polystyrene butadiene does). Some typical values for Tg are polymethylmethacrylate (PMMA, or perspex), 100°C polystyrene (PS), 90°C polyethylene (low-density form), -20°C natural rubber, -40°C. To summarise, above Tc. the polymer is leathery, rubbery or molten below, it is a true solid with a modulus of at least 2GNm . This behaviour is shown in Fig. 6.2 which also shows how the stiffness of polymers increases as the covalent cross-link density increases, towards the value for diamond (which is simply a polymer with 100% of its bonds cross-linked. Fig. 4.7). Stiff polymers, then, are possible the stiffest now available have moduli comparable with that of aluminium. 

The next simplest group of linear polymers is the vinylidcnc group. Now two of the hydrogens of ethylene are replaced by radicals. Polymethylmethacrylate (alias PMMA,... 

Where transparency is required, a range of polymers is available. Polystyrene is the least expensive but polymethylmethacrylate has an outstanding high light transmission combined with excellent weathering properties. Also to be considered are the polycarbonates, glass-clear polyamides, SAN, butadiene-styrene block copolymers, MBS polymers, plasticised PVC, ionomers and cellulose esters such as cellulose acetate. 

Fig. 2 shows one application of ATR depth profiling. In this case, ATR spectra were obtained as a function of angle of incidence from a polymethylmethacrylate (PMMA) film of thickness 0.5 p.m that was deposited onto a germanium hemi-cylinder [4]. The solid line represents the ATR spectrum of PMMA while the squares represent the film thickness that was recovered from the infrared spectra using four different bands. It can be observed that the recovered film thickness was very close to the measured thickness. 

Leadley and Watts used monochromaticized A1K radiation to investigate the interactions that were responsible for adhesion between polymers and substrates [24]. When polymethylmethacrylate (PMMA) was adsorbed onto silicon substrates, the C(ls) spectrum shown in Fig. 21a was obtained. Originally, it was... 

Friedrich et al. also used XPS to investigate the mechanisms responsible for adhesion between evaporated metal films and polymer substrates [28]. They suggested that the products formed at the metal/polymer interface were determined by redox reactions occurring between the metal and polymer. In particular, it was shown that carbonyl groups in polymers could react with chromium. Thus, a layer of chromium that was 0.4 nm in thickness decreased the carbonyl content on the surface of polyethylene terephthalate (PET) or polymethylmethacrylate (PMMA) by about 8% but decreased the carbonyl content on the surface of polycarbonate (PC) by 77%. The C(ls) and 0(ls) spectra of PC before and after evaporation of chromium onto the surface are shown in Fig. 22. Before evaporation of chromium, the C(ls) spectra consisted of two components near 284.6 eV that were assigned to carbon atoms in the benzene rings and in the methyl groups. Two additional... 

Common examples of the high Tg macromers are based on polystyrene or polymethylmethacrylate (PMMA) polymers of sufficiently high molecular weight to have a high T (typically on the order of 70-100°C as measured by differential scanning calorimetry) and also to make them immiscible with the acrylic polymer backbone once the solvent or heat has been removed. Typical molecular weight of the polystyrene or PMMA macromers is on the order of 5000-10,000 Da. Their generic structure can be pictured as in Fig. 13 (shown there for polystyrene). 

Vinyl chloride (1835) formed by reacting acetylene with hydrochloric acid, was polymerized a.v polyvinyl chloride (PVC) in 1912, The theory of polymerization by Staudinger in the 1920s- led to the advances that followed. The acrylate were polymerized as polymethylmethacrylate to come into production in 1927. Polystyrene was developed. similarly and concurrently. Polyethylene came into production in 1939 for use in radar and now is ubiquitous. 

Polymethylmethacrylate is used with HFIP. Figure in parenthese is estimated value. 

Let us consider the separation of polymethylmethacrylate (PMMA) on a nonmodified silica column as an example. In THE (medium polar eluent) the PMMA eludes in size exclusion mode because the dipoles of the methylmethacrylate (MMA) are masked by the dipoles of the THE. Using the nonpolar toluene as the eluent on the same column, the separation is governed by adsorption because the dipoles of the carbonyl group in the PMMA will interact with the dipoles on the surface of the stationary phase. The separation of PMMA in the critical mode of adsorption can be achieved by selecting an appropriate THF/toluene mixture as the eluent. In this case all PMMA samples... 

Smaller diameter columns are especially useful when expensive solvents are used. Figure 11.3 shows the analysis of poly (1,4-butylene terephthalate) using a Waters Alliance narrow-bore GPC system, quantitated against narrow polymethylmethacrylate standards. In this case, the solvent used is hexaflu-oro-2-isopropanol with 0.05 M sodium trifluoroacetic acid at a flow rate of... 

Uniform polymeric microspheres of micron size have been prepared by dispersion polymerization. This process is usually utilized for the production of uniform polystyrene and polymethylmethacrylate microspheres in the size range of 0-1-10.0 /Am. 

ACPA azobis(4-cyanopentanoic acid) AIBN azobis isobutyronitrile) BPO benzoyl peroxide DVB divinyl benzene, EGA 2-ethylcyano-acrylate HPC hydroxypropyl cellulose MMA methyl methacrylate PAAc polyacrylic acid PEI polyethyleneimine, PEO/PPO polyethylene oxide/polypyropylene oxide copolymer PVME polyvinylmethylether PVP polyvinylpyrrolidone K-30 DMSO dimethylsulfoxide PGA polyglutaraldehyde CMS chloromethylstyrene PMMA-g-OSA polymethylmethacrylate grafted oligostearic acid. 

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Since 2-hydroxy-4-alkoxybenzophenones are widely used to stabilize polystyrene, flexible and rigid PVC, celluloses, acrylics, and polyolefins such as PE and PP, the polymeric UV stabilizers shown in Table 1 are used with polystyrene, polymethylmethacrylate, and cellulose triacetate (CTA). The polymeric-HALS are used in polyolefins. 

Interpenetrating network polymer. In a separate study, it was shown that cardanol-formaldehyde resins foiTn semi-interpenetrating networks with polymethylmethacrylate (PMMA). Although interpenetration of CF... 

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