Polymethyl acetal

Examples of thermoplastics are polyethylene, polyvinyl chloride, polystyrene, nylon, cellulose acetate, acetal, polycarbonate, polymethyl methacrylate and polypropylene. 

Cellulose Esters Epoxy Resins Lignins Polystyrene Poly (2-vinyl pyridine) Polyvinyl Chloride Polymethyl methacrylate Polyphenylene Oxide Phenolics Polycarbonate Polyvinyl Acetate, etc. Polyvinyl butyral SBR rubber, etc., etc. 

This molecule is a copolymer with polymethyl methacrylate (PMMA) in acrylic latex paints, where the hydrophobic PMMA is surrounded by hydrophilic polyvinyl acetate molecules. Such a suspension of a hydrophobic polymer wrapped in a hydrophilic polymer is called a latex. 

Various polymeric materials were tested statically with both gaseous and liquefied mixtures of fluorine and oxygen containing from 50 to 100% of the former. The materials which burned or reacted violently were phenol-formaldehyde resins (Bakelite) polyacrylonitrile-butadiene (Buna N) polyamides (Nylon) polychloroprene (Neoprene) polyethylene polytriflu-oropropylmethylsiloxane (LS63) polyvinyl chloride-vinyl acetate (Tygan) polyvinylidene fluoride-hexafluoropropylene (Viton) polyurethane foam. Under dynamic conditions of flow and pressure, the more resistant materials which binned were chlorinated polyethylenes, polymethyl methacrylate (Perspex) polytetraflu-oroethylene (Teflon). 

Cobalt bromide is used as a catalyst in the technology of production of arylcarboxylic acids by the oxidation of methylaromatic hydrocarbons (toluene, p-xylene, o-xylene, polymethyl-benzenes). A cobalt bromide catalyst is a mixture of cobaltous and bromide salts in the presence of which hydrocarbons are oxidized with dioxygen. Acetic acid or a mixture of carboxylic acids serves as the solvent. The catalyst was discovered as early as in the 1950s, and the mechanism of catalysis was studied by many researchers [195-214],... 

For example, Melville [26] studied the ultrasonically induced polymerisation of monomers such as styrene, methyl methacrylate and vinyl acetate in the presence and absence of polymethyl methacrylate and found that the polymerisation rates ( 1 % conversion/h) were not substantially increased by the presence of polymer. He concluded, in contrast to Driscoll, that the degradation of polymer was not the major source of radical production. Using hydroquinone as an inhibitor, he was able to deduce, from retardation times, that the rate of radical production was 2 X 10 mol dm s. A typical value for radical production using as an example the thermal initiation of AZBN (10 mol dm ) at 60 °C is 2 x 10" mol dm s" ... 

The selective dense layer of hydrophilic membranes is made from different polymers with a high affinity for water. These polymers contain ions, oxygen functions like hydroxyl, ester, ether or carboxylic moieties, or nitrogen as imino or imi-do groups. Preferred hydropilic polymers are polyvinylalcohol (PVA) [32], poly-imides, cellulose acetate (CA) or natural polymers like chitosan [33] or alginates. Organophilic membranes usually consist of crosslinked silicones, mostly polydimethyl siloxane (PDMS) or polymethyl octyl siloxane (POMS). 

The polyvinyl acetate samples (Aldrich 18250-8 Lot 1 and Lot 3) and a polymethyl methacrylate sample (Aldrich 18226-5) were obtained from the Aldrich Chemical Co., Milwaukee, WI. 

Fig. 23. Polymerization of monomers in masticating polystyrene and polymethyl methacrylate. Curves 1-6 1 ml methacrylic acid, styrene, methyl methacrylate, ethyl acrylate, acrylonitrile, and vinyl acetate, respectively, in 3 g polystyrene. Curves 7-12 2 ml methacrylic acid, methyl methacrylate, acrylonitrile, ethyl acrylate, styrene, and vinyl acetate, respectively, in 3g polymethyl methacrylate. The limiting viscosity numbers for points along Curves 2 and 3...

Fig. 14. Molecular-weight dependences of Rf observed for polymethyl methacrylate samples, coded PMA-3 and PMA-2 (left and right spot in each chromatogram, respectively), using three different but equi-ehiotropic binaries, (a) benzene + acetone, (b) isopropyl acetate + methyl formate and, (c) ethyl acetate + methyl acetate...

Onogi,S., Masuda,T., Ibaragi,T. Rheological properties of polymethyl methacrylate and polyvinyl acetate in the molten state. Kolloid-Z. Z. Polymere 222, 110-124... 

Eq. (5) in conjunction with Eqs. (8) and (9) have, so far, provided adequate representation of experimental isotherms6 32, which are characterized by an initial con vex-upward portion but tend to become linear at high pressures. Values of K, K2 and s0 have been deduced by appropriate curve-fitting procedures for a wide variety of polymer-gas systems. Among the polymers involved in recent studies of this kind, one may cite polyethylene terephthalate (PET) l2 I4), polycarbonate (PC) 19 22,27), a polyimide l6,17), polymethyl and polyethyl methacrylates (PMMA and PEMA)l8), polyacrylonitrile (PAN)15), a copolyester 26), a polysulphone 23), polyphenylene oxide (PPO)25), polystyrene (PS) 27 28), polyvinyl acetate 29) and chloride 32) (PVAc and PVC), ethyl cellulose 24) (EC) and cellulose acetate (CA) 30,3I>. A considerable number of gases have been used as penetrants, notably He, Ar, N2, C02, S02 and light hydrocarbons. 

In contrast the polymerization of vinyl acetate in the presence of polymethyl methacrylate gives after selective precipitation appreciable amounts of pure graft copolymer, independently of the nature of the initiator moreover the degree of grafting, evaluated by infrared spectrometry, is about equally important. Similar results were obtained in the system vinyl acetate-polyethyl a-chloroacryl ate. 

In Table 3 results axe summarized which were obtained at three different temperatures for a solution of 2.5 g polymethyl methacrylate in 10 g vinyl acetate containing 50 mg benzoyl peroxide (203). 

Table 3. Grafting of vinyl acetate on polymethyl methacrylate...

By ultrasonic irradiation of a solution of polymethyl methacrylate in vinyl acetate or in styrene, no appreciable amount of block copolymer could be found 154). Henglein succeeded with addition of acrylonitrile to polyacrylamide dissolved in water 100). Although acrylonitrile itself... 

The mechanical degradation and production of macroradicals can also be performed by mastication of polymers brought into a rubbery state by admixture with monomer several monomer-polymer systems were examined (10, 11). This technique was for instance studied for the cold mastication of natural rubber or butadiene copolymers in the presence of a vinyl monomer (13, 31, 52). The polymerization of methyl methacrylate or styrene during the mastication of natural rubber has yielded copolymers which remain soluble up to complete polymerization vinyl acetate, which could not produce graft copolymers by the chain transfer technique, failed also in this mastication procedure. Block and graft copolymers were also prepared by cross-addition of the macroradicals generated by the cold milling and mastication of mixtures of various elastomers and polymers, such as natural rubber/polymethyl methacrylate (74), natural rubber/butadiene-styrene rubbers (76) and even phenol-formaldehyde resin/nitrile rubber (125). 

For example polymethyl acrylate was treated with phosphorus penta-chloride to form copolymers containing 26.6 and 37.8% acid chloride units these copolymers, by treatment with tert-butyl hydroperoxide, yield 4.9 to 6% perester containing polymers which were used for grafting styrene, vinyl acetate, acrylonitrile (177). 

In the case of styrene the polymer contains at both ends a carboxyl group (chain termination by coupling), while polymers characterized by a termination reaction by disproportionation (polyvinyl acetate, polymethyl methacrylate) contain only one carboxyl end group. The carboxyl groups in these polymers were transformed to acid chlorides and coupled with a diol, e.g. 1,6-hexanediol. The comparison of the molecular weight of the polymers before and after condensation permits to elucidate the... 

In order to demonstrate the application of these equations, examples of the determination of chain transfer constants are given for three cases (1) polystyrene, in which the mutual destruction of polymer radicals is by combination, (2) polymethyl methacrylate, in which combination as well as disproportionation is important, and (3) polyvinyl acetate, in which chain transfer predominates. 

PC PE PES PET PF PFA PI PMMA PP PPO PS PSO PTFE PTMT PU PVA PVAC PVC PVDC PVDF PVF TFE SAN SI TP TPX UF UHMWPE UPVC Polycarbonate Polyethylene Polyether sulfone Polyethylene terephthalate Phenol-formaldehyde Polyfluoro alkoxy Polyimide Polymethyl methacrylate Polypropylene Polyphenylene oxide Polystyrene Polysulfone Polytetrafluoroethylene Polytetramethylene terephthalate (thermoplastic polyester) Polyurethane Polyvinyl alcohol Polyvinyl acetate Polyvinyl chloride Polyvinyl idene chloride Polyvinylidene fluoride Polyvinyl fluoride Polytelrafluoroethylene Styrene-acrylonitrile Silicone Thermoplastic Elastomers Polymethylpentene Urea formaldehyde Ultrahigh-molecular-weight polyethylene Unplasticized polyvinyl chloride... 

Polymethyl(phenyl)silsesquioxane production comprises the following stages the drying of potassium acetate in toluene the preparation of the mixture of methyl- and phenyltrichlorosilanes and its acetylation alcoholysis the flushing and filtration of silanol mixture the distillation of toluene and condensation of alcoholysis products the preparation of varnish, its settling and centrifuging. 

Polychlorobutene Polymethyl-metacrylate Styrene-butadiene copolymer Vinyl acetate-acrylic copolymer... 

Fig. 3. Plots of D against penetrant concentration for the system polymethyl acrylate — ethyl acetate at different temperatures [Fujita, Kishimoto and Matsumoto (I960)]...

---