Methyl methacrylate-styrene shell

Figure 14.9 Effect of various impact modifiers (25wt%) on the notched Izod impact strength of recycled PET (as moulded and annealed at 150°C for 16 h) E-GMA, glycidyl-methacrylate-functionalized ethylene copolymer E-EA-GMA, ethylene-ethyl acrylate-glycidyl methacrylate (72/20/8) terpolymer E-EA, ethylene-ethyl acrylate EPR, ethylene propylene rubber MA-GPR, maleic anhydride grafted ethylene propylene rubber MBS, poly(methyl methacrylate)-g-poly(butadiene/styrene) BuA-C/S, poly(butyl acrylate-g-poly(methyl methacrylate) core/shell rubber. Data taken from Akkapeddi etal. [26]...

Sanchez-Silva, L. Rodriguez, J.R Romero, A. Borreguero, A.M. Carmona, M. Sanchez, P. Microencapsulation of PCMs with a styrene-methyl methacrylate copolymer shell by suspension-like... 

Emulsions can be formulated with only hard monomer and plasticized at a later stage, but it is normal to internally plasticize the emulsion by copolymerizing some soft monomer. Vinyl acetate plasticized with an acrylate such as butyl or ethylhexyl acrylate, or a dialkyl maleate, are common combinations. Other hard (high Tg) monomers include methyl methacrylate, styrene, and vinyl chloride. Soft monomers include Vinyl Versatate (Shell Chemicals), ethylene, and vinylidene chloride (Figure 1). 

Preformed particles are incorporated into the epoxy matrix by simple mechanical mixing. The dispersibility of the particles can be improved by 1) introducing crosslinking into the shell or 2) using comonomer-like acrylonitrile or GMA, which increases the interfacial adhesion by polar or chemical interaction [96, 97]. Quan and co-workers [98] reported that for poly (butadiene-co-styrene) core poly (methyl methacrylate) (PMMA) shell particles, the cluster size reduces from 3-5 pm to 1-3 pm as a result of using 5 wt% crosslinker (divinyl benzene). They also found that the cluster size could be further reduced to 1-2 pm by using a methyl methacrylate-acrylonitrile (MMA-AN) or methyl methacrylate-glycidyl methacrylate (MMA-GMA) copolymer shell composition. 

Reference 34, Example 4, Latex shell is methyl methacrylate styrene glycidyl methacrylate, 35 30 30. 

In another recent example, dtrate-capped Au NPs are modified with 1-dodeca-nethiol in a first step. These premade nanoparticles were encapsulated with block copolymers such as poly(styrene-block-acrylic acid) (PS-b-PAA) and poly(methyl-methacrylate-block-acrylic acid) (PMMA-b-PAA) leading to core-shell hybrid materials. The Au NP diameters are 12 and 31 nm with average shell thickness of about 15 nm [121] (Scheme 3.18). 

Core-shell emulsion polymers with a core or rubbery stage based on homopolymers or copolymers of butadiene are used as impact modifiers in matrix polymers, such as ABS, for styrene acrylonitrile copolymer methyl methacrylate (MMA) polymers, poly(vinyl chloride) (PVC), and in various engineering resins such as polycarbonate) (PC) poly(ester)s, or poly(styrene)s, further in thermosetting resins such as epoxies. 

Such impact modifiers containing copolymers of butadiene and styrene and at least one stage or shell of poly(methyl methacrylate) are known MMBS core-shell polymers. 

The vinyl monomers used in this study, methacrylic acid, methyl methacrylate, acrylic acid, methyl acrylate, and acrylonitrile, as well as the solvents, initiators, and polystyrene were supplied by the Aldrich Chemical Company. The styrene-butadiene block copolymer was supplied by Shell as Kraton D1102, known as SBS this contains approximately 75% butadiene and 25% styrene. 

The outer glassy shell is designed to prevent coalescence of rubbery particles during synthesis and drying, and to insure a good interface with the matrix. The shell is usually based on styrene/acrylonitrile or styrene/methyl methacrylate copolymers. Depending on the acrylonitrile or methyl methacrylate content, the compatibility between the shell and the matrix can be varied over a wide range. 

IPN crosslinked PBA, crosslinked uncrosslinked SAN Poly(p-hydroxy styrene), PVPh and EVAl Acrylic core-shell copolymer and either PBT or PET Poly(allyl methacrylate-co-butyl acrylate-co-butanediol dimethacrylate-co-styrene-co-methyl methacrylate) or poly (aery lonitrile-co-butyl aery late-co-tricy clodeceny 1 aery late-co- styrene) Poly(acrylate-V-cyclohexyl maleimide), PMI, and a copolymer PMMA — core, crosslinked butyl acrylate-styrene copolymer — middle layer, and PMMA shell d = 200-300 nm PEG/atactic PMMA blends were characterized by PVT at T = 20-200°C and P = 0-200 MPa. Free volume fraction was calculated from an equation of state... 

S-MMAIPC blend. This blend (Novacor SD-9101) was reported to have better flow, surface finish and scratch resistance than PC/polyester blends and an equivalent level of impact toughness (Table 15.24). It is believed that these formulations also include some acrylic rubber (core-shell type) for impact modification. One would expect a sufficient level of partial miscibility for self-compatibilization between the styrene-methyl methacrylate copolymer (S-MMA) and the polycarbonate especially at high MMA content of the copolymer, since the binary blends of PMMA... 

Zhang JJ, Gao G, Zhang M, et al. (2006) ZnO/PS core-shell hybrid microspheres prepared with miniemulsion polymerization. J Colloid Interface Sci 301 78-84 Mahdavian A, Stirrafi Y, Shabankareh M (2009) Nanocomposite particles with core-shell morphology. 111. Preparation and characterization of nano Al203-poly(styrene-methyl methacrylate) ptirticles via miniemulsion polymerization. Polym Bull 63 329-340... 

Many investigators have studied polymer surfaces for years [74,75] and have been successful in determining combinations of two or more valence states [76,77] by the mathematical process of deconvoluting the peak assignments [78]. It was only recently that latexes were examined by ESCA. Davies et al. [79] prepared a series of homopolymers of poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA), and also poly[(methyl methacrylate)-co-(butyl methacrylate)] (PMMA-PBMA), by surfactant-free emulsion polymerization. It was found that the surface of the latex film was rich in PMMA, which may possibly be explained by the reactivity ratios for the MMA/BMA system (ri = 0.52 and rj = 2.11) [80], Recently, Arora et al. carried out angle-dependent ESCA studies on a series of films prepared from core-shell ionomeric latexes (with a polystyrene core and a styrene/n-butyl acrylate/ methacrylic acid copolymer shell) to determine the distribution of carboxyl groups in the films [81,82]. 

Muller and coworkers prepared disc-like polymer Janus particles from assembled films of the triblock copolymer SBM and, after hydrolysis of the ester groups into methacrylic acid units, used these as Pickering stabilizer in the soap-free emulsion polymerization of styrene and butyl acrylate [111]. Armes and coworkers described the synthesis of PMMA/siUca nanocomposite particles in aqueous alcoholic media using silica nanoparticles as stabilizer [112], extending this method to operate in water with a glycerol-modified silica sol [113, 114]. Sacanna showed that methacryloxypropyltrimethoxysilane [115] in the presence of nanosized silica led to spontaneous emulsification in water, which upon a two-step polymerization procedure afforded armored particles with an outer shell of PMMA [116]. Bon and coworkers demonstrated the preparation of armored hybrid polymer latex particles via emulsion polymerization of methyl methacrylate and ethyl methacrylate stabilized by unmodified silica nanoparticles (Ludox TM O) [117]. Performance of an additional conventional seeded emulsion polymerization step provided a straightforward route to more complex multilayered nanocomposite polymer colloids (see Fig. 14). 

All the commercial PBT/PC and PET/PC blends also contain typically 10-20 wt% of an additional elastomeric impact modifier. The exact nature and the content of the impact modifier is kept proprietary and often forms the basis for a particular blend patent. Typically, core-shell rubbers such as poly(methyl methacrylate)-grafted butadiene-styrene rubber (MBS) or an all acrylic core-shell rubber such as poly (MMA-g-n-BuA) are used (Nakamura et al. 1975 Chung et al. 1985). ABS (with high polybutadiene content >50 %) or ASA rubber (>50 % aciylate rubber) have also been used. The presence of such a rubber component is definitely needed to obtain high notched Izod impact strengths (>500 J/m) in these blends. 

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