Poly impact-modified

Poly(methyl methacrylate) Cast sheet Impact- modified Heat- resistant ... 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

MBS polymers are prepared by grafting methyl methacrylate and styrene onto a styrene—butadiene mbber in an emulsion process. The product is a two-phase polymer useful as an impact modifier for rigid poly(vinyl chloride). 

Poly(vinyl chloride). PVC is one of the most important and versatile commodity polymers (Table 4). It is inherently flame retardant and chemically resistant and has found numerous and varied appHcations, principally because of its low price and capacity for being modified. Without modification, processibiUty, heat stabiUty, impact strength, and appearance all are poor. Thermal stabilizers, lubricants, plasticizers, impact modifiers, and other additives transform PVC into a very versatile polymer (257,258). 

Also, PBT is blended with poly(ethylene terephthalate) (PET), polysulfone, and SMA (303). PET may also be blended with a number of other engineering polymers, such as PC and impact modifiers. 

Not only ate ABS polymers useful engineering plastics, but some of the high mbber compositions are excellent impact modifiers for poly(vinyl chloride) (PVC). Styrene—acrylonitrile-grafted butadiene mbbers have been used as modifiers for PVC since 1957 (87). 

The largest volume commercial derivatives of 1-butanol are -butyl acrylate [141-32-2] and methacrylate [97-88-1] (10). These are used principally ia emulsion polymers for latex paints, ia textile appHcations and ia impact modifiers for rigid poly(vinyl chloride). The consumption of / -butanol ia the United States for acrylate and methacrylate esters is expected to rise to 182,000—186,000 t by 1993 (10). 

At one time butadiene-acrylonitrile copolymers (nitrile rubbers) were the most important impact modifiers. Today they have been largely replaced by acrylonitrile-butadiene-styrene (ABS) graft terpolymers, methacrylate-buta-diene-styrene (MBS) terpolymers, chlorinated polyethylene, EVA-PVC graft polymers and some poly acrylates. 

Blending of ABS with an acrylic material such as poly(methyl methacrylate) can in some cases allow a matching of the refractive indices of the rubbery and glassy phases and providing that there is a low level of contaminating material such as soap and an absence of insoluble additives a reasonable transparent ABS-type polymer may be obtained. More sophisticated are the complex terpolymers and blends of the MBS type considered below. Seldom used on their own, they are primarily of use as impact modifiers for unplasticised PVC. 

In a partially crystalline homopolymer, nylon 6, property enhancement has been achieved by blending with a poly(ethylene-co-acrylic acid) or its salt form ionomer [24]. Both additives proved to be effective impact modifiers for nylon 6. For the blends of the acid copolymer with nylon 6, maximum impact performance was obtained by addition of about 10 wt% of the modifier and the impact strength was further enhanced by increasing the acrylic acid content from 3.5 to 6%. However, blends prepared using the salt form ionomer (Sur-lyn 9950-Zn salt) instead of the acid, led to the highest impact strength, with the least reduction in tensile... 

Crystalline polymers, e.g., nylon, poly(butylene terphthalate), are not easily impact-modified. The crystalline domains can act as crack initiation sites. Amorphous polymers with high Tgs are more amenable to modification, e.g., PS, PVC, PC, although PC is tough because of H-bonding that occurs between the polymer chains. 

Properties Poly(methyl methacrylate) Cast sheet Impact- modified Heat- resistant Alkyd, molded Acrylic poly(vinyl chloride) alloy styrene-poly(vinyl chloride) alloy... 

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]...

MBS (methyl methacrylate-butadiene-styrene) graft copolymers are known as one of the most efficient non-reactive impact modifiers for PET and also poly(vinyl chloride) (PVC). MBS is used commercially as an effective impact modifier for PET recyclate [27], Typical MBS rubber particles contain an elastomeric core of... 

Methyl methacrylate is polymerized to poly(methyl methacrylate), which is used in cast and extruded sheet (32%), surface coatings (24%), molding powder and resins (15%), impact modifiers (13%), and emulsion polymers... 

Actually, ABS can be considered as an impact modifier for PC. PC/ABS blends have been compatibilized with both maleic anhydride (MA)-grafted poly(propylene) (PP) and a solid epoxy resin of the bisphenol A type. Both compatibilizers are effective for formulations of an ABS content up to 30%. The the impact strength of the compatibilized blends was close to that of PC. However, above 40% ABS content, the impact strength decreases significantly (19). 

Such materials essentially contain PS as the matrix polymer and uniformly dispersed in this matrix are elastomeric types of particles, which form the soft phase (3). The soft phase is essentially composed of poly(butadiene) or of block copolymers of butadiene and styrene. This soft phase can be also addressed as the impact modifier for PS. 

Basically, HIPS is an impact modified PS. We do not treat this impact modifier as a special additive, since it is not a special additive, but an essential additive. However, sometimes HIPS itself is used as an impact modifier in certain compositions, e.g. of poly(arylene ether)s (24). 

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. 

Core-shell polymers were commercially introduced as impact modifiers for poly(vinyl chloride) PVC, in the 1960s. They are produced by a two-stage latex emulsion polymerization technique (Cruz-Ramos, 2000). The core is a graftable elastomeric material, usually crosslinked, that is insoluble in the thermoset precursors. Typical elastomers used for these purposes are crosslinked poly(butadiene), random copolymers of styrene and butadiene,... 

DMTA is a very interesting tool for characterizing heterogeneous materials in which domains of distinct Tg values coexist. The most interesting cases involve modified thermosets of different types (see Chapter 8). Examples are the use of rubbers (e.g., liquid polybutadiene and random copolymers), or thermoplastics (e.g., polyethersulphone or polyetherimide in epoxy matrices or poly(vinyl acetate) in unsaturated polyesters), as impact modifier (epoxies), or low-profile additives (polyesters). The modifier-rich phase may be characterized by the presence of a new a peak (Fig. 11.10). But on occasions there may be superposition of peaks and the presence of the modifier cannot be easily detected by these techniques. If part of the added polymer is soluble in the thermoset matrix, its eventual plasticizing effect can be determined from the corresponding matrix Tg depletion, and the... 

Various patents on the homopolymerization of BD in the presence of styrene are available [581-590]. According to these patents, St is used as a solvent in which BD is selectively polymerized by the application of NdV/DIBAH/EASC. At the end of the polymerization a solution of BR in St is obtained. In subsequent reaction steps the unreacted styrene monomer is either polymerized radically, or acrylonitrile is added prior to radical initiation. During the subsequent radical polymerization styrene or styrene/acrylonitrile, respectively, are polymerized and ris-l,4-BR is grafted and partially crosslinked. In this way BR modified (or impact modified) thermoplast blends are obtained. In these blends BR particles are dispersed either in poly(styrene) (yielding HIPS = high impact poly(styrene) or in styrene-acrylonitrile-copolymers (yielding ABS = acrylonitrile/butadiene/ styrene-terpolymers). In comparison with the classical bulk processes for HIPS and ABS, this new technology allows for considerable cost reductions... 

Improvements of clarity in transparent materials can be obtained in a variety of ways. If unplasticized poly(vinyl chloride) includes an impact modifier with refractive index matching that of the polymer it is possible to use thinner sections and so increase clarity, rates of output, and gloss. With polyolefins, similar results may be achieved by including a nucleating agent to accelerate crystallization even polypropylene, which normally is translucent, thus can be made in an almost clear form. 

Polymer Engineering and Science 41, No.3, March 2001, p.575-83 IZOD IMPACT STRENGTH OF A PRODUCT MOLDED OF POLY(VINYL CHLORIDE)/ IMPACT MODIFIER CONTAINING VOIDS (VOID MOD)... 

STUDY OF ADDITIVE COMPATIBILITY WITH POLY(VINYL CHLORIDE). I. DYNAMIC MECHANICAL ANALYSIS (DMA) OF IMPACT MODIFIED RIGID PVC CONTAINING ESTER LUBRICANTS... 

We have tested the following polymers polycarbonate (PC), poly-carbonate/4% polyethylene blend (PC/PE), poly (ethylene terephthal-ate) (PET), ABS, and impact modified polystyrene (HIPS). All materials except PC were compression molded into nominal Vs-inch sheets. The PC used was an Vs-inch extruded sheet heat-treated in a manner previously described (22). These PC specimens were considered to be... 

Effects of additives in the matrix were observed by substituting for methyl methacrylate a poly (methyl methacrylate) homopolymer with a solution molecular weight of 950,000, a vinylidene fluoride copolymer (Pennwalt s Kynar 7201), and a methacrylate-butadiene-styrene impact modifier (Marbon s Blendex BTA IIIN). Concentrations were 2% on the total dispersion volume. The same additives were studied at the same volume concentration in the dispersed phase. Barium sulfate (Whittaker, Clark, and Daniels Barytes No. 91), a commonly used additive for radiopacity, was also studied in the dispersed phase. Responses were observed by the test methods described below. 

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