Elastomers modifiers

Elastomeric state Elastomer modifiers Elastomer process Elastomers... 

In the early stages of development of polypropylene rubbers, particularly butyl rubber, were used to reduce the brittleness of polypropylene. Their use declined for some years with the development of the polypropylene copolymers but interest was greatly renewed in the 1970s. This interest has been centred largely around the ethylene-propylene rubbers which are reasonably compatible in all proportions with polypropylene. At first the main interest was with blends in which the rubber content exceeded 50% of the blend and such materials have been designated as thermoplastic polyolefin elastomers (discussed in Section 11.9.1). There is also increasing interest in compounds with less than 50% rubber, often referred to as elastomer-modified thermoplastics. It is of interest to note... 

Such rubbery and thermoplastic polymers may be blended in any proportion, so that on one hand the product may be considered as a thermoplastic elastomer, and on the other as an elastomer-modified thermoplastic. There is, furthermore, a spectrum of intermediate materials, including those which might be considered as leather-like. In this area the distinction between rubber and plastics material becomes very blurred. 

In common with other polymers the polycarbonates have been blended with other polymers in recent years. The most well-known blends are those with ABS but more recently elastomer-modified grades have made their appearance, some of which may be copolymers (See Section 20.8). 

A large number of grades is available, one supplier alone offering about 40, including unreinforced, glass- and carbon-fibre reinforced, mineral filler reinforced, impact modified, elastomer modified, flame retardant and various combinations of the foregoing. 

Silicone rubber filled with microspheres and reinforced with a plastic honeycomb Polybutadiene-acrylonitrile elastomer modified phenolic resin with a subliming powder... 

W. A. Romanchick, J. E. Sohn, and J. F. Geibel Synthesis, Morphology, and Thermal Stability of Elastomer-Modified Epoxy Resin, in ACS Symposium Series 221 — Epoxy Resin Chemistry II, R. S. Bauer (ed.), American Chemical Society, Washington DC, 1982, pp. 85-118. 

Elastomer impression materials, 8 327 Elastomer-modified epoxy resins, 10 436 Elastomer-modified epoxies, 10 375-376 Elastomer production, tetrahydrofurfuryl alcohol in, 12 279... 

Bascom, W.D., Cottington, R.L., Jones, R.L. Peyser, P. (1975). The fracture of epoxy and elastomer modified epoxy polymers in bulk and as adhesives. J. Appl. Polym. Sci. 19 2545-2562. 

The structure of crystalline polymers may be significantly modified by the introduction of fillers. All aspects of the structure change on filling, crystallite and spherulite size, as well as crystallinity, are altered as an effect of nucleation [9]. A typical example is the extremely strong nucleation effect of talc in polypropylene [10,11], which is demonstrated also in Fig. 2. Nucleating effect is characterized by the peak temperature of crystallization, which increases significantly on the addition of the filler. Elastomer modified PP blends are shown as a comparison crystallization temperature decreases in this case. Talc also nucleates polyamides. Increasing crystallization temperature leads to an increase in lamella thickness and crystallinity, while the size of the spherulites decreases on... 

Yee, A. F. and Pearson, R. A. Toughening Mechanisms in Elastomer Modified Resins , NASA Contractor Report 3718, 1983... 

It is obvious from these data that CTBN (the carboxyl terminated butadiene-acrylonitrile copolymer) is the most effective modifier, and therefore it was selected for further study. As the concentration of the elastomer was increased to levels up to 100 parts, the impact also increased. The data in Table II show that the room temperature impact of ERL-4221 increased from 40 inch-lbs to greater than 320 inch-lbs by adding 100 phr or 33 wt % of CTBN. At very low temperatures ( —160°F) the impact of the system modified with 60 parts, or 23 wt %, of CTBN was 120 inch-lbs. These impact improvements appear to be directly proportional to the concentration of the elastomer modifier. 

Effect of Molecular Configuration of Elastomer. The extent of the impact and strength improvements of ERL-4221 depends on the chemical structure and composition of the elastomer modifier. The data shown in Table I indicate that the carboxyl terminated 80-20 butadiene-acrylonitrile copolymer (CTBN) is the most effective toughening and reinforcing agent. The mercaptan terminated copolymer (MTBN) is considerably less effective as far as tensile strength and heat distortion temperature are concerned. The mercaptan groups are considerably less reactive with epoxides than carboxyls (4), and this difference in the rate of reaction may influence the extent of the epoxy-elastomer copolymerization and therefore the precipitation of the rubber as distinct particles. 

ABA ABS ABS-PC ABS-PVC ACM ACS AES AMMA AN APET APP ASA BR BS CA CAB CAP CN CP CPE CPET CPP CPVC CR CTA DAM DAP DMT ECTFE EEA EMA EMAA EMAC EMPP EnBA EP EPM ESI EVA(C) EVOH FEP HDI HDPE HIPS HMDI IPI LDPE LLDPE MBS Acrylonitrile-butadiene-acrylate Acrylonitrile-butadiene-styrene copolymer Acrylonitrile-butadiene-styrene-polycarbonate alloy Acrylonitrile-butadiene-styrene-poly(vinyl chloride) alloy Acrylic acid ester rubber Acrylonitrile-chlorinated pe-styrene Acrylonitrile-ethylene-propylene-styrene Acrylonitrile-methyl methacrylate Acrylonitrile Amorphous polyethylene terephthalate Atactic polypropylene Acrylic-styrene-acrylonitrile Butadiene rubber Butadiene styrene rubber Cellulose acetate Cellulose acetate-butyrate Cellulose acetate-propionate Cellulose nitrate Cellulose propionate Chlorinated polyethylene Crystalline polyethylene terephthalate Cast polypropylene Chlorinated polyvinyl chloride Chloroprene rubber Cellulose triacetate Diallyl maleate Diallyl phthalate Terephthalic acid, dimethyl ester Ethylene-chlorotrifluoroethylene copolymer Ethylene-ethyl acrylate Ethylene-methyl acrylate Ethylene methacrylic acid Ethylene-methyl acrylate copolymer Elastomer modified polypropylene Ethylene normal butyl acrylate Epoxy resin, also ethylene-propylene Ethylene-propylene rubber Ethylene-styrene copolymers Polyethylene-vinyl acetate Polyethylene-vinyl alcohol copolymers Fluorinated ethylene-propylene copolymers Hexamethylene diisocyanate High-density polyethylene High-impact polystyrene Diisocyanato dicyclohexylmethane Isophorone diisocyanate Low-density polyethylene Linear low-density polyethylene Methacrylate-butadiene-styrene... 

Characteristic functions and the representative structures of plastics additives providing marketable and durable materials are included in this chapter. Types of additives for plastics used in contact with food are listed in Table 3-1. Similar additives as for PS are used for elastomer-modified plastics forming multilayer systems (blends) and used rather exceptionally in contact with food, such as high-impact polystyrene (HIPS) or acrylonitrile-butadiene-styrene polymer (ABS). Some of the additives, stabilizers in particular, are very reactive and are present in the plastic matrix in a chemically transformed form. 

The toughening mechanism of elastomer modified epoxy systems is different from that of flexibilized epoxy systems and can be used in combination with them. Flexibilized epoxy systems reduce mechanical damage by a reduction in modulus or plasticization of the adhesive. This allows stress to be relieved through distortion of the adhesive, but it also generally results in a lowering of the adhesive s glass transition temperature with an accompanying reduction in heat and chemical resistance. 

CTBN modified bisphenol F resin (EPON 58003) Elastomer modified bisphenol A resin 25 100 ... 

EPON 58003 285-330 1,500-3,000 at 52°C CTBN elastomer modified bisphenol F resin Resolution... 

EPON 58135 208-220 250-500 at 52°C Elastomer modified bisphenol A specifically designed for adhesion to vinyl Resolution... 

Urethane RIM Elastomers Modified with Plasticizer. The standard RIM elastomer A (Table I) containing 54.8% of rigid segments was modified with plasticizer, tributyl phosphate, as follows elastomer B with 5%, elastomer C with 10%, and elastomer D with 15%. The composition of all four of these elastomers is presented in Table III. 

Chen et al. (12) showed that phase separation in elastomer-modified epoxies can also be detected with much more sensitivity using small-angle X-ray scattering (SAXS). Then, the choice of the cloud point as a criterion for detecting the beginning of phase separation can be discussed. We have not performed SAXS studies on our systems because phase separation is much faster in thermoplastic-modified epoxy and the scanning time is too long. 

Elastomer-Modified Vinyl Ester Resins Impact Fracture and Fatigue Resistance... 

VERs are available as both rigid and flexible epoxy resins. The flexible epoxy resins generally have a depressed glass-transition temperature, Tg, and inferior chemical resistance. Nitrile-rubber-modified VER (I) appeared on the market in the mid- to late 1970s. These elastomer-modified VERs show improved fatigue resistance over unmodified VER (2). 

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