Rubber particle size

Compo- sition number Resin type/parts per 100 parts of mbber (phr) Sulfur (phr) Y Method of preparation Cross- link density, r/2 (moles X 10 per ml of mbber) Rubber particle size (pm) Young s modulus (MPa) Stress at 100% strain (MPa) Tens. str. (MPa) UlL elong. (%) Tens. set (%)... 

Rubber particle size (/i.m) Large particles in blends (%) Rubber phase volume fraction Notched Izod impact strength ft. Ibs/in. Gloss... 

Similarly, the elongation at break and the tensile strength of the crosslinked PPO are lower than those of PCL, which explains the decrease in elongation at break and decrease in tensile strength of the TPVs as shown in Fig. 11. By increasing Tcure, not only the rubber particle size decreases, but also the connectivity increases. 

Fig. 11 Effect of on tensile properties for PCL/PPO blends containing 60% of PCL (numbers indicate rubber particle size arrows indicate the respective properties)...

In another system, miscible blends of PE and lauryl methacrylates (LMA) were in situ polymerized/crosslinked to yield submicrometer rubber particle sizes ranging from 70 to 400 nm [55]. Divinyl benzene (DVB) was used as a crosslinking system for LMA (rubber precursor). Typical TPV morphologies consisting of a crosslinked PLMA rubber dispersion (gel content >90%) in a PE matrix and, consequently, typical TPV solid-state properties are obtained. 

Most ABS is made by emulsion polymerization. A polybutadiene or nitrile rubber latex is prepared, and styrene plus acrylonitrile are grafted upon the elastomer in emulsion. The effect of rubber particle size in ABS graft copolymer on physical properties is the subject Chapter 22 by C. F. Parsons and E. L. Suck. Methyl methacrylate was substituted for acrylonitrile in ABS by R. D. Deanin and co-workers. They found a better thermoprocessability, lighter color, and better ultraviolet light stability. 

Rubber Particle Size and Shape. If rubber particles act as crack or craze branch points along an advancing crack in matrix polymer, impact strength should depend on the frequency with which branch points are encountered. If C = rubber phase volume fraction, N = number of dispersed particles, and d = average particle diameter, N C -r (P, N is maximized as C increases or d decreases. The probability of an advancing crack hitting a particle as it advances an incremental distance is proportional to cross sectional area Nd2, which equals C/d. Again, C... 

Table V. Effect of Rubber Particle Size and Shape in Impact Poly S/AN + 20 wt % Poly B/AN...

Prepolymerization may be carried out in the presence of water (7), which aids in heat transfer. At the same time, however, because of the low viscosity of water compared with the polymeric phase, agitation within the organic phase is less intensive and therefore must be accelerated or prolonged to arrive at a rubber particle size and gel content equivalent to that obtained during bulk agitated prepolymerization. 

The rubber particle size in the final product increases several fold if the prepolymerization is carried out in the presence of a dilute aqueous solution of an alkane sulfonate or polyvinyl alcohol in place of pure water. The addition of a surface-active agent converts the coarsely dispersed oil-water mixture—obtained as above in the presence of pure water—into an oil-in-water emulsion. In this case even prolonged stirring during prepolymerization does not decrease the rubber particle size appreciably in the final product. The stabilization of the droplets of the organic phase in water by the emulsifier obviously impedes or prevents agitation within the polymeric phase. Figure 1 shows the influence of these three prepolymerization methods (under otherwise equal reaction conditions) on the dispersion of rubber particles in polystyrene. 

As explained above the rubber particle size in the final product is a measure for the rate of agitation—under otherwise equal reaction conditions—within the rubber-polystyrene-styrene solution during prepolymerization. Figure 1 shows that agitation is least effective if the organic... 

Figure 8.8 SEM photograph of a fully-cured rubber-modified epoxy network. The rubber CTBN (18 wt% AN) was also pre-reacted with a large excess of DGEBA and then introduced (15 wt% initial CTBN) in DGEBA - 4,4 diamino -3,3 -dimethyldicyclohexylmethane, 3 DCM, precured at 50°C (time > tgei) and postcured at 190°C. Rubber particle sizes are smaller than in Fig. 8.7. (From LMM Library). 

Cavitation in the rubber particles of PS/high-impact PS (HIPS) was also identified as a heterogeneous nucleation site, using batch-foam processing [15, 16]. The experimentally observed cell densities as a function of the temperature, the rubber (HIPS) concentration, the rubber particle size, and saturation pressure were found to be in good agreement with the proposed nucleation model. Similar nucleation mechanisms of elastomeric particles were claimed for acrylic and di-olefinic latex particles in various thermoplastics [17, 18]. 

Presented in this paper are the results of an investigation concerning the link between structure and properties of rubber-toughened plastics. An attempt has been made to assess the importance of the spatial distribution of rubber particles in terms of their effectiveness in controlling craze initiation and growth. Also studied in particular were the effects of rubber particle size on the mechanical properties of HIPS materials. A... 

Van Henten, at the Shell Plastic Laboratories (II), showed that styrene-butadiene block polymers can be blended with commercial HIPS to upgrade its impact strength to 5.8 ft-lbs/inch. Childers, at Phillips Petroleum (12), blended commercial polystyrene with block polymers in a Brabender plastograph. To control rubber particle size he added a peroxide during the blending operation, thereby creating crosslinks. With this technique he achieved an impact strength of 5.9 ft-lbs/inch. 

Rubber Particle Size and Dispersion. Particle size is important for impact. If the size distribution is wide—i.e., 1-20 microns—the large particles represent a less efficient use of the toughness of the rubber and tend to reduce tensile strength and to give poorer surface finish when compared with a narrow particle size distribution—i.e., 1-5 microns (4). 

The graft rubber particle sizes for these MBAS and SA impact polymers are nearly equivalent hence they can be compared directly. Other variables which may affect strength properties such as the craze size of the resin matrix, the interphase adhesion, molecular weights and... 

Monomer compositional drifts may also occur due to preferential solution of the styrene in the rubber phase or solution of die acrylonitrile in die aqueous phase (72). In emulsion systems, rubber particle size may also influence graft structure so that die number of graft chains per unit of rubber particle surface area tends to remain constant (73). Factors affecting the distribution (eg, core-shell vs "wart-like" morphologies) of die grafted copolymer on die rubber particle surface have been studied in emulsion systems (74). Effects due to preferential solvation of die initiator by die polybutadiene have been described (75,76). 

Other rubber systems have been commercially successful. Styrene block copolymers yield a HIPS product with a small particle size and provide high gloss. A mixed rubber system consisting of styrene-butadiene block rubber and/or ethylene-propylene diene modified (EPDM) rubber can be blended with the polybutadiene to form bimodal rubber particle size distribution for a... 

Increasing the rubber particle size increases toughness to a point of diminishing returns. 

---