Master batches

In the most common production method, the semibatch process, about 10% of the preemulsified monomer is added to the deionised water in the reactor. A shot of initiator is added to the reactor to create the seed. Some manufacturers use master batches of seed to avoid variation in this step. Having set the number of particles in the pot, the remaining monomer and, in some cases, additional initiator are added over time. Typical feed times ate 1—4 h. Lengthening the feeds tempers heat generation and provides for uniform comonomer sequence distributions (67). Sometimes skewed monomer feeds are used to offset differences in monomer reactivity ratios. In some cases a second monomer charge is made to produce core—shell latices. At the end of the process pH adjustments are often made. The product is then pumped to a prefilter tank, filtered, and pumped to a post-filter tank where additional processing can occur. When the feed rate of monomer during semibatch production is very low, the reactor is said to be monomer starved. Under these... 

Pigments are available ia a number of commercial forms including dry powders (either surface treated or untreated), presscakes, flushed colors (thick pastes), fluidi2ed dispersions (pourable pastes), resia predispersed pigments (powders), and plastic color concentrates or master batches (granules) (see PiGLffiNTDISPERSIONS). 

Most peroxides of the appropriate thermal stabiUty for mbber cross-linking are Hquids or low melting soHds which, in addition to the 100% active product, are offered adsorbed on inert, free-flowing carriers or in polymeric master batches for easy handling. Peroxides (qv) are oxidizing materials and should be stored away from other mbber chemicals and kept away from heat sources. 

Centralized make-up of toxic chemicals in master batches for transfer in sealed containers or impermeable bags. 

Dust from carbon black Master batches Local exhaust ventilation Totally enclosed systems Not by careful handling alone... 

Compounding Dust Local exhaust ventilation Master batches Preweighed, sealed bags Dust-suppressed chemicals Care in handling... 

One of the most important solution blend polymers is high-styrene resin, which is manufactured by several companies worldwide. This is a latex blend of high-styrene rubber and normal styrene butadiene rubber. The different high-styrene master batches are available in the world as ... 

Alkanesulfonates are an important internal antistatic agent for polystyrene (PS) as well. If it is not possible to apply the pure active surfactant with the intended processing machine, the use of a master batch of alkanesulfonates and an appropriate polystyrene product is recommended. The addition of alkanesulfonates in amounts greater than 0.3 phr can cause hazing also in transparent PS articles. The antistatic effect of alkanesulfonates in PS is demonstrated in Fig. 41. 

Another example of the combination of toughening and fire retardant-enhancement is the use of TPE as a carrier for master batch of FR-803 (TBS). This master batch was not only an efficient toughener for SMA but also permitted a UL-94 VO rating, unachievable for SMA/TBS alone (Fig. 6). 

It should be emphasized that only the addition of TPE/FR-803 master batch provided an efficient combination of toughening and fire retardant enhancement. The addition of TPE alone to SMA/FR-893, although providing a certain increase of impact properties, did not enhance the fire retardant (Fig. 7, Table 8). 

COMPOUNDING DIRECT COMPOUNDING OF ALL COMPONENTS VIA MASTER BATCH... 

Fig. 7. Comparison between the influence of the addition of TPE to SMA/FR-803 and of TPE/FR-803 master batch to SMA.

BR is incompatible with CR because of the large difference in polarity. Mingyi et al. have studied their compatibUization in the presence of a styrene-butadiene-styrene block (SBS) copolymer [30]. The blends were prepared by blending the two mbbers separately at approximately 75°C. The master batch of the BR compound contained 1 part of sulfur, 2 parts of copolymer, 1.5 parts of TMTD, 5 parts... 

Preparation of Emulsions. The entire aqueous phase was stirred until all solids were dissolved. Sufficient water was withheld from the formulation so small volumes of experimental and control components could be added to emulsion subsamples. Sulfuric acid (1 N) was added to the aqueous phase to decrease the pH to 5.7. The two phases in separate containers were blanketed with nitrogen, sealed, and heated to 75 in an 80 water bath (about 30 minutes). The hot oil phase was stirred slowly and blanketed with nitrogen, then the hot aqueous phase was quickly added while stirring. The emulsion was blanketed with nitrogen and slowly stirred (about 2 hours) in the stoppered container until ambient temperature ( 25 ) was reached. Subsamples of the master batch were removed for the addition of experimental components and stored in 1-oz containers. The containers had been washed with hot tap water, deionized water, and methanol, then dried at 120 . 

EXPERIMENT ID SUBMITTER S NAME OPERATOR S INITIALS FINAL TEST TEMPERATURE FLUID TYPE POLYMER LDT NO. MASTER BATCH NO. 

The additives can be added during the polymerisation (either in the form of a reactive monomer or as an inert material — advantages include better dispersion and increased retention), but they are usually added immediately postpolymerisation of the polymer and extruded with the polymer. Often a concentrated mix with the plastic (master-batch) is prepared by the plastic manufacturer and this can be sold to the fabricators to be added during subsequent processing. 

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