Other components of formulation

The previous section contains example of ionic interaction between polymers and fdlers. Other two examples illustrate manufacture of reaction injection molding, RIM, pol5mrethanes which contain internal mold release , IMR, agent capable to eliminate adhesion without need for addition of mold release agent. Using amine modified polyol, wetting, and bonding witii mold was reduced to produce self-release parts.  

Typical additives such as pigments, lubricants, and plasticizers improve mold release properties. The action of these additives seems to be related to mold fin- 

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There are several factors which determine the results of impact modification. They include PVC molecular weight, condition of material surface, materials thickness, temperature of service, type and structure of impact modifier, its particle size and concentration, UV degradation and stabilization of impact modifier, method of incorporation (dispersion mechanism), shell thickness of core-shell impact modifiers, interaction with other components of formulation (fillers, ther-... 

Also, other components of formulation may influence performance of impact modifiers. Fillers were found to improve impact properties in conjunction with impact modifiers.Addition of heat distortion additives increases impact... 

Antiblocking is an action, usually carried out by reformulation (addition of antiblocking agent(s)), which aims at reduction of forces of adhesion between the materials in contact. Other components of formulation and/or physical parameters are essential and these are considered diroughout the entire book. 

Polydimethylsiloxane is the most common release agent and it is also used in slip applications. The major drawback of sihcone oil use is its effect on adhesion and paintability. Modified polydimethylsiloxanes seem to be one of the solutions to these problems. There is a laige number of modifications, which are most frequently either block copolymers (the other than siloxane block influences compatibility with host polymers), or polymers having different functional groups, which may react with other components of formulation (mostly matrix polymer). 

The dispersion and incorporation processes of fillers and antiblocking additives are discussed in other sources. Oiganic antiblocking and slip additives, solids of low melting temperature, can be mixed with other components of formulation without any special difficulties, but they are usually incompatible widi polymers, and as such, may easily separate or form concentration gradients if left without mixing. For this reason, the process of their addition must include homogenization just before material formation into its final shape. 

The additive may be consumed by chemical reaction or absorption. It is also possible that the additive competes with other components of formulation for coating of metal surface. This will produce inadequate properties of surface. Antiblocking additives are implicated in absorption of the additive, and in the case of problems, they are the most likely suspect subjected to laboratory testing and scrutiny. Typical methods include differential scanning calorimetry, DSC, study of 1 1 mixture of the additive components to establish potential interaction, capillary rheometry of formulation to determine effect of the additive on rate of flow, and full scale extrusion testing. Figure 10.35 shows the effect of antiblocking addi-... 

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