Solidification time

Dicyclopentadiene is also polymerized with tungsten-based catalysts. Because the polymerization reaction produces heavily cross-Unked resins, the polymers are manufactured in a reaction injection mol ding (RIM) process, in which all catalyst components and resin modifiers are slurried in two batches of the monomer. The first batch contains the catalyst (a mixture of WCl and WOCl, nonylphenol, acetylacetone, additives, and fillers the second batch contains the co-catalyst (a combination of an alkyl aluminum compound and a Lewis base such as ether), antioxidants, and elastomeric fillers (qv) for better moldabihty (50). Mixing two Uquids in a mold results in a rapid polymerization reaction. Its rate is controlled by the ratio between the co-catalyst and the Lewis base. Depending on the catalyst composition, solidification time of the reaction mixture can vary from two seconds to an hour. Similar catalyst systems are used for polymerization of norbomene and for norbomene copolymerization with ethyhdenenorbomene. 

The solidification time for an amorphous polymer will be determined by ... 

Productivity is directly related to cycle time. There usually is considerable common knowledge about a geometry and process conditions that will provide a minimum cycle time. Practices such as using thinner wall sections, cold or hot runners for TPs or hot or cold ones for TSs narrow sprues and runners, the optimal size and location of coolant (or heat) channels, and lower melt or mold heat, will decrease the solidification time reducing the cycle time. 

Droplet Formation in Water Atomization. In water atomization of melts, liquid metal stream may be shattered by impact of water droplets, rather than by shear mechanism. When water droplets at high velocities strike the liquid metal stream, some liquid metal fragments are knocked out by the exploding steam packets originated from the water droplets and subsequently contract into spheroidal droplets under the effect of surface tension if spheroidization time is less than solidification time. It is assumed that each water droplet may be able to knock out one or more metal droplet. However, the actual number of metal droplets produced by each water droplet may vary, depending on operation conditions, material properties, and atomizer designs. 

Freezing Number =[AHm l-fs)+CpLXr 7m0pLDl 6aAtl Tw) Compare solidification time to impact time Matson etal.[4091... 

Figure 4.17. Dependences of the solidification time on the parameter cu at different mold temperatures. Solid lines - for the initial temperature To = 40°C dotted lines - for To = 70°C.

The spacing, k, between secondary dendrite arms has been shown to increase with solidification time, If,... 

Although all polymer processes involve complex phenomena that are non-isothermal, non-Newtonian and often viscoelastic, most of them can be simplified sufficiently to allow the construction of analytical models. These analytical models involve one or more of the simple flows derived in the previous chapter. These back of the envelope models allow us to predict pressures, velocity fields, temperature fields, melting and solidification times, cycle times, etc. The models that are derived will aid the student or engineer to better understand the process under consideration, allowing for optimization of processing conditions, and even geometries and part performance. 

The distilled solvents (the mixture of toluene and butanol) are sent into cooler 10 to condense and are collected in receptacle 11, from where they are poured into collector 12. The finished varnish is analysed to determine solid residue (40-55%), drying time (not more than 40 minutes at 125 5 °C) and solidification time (not more than 60 minutes) after that it is sent from the tank into settling box 13. In the settling box the finished varnish is separated from mechanical impurities at ambient temperature, purified in... 

Solidification range defined as liqui-dus - solidus temperature, °C Solidification time defined as the time corresponding to the solidification range, s... 

Solidus temperature, °C Solidification range, °C Solidification time, s... 

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