Blowing agents physical properties

PS Foams. The eady history of foamed PS is available (244), as are discussions of the theory of plastic foams (245). Foamable PS beads were developed in the 1950s by BASF under the trademark of STYROPOR (246—248). These beads, made by suspension polymerization in the presence of blowing agents such as pentane or hexane, or by post-pressurization with the same blowing agents, have had an almost explosive growth, with 200,000 metric tons used in 1980. Some typical physical properties of PS foams are Hsted in Table 10 (see Foamed plastics). 

Although httle advantage is observed with regard to vulcanizate physical properties (Table 14.54), a benefit is apparent in terms of reduced heat buildup (Figure 14.23). In addition, the antireversion agent provides greater thermal stability in terms of blow-out resistance... 

Much of the research in the last decade confirms and extends this research. The papers provide detailed technology or science, rather than reviewing the bigger picture. This review will concentrate on 12 main areas, allowing space for detailed discussion. It emphasises mechanical and physical properties and modelling, areas which have not been recently reviewed. Blowing agent chemistry and processes are reviewed in (303, a.6). 

Journal of Applied Polymer Science 83, No.2, 10th Jan.2002, p.357-66 MORPHOLOGY AND PHYSICAL PROPERTIES OF CLOSED CELL MICROCELLULAR ETHYLENE-OCTENE COPOLYMER EFFECT OF PRECIPITATED SILICA FILLER AND BLOWING AGENT Nayak N C Tripathy D K Indian Institute of Technology... 

Carbon dioxide gas was used as a physical blowing agent to produce medium density polypropylene foam sheets using a single screw extruder. The mechanical properties of the foam were similar in the machine direction and in the transverse direction. Abetter surface finish and a lower density was produced by using a commercial wrapping film as a cap layer. The process conditions and the die design data are presented and an attempt made to relate them to the product characteristics. 4 refs. 

PE and EVA foams were manufactured by a two-stage heat and chill compression moulding technique, which allowed more efficient utilisation of the platen area than other compression moulding process variants and which was suited to low density foam production. The interrelationships of base polymer type, crosslinking and blowing agent concentrations and physical properties of resultant foams were investigated. 13 refs. 

Disclosed is an ethylene polymer foam structure having enhanced processing and physical properties. The foam structure comprises an ethylenic polymer material and a blowing agent of isobutane and 1,1-difluoroethane. Further disclosed is a process for making the foam structure. 

These comprise an ethylenic polymer and a blowing agent, which contains a primary blowing agent of isobutane and a secondary blowing agent of 1,1,1-trifluoroethane, 1,1,12-tetrafluoroethane or a blend thereof. They exhibit enhanced processing and physical properties. 

Liquid color is not a universal coloring system, but nothing is. It can perform in a variety of processes, in nearly all resins. Liquid is at its best in small percentages, where its distribution in the resin is excellent it does modify physical properties somewhat but enhances some properties. It is excellent for heat-sensitive additives, such as blowing agents. Look into using liquid color as a coloring system the economics may work out favorably. 

---