Blowing agent enhancers

The effectiveness of blowing agent enhancers are shown in Table 21.4. The blowing agent enhancer with the best flow and fc-factor is di(ethylene glycol) methyl ether. 

J.W. Miller, Blowing agent enhancers for polyurethane foam production, US Patent 6 921779, assigned to Air Products and Chemicals, Inc. (Allentown, PA), July 26,2005. 

Eoams were extruded from low density polyethylene (LDPE) and blends of LDPE with syndiotactic polypropylene (sPP), using isobutane as the blowing agent. The extruded materials were characterised by measurement of dimensional stability at room temperature, density, tensile properties, dynamic stiffness, and crystallinity determined by differential scanning calorimetry. The sPP, with a slow crystallisation rate, did not interfere with the expansion of the LDPE, and enhanced the temperature resistance by in-situ crystallisation. The blends were flexible, dimensionally... 

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. 

A study was made of nucleation in PE foams produced in a counter-rotating extruder using talc powders and masterbatches as nucleating agents and CFG and HCFC blowing agents. The results indicated the importance of shear force in nucleation, as proposed in the lump cavity nucleation model and demonstrated by melt temperature effects observed in these experiments. It was shown that shear enhancement via lump break-up was not a vital mechanism in nucleation. 6 refs. 

The Polymer. Amorphous Polystyrene. All of the expandable polystyrene referred to above is the amorphous type that is obtained by free radical initiation. This polymer is completely noncrystalline, and in the absence of impurities such as monomer and blowing agent it exhibits a glass-transition temperature of about 100°C. Both the rate of expansion and the extent of expansion are enhanced by reducing molecular weight, but the foam becomes less resistant to collapse on further steaming (63). Other polymeric modifications are discussed below. 

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. 

Polymeric foams have a closed-shell structure approximately 10 pm in diameter, with a cell density between 10 and 10 cells cm. These foamed materials have superior properties to their unfoamed counterparts in terms of enhanced ratio of flexural modulus to density and impact strength [58]. High-pressure CO2 offers a particularly attractive alternative to traditional blowing agents because of its environmentally benign nature and relatively low cost The phasing out of ozone-depleting substances associated with the Montreal Protocol acts as... 

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