In situ molding

New and promising composite pre-form technology which can be in situ molded with unsaturated polyester resins to further improve structure and performance have been demonstrated. 

In the early 1990s, yet another category was developed. These rigid macroporous organic polymer monoliths were formed by a very simple in situ molding process in which a liquid mixture of monomers and solvents was polymerized under carefully controlled conditions and immediately used within a closed tube or similar container. Many review artieles describing various aspects of these materials have been published during the years since their inception. ... 

To complicate matters further, in situ mold release is commonly used to prevent molded composite parts from sticking in the mold. The mold release is formulated to migrate to the surface of the part during molding, where it can prevent the part from... 

FIGURE 19.5 Stack and ampoule assembly of a lead/fluoboric acid/Iead dioxide reserve battery supported by potting in epoxy in a molded case (left) and by in situ molding using a reaction impingement molded polyurethane foam (right). (Courtesy of U.S. Department of the Army.)... 

Continuous porous polymer rods have been prepared by an in situ polymerization within the confines of a chromatographic column. The column is filled with glycidyl methacrylate and ethylene dimethacrylate monomer mixtures, cyclo-hexanol and dodecanol diluents, and AIBN initiator. They are then purged with nitrogen, stopped, and closed with a silicon rubber septum. The polymerization is allowed to proceed for 6 hr at 70°C with the column acting as a mold (47). 

Table 4 also reports dependence of the mechanical tensile properties of the samples on the processing conditions. The highest tensile properties of sample 1, injection molded with a lower melt temperature and a lower volume flux, are attributed to the highest degree of fibrillation of the TLCP fibers, as shown in Fig. 12, by so-called in situ reinforcement. 

According to the composite theory, tensile modulus of fiber reinforced composites can be calculated by knowing the mechanical constants of the components, their volume fraction, the fiber aspect ratio, and orientation. But in the case of in situ composites injection molded, the TLCP fibrils are developed during the processing and are still embedded in the matrix. Their modulus cannot be directly measured. To overcome this problem, a calculation procedure was developed to estimate the tensile modulus of the dispersed fibers and droplets as following. 

The second interesting sidelight was the conclusion that no relationship existed between in situ hydraulic conductivity and either molding water content of the soil or the dry density of the compacted soil. 

An important variant of the in situ process is foaming within a flexible cover. As the foam expands, it forces the cover outwards to conform to the interior shape pf a mold. We make extensive use of this process to make seat cushions for automobiles and office furniture. 

Aeropak process—simultaneous blow-molding and inner-surface fluorination of polymeric containers—is the most well-known example of an in-situ treatment process. 

This article is an overview of the novel technology of self-reinforced LCPs with polyesters, poly(ethylene terephthalate) (PET) and poly(ethylene naphtha-late) (PEN) [10-13, 21, 23], LCP/polyester blends in a polyester matrix form in situ fibrils which improve the mechanical properties. LCPs have an inherently low melt viscosity, and provide LCP/polyester blends that effectively lower the melt viscosity during melt spinning [24], and fast injection-molding cycles. The miscibility between the LCP and polyesters can be controlled by the degree of transesterification [25] in the reactive extrusion step, and fibril formation in LCP-reinforced polyester fibers has been studied. 

Polyurethanes are useful in numerous applications such as reaction injection molding, rigid and flexible foams, coatings and adhesives. However, due to the high reactivity of the isocyanate group [96], yielding either dimers, via self-condensation or a carbamate via the reaction with an alcohol, the A,jB-monomers have to be produced in-situ in the reaction vessel. 

Clean sweep Fallen leaves need to be swept from the lawn to keep It healthy, but should never be burned pile or bag them up to make leaf mold see pp.44-45). You can fashion a besom, or lawn broom, yourself by binding a bundle of twiggy prunings to a wooden shaft. An alternative If leaf-fall is not too heavy Is to mow over the leaves and leave them, shredded, In situ worms will soon take them down into the soil. 

In situ (Latin for in the place ) polymerization means the fabrication of a polymer network directly in the finally desired shape and geometry. In the context of monolithic separation columns, the term in situ is referred to the polymerization in the confines of a HPLC column or a capillary as mold. 

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