Hardness bulk polymer

Entries on new materials, including re-cyclate plastics, fullerenes, hard-surfaced polymers, dendrimers, transflective materials, rapid prototyping materials, silicone nitride, supercritical fluids, bulk molding compounds, conversion coatings, folic acid, replacements for chloro-fluorocarbons ... 

The furfuryl esters of acrylic and methacrylic acid polymerize via a free-radical mechanism without apparent retardation problems arising from the presence of the furan ring. Early reports on these systems described hard insoluble polymers formed in bulk polymerizations and the cross-linking ability of as little as 2% of furfuryl acrylate in the solution polymerization of methylacrylate121. ... 

The quantity of primary interest in the study of nonuniform fluids is the density profile of the fluid at a surface. Dickman and Hall [28] reported the density profiles of freely jointed hard-sphere chains at hard walls. Their focus was on the equation of state of melts of hard-chain polymers, and they performed simulations of polymers at hard walls because the bulk pressure, P, can be calculated from the value of the density profile at the surface using the wall sum rule ... 

The electron diffraction results support the occurrence of soft-segment crystallinity and a more disordered hard-segment phase in the solvent-cast samples. Moreover, electron diffraction indicates isolated crystalline soft-segment regions persist even in samples of up to 43% hard segment. Electron diffraction is very sensitive to small local fluctuations in the overall structure because the diffraction patterns can be obtained from regions less than 1 /un in diameter and less than. l-/un thick, whereas DSC and WAXS, of course, measure bulk polymer which yields averages over the whole sample. 

In summary, it can be concluded that using nanoindentation hardness measurements on the crack tip, down to penetration depths of 0.8 pm, it is possible to detect very small craze zones in glassy polymers. The microhardnesses for all investigated samples can be divided into three regions (1) the cracked region, (2) the crazed zone and (3) the bulk material. It was also found that the microhardness of the crazed material is larger than the microhardness of the bulk polymer due to the orientation of the polymer chains within the craze fibrils. 

The fact that in these bulk polymer samples no photoisomerization could be detected has to be attributed only to the severe restrictions of the local chain segmental mobility around the chromophore, i. e., it is due to the predominant incorporation of the azochromophoric units in the hard phase the mobility of chain segments within the hard domain is widely suppressed in this system, cousing a nearly complete immobilization of the chromophore in the hard phase. This behaviour is comparable to systems where the photochrome was incorporated in highly crystalline polyamide or polyimide (2,20,21). 

We may consider two extremes in regard to heat effects in the failure of a bulk polymer (1) adiabatic systems and (2) isothermal systems. And we may consider two qualitative extremes with regard to polymer hardness and strength the polymer may be (a) hard and brittle, or (b) soft and tough. Some examples of the four combinations of these extremes are ... 

The bulk polymer obtained after 80 min at 110 C in N2 atmosphere is white, veiy hard and brittle. The texture of a thin film of this polymer looks like a disordered mesophase texture. The polymer is insoluble in all the classical solvents except in the dimethylformamide. It swells in chloroform. The thermogram of this polymer does not exhibit any transition from room temperature until 260 C. 

BCPs [117-121], The concepts discussed above may help to understand the crystallization behavior of bulk polymers as well as that of non-polymeric materials such as pharmaceuticals [122] and inorganic semiconductors [123] confined to nanoporous hard templates. 

Fig. 12. Diagram of fibrillar and bulk phase in hard elastic polymers.

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