Stiffness balance

Reinforcement of polypropylene with mica provides outstanding flexural modulus and heat deflection temperature, minimizes warpage, and gives good dimensional stability. Often, however, impact properties are decreased. A paper given to the SPE Polyolefins X Conference in 1997 (31) focused on improvement of the impact-stiffness balance of mica-reinforced polypropylene by use of additives. 

Zilg, C. Mulhaupt, R. Finte, J. Morphology and toughness/stiffness balance of nanocomposites based upon anhydride-cured epoxy resins and laywed silicates. Macro-mol Chem. Phys. 1999, 200, 661-670. 

One should always strive for stiffness balance between the members being joined together, whether by adhesive bonding or mechanical fastening. (The designs in Fig. 2 deviated slightly from this goal but only because there was yet another failure mode, in the adherends rather than the adhesive, which, left... 

There are no tensile normal stresses where the skin ends, so peel is less of a problem there than at the other end. but whatever problem there is should be taken ctne of by appropriate peel stress relief. The tapering does not affect the equality of load transfer at each end of stiffness-balanced joints it merely redistributes it and reduces both the peak peel and shear stresses in the process, as explained in ref, [10],... 

The basic questions BASF attempted to answer with the study are valid ones. Do mPPs offer a better impact and stiffness balance Are claims of higher crystallinity justified To get some answers, Grasmeder tested Novolen M(mPP) against other Novolen ZN PP grades. 

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