Silicone blocks into polycarbonates

Toughness Enhancement by Introduction of Silicone Blocks into Polycarbonates of Bisphenol Acetone and Bisphenol Fluorenone... 

A comparison of Figures 7a and 7b shows that the resistance to craze initiation is lowered more than the resistance to plane strain crack initiation (i.ecraze breakdown) by introducing silicone blocks into BPA polycarbonate. 

Two families of transparent polycarbonate-silicone multiblock polymers based on the polycarbonates of bisphenol acetone (BPA) and bisphenol fluorenone (BPF) were synthesized. Incorporation of a 25% silicone block in BPA polycarbonate lowers by 100°C the ductile-brittle transition temperature of notched specimens at all strain rates silicone block incorporation also converts BPF polycarbonate into a ductile plastic. At the ductile-brittle transition two competing failure modes are balanced—shear yielding and craze fracture. The yield stress in each family decreases with silicone content. The ability of rubber to sustain hydrostatic stress appears responsible for the fact that craze resistance is not lowered in proportion to shear resistance. Thus, the shear biasing effects of rubber domains should be a general toughening mechanism applicable to many plastics. 

Sikdar et al. (2000) developed adsorbent-filled PV membranes for removing VOCs from waste water. These membranes were prepared by dispersing at least one hydrophobic adsorbent uniformly into a polymer matrix. Polymeric membrane was made of rubbery polymer selected from the group consisting of PDMSs, PTMSP, PUs, polycarbonates (PCs), PE-block-polyamides, silicon PCs, styrene butadiene rubber, nitrile butadiene rubber, and ethane-propene terpolymer. The hydrophobic adsorbent was selected from the group consisting of hydrophobic zeolites, hydrophobic molecular sieves, activated carbon, hydrophobic polymer resin adsorbents, and mixtures thereof. 

Very recently. Block et al. [133] reported on optical modulators with ring diameters smaller than 50 pm in a silicon nitride based waveguide system on silicon oxide with a top cladding of an electro-optic polymer, namely AJTB141 chromophore 28% wt into an amorphous polycarbonate polymer. Using Cu electrodes they attained a high frequency modulator with modulation up to 10 GHz with low drive voltage (2.7 Vpp). 

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