Permanently porous polymer resins derived from multifunctional (meth)acrylate monomers have been prepared by suspension polymerization. The dry state porosity characteristics have been evaluated using N2 sorption and Hg intrusion porosimetry, and the results correlated in terms of the three-dimensional cohesion parameter, δ t , of the polymers and porogens. The pore size distributions of almost all resins cover a broad range from micro- through meso- to macropores. The porosity data had to be computed from the adsorption branches of the N2 sorption isotherms, since an artifact arises in the pore size distributions if derived from the corresponding desorption data. The artifact is attributed to a percolation process in the desorption mechanism. The correlation of porosity data (e.g., the Brunauer, Emmett, and Teller (BET) surface area and the Barret, Joyner, and Halenda (BJH) average pore radius) with the nature of the porogen was found to be very limited if the one-dimensional Hildebrand solubility parameter, δ, only is used. However, by application of a group contribution method due to Hoftyzer−Van Krevelen and Hoy, three-dimensional cohesion parameters, δ t , and the porogen−polymer affinity parameters, d 0, could be calculated. Using the latter as the basis for a new correlation the N2 sorption BET computed surface areas of resins show an inverse proportional relationship with d 0, while BJH average pore radii show a proportional relationship.

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Long-chain branching (LCB) is known as a suitable method to increase the melt strength behavior of linear polypropylene (PP), which is a fundamental weakness of this material. This enables the modification of various properties of PP, which can then be used—in the case of PP recyclates—as a practical “upcycling” method. In this study, the effect of five different peroxides and their effectiveness in building LCB as well as the obtained mechanical properties were studied. A single screw extruder at different temperatures (180 and 240 °C) was used, and long-chain branched polypropylene (PP-LCB) was prepared via reactive extrusion by directly mixing the peroxides. The peroxides used were dimyristyl peroxydicarbonate (PODIC C126), tert-butylperoxy isopropylcarbonate (BIC), tert-Butylperoxy 2-ethylhexyl carbonate (BEC), tert-amylperoxy 2-ethylhexylcarbonate (AEC), and dilauroyl peroxide (LP), all with a concentration of 20 mmol/kg. The influence of the temperature on the competitive prevalent reactions of degradation and branching was documented via melt mass-flow rate (MFR), rheology measurements, and gel permeation chromatography (GPC). However, via extensional rheology, strain hardening could be observed in all cases and the mechanical properties could be maintained or even improved. Particularly, PODIC C126 and LP signaled a promising possibility for LCB in this study.