Comparison of rheological behavior of branched polypropylene prepared by chemical modification and electron beam irradiation under air and N2

Rheological analysis of irradiated crosslinkable and scissionable polymers used for medical devices under different radiation conditions

“…Consequently, its molecular weight decreases considerably leading to important losses in the mechanical and viscoelastic properties (Cerrada et al, 2010). A way to revert this drawback is by adding specific multifunctional and nucleating agents that provide crosslinking reactions during the irradiation process resulting in PP with improved mechanical response and viscoelastic properties (DeNicola et al, 1995;Shukushimaa et al, 2001;Gao et al, 2002, Mousavi S.A. et al 2010.…”

Evaluation of Thermally Induced Degradation of Branched Polypropylene by Using Rheology and Different Constitutive Equations

“…The key problem with processing of conventional linear PP is its low melt strength, which may limit processing window considerably. Thus, it is not surprising that considerable progress has been made to enhance PP melt strength by introduction of long chain branching via different methods such as electron beam radiation [ 1 , 2 , 3 , 4 , 5 , 6 ], gamma radiation [ 1 , 7 , 8 ], UV radiation [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] or utilizing peroxides (usually in presence of multi-functional monomers) [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. It has been reported that branched PPs have a predominantly star-like structure [ 5 , 24 , 25 , 26 , 27 , 28 ], which causes significant extensional strain hardening inducing a so-called “self-healing” effect leading to improved quality of products (for example, wall thickness uniformity or a better foam structure) due to homogeneous deformation in elongational flows [ 28 , 29 , 30 , 31 , 32 ], a more pronounced shear thinning behaviour, and a higher elasticity compared to linear polypropylene [ 19 , 23 , 33 , 34 ].…”

Preparation and rheology characterization of branched polypropylene during reactive extrusion process

“…Prolonging the life time of macro-radicals and stabilizing them by changing radical intermediate state using styrene and furan derivatives would greatly limit the degradation [14]. Moreover, the addition of PE during the chemical modification of PP can be envisaged as a way of reducing the scission [15]. Iniferter (free radical initiator, transfer agent and terminator) named co-agent is also used to reduce the chain scission and improve grafting reaction.…”