The molecular weights of the industrial‐grade isotactic polypropylene (i‐PP) homopolymers samples were determined by the melt‐state rheological method and effects of molecular weight and molecular weight distribution on solid and melt state creep properties were investigated in detail. The melt‐state creep test results showed that the creep resistance of the samples increased by Mw due to the increased chain entanglements, while variations in the polydispersity index (PDI) values did not cause a considerable change in the creep strain values. Moreover, the solid‐state creep test results showed that creep strain values increased by Mw and PDI due to the decreasing amount of crystalline structure in the polymer. The results also showed that the amount of crystalline segment was more effective than chain entanglements that were caused by long polymer chains on the creep resistance of the polymers. Modeling the solid‐state viscoelastic structure of the samples by the Burger model revealed that the weight of the viscous strain in the total creep strain increased with Mw and PDI, which meant that the differences in the creep strain values of the samples would be more pronounced at extended periods of time.

This study examined the morphological, rheological, viscoelastic, electrical, and microwave attenuation properties (RADAR absorbent and EMI shielding) of cyclo‐olefin copolymer (COC) composites prepared with the melt mixing method by using different amounts of graphite (0‐75 phr). Rheological percolation threshold of the graphite was determined as ∼38 phr. The RL analyses of the composites showed that the composites containing a moderate filler content (45 phr) exhibited the best radar absorption performance. Absorption bandwidth and minimum reflection loss (RL) value for the sample containing 45 phr of graphite were determined as 2.335 GHz (10.165‐12.5 GHz) and −39.89 dB, respectively. Total shielding effectiveness (SET) values of the sample including 75 phr of graphite varied in the ranges of 30 to 47.5 dB for the sample thicknesses of 7 mm. The correlation of the microstructural parameters and microwave attenuation properties of the composites indicated that the minimum RL value could be obtained at a filler concentration close to the rheological and electrical percolation thresholds. However, it was also revealed that acceptable shielding effectiveness values for commercial applications could be obtained by the samples with higher filler concentrations than the electrical percolation threshold.

Cyclo‐olefin copolymer (COC) composites containing different amounts of nickel (Ni) and/or nickel‐coated carbon (NiC) hybrid fillers were prepared, and their morphological, rheological, mechanical, dielectric, and X‐band microwave absorption properties were examined. Rheological percolation thresholds for Ni and NiC fillers were determined to be in the range of 45 to 60 and 60 to 75 phr, respectively. Both fillers caused no significant increase in melt viscosity at low shear rates. The minimum filler concentrations to obtain acceptable reflection loss (RL) values (RL < −10 dB) were determined as 60 and 45 phr for the Ni and NiC series of samples, respectively. The minimum RL value (RLmin) and the broadest absorption bandwidth were determined as −52.5 dB and 8.2 to 12.5 GHz, respectively, for the composite sample containing 75 phr of Ni, whereas a similar performance could be obtained by the sample containing 45 phr of NiC. Considerable enhancement in the RLmin value could not be provided by the use of hybrid NiC fillers; however, the absorption bandwidth was enlarged, and the minimum sample thicknesses to obtain an acceptable absorption bandwidth were reduced significantly.

In this study, blends of cyclo-olefin copolymers (COC) that had different monomer compositions and poly(Acrylonitrile-Butadiene-Styrene) (ABS) were prepared and variations in their morphological, rheological, and dynamic mechanical properties were investigated. In the morphological analyses, it was seen that all blends with 50/50% composition had a co-continuous morphology, while droplet-matrix morphology was observed for the other compositions. Melt-state shear modulus and viscosity increased with the addition of ABS for the blends prepared with COC derivatives containing 40% and ⁓68% norbornene content by weight, while there was no significant change in the modulus values of those prepared with the COC derivative containing ⁓76% norbornene by weight. On the contrary to other blends, it was observed that the modulus values decreased with the addition of ABS in the blends prepared with COC with 82% norbornene content. Evaluation of the SEM images and Cole-Cole plots indicated that COC-rich blends were more compatible than the ABS-rich blends in the case COC with lower norbornene content was used in polymer blends, while ABS-rich blends became more compatible with increasing norbornene content of COC. K E Y W O R D Scyclo-olefin copolymer (COC), poly(acrylonitrile-butadiene-styrene) (ABS), polymer blend

In this study, different amounts of aluminum dross (Al‐dross) powders were incorporated into polyoxymethylene (POM) by the melt‐mixing method, and morphological, thermal, rheological, mechanical and dielectric properties of the obtained composite samples were investigated. So, it was aimed to develop value‐added products and create an alternative utilization method for industrial waste that poses environmental risk and does not have a useful application area. The morphological analyses performed by scanning electron microscopy (SEM) showed that the Al‐dross contained various inorganic components with different particle sizes such as Al2O3, NaCl. Moreover, no significant structural incompatibility between the POM and Al‐dross was observed. In contrast, the SEM analyses showed non‐coated filler particle surfaces, which were probably due to the breaking of NaCl particles during the extrusion process. In the differential scanning calorimetry (DSC) analysis, it was found that the effect of Al‐dross addition on the crystallization temperature, amount of crystalline structure in the polymer phase or crystallization rate was limited. The rheological analyses showed that the Al‐dross particles formed rheological percolated structures at an Al‐dross ratio of 20% wt. In the dynamic mechanic analysis (DMA), it was observed that the modulus of elasticity (E') increased by approximately 40% and creep strain decreased by approximately 50% by the addition of Al‐dross into the POM phase at the 40% in %wt. Finally, in the dielectric analyses carried out in the frequency range of 1–14 GHz by a vector network analyzer, it was concluded that incorporating Al‐dross at 40% caused an increase of 1.5 and 3 times in real and imaginary part of the complex permittivity.