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This research introduces an analysis of the anisotropic electrical resistivity (ER) and its relation to the electromagnetic shielding effectiveness (EMSE) for two injection‐molded carbon‐fiber‐reinforced polybutylene terephthalates (PBTs). The properties were measured for 2‐mm thick injection moldings considering the effect of melt temperature, injection velocity, and flow distance. The results for one compound showed an EMSE in the range of 30–40 dB, while EMSE for a compound with lower filler content is in the range of 45–75 dB. A combination of higher temperature and higher velocity leads to an increase of EMSE for both compounds in the range of 3%–8.5%. However, the increase in flow path reduced the EMSE for both compounds up to 10%. A novel experimental apparatus was used to measure the anisotropic ER in the three directions, that is, parallel, perpendicular, and transversal to flow. It is evident that injection molding induced high anisotropy for both compound specimens, and, depending on the processing conditions, produced similar longitudinal resistivity (0.2–4 Ω.cm) but higher transversal resistivity (8–22 Ω.cm). ER properties were compared with EMSE, evidencing an inverse relation as expected. Furthermore, it was found that the longitudinal resistivity is the main contributor to the specimens shielding.

This study addresses the characterization of nano and hybrid poly(ethylene terephthalate) (PET)-based composites obtained by injection molding process. The aim is to demonstrate the effect of adding various nanoclay amounts on the morphology and mechanical behavior of unreinforced and glass fiber (GF) reinforced PET matrices. Also, it addresses the possibility of preserving the mechanical response of the composites while decreasing the amount of GF. Nanocomposites were prepared by adding 0.5, 1.0, 3.0, and 5.0 wt% of montmorillonite to the unreinforced PET matrix; hybrid composites were also prepared by adding the aforementioned nanoclay amounts to the 20% GF reinforced PET (PET20). A 35% GF reinforced PET was used as a reference material for the mechanical properties comparison. X-ray diffraction and transmission electron microscopy studies revealed that the characteristic (001) peak of the nanocomposite obtained by extrusion shifted to the lower angle region stating an intercalated structure. The subsequent injection molding process altered the morphological structure of the composites, reducing the basal distance for small loadings of nanoclays. Differential scanning calorimetry showed that the addition of nanoclay increases the degree of crystallinity and decreases the cold crystallization temperature of both PET systems. Full exfoliation of the nanoclay was not attained but the nanoparticles dispersion in combination with their intercalated morphology improved the mechanical properties of PET composites optimally for 1% of incorporation. The envisaged mechanical properties of PET20 were improved (initial modulus ↑22%, stress at yield ↑14%, and strain at break ↑4%) for the aforementioned optimal value of incorporation. C

This work focused on the study of the impact event on molded parts in the framework of automotive components. The influence of the impact conditions and processing parameters on the mechanical behavior of talc-filled polypropylene specimens was analyzed. The specimens were lateral-gate discs produced by injection molding, and the mechanical characterization was performed through instrumented falling weight impact tests concomitantly assisted with high-speed videography. Results analyzed using the analysis of variance (ANOVA) method have shown that from the considered parameters, only the dart diameter and test temperature have significant influence on the falling weight impact properties. Higher dart diameter leads to higher peak force and peak energy results. Conversely, higher levels of test temperatures lead to lower values of peak force and peak energy. By means of high-speed videography, a more brittle fracture was observed for experiments with higher levels of test velocity and dart diameter and lower levels of test temperature. The injection-molding process conditions assessed in this study have an influence on the impact response of moldings, mainly on the deformation capabilities of the moldings.

This work presents an investigation of the properties of poly(ethylene terephthalate)/glass fibers/nanoclay multiscale composites. The aim is to demonstrate the effect of adding various clay amounts on the morphology and mechanical performances of multiscale PET composites. Multiscale composites were prepared by adding 0.5, 1.0, 3.0, and 5.0 wt% of Cloisite 15A montmorrillonite. Initially, a masterbatch of pure PET blended with 10 wt% of Cloisite 15A was obtained in a co-rotating twin screw extruder. The multiscale composites were then blended via mechanical mixing, and injection moulded by adding the masterbatch to the glass fibre reinforced matrix. The morphological and mechanical characterizations of all compounds are discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the characteristic (001) peak of the nanocomposite obtained by extrusion (masterbatch) shifted to the lower angle region stating an intercalated structure. However, the subsequent injection moulding process changed the morphological structure of the multiscale nanocomposites reducing the basal distance mostly for small loadings of nanoclay. The addition of nanoclay to PET matrices increases the degree of crystallinity, the clay platelets possibly playing the role of nucleating agent, as revealed by DSC and FTIR. The time relaxation spectra broaden as seen by DMA, as the ratio of clay/polymer interfaces increases. The yield stress of composites with 0.5 and 1 wt% of C15A content are enhanced. For more than 3% of nanoclay, the yield stress decreases. The Young's modulus is increased when adding nanoclay. Indeed, clay exfoliation was not attained, but the intercalated particle dispersion improved the stiffness properties of PET/glass fibers/nanoclay composites.