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This study aimed at evaluating the effects of the incorporation of micro and nanoparticles of CaCO 3 on the properties of poly(vinyl chloride) (PVC), intended to industrial application. The PVC compounds added with particles of different sizes were achieved in an intensive mixer. Rheological, microstructural, mechanical and thermal properties of the compounds obtained were evaluated. The rheology test showed that the compound with the addition of two-particle size plasticized faster compared than other formulations. Microstructural analysis showed a poor particle size distribution for the micro-CaCO 3 charges, and the nano-CaCO 3 samples have agglomerated particles. The thermal analysis showed the compound added with two particle size with higher gelation, and in the loss modulus E' and E", the values also were close. The analyses showed that the combination of the two-particle sizes presented superior results when compared with the micro or nano used singly.

Injection molds can fail after a certain period of use, which may compromise the final part's integrity and quality, but that can be solved using welding repair processes. This work aimed to investigate the influence of AISI P20 molds repaired by Gas Tungsten Arc Welding (GTAW) and Nd-YAG laser-welding processes on the properties of injection-molded parts with semi-crystalline (polypropylene) and amorphous (polycarbonate and acrylonitrile butadiene and styrene terpolymer) thermoplastics. Welds were prepared by machining 0.8 mm-deep 40 mm x 5 mm grooves to be filled by GTAW and Nd-YAG laser-welding deposits, in order to simulate the repair of AISI P20 molds. All polymers were injected into weld-repaired and unrepaired molds, and then evaluated in terms of microstructure, crystallinity degree, mechanical properties and gloss. The results suggest that the repaired region for both studied welding processes, despite the difference in hardness of the weld region, does not significantly affect the properties of semi-crystalline and amorphous injected polymers.

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