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Use of fiber reinforced composites derived from renewable sources has increased in recent years, aiming at a balance between sustainability and technological development. This research sought to develop poly (lactic acid) (PLA)/poly (ε-caprolactone) (PCL) composites using wood powder (WP) as reinforcement. The composites were initially prepared in a co‐rotational twin‐screw extruder, and the extruded granules were then molded by injection. Mechanical properties (impact, traction, Shore D hardness), heat deflection temperature (HDT), differential scanning calorimetry, contact angle, and analysis with scanning electron microscopy were evaluated. ANSYS® computer simulation for mechanical performance of the materials was used to assess the performance of disposable cups. Impact strength for PLA/PCL bioblend and PLA/PCL/WP composites was higher than neat PLA. In addition, Shore D hardness, elongation at break, and HDT were on the same level as PLA, indicating that high WP concentrations did not severely compromise these properties. However, losses were observed in elastic modulus and tensile strength, and the PLA/PCL/WP composites increased the interaction with water, as reflected in the contact angle. From a practical standpoint, and as verified in the simulation, mechanical performance of the composites was satisfactory for the manufacture of disposable cups. The results are valuable for the area of recycling since it is possible to reuse and add value to a discarded material, thereby reducing costs and promoting sustainability.

O resíduo vulcanizado de estireno-butadieno (SBRr) proveniente da indústria de calçados foi reaproveitado como modificador de impacto de compostos à base de poliamida 6 (PA6). O copolímero SEBS-MA e a argila montmorilonita foram incorporados como aditivos de compatibilização e reforço, respectivamente. Os compostos foram processados em um misturador interno e moldados por injeção. As propriedades de reometria de torque, resistência ao impacto, resistência à tração, temperatura de deflexão térmica (HDT) e microscopia eletrônica de varredura (MEV) foram avaliadas. O torque dos compostos aumentou em relação à PA6, especialmente quando 10% do SEBS-MA foi incorporado em PA6/SBRr, possivelmente devido ao maior nível de interação entre os componentes. A mistura PA6/SBRr/SEBS-MA apresentou valores expressivos na resistência ao impacto (124,2 J/m) e alongamento na ruptura (> 140%), com manutenção da HDT no mesmo nível da matriz de PA6. A morfologia obtida por MEV comprovou uma boa adesão interfacial e refinamento da fase dispersa, confirmando as boas propriedades mecânicas. Ao adicionar argila montmorilonita no sistema PA6/SBRr/SEBS-MA, o efeito mais proeminente foi para obtenção de alta HDT e, ao mesmo tempo, recuperação no módulo elástico e resistência à tração. Porém, houve deterioração da resistência ao impacto e alongamento na ruptura. Os resultados indicam potencial para o reaproveitamento do SBRr, visando a produção de compostos PA6/SBRr/SEBS-MA e PA6/SBRr/SEBS-MA/argila com propriedades sob medidas para aplicações específicas.

To analyze the effect of intra-oral application of CPP-ACP and CPP-ACPF pastes on the surface hardness of initial dental erosion lesions.Bovine enamel specimens were randomly assigned into 6 volunteers in 3 treatment groups: GI: CPP-ACP paste, GII: CPP-ACPF paste and GIII (Control): Placebo paste without CPP-ACP and without fluoride. Enamel specimens were selected by surface hardness (SHi), in vitro eroded by immersion in hydrochloric acid for 30 seconds (SHdes) and randomized between treatment groups and volunteers, who used the palatal intraoral device for 2 hours, applied the treatment on the specimens and used the palatal intraoral device for an additional 3 hours in 3 crossed phases, interspersed with a 7-day washout period. Subsequently, the surface hardness (SHre) was measured to estimate the re-hardening potential of the softened enamel promoted by treatments. Data were analyzed using the t-test and one-way ANOVA, adopting 5% significance level. Mean final and post-erosion hardness values were statistically significant for pastes tested (p<0.05), which presented re-hardening effect of the softened enamel, but with no difference between them and placebo (p>0.05). CPP-ACP and CPP-ACPF pastes did not demonstrate higher efficacy in re-hardening the eroded enamel compared to placebo paste.

This work investigated the effect of thermo-oxidation aging in blends of copolymer polypropylene (PPc)/recycled copolymer polypropylene (PPcr) from industrial container waste, coded as PPc/PPcr blends. All compounds were melt extruded, and the injection molded specimens were characterized by mechanical properties (tensile and impact), Fourier-transform infrared spectroscopy (FTIR), melt flow index (MFI), contact angle, heat deflection temperature (HDT), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). FTIR spectra presented bands related to the hydroperoxides and carbonyl groups, as resulted from thermo-oxidation aging. The contact angle decreased upon a thermo-oxidation aging influence, corroborating the FTIR spectra. PPcr presented higher MFI as a consequence of reprocessing. Impact strength and elongation at break were quite sensible to the thermo-oxidation aging influence and were progressively reduced upon increased time, whereas tensile strength, elastic modulus, and HDT only slightly changed. SEM images of PPc presented a higher quantity of pulled-out particles, resulted from a lower interaction between phases, i.e., polypropylene and ethylene/propylene. From the impact strength and toughness data, proper dissipation energy mechanisms were found in PPc/PPcr blends. Summing up, using PPcr contributed to minimize properties’ losses, which may be related to the stabilizer agents, whereas the described results presented great potential for the PP market, while contributing to the sustainable environment.

The residue of coconut flour (RCF) was used as a bioadditive to evaluate its technological potential as an accelerator of polycaprolactone (PCL) biodegradation. PCL/RCF biocomposites (5-30% by weight) were processed using an internal mixer, and further on, specimens were molded by compression and injection. Experiments such as contact angle, torque rheometry, impact strength, tensile strength, Shore D hardness, thermogravimetry (TG), optical microscopy (OM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were applied to evaluate the biocomposites’ performance. Increasing RCF content into PCL reduced the contact angle, suggesting biocomposites with greater wettability. As a consequence, favoring microorganisms’ proliferation in the biocomposites, providing a higher biodegradation rate as observed by OM. Neat PCL showed weight loss of 8.1% after 60 days of biodegradation while adding 5% RCF increased this parameter to 13.2%. Severe biodegradation was verified in PCL/RCF (30%) since 41% of weight loss was verified. Torque rheometry indicated that up to 10% RCF in the PCL matrix did not compromise processability and maintained good mechanical properties. From OM and visual analysis, microorganisms’ proliferation on the specimens’ surfaces was observed, providing severe deterioration and erosion, corroborated by the high weight loss. FTIR spectra displayed reduced band intensity of ester and methylene groups of PCL and PCL/RCF, along with the biodegradation and appearance of hydroxyl bands. The crystallinity evaluated from XRD increased for a longer biodegradation time, suggesting consumption of the amorphous PCL. In general, coconut flour is a valuable raw material to accelerate PCL biodegradation, indicating potential as an ecological bioadditive and pro-degradant.