RESUMO
OBJECTIVE: To characterise and compare the tensile characteristics after multi-proportional blending, to determine the proper blending ratio for new thermoplastic material and to compare its mechanical performance with commercial thermoplastics. METHODS: PETG and PC2858 aggregates were blended in five different ratios. Standard specimens of each ratio were molded and tested to determine their mechanical performance. Then the new material with the proper blending ratio was chosen and compared against commercial thermoplastics. RESULTS: With the increase of PC2858 content, the tensile and impact strength increased but elongation at break decreased. When blending ratio (wt %) was 70/30, the PETG/PC2858 exhibited optimal mechanical properties, with a tensile strength of 63.42 ± 1.67 MPa, and a stress relaxation rate of 0.0080 ± 0.0005 N/s, which exceeded those of Erkodur and Biolon. CONCLUSION: By blending PETG and PC2858 at the weight ratio 70/30, we obtained new thermoplastic material which outperformed commercial products.
Assuntos
Materiais Dentários/química , Aparelhos Ortodônticos , Plásticos/química , Cimento de Policarboxilato/química , Polietilenoglicóis/química , Materiais Dentários/síntese química , Elasticidade , Dureza , Humanos , Teste de Materiais , Fenômenos Mecânicos , Membranas Artificiais , Plásticos/síntese química , Polietilenotereftalatos/química , Estresse Mecânico , Propriedades de Superfície , Resistência à TraçãoRESUMO
A mathematical model representing the relation between pulling up speed, time and aspect ratio is reported, accordingly the axially pull-up electrochemical etching method for fabricating nanoprobes is proposed. The tungsten probes with predetermined shape and aspect ratio according to the model were successfully produced with this method. Then the probes were installed inside a micromanipulation system to manipulate the carbon nanotubes and measure their current-voltage (I-V) characteristics. The probe fabrication and application experiments demonstrated the reasonability and reliability of the model and method developed in this note.
Assuntos
Teste de Materiais/instrumentação , Plásticos/química , Estresse Mecânico , Temperatura , ÁguaRESUMO
OBJECTIVE: To compare the mechanical properties of different dental optimal material selection for orthodontic appliance. METHODS: Four commercialized thermoplastic products under different test conditions, and provide the suggestion of thermoplastic products were tested. The tear strength, elongation at break and stress relaxation of these materials were measured under different test conditions. RESULTS: The tear strength declined after thermoforming, and rose again after 2 weeks of distilled water immersion. The elongation at break rose after thermoforming, and declined after 2 weeks of distilled water immersion. No significant changes were observed for brand A under different test conditions. Brand A showed the slowest stress relaxation of 0.0148 N/s. CONCLUSIONS: The mechanical properties of thermoplastic materials were influenced by environmental factors. Brand A exhibited optimal comprehensive properties.
