RESUMO
The growing demand in the consumer market for products with sustainable technologies has motivated new applications using overmolded natural fiber composites. Therefore, studies have been conducted mainly to understand the adhesive properties of overmolded parts. In the present study, a polypropylene (PP) composite with 30% coconut fibers without additives was developed with the aid of a corotating twin screw extruder. Subsequently, a multicomponent injection mold was developed based on the geometry of the ISO 527 type I specimen, in which samples overmolded with PP and PP-coconut-fiber composite, with the overlap in the central area, were obtained to evaluate the adhesive strength of dissimilar materials. The objective of this study was to evaluate the bond between PP and PP-coconut-fiber composite under different processing conditions using an adhesive strength testing device to perform a pure shear analysis. The experimental conditions followed a statistical design considering four factors in two levels and a significance level of 5%. The results indicated that adhesive strength increased significantly as the overlap area increased. It was observed that temperature and injection flow rate were the factors that most contributed to strengthening the bonds of dissimilar materials.
RESUMO
Nos últimos anos, os biomodelos de prototipagem rápida vêm ganhando mais espaço na Odontologia, sobretudo, nas especialidades de Cirurgia e Traumatologia Bucomaxilofacial e Implantodontia. Suas vantagens incluem planejamento mais preciso, diminuição do tempo cirúrgico, consequentemente, também do tempo de anestesia e melhores resultados funcionais e estéticos. Este estudo teve como objetivo comparar medidas lineares obtidas de imagens tridimensionais virtuais (construídas no programa 3D Doctor, a partir de exames de tomografia computadorizada de pacientes portadores de neoplasias odontogênicas nos maxilares) e de seus respectivos biomodelos, obtidos pela técnica de impressão tridimensional. As medidas virtuais foram feitas com a ferramenta régua disponível no próprio programa e as medidas nos biomodelos foram feitas com um paquímetro eletrônico digital, por dois avaliadores e repetidas após uma semana. As médias entre as medidas obtidas foram testadas quanto à distribuição normal pelo teste de Kolmogorov e Smirnov e, posteriormente, foi aplicado o teste t Student para amostras pareadas, com uma probabilidade de erro de 5%. A variabilidade interexaminador foi avaliada pelo coeficiente de Lin. Os resultados demonstraram que não houve diferença estatística (p > 0,05) entre as medidas das imagens virtuais e dos seus respectivos biomodelos, além de uma forte correlação entre os avaliadores tanto para as medidas virtuais (0,9975), quanto para as medidas nos biomodelos (0,9972).
In recent years, rapid biomodel prototyping has been gaining more evidence in Dentistry, particularly on surgical and implantodontic areas. Its advantages include more accuracy on treatment planning, decreased surgical and anesthesia times with better functional and aesthetic results. This study aimed to compare linear measurements (obtained from three-dimensional virtual images, built into the 3-D Doctor software, from computed tomography scans of four patients referred for surgery) and their respective biomodels, obtained by three-dimensional printing technique. The virtual measurements were made with a rule available in the program itself and the measures in the mandible models were made with a digital caliper by two examiners and repeated one week later. Measurement values were tested for normal distribution by Kolmogorov-Smirnov test. The Student´s t-test for paired samples (5% level of significance) was used for comparisons. The inter-examiner variability was assessed by the coefficient of Lin. The results showed no statistical difference (p > 0.05) between measures of virtual images and their respective biomodels, with a strong correlation between examiners for both virtual (0.9975) and biomodels (0.9972) measurements.