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A novel biocomposites double-layer films using polyhydroxybutyrate (PHB) and cellulose paper were produced. The biocomposites were prepared by the solvent-casting method (with chloroform). Films of the blends were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrograph (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray (XR) and surface roughness measurements. Moisture absorption, water absorption and water vapor permeation of films has been investigated. The PHB impregnated the fibers of cellulose paper and it was on the valley of paper structure. The double-layer films showed diminutions in the moisture absorption, in the water abortion, in water vapor permeation and in surface roughness. According to contact angle, surface free energies and the barrier properties of the films can be considered more hydrophobic. The experimentally observed tensile properties (modulus and tensile strength) of double-layer films with different content of PHB were determined. Measurements show the tensile strength and modulus of cellulose paper increases with the percentage of PHB. SEM photomicrographs of the fractured films surfaces were also analyzed. It was possible to obtain a biodegradable material with little amount of PHB to improve the barrier and the mechanical properties of cellulose paper, taking advantage of the good properties of both materials.

A finite element model of the temporomandibular joint (TMJ) and the human mandible was fabricated to study the effect of abnormal loading, such as awake and asleep bruxism, on the articular disc. A quasilinear viscoelastic model was used to simulate the behaviour of the disc. The viscoelastic nature of this tissue is shown to be an important factor when sustained (awake bruxism) or cyclic loading (sleep bruxism) is simulated. From the comparison of the two types of bruxism, it was seen that sustained clenching is the most detrimental activity for the TMJ disc, producing an overload that could lead to severe damage of this tissue.

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