A unique composite scaffold for bone-tissue engineering applications has been prepared by combining biodegradable poly(lactide-co-glycolide) (PLGA) with bioresorbable calcium phosphate (CaP) cement particles through the process of particle fusion and phase separation/particle leaching. The scaffold is characterized by a highly interconnected macroporosity, with macropores of 0.8-1.8 mm and porosities ranging from 81% to 91%, and improved mechanical properties with respect to the polymer alone, producing excellent dimensional stability. The scaffold properties were controlled by adjusting the processing parameters, including PLGA molar mass and concentration, CaP/PLGA ratio, and porogen size. The differences in mechanical properties between dry, wet/room temperature, and wet/37 degrees C testing conditions, of which the latter are more relevant for materials to be employed in a biological milieu, were investigated. Thus, a scaffold made from PLGA IV 1.13, PLGA concentration 12.5%, and CaP/PLGA ratio 2:1 exhibited significantly different compressive strengths of 0.16 MPa and 0.04 MPa when tested under dry and wet/37 degrees C conditions, respectively. .

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The regeneration of tissues affected by periodontal disease is a complex process; it encompasses the formation of bone, cementum and periodontal ligament. We developed a semi-rigid PLGA (polylactide-co-glycolide acid)/CaP (calcium phosphate) bilayered biomaterial construct to promote periodontal regeneration, which has a continuous outer barrier membrane and an inner topographically complex component. Our experimental model compared periodontal prophylaxis alone with prophylaxis and biomaterial implantation in the treatment of class II furcation defects in dogs. Clinical evaluation, micro-computed tomography, histology and backscattered electron imaging were used for data analysis. Healing occurred uneventfully and bone volumetric values, trabecular number and trabecular thickness were all significantly greater in the treated group; while trabecular separation was significantly greater in the control group. New cementum, bone, and periodontal ligament with Sharpey fibre insertions were only seen in the treated group. Although periodontal regeneration has been reported elsewhere, the advantages of employing our bilayered PLGA + CaP construct are twofold: 1)it did not collapse into the defect; and, 2) its inner side was able to retain the blood clot throughout the buccal defect. The result was greater periodontal regeneration than has previously been reported with traditional flexible membranes.

A new intumescent flame retardant (IFR) system consisting of ammonium polyphosphate (APP) and charing-foaming agent (CFA) and a little organic montmorillonite (OMMT) was used in low-density polyethylene (LLDPE)/ethylene-vinyl acetate (EVA) composite. According to limiting oxygen index (LOI) value and UL-94 rating obtained from this work, the reasonable mass ratio of APP to CFA was 3 : 1, and OMMT could obviously enhance the flame retardancy of the composites. Cone calorimeter (CONE) and thermogravimetric analysis (TGA) were applied to evaluate the burning behavior and thermal stability of IFR-LLDPE/EVA (LLDPE/EVA) composites. The results of cone calorimeter showed that heat release rate peak (HRR-peak) and smoke production rate peak (SPR-peak) and time to ignition (TTI) of IFR-LLDPE/EVA composites decreased clearly compared with the pure blend. TGA data showed that IFR could enhance the thermal stability of the composites at high temperature and effectively increase the char residue. The morphological structures of the composites observed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrated that OMMT could well disperse in the composites without exfoliation, and obviously improve the compatibility of components of IFR in LLDPE/EVA blend. The morphological structures of char layer obtained from Cone indicated that OMMT make the char layer structure be more homogenous and more stable.

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