Biocomposites containing mineral fast-setting cements
Danuta Wala, Genowefa Rosiek Politechnika Wrocławska, Instytut Budownictwa, pl. Grunwaldzki 11, 50-370 Wrocław
Annals 1 No. 2, 2001 pages 184-187
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abstract The results of synthesis of inorganic, fast-setting, biocompatible cements, intended to medical uses, and results of investigations of composites containing this cements are presented in this paper. The exact fitting biocompatible implant to bone is necessary condition of success in surgery repair-bones. Osseous decrease is at last formed during surgical intervention, fitting of shape of fulfilment yet before intervention is difficult. Synthesis cements can used to fixation of implants to bone and can be also used to manufacture of microconcrete containing as fulfilment of grain porous corundum, hydroxyapatite or calcium carbonate. This microconcretes before setting show properties plastic and create large possibilities formations of dimension-fulfilments. Cements realizing above - functions have to be biocompatibility, to show suitable setting time (in moist environment) making possible execution of surgery operating (∼10÷20 min). The setting time cement should be done at pH neutral or weakly alkaline, cements after setting should possess sufficient mechanical strength. Authors of this paper manufactured four cements, which possessed different chemical and mineralogical composition and different hydraulic properties. All investigated cements quickly set in water solution of phosphates (∼10 min). The cement A and B, containing mostly γ-belite, calcium phosphate and wolastonite (CaSiO3) do not show setting property in water. Cement C, which contains active form of belit, shows good hydraulic properties. The compressive strength (Rc), after 28 days of storage of samples in water, was about 50 MPa. Cement D possesses the best hydraulic and mechanical properties. This cement was obtained by burning homogeneous mixture of kaolin (26%), calcium carbonate (49%) and calcium sulfate hemihydrate (25%) at 1270°C. Received cement D (belite-sulfatealuminate) possesses following properties: fast set (20 min), very good workability at little addition of water, quick increase strength in early age, after 1 day Rc = 65 MPa and permanent its increase in long time (peculiarities for samples storing in water), after 90 days Rc = 140.5 MPa, low pH range (9.2÷9.4) in early period of setting, it is non-shrinking cement. The microconcretes containing investigated cements and grains porous corundum or calcium carbonate was manufactured. As additions improving fracture toughness was used a glass fiber or synthetic or coal fiber. In order to improve contact fibre-- matrix addition of amorphous silica was used. Proposed compositions of microconcretes and their mechanical property there are in Table 3. For all investigated composites was obtained very considerable improvement of fracture toughness, high parameters γ F, J075, J5, J10, J20. The property of cements and composites point on possibility of use them in medicine to filling up of osseous decreases, after verification their biocompatibility.