Electromechanical-conductive natural rubber doped eggshell and eggshell membrane for drug delivery and actuator applications

Natural rubber composite materials were prepared from vulcanization STR 5L in sulfur curing system by being added with eggshell and eggshell membrane in order to increase electrical and mechanical properties for biomimetic actuator and artificial muscle applications. Samples were vulcanized at temperature 150°C. Hen eggshells and eggshell membrane powder (0, 20, 40, and 60 phr) were added in natural rubber. The main composition of eggshells is calcium carbonate (CaCO3) of high purity more than 96.35 wt% whereas the main composition of eggshell membrane is fibrous protein in terms of collagen. The best condition is addition of eggshell 40 phr (formula 3) and eggshell membrane 20 phr (formula 5) to obtain the highest storage modulus response equal to 2.85 x 106 and 2.97 x106 Pa, respectively. The curing time (Tc90) of pure natural rubber (formula 1), formula 3, and formula 5 are 8.22, 6.73, and 5.67 min, respectively. Furthermore, the curing time, rheology, and electric field response of natural rubber composite materials are investigate by moving die rheometer and compression set, and the results are reported here.Keywords: Composites; Eggshell; Eggshell membrane; Electroactive elastomer; Actuato

Effects of Foaming Agents and Calcium Carbonate on Thermo-Mechanical Properties of Natural Rubber Foams

Pjene od prirodnog kaučuka pripremljene su umreživanjem prirodnog kaučuka u sustavu sumpornog umreživanja pri 396 K s pomoću dvovaljčanog mlina s pjenilima: natrijev bikarbonatom (NaHCO3) ili N, N´-dinitrosopentametilen tetraminom (DNPT, C5H10N6O2), te s 0, 20, 40 i 60 phr kalcijeva karbonata (CaCO3) kao punilom. Dobivene pjene od prirodnog kaučuka su lagane, dobrih toplinskih i mehaničkih svojstava, prikladne za toplinsku izolaciju, apsorpciju energije i strukturne uporabe. Oba pjenila dodana u smjesu s prirodnim kaučukom, NaHCO3 i DNPT, razgradila su se i oslobodila plinove pri temperaturi umreživanja (umreživalištu) od 396 K, kako bi se stvorile otvorene i zatvorene stanične strukture. Dodavanje 60 phr CaCO3 čestica punila u pjene prirodnog kaučuka poboljšalo je mehanička i toplinska svojstva kako su ionski naboji Ca2+ i CO 3+ 2- proizveli veze među atomima unutar matrice pjene prirodnog kaučuka. Dobivena pjena od prirodnog kaučuka s punilom 60 phr CaCO3 i s NaHCO3 imala je nasipnu gustoću od 240,5 kg/m3, zaostalu pritisnu deformaciju od 32,60 % i toplinsku provodnost od 0,066 W/mK. Dobivena pjena od prirodnog kaučuka s punilom 60 phr CaCO3 i s DNPT imala je nasipnu gustoću od 219,0 kg/m3, zaostalu pritisnu deformaciju od 11,30 % i toplinsku provodnost od 0,070 W/mK, pri temperaturama iznad 800 °C.Natural rubber foams were prepared from the vulcanization of natural rubber in a sulfur curing system at 396 K by a two roll mill with foaming agents; sodium bicarbonate (NaHCO3) or N, N´-dinitrosopentamethylene tetramine (DNPT, C5H10N6O2), and with 0, 20, 40, and 60 phr calcium carbonate (CaCO3) as a fi ller. The obtained natural rubber foams are lightweight, with good thermal and mechanical properties, suitable for thermal insulation, energy absorption, and structural uses. Both foaming agents added in the natural rubber, namely NaHCO3 and DNPT, decomposed and released gases at the vulcanization temperature of 396 K to produce open and closed cell structures. Adding of 60 phr CaCO3 fi ller particles into the natural rubber foams enhanced the mechanical and thermal properties as the ionic charges Ca2+ and CO3+ 2- produced the interatomic bondings within the natural rubber foam matrix. The obtained natural rubber foam with the 60 phr CaCO3 fi ller and with NaHCO3 possessed the bulk density, compression set, and thermal conductivity of 240.5 kg/m3, 32.60%, and 0.066 W/mK, respectively. The obtained natural rubber foam with the 60 phr CaCO3 fi ller and with DNPT possessed the bulk density, compression set, and thermal conductivity of 219.0 kg/m3, 11.30%, and 0.070 W/mK, respectively, temperatures above 800°C

Lead zirconate (PbZrO3) embedded in natural rubber as electroactive elastomer composites

Perovskite lead zirconate (PbZrO3) was synthesized in an orthorhombic form at a temperature below the Curie temperature, TC. The orthorhombic form is a noncentrosymmetric structure which is capable of spontaneous polarization. Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns confirm the successful synthesis of the lead zirconate; and scanning electron microscopy (SEM) micrographs indicate that PbZrO3 particles are moderately dispersed in the natural rubber (NR) matrix. Without an electrical field, the particles merely act as a ferroelectric filler, which can absorb and store additional stress. Under an electrical field, particle-induced dipole moments are generated, leading to interparticle interaction and a substantial increase in the storage modulus. At a small amount of lead zirconate particulates present in the natural rubber matrix, at a volume fraction of 0.007306, the electrical conductivity increases dramatically by nearly two orders of magnitude at the electrical frequency of 500 kHz

Innovation of Embedding Eggshell to Enhance Physical-Mechanical-Thermal Properties in Fired Clay Bricks via Extrusion Process

Eggshell functioned as a bio-filler and sintering aid added into earthenware clay compounds to make fire clay bricks via extrusion process. The main composition of eggshell is calcium carbonate (CaCO3) while the main composition of earthenware is aluminosilcate (Al2O3.2SiO2.2H2O) and other oxide compounds. Calcium carbonate in eggshell can react to chemical substances in earthenware clay compound to form calcium alumnosilicate or anorthite and wollastonite or calcium silicate phase formation of the fired clay bricks. Adding 20%wt eggshell powder into clay bricks and fired at 1000°C for 5 hrs., affects to the physical-mechanical-thermal properties, i.e. high compressive strength and hardness, good thermal expansion coefficient, good true density, and low water absorption. In general, the theoretical compressive strength, hardness, and water absorption of desired refractory are more than 7.0 MPa, 6.0 HV, and less than 25%wt, respectively. Therefore, the obtained fired clay bricks added eggshell powder and fired at 1000°C for 5 hrs., are potential for use as bricks for construction and thermal insulation

Innovation of Embedding Eggshell to Enhance Physical-Mechanical-Thermal Properties in Fired Clay Bricks via Extrusion Process

Eggshell functioned as a bio-filler and sintering aid added into earthenware clay compounds to make fire clay bricks via extrusion process. The main composition of eggshell is calcium carbonate (CaCO3) while the main composition of earthenware is aluminosilcate (Al2O3.2SiO2.2H2O) and other oxide compounds. Calcium carbonate in eggshell can react to chemical substances in earthenware clay compound to form calcium alumnosilicate or anorthite and wollastonite or calcium silicate phase formation of the fired clay bricks. Adding 20%wt eggshell powder into clay bricks and fired at 1000°C for 5 hrs., affects to the physical-mechanical-thermal properties, i.e. high compressive strength and hardness, good thermal expansion coefficient, good true density, and low water absorption. In general, the theoretical compressive strength, hardness, and water absorption of desired refractory are more than 7.0 MPa, 6.0 HV, and less than 25%wt, respectively. Therefore, the obtained fired clay bricks added eggshell powder and fired at 1000°C for 5 hrs., are potential for use as bricks for construction and thermal insulation