Electromechanical-Conductive Natural Rubber Doped Eggshell and Eggshell Membrane for Drug Delivery and Actuator Applications

Natural rubber composite materials were prepared by using sulfur curing system of STR 5L added with hen eggshell and eggshell membrane 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 into natural rubber. The main composition of hen eggshells composed of 96.35 wt% calcium carbonate (CaCO3) while mostly composition of hen 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 electrical field response of natural rubber composite materials were measured by moving die rheometer and impedance analyzer, and reported here.

Download Full-text

EMBEDDED PARTICULATE BIOMATERIALS AS DIELECTRIC FILLERS IN ELECTROACTIVE NATURAL RUBBER COMPOSITES

Rubber Chemistry and Technology ◽

10.5254/rct.20.81458 ◽

2019 ◽

pp. 000-000

Author(s):

Poramin Bunprasert ◽

Nuchnapa Tangboriboon

Keyword(s):

Natural Rubber ◽

Electrostatic Interactions ◽

Eggshell Membrane ◽

Additional Stress ◽

Large Strains ◽

Rubber Composites ◽

Electrical Field ◽

Additional Advantage ◽

Natural Rubber Composites ◽

Eggshell Waste

ABSTRACT Both eggshell and eggshell membrane are potential alternative dielectric biomaterials because of their inorganic and organic matter contents, respectively. Adding eggshell or eggshell membrane into natural rubber compounds made using the sulfur curing system has many advantages such as flexibility, ease of formation, ability to operate under large strains and shape conformability, lightweight, and low cost of production. The results indicated that the natural rubber composite had a rubberlike characteristic and good elasticity. Both the eggshell and eggshell membrane acted as a dispersed-phase or dielectric filler that can absorb and store additional stress effects, resulting in fast curing and increasing crosslink density. Under a variable electrical field, eggshell and eggshell membrane particles induced dipolar moments and led to interparticle interactions that increased the storage modulus response substantially by nearly two orders of magnitude at 1.5 kV/mm. The obtained natural rubber composites can contribute toward more effective polarization and hence stronger electrostatic interactions between the embedded particles, resulting in a fast deflection response due to the dielectrophoresis force generation at low electrical field strengths of 300 and 350 V/mm for eggshell and eggshell membrane, respectively. The additional advantage of eggshell waste utilization is welcome as a means of reducing global climate warming and adding value to eggshell waste.

Download Full-text

Effect of carbon allotropes on foam formation, cure characteristics, mechanical and thermal properties of NRF/carbon composites

Journal of Cellular Plastics ◽

10.1177/0021955x20979548 ◽

2020 ◽

pp. 0021955X2097954

Author(s):

Pollawat Charoeythornkhajhornchai ◽

Wutthinun Khamloet ◽

Pattharawun Nungjumnong

Keyword(s):

Natural Rubber ◽

Bubble Diameter ◽

Carbon Composites ◽

Mechanical And Thermal Properties ◽

Foam Formation ◽

Carbon Filler ◽

Composite Foam ◽

Carbon Allotropes ◽

Blowing Agent ◽

Rubber Composite

Natural rubber composite foam with carbon such as carbon black (CB), carbon synthesized from durian bark (CDB), graphite (GPT), graphene oxide (GO), graphene (GPE) and multi-walled carbon nanotubes (MWCNT) was studied in this work to investigate the relationship between foam formation during decomposition of chemical blowing agent mechanism and crosslink reaction of rubber molecules by sulphur. Natural rubber composite foam with carbon particle was set at 3 parts per hundred of rubber (phr) to observe the effect of carbon allotropes on foam formation with different microstructure and properties of natural rubber composite foam. The balancing of crosslink reaction by sulphur molecules during foam formation by the decomposition of chemical blowing agent affects the different morphology of natural rubber foam/carbon composites leading to the different mechanical and thermal properties. The result showed the fastest cure characteristics of natural rubber foam with 3 phr of graphene (NRF-GPE3) which was completely cure within 6.55 minutes (tc90) measured by moving die rheometer resulting in the smallest bubble diameter among other formulas. Moreover, natural rubber foam with 3 phr of MWCNT (NRF-MWCNT3) had the highest modulus (0.0035 ± 0.0005 N/m2) due to the small bubble size with high bulk density. In addition, natural rubber foam with 3 phr of GPT (NRF-GPT3) had the highest thermal expansion coefficient (282.12 ± 69 ppm/K) due to high amount of gas bubbles inside natural rubber foam matrix and natural rubber foam with 3 phr of GO (NRF-GO3) displayed the lowest thermal conductivity (0.0798 ± 0.0003 W/m.K) which was lower value than natural rubber foam without carbon filler (NRF). This might be caused by the effect of bubble diameter and bulk density as well as the defect on surface of graphene oxide compared to others carbon filler.

Download Full-text