CALCIUM STEARATE -TECHNICAL

Ekambaram, Kavitha, and Mohan Doraisamy. Desalination 385 (2016): 24-38.

This study reports the fabrication of hydrophobic nanofiltration membranes by blending calcium stearate with polyvinylidene fluoride (PVDF) through a nonsolvent induced phase inversion process. PVDF was used at 15 wt.% and calcium stearate was incorporated at varying concentrations (0.25-1 wt.%) into dimethyl formamide (DMF) solvent to prepare homogeneous polymer dopes. The mixtures were stirred at 65 °C for 6 hours and degassed at room temperature to eliminate air bubbles. The dope was cast on a glass plate under controlled relative humidity (15% ± 5%), followed by 90 seconds evaporation before immersion into a coagulation bath containing water, 0.2 wt.% sodium lauryl sulfate, and 2 wt.% DMF. Membranes were retained in the bath for 6 hours and stored in 0.1 wt.% formalin solution.
Characterization by FTIR-ATR, XRD, TGA, DSC, FESEM-EDX, SEM, and AFM confirmed the successful incorporation of calcium stearate and demonstrated thermal and mechanical stability. Contact angle and work of adhesion analyses revealed enhanced hydrophobicity, while AFM indicated low surface roughness. The membranes exhibited excellent filtration performance, with molecular weight cut-offs suitable for rejecting inorganic salts in the order Na2SO4 > MgSO4 > MgNO3 > LiCl > NaCl. Antifouling tests using humic acid showed high flux recovery ratios, attributed to the membranes' charge effects, hydrophobicity, and self-cleaning ability.
Calcium stearate effectively modifies PVDF membranes to enhance hydrophobicity, filtration efficiency, and fouling resistance, offering promising applications in water treatment technologies.

Panaitescu, Denis Mihaela, et al. International Journal of Biological Macromolecules 190 (2021): 780-791.

This study explores the application of calcium stearate (CS) as a lubricant and degradation catalyst in the melt processing of poly(3-hydroxybutyrate) (PHB), aiming to improve its processability and biodegradability for sustainable packaging and biomedical uses. PHB-CS compounds were prepared via melt mixing in a Brabender LabStation at 170 °C and 40 rpm. After melting PHB, CS was incorporated at concentrations of 0.05, 0.5, and 5 wt%, followed by 6 minutes of continuous mixing. The resulting molten blends were solidified and compression molded into films (0.8 mm thickness) under 10 MPa pressure at 175 °C.
Calcium stearate's dual functionality derives from its metallic cation, which catalyzes PHB degradation, and hydrophobic anion, enhancing compatibility and processability. Incorporation of CS decreased PHB melt viscosity and molecular weight, reduced melting and crystallization temperatures by up to 5 °C and over 25 °C respectively, and lowered degradation temperature significantly (up to 40 °C reduction at higher loadings). Low CS loading (0.05 wt%) improved mechanical properties and processability, whereas moderate loading (0.5 wt%) enhanced stiffness but reduced tensile strength and accelerated degradation.
This facile melt-mixing approach offers a scalable, environmentally friendly route to tailor PHB thermal and mechanical characteristics by controlling calcium stearate content. The findings provide valuable insights into optimizing biodegradable polymer composites to meet evolving industrial demands for sustainable materials.

Lv, Yajun, et al. Construction and Building Materials 450 (2024): 138684.

Calcium stearate (CS), a hydrophobic agent with low water solubility, has been effectively utilized to enhance the durability of cement-based materials. In this study, low-dosage incorporation of CS was investigated for its ability to improve the waterproofing properties of mortar and mitigate reinforcement corrosion under varying crack widths.
Mortar specimens containing different CS dosages were prepared via a controlled mixing process involving ordinary Portland cement, river sand, superplasticizer, polyethylene fibers, and staged water addition. Mechanical performance, water absorption, hydration products, microstructure, and reinforcement corrosion were systematically evaluated.
Results demonstrated a pronounced improvement in hydrophobicity with increasing CS dosage. At 1.5 % CS, the water contact angle rose to 122.5°, and cumulative water absorption decreased by 78.41 % compared with the control. Although a gradual reduction in compressive and flexural strength was observed with higher CS content, reinforcement mass loss rates remained below 4 %, even in specimens with cracks up to 1 mm wide. When crack widths were ≤ 0.3 mm, CS addition effectively neutralized chloride-induced corrosion, with optimal performance at 1.5 % dosage.
Mechanistically, CS modifies the mortar's pore structure and surface energy, reducing capillary water ingress and ion penetration. This study highlights the potential of calcium stearate as a cost-effective additive for prolonging the service life of reinforced concrete, particularly in environments susceptible to chloride attack.