Addition Of Superabsorbent Polymer Research Articles

Design and control shrinkage behavior of high-strength self-consolidating concrete using shrinkage-reducing admixture and super-absorbent polymer

In the present study, self-consolidating concrete (SCC) with 28 days compressive strength of 110 MPa was fabricated. Its workability, hydration heat evolution, chloride penetration resistance, and mechanical properties were analyzed. To enhance its volume stability, shrinkage-reducing admixture (SRA) and super-absorbent polymer (SAP) were used, and their effect on autogenous shrinkage, drying shrinkage, and strength of the concrete were evaluated. The results indicate that high-strength SCC can be achieved using a carefully designed ternary binder system (made with cement, fly ash, and silica fume), water-reducing admixture, and low water-to-binder ratio (W/B = 0.20). Addition of SRA and SAP into the concrete significantly reduced autogenous shrinkage and slightly reduced drying shrinkage. SAP is more effective in reducing autogenous shrinkage at later age, and the effect of SRA is better than that of SAP for drying shrinkage reduction.

Influence of super absorbent polymer on soil water retention, seed germination and plant survivals for rocky slopes eco-engineering

To improve the utilization of water resources on rocky slopes eco-engineering, super absorbent polymer (SAP) with the function of water retention was applied. Super absorbent polymer in three levels, 0.15%, 0.3% and 0.45% were mixed with sandy loam soil. This study was aimed to evaluate the saturated water content, evaporation rate and water holding capability of SAP treated soils, determine seed germination rate and plant survivals in soil with SAP by absorbing and spraying experiments. The addition of SAP to the sandy loam soil resulted in a significant increase of the soil water retention compared to the controls. Also, the seed germination was significantly higher in SAP amended soil than in the soil without SAP, survival times of grass and woody were prolonged under water stress. 0.30% SAP treatment was the optimum selection for sandy loam soil improvement on steep rocky slopes. These studies indicated that SAP with good water retention properties, was very effective in enhancing water uptake and utilization of water for plants growth, and could be expected to have wide potential applications in rocky slopes eco-engineering.

Effects of super-absorbent polymer on dry matter accumulation and nutrient uptake of Pinus pinaster container seedlings

Super-absorbent polymer (SAP) is a widely studied cross-linked hydrophilic polymer used as water absorbent material. However, little information is available concerning the effects of SAPs on the growth and nutrient accumulation in forest container seedlings. The present study was conducted to quantify the effects of SAP applied with or without fertilizer on the dry matter and nutrient uptake of Pinus pinaster container seedlings. SAP addition with fertilizer increased dry matter along with increased seedling emergence time. However, no effect was found without fertilizer. Compared with fertilizer only, rapid accumulation time of nitrogen (N) and potassium (K) was 7 days longer resulting from SAP addition. The maximum daily N and K accumulations in the fertilized seedlings increased by 9.31 and 10.44 %, respectively, whereas those of the unfertilized seedlings did not differ significantly. SAP addition had little effect on phosphorous (P) uptake, except for an increase in the maximum daily P accumulation under fertilized conditions. The shoot and root of P. pinaster with SAP had 8.61 and 13.70 % higher yields, respectively, than those that received fertilizer only. Compared with fertilizer only, SAP addition with fertilizer increased the N and K contents by 7.15 and 10.04 %, respectively, whereas the P content did not differ significantly. Under fertilized conditions, N, P, and K uptake increased by 17.17, 10.13, and 20.33 %, respectively, from SAP addition. Hence, SAP could be used as a nutrient absorption enhancer (mainly N and K) in forest container seedlings, aside from being a water absorbent material.

Controlling the coefficient of thermal expansion of cementitious materials – A new application for superabsorbent polymers

Abstract Self-desiccation occurring in low w/c cement paste leads not only to autogenous shrinkage, but also causes an increase of the coefficient of thermal expansion (CTE) at early ages. This increase can reach about 70% or even more in the first days of hydration. The latter effect is due to the internal relative humidity (RH) changes induced by temperature changes, which cause additional deformation acting in the same direction as the pure thermal dilation in a partially saturated cementitious material. Internal curing by means of superabsorbent polymers (SAP) has recently been proven effective for promoting hydration of cement and for limiting self-desiccation and autogenous shrinkage. This study shows that SAP are also able to control or even completely eliminate another negative effect of self-desiccation, the increase of the CTE. This is to the authors’ knowledge the first such application of SAP. In this work, both aspects of SAP use are investigated, with special focus on limiting the thermal expansion coefficient. First, self-desiccation and self-desiccation shrinkage and their reduction with SAP are investigated in cement pastes and mortars using water-activity measurements and linear shrinkage measurements with corrugated tubes. Next, the thermal expansion is studied experimentally using both volumetric and linear methods for a series of cement pastes and mortars of different w/c. Addition of SAP in cement pastes and mortars is proven to practically eliminate the increase of the CTE during the first days of hardening, limiting the CTE to only 60–70% of the value developed for materials without SAP addition. The reduction of the CTE is possible thanks to maintaining high internal RH levels and consequently reducing the temperature effect on RH.

고흡수성 수지를 이용한 흡수성 실리콘의 특성 연구

실리콘 수지는 소수성이 강한 고분자이기 때문에 수분을 흡수하는 기능이 전혀 없다. 하지만 고흡수성 수지(Super Absorbent Polymer)를 첨가제로 사용하면 기존의 실리콘보다 월등한 흡수성을 갖게 된다. 본 연구에서는 무정형 형태의 입자 크기가 다른 아크릴계 고흡수성 수지 3가지를 선택하여 배합비를 설정하고 2액형 타입의 의료용 실리콘 소재에 적용해서 수분을 흡수하는 기능을 갖는 새로운 실리콘 소재를 개발하였다. 고흡수성 수지의 첨가에 의한 실리콘 수지의 제조시 입자 사이즈와 함량을 달리하면서 인장, 인열, 압축, 경도에 대한 기계적 물성 변화를 알아보았으며, 시간에 따른 실리콘 수지의 흡수성을 측정하였다. 또한 전자 현미경을 통해 고흡수성 수지의 입자형태와 실리콘 수지와의 분포도를 관찰하였다. Silicone resin has no water-absorbing function because it is a strong hydrophobic polymer. However, addition of super absorbent polymer gives much better absorbency than that of conventional silicone resin. In this study, we developed novel silicone materials with water-absorbing function by choosing three types of amorphous acrylic super absorbent polymers with different particle sizes, determining the mixing ratio of the three polymers and applying the mixtures into two-component type silicone material for medical purpose. The change in the mechanical properties such as tensile strength, tear strength, compressive strength and hardness was investigated by varying the particle size and content ratio of the added super absorbent polymers while preparing the silicone resins. The absorbency of the silicone resins was measured over time. Additionally, the particle shape of the super absorbent polymers as well as the distribution within the silicone resin was observed using an optical microscope.

Influence of additives on the thermal behavior of nickel/metal hydride battery

This study discusses the thermal behavior of the 6.5 Ah cylinder Ni/MH hydride battery with 0.5 wt% ytterbium oxide (Yb2O3) in nickel electrode and 1.0 wt% super absorbent polymer (SAP) in hydrogen-storage alloy (MH) electrode during charging to 150% of its rating capacity. Quantity of heat and heat generation rate of the battery during charging are studied by quartz frequency microcalorimeter. Heat generation curve is fitted into a function, and heat transport equation is solved. Using measured data, the internal temperature profiles at the terminal moment of charging at 1C, 3C, and 5C are simulated by FEM. Influence of Yb2O3 and SAP on the thermal behavior of Ni/MH battery is examined by the two-dimensional thermal model. Results show that addition of Yb2O3 and SAP can achieve substantial improvement for thermal behavior of Ni/MH battery at 1C,3C, and 5C charging.