Effect of pre-mastication on dispersion of nanoclay in presence of carbon black in an inner liner compound: Studies on physicomechanical and functional properties

The present study demonstrates the use of “pre-mastication” technique for getting higher dispersion of organoclay, Cloisite 15A, in an inner liner compound based on 70:30 bromobutyl and natural rubber blend, in presence of higher concentration of carbon black (60 phr) for the improvement of functional properties like fatigue cut growth and air permeability resistance. Studies have showed that the organoclay was almost equally distributed within the blend both in absence as well as in presence of carbon black. The vulcanization curve showed a marked increase in cure acceleration as well as a significant rise in the maximum torque value because of higher crosslinking aided by the participation of the quaternary amine present in Cloisite 15A; however, in the carbon black loaded compound, the cure acceleration was not so pronounced because of engaging interaction between amine and functional groups of carbon black. The microscopic study revealed a good dispersion of Cloisite 15A within the elastomer blend- in presence of carbon black. The anisotropic platelets of Cloisite 15A and carbon black particles jointly formed “nano units”, which occluded a portion of elastomer segments vis-a-vis partial intercalation within the clay gallery. Such a reinforcing model was instrumental in improving the physicomechanical and functional properties under static and dynamic conditions. The organoclay displayed a much-improved properties at 2 and 4 phr doses in presence of 60 phr carbon black because of formation of enough “nano units” while deterioration was observed at 6 phr dose due to clay aggregation. Based on the results obtained on functional properties it was concluded that the 4 phr of organoclay compounded in “pre-mastication” mode delivered the best improvement and thus it was recommended for future up-scaling study.     

Coupling effect of non-relaxing and high temperature on fatigue properties of carbon-black filled isoprene rubber

This paper presents an extensive experimental investigation on fatigue properties of carbon-black filled isoprene rubber under complex loadings. A basic life prediction model taking strain energy density as fatigue parameter is first proposed based on fatigue crack growth tests and uniaxial tension fatigue tests under relaxing loads at room temperature. A database of fatigue life including relaxing and non-relaxing is established through a great number of fatigue tests under five temperatures. Based on the database, two empirical parameters, that is, temperature factor (N_RT/N_HT) and life reinforcement factor (Re), are introduced to quantitatively characterize the coupling effects of high temperature and non-relaxing loads on fatigue life. The fatigue mechanisms under different conditions are compared via wide-angle x-ray diffraction tests and postmortem analysis. It reveals that the weakening of life reinforcement at high temperatures is closely related to the strain induced crystallization behavior of rubber.     

The effect of water immersion on fatigue crack growth of two engineering rubbers

Fatigue properties of two engineering rubbers have been measured in air and water. The fatigue crack growth rate, dc/dN, where c is the crack length and N the number of cycles, was measured as a function of tear energy for chloroprene rubber (CR) and natural rubber (NR). In general, the effect of water immersion on crack growth rates was relatively small. For NR, little effect of water immersion was seen and the fatigue threshold, which is the limit below which no mechano-oxidative fatigue growth will occur, was measured as 25 J/m² in both environments. For CR, a factor of two to three times lower crack growth rates was obtained in water compared to air, probably due to less influence of oxygen in water. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 941–946, 1998     

阿维菌素与城市污泥复合对小麦种苗生长的影响

探讨阿维菌素有机肥与城市污泥复合对小麦种苗生长的影响。采用小麦盆栽种植实验,将城市污泥与阿维菌素有机肥复合施入土壤中,对小麦种子萌发和种苗生长的形态指标进行测定。结果表明,45 g土壤中,阿维菌素的用量为5 g,城市污泥与土壤质量比为20%时,复合肥对小麦种苗的生长最好。对城市污泥的合理化利用具有重要意义。     

Influence of the molecular structure on slow crack growth resistance and impact fracture toughness in Cr-catalyzed ethylene-hexene copolymers for pipe applications

In this study we correlate parameters describing molecular structure (molar mass distribution, short chain branching content, intermolecular heterogeneity) of different ethylene-hexene Cr-catalyzed copolymers, with slow crack growth and rapid crack propagation resistances, respectively measured with Bent Strip and Charpy tests. The PTREF technique, coupled with classical techniques, was used. Two new indices were proposed to correlate mechanical properties and molecular structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 916–928, 2001     

Influence and CFD analysis of cooling air velocity on the purification of aqueous nickel sulfate solutions by freezing

Finite energy resources and their rapidly waning imprint necessitate a sustainable wastewater treatment method. Nature could be exploited to freeze wastewater in locations which experience subzero temperatures during winter. The two most vital components that influence the efficiency of natural freezing are the ambient temperature and air velocity. The turbulent and unsteady air‐cooled natural freezing is simulated for ice crystallization from 0.1 wt % and 1 wt % NiSO₄ (aq) solutions. The efficiency of natural freezing is tested for different air velocities (2 ms^?1, 5 ms^?1) and levels of undercooling (ΔT = 0.5°C, 1°C) from the freezing temperature of the corresponding solution. The airflow in the winter simulator is modeled by computational fluid dynamics to investigate its behavior and to assess its effect on freezing. © 2017 American Institute of Chemical Engineers AIChE J, 63: 200–208, 2018     

资源型功能磷复肥对水稻产量、养分吸收及抗折力的影响

通过2年田间试验研究了资源型功能磷复肥对晚稻生长、产量、养分吸收及抗逆性的影响。结果表明,施磷可显著促进水稻的生长发育、增加干物质积累和稻谷产量、提高水稻P、Ca、Mg的吸收量和抗折力;与高浓度磷肥处理(HP)相比,各资源型功能磷复肥处理(LP)增加稻谷产量309~689 kg/hm~2,分蘖初期P吸收量平均增加了13.1%~26.1%,收获期水稻地上部Ca、Mg的吸收量分别增加了14.3%~42.8%、20.6%~32.8%,抗折力显著增加6.8%~27.9%。各处理磷肥偏生产力无明显差异,但LP处理农学利用率显著增加21.0%~112.0%。     

气候和围护结构对空气源热泵空调系统性能的影响

基于TRNSYS软件建立了空气源热泵空调系统的仿真模型。基于该模型,分别利用我国五大气候区域的气象数据对空气源热泵空调系统进行了仿真分析,仿真结果表明,空气源热泵空调系统能够适用于我国除严寒地区之外的大多数地区,COP能够达到3.2~3.5。此外,还分析了建筑外围护结构传热系数对空气源热泵空调系统运行性能的影响,结果表明建筑负荷与系统能耗和外墙传热系数呈线性相关关系,降低外墙传热系数能够有效地降低系统能耗。     

聚天冬氨酸的改性对阻垢分散性能的影响

将聚琥珀酰亚胺(PSI)与天冬氨酸(ASP)、2-氨基乙磺酸(SEA)分别进行反应,对聚天冬氨酸进行改性,并对改性聚天冬氨酸的阻CaCO3垢、分散Fe2O3和缓蚀性能进行了评定。实验结果表明:在PASP分子结构中引入羧基可以提高其阻垢率,而磺酸基的引入则会降低其阻垢率,当引入羧基的改性聚天冬氨酸质量浓度为6mg/L时,阻垢率达到了100%;磺酸基的引入可以大大提高聚天冬氨酸的分散性能,加药质量浓度为10mg/L,分散Fe2O3时上清液最小透光率为40.3%;羧基的引入有助于缓蚀性能的提高,加药质量浓度为100mg/L时,比PASP的缓蚀率提高35%以上。     

含中微量元素的有机无机复混肥在防治水稻颖壳不闭合现象上的试验研究

江淮丘陵地区水稻颖壳不闭合现象造成水稻减产,通过田间试验,研究科学施用含有多种中微量元素的有机无机复混肥对防治水稻颖壳不闭合现象的效果。结果表明,与普通复合肥常规施肥方法的处理相比,通过科学施用有机无机复混肥使水稻颖壳不闭合发生率降低26.9～39.4百分点,并在促进水稻有效分蘖、穗粒数方面具有显著效果,水稻增产率为43.8%～66.6%,但在促进株高与穗长方面效果不明显。     

Influence of pH and Initial Glucose Concentration on the Growth of Saccharomyces cerevisiae Yeast Strain by Gravitational Field Flow Fractionation

Gravitational field-flow fractionation (GrFFF) was applied for the study of the growth of Saccharomyces cerevisiae yeast strain, in the presence or the absence of corn and wheat starch granules as immobilization carriers. Fermentations were conducted at different values of pH (3.0, 4.0, 5.0, and 6.0) and initial glucose concentration (177 g/L, 205 g/L, 247 g/L and 300 g/L) in order to find the most favorable situation for the growth and proliferation of Saccharomyces cerevisiae cells. The distinction of the phases of the yeast cell cycle was also succeeded by the same technique. The results indicate that the growth of yeast cells was enhanced at pH 5.0 and glucose concentrations of 177 g/L and 205 g/L. Higher glucose concentrations (247 g/L and 300 g/L) acted as an inhibitor to cell proliferation. Immobilization on wheat starch provided wider peak profiles, suggesting a broad size of cells and lower concentrations of haploid cells comparing to cells immobilized on corn starch granules. The determination of Michaelis-Menten constants for free and immobilized cells proved the higher affinity of immobilized cells towards the substrate. The values found were in good agreement with those reported in literature.