Biodegradable polyurethane materials from bark and starch. II. Coating material for controlled‐release fertilizer

Biodegradable polyurethane foams (PUFs) as coating materials for the controlled release of fertilizer were prepared from a four‐component system consisting of diisocyanate, polyester, Acacia mearnsi bark, and corn starch. Ammonium sulfate [(NH₄)₂SO₄] was used as a fertilizer to evaluate the effects of the preparation conditions on the release ratio. The release ratio of (NH₄)₂SO₄ decreased with an increasing amount of biomass in PUFs and increasing sizes of sample particles; the ratio increased with increasing doses of water, which was used as a foaming agent in the preparation of polyurethane, regardless of the amount of coating material. The remaining fertilizer in the polyurethane seemed to be released completely because the PUFs were degradable, to some extent, by soil microorganisms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2948–2952, 2002     

基于大豆蛋白的高回弹聚氨酯泡沫塑料的制备及性能研究

以大豆分离蛋白、高活性聚醚、聚合物多元醇、交联剂、发泡剂、泡沫稳定剂和混合异氰酸酯为原料,自由发泡、常温熟化制备了大豆蛋白基高回弹聚氨酯软泡。研究了大豆蛋白质(SPI)对聚氨酯泡沫物理性能、力学性能、孔结构和热性能的影响。结果表明:SPI添加量对泡沫物理和力学性能影响最大。随着SPI含量增加,泡沫的密度、尺寸稳定性提高,压陷硬度和舒适因子提高增大;回弹率下降,断裂伸长率减小,而拉伸强度先增大后减小。SPI能够提高聚氨酯的热稳定性,但最好低于150℃使用。     

Effect of foam density on the properties of water blown rigid polyurethane foam

Density is an important parameter that influences the properties and performances of rigid polyurethane foam (PUF). Rigid PUF with different densities were prepared by varying the amount of distilled water as blowing agent. This investigation reports the mechanical, morphological, water absorption, thermal conductivity, and thermal behavior of rigid PUF varying with the density, which controls the foam architecture. The density of the PUF decreased from 116 to 42 kg/m³ with an increase in the amount of water from 0.1 to 3.0 parts per hundred polyol by weight (phr), respectively. It was found that the mechanical properties of the PUFs changed with the foam density. The results of water absorption of the PUFs showed that water absorption increased with decrease in density, due to increase in the cell size and decrease in the cell‐wall thickness. The thermal conductivity measurements showed that the thermal conductivity decreased with increase in density. It was due to the decrease in cell size. The thermal analysis of the PUFs shows that the glass transition temperature increases with the decrease in foam density, but the thermal stability decreases with the decrease in foam density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

导电聚氨酯泡沫材料研究进展

从使用不同导电填料（炭黑、碳纳米管、石墨、金属、有机填料等）制备导电聚氨酯泡沫（PUF）材料的角度进行分析,总结了添加不同导电填料的复合泡沫制备方法以及对泡沫材料性能的影响,并论述了导电PUF材料在压阻材料、吸波材料、电磁屏蔽材料以及电极材料等领域的应用。分析表明,通过添加导电填料,可以改善PUF的静电现象,提高防静电、导电等性能并拓宽PUF材料的应用领域。     

Preparation and characterization of polyurethane based on dimer acid for environment-friendly controlled release fertilizers

ABSTRACT

The paper presents a new controlled release fertilizer coated by dimer acid-based polyurethane (PU). The structure and property of the sample were characterized. Results indicated that the polyether polyol modified PU (MPU) coating reduced water absorption rate by 72.1% after 29 d, and increased the cross-linking density by 23%, and decreased the coating porosity by 26%, Moreover, MPUFs and PUFs both exhibited excellent nutrient controlled release abilities, especially the MPUF possessed longer nitrogen release longevity (118 d,131%) compared with PUF (51 d). Thus, the high-performance MPUFs with environmentally friendly and excellent controlled release could be widely applied to agricultural fields.     

高塔保水缓释肥生产技术与产业化开发

将保水剂和肥料在材料和功能上进行复合一体化,开发研制了具有抗旱保水和缓释长效功能的肥料。该保水缓释肥不仅解决了目前农业生产上使用的肥料不具有吸水、保水的缺陷,而且还可解决高水溶性肥料养分速效、释放快、有效期短、养分释放与作物吸收不协调、易淋失固定或挥发等造成浪费资源和污染环境的问题。     

Branched polyols based on oleic acid for production of polyurethane foams reinforced with bamboo fiber

Fatty acids and bamboo fiber (BF) are abundant and renewable materials that have great potential application in the production of high-valued chemical products. In this work, polyurethane foams (PUFs) with remarkable mechanical and thermal properties were synthesized using OAPs (polyols-based on oleic acid (OA), an important fatty acid) and polymeric isocyanates. PUFs were reinforced with BF. Novel OAPs were prepared from OA through a process consisting of hydroxylation, carboxylation, and esterification. The strategy afforded branched polyols with high content of primary hydroxyls. Phthalic anhydride was used as a modifying agent to improve the properties of OAPs. Physicochemical properties of the polyols were characterized by standard methods (analyses of hydroxyl number, viscosity, acid value, density, and water content) and instrumental analysis (gel permeation chromatography, Fourier transform infrared spectroscopy, and thermogravimetry). The mechanical properties of polyurethane foams made from the OAPs were improved by applying modified BF as filler. With BF having particle sizes of 250–500 μm, the compressive strength of composite foams increased from 0.45 to 0.66 MPa, and the flexural strength increased from 0.66 to 0.77 MPa. Surface modification of BF by alkali could enhance the interfacial interaction between the reinforcing fibers and foam matrix, resulting in greater mechanical strength of the PUFs. It also improved the thermal stability and dynamic thermomechanical properties of PUFs.     

Polyurethane Composite Foams in High-Performance Applications: A Review

Polyurethane foam is a polymeric material having cellular structure. Multifunctional polyurethane foams reinforced with nanofiller have combined enhanced specific properties with density reduction. This article primarily considers important aspects of various foam processing techniques. Numerous nanofillers such as graphite, graphene, graphene oxide, carbon black, carbon nanotube, nanoclay, and inorganic nanoparticle have been reinforced in polyurethane foam. Particular attention is given to various categories of polymer/carbon nanofiller and polymer/inorganic nanofiller composite foams. Applications of polyurethane composite foams have been focused with relevance to aerospace and automotive industry, radar absorbing and electromagnetic interference shielding, oil absorbants, sensors, fire proof, shape memory, and biomedical materials.     

高表面活性矿物——一类新型的控释材料

高表面活性矿物是一类具有特殊物理化学性质的无机非金属材料,通常具有较高的表面活性和较大的比表面积,特殊的晶体结构使其具有独特的吸水性、可塑性、粘结性、强的离子交换性能和吸附性能.该文系统地评述了高表面活性矿物与农药分子、细菌病毒、蛋白质及肥料的相互作用机制,指出高表面活性矿物是一类新型的控释材料,对农药、化肥等具有较好的控释作用.     

MXene/PDMS composite foam with regulatable cell structures for improved EMI shielding performance

The construction of conductive network and the design of material structure are the key points of polymer-based shielding materials. Herein, we reported a MXene/PDMS composite foam material with adjustable cell structure and high efficiency electromagnetic interference (EMI) shielding. Few-layered MXene is used as a conductive filler to construct three-dimensional conductive networks by in situ chemical etching. Meanwhile, a series of polystyrene microspheres with different sizes were prepared by applying suspension polymerization method as templates to introduce different cell sizes and densities for PDMS-based materials. The density and EMI shielding performance of composites can be improved by adjusting the cell structure. Compared with the unfoamed MXene/PDMS composites, the composite foam in this work not only reduces the material density greatly but also improves the microwave absorption performance with smaller cell size. This method provides a simple and effective guide for changing material density and absorbing mechanism by introducing cell structure into polymer-based materials in the future.     

Effect of Continuous use of Sodic Irrigation Water with and without Gypsum, Farmyard manure, Pressmud and Fertilizer on Soil Properties and Yields of Rice and Wheat in a Long term Experiment

A long term field experiment was conducted for 8 years during 1994–2001 to evaluate the effect of N, P, K and Zn fertilizer use alone and in combination with gypsum, farmyard manure (FYM) and pressmud on changes in soil properties and yields of rice and wheat under continuous use of sodic irrigation water (residual sodium carbonate (RSC) 8.5 meq l⁻¹, and sodium adsorption ratio (SAR) 8.8 (m mol/l)^1/2 at Bhaini Majra experimental farm of Central Soil Salinity Research Institute, Karnal, India. Continuous use of fertilizer N alone (120 kg ha⁻¹) or in combination with P and K significantly improved rice and wheat yields over control (no fertilizer). Phosphorus applied at the rate of 26 kg P ha⁻¹ each to rice and wheat significantly improved the yields and led to a considerable build up in available soil P. When N alone was applied, available soil P and K declined from the initial level of 14.8 and 275 kg ha⁻¹ to 8.5 and 250 kg ha⁻¹ respectively. Potassium applied at a rate of 42 kg K ha⁻¹ to both crops had no effect on yields. Response of rice to Zinc application occurred since 1997 when DTPA extractable Zn declined to 1.48 kg ha⁻¹ from the initial level of 1.99 kg ha⁻¹. Farmyard manure 10 Mg ha⁻¹, gypsum 5 Mg ha⁻¹ and pressmud 10 Mg ha⁻¹ along with NPK fertilizer use significantly enhanced yields over NPK treatment alone. Continuous cropping with sodic water and inorganic fertilizer use for 8 years slightly decreased the soil pH_e and SAR from the initial value of 8.6 and 29.0 to 8.50 and 18.7 respectively. However, treatments involving the use of gypsum, FYM and pressmud significantly decreased the soil pH and SAR over inorganic fertilizer treatments and control. Nitrogen, phosphorus and zinc uptake were far less than additions made by fertilizer. The actual soil N balance was much lower than the expected balance thereby indicating large losses of N from the soil. There was a negative potassium balance due to greater removal by the crops when compared to K additions. The results suggest that either gypsum or FYM/pressmud along with recommended dose of fertilizers must be used to sustain the productivity of rice – wheat system in areas having sodic ground water for irrigation.     

Synthesis and properties of a novel superabsorbent polymer composite from microwave irradiated waste material cultured Auricularia auricula and poly (acrylic acid‐co‐acrylamide)

A novel superabsorbent polymer composite was successfully synthesized from waste material cultured Auricularia auricula (WMCAA) and poly (acrylic acid‐co‐acrylamide) (P(AA‐co‐AM)) using microwave irradiation. Optimal synthesis conditions were determined by investigating the water absorbency of the superabsorbent composite. The effects associated with weight ratios of WMCAA, acrylamide (AM) monomers, initiators, and acrylic acid (AA) crosslinkers, as well as the degree of neutralization of AA were examined. The maximum water absorbencies were found to be 1548 g/g (distilled water) and 72 g/g (0.9% NaCl solution). Fourier transform infrared spectroscopy (FTIR) was applied to determine the molecular structure of the superabsorbent composite, and scanning electron microscopy (SEM) was used to demonstrate the characteristic compact and porous structure of the material. Further studies conducted via transmission electron microscopy (TEM) revealed the formation of a novel interpenetrating polymer network structure. Thermogravimetry/differential thermal (TG/DTG) analysis demonstrated improved thermal stability in the composite material compared with WMCAA. Additionally, high water absorption rates observed in the polymer during the swelling process indicated first‐order kinetics. The water absorption and adsorption of the superabsorbent composite were studied in a variety of fertilizer solutions, revealing an indirect relationship between water absorbing ability and fertilizer concentration. Conversely, a direct relationship was observed between absorbed fertilizer and fertilizer concentration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3674–3681, 2013     

Rigid polyisocyanurate–waterglass foam composite: Preparation,mechanism, and thermal and flame‐retardant properties

A rigid polyisocyanurate–waterglass foam (PIWGRF) composite was prepared with polyaryl poly(methylene isocyanate) and waterglass (WG) as the main materials; water as a blowing agent, and no polyols. We speculated the formation mechanism of the PIWGRFs on the basis of the analysis of experiment data, scanning electron microscopy characterization, and transmission electron microscopy. The results show that three‐dimensional nanoflakes derived from the cured WG was observed; this was connected with polyisocyanurate by secondary bonding (Si? O? H?N). Thermogravimetric testing indicated that the thermal stability and residual mass (34%) of the PIWGRFs were significantly higher than those of rigid traditional polyurethane foams (T‐PUFs). When the core density of the PIWGRFs was 32.6 kg/m³, the strength was up to 162.9 KPa by excessive filling. The flame retardancy of the PIWGRFs, including the time to ignition, heat‐release rate, total smoke of release, and limiting oxygen index, was obviously better than that of the T‐PUFs. The structure of the residual char was more dense and orderly; this was also an effective barrier layer. The reason was attributed to the fact that the WG did not contain combustible elements. So, the PIWGRFs had excellent thermal stability, flame retardancy, and environmental friendliness. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46182.     

负载氧化镧泡沫玻璃脱除水中氟离子

饮用水中过量的氟会对人体造成危害,因此发展成本低、高效率除氟材料对于高氟地区饮用水安全和含氟废水处理很有必要。以泡沫玻璃为载体,采用浸渍法制备了泡沫玻璃负载氧化镧的复合材料。对复合材料组成、表面形貌、镧的溶出率和除氟效果做了表征。结果表明：负载氧化镧7%（质量分数）的泡沫玻璃除氟效果最佳,用100 g的该材料就可以将600 mL废水中的氟离子质量浓度从32 mg/L降至1 mg/L以下,达到了饮用水标准。使用过的复合材料通过草酸溶液处理,于600 ℃下热解,可以使复合材料再生。     

提高肥料利用率化工部门能做些什么？

介绍了中国肥料利用率状况、所施肥料的去向及土壤中养分的积累与亏损。据估计,中国自１９８５～１９９６年,约有９９００万吨Ｎ被淋失和逸散,６０００万吨Ｐ２Ｏ５和１４００万吨Ｋ２Ｏ固定于土壤中。如何提高肥料利用率是中国化学肥料工业紧迫的课题,针对不同类型化肥厂提出了生产控制释放肥料、腐植酸螯合尿素、稳定的碳酸氢铵、部分酸化磷矿复合肥料、完全水溶性复合肥料以及熔融钾镁肥的途径,以提高肥料利用率。     

含有短切导电纤维聚氨酯泡沫塑料的吸波性能研究

通过对一种含导电短纤维的聚氨酯(PUR)泡沫塑料吸波性能的研究,探讨了纤维吸收剂的电导率、含量和泡沫塑料试样厚度对PUR泡沫塑料吸波性能的影响。结果表明,在一定范围内,纤维电导率增大可使PUR泡沫塑料对电磁波的损耗增加;纤维含量增大可增加其谐振子数目,有利于衰减电磁波;试样厚度增加可使PUR泡沫塑料吸波性能增强,在Ka波段尤为明显。     

建议推广适用于大田作物的缓释／控释肥料

我国当季化肥利用率较低,不仅浪费人力、物力、财力,而且有害于生态环境。影响化肥利用率的因素较多,除使用不当外,还有化肥养分释放不符合作物需肥规律,如养分释放过快使作物来不及吸收而损失等。为此,各国致力于开发缓释/控释肥料。国外开发的缓释/控释肥料由于成本高,只能用于非大田作物。我国根据国情,致力于开发低成本可用于大田作物的缓释/控释肥料,目前已有不少科研院校取得了可喜的成绩,建议结合水稻施肥技术开展推广示范工作。     

Functionally graded dry adhesives based on f ilm-terminated silicone foam

A dry functionally graded adhesive (FGA) based on f ilm-terminated silicone foam was developed utilizing the foam's capacity of absorbing a large amount of energy to deliver high adhesion. The fabrication technique is based simply on sugar cube templating of common elastomers followed by film termination of the elastomer cubes using the same material. Dependences of the pull-off adhesive force and energy release rate on the preload and foam thickness were systematically investigated through a series of axisymmetric indentation/de-bonding tests. The contribution of the foam backing layer to the overall compliance and adhesion was analysed and discussed. The developed elastic f ilm-terminated structure has remarkable enhancement in pull-off force and work of adhesion, which can be employed in the transport of delicate objects as demonstrated in the pick and place of a silicon wafer. Furthermore, the proposed foam-based FGAs can be readily detached from the adherent surface by applying a slight shearing deformation. The research findings provide insights in understanding the role of mechanical graded properties in adhesion and can have technical implications in the development of a simple but effective dry adhesive material for mounting and transporting objects by automated robotic devices.     

阻燃剂DOPO-FR的合成及阻燃聚氨酯的性能研究

以苯胺、苯甲醛、9,10二氢9氧杂10磷杂菲10氧化物（DOPO）为原料合成了一种新型阻燃剂9,10二氢9氧杂10磷杂菲10氧化物4\[(苯胺)甲基\]苯（DOPO FR）,并与磷酸三乙酯(TEP)、膨胀石墨(EG)复配制备了阻燃聚氨酯泡沫材料。采用红外光谱分析仪、核磁共振分析仪对DOPO FR的化学结构进行表征,并利用极限氧指数、热重分析仪等对阻燃聚氨酯泡沫材料进行性能分析。结果表明,DOPO FR质量为多元醇的20 %,聚氨酯泡沫材料的极限氧指数就可达24.7 %;DOPO FR的加入提高了聚氨酯泡沫的力学性能和热稳定性;EG、TEP、DOPO FR三者协同阻燃可使聚氨酯泡沫的极限氧指数达到32 %。     

汽车用新型吸声材料——稻草秸秆板吸声性能的测定

研究了用可再生资源稻草秸秆板替代汽车用吸声泡沫塑料。应用L₉(3⁴)正交试验研究了稻草秸秆长度、秸秆板密度、热压时间对秸秆板的吸声性能的影响,结果表明秸秆板密度是影响稻草秸秆板吸声系数的主要因素。通过测试发现相同厚度的稻草秸秆板平均吸声系数大于泡沫塑料,当用稻草秸秆板替代XMQ 6608客车原发动机隔声罩内的泡沫塑料时,新罩的降噪效果优于原罩,试验结果证明:轻质稻草秸秆板是能用作汽车吸声材料的。