含产水剂硅烷交联聚乙烯的制备及其性能研究

将硬脂酸(HSt)和氧化锌(ZnO)作为产水剂,通过单螺杆挤出机制备出硅烷交联聚乙烯(SXPE)。通过测量体系凝胶含量、拉伸强度、断裂伸长率,研究了体系的交联度和力学性能,并采用SEM观察挤出物的表面质量,考查其加工性能。结果表明:无需水煮交联工序,添加2.0～3.0phr产水(剂HSt:ZnO=1:1)则能够使SXPE的凝胶含量在一周时间内可达到80%;当产水剂含量为3.0phr时,体系的拉伸强度提高了18.8%,断裂伸长率增加了25.3%。产水剂的加入对熔体加工有润滑作用适,量的产水剂可使挤出物的表面光滑。

产水剂对硅烷接枝LDPE的交联作用

采用HAAKE流变仪作为反应器,将不饱和硅烷熔融接枝到低密度聚乙烯(LDPE)上,然后将产水剂加入该体系,深入研究了流变转矩的变化规律。结果表明,硅烷用量一定,交联剂过氧化二异丙苯(DCP)用量很小时(0.005phr),熔体的扭矩随时间增长缓慢;当DCP用量大于0.015phr,熔体的扭矩都呈现先升后降的趋势,且随着DCP用量的提高,扭矩增大,达到最高峰的时间提前;加入某些产水剂后,熔体的扭矩增长很快,特别是加入磷酸二氢钠或三聚氰胺甲醛树脂干胶粉产水剂,熔体扭矩均增加了一倍多,凝胶质量分数测定结果也证明了产水剂可以明显地提高LDPE的交联速度。

产水剂对硅烷接枝聚乙烯交联作用的初步探讨

采用 HAAKE 流变仪作为反应器,将不饱和硅烷熔融接枝到低密度聚乙烯(PE-LD),然后将产水剂加入该体系,对流变转矩的变化规律作了详细的探讨。实验结果表明硅烷用量一定,交联剂过氧化二异丙苯(DCP)含量在0.005质量份时,熔体的扭矩随时间增长缓慢;当 DCP 含量大于0.015质量份时,熔体的扭矩都呈现先升后降的趋势,并且随着 DCP 含量的提高,扭矩增大,达到最高峰的时间提前;某些产水剂加入后,熔体的扭矩增长很快,特别是加入磷酸二氢钠或三聚氰胺甲醛树脂干胶粉产水剂,PE-LD 熔体扭矩均增加了一倍多,凝胶含量测定数据佐证了产水剂可以明显地提高聚乙烯的交联速度。

氧化锌对硅烷交联聚乙烯的影响

利用叔丁基过氧化特戊酸酯作为引发剂,与氧化锌以及乙烯基三甲氧基硅烷以一定比例配合,制备了硅烷自交联聚乙烯。利用红外光谱表征了接枝产物,并确定了最佳配方和工艺。探讨了ZnO、引发剂的含量、加工温度对体系的接枝率、结晶度、凝胶含量以及力学性能的影响。结果表明:随着加工温度的升高,接枝率与凝胶含量均降低,结晶度增大,材料的力学性能则呈现先下降后上升的趋势;而随着ZnO和引发剂用量的增加,材料的接枝率和凝胶含量以及力学性能均呈先上升后下降的趋势;在温度为170℃,PV和ZnO含量为0.25份时,材料的结晶度最低,接枝率和凝胶含量最高,拉伸强度最高,为22.58 MPa。

制备工艺对硅烷交联超高分子量聚乙烯综合性能的影响

本文在传统硅烷交联方法的基础上,结合超高分子量聚乙烯(UHMWPE)的特点,对接枝和交联工艺分别进行改进:接枝过程中,在UHMWPE出现亚稳性的工艺条件下,利用柱塞挤出在较低温度和压力下完成了UHMWPE的硅烷接枝过程的连续操作;交联过程中,预先在硅烷接枝UHMWPE中添加合适的产水剂一水合草酸钙,利用模压过程中产水剂在聚合物内部产生水从而实现UHMWPE硅烷接枝料的原位水解缩合交联反应,省去传统硅烷交联聚烯烃需经过水煮或蒸汽处理的过程。研究了工艺改进后所制备的硅烷交联UHMWPE的凝胶含量、热性能以及机械性能随产水剂用量的变化规律,材料的综合性能更优异。

Effects of Super Absorbent Polymers on Yield and Water-saving and Drought-escaping Mechanism in Spring Maize

The effects of super absorbent polymers （SAP） on yield as well as water-saving and drought-escaping mechanism in spring maize in the seasonal drought region were studied. As shown by the results, during the seasonal drought in southern China, SAP treatment promoted the soil moisture, improved the capability of absorption and transportation of roots, promoted physiological and biochemical functions, increased the chlorophyll content, photosynthetic rate and intercellular CO2 concentration, and reduced the stomatal conductance and transplre.tion rate. As a result, the economic characters of spring maize were improved, and the yield was increased.

硅烷自交联聚乙烯的制备与性能研究

通过熔融共混将产水剂加入到硅烷交联聚乙烯中,制备出室温下可进行自交联的硅烷交联聚乙烯材料。采用热重分析仪、平板流变仪、万能试验机对硅烷自交联聚乙烯的结构、性能进行表征。结果表明,产水剂的加入可以在自然放置的条件下逐步提高材料的凝胶含量,最终达到水煮工艺处理同样的效果;乙酸锌的促进效果最好,兼具高凝胶含量的同时,使材料的力学性能、热稳定性、储能模量提高。

乙烯-醋酸乙烯共聚物的室温硅烷交联研究

采用A-171作为硅烷偶联剂,过氧化二异丙苯作为引发交联剂,二月桂酸二丁基锡作为催化剂,硬脂酸/氧化锌作为产水剂,氢氧化镁作为阻燃剂对乙烯-醋酸乙烯酯进行室温硅烷交联。结果表明,此工艺生产的低烟无卤阻燃乙烯-醋酸乙烯酯具有良好的力学性能和阻燃性能。

Enhanced photocatalytic H2-production activity of WO3/TiO2 step-scheme heterojunction by graphene modification

Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.

Photo-depositing Ru and RuO2 on Anatase TiO2 Nanosheets as Co-catalysts for Photocatalytic O2 Evolution from Water Oxidation

TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocatalysts. The structural features of the catalysts were characterized by X-ray di raction, transmission electron microscopy, inductively cou-pled plasma atomic emission spectrum, and H2 Temperature-programmed reduction. The photocatalytic property was studied by the O2 evolution from water oxidation, which was examined with respect to the in uences of Ru contents as well as the oxidation and reduction treatments, suggesting the charge separation effect of the Ru species co-catalysts on di erent facets of TiO2 nanosheets. In contrast to Ru/TiO2 and RuO2/TiO2 with the single deposited co-catalyst, the optimized catalyst 0.5%Ru-1.0%RuO2/TiO2 with dual co-catalysts achieved a much improved catalytic performance, in terms of the synergetic effect of dual co-catalysts and the enhanced charge separation effect.

Effects of SSA Dosages on Seedling Quality and Yield by Mechanical Transplanting

[Objective] The aim was to research the influence of gradient dosages of seedling-strengthening agent （SSA） on rice seedling quality and yield. [Method] The influence of four dosages of SSA on late rice seedling quality and yield was investi- gated, using Oryza sativa cv. Yongyou 9 and Huanghuazhan as test materials. [Re- sult] The results showed that applying SSA significantly increased several indexes of seedling quality including the leaf age, basal stem width and dry matter weight. In addition, SSA greatly increased the rice yield, mainly through influencing two yield component factors, effective panicle number and grain number per panicle. [Conclu- sion] SSA was beneficial to nurse strong seedling which satisfied mechanical trans- plant and improve yield. Considered both seedling quality and yield trait, the optimal SSA dosage is 50 g/m2 under this cultivating condition.

The flocculation efficiency of compound bioflocculant by flocculant-producing bacteria

The flucculation efficiency of compound bioflocculant produced by flocculant-producing bacteria was investigated in this study. Cheap cellulose was selected as the substrate for the production of a lower cost bioflocculant. The end product of cellulose decomposing bacteria was utilized as substrate for flocculant-producing bacteria. The optimum fermentation conditions were determined as follows： the initial fermentation and fermentation time was 5 d and 1 d respectively, the temperature was 30 ℃, the rotation speed was 120 r/min, the amount of CaCl2 solution （ 10% ） was 1.5 ml/L. The flocculation test indicated that the bioflocculant had high efficiency in the removal of the turbldity raw water from Songhua River.

The Characteristics of a Sorption-enhanced Steam-Methane Reaction for the Production of Hydrogen Using CO_2 Sorbent

The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at different operation conditions were calculated using an iterative method. It was found that with Ca(OH)2 as the CO2 sorbent, the concentration of CO2 adsorption was reduced in the product stream, that gave rise to higher methane conversion and higher H2 concentration. An experimental setup was built to test the theoretical calculation. The effects of sorbents and the particle size of Ca(OH)2 on the concentration of CO2 and H2 were investigated in detail. Results showed that the reactor packed with catalyst and Ca(OH)2 particles produced H2 concentration of 94%. It was nearly 96% of the theoretical equilibrium limit, much higher than H2 equilibrium concentration of 67.5% without CO2 sorption under the same conditions of 500℃, 0.2 MPa pressure and a steam-to-methane ratio 6. In addition, the residual mole fraction of CO2 was less than 0.001.

Remediation Effects of a Novel Soil Conditioner onCadmium and Arsenic Contaminated Soil in Early-Season Paddy Field

To investigate the effects of“Runbang”soil conditioner on simultaneously decreasing cadmium(Cd)and arsenic(As)in early-season paddy field,a typical red mud field in Hunan Province was selected for monitoring the dynamic changes of Cd and As contents in early-season rice plants and soils,plus the soil physical-chemical properties and rice yields.Results of the field experiments indicated that the soil conditioner could significantly reduce Cd and As contents in soil and rice grain,whereas it could increase rice yield.Applying Runbang soil conditioner(1500~2100 kg/hm^2)to paddies brought about a reduction of 23.7%~44.8% and 24.3%~40.5% in available Cd and As contents of the soil,an increase of 0.9~1.1 units in soil pH value,a decline of 35.6%~51.1% and 22.0%~40.6% in Cd and As contents of rice grains,and a rise of 2%~5% in rice yields,respectively.

Extraction of Theanine from Waste Liquid of Tea Polyphenol Production in Aqueous Two-phase Systems with Cationic and Anionic Surfactants

Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactanttwo-phase system （ASTP） with cationic surfactant （CTAB） and anionic surfactant （SDS）. Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the Partition coefficient and extraction rate only change a littlewhen the concentration of theanine is above 0.2 g.L-＇. With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable ef- fect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom ohase, since the orotein and the saccharide enter the bottom nhase with theanine.

Improvement of Rice （Oryza sativa L.） var. Ciherang and Cempo Ireng Productivity Using Gamma Irradiation

Rice is the source of important food in the world. The demand of rice tends to increase every year, thus research to increase genetic variation of rice by gamma irradiation has been conducted. This research aimed to study the influence of gamma irradiation doses on the vegetative growth, yield and quality. The randomized completely block design was used with two factors --gamma irradiation doses and varieties. Two rice varieties were Ciherang and Cempo Ireng, while doses of gamma irradiation consisted of six levels： 0, 100, 200, 300, 400 and 500 Gy. The results indicated that the treatment of 200 Gy gamma irradiation to Ciherang could improve the number of grains/panicle, protein content, degraded plant height and amylose contents. Gamma irradiation to Cempo Ireng at dose of 200 Gy could improve the number of grains/panicle, 1,000 grain weight, while it decreased days to 50% heading and plant harvest age.

Phytotherapic Potentials of Xylopia aethiopica Dried Fruits （Grains of Selim） as Additive in Broiler Production

Xylopia aethiopica dried fruits （gains of selim） as an additive in starter broilers production was investigated. For this purpose, a total of 195-day old broiler chicks （Arbor acres） were randomly allocated into five treatments groups with 39 chicks and three replicates of 13 chicks in each. Blended grains of selim was given through drinking water on treatments T2, T3, T4 and T5 at concentrations of 0.4, 0.6, 0.8 and 1,0 g/L, while chicks on treatment T1 （control） received antibiotics （Doxy-gen 20/20 WSP： Doxycycline hyclate 200 mg and Gentamicine sulfate 200 mg） at 0.3 g/L of water. All the experimental chicks were fed ad libitum with diet containing 23% crude protein and 2,851.55 kcal/kg metabolizable energy for 28 d. The results revealed that there were similarities （P 〉 0.05） in final body weight, total weight gain, daily weight gain, total feed intake, daily feed intake and feed conversion ratio among the treatments. There were significant （P 〈 0.05） differences in the microbial count of faeces before the birds received antibiotics and grains of selim, but count were similar （P 〉 0.05） after grains of selim and antibiotics were administered. Cost of total feed consumed, cost of per kg feed and cost of per kg weight were significantly （P 〈 0.05） higher in treatment T1, but cost differential and relative cost benefit were similar （P 〉 0.05）. Results indicate that grains of selim have antimicrobial and anthelminthic properties, and promote growth in broiler chickens.

Gas-phase dehydration of glycerol over commercial Pt/γ-Al_2O_3 catalysts

Gas-phase dehydration of glycerol to produce acmlein was investigated over commercial catalysts based on γ-Al2O3, viz. A-64, A-56,1-62, AP-10, AP-56, AP-64 and KR-104. To understand the effect of Cl anions, HCl-impregnated sup- ports have been investigated in the dehydration reaction of glycerol at 375 ℃. For comparison, various H-zeolites were also examined. It was found that the glycerol conversion over the solid acid catalysts was strongly dependent on their acidity and surface area. And the relationship between the catalytic activity and the acidity of the catalysts was discussed. The outstanding properties of Pt/γ-Al2O3 catalyst systems for the dehydration of glycerol were revealed. Pt/γ-Al2O3 catalyst （AP-64） showed the highest catalytic activity after 50 h of reaction with an acrolein selectivity of 65% at a conversion of glycerol of 90%. Based on these results, catalysts based on γ-Al2O3 appear to be most promising for gas phase dehydration of glycerol.

Effect of Drip Irrigation Intervals and Some Antitranspirants on the Water Status, Growth and Yield of Potato （Solanum tuberosum L,）

In order to reduce the quantity of water applied by irrigation, increase the water use efficiency and determine the appropriate period for irrigation potato crop, a field experiment was implemented at vegetables field, Department of Plant Production, Agriculture Technical College, Mosul, Iraq, during spring season of 2014. This study involved four irrigation intervals （3, 4, 5 and 6 d） under drip irrigation system, with spraying by five antitranspirant substances （control, kaolin 5 g/L, MgCO3 3 g/L, liquid paraffin 2% and Nu-film 17 1%）, which subjected in a factorial experiment within split plot system in a randomized complete block design with three replications. The results showed that increasing irrigation intervals from 3 d to 6 d decreased the total water content of the leaves from 83.59% to 81.81%, the rate of relative transpiration from 0.174% to 0.162%, stomata area from 1.620 lam2/stomata to 0.921 ~m2/stomata, plant yield from 542.22 g to 425.80 g, total yield of tubers from 25.808 tons/ha to 20.253 tons/ha and marketable yield of tubers from 24.471 tons/ha to 18.822 tons/ha, whereas caused an increase in the leaf water deficit from 19.19% to 23.86% and water use efficiency from 8.63 kg/m3 to 13.32 kg/m3. Spraying potato plants with liquid paraffin 2% led to the highest total water content 83.37%, stomata area 1.466 ~tm2/stomata, the lowest relative transpiration 0.152%, the lowest leaf water deficit 20.33%, the highest plant yield 509.22 g, total yield 24.236 tons/ha, marketable yield 22.770 tons/ha and water use efficiency I 1.83 kg/m3. On the other hand, the interaction treatments between irrigation intervals and antitranspirants resulted in a significant effect in many studied parameters.

ahospholipase Applications in Cheese Production

Phospholipase is an enzyme that hydrolyzes phospholipids releasing a variety of products, like for example lyso-phospholipids, free fatty acids, di-acylglycerols, choline phosphate and phosphatidates, depending on the site of hydrolysis. In cheese production, lysophospholipids act as surface-active agents in the cheese curd, helping emulsification of water and fat during processing and reducing syneresis. Phospholipases are more specific and have little or no activity toward di- or triglycerides. As a result of phospholipid hydrolysis, flavor defects do not occur due to the main formation of palmitic, oleic, and stearic acids, which are non-volatile short chains fatty acids. According to the scientific studies the use of phospholipase is able to increase the yield of cheese and reduce the environmental impacts of cheese production. Protein and fat largely determine cheese yield. Depending on the milk composition, 75% to 78% of milk protein and 85% to 95% of milk fat are entrapped in the cheese curd. The remaining protein and fat are lost in the whey and, to a lesser extent, in the brine. Crucially in the production of pasta filata cheese fat losses occur in the hot stretching step, where the fresh curd is molded and stretched in hot water. The lysophospholipid-casein complexes should be studied to understand the mechanism leading to cheese yield improvements.