聚丙烯纤维滤材气溶胶样品的浸取-灰化-消解前处理方法

在《全面禁止核试验条约》(CTBT)体系的放射性核素监测中,需要对气溶胶可疑样品进行前处理,以便进行详细分析。这类气溶胶样品基体质量大,待测元素多且化学性质差异大,单用某一种前处理方法难以保证回收率。本工作提出了浸取-灰化-消解联用的方法,即微波密闭浸取易挥发元素、灰化除去滤材基体、再用微波密闭消解溶解难溶元素的方法。实验用聚丙烯纤维滤材制备了模拟样品,以铯、铈和锆为代表研究了浸取压力、功率、时间、灰化条件以及消解酸种类和用量等条件对回收率的影响。实验结果表明:在最佳条件下,外加于气溶胶样品的铯、铈和锆可以定量回收。

静电效应对聚丙烯滤材过滤效率的影响

本文对聚丙烯带静电滤材在不同辐照剂量下的过滤效率进行了实验测定。研究了辐射对聚丙烯带静电滤材过滤性能的影响，提出了聚丙烯滤材在核工程空气过滤净化领域的应用条件。利用辐照消电法求出了纤维带电密度，计算了聚丙烯滤材在碰撞、截留、扩散及静电作用下的过滤效率。结果表明，理论计算值与实验值符合良好，二者均表明静电效应在聚丙烯滤材对固体气溶胶过滤中起着主导作用。

The Effect of Silane Grafted Polypropylente on the Property of Different Filler/Polypropylene Composites

Aim To determine the effect of silane grafted polypropylene on the property of different filler/polypropylene composites. Methods Polypropylene (PP) composites filled with talc(Ta), baryta sulfate and calcium carbonate coupled with silane grafted polypropylene (PP-g-Si) were made, their mechanical properties and thermal properties were investigated, respectively. Results As compared with the non-coupled composites, the mechanical properties of PP/Ta/PP-g-Si composites were improved to some extent, though the values of tensile modulus and the strain at peak were decreased. But for PP/BaSO4 and PP/CaCO3 composites, the values of their mechanical properties varied slightly or even decreased with increasing PP-g-Si content within the experimental component. Meanwhile, PP-g-Si also affected the melting and crystallization behavior of PP in the composites. Conclusion PP-g-Si offers compatibilization in PP/Ta composites, but offers no-compatibilization in PP/BaSO4 and PP/CaCO3 composites within the extent of the present range of PP-g-Si, which shows that PP-g-Si can be used as the macromolecular coupling agent of PP and Ta composite.

Autefa:聚酯纤维和黏胶纤维用高效打包机

德国Autefa Solutions集团联合3家占市场主导地位的纤维制造商,开发出新一代打包机——Nonstop-Ultra(图1)。该打包机可满足聚酯纤维和黏胶短纤维生产所需的产能和质量等要求,且具有劳动力成本大幅降低、安装利用率高及成本回收时间短等特点。手工操作Nonstop-Ultra打包机,产量为35包/h,若与AD-Wrap罩膜包装机联合生产。

Study on the Properties of Microcapsulated Chlorocyclophosphazene Polypropylene Composites

Microcapsulated chlorocyclophosphazenes were synthesized,and then microcapsulated chlorocyclo- phosphazene/polypropylene(PP)composites were prepared.The results showed that microcapsulated chlorocyclo- phosphazene had good high thermal stability through thermogravimetric analysis(TGA).The flammability and mechanical properties of microcapsulated chlorocyclophosphazene/polypropylene composites were investigated by limiting oxygen index experiment,UL 94V flame retardancy test,cone calorimetry,tensile experiment,and impact test,respectively.It was shown that the microcapsulated chlorocyclophosphazene/PP composites had better tensile strength,impact strength,flame retardant properties and smoke suppress properties compared with chlorocyclo- phosphazene/PP composites.

Effect of chemical modification on the properties of wood/polypropylene composites

Aluminate-based coupling agent was added as a compatibilizer to make the chemical modification of wood powder. The mechanical properties and morphology of wood powder/polypropylene composites were studied. The results showed that the compatibilizer can increase the impact strength of the wood/polypropylene composites, but it has a slightly negative effect on the tensile and flexural strength. For dynamic mechanical properties and Differential Scanning Calorimetry, Aluminate-based coupling agent can slightly increase the storage modulus and loss modulus, and decrease the melt point and the Calorie of Melt. Scanning electron microscopy showed that Aluminate-based coupling agent had a stronger affinity between the wood and polypropylene surfaces. These results suggested that Aluminate-based coupling agent may play a useful role in improving wood powder/polypropylene composites properties.

Superabsorbent Capability and High Retention Ability of China Clay(Kaolinite)/Polyacrylic Acid Composites for Aqueous Solution

Majority of superabsorbent polymers (SAPs) yet reported either have low gel strength or high production cost. Therefore, we synthesized a novel polyacrylic acid-grafted China clay (Kaolinite) super-absorbent polymer composite (SAPC) with high thermal stability, low cost of production and superior sorption and retention capability for water and salt solution. The resulting SAPCs were extensively characterized and analysed by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results suggested that the composites were thermally stable. Water absorbency increased with increase of clay content up to 45%, while further increase in clay content decreased the water absorbency. Percentage of acrylic acid (AA) and clay by weight shows the optimum absorbency in 35% and 40% respectively. Crosslinker and initiator contents were optimized to be 0.5% and 0.3% by weight respectively. The resulting polymer composite showed high water absorbency of about 785 g/g and 103 g/g of 1% NaCl solution with above 90% retention ability at 50 oC.

Effect of concentration of ATH on mechanical properties of polypropylene/aluminium trihydrate(PP/ATH) composite

Aluminium trihydrate(ATH) is being extensively added to polypropylene(PP) to make a fire retardant composite. Blends of PP/ATH composite are more fire resistant as compared to pure PP. Percentage proportion of both the constituents in the final composite depends upon the application. Improvement in the fire retardant properties of such composites have been studied and published in literature but effects on mechanical strength have not been addressed. The effect of concentration of ATH on the strength of PP/ATH composite was presented. The tensile, flexural and fracture properties were studied and discussed. Experimental tests, ASTM analytical formulae and finite element approach were used. It has been found that increase in ATH has an inverse effect on the mechanical strength.

Influence of Wind Speed on Heat Flow through Polypropylene Insulating Material

The heat transfer properties of polypropylene insulation at different ambient temperature against wind were analysed. A theoretical model of the combined conductive, convective and radiative heat flow through fibrous insulating material was presented. Detail study was carried out by using the finite element method. The theoretical results are in accordance to the experimental results which were accomplished in an artificial climate chamber.

Dyeing of Polypropylene Fibers with Vat Dyes

Polypropylene fibers have been extensively used in a variety of/products, including carpets and upholstery, due to their non-absorbency, good weather resistance, good resistance to macroorgamsms and so on. Because of their hydrophobic and highly crystalline nature, those well-established conventionai dyeing processes are difficult to apply to unmodified polypropylene. Colors of polypropylene fibers are primarily obtained by mass coloration which has the disadvantages of limited number of colors available and difficulties in inventory control due to the rapidly changing color needs of the market. In this paper, the use of vat dyes to dye polypropylene fabrics is investigated. Seventeen vat dyes were screened and factors influencing uptake of dyes by polypropylene fabrics were studied.

Effect of maleic anhydride grafted styrene-ethylene-butylene-styrene （MA-SEBS） on impact fracture behavior of polypropylene / wood fiber composites

MA-SEBS as compatibilizer and impact modifier was incorporated into Polypropylene/Wood Fiber （PP/WF） to enhance interface adhesion and impact strength of the composite. The effect of MA-SEBS content on the impact fracture behavior of PP/WF composites was studied. The impact properties of composites with 8% MA-SEBS reached the maximum value. And further increasing of MA-SEBS content to 10% did not improve the fracture toughness, but improved the stiffness of composites by DMA analysis. This was attributed to the improved PP/WF adhesion. As the MA-SEBS content is more than 8%, the molecule interaction of PP and WF was expected to much stronger than lower MA-SEBS. Scanning electron microscopy （SEM） was performed to analyze the impact fracture surface and showed a stronger affinity for the wood surfaces.

延长保存食品的新方法

最近，美国一公司研制出一种可进行微波加热储存于托盘内的低酸性长期保存食品。它采用聚丙烯基材。加工时将食品装入托盘，在接近真空状态密封后以250°F蒸煮杀菌，可保食品的储藏期在常温下提高到12～18个月。

Experimental Study on the Mechanical Properties of Novel Plate-knitted Composite Tracheal Stents

A new knitted composite artificial tracheal stent made of polyglactin(PGLA) and polypropylene (PP) filaments for reinforcement and regeneration of human trachea has been developed by plated-knitting technique on a small-diameter circular knitting machine.Both tensile and compressive tests were carried out to determine the Young's modulus and the critical pressure corresponding to crushing of the stent.The experimental results confirmed that the new type of knitted composite artificial stent is mechanically feasible.

Microencapsulation of stearic acid with polymethylmethacrylate using iron(Ⅲ) chloride as photo-initiator for thermal energy storage

Aiming to identify the validity of fabricating microencapsulated phase change material(PCM) with polymethylmethacrylate(PMMA) by ultraviolet curing emulsion polymerization method using iron(III) chloride as photoinitiator,SA/PMMA microcapsules were prepared and various techniques were employed to determine the ignition mechanism,structural characteristics and thermal properties of the composite.The results shown that the microcapsules containing SA with maximum percentage of 52.20 wt% formed by radical mechanism and only physical interactions existed in the components both in the prepared process and subsequent use.The phase change temperatures and latent heats of the microencapsulated SA were measured as 55.3 °C and 102.1 J·g^(-1) for melting,and 48.8 °C and 102.8 J·g^(-1) for freezing,respectively.Thermal gravimetric analysis revealed that SA/PMMA has good thermal durability in working temperature range.The results of accelerated thermal cycling test are all shown that the SA/PMMA have excellent thermal reliability and chemical stability although they were subjected 1000 melting/freezing cycles.In summary,the comparable thermal storage ability and good thermal reliability facilitated SA/PMMA to be considered as a viable candidate for thermal energy storage.The successful fabrication of SA/PMMA capsules indicates that ferric chloride is a prominent candidate for synthesizing PMMA containing PCM composite.

Preparation of Mesoporous Carbons from Acrylonitrile-methyl Methacrylate Copolymer/Silica Nanocomposites Synthesized by in-situ Emulsion Polymerization

Acrylonitrile-methyl methacrylate （AN-MMA） copolymer/silica nanocomposites were synthesized by in-situ emulsion polymerization initiated by 2,2＇-azobis（2-amidinopropane） dihydrochloride absorbed onto colloidal silica particles, and the mesoporous carbon materials were prepared through carbonization of the obtained AN-MMA copolymer/silica nanocomposites, followed by HF etching. Thermogravimetric analysis of AN-MMAcopolymer/silica nanocomposltes snoweO mat me caroon ylelCl or copolymer was slgnuy oecreaseo as Silica parucle incorporated. N2 adsorption-desorption, scan electron microscopy （SEM） and transmission electron microscopy （TEM） were used to characterize the structure and morphology of the mesoporous carbon materials. Both SEM and

Development of Urease Immobilization Using Poly（acrylonitrile）/Chitosan Composite Materials

PANCHI （poly（acrylonitrile）/chitosan） composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of poly（acrylonitrile） and PANCHI membranes were determined by SEM analyses It was found that the membrane coated with 1.0% chitosan shows the maximum reduced pore size. The amounts of the functional groups and the degree of hydrophilicity of PANCHI composite membranes were determined. Urease was covalently immobilized onto all kinds of PANCHI membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity （92.96%） was measured for urease bound to PANCHI （1%） membranes. The basic characteristics of optimum conditions （pH and temperature）, heat inactivation and storage stability of immobilized urease were determined. Immobilization improved the thermal, pH and storage stability of the enzyme. The obtained results show that the poly（acrylonitrile）/chitosan composite materials are suitable for urease immobilization.

Evaluation of Impact Strength and Micro-Hardness of Denture Base Acrylic Resin （PMMA） Part Ⅱ

Poly （methyl methacrylate） is widely used as denture base material. During fabrication of a denture, the physical and mechanical properties are influenced by cure condition. Each cure cycle or fabrication technique is attempts to optimize the properties for a given application. The aim of this study was to compare two types of commercially available denture base materials （heat-cure and self-cure） in their mechanical properties. The samples were prepared according to the daily routine work for sample preparation in dental laboratories. After reaching dough stage the mix packed into dumbbell shaped of stainless steel mould and pressed in a hydraulic bench press for 25 mins at room temperature. For heat cure the polymerization cycle was carried out using water bath, while self cure was done at room temperature. The impact strength was evaluated using Charpy impact test. The hardness test was conducted using a calibrated Vickers hardness tester machine. The lowest impact strength was observed in self-cure denture base material （self cure material 6.2 kJ/m^2 while heat cure 12.69 kJ/m^2. It appears that the tendency of heat cure to fracture was lower than self-cure denture base materials. Heat cure denture base material has significantly higher hardness test values than self-cure denture base material. The observed VHN value of the heat-cure was 20.09 g/mm^2 while the self-cure value was 12.7 g/mm^2. This is may be due to the plasticizer effect of residual monomer which was higher in self curing material as reported in previous work. Generally, the heat cure material showed better properties compared to self cure material.

Biomimicking and evaluation of dragonfly wing morphology with polypropylene nanocomposites

Dragonfly hindwing inspired two different flapping wing morphologies are investigated for flexible flapping wing micro air vehicles(FWMAV)applications.The wing skin is developed using 1%functionalized carbon nanotubes reinforced polypropylene nanocomposites with carbon fiber epoxy composite strands as venation pattern.The resonance frequencies are the fundamental information for biomimicking and were calculated theoretically from stiffness data.Bending dominated first natural frequency was obtained from flexural stiffness data and found close to the flapping frequency of natural dragonfly hindwing.Twisting dominated second natural frequency was obtained from torsional stiffness,which revealed that the artificial wings can be fabricated thinner.The flapping frequency of artificial wings is unaffected by the twisting deformation.The bending and twisting dominated mode shapes are also studied using the digital image correlation(DIC)system.To verify the static and dynamic results,finite element simulations are performed that agree with experimental findings.It was found that the proposed flexible nanocomposite wing skin can control the bending and twisting dominated frequencies by tailoring the wing morphology without affecting the mode shapes of deformation.

Metal-film-assisted ultra-clean transfer of single-walled carbon nanotubes

Transfer printing of nanomaterials onto target substrates has been widely used in the fabrication of nanodevices, but it remains a challenge to fully avoid contamination introduced in the transfer process. Here we report a metal-film- assisted method to realize an ultra-clean transfer of single-walled carbon nanotubes （SWCNTs） mediated by poly（methyl methacrylate） （PMMA）. The amount of PMMA residue can be greatly reduced due to its strong physical adhesion to the metal film, leading to ultra-clean surfaces of both the SWCNTs and the substrates. This metal-film-assisted transfer method is efficient, nondestructive, and scalable. It is also suitable for the transfer of graphene and other nanostructures. Furthermore, the relatively low temperature employed allows this technique to be compatible with nanomaterial-based flexible electronics.

Electrospun MoO_2@NC nanofibers with excellent Li^+/Na^+ storage for dual applications

MoO_2@N-doped C nanofibers（MoO_2@NC NFs）were synthesized by electrospinning with polyacrylonitrile as carbon source.The in situ formed MoO_2nanocrystals are completely embedded in the carbon nanofibers,which can not only accelerate ion transition,but also act as a buffer to avoid the mechanical degradation of active material due to the volume changes during charge/discharge cycling.When used as the anode material for both Li/Na-ion batteries,the as-synthesized MoO_2@NC NFs displayed excellent Li~＋/Na~＋storage properties.As the anode for Li-ion battery,the MoO_2@NC NFs display a high discharge capacity of 930 mA h g^（-1）at a current density of 200 mA g^（-1）for 100 cycles,and 720 mA h g^（-1）at a current density of 1 A g^（-1）for 600 cycles.Moreover,the discharge capacity of 350 mA h g^（-1）could be realized at a current density of 100 mA g^（-1）for 200 cycles for Na-ion battery.