硼吸附用聚丙纤维接枝苯乙烯离子交换纤维

研制了一种应用于硼吸附的苯乙烯系离子交换纤维,该离子交换纤维是采用市售聚丙烯纤维接枝苯乙烯的复合纤维产品为骨架,通过氯甲基化,然后导入N-甲基葡萄糖胺基进行氨化反应,从而得到具有硼选择性吸附的离子交换纤维。这种选择性离子交换纤维不受大量共存盐类的影响,能只对硼酸选择捕捉,同时具有较高的比表面积,可代替颗粒状离子交换树脂用于硼的吸附,因此具有很高的实用价值。

聚丙烯纤维长度对水工混凝土抗冻性能的影响研究

在混凝土中掺加一定量的聚丙烯纤维,可以有效提升其力学和耐久性能,具有重要的工程意义。文章通过室内试验的方式,探讨了聚丙烯纤维长度对混凝土抗冻性能的影响。试验结果显示,纤维长度对混凝土的抗冻性存在显著影响。根据试验结果,建议在水工混凝土制作过程中采用长度20 mm左右的聚丙烯纤维。

熔喷聚丙烯纤维非织造布生产工艺参数对其性能的影响

本文研究了用毛细管喷头以不同的螺杆挤出速度、接收距离等工艺参数,对熔融指数为12克/10分的熔喷聚丙烯超细纤维非织造布的断裂强度、断裂伸长、撕破强力、顶破强力、弯曲特性、过滤性能及纤维直径进行定量分析。文章还讨论了驻极电介质对空气过滤性能的影响。

改性聚丙烯纤维水泥基复合材料力学性能研究

研究了不同改性聚丙烯纤维水泥基复合材料的力学性能,结果表明 ,用二甲苯进行物理表面改性的聚丙烯纤维掺和硅烷偶联剂改性的聚丙烯纤维能有效提高水泥砂浆的抗折强度和抗压强度 ,有广泛的应用前景。

聚丙交脂-乙交酯纤维的温压成形

通过溶液沉析纺丝法制备聚丙交酯乙交酯(PLGA)纤维,观察纤维的形貌并对其进行XRD和SEM表征。采用纤维温压成形法控制压力和温度得到条形的PLGA材料结合试样断口分析,研究成型压力与温度对PLGA材料的力学性能的影响。研究结果表明:非晶多孔结构的PLGA纤维可通过溶液沉析纺丝的方法获得,其孔径为0.1～1.0μm;压制压力和压制温度对材料的力学性能影响较大,材料的抗弯强度、剪切强度和抗弯模量均随着温度和压力的增大而先增大后降低;在压制压力为105MPa,压制温度为160℃时,试样的力学性能比较理想,此时,其抗弯强度可达到187.3MPa,剪切强度达到100.1MPa,抗弯模量达到2.5GPa,可望作为非承重部位骨折愈合内固定材料。

水利工程建设中聚丙稀纤维混凝土的应用

混凝土是一种脆性建筑材料,根据工程需要,在混凝土中掺入聚丙纤维,可以增强混凝土的抗渗、抗裂、抗折、抗冲击的性能,提高混凝土的耐久性。更适于在水利工程建设施工方面的应用。

钢-聚丙烯混杂纤维混凝土基本力学性能综述

钢-聚丙烯混杂纤维混凝土(SPFRC)以其在提高强度、抗裂、抗劈裂和提高韧性方面的优异的力学性能而被大家了解。近年来,由于人们对建筑多样化的要求,对于SPFRC的研究也越来越多地被开展起来。而其中大多数也是关于基本力学性能的研究。已有的研究结果显示,SPFRC的力学性能在某些程度上会随着纤维体积率的增加而增加。对于该混凝土的破坏方式和抗劈裂方面也有研究,但现阶段对于该混凝土的各方面研究仍处于不系统、不完善的阶段。对于多种因素作用下的SPFRC的耐久性模型还需要更进一步探讨和研究。

纺丝油剂的一些新认识——卫生用热粘非织造布生产中的丙纶纤维油剂

如果在丙纶细旦丝凝固后不久上油,就可以生产出用于加工卫生用途的热结合非织造布的丙纶细旦丝短纤维(所有的合成纤维都是如此)。纺丝油剂降低了运动纤维与固体的摩擦,使静止纤维间建立合适的摩擦,

医用生物材料——聚乙丙交酯PGLA(90/10)聚合过程的研究

通过连续聚合的方法,合成了乙交酯和L-丙交酯的共聚物PGLA(90/10),研究了停留时间对聚合物特性粘数和单体转化率的影响;应用IR、1H-NMR、DSC、TG、毛细管流变仪等,对聚合物的结构、热性能、流变性能等进行了表征。

Removal of manganese from waste water by complexation-ultrafiltration using copolymer of maleic acid and acrylic acid

Copolymer of maleic acid and acrylic acid （PMA-100）, combining with polyvinyl butyral （PVB） ultrafiltration membrane was used for the removal of Mn（II） from waste water by complexation-ultrafiltration. The carboxylic group content of PMA-100 and the rate of complexation reaction were measured. Effects of the mass ratio of PMA-100 to Mn（II） （n）, pH, background electrolyte, etc on the rejection rate （R） and permeate flux （J） were investigated. The results show that carboxylic group content of PMA-100 is 9.5 mmol/g. The complexation of Mn（II） with PMA-100 is rapid and completed within 5 min at pH 6.0. Both R and J increase with pH increasing in the range of 2.5-7.0, and R increases with the increase of n at pH 6.0 while J is little affected. The background electrolyte leads to the decrease of R, and CaCl2 has much greater effect on R than NaCl at the same ionic strength.

Fracture Properties of Cement Composites Reinforced with Steel Polypropylene Hybrid Fibres

Polypropylene fibres and three sizes of steel fibres reinforced concrete are discussed. The total fibres content ranges from 0 4%-0 95% by volume of concrete. A four point bending test is adopted on the notched prisms with the size of 100?mm×100?mm×500?mm to investigate the effect of hybrid fibres on crack arresting. The research results show that there is a positive synergy effect between large steel fibres and polypropylene fibres on the load bearing capacity in the small displacement range. But this synergy effect disappears in the large displacement range. The large and strong steel fibre is better than soft polypropylene fibre and small steel fibre in the aspect of energy absorption capacity in the large displacement range. The static usage limitation for the hybrid fibres concrete with “wide peak' or “multi peaks' load CMOD pattern should be carefully selected. The ultimate load bearing capacity and the crack width or CMOD at this load level should be jointly considered.

Effect of polypropylene fiber and coarse aggregate on the ductility and fluidity of cemented tailings backfill

Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.

Strength characteristics of modified polypropylene fiber and cement-reinforced loess

The reinforcement and stabilization of loess soil are duscussed by using fibers as the reinforcement and cement as the stabilization materials.To study the strength characteristics of loess soil reinforced by modified polypropylene(MPP) fiber and cement,samples were prepared with six different fiber contents,three different cement contents,three different curing periods and three kinds of fiber length.The samples were tested under submergence and non-submergence conditions for the unconfined compressive strength(UCS),the splitting tensile strength and the compressive resilient modulus.The results indicated that combined reinforcement by PP fiber and cement could significantly improve the early strength of loess to 3.65–5.99 MPa in three days.With an increase in cement content,the specimens exhibited brittle fracture.However,the addition of fibers gradually modified the mode of fracture from brittle to ductile to plastic.The optimal dosage of fiber to reinforce loess was in the range of 0.3%–0.45% and the optimum fiber length was 12 mm,for which the unconfined compressive strength and tensile strength reached their maxima.Based on the analysis of failure properties,cement-reinforced loess specimens were susceptible to brittle damage under pressure,and the effect of modified polypropylene fiber as the connecting "bridge" could help the specimens achieve a satisfactory level of ductility when under pressure.

Tensile properties of strain-hardening cementitious composites containing polyvinyl-alcohol fibers hybridized with polypropylene fibers

Partially replacing polyvinyl-alcohol(PVA)fibers with polypropylene(PP)fibers in strain-hardening cementitious composites(fiber hybridization)modify certain mechanical properties of these materials.The hybridization based on the introduction of low-modulus hydrophobic polypropylene fibers improves the ductility and the strain-hardening behavior of the cementitious composites containing polyvinyl-alcohol fibers of different types(PVA-SHCC).Pull-out tests indicate that adding PP fibers increases the energy capacity of the hybrid composite with respect to the material containing only PVA fibers under tensile loading,and PP-fiber geometry(i.e.,section shape and length)is a key factor in enhancing the strain capacity.

Effect of Plasma Etching on Wicking Property of Polypropylene Fiber

Plasma etching technology is used to treat Polypropylene fiber with different fineness. The result shows that the plasma etching treatment is useful to improve the wicking property of polypropylene, although too much time of treatment may be converse to the wicking property. A surface roughness theory is applied to explain the reason why the plasma can improve the wicking property. In this experiment, fibers with different treating time under certain voltage(180 V) and pressure(0.1 mm Hg)are used as experimental sample.

Adsorption characteristics of carbon tetrachloride from aqueous solution onto polyacrylonitrile-based activated carbon fiber

The isotherm,mechanism and kinetics of carbon tetrachloride(CT) adsorption by polyacrylonitrile-based activated carbon fiber(PAN-ACF) were investigated in batch reactors and a continuous flow reactor,and the regeneration of PAN-ACF was also studied.Freundlich and Dubinin-Radushkevich(D-R) adsorption equations can well describe the adsorption isotherm.CT is mainly adsorbed on the exterior surface of PAN-ACF with low boundary layer effect and rate-controlling step of intra-particle diffusion.The adsorption dynamics in the batch reactor well fits with the pseudo-first-order model,and the breakthrough curves in the continuous flow reactor can be well described by the Yoon-Nelson model.The ACF can be recycled through thermal regeneration,whereas the adsorption capacity decreases from 7.87 to 4.98 mg/g after the fourth regeneration.78%-94%of CT can be removed from the wastewater of a fluorine chemical plant on a pilot scale,which confirms the efficacy of ACF under industrial conditions.The results indicate that PAN-ACF is applicable to CT removal from wastewater.

Catalytic graphitization of polyacrylonitrile(PAN)-based carbon fibers with Fe-Cr_2O_3 composite coating

The process of electrodepositing Fe-Cr2O3 composite coating on polyacrylonitrile （PAN）-based carbon fibers and its catalytic graphitization were studied. Carbon fibers with and without electrodeposited Fe-Cr2O3 composite coating were heat treated at different temperatures and the structural changes were characterized by XRD, Raman spectroscopy and SEM. The results indicate that Fe-Cr2O3 composite coating exhibits a significant catalytic effect on graphitization of carbon fibers at low temperatures. When the Fe-Cr2O3-coated carbon fibers were heat treated at 1 300℃ the interlayer spacing （doo2） and ratio of relative peak area （AD/AG） reach 3.364/k and 0.34, respectively. Whereas, the extent of graphitization of pristine carbon fibers is comparatively low even after heat treatment at 2 800℃ and the values of doo2 and AD/AG are 3.414 A and 0.68, respectively. The extent of graphitization of carbon fibers increases not only with the increase of the catalyst gross but also the Cr2O3 content in Fe-Cr2O3 coating. The catalytic effect of Fe-Cr2O3 composite coating accords with the dissolution-precipitation mechanism.

Catalytic graphitization of Mo-B-doped polyacrylonitrile(PAN)-based carbon fibers

A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.

胀紧式锥套联接的结构和计算

对引进设备所带胀紧式锥套联接（应用于风机传动部分）进行了改造，介绍了其结构和计算。

Application of modified polypropylene （crude） fibers concrete to strengthen the support structures in deep mine roadway

The an thors developed a new composite cement base material by mixing the high tenacity polypropylene （coarse） fiber in plain cement base for the cement-layer-spray technology. By studying the key parameters of the fiber dosage, the spray layer thickness, and the fiber reinforced concrete injection time, etc. It is found that the ideal volume ratio of polypropylene （crude） fiber is 0.8% （V/V）, and the secondary lining fiber concrete spraying should start when the shrinkage rate is lower than 0.5 mm/d, and the optimal thickness of shotcrete is 120 mm. The supporting effects and the economic benefits were studied using a real project practice, and the result obtained can be a good reference for practical applications of this new supporting material in the future.