AgNPs/TPU导电纤维的制备及性能研究

以热塑性聚氨酯(TPU)为弹性纤维基体，三氟乙酸银(C₂AgF₃O₂)为导电银纳米粒子(AgNPs)前驱体，水合肼为还原剂，采用湿法纺丝工艺、原位还原技术及热处理制备AgNPs/TPU导电纤维，研究了水合肼浓度、还原时间、C₂AgF₃O₂含量、热处理对纤维导电性能的影响，并对其微观形貌、化学组成、力学性能、拉伸电阻敏感性进行表征。结果表明：在C₂AgF₃O₂/TPU质量比为1.5：1.0,水合肼质量分数为15%,还原时间为20 min, 120℃热处理30 min的条件下得到的AgNPs/TPU导电纤维具有最佳的导电性能，电导率可达108.9 S/cm; AgNPs/TPU导电纤维微观上呈中空多孔结构，纤维表面被AgNPs均匀覆盖；AgNPs/TPU导电纤维的力学性能相比纯TPU纤维有所降低，断裂伸长率为484%,断裂强度为0.15 cN/dtex;该纤维可在0～70%的应变范围内表现出较为...     

高弹性MXene/TPU纳米纤维纱线的制备及其应变传感性能

采用静电纺丝技术制备了热塑性聚氨酯弹性体(TPU)纳米纤维膜,并通过"Biscrolling"的方法制备高弹性过渡金属碳化物/氮化物(Ti_3C_2T_x MXene)改性TPU纳米纤维纱线。通过SEM、电阻测试、传感性能测试等对复合纳米纤维纱线进行结构和性能表征。结果显示,随着MXene负载量的增加,复合纱线的强度先增加后降低,断裂伸长率可达459%以上,展现出优异的弹性和弹性回复性;MXene片可在纳米纤维纱线表面及内部形成连续导电薄膜,赋予复合纱线较好的导电性[电阻(76±16)?/cm]。纱线的应变传感性能测试表明,MXene/TPU纳米纤维纱线的传感系数可高达477.86,线性度高达0.995,高于绝大多数文献报道的纱线传感器,并且在监测人体的各种运动状态上展现出较好的应变传感性能。     

高弹性MXene/TPU纳米纤维纱线的制备及其应变传感性能

采用静电纺丝技术制备了热塑性聚氨酯弹性体(TPU)纳米纤维膜,并通过“Biscrolling”的方法制备高弹性过渡金属碳化物/氮化物（Ti3C2Tx MXene）改性TPU纳米纤维纱线。通过SEM、电阻测试、传感性能测试等对复合纳米纤维纱线进行结构和性能表征。结果显示,随着MXene负载量增加,复合纱线的强度先增加后降低,断裂伸长率可高达459%以上,展现出优异的弹性和弹性回复性;MXene片可在纳米纤维纱线表面及内部形成连续导电薄膜,赋予复合纱线较好的导电性（电阻76 Ω/cm）。纱线的应变传感性能测定实验表明,MXene/TPU纳米纤维纱线的传感系数可高达477.86,线性度高达0.995,高于绝大多数文献报道的纱线传感器,并且可以监测人体的各种运动状态,展现出较好的应变传感性能,在智能可穿戴领域展现出广泛的应用前景。     

静电纺丝法制备RGO/PU纳米复合纤维的研究

采用改进Hummer法制备了氧化石墨烯,并由氧化石墨烯制备了还原氧化石墨烯(RGO),将其添加到热塑性聚氨酯(PU)纺丝液中,用静电纺丝法制备了RGO/PU纳米复合纤维。讨论了纺丝电压对纤维的影响,考察了复合纤维膜的形貌、导电性能和力学性能。结果表明,纺丝电压为23~28 k V时有明显的泰勒锥;在PU中添加质量分数为0.50%的RGO可以明显提高复合纤维的导电性能;加入RGO后PU纤维拉伸强度和断裂伸长率提升明显。     

PVA/PANI导电复合纤维的制备

以聚合度2000的聚乙烯醇(PYA)为原料,采用干湿法凝胶纺丝制备PVA初生纤维,经拉伸、热定型后,在苯胺(ANI)溶液中浸渍聚合制备PVA/PANI导电纤维,研究了导电纤维的结构与性能。结果表明:采用干湿法制备的PVA初生纤维在常温下拉伸2倍,经ANI溶液浸渍聚合,得到的PVA/PANI导电纤维的体积电阻率达34Ω·cm,该导电纤维直接热定型后断裂强度达2.8 cN/dtex。     

基于夹心结构的碳纳米管/石墨烯复合柔性导电纤维的制备及其应用

具有较大检测区域的纤维状柔性导电材料是可穿戴电子产品和电子纺织品等多种柔性器件的重要组成部分。通过在氨纶复丝表面涂覆碳纳米管(CNT)/RGO导电层,继而在导电层外部涂覆弹性聚氨酯(TPU)保护层来制备夹心结构的高度可拉伸和高灵敏度的柔性导电纤维。1D CNT和2D RGO组成的多维导电网络使纤维在具有较大可拉伸性的同时又拥有较大的相对电阻变化(ΔR/R0),将其用作传感器可用工作范围达465%(GF为215. 0)。在与皮肤连接的可穿戴设备领域中具有广阔的应用前景。     

热塑性聚氨酯/碳纳米管湿纺导电纳米复合纤维的应变响应行为研究

采用湿法纺丝工艺制备出了碳纳米管(CNTs,质量分数为10%)/热塑性聚氨酯(TPU)导电纳米复合纤维。该纤维具备良好的电导率(0.64 S/m),高的强度(9.81 MPa)和高的断裂伸长率(487%)。纤维的电阻-应变响应范围为0~325%,其相对电阻(Δ_(R/R0))在该范围内分3个阶段呈指数增长。纤维的电阻-应变循环响应结果出现了肩峰和初始下降的现象,其灵敏度随应变的增大而增大,并且具备优异的耐久性。因此,TPU/CNTs导电纳米复合纤维在柔性应变传感器的应用方面具有很大的潜力。     

静电纺聚氨酯纳米纤维膜的制备及其性能研究

静电纺丝技术是制备纳米纤维膜的一种比较简单而且常用的技术。对静电纺丝技术制备聚氨酯(TPU)纳米纤维膜的最佳纺丝条件进行探索。此外,对制备的TPU纳米纤维膜进行了力学性能和介电性能的表征。结果表明,在纺丝液质量分数为12%、电压20 V、接收距离15 cm、THF与DMF的体积比为5∶1的条件下,制备的TPU纳米纤维膜表面无珠粒、纤维直径均匀,纺丝效果最佳。与纯TPU薄膜进行性能对比,TPU纳米纤维膜的断裂伸长率和拉伸强度远低于纯TPU薄膜,前者的介电常数比后者略低,但是前者的弹性模量低于后者。制备的TPU纳米纤维膜可以应用于气体过滤领域。     

软硬链段添加碳纳米管/炭黑对聚氨酯纳米纤维性能的影响

以聚丙二醇(PPG 2000)和二苯基甲烷二异氰酸酯(MDI-50)为原料,利用预聚法合成聚氨酯(PU)。在预聚过程中加入碳纳米管(CNT),合成碳纳米管/聚氨酯(CNT/PU);在扩链过程中加入炭黑(CB),合成炭黑/聚氨酯(CB/PU)。结合静电纺丝制备CNT/PU、CB/PU纳米纤维。采用SEM、TEM、FTIR、DSC、XRD对两种纳米纤维的结构进行了表征,对纳米纤维膜的电性能、力学性能及传感性能进行了测试。结果表明,由于CNT/CB在聚氨酯软硬链段的选择性嵌入,聚氨酯纳米纤维的微相分离程度分别增大/减小;相对纯PU纳米纤维膜,CNT/PU纳米纤维膜的断裂伸长率降低,CB/PU纳米纤维膜的断裂强度提高。导电填料(CNT、CB)的含量以聚氨酯的质量(PPG 2000、MDI-50和无水乙二胺的总质量)为基准,当CNT的含量为6.0%时,CNT/PU纤维膜的电阻率为1.22Ω·m,传感系数GF为45.64(拉伸应变在80%～120%);当CB含量为12.5%时,CB/PU纤维膜的电阻率为0.14Ω·m,传感系数GF为167.43(拉伸应变在80%～120%)。     

HPNGO/TPU复合纳米纤维的制备及其结构与性能研究

以N,N-二甲基甲酰胺(DMF)为溶剂、超支化聚酰胺修饰的氧化石墨烯(HPNGO)和热塑性聚氨酯(TPU)为原料,采用静电纺丝法制备了HPNGO/TPU复合纳米纤维。通过扫描电子显微镜、傅里叶变换红外光谱仪和动态力学分析仪研究了不同添加量的HPNGO对HPNGO/TPU复合纳米纤维的形貌、结构及性能的影响。结果表明:HPNGO/TPU复合纳米纤维直径与HPNGO的添加量成反比关系,纤维拉伸强度和初始模量与HPNGO的添加量成正比关系;当添加HPNGO质量分数(相对TPU)为3%时,HPNGO/TPU复合纳米纤维直径最小,平均直径为0.17μm,拉伸强度和初始模量最大,分别为3.884,0.193 MPa,断裂伸长率最小为170.2%;HPNGO的加入对TPU的分子结构无影响,二者之间为物理复合。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。