Influence of textile preforming binder on the thermal and rheological properties of the catalyzed cyclic butylene terephthalate oligomers

The influence of an epoxy resin textile preforming binder on the thermal and rheological properties of the catalyzed Cyclic Butylene Terephthalate (CBT) oligomers was studied for the manufacturing of textile reinforced pCBT composites with bindered textile preforms. Thermal and rheological investigations were conducted with Differential Scanning Calorimetry (DSC) and plate-plate rheometry, respectively. Significant influences on both non-isothermal und isothermal crystallization of in situ polymerized Cyclic Butylene Terephthalate (pCBT) were observed due to the presence of preforming binder. The crystallization temperature and the crystallinity of pCBT polymer during cooling are both found to decrease with increasing filling fraction of preforming binder. The isothermal polymerization and crystallization process was confirmed to be influenced in the aspect of the starting time of crystallization, the crystallization rate and the crystal structures due to the addition of preforming binder. Furthermore, the processing time was found to be prolonged by adding the preforming binder.     

Toughening effect of maleic anhydride grafted linear low density polyethylene on linear low density polyethylene

The blend of linear low density polyethylene (LLDPE) and maleic-anhydride grafted LLDPE with the grafting degree of 1.3% and the gel content of 27.0% (designated as LLDPE/MA-PE) was melt-compounded. Their thermal, rheological, and mechanical properties were studied. The crystallization temperature and crystallization rate of LLDPE/MA-PE blends increase due to the nucleation of MA-PE, their crystallinity is between those of LLDPE and MA-PE due to the balance between the nucleation of MA-PE and simultaneously produced more defects. The addition of MA-PE increases the apparent viscosity of blend melts, but the shear-sensitivity of blends provides them with melting processing. Interestingly, the lamellar crystallites induced by MA-PE decrease the tensile yielding strength of LLDPE/MA-PE blends. During the impact fracture, the formation of oriented crystalline lamellae parallel to the crack front and perpendicular to the crack flank, leads to the deformation and microstriations in LLDPE/MA-PE blends. Subsequently, toughness of LLDPE/MA-PE blends is improved.     

In situ and ex situ investigation on the annealing performance of the ZnO film grown by ion beam deposition

The effects of the post-annealing treatment on the properties of the ZnO thin films deposited by ion beam sputtering have been investigated. By using in situ X-ray diffraction technique, an overview of the crystallization behavior of the ZnO film during the annealing process was obtained. It was found that the whole process can be divided into three regions. The improvement of the film’s crystallinity performance mainly occurs within the annealing temperature ranging from 300 to 600 °C. Both in situ and ex situ XRD results show the shift of the ZnO (002) peak towards high angle with the increasing annealing temperature, which is attributed to the variation of the stress in the film. The stress is mainly caused by the intrinsic stress which is affected by the oxygen deficiency in the film. The oxygen deficiency is sensitive to the annealing ambient. The film annealed in the O₂ ambient has less oxygen deficiency and higher resistivity. All the ZnO films deposited on the glass substrates have an optical transmittance over 85% in the visible region. Our results show that the ZnO films deposited using ion beam sputtering exhibit good thermal stability and high performance after annealing.     

合成条件对煤／ZnMgAl—LDHs纳米复合材料的影响

以超细神府煤为模板,采用原位共沉淀法制备了煤／水滑石类化合物（Coal／LDHs）纳米复合材料,并探讨了模板剂用量、沉淀反应pH及晶化时间对形成产物的物相及组成的影响,用X射线衍射（XRD）、傅里叶红外变换红外光谱（FTIR）及扫描电镜（SEM）对产物进行了表征,结果表明,所得复合材料具有典型的层状结构特征,煤模板剂对锌镁铝金属离子的选择性吸附使得产物中锌元素含量显著提高,煤酸性官能团如羧基等与水滑石层板羟基产生强烈的氢键相互作用,复合材料为纳米片状包覆表面;随着神府煤模板剂用量的增加,晶化时间延长,复合材料结晶度下降,煤与水滑石层板相互作用增强,材料表面的纳米片状团聚度降低;pH=10时,复合材料结晶度最好。     

Re-crystallization of silicalite-1 crystals from a crystalline layered silicate using nanosized seeds

Crystallization of silicalite-1 guided by nanosized seeds has been carried out from a crystalline layered silicate. The crystallization process was investigated by crystallinity of silicalite-1 obtained by hydrothermal treatments of the seeds/crystalline layered silicate mixtures with H₂O/Si ratios of 2, 6, and 12, respectively, at 423 K. Time courses of the crystallinity revealed the improved crystallization rate: the crystallization with the seeds was completed for 24 h although it spent more than 48 h without the seeds. SEM observation of the products showed well-crystallized particles with a coffin-like shape reflecting the crystal growth of the seeds. The particles sizes were 2-4 μm for the products by the treatment with the H₂O/Si ratio of 6 and 12, although the size was < 2 μm for the product with the H₂O/Si ratio of 2, suggesting that less H₂O content brings about the limited growth. As a result, we have succeeded to control the crystallization process of silicalite-1 from the crystalline layered silicate by impregnation of the seeds.     

In situ 3-hexylthiophene polymerization onto surface of TiO<Subscript>2</Subscript> based hybrid solar cells

A novel configuration of hybrid solar cells fabricated using TiO₂ and in situ polymerization of poly(3-hexylthiophene), or P3HT, on the surface of TiO₂ is reported. Comparison of UV–Vis absorption and current/voltage (I/V) characteristics of devices with or without in situ polymerized P3HT layer were discussed, and the surface morphology of TiO₂/in situ polymerized P3HT film was investigated by AFM in the contact mode. The short-circuit current density and energy conversion efficiencies of device with in situ polymerized P3HT layer were higher by 6 times and 3 times compared to that of device without the in situ polymerized P3HT layer. By adding poly (ethylene dioxythiophene)-poly (styrene sulfonic acid)(PEDOT-PSS) layer under the top contact, device showed a short-circuit current density of 1.27 mA cm⁻², an open-circuit voltage of 0.52 V, a fill factor of 0.24, and a energy conversion efficiency of 0.16% at AM 1.5 solar illumination (100 mW cm⁻²).     

Reinforcing effect of organo-modified layered silicates in high-density polyethylene

This study focuses on the understanding of the reinforcing effect given by organo-modified layered silicates to a high-density polyethylene and the influence on the crystallization properties of this polymer. The addition of organo-modified clay to high-density polyethylene resulted in an evident increase in the tensile and flexural Young's modulus of the material with respect to unfilled polymer. The morphology, crystallinity, and thermo-oxidative stability of such nanocomposites were investigated using X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, and oxidation induction time test. The materials obtained show tactoid as well as intercalated and exfoliated structures with different dominant states depending on the loading level and process conditions. It was observed that organic ions not only change mixing behavior but also influence material properties, including the degree of crystallinity and the stability to the thermo-oxidative phenomena.     

SiO2/聚（3-羟基丁酸酯-co-4-羟基丁酸酯）薄膜研究

目的研究纳米SiO2对可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P34HB)包装膜结晶行为和力学性能的影响。方法采用溶液浇铸法制备SiO_2/P34HB纳米复合薄膜,利用红外光谱仪(FTIR)、扫描电镜(SEM)、正置热台显微镜(POM)、差示扫描量热仪(DSC)和万能力学试验机等研究纳米SiO_2对P34HB结构、结晶性和力学性能等的影响。结果纳米SiO_2在P34HB中起到异相成核的作用,SiO2/P34HB复合膜的结晶速率和结晶度得到明显改善。相比P34HB包装膜,当纳米SiO_2质量分数为2%时,SiO_2/P34HB复合膜的弹性模量和拉伸强度分别提高了72.7%和60.9%。结论获得了纳米SiO2改善可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)包装膜结晶度和力学性能的最佳掺杂比例参数。     

热定型温度对改性双向拉伸聚酯薄膜性能的影响

为研究热定型温度对改性双向拉伸聚酯(BOPET)薄膜性能的影响,对两种热定型温度的BOPET薄膜的结构、结晶度、热效应进行了测试和评估。研究结果表明:BOPET薄膜经不同温度热定型后,其化学组成未发生变化,但是其结晶状态发生了变化,热定型温度的提高会导致BOPET薄膜的结晶度降低;提高热定型温度对树脂T g及熔点影响不大,而随着热定型温度的提高,冷结晶峰起始温度及峰顶温度向高温方向移动,提高热定型温度有利于抑制BOPET的二次结晶能力。     

准分子激光引起的非晶硅薄膜晶化行为的研究

利用KrF准分子激光对非晶硅薄膜的表层进行了晶化.研究了激光能量密度和照射脉冲数对薄膜结晶度的影响,并对晶化后薄膜的形貌和结构进行了表征.结果表明:该非晶硅薄膜晶化阈值约为110 mJ/cm2,且不受照射脉冲数的影响;激光能量密度是影响薄膜结晶度的首要因素,但在较低的能量密度时,增加照射脉冲数也会显著的提高薄膜结晶度;结构及形貌表征发现,薄膜晶化层厚度约为400～500 nm,平均晶粒尺寸为30～50 nm.     

Study on the non-isothermal crystallization behaviors of PA6/silica nanocomposites prepared by the sol–gel process

A organic–inorganic PA6/partially functionalized silica hybrid nanocomposites was prepared by caprolactam polymerized and silica nanoparticles in situ gernerated through condensation of partially functionalized silicic acid, which was prepared through hydrolysis of tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTES), in one process. The non-isothermal crystallization behaviors of pure PA6, PA6/unfunctionalized silica (PA6S) and PA6/functionalized silica (PA6FS) hybrid materials were investigated by differential scanning calorimetry (DSC). Two methods, namely, the Avrami and the Mo, were applied to describe the crystallization process of these three materials. DSC results showed that the crystallization rates of PA6FS is faster than that of pure PA6 and PA6S at the same cooling rate, the nano-silica particles functionalized by GPS in hybrid material acted as more effective nucleation agents, and the crystallization rates of all these samples increased with the cooling rate increasing. XRD results indicated that the addition of functionalized nano-silica particles favored the formation of the γ crystalline form.     

PBS/氧化石墨烯复合薄膜的制备与性能

目的利用氧化石墨烯(GO)为填料制备聚丁二酸丁二醇酯(PBS)的增强复合薄膜材料。方法以生物可降解材料PBS为基体,以GO为纳米增强相,首先用双十二烷基二甲基溴化胺(DDAB)对GO进行修饰,进而通过溶液复合法制备PBS/GO复合薄膜,并对其力学性能、结晶熔融行为和热稳定性进行表征。结果力学性能测试表明,在GO质量分数为0.1%时,复合薄膜的拉伸强度和断裂伸长率较纯PBS分别提高了37%和25%,但是随着GO含量的继续增加,其拉伸强度和断裂伸长率都呈现出下降趋势;热行为分析表明,GO的加入使PBS的熔融温度和结晶温度均有所提高,结晶度有所下降,但GO对PBS的热稳定性并无明显影响。结论适量GO的加入有利于改善PBS生物降解材料的力学性能和结晶熔融行为。     

High thermal stability PS-<Emphasis Type="Italic">b</Emphasis>-PEO templated mesoporous titania film

For many advanced applications, high thermal stability above 400 °C remains as a challenge for the ordered mesoporous titania films. In this work, we attempt to increase the thermal stability of mesoporous structure in titania film crystallization via PS-b-PEO block copolymer templating route. This paper reports the highly crystallized mesoporous titania film on silicon substrate thermally stable at 600 °C. The photocatalytic activity of the titania mesoporous film was also shown to be twice of that templated by F127 for degradation of methylene blue (MB). The present results also indicate that at low crystallinity, photocatalytic activity is controlled primarily by crystal perfection rather that surface area.     

功能化碳纳米管的制备及功能化碳纳米管/尼龙6复合纤维

采用多聚磷酸(PPA)/P₂O₅弱酸体系, 通过傅克反应(Friedel-Crafts reaction)对多壁碳纳米管(MWCNTs)进行功能化改性, 加入己内酰胺后采用原位聚合法制备功能化碳纳米管(F-MWCNTs)/尼龙6(PA6)复合材料, 并熔融纺丝制备复合纤维。通过TEM、TG、DSC、SEM及力学性能测试对复合纤维进行表征。结果表明: 在MWCNTs表面成功地接枝了氨基, F-MWCNTs均匀地分散在PA6基体中, 没有发生团聚现象, 并且与基体具有很好的界面作用; F-MWCNTs的加入, 对复合纤维的熔融温度和结晶度影响不大, 结晶温度有所提高, 并明显提高了复合纤维的热稳定性; 随着F-MWCNTs的加入, 复合纤维的拉伸断裂强度和杨氏模量增加, 当F-MWCNTs质量分数为0.5%时, 拉伸断裂强度和杨氏模量达到最大, 比纯PA6纤维分别提高了45%和208%。     

Microcellular injection-molding of polylactide with chain-extender

The effects of adding an epoxy-based chain-extender (CE) on the properties of injection-molded solid and microcellular polylactide (PLA) were studied. PLA and PLA with 8 wt.% CE (PLA-CE) were melt-compounded using a twin-screw extruder. Solid and microcellular specimens were produced via a conventional and microcellular injection-molding process, respectively. Various characterization techniques including gel permeation chromatography, tensile testing and dynamic mechanical analysis, scanning electron microscopy and differential scanning calorimetry were applied to study the molecular weight, static and dynamic mechanical properties, cell morphology, and crystallization behavior, respectively. The addition of CE enhanced the molecular weight but decreased the crystallinity of PLA. The addition of CE also reduced the cell size and increased the cell density. Furthermore, the decomposition temperatures and several tensile properties, including specific strength, specific toughness, and strain-at-break of both solid and microcellular PLA specimens, increased with the addition of CE.     

Bidirectional Anions Gathering Strategy Afford Efficient Mixed Pb?Sn Perovskite Solar Cells

Mixed lead-tin (Pb Sn) perovskite solar cells (PSCs) possess low toxicity and adjustable bandgap for both single-junction and all-perovskite tandem solar cells. However, the performance of mixed Pb Sn PSCs still lags behind the theoretical efficiency. The uncontrollable crystallization and the resulting structural defect are important reasons. Here, the bidirectional anions gathering strategy (BAG) is reported by using Methylammonium acetate (MAAc) and Methylammonium thiocyanate (MASCN) as perovskite bulk additives, which Ac⁻ escapes from the perovskite film top surface while SCN⁻ gathers at the perovskite film bottom in the crystallization process. After the optoelectronic techniques, the bidirectional anions movement caused by the top-down gradient crystallization is demonstrated. The layer-by-layer crystallization can collect anions in the next layer and gather at the broader, enabling a controllable crystallization process, thus getting a high-quality perovskite film with better phase crystallinity and lower defect concentration. As a result, PSCs treated by the BAG strategy exhibit outstanding photovoltaic and electroluminescent performance with a champion efficiency of 22.14%. Additionally, it demonstrates excellent long-term stability, which retains ≈92.8% of its initial efficiency after 4000 h aging test in the N₂ glove box.     

不同成膜工艺对PCL结晶及微生物降解性能的影响

将压延成膜和溶剂成膜制备的聚ε-己内酯(PCL)膜放入降解液进行100d的生物降解,以研究不同成膜工艺对PCL降解性和降解前后结晶的影响。采用显微镜观察降解前后薄膜表面形态变化;通过广角X射线衍射法(WAXD)表征其降解前后结晶变化;利用凝胶渗透色谱(GPC)测定降解过程中PCL相对分子质量和分子量分布的变化。研究结果表明,溶剂成膜工艺可提高PCL亲水性,增大结晶尺寸,提高PCL降解性;而压延成膜工艺使膜表面致密,结晶尺寸减小,但对结晶形态和结晶度影响不大,降解后PCL晶形均未发生大的变化,结晶度有所下降。     

From two-dimensional metal-organic coordination networks to near-infrared luminescent PbS nanoparticle/layered polymer composite materials

Two-dimensional (2-D) layered metal-organic coordination (lead methacrylate (LDMA)) networks have been prepared in aqueous solution under mild conditions and their structure determined by single crystal diffraction. As the ligand used in our experiments is easily to polymerized, these metal-organic coordination layers are therefore employed as precursors to fabricate cross-linked polymer layered materials through γ-irradiated polymerization. The stabilities of the samples are significantly improved after γ-irradiation. To our knowledge, this is the first time that covalent bonded polymer layered structures have been fabricated without the assistance of added surfactant or template. Such layered polymer materials cannot only act as alternative to layered inorganic materials in some caustic environments, but also allows the generation of PbS nanoparticles (NPs) without aggregation in the polymer matrix. By exposing the polymer layer to H₂S gas at room temperature, uniform PbS nanoparticles with an average size of about 6 nm are generated in situ. In addition, the resulting PbS NPs exhibit near-infrared (NIR) luminescent properties, which suggests the composite materials may be useful as active optical elements at communication wavelengths from 1300 to 1550 nm. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. This article is published with open access at Springerlink.com     

Poly(lactic acid)/clay nanocomposites: effect of nature and content of clay on morphology,thermal and thermo-mechanical properties

Nanocomposites were prepared by melt blending Poly(lactic acid) with 5 and 7 wt% of an organically modified montmorillonite or an organically modified magnesium sodium fluoro-hectorite or unmodified sepiolite.All nanocomposites show a good level of clay dispersion into the polymer matrix as well as a considerable thermal and thermo-mechanical properties improvement. According to thermal analysis, the clays seem to act as nucleating agents inducing a higher degree of crystallinity of the polymer and rate of crystallization. Similar increases in the thermal stability of Poly(lactic acid) were obtained for all clays. Concerning layered silicate nanocomposites, it was found that the main influencing factors on the thermo-mechanical properties appear to be the aspect ratio and dispersion of clay nanoplatelets, rather than polymer/clay chemical compatibility. Needle like sepiolite shows thermo-mechanical improvements comparable to some layered silicates and an interesting ability to maintain high storage modulus values at increasing temperatures, due to its good dispersion within the polymer without the need of organic modifiers as instead necessary for layered clays used in this work.     

木粉/低熔点尼龙6复合材料的非等温结晶动力学

利用LiCl改性尼龙6 (PA6),并将其与木粉熔融共混制备了木粉/低熔点PA6复合材料,通过DSC法研究了木粉/低熔点PA6复合材料的非等温结晶动力学行为。结果表明,LiCl降低了PA6的熔点、结晶温度、结晶度和结晶速率,提高了PA6的结晶活化能。木粉是良好的成核剂,能够加快PA6的结晶速率,但却降低了其结晶度。通过Mo法分析木粉/低熔点PA6复合材料的非等温结晶动力学,结果表明,与纯PA6和木粉/PA6复合材料相比,低熔点PA6的F(T)值(表征聚合物结晶快慢参数)最大,LiCl提高了PA6在单位结晶时间内达到一定结晶度时所需的冷却速率,而木粉则与之相反。