玻璃纤维增强建筑用聚乙烯树脂复合材料的性能

采用剥离测试方法来表征制得的玻璃纤维增强建筑用聚乙烯树脂复合材料的界面黏结强度,并对其进行红外光谱、接触角、微观组织测试与分析。研究结果表明:采用浸润剂处理可以使玻璃表面生成新基团;浸润剂能够提高玻璃表面接触角,从而更易与树脂形成浸润状态,由此改善玻璃和树脂的界面结合状态,实现界面黏结特性的显著优化。在剥离测试中发现经浸润剂处理后,玻璃可以和树脂之间形成更强的界面结合作用;树脂从玻璃表面发生剥离之后,形成了光滑的玻璃片,同时还有部分纵横交错的划痕。     

Adhesion and interfacial characterization of biomimetically texturized lithium disilicate

Lithium disilicate glass-ceramic (LS2) can be biomimetically textured by crystal orientation, mimicking the microstructure of dental enamel and inducing anisotropic mechanical responses to crack growth. The deliberate texturization of LS2 plays to the clinical advantage of reinforcing weak sites of typical fracture initiation in dental prosthetic constructs. Similar to enamel, adhesion of biomimetically textured LS2 could also show anisotropic behavior. Therefore, tensile bond strength (TBS) before and after thermocycling (TC) and interfacial characterization of biomimetically textured LS2 (parallel (PAR) or perpendicular (PER) crystal orientation) after different pre-treatment modes (hydrofluoric acid etching (HFE), grit blasting (GBL) and self-etching glass-ceramic primer (SGP)) were investigated. TC reduced significantly TBS for all specimens except for GBL. Biomimetic textured LS2 after HFE showed anisotropic behavior regarding adhesion. Crystal orientation reduced TBS for the PER HFE specimens after TC significantly. In general, the TBS of HFE specimens was still higher or not significantly lower compared to other pre-treatment modes like GBL or SGP. For the GBL and SGP specimens, crystal orientation had no influence on TBS and interfacial characteristics. In contrast HFE specimens showed different interfacial characteristics depending if they were PAR or PER texturized. Based on these findings, HFE of biomimetic textured LS2 can be recommended. For bonding, the PAR orientation is recommended as its adhesion potential is less prone to degrade.     

基于静电喷雾法萝卜硫素微胶囊的制备与表征

使用静电喷雾法制备不同壁材的萝卜硫素（sulforaphane，SF）微胶囊，通过表征微胶囊表面形貌、分子间相互作用、热行为、体外释放情况以及在高温下的贮存稳定性，研究食品级聚合物对SF的微胶囊化作用，从而筛选出适合静电喷雾包封SF的壁材。结果表明，微胶囊平均粒径在427.80～1 857.04 nm之间，呈球状，表面光滑。相比壳聚糖，玉米醇溶蛋白（Zein）和明胶（gelatin，Gel）是更有效的SF递送载体，Zein-SF、Gel-SF的包封率分别为（95.83±2.37）%、（95.11±2.82）%。傅里叶变换红外光谱确认了SF微胶囊中SF的存在；热重分析结果显示SF微胶囊在300 ℃的高温下才大量降解，有较高的热稳定性。SF微胶囊在模拟胃肠液和食物基质的最终释放率在80%～90%之间，具有良好的胃肠溶解和释放性能；同时，微胶囊化处理后的SF耐热性显著提高。本研究结果有助于进一步开发SF递送载体，促进其产业化应用。     

Effect of moisture and filler content on the structural,thermal and dielectric properties of polyamide‐6/boehmite alumina nanocomposites

Polyamide‐6 (PA‐6)/boehmite alumina (BA) nanocomposites were prepared via direct melt compounding. Structural, thermal and dielectric properties of ‘as‐received’ (including moisture) and ‘dried’ (thermally treated) specimens were examined. The BA nanofiller was homogeneously dispersed in the PA‐6 matrix. XRD and FTIR revealed that crystallization of PA‐6 in the γ phase was favoured over α phase with increasing BA content. The crystallinity index (CI) and the percentage of α and γ phases were also evaluated. Dried specimens exhibited a lower CI than as‐received specimens while the CI decreased with the addition of filler. Broadband dielectric spectroscopy revealed the presence of γ, β and α relaxations, the Maxwell–Wagner–Sillars effect and the contribution of conductivity relaxation in the as‐received samples. The drying procedure unmasked a double feature of both β and α modes. The results of the complementary techniques were analysed and the effects of moisture and/or the incorporation of BA nanofiller on the microstructure of the PA‐6 matrix are disclosed. © 2019 Society of Chemical Industry     

Microstructure-abrasive wear correlation of in situ ZA27/TiC composites

Abrasive wear is a complex surface degradation process driven by various factors such as microstructure, the mechanical properties of the target material, the abrasive, loading conditions, and the surrounding environment. In this study, in situ TiC reinforced Zinc Aluminum alloy composites were prepared through a liquid metallurgy route and the synergistic effect of applied load, sliding speed, abrasive grit size and TiC content on the high-stress abrasive wear response were investigated. The test materials' wear response was established by characterising wear surfaces, sub-surfaces, debris particles, and an abrasive medium. The study suggests that the wear resistance of the specimens decreases with an increase in the applied load, and the composite reinforced with 10 wt % of TiC shows superior wear behaviour among all the test materials. The study also points out that the ZA-27 alloy reinforced with in situ TiC can be a suitable replacement of the conventionally used materials for automotive applications.     

Characterization and selection of suitable grades of lactose as functional fillers for capsule filling: part 1

The purpose of this work is to characterize thermal, physical and mechanical properties of different grades of lactose and better understand the relationships between these properties and capsule filling performance. Eight grades of commercially available lactose were evaluated: Pharmatose 110?M, 125?M, 150?M, 200?M, 350?M (α-lactose monohydrate), AL (anhydrous lactose containing ～80% β-AL), DCL11 (spray dried α-lactose monohydrate containing ～15% amorphous lactose) and DCL15 (granulated α-lactose monohydrate containing ～12% β-AL). In this study, different lactose grades were characterized by thermal, solid state, physical and mechanical properties and later evaluated using principal component analysis (PCA) to assess the inter-relationships among some of these properties. The lactose grades were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), moisture sorption/desorption isotherms, particle size distribution; the flow was characterized by Carr Index (CI), critical orifice diameter (COD) and angle of friction. Plug mechanical strength was estimated from its diametric crushing strength. The first and second principal components (PC) captured 47.6% and 27.4% of variation in the physical and mechanical property data, respectively. The PCA plot grouped together 110?M, AL, DCL11 and DCL15 on the one side of plot which possessed superior properties for capsule formulation and these grades were selected for future formulation development studies (part II of this work).     

Water Content Determinations for Peat and Other Organic Soils Using the Oven-Drying Method

There has been much debate in the literature over the past 60 years regarding an appropriate oven-drying temperature for water content determinations in peat and other organic soils. For inorganic soils, the water content is usually based on the equilibrium dry mass corresponding to drying temperatures in the range 100–110°C. However, for peat and other organic soils, several researchers have recommended lower drying temperatures in the range 60–90°C in an attempt to prevent possible charring, oxidation, and/or vaporization of substances other than pore water. However, all of the relevant water is not fully evaporated at too low a temperature, and because specimen dry mass is a function of drying temperature, the resulting water content values are lower than those determined for the temperature range 100–110°C. Experimental data reported in this article show that oven drying of peat and other organic soils at 100–110°C using either gravity–convection or forced-draft ovens is acceptable for routine water content determinations. Because a standardized oven temperature is desirable when correlating water content with other material properties, it is recommended that oven drying of peat and other organic soils be performed over temperature ranges of either 105–110°C or 105 ± 5°C, in line with standardized ranges for inorganic soils.     

A new strength test for ceramic cylinders—The Notched Roller Test

A new tensile strength test for ceramic rollers (cylinders) is presented, following the idea of the previously published and since that time standardized notched ball test. The specimen is prepared by cutting a long narrow notch along the symmetry plane of the roller, perpendicular to the end faces. By applying compressive forces perpendicular to the notch, tensile stresses are induced in the outer surface region of the roller opposite to the notch, mainly pointing in tangential direction with respect to the roller axis. The stress amplitude is proportional to the applied force and depends also on the test geometry and the Poisson’ ratio, which has been analyzed carefully with FE methods.Strength tests have been performed on two different qualities of commercial silicon nitride rollers of 10 mm diameter and length. According to their specification a significant difference in the strength has been obtained.