纳米SiO2改性对聚丙烯薄膜力学性能和阻隔性能的影响

为了改变聚丙烯薄膜的物理力学性能及阻隔性能,研制了一种自制的纳米SiO2改性助剂,通过与聚丙烯树脂熔融共混,吹制出聚丙烯/纳米SiO2复合薄膜,并对其拉伸性能、穿刺性能、摩擦系数、剥离强度等物理力学性能以及透氧、透湿等阻隔性能进行了测试。研究结果表明,当纳米SiO2的添加量为0.061%时,改性聚丙烯复合薄膜的拉伸性能及剥离强度有较大提高,穿刺性能、摩擦系数降低,同时,随着纳米SiO2添加量的增加,改性聚丙烯复合材料对水蒸气及氧气的阻隔性能显著增强。     

纳米结晶纤维素的常见制备方法及其改性应用

纳米结晶纤维素作为一种天然、可再生、无污染的高分子材料,其突出的理化性能和可生物降解性等在功能材料领域有着广阔的应用前景。对于纳米结晶纤维素的相关研究主要集中在制备、表面改性和应用方面,本文从上述三个方面综述了纳米结晶纤维素的研究现状,并对其进一步的研究趋势和发展方向进行了展望。     

Impact properties of thermoplastic composites

The excellent properties exhibited by thermoplastic composites at much reduced weight have attracted attention in the development of products in different sectors. Thermoplastic (TP) composites, because of their distinctive properties as well as ease of manufacturing, have emerged as a competitor against the conventional thermoset resin-based composites. Depending on the application, these composites may undergo impact events at various velocities and often fail in many complex modes. Hence, the development of TP composites having high energy-dissipation at (the desired) much-reduced weight has become a challenging task, but it is a problem which may be alleviated through the appropriate selection of materials and fabrication processes. Furthermore, fibre surface modification has been shown to increase fibre-matrix interfacial adhesion, which can lead to improved impact resistance. Textile preforms are helpful in acting as a structural backbone in the composites since they offer a relatively free hand to the composite designer to tailor its properties to suit a specific application. Additionally, hybrid textile composite structures may help in achieving the desired properties at much lower weight.

Simulation software can play a significant role in the evaluation of composites without damaging physical samples. Once the simulation result has been validated with actual experimental results, it should be possible to predict the test outcomes for different composites, with different characteristics, at different energy levels without conducting further physical tests. Various numerical models have been developed which have to be incorporated into these software tools for better prediction of the result.

In the current issue of Textile Progress, the effects of various materials and test parameters on impact behaviour are critically analyzed. The effect of incorporating high-performance fibres and natural fibres or their hybrid combination on the impact properties of TP composites are also discussed and the essential properties of TP polymers are briefly explained. The effects of fibre and matrix hybridization, environmental factors, various textile preform structures and fibre surface modification treatments on the impact properties of thermoplastic composites are examined in detail. Various numerical models used for impact analysis are discussed and the potential applications of TP composites in automobile, aerospace and medical sectors are highlighted.     

Use of low‐level plasma for enhancing the shrink resistance of wool fabric treated with a silicone polymer

This study examines the effects of an atmospheric pressure plasma (APP) pre‐treatment on the shrink resistance of wool fabric treated subsequently, by the pad/dry method, with an aqueous emulsion of the amino‐functional polydimethylsiloxane, SM 8709. Optimal shrink resistance (with no impairment of fabric handle) was obtained after a low‐level plasma treatment (1–3 s exposure time), using 5% of the polymer emulsion. Higher levels of silicone polymer could be used to achieve shrink resistance in the absence of a plasma pre‐treatment, but the fabric handle would be adversely affected. X‐ray photoelectron spectroscopy (XPS) studies showed that the bulk of the covalently bound surface lipid layer was removed after a plasma exposure time of 30 s. For treatment times of 3 s or less, however, the removal was incomplete, suggesting that optimum shrink resistance (after treatment with the silicone polymer) was associated with the modification of the surface layer rather than its complete destruction. Scanning electron micrographs (SEMs) revealed that the plasma pre‐treatment did not lead to any physical modifications (such as smoothening of the scale edges), even for long exposure times, and had no significant impact on the extent or nature of the inter‐fibre bonding of the polymer. Confocal microscopy showed uniform spread of polymer on single fibres. It is concluded that the main impact of the plasma pre‐treatment was to enhance the distribution of polymer both on and between fibres and to improve adhesion of polymer to the fibre.     

Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans (Phaseolus vulgaris L.)

Flavonoids and saponins from common beans have been widely studied due to their bioactivity. This research evaluated the effect of germination of black beans (Phaseolus vulgaris L.) on the antioxidant capacity and antiproliferative activity against cancer cell lines of saponins and flavonoids extracted from seed coats, cotyledons and sprouts. Principal component analysis was performed to achieve punctual associations between the black bean saponins and flavonoids concentrations to the antioxidant capacity and the antiproliferative activities. Total phenolic content and antioxidant capacity of extracts were higher when obtained from seed coats, mainly from the 3rd germination day. The extracts obtained from seed coats after 3 and 5 germination days inhibited all cancer cell lines proliferation with no cytotoxicity against control cells. Genistein was related with the activity against mammary cancer cells but flavonols and group B saponins were more related with hepatic and colon cancers. Non-glycosilated flavonols were related with antioxidant capacity.     

Modifying Bitterness in Functional Food Systems

The functional foods sector represents a significant and growing portion of the food industry, yet formulation of these products often involves the use of ingredients that elicit less than desirable oral sensations, including bitterness. Promising new functional ingredients, including polyphenolics, may be more widely and readily employed in the creation of novel functional foods if their aversive bitter taste can be significantly reduced. A number of approaches are used by the industry to improve the taste properties and thus the acceptance of conventional foods that elicit excessive bitterness. This article reviews the most commonly employed techniques, including the use of bitter-modifying additives, which may prove useful for successfully introducing new functional ingredients into this rapidly growing sector.     

硫酸钙晶须表面改性及其性能研究

在不同条件丁使用不同改性剂进行硫酸钙晶须表面改性,探究硫酸钙晶须表面踟陆微观机理,综合实验数据,提出硫酸钙晶须改性较为理想的方案。结果表明：表面活性剂硬脂酸可以作为硫酸钙晶须的改性剂;初始硫酸钙晶须料浆浓度、改性剂掺量、改性时间、改性温度、烘干温度明显影响硬脂酸对硫酸钙晶须表面改性的效果。采用活性指数、接触角、钙离子溶解度和微观照片评定改性效果,建立硬脂酸对硫酸钙晶须表面改性的机理。     

硅烷偶联剂改性对水性UV固化木器涂料性能的影响

利用硅烷偶联剂（KH550）对水性UV固化木器涂料进行改性,并对其力学性能和光学性能进行测试研究,旨在寻找到一种具有较高性能的改性水性UV固化木器涂料。结果表明,当KH550@含量为1．96％-3．23％,干燥时间为40min,紫外灯为3盏时,水性UV固化涂膜的硬度、附着力和抗冲击强度分别达到2H、2级和30kg·cm。KH550的含量对涂膜的光泽度影响不大。     

三种改性方法对青香蕉淀粉物化性质的影响

为了探求一种既尽可能保留青香蕉淀粉的天然特性,又能改善其加工特性的改性方法,对比了复合酶法、乳酸发酵法和挤压膨化法对青香蕉淀粉特性的影响。结果表明：三种改性方法中,复合酶法能够显著提高抗性淀粉的质量分数;通过比较三种改性淀粉的理化特性,复合酶法和乳酸发酵法使结晶度由18.13%分别增加到20.19%和22.06%,而挤压膨化法使结晶度大幅下降至2.16%。复合酶法淀粉的分子解聚程度低,能较好保持原淀粉的颗粒形态,且有助于提高淀粉糊的热稳定性、冷稳定性和凝沉性。而乳酸发酵法和挤压膨化法使热稳定性降低,凝沉性减弱,但能够提高冷稳定性;加工特性研究表明,复合酶法对香蕉原淀粉的色泽影响较小,有助于改善淀粉糊的透明度,提高香蕉淀粉的感官品质。挤压膨化改性淀粉在透明度、溶解度和吸水性方面均有所改善。而乳酸发酵改性对冻融稳定性的影响较小。综上而言,复合酶法是较理想的改性方法。     

纳米SiO2溶胶改性羊毛织物低温染色性能的研究

羊毛表面疏水性类脂层的存在使羊毛纤维表面具有疏水性,染色印花加工过程中阻碍染料的吸附扩散,羊毛织物常规染色需要在高温条件下长时间处理,不仅消耗能源,而且影响其产品质量.文章用纳米SiO2溶胶对羊毛进行改性处理,提高羊毛纤维的表面亲水性.通过实验确定了纳米SiO2溶胶处理条件,包括纳米SiO2浓度、处理温度、时间,对改性处理后羊毛织物的低温染色性能进行测试和分析,并和常规染色效果进行比较.