Low‐volatility acetals to upgrade the performance of melamine–urea–formaldehyde wood adhesive resins

1,1,2,2‐Tetramethoxyethane (TME), a high boiling point acetal derived from glyoxol, lhas been shown to upgrade the performance of melamine‐urea‐formaldehyde (MUF) and some UF resins used for wood adhesives. This affords the possibility of decreasing the percentage of resin used in the preparation of wood panels without volatilizing the TME acetal used.     

红外辐射涂料制备技术与方法的研究

根据红外辐射涂料1－5μm的辐射机制,针对实际应用中出现的各种问题,从红外辐射涂料粉体基料的原材料选择与合成,载体粘结剂原材料的选择与制备等方面出发,探讨了红外辐射涂料的制备技术与方法。     

广东省木材胶粘剂的现状及发展对策

本文阐述了国内外木材胶粘剂的进展,广东省木材胶粘剂的生产,应用状况和存在问题,提出了广东省木材胶粘剂的发展对策。     

Predicting the service-life of adhesively-bonded joints

A fracture-mechanics approach has been used to predict the cyclic-fatigue performance of the adhesively-bonded single-lap joint and a typical bonded component, represented by an adhesively-bonded `top-hat' box-beam joint. The joints were tested under cyclic-fatigue loading in either a `wet' or `dry' environment, respectively. Several steps were needed to predict the cyclic-fatigue lifetime of these joints. Firstly, fracture-mechanics tests were used to obtain the relationship between the rate of fatigue crack growth per cycle, da/dN, and the maximum strain-energy release-rate, G <sub>max</sub>, applied during the fatigue cycle for the adhesive/substrate system under investigation, in both a `dry' and a `wet' test environment. Secondly, analytical and finite-element theoretical models were developed to describe the variation of the strain-energy release-rate with crack length, as a function of the applied fatigue loads, for the single-lap joint and the `top-hat' box-beam joint. Thirdly, the experimental results from the short-term fracture-mechanics tests, obtained under similar test conditions and in the same environment as were used for the single-lap or bonded box-beam joints, were combined with the modelling results from the theoretical studies. This enabled the cyclic-fatigue performance of the single-lap or bonded box-beam joints to be predicted over relatively long time-periods. Finally, the agreement between the theoretical predictions and the experimentally-measured cyclic-fatigue behaviour for the joints was found to be very good.     

GAP推进剂粘合剂固化体系力学性能的研究

在保证推进剂加工工艺性能和能量性能的前提下,通过化学共聚的方法,选用主链柔顺性较好、且在推进剂中可单独用作含能粘合剂的3,3-双(叠氮甲基)氧丁环/四氢呋喃的共聚物(BAMO/THF)来改善聚叠氮缩水甘油醚(GAP)交联网络结构,在此基础上再加入合适的扩链剂和交联剂,所得弹性体的力学性能有大幅度的提高。当固化参数R=1.3,m(GAP)∶m(BAMO/THF)=75∶25,以1,4-丁二醇(BDO)为扩链剂,异佛尔酮二异氰酸酯(IPDI)/多异氰酸酯(N100)为固化剂,胶片的拉伸强度可达到1.03MPa,断裂伸长率达到505.3%。     

A Novel Bioinspired Switchable Adhesive with Three Distinct Adhesive States

A novel switchable adhesive, inspired by the gecko's fibrillar dry attachment system, is introduced. It consists of a patterned surface with an array of mushroom‐shaped pillars having two distinct heights. The different pillar heights allow control of the pull‐off force in two steps by application of a low and a high preload. For low preload, only the long pillars form contact, resulting in a low pull‐off force. At higher preload, all pillars form contact, resulting in high pull‐off force. Even further loading leads to buckling induced detachment of the pillars which corresponds to extremely low pull‐off force. To achieve the respective samples a new fabrication method called double inking is developed, to achieve multiple‐height pillar structures. The adhesion performance of the two‐step switchable adhesive is analysed at varying preload and for different pillar aspect ratios and height relations. Finally, the deformation behavior of the samples is investigated by in situ monitoring.     

可控环境下的结构胶粘剂拉伸测试系统

根据结构胶粘剂力学性能测试的特点,提出了一种在可控环境条件下对结构胶粘剂进行拉伸性能测试的自动化测试系统,并详细介绍了该测试系统的设计原理、硬件组成和软件实现,以及环境温度和湿度等的控制方法。最后采用该系统对金属铜丝和一种结构胶粘剂薄膜进行了拉伸测试。测试结果表明,该系统自动化程度高,测试结果准确,具有较高的实际应用价值。     

雷达隐身技术的研究现状及其展望

叙述了雷达隐身技术的工作原理、类型及研究现状,综述了雷达吸波涂层中使用的吸收剂、胶粘剂和助剂,并介绍了以聚氨酯为胶粘剂的涂层基体,对聚氨酯复合材料进行了展望.回顾了雷达吸波材料的研究和发展,介绍了雷达吸波材料若干新的发现、性能及应用,同时展望了雷达吸波材料的发展趋势和研究发展的重点.     

乳液型聚丙烯酸酯医用压敏胶的改性研究

分别采用多步乳液聚合法和乳液共混法改性制备粘接性能较好的乳液型聚丙烯酸酯医用压敏胶。分析讨论了种子乳液的组成、预溶胀时间和预溶胀次数、引发剂种类、原位聚合温度等因素对压敏胶粘接性能的影响。结果表明,多步乳液聚合法是全面提高粘接性能的有效方法;而基于预乳化半连续聚合工艺的乳液共混法,仅在一定范围内有改性效果。     

顶空进样气相色谱法分析溶剂型木器涂料中的苯系物

采用顶空进样气相也谱法对溶剂型木器涂料中的苯系物进行分析,所使用的方法能较好地避免基质的干扰。在给定的浓度范围内,各目标组分呈现良好的线性相关,检测限与定量限也都在国家规定的最大限量之下,回收率在85．6％-105％之间,日内精密度〈7．2％,日间精密度〈9．6％。