三聚氰胺泡沫的增强改性及其夹芯复合材料的力学性能研究

发布时间：2018-07-27 20:13

【摘要】：三聚氰胺泡沫是一种本征阻燃的新型开孔泡沫,具有阻燃性高、吸音性能好、隔热性能佳、原材料成本低廉等多种优势,在隔音、保温、建筑、农业、交通运输、航空航天等领域具有良好的市场前景和潜在的应用价值。三聚氰胺大分子中存在刚性较大的三嗪基团,因而在力学性能上存在脆性大、强度低、易粉化等缺陷,这大大限制了三聚氰胺泡沫尤其是硬质三聚氰胺泡沫材料在工业上的应用。因此进一步提高三聚氰胺泡沫的力学性能对拓展和提升三聚氰胺泡沫产品的应用范围具有重要意义,成为近年来的研究热点之一。为了分析研究三聚氰胺泡沫的增强方法,以及三聚氰胺泡沫在高性能夹芯复合材料中的应用,本课题提出以三聚氰胺树脂为原料制备硬质泡沫材料,通过优化工艺、化学改性等方法研究影响三聚氰胺泡沫性能的因素及规律,并在此基础上研究以三维中空织物做骨架,三聚氰胺泡沫做填充芯材的新型夹芯复合材料的制备方法及其性能特征。在三聚氰胺泡沫的制备工艺优化方面,采用正交实验设计的方法,以压缩力学性能作为评价指标,对发泡工艺参数进行了三因素四水平的优化设计。结果表明在所选参数范围内最优发泡工艺条件为添加发泡剂3%,固化剂12%,乳化剂5%,发泡温度时间先保持120℃2小时,后保持70℃2小时。通过SEM照片发现发泡工艺参数会影响泡孔的结构。泡孔小,骨架粗的泡沫压缩力学性能最好。通过DSC测试发现加入固化剂会促使树脂固化放热过程更为均匀,并且能在较低的温度下放热固化,而加入发泡剂后树脂固化需要更高的温度。通过流变测试发现树脂在不加入固化剂或较低发泡温度下粘度变化较为缓慢,与发泡过程难以匹配,造成发泡失败。DSC及流变测试从侧面反应了发泡工艺条件最优值的形成原因。在三聚氰胺树脂的改性方面,分别使用1,4-丁二醇、三羟乙基异氰尿酸酯、PEG-400和PVA-1788四种试剂对其进行化学改性,在最优发泡条件下进行烘箱发泡,并通过对泡沫成品进行压缩性能、FT-IR、TG、LOI、粉化率、游离醛等多项测试,综合表征硬质三聚氰胺泡沫的性能指标,对改性剂种类及添加比例进行优化筛选。压缩测试结果表明小分子改性剂的增强效果优于长链段改性剂,在添加三聚氰胺质量20%的三羟乙基异氰尿酸酯时,泡沫的压缩性能最好,此时改性三聚氰胺泡沫的压缩强度比泡沫原样提高了1倍。在加入改性剂后,泡沫粉化率均有所下降,使得其在受到外力时更难发生脆断,降低了粉化程度,从而提高了力学性能。通过SEM照片可以看出在表观密度为0.3g/cm3时,泡沫已产生部分泡壁结构,并且在泡壁上有通孔贯穿。当泡孔直径越小,泡沫力学性能越好。TG和LOI测试表明在添加改性剂后泡沫的热稳定性降低,阻燃性能有所下降,但在添加改性剂比例范围内LOI仍能达到30以上,仍具有较好的阻燃性；由于未添加甲醛消除剂,所有三聚氰胺泡沫游离醛含量较高,均在1mg/g左右。在三聚氰胺泡沫夹芯复合材料的制备方面,将20%三羟乙基异氰尿酸酯改性的硬质三聚氰胺泡沫分别与10mm、30mm、37mm高度的三维网格中空织物结合起来,制备出三聚氰胺泡沫夹芯复合材料。对夹芯材料的压缩特性和弯曲特性进行分析,结果表明中空网格织物对硬质三聚氰胺泡沫的压缩性能提升有限,但对其弯曲性能有着较大的提高作用。由于中空织物经纬异性,夹芯复合材料经纬向的弯曲性能也有所不同,其纬向弯曲性能好于经向弯曲性能。
[Abstract]:Melamine foam is a new type of flame-retardant open hole foam. It has many advantages, such as high flame retardancy, good sound absorption, good heat insulation, low cost and so on. It has good market prospect and potential application value in the fields of sound insulation, insulation, construction, agriculture, transportation, aerospace and other fields. The larger three azine group has the defects of brittleness, low strength and easy to powder in mechanical properties, which greatly restricts the application of melamine foam, especially the hard melamine foam, in industry. Therefore, further improvement of the mechanical properties of melamine foam is used to expand and enhance the application of melamine foam products. In order to analyze and study the enhancement method of melamine foam and the application of melamine foam in high performance sandwich composites, this topic proposed the preparation of hard foam material by using melamine resin as raw material, and Study on the method of optimization, chemical modification and other methods. On the basis of the factors and laws of the performance of melamine foam, the preparation method and performance characteristics of a new type of sandwich composite with three dimensional hollow fabric as skeleton and melamine foam as filling core are studied. The method of orthogonal experiment design is used to compress the mechanical properties of the melamine foam preparation process. As an evaluation index, the optimum design of three factors and four levels of foaming process parameters is carried out. The results show that the optimum foaming process conditions are adding foaming agent 3%, curing agent 12%, emulsifier 5%, foaming temperature for 2 hours at 120 C for 2 hours and then 70 C for 2 hours. The foaming process parameters will be found to be influenced by SEM photos. The structure of the bubble hole is small and the skeleton thick foam compresses the best mechanical properties. Through the DSC test, it is found that adding the curing agent will make the resin curing and exothermic process more uniform, and can heat and solidify at a lower temperature, and the resin curing requires a higher temperature after adding the foaming agent. The resin is not added to the solid through the rheological test. The change of the viscosity of the chemical agent or at the lower foaming temperature is relatively slow, which is difficult to match with the foaming process, resulting in the failure of the foaming.DSC and the rheological test on the side of the foaming process. In the modification of melamine resin, 1,4- butanediol, three hydroxyethyl isocyanurate, PEG-400 and PVA-1788 were used respectively. The agent was chemically modified, and the oven was foamed under the optimal foaming condition. The performance index of the hard melamine foam was characterized by a number of tests on the compression performance of the finished product, FT-IR, TG, LOI, the powder rate and free aldehyde, and the variety and proportion of the modifier were optimized. The compression test results showed that the small molecule was small. The reinforcing effect of the modifier is better than the long chain modifier. When the three hydroxyethyl isocyanurate with 20% melamine mass is added, the compression performance of the foam is the best. At this time, the compressive strength of the modified melamine foam is 1 times higher than that of the original foam. After adding the modifier, the foam powder rate decreases somewhat, making it more effective when it is subjected to external force. It is difficult to make brittle fracture and reduce the degree of pulverization, thus improving the mechanical properties. Through the SEM photo, it can be seen that when the apparent density is 0.3g/cm3, the foam has produced part of the bubble wall structure and has through holes through the bubble wall. When the diameter of the bubble is smaller, the better the mechanical properties of foam.TG and LOI show that the heat stability of the foam after the addition of modifier. The flame retardancy decreased, but the LOI still reached more than 30 in the proportion of the modifier, and still had better flame retardancy. The free aldehyde content of all melamine foam was higher than 1mg/g without formaldehyde elimination agent. In the preparation of melamine foam core composites, 20% three hydroxyethyl isocyanate was used. The hard melamine foam modified by urate was combined with the three-dimensional mesh of 10mm, 30mm and 37mm, and the melamine foam sandwich composites were prepared. The compression properties and bending properties of the sandwich materials were analyzed. The results showed that the compression performance of the hollow mesh fabric for the hard melamine foam was limited. However, the flexural properties of the sandwich composites are different because of the longitude and latitude of the hollow fabric. The warp bending performance of the sandwich composites is better than that of the warp bending.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33;TQ328

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