阻燃聚甲醛复合材料的制备及其性能研究

发布时间：2018-02-16 06:55

本文关键词： 聚甲醛包覆改性聚磷酸铵阻燃　出处：《安徽大学》2017年硕士论文　论文类型：学位论文

【摘要】：聚甲醛(POM,又名"夺钢"、"赛钢"),是五大工程塑料之一。因其高强度、高模量的性能特点,经常被用来替代铜、铁、铝等金属材料。此外聚甲醛还具有很好的耐疲劳性、自润滑性和尺寸稳定性,这使得聚甲醛被广泛应用于工业机械、汽车、电子电气、运动器械等行业。聚甲醛树脂结晶度高,缺口极为敏感缺口冲击强度低,且聚甲醛热稳定性差,极限氧指数仅为15%,易燃烧,燃烧释放大量有毒甲醛气体。因其以上两个特点(脆性大和易燃烧)极大的限制了聚甲醛在生产中的发展,特别是近年来我们化工厂火灾不断,对阻燃性能的要求也是越来越高。迄今为止国内外的研究工作者们从未停止对聚甲醛的阻燃的探索,但聚甲醛阻燃的问题却一直未能得到很好的解决。本文主要研究聚磷酸铵阻燃的改性及其改性阻燃剂阻燃聚甲醛,研究APP粒子的包覆改性过程以及改性粒子的阻燃效果。本课题主要研究内容包括以下几个方面:首先,研究了阻燃剂聚磷酸铵(APP)包覆改性的合成过程,分别制备以热塑性聚氨酯和热固性聚氨酯为囊材的PUAPP粒子。对PUAPP粒子采用红外吸收分析、透射电子显微镜电镜(TEM)等表征方法研究其结构特点,PUAPP的红外吸收峰有明显的羰基吸收峰,说明PUAPP中具有聚氨酯成分。此外通过透射电镜观察PUAPP粒子形貌,可以观察到PUAPP粒子具有明显的核壳结构。研究了 PUAPP粒子的水溶性和疏水性,表明PUAPP粒子较APP粒子具有更低的水溶性和较强的疏水性。较强的疏水性表明PUAPP阻燃粒子与聚甲醛基体有更好的相容性。此外还对比了 PUAPP粒子的热稳定性能,通过热稳定分析,可知PUAPP的热稳定性更好。在两种不同的聚氨酯包覆改性聚磷酸铵粒子有着不同的效果,其中以热固性聚氨酯树脂改性聚磷酸铵粒子具有更好的疏水性、热稳定性。APP粒子的表面改性使得APP粒子和聚合物之间有更好的相容性,使得APP阻燃粒子的应用范围更加的广泛,在这拓展APP阻燃剂应用方面具有一定的现实意义。其次,研究了不同改性聚磷酸铵粒子阻燃POM的阻燃效果。结果表明:包覆改性的聚磷酸铵粒子阻燃性能明显优于未改性聚磷酸铵粒子,在使用相同配比情况下,使用PUAPP粒子阻燃的POM复合材料的UL-94可以达到V-0级别(APP阻燃复合材料为V-1),极限氧指数(LOI)可达到66.5%。在相同阻燃剂比例的提前下,PUAPP粒子的阻燃效果明显优于APP的阻燃效果。PUAPP粒子表面的PU层可以充当成炭剂,增强复合材料的成炭能力。此外所形成炭层还可以有效隔离酸性物质和聚甲醛基体的接触,减缓酸性物质对POM基体分解的催化作用;包覆改性聚磷酸铵粒子在阻燃POM复合材料的燃烧过程中具有更低热释放速率(HRR)、总热释放量(THR)以及更高的成炭率。两种改性的PUAPP在阻燃方面均表现优于APP;热固型PUAPP在阻燃方面比热塑性PUAPP表现更佳;对比未改性APP时,在使用包覆改性APP阻燃聚甲醛复合材料在力学性能方面表现更加的优异。其中在拉伸强度方面表现突出,可以达到37.0 MPa,缺口冲击强度为4.1 kJ/m2力学性能基本保留优于未改性APP阻燃复合材料。PUAPP是以PU为囊材料的微胶囊粒子,其表面的PU与POM的结合力明显优于无机粒子和POM之间的结合力,而在宏观表现出较好的物理力学性能。对比两组不同囊材料的PUAPP在复合材料中的效果,以热固性PUAPP表现更加突出。聚甲醛(P O M)因为其特点的结构特点,使其成为为难阻燃的复合材料之一。研究阻燃聚甲醛复合材料时,在加工过程少量的酸、碱即会引发聚甲醛基体的大量分解,此外聚甲醛基体也对温度非常敏感,加工温度区间约20℃左右。聚磷酸虽然具有较好的阻燃效果,但聚磷酸铵在燃烧过程中分解产生出的酸性物质会催化聚甲醛基体的分解,加速聚甲醛的燃烧。这就使得APP在阻燃POM时有两方面表现,一方面可以对POM进行脱水成炭,有效降低热释放速率提高阻燃性能;另一方面,在燃烧过程中APP粒子产生的酸性物质加速POM分解,不利于阻燃性能的提高。
[Abstract]:Polyoxymethylene (POM, also known as "seize steel", "steel"), is one of the five major engineering plastics. Because of its high strength, high modulus characteristics, are often used to replace copper, iron, aluminum and other metal materials. In addition, POM has good fatigue resistance, self lubrication and size the stability, which makes the POM is widely used in industrial machinery, automobile, electronic and electrical, sports equipment and other industries. The poly formaldehyde resin with high crystallinity, the gap is extremely sensitive to the low impact strength, and thermal stability of polyoxymethylene, limit oxygen index is only 15%, easy combustion, combustion release toxic formaldehyde gas. Because of the above two characteristics (brittleness and easy combustion) greatly limits the development of POM in production, especially in recent years, our chemical plant fire, the flame retardancy of the requirements is also more and more high. So far the domestic and foreign research workers never stop to POM resistance Gas exploration, but the flame retardant polyoxymethylene problem has not been solved well. This paper mainly studies the polyphosphate flame modification and modification of flame retardant POM, APP particle coating process and flame retardant effect of modified particles. The main contents of this paper include the following: first of all, the flame retardant ammonium polyphosphate (APP) synthesis process modification, were prepared with thermoplastic polyurethane and thermosetting polyurethane as capsule material. PUAPP particles of PUAPP particles by infrared absorption analysis, transmission electron microscope electron microscope (TEM) to study the structural characteristics of the infrared characterization method, PUAPP the absorption peak has obvious carbonyl absorption peak, indicating the polyurethane components of PUAPP. In addition to observe PUAPP particle morphology can be observed by transmission electron microscope, PUAPP particle has obvious core-shell structure of PUAPP particles. The water solubility and hydrophobicity, showed that the PUAPP particles with APP particles with lower water solubility and strong hydrophobicity. Strong hydrophobic shows have better compatibility with the POM matrix PUAPP flame retardant particles. In addition, compared to the thermal stability of PUAPP particles, the thermal stability analysis, the better thermal stability PUAPP. In two different polyurethane coating modified ammonium polyphosphate particles have different effects, the modified hydrophobic poly ammonium phosphate particles has better thermosetting polyurethane resin, the thermal stability of.APP particle surface modification which have better compatibility between APP particle and polymer, making the application of flame retardant APP the particle becomes more widespread, has a certain practical significance in the development of APP flame retardant application. Secondly, study the different modified ammonium polyphosphate particles of flame retardant POM flame retardant effect. The results show that the coating The flame retardant ammonium polyphosphate particles has better performance than the unmodified poly ammonium phosphate particle, with the same proportion of cases, the use of PUAPP flame retardant POM composite particles of UL-94 can reach V-0 level (APP Flame Retardant Composites of V-1), the limiting oxygen index (LOI) can reach 66.5%. In the same proportion of flame retardant in advance under the PU layer of flame retardant effect of.PUAPP particle surface of PUAPP particles in flame retardant effect is obviously better than that of APP can act as a charring agent, reinforced carbon composites. In addition to the ability of the formation of carbon layer can effectively isolate the acidic substances and the POM matrix contact, slow acid catalytic effect on the decomposition of the POM matrix; coating modified poly ammonium phosphate particle in the combustion process of flame retardant POM composite has more low heat release rate (HRR), total heat release (THR) and char yield higher. Two kinds of modified PUAPP were excellent in flame retardant. APP; PUAPP in flame retardant thermosetting plastic PUAPP on heat performance better; compared with unmodified APP, the use of modified APP flame retardant POM composite performance in mechanics performance more excellent. The outstanding performance in terms of tensile strength, can reach 37 MPa, the notched impact strength is 4.1 kJ/m2 mechanical properties the basic reserve is better than that of the unmodified APP composite flame retardant.PUAPP is microencapsulation with PU as capsule material, combined with the surface of the PU and POM of the binding force between the force is obviously better than that of inorganic particles and POM, and better physical mechanical properties in macro performance. Compared the effects of the two groups of different materials in PUAPP capsule in the composite, thermosetting PUAPP performance more prominent. Polyoxymethylene (P O M) because of its structure characteristics, make it become one of difficult flame retardant composites. Study on flame retardant POM Composites, processed in A small amount of acid alkali process, which will lead to a large number of decomposition of the POM matrix, in addition the POM matrix is very sensitive to temperature, processing temperature of about 20 DEG C. Poly phosphoric acid has good flame retardant effect, but ammonium polyphosphate in the combustion process of acid decomposition will produce catalytic decomposition of POM matrix and accelerate POM combustion. This makes the APP has two aspects in flame retardant POM, on the one hand, POM can be dehydrated into carbon, reduce the heat release rate and improve the flame retardant performance; on the other hand, acidic substances of APP particles in the combustion process to accelerate the decomposition of POM, is not conducive to flame retardant performance.

【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ326.51;TB332

【参考文献】