Study On A Novel Route To Toughneing And Strengthening And Modified Mechanism Of PA66

The toughness of PA6,PA66 will be improved by adding polyolefin, highperformance engineering plastics, inorganic non-elastomer and other PA.Nowadays, it has been the main research hot point to exploit and research of ultratoughness and high-powered PA6,PA66 blends by adding polyolefin elastomer orusing nano-technology. Though the toughness of PA can be improved by adding traditional rubber andthermoplastic elastomer, the application of the material has been influencedbecause of the loss of the strength, rigidity, and temperature of thermaldeformation.The loss of rigidity and temperature of thermal deformation may beavoided by using inorganic particle, but the compatibility between the particle andmatrix still will be a problem. If the compatibility is poor, it will produce defect,then the defect will bring on stress concentration, and the performance of PA willbe reduced. The nano-composites can obviously improve the bending elasticmodulus and have the properties of inflaming retarding, heat resisting, but theymay be poorer in toughening than using elastomer. In this paper, we still use elastomer to toughen PA6,PA66, then the toughnessmay be improved enormously. The reason to reduce the toughness using traditionalrubber to toughen PA is that the rubber particle among PA6,PA66 matrix is bigger,it will need to add more rubber in order to realize brittle-ductile transition, then itwill cause the loss of modulus (because the modulus of rubber is lower). A new kind of material, Ultra-fine Full-Vulcanized Acrylate PowderedRubber (to be called UFAPR for short in the following article ), Ultra-fineFull-Vulcanized Butadiene-acrylonitrile Powdered Rubber (to be called UFNPRfor short), Ultra-fine Full-Vulcanized Carboxylated NBR Powdered Rubber (to becalled UFXPR for short) has been used to toughen PA6,PA66 through melting 4北 京 化 工 大 学 博 士 学 位 论 文blending in this paper. The crystal properties, mechanical properties, rheologicalproperties of PA6,PA66 and its alloy has been investigated. The major works of this study are summarized as following: 1. The related literatures on toughening of PA6,PA66 resins have beenreviewed systematically and the outline of this dissertation has been summarized indetail. 2. In this paper, first of all, systematic study has carried out on the crystalproperties and crystal dynamic of PA6,PA66 and its blends. The results show thatthe growing crystal way of PA6,PA66 and its blends is same. On the samecrystallization temperature, the degree of rubber powdered to affect Avramigrowing coefficient k of blends is UFAPR>UFXPR>UFNPR. By adding a littlerubber powdered, the crystallization rate can be increased obviously, the surfacefree energies of the developing crystals is reduced. All these show that rubberpowdered is a nucleation agent of PA6,PA66. The degree of rubber powdered toaffect crystallization rate and nucleation rate is UFAPR>UFXPR>UFXPR. Thedisperse uniformity degree of rubber in PA6,PA66 is UFAPR>UFXPR>UFXPR. Italso can be seen from the study on the cooling crystallization behavior of PA6,PA66 and its blends that the blends'w1/2 reduce and Xc rise comparing with PA6,PA66, which means the distribution of crystal grain narrowed and crystallizationdegree increased and it indicates rubber powdered acts as the function ofheterogeneous nucleation. The results on crystallization behavior of PA6,PA66 and its blends usingPLM show that the radium of crystallite reduces and the number increase byadding rubber powdered, which indicate that rubber powdered acts as the nuclearformulation and it makes the size of crystallite little and the crystallization rateincrease. 3. Studies have been made on mechanical properties and crystalline structureas well as crystallization kinetics of the PA6,PA66 composites. The results showthat UFAPR, UFNPR and UFXPR not only a good toughening agent but also anucleation agent for...