PMMA基体组成调控对其增韧的影响

发布时间：2018-12-19 20:39

【摘要】：聚甲基丙烯酸甲酯(PMMA)是刚性无定形聚合物,具有优异的耐紫外线性能与光学性能使PMMA被广泛的应用于日常生活中多个领域。PMMA的主要缺点是脆性以及对缺口的敏感性,因此对PMMA的增韧改性研究一直很受研究人员的关注。本论文利用乳液聚合方法合成了以聚丁二烯橡胶(PB)为核,以聚甲基丙烯酸甲酯(PMMA)为壳的PB-g-MMA核壳粒子增韧剂,核壳比控制为80/20,将其用于PMMA树脂的增韧。由于PMMA基体树脂缠结密度低,增韧PMMA断裂过程中产生银纹,因此很难达到较高的冲击强度。因此,本文将与PMMA具有良好相容性的聚碳酸酯(PC)、聚偏氟乙烯(PVDF)分别引入到PMMA基体中,调控基体的链缠结密度,从而获得更好的冲击强度。研究结果表明,在PMMA/PB-g-MMA共混体系中,当PB-g-MMA含量为20wt%,PC含量为0%时,PMMA的冲击强度从9J/m提高到29J/m,增加了近2倍。基体中随着PC含量的增加,材料的冲击韧性不断提高,当PC含量为40wt%时,共混物的冲击强度达到51J/m,PMMA的冲击性能提高了4倍。另一方面,在体系中加入Mg O促进PC与PMMA的酯交换反应,结果共混物表现出更高的冲击韧性。断裂机理表明,PB-g-MMA增韧PMMA共混物主要以银纹方式发生断裂,PC的引入能够使共混物发生剪切屈服断裂,提高了材料的韧性。在PMMA/PVDF体系中,当PB-g-MMA含量为20wt%,基体为PMMA树脂时,共混物的冲击强度为30J/m。基体中随着PVDF含量的增加,材料的冲击韧性不断提高,当PVDF含量为40wt%时,共混物的冲击强度高达300J/m。断裂机理表明,PVDF的引入可以使PMMA共混物发生剪切屈服断裂,吸收大量的冲击能,提高了材料的韧性。此外,固定PVDF含量为30wt%,改变共混物中PB-g-MMA核壳粒子的含量。研究发现随着核壳粒子含量的增加,共混物的冲击强度逐渐提高。当PB-g-MMA含量为30wt%时,材料冲击强度接近350J/m。增韧机理表明,橡胶粒子的空洞化和基体的剪切屈服是导致材料发生韧性断裂的根本原因。因此,通过在PMMA基体中引入PC、PVDF显著提高了PB-g-MMA对PMMA的增韧效率,获得了冲击韧性优异的PMMA共混材料。
[Abstract]:Poly (methyl methacrylate) (PMMA) is a rigid amorphous polymer with excellent UV resistance and optical properties. PMMA is widely used in many fields of daily life. The main disadvantage of PMMA is its brittleness and its sensitivity to notches. Therefore, the study of toughening and modification of PMMA has been paid much attention by researchers. In this paper, PB-g-MMA core-shell toughening agent with polybutadiene rubber (PB) as core and polymethyl methacrylate (PMMA) as shell was synthesized by emulsion polymerization. The core-shell ratio was controlled to 80 / 20, which was used to toughen PMMA resin. Because of the low tangle density of PMMA matrix resin and the formation of crazing during the fracture of toughened PMMA, it is difficult to achieve high impact strength. Therefore, the polycarbonate (PC),) polyvinylidene fluoride (PVDF), which has good compatibility with PMMA, is introduced into the PMMA matrix respectively to regulate the chain entanglement density of the PMMA matrix and obtain better impact strength. The results show that when the content of PB-g-MMA is 20 wtand the content of PC is 0, the impact strength of PMMA increases from 9J/m to 29J / m, which is nearly twice as high as that of PMMA. With the increase of PC content in the matrix, the impact toughness of the blends increases continuously. When the content of PC is 40 wt%, the impact strength of the blends reaches 51J / mMMA, and the impact strength of the blends increases by 4 times. On the other hand, the addition of Mg O in the system can promote the transesterification between PC and PMMA, resulting in higher impact toughness of the blends. The fracture mechanism shows that the fracture of PB-g-MMA toughened PMMA blends is mainly in the form of silver stripes, and the introduction of PC can make the blends shear yield fracture and improve the toughness of the blends. In PMMA/PVDF system, when the content of PB-g-MMA is 20 wtand the matrix is PMMA resin, the impact strength of the blend is 30 J / m. With the increase of PVDF content in the matrix, the impact toughness of the blends increases. When the content of PVDF is 40 wt%, the impact strength of the blends reaches 300J / m. The fracture mechanism shows that the introduction of PVDF can make the PMMA blends shear yield fracture, absorb a large amount of impact energy, and improve the toughness of the materials. In addition, the content of PB-g-MMA core-shell particles in the blend was changed by fixing the content of PVDF for 30 wt. It is found that the impact strength of the blends increases with the increase of the content of core-shell particles. When the PB-g-MMA content is 30 wt%, the impact strength of the material is close to 350 J / m. The toughening mechanism shows that the cavitation of rubber particles and the shear yield of the matrix are the fundamental causes of ductile fracture. Therefore, by introducing PC,PVDF into the PMMA matrix, the toughening efficiency of PB-g-MMA to PMMA was improved significantly, and the PMMA blend with excellent impact toughness was obtained.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O632.52

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