【作者】 张凌燕；

【导师】 余永富； 袁继祖；

【作者基本信息】 武汉理工大学 ， 矿物加工工程， 2009， 博士

【摘要】 聚丙烯（PP）作为通用热塑性塑料,力学性能优良,但也存在低温脆性、成型收缩率大、易老化等缺点。聚乙烯（PE）加工性能好,具有一定的刚性和良好的低温冲击性能,是PP改性的良好材料。弹性体乙烯-辛烯聚合物（POE）分子结构中不含有双键,耐候性好,且具有较小的内聚能,较高的剪切敏感性,其表观剪切黏度对温度的依耐性与PP相近,在热稳定性、加工性方面都显示出无可比拟的优势。论文以马来酸酐接枝聚丙烯（PP-g-MAH）作为增容剂,以低密度聚乙烯（LDPE）或POE为增韧剂,以超细矿物微粉为增强剂,采用熔融共混工艺制备了PP/LDPE/白云母共混物和PP/POE/PP-g-MAH/白云母/硅灰石复合材料。对复合材料的拉伸性能、弯曲性能、冲击性能进行了研究,采用扫描电子显微镜（SEM）、差示扫描量热仪（DSC）对复合材料的形态结构和结晶行为进行了研究。主要取得以下结果:（1）通过对硅灰石、白云母的表面改性改善矿物微粉的表面性能,提高与聚丙烯的粘结能力,确定了合适的改性药剂、用量及改性工艺。（2）通过正交试验及单因素试验确定了PP/白云母/LDPE三元复合材料的最佳配方,并对其力学性能、流动性及热学性能进行研究。表明定挠度弯曲强度、缺口冲击强度、洛氏硬度、熔体流动速率和维卡软化温度都有所提高,分别提高了11.1%、13.2%、31.3%、91.89%和0.64%。拉伸强度和定挠度弯曲模量略有下降,拉伸强度从30.72MPa降低到30.54MPa,降低了0.5%。定挠度弯曲模量也降低了1.43%。白云母粒度对复合材料性能的影响表明较适宜的粒度为d₉₀＝16.26μm。共混方式的研究发现,采用直接共混较适宜。采用SEM研究复合材料冲击断面,对微观形貌进行观察,结果表明:改性白云母微粉的粒度宜细,用量宜少有利于分散。随着LDPE用量的增加复合材料的冲击性能提高。TG—DSC研究表明复合材料耐热性均有所提高。（3）通过正交及单因素试验确定了PP/硅灰石/白云母/POE四元复合材料的最佳配方,并对其力学性能、流动性及热学性能进行研究,发现复合材料的拉伸强度达到30.16MPa,较纯PP上升了21.27%,弯曲强度达到31.13MPa,上升了64.97%,弯曲模量为1220.11MPa,较纯PP提高了64.97%,洛氏硬度为18.76,上升了22.61%,维卡软化温度为91.7℃,较纯PP上升了24.93%。复合材料缺口冲击强度基本保持不变,然而复合材料的断裂伸长率大幅下降。采用SEM对复合材料冲击断面微观形貌进行观察,发现白云母、硅灰石的加入使复合材料的冲击断面为韧性断裂,粒度较大的白云母易在PP基体内呈层状分布,长径比优良的硅灰石在断面处的取向整齐,易于提高基体的强度,POE以球状颗粒分布在基体中,与基体黏结良好,有利于提高复合材料的冲击强度,但POE并不能改善硅灰石及云母与PP基体的相容性。通过DSC非等温结晶数据的研究,发现复合材料的结晶度有不同程度的提高,无机矿物粒子在复合材料熔融冷却过程中有明显的结晶诱导作用,为材料性能的提高提供了理论依据。DSC非等温升温曲线研究表明:复合材料的熔融温度有所提高,从而提高了材料的耐热性。（4）初步探讨了复合体系的增韧机理,发现复合材料的强度及韧性的提高并不是云母、硅灰石或者LDPE、POE某一单因素所起的作用,而是体系中三者协同作用的结果。更多还原

【Abstract】 Polypropylene（PP）,as a general-purpose thermoplastics,has a number of excellent mechanical properties,but there are also some other shortcomings,such as low-temperature brittleness,large molding shrinkage and easy to aging.Polyethylene（PE） has a good processing performance,with a certain degree of rigidity and a good impact property at low temperature.So it is a good modifier of PP.There is no double bonds in the molecular structure of the elastomer POE.It has a number of properties,such as good weatherability,smaller cohesive energy, higher sheafing sensitivity and the sheafing viscosity on the temperature witch is close to PP.So it has the unparable advantage of the thermal Stability and the processing.In this paper,PP-g-MAH,LDPE or POE and ultra-fine mineral powder were added as compatibilizer,flexibilizer and reinforcing agent in the PP matrix,respectively.PP/LDPE/muscovite composites and PP/POE / PP-g-MAH/muscovite/wollastonite composites have been prepared by melt blending process.The tensile properties of composite materials,bending properties, impact properties were studied.The Morphology and the Crystallization Behaviorof the composites were investigated by starting electron microscopy （SEM） and differential scanning calorimeter（DSC）,respectively.The study draws the following conclusions:（1） Though modifying the surface of muscovite and wollastonite,the caking capability between mineral particles and PP was improved.The proper modification agent,dosage and modified technology have been decided.（2）The optimum recipe of PP/muscovite/PP-g-MAH/LDPE composite is determined by orthogonal test and single factor experiments.The mechanical properties,fluidity and thermal properties were investigatied.The flexural strength, notched impact strength,Rockwell hardness,melt flow rate and Vicat softening temperature have increased by 11.1%,13.2%,31.3%,91.89%and 0.64% respectively.Tensile strength decrease from 30.72MPa to 30.50MPa slightly and bending modulus decrease by 1.43%.The effect of muscovite particle size on the properties of the composites was studied,and the appropriate size of muscovite is d₉₀＝16.26μm.It is found that the composites should be prepared by directly-blending through the study of the blending-modes.Trough the surly of the surface morphology of the impact fracture by means of SEM,we also find that the small partical size of the modified muscovite and the little dosage can help the powder to disperse.With the increase of the amount of the LDPE,the impact strengh increase.Heat resistance of the composites have been improved through the study of TG-DSC.（3） The optimum processing condition of PP/wollastonite/muscovite/POE is determined by orthogonal test and single factor experiments.Through the researches of the mechanical properties,flowablity and thermal properties,we have found that tensile strength,flexural strength,flexural modulus,Rockwell hardness and vicat sorting point are increased to 30.16MPa,31.13MPa, 1220.11MPa,18.76.,91.7℃,increaced by 21.27%,64.97%,64.97%,22.61%,24.93%. However,the Charpy notched impact strength keeps steady and the fracture elongation decreases dramatically.The interface between the fillers and the matrix and the cause,which improves their performance,are explained through analyzing the surface morphology of the impact fracture by means of SEM.The analysis of the specimen fracture also indicates that the interface between the muscovite and wollastonite and the matrix is strong enough to transmit loads to the mineral particles,so as to play the reinforcing role of the mineral particles.The layered distribution of muscovite,which has large particle-size and the orientation of the wollastonite which has lager LD ratio,are apt to improve the strength of the composite.POE is distributed in the matrix in the form of spherical particle and boned well with the matrix,so as to improve the impact strength.But POE could’t improve the caking capability of the mineral particles and PP.DSC is used to characterize the melting and crystallization behavior of the composites.The results of non-thermal crystallization data show that the composites have a higher erystallinity.And the inorganic particles have an obvious induced crystallization of PP during cooling,so it is theoretically explained the cause of improved properties. Through the non isotheirmal heating curves,we can see that the melting temperature and heat resistance are enhanced.Toughening mechanism of the composite was preliminary investigated, founding that the improved strength and toughness was not the result of wollastonite,mica or POE,but the outcome of synergisms of the three in the matix.更多还原