Study On Relationship Between Rheological Characterization And Mechanical Properties Of Long Carbon Chain Nylon/Functional Polypropylene Blends

Nylon is a kind of thermoplastic engineering plastic,which is now widely used both at home and abroad.It has so good mechanical and thermal properties that it has been widely used in various industries.However,its low impact strength has limitied it using in some special fields.Therefore,it is necessary to modify it to improve its toughness.Nylon can be blended with functional elastomers,functional polyolefins or inorganic fillers to produce super-toughness materials.But in order to get the super-toughness formula,it is relatively complicated to carry out a large number of experiments based on orthogonal design method.Polypropylene grafted maleic anhydride(PP-g-MAH)was used as the second phase to toughen nylon in this study.Through investigating the effects of blend compositions and the types of long chain nylon on the mechanical properties and rheological behavirors of nylon/PP-g-MAH reactive blends,we tried to find the corresponding correlations between the key mechanical parameters and the characteristic viscoelastic parameters and built the relationships between rheological behaviors and mechanical properties of these reactive blends.Taking advantage of the features of dynamic rheology tests to determined quickly the optimum compositions of nylon/PP-g-MAH reactive blends.The main results are as follows:(1)The addition of PP-g-MAH increase significantly the impact strength of nylon 1212 and nylon 12 and also improve the tensile strength of nylon 12.The maximum impact strength of nylon 1212/PP-g-MAH blends is 19.59 kJ/m2,which is about 3 times as high as that of pure nylon 1212.The maximum impact strength of nylon 12/PP-g-MAH blends is 59.3 kJ/m2,which is about 5.5 times as high as that of pure nylon 12,and its maximum tensile strength is 66.5 MPa,about 1.5 times as high as that pure nylon 12.(2)With increasing of PP-g-MAH,the rheological behaviors of nylon 1212/ PP-g-MAH and nylon 12/PP-g-MAH blends exhibit "liquid-solid" transition and stress yield phenomena,and the storage modulus curves of the blends show obvious "the second plateau in the low frequency regions.(3)With the addition of PP-g-MAH,the melting points of nylon 1212 and nylon 12 change slightly,the melting peaks are close to each other indicating that the compatibility the blends are improved,the melting and crystallization enthalpy of the nylon phase in the blends decrease.(4)Both nylon 1212/PP-g-MAH blends and nylon 12/PP-g-MAH blends show a gel point in the test ranges.The impact strength of nylon 1212/PP-g-MAH blends at the gel point is the maximum,while the impact strength and tensile strength of nylon 12/PP-g-MAH blends corresponding to the gel point are higher than those of the near points.The morphologies of the blends at the gel points showed a special "network" structure,indicating that the rheological properties of the blends are related to their mechanical properties.