Nucleation Properties Of Foamed Polyolefin Materials

Nucleating agents(NAS)play a very obvious role in the foaming process of polymers and are widely used in the production of ordinary foamed products,but commonly used foaming nucleating agents have limited improvement in foaming efficiency.For this reason,this thesis mainly conducts systematic research work on the theory of cavity nucleation,and the main research conclusions obtained are as follows:1.The analysis of the nucleation mechanism found that the nucleation energy barrier of the cell can be reduced by bringing in natural cavities.Four nucleating agents with typical structures were selected,and it was found that different types of nucleating agents can form different cavity in the PP melt.The cavity formed by β-cyclodextrin(β-CD)and PP melt is the largest,which is suitable for experimental research of cavity nucleation theory.2.Four nucleating agents are added to PP for injection molding and chemical foaming to prepare PP foamed composite materials.β-CD nucleating agent with larger cavity has significantly better foaming quality than other nucleating agents,β-CD The foaming quality of the PP composite foams prepared by the nucleating agent is obviously improved.3.The PP composite foams prepared by four nucleating agents,whether changing the content of the foaming agent or changing the injection temperature,the β-CD nucleating agent with larger cavity,the foaming quality is significantly better than other nucleating agents has a wider foaming temperature window.4.Visually observe the dynamic observation of PP composites foams prepared by four nucleating agents.Through the analysis of cell density and average cell diameter,it is found that β-CD nucleating agent with larger cavity has obvious foaming quality.It is better than other nucleating agents and is consistent with the influence law of the actual injection molding process.5.Synthetic preparation of ZIF-8@MS,needle-like Zn O and spherical Zn O nucleating agents that can bring into the natural pore structure,and add them to PP to prepare foamed PP composites.The cell density of ZIF-8@MS is relatively unchanged.The performance of MS has been significantly improved;the foaming efficiency of acicular Zn O is significantly higher than that of spherical.