Study On The Synthesis And Properties Of Polydicyclopentadiene Foam Composites

Polydicyclopentadiene(PDCPD), synthesized by Dicyclopentadiene(DCPD) through a ring-opening metathesis polymerization(ROMP), is one of the novel types of excellent performance engineering plastics, thermosetting. Strong exothermicity of ring-opening metathesis polymerization of dicyclopentadiene, is enough to trigger the foaming, which can be used to design a novel simultaneous foaming polymer composites and the controllable preparing method. During the ROMP, blowing agents are heated to generate bubbles in the matrix, forming porosity or even microcellular structure. The synergetic generation of porosity or microcellular structure will endow the products with some special properties. By selecting kinds of foaming agents, changing synthesis processes, along with a variety of foaming stabilizers, series of composite foams with different structures and properties can be produced, which may bring a further extend on the properties of PDCPD materials.In the ROMP catalyst system, this paper concerned different kinds of inorganic and organic blowing agents, and studied the foaming and polymerization characteristics using frontal polymerization and synchronous polymerization by a chemical blowing method with an appropriate foaming agent. Foaming influences such as catalyst ratioes, blowing agent contents, and the mould temperatures were investigated, as well as the foaming stabilizers, nano calcium carbonate(NPCC) and styrene butadiene rubber(SBR). PDCPD/NPCC/SBR composite foams with different contents of NPCC or/and SBR were prepared, and unfoamed PDCPD samples were also prepared for comparison. Structures and thermal performances of PDCPD compsite foams were analyzed and characterized by SEM, Nano Measurer, DSC and TG et al, so did the mechancial properties be tested by the mechanical testing machine as well.The study found that the heat released in the ROMP process of DCPD could trigger several foaming agents blowing, most of which showed inhibition to the DCPD except for azobisisobutyronitrile(AIBN). In addition, cells in the porosity using AIBN as the blowing agents were smaller and had a narrow distribution. PDCPD Foam samples prepared by synchronous polymerization had smaller and more regular pores and smoother skins. Foams with microcellular structures could be prepared with feasible catalyst ratioes and proper foaming temperatures. Additionally, NPCC as the classic nucleation and reinforcing agent and SBR as the tackifier and toughening agent can make great differences on the composites’ performances, with which the using range of blowing agent was effectively improved, and pores became smaller and more regular, reached the level of microcellular foams as well.Within the mechanical test range, the mechanical properties of PDCPD foam showed a decreasing trend as the blowing agent content increased, and the specific compressive strength got as high as 32.81 MPa/(g?cm-3). In the PDCPD/NPCC/SBR system, with the increase of NPCC or SBR content, the mechanical properties of the composites were firstly increased and then decreased. As the NPCC content got 6.0 wt% and SBR content got 1.5 wt%, the compressive strength, bending strength, tensile strength and impact strength got 18.73 MPa,80.03 MPa,26.76 MPa and 13.79 kJ/m2 respectively, which is the best overall performance. The TG tests showed that the thermal stability of the foam composites improved significantly with the increasing of NPCC content within the measuring range and the decomposition temperature got as high as 460 ℃. Water absorption tests indicated that the PDCPD foams with skin and cell- closed structure have low absorption of water, reaching 0.129 % after more than 96 h’s soaking. Thermal conductivity of the foam sample was tested and the average got as high as 0.042 W/mk, showing an excellent thermal insulation.