Carbon foams prepared from coal tar pitch for building thermal insulation material with low cost

A new approach is provided to resolve the large-scale applications of coal tar pitch. Carbon foams with uniform pore size are prepared at the foaming pressure of normal pressure using coal tar pitch as raw materials. The physical and chemical performance of high softening point pitch(HSPP) can be regulated by vacuumizing owing to the cooperation of vacuumizing and polycondensation. Results indicate that the optimum softening point and weight ratio of quinoline insoluble are about 292℃ and 65.7%, respectively. And the optimum viscosity of HSPP during the foaming process is distributed in the range of 1000-10000 Pa·s. The resultant carbon foam exhibits excellent performance, such as uniform pore structure, high compressive strength(4.7 MPa), low thermal conductivity(0.07 W·m^(-1) ·K^(-1)), specially, it cannot be fired under the high temperature of 1200 ℃.Thus, this kind of carbon foam is a potential candidate for thermal insulation material applied in energy saving building.

The Application of Highly Soluble Amine-terminated Aromatic Polyimides with Pendent Tert-butyl Groups as a Tougher for Epoxy Resin

Polyimides （PIs） with various molecular weights synthesized via the reaction of aromatic diamine monomer containing tert-butyl groups with aromatic dianhydride were highly soluble in common organic solvents and some epoxy resins at room temperature. These PIs can be incorporated in the absence of organic solvent into epoxy resin E51 with the loading below 2 wt% forming EP-PI composites. No phase separation is observed by SEM on cryogenically fractured surfaces of EP-PI composites. The PI can improve mechanical properties, especially impact strength. Adding 2 wt% PI-1.5W, the impact strength reaches to 55 kJ/m^2 with the increase in tensile and flexural strengths by 14% and 3%, respectively. SEM analyses for the fracture surface suggest that PI reduces the crosslink density, improves the plasticity of epoxy resin and changes the mode of fracture from fragile to ductile. Moreover, the glass transition temperature of EP-PI composites was found to increase to a significant extent.

Soluble Polyimide-reinforced TGDDM and DGEBA Epoxy Composites

Polyimide(PI)synthesized from aromatic diamine and dianhydrides via two-step poly-condensation method was highly soluble in TGDDM(MY-720)and DGEBA(E-51)at desirable temperature.TGDDM-PI(M-PI)and DGEBA-PI(E-PI)composites within 0.5%-3%PI loading could be prepared without organic solvent.On the cryogenically fractured surfaces of M-PI and E-PI composites,no obvious heterogeneous phase was observed by SEM.The mechanical properties were promoted significantly by PI,especially for impact strength.Adding 2%PI-2W into MY-720 and E-51 composites,the impact strength increased to 21 and 51 kJ/m2,the tensile strength increased by 62%and 19%,and the flexural strength by 18%and 13%,respectively,with slight increases in tensile modulus.These results were related to the promotion in plasticity of composites and changes in fragile→ductile fracture mode.Moreover,Tg and thermal stability of M-PI and E-PI were increased effectively.