Preparation and properties of an interpenetrating network polymer based on polydicyclopentadiene and phenolic resin

In this paper, phenolic resin (PF) and dicyclopentadiene (DCPD) monomers were mixed in different proportions. Under the action of a new generation of ruthenium carbene catalysts, DCPD was polymerised in situ. Polydicyclopentadiene (PDCPD)/PF interpenetrating polymer networks (IPNs) were prepared using the casting curing moulding process. The structure and properties of the prepared IPNs were characterised using Fourier infrared spectroscopy (FT-IR), apparent crosslinking degree, thermal weight loss, mechanical properties, impact resistance and scanning electron microscopy (SEM). The study results showed that the conversion of DCPD did not change with the addition of PF. But when its content exceeds 10%, the crosslinking degree of PDCPD decreases. When the PF content is 10%, the maximum bending strength of PDCPD/PF IPNs is (104.5 ± 1.3) MPa, maximum tensile strength is (74.5 ± 1.4) MPa, and maximum-notched impact strength is (4.2 ± 0.2) kJ/m2. Compared with PDCPD, the bending strength is increased by 22.7%, tensile strength is increased by 32.6%, and notched impact strength is increased by 31.3%, but the thermal stability has no major impact at this time. PF has good dispersibility and compatibility in DCPD. Due to the interpenetrating network structure of PF and PDCPD, the interpenetrating interlocking of the PF molecular chain and PDCPD crosslinked network restricts its movement. Its performance reached the optimum, and the PDCPD/PF IPNs with excellent performance was successfully prepared.

Thioetherimide-Modified Cyanate Ester Resin with Better Molding Performance for Glass Fiber Reinforced Composites

Cyanate ester (CE) resins with higher heat resistance, lower coefficients of thermal expansion (CTEs), and lower water absorption ratios are highly desired in printed circuit boards (PCBs). In this work, a CE was modified by copolymerization with a long-chain thioether bismaleimide (SBMI) to form a thioetherimide-modified CE (SBT). The results indicated that SBT had a wider processing window and better processing properties than a common bismaleimide-modified CE resin (MBMI). After molding with a glass fiber cloth, the composites (GSBT) exhibited moisture adsorption in the range of 1.4%-2.0%, high tensile strength in the range of 311-439 MPa, good mechanical retention of 70%-85% even at 200 °C, and good dimension stability, with coefficients of thermal expansion in the range of 17.3-18.6 (×10-6 m/°C). Such GSBT composites with superior properties would be good candidates for PCB applications.