Synthesis of diepoxycyclohexylethyl tetramethyldisiloxane and its application to stereolithography 3D printing

Purpose The purpose of this study is to synthesize a new kind of a cationic-type UV-curing prepolymer diepoxycyclohexylethyl tetramethyldisiloxane, which is used to replace the current prepolymers’ common cycloaliphatic epoxy resins to prepare a novel 3D printing stereolithography material. Design/methodology/approach Diepoxycyclohexylethyl tetramethyldisiloxane was characterized and analyzed by FT-IR and 1HMR. Diepoxycyclohexylethyl tetramethyldisiloxane was compounded with a polycaprolactone polyol, some acrylates and photoinitiators to prepare a novel 3D printing stereolithography resin (3DPSLR11). Optical properties of 3DPSLR11 were investigated by HRPL-150A stereolithography apparatus and INITELLI-RAY400 UV-curing system. Tensile mechanical properties of printed 3DPSLR11 specimens were tested by WDW-50-type universal testing machine, and the glass transition temperature (Tg) was determined by DMA. Rectangle plates and double-cantilever parts were fabricated by using the stereolithography apparatus with 3DPSLR11 as the printing material, and the dimension shrinkage factors and the curl factors of the parts were investigated. Findings The experimental results showed that the critical exposure (Ec) of the 3D printing 3DPSLR11 was 11.6 mJ/cm2, its penetration depth (Dp) was 0.18 mm, the tensile strength of the cured 3DPSLR11 was 40.1 MPa, the tensile modulus was 1,741.4 MPa, the elongation at break was 15.3%, Tg was 113°C, the dimension shrinkage factor was less than 0.85% and the curl factor was less than 8.00%. Originality/value In this work, a novel 3D printing 3DPSLR11 was prepared with diepoxycyclohexylethyl tetramethyldisiloxane as a main prepolymer. The novel 3DPSLR11 possessed excellent photosensitivity, and its cured products had good mechanical and thermal properties. The accuracy and resolution of the fabricated parts were high with 3DPSLR11 for stereolithography in 3D printing, which showed that 3DPSLR11 has potential application value as 3D printing material.

Thermal Conductive Composites Prepared by Addition of Several Ceramic Fillers to Thermally Cationic Curing Cycloaliphatic Epoxy Resins

Novel composite coatings prepared from 3,4-epoxy cyclohexylmethyl 3,4-epoxycyclohexane carboxylate (ECC) and different ceramic fillers have been prepared to improve the thermal dissipation of electronic devices. As latent cationic initiator, a benzylanilinium salt with triethanolamine has been used, which leads to a polyether matrix. Different proportions of Al2O3, AlN and SiC as fillers were added to the reactive formulation. The effect of the fillers selected and their proportions on the evolution of the curing was studied by calorimetry and rheometry. The thermal conductivity, thermal stability, thermal expansion coefficient and thermomechanical and mechanical properties of the composites were evaluated. An improvement of 820% in thermal conductivity in reference to the neat material was reached with a 75 wt % of AlN, whereas glass transition temperatures higher than 200 °C were determined in all the composites.

Synthesis and properties of cycloaliphatic epoxy resins containing imide and diphenyl sulfone

A novel variety of cycloaliphatic epoxy resins containing imide and diphenyl sulfone (named as 4,4′-bis[4-(4,5-epoxy-1,2,3,6-tetrahydro-phthalimido) phenoxy] diphenyl sulfone, BIES) is designed and synthesized through the three-step procedure. The mixtures of BIES and diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate (TDE-85) are cured with methyl tetrahydrophthalic anhydride. Fourier transform infrared spectrum and proton nuclear magnetic resonance spectrum confirm that the BIES contains the chemical structure of imide and diphenyl sulfone. The measurements of glass transition temperature ( Tg), heat distortion temperature (HDT), and the 5% weight loss temperature ( T5%) show that the co-cured BIES/TDE-85 exhibits excellent heat resistance. For the BIES/TDE-85 with mass ratio of 0.2, Tg, HDT, and T5% of the co-cured epoxy are 175°C, 162°C, and 290°C, respectively. The impact strength increases from 117 J m−1 to 139 J m−1 with the increasing of the mass ratios of the BIES/TDE-85 from 0 to 0.2.