In Situ Modification of Aramid Pulp With Poly(Methyl Methacrylate) via Supercritical Carbon Dioxide Technique for Enhanced Composite Properties

The interfacial adhesion and dispersion of aramid pulp (AP) in poly(methyl methacrylate) (PMMA) denture base materials were enhanced by developing a supercritical carbon dioxide (scCO 2 )-assisted in situ polymerization method. To enhance the fiber–matrix compatibility and dispersion in PMMA, methyl methacrylate (MMA) was grafted onto the AP surfaces in a scCO 2 media. Results of SEM revealed that modified AP has a uniform dispersion in the PMMA composite with strong interfacial bonding. When the treated AP content was 5 wt%, the hardness of the composite was 66.00 HRC, an increase of 28% compared to the untreated AP/PMMA. The volume wear rate decreased to 1.4 mm 3 Nm −1 , representing an 83.3% reduction compared to pure PMMA, which indicated an improved wear resistance indicating an improvement in wear resistance. When the treated AP was 2 wt%, the flexural strength was 166.49 MPa, 50.52% higher than that of the PMMA composites with untreated AP, the tensile strength was 56.39 MPa, 50.52% higher that of the PMMA composites with untreated AP. Thermomechanical properties of the AP/PMMA composites conducted from the DMA results showed the storage modulus increased, but the glass translation temperature did not change. These results demonstrate that the modification of the AP assisted by scCO 2 in situ radical-initiated polymerization has certain advantages in PMMA reinforcement. Highlights Interfacial adhesion was enhanced by in situ modification of aramid pulp (AP) with MMA in scCO 2 . Modified AP has a uniform dispersion in PMMA. Wear resistance of the PMMA composites with modified AP was improved. Storage modulus of the composites improved.