Degree of conversion and molecular weight of one denture base and three reline resins submitted to post-polymerization treatments

Abstract

The effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of three reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and one denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long), was evaluated by using FT-Raman spectroscopy (n = 5). The molecular weight (Mw) of the powder of all materials and of K polymerized specimens (control; MW; and WB; n = 3) was analyzed using GPC. DC data were analyzed using Kruskal-Wallis test (a = .05). For control specimens, there were no significant differences between U (68%) and LL (77%) and among LL, K (81%), and T (84%). LS (92%) had the highest DC (P < 0.05). Only material K exhibited an increased DC after WB (P < 0.05). All powders had Mw from 4.0 x 10(5) to 6.5 x 10(5) and narrow Mw distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with Mw similar to that of K powder

Chlorhexidine-loaded functionalized mesoporous MCM-41 poly(methylmethacrylate) based composites with Candida antibiofilm activity

“…The DC of monomer-to-polymer was calculated by comparison of the absorbance ratio using a standard baseline technique of the C = C peak from the methacrylate group at 1640 cm -1 and to that of the unchanging C = O peak from the ester group at 1720 cm -1 , which was used as a reference peak, before and after polymerization 28,29 . The DC % was determined by the following formula:…”

Study the FTIR of Hydroxyapatite Additive to Heat Cured Acrylic Resin

“…The degree of conversion of the materials under investigation was determined by Fourier transform infrared spectroscopy (FTIR) thirty six specimens of heat polymerizing resin with dimension of 10x4x4(±0.03)mm were prepared, and divided into three groups (First group Control, Second group with HA 2%, Third group with HA 5%) after that the specimens were finished with stone bur and sand paper to remove any gypsum product on their surfaces then they polished and stored in distilled water at 37(±1)C for 48 hours (2) . After 48 hours, the specimens were removed from water and dried in air and then scraped using a sharp, clean and sterile wax knife to obtain powder of the polymerized specimens.…”

“…conversion of monomer into polymer is not completed. The degree of conversion is the most important criterion that account for un reacted residual monomer levelsP (1) P .The final degree of conversion of a resin depends on the chemical structure of the dimethylmethacrylate monomer and the polymerization conditions i.e., atmosphere, temperature, light intensity and photo initiator concen-trationP (2) P . The degree of conversion is expressed as percentage of un reacted C=C bondsP (3) P .…”

EVALUATION OF A NEWLY FORMULATED AUTOPOLYMERIZED ACRYLIC RESIN PERMANENT DENTURE BASE MATERIAL (In Vitro Study)

“…Each specimen studied by this device gave us an Infra-Red chart which shows peaks, the range of spectrum used between 4000cm -1 at high frequency and 650cm -1 at low frequency. The Degree of Conversion (DC) (%) of monomer-topolymer was calculated by comparison of the absorbance ratio using a standard baseline technique of the C = C peak from the methacrylate group at 1640 cm -1 to that of the unchanging C = O peak from the ester group at 1720 cm -1 , which was used as a reference peak, before (monomer) and after polymerization (19).…”