Frontal polymerization
has been explored as a technique to form two-dimensional thin films
(<0.5 mm) on wood. We used trimethylolpropane triacrylate with
a thermal free-radical initiator. The viscosity of the resin was adjusted
by incorporating fumed silica within the formulation. As filler materials,
either calcium carbonate or graphene nanoplatelets was used to evaluate
the effect of filler type and content on front propagation. We observed
that resin viscosity and film thickness critically affected the qualitative
and quantitative propagation of the thermal front resulting in the
formation of the coating. A workable coating was formed at a viscosity
of 0.6 Pa·s, which was obtained when 3 phr (parts per hundred
resin) of fumed silica was used in the resin formulation. Wet film
thickness for this resin system was also found to have a limiting
value, and full propagation of the front to result in a conformal
coating required at least 15 mil (1 mil = 25 μm) of wet film
thickness. Filler materials affected film propagation as a function
of particle size and thermal properties. While 15 phr calcium carbonate
could be incorporated with the resin, only 5 phr graphene nanoplatelets
could be loaded within the matrix to ensure complete propagation of
the front. Interestingly, for graphene fronts, velocity and temperature
reduced systematically as a function of filler content. Filler type
and content affected porosity and roughness of the coating, which
was quantified by computerized tomography to understand the relationship
between porosity and adhesion of the coated film with the wood substrate.
A single intervention may not fulfil all feeding requirements of infants with CLCP. Combined use of different feeding interventions such as palatal obturator, Haberman feeder, and breast milk pump and lactation education may successfully meet the feeding needs of both mother and child.
Aim:
The aim is to compare and evaluate the different finishing and polishing systems for the change in surface roughness of resin composites and enamel.
Materials and Methods:
To conduct the study, 30 extracted human maxillary central incisors were selected, decoronated, and molded in self-cure acrylic molds. A box-shaped cavity of dimensions 3 mm × 3 mm × 2 mm was prepared in all the teeth. A nanohybrid composite resin (Filtek Z250) was then used to restore the prepared cavities. Thirty samples were divided into two groups, control group (Group A,
n
= 10) and experimental group (Group B,
n
= 20). The samples in Group A were cured through the Mylar matrix. The experimental group, i.e., Group B was divided into two subgroups, i.e., Subgroup BX,
n
= 10 in which Sof-Lex polishing system was used for polishing the tooth surface and Subgroup BF,
n
= 10 in which Shofu composite polishing system was used. The mean surface roughness (Ra in μm) of the composite restoration as well as for the enamel surface of all the samples before and after polishing was measured with a contact profilometer, and the values were correlated with scanning electron microscopy.
Results:
The statistical analysis was carried out using paired
t
-test. The results exhibited a significant decrease in the surface roughness of the resin composite and enamel surface irrespective of the finishing and polishing system used. The mean surface roughness values demonstrated by Mylar matrix was the lowest followed by Sof-Lex polishing system. Shofu polishing system demonstrated the highest surface roughness values.
Conclusion:
Finishing and polishing of composite restoration can achieve a surface roughness similar to that of enamel. Involvement of marginal enamel in finishing and polishing procedures carried out for composite restoration results in smoother enamel surface.
We studied self-assembly and colloidal properties of poly(ethylene glycol) (pEG) conjugated sucrose soyate polyols (PSSP). These molecular platforms were synthesized by covalently connecting PEGs of different molecular weights (M n ) (12 and 16 ethylene oxide units) to epoxidized sucrose soyate (ESS). The synthesized PSSP products showed amphiphilicity, reduced water surface tension, and exhibited critical Aggregation Concentration (CAC) within the range of 0.3−0.4 mg/mL. We observed that PSSP self-assembles in water in the form of nanoparticles without the need of any cosolvents. These nanoparticles exhibited numberaverage hydrodynamic diameter of 120 ± 8 nm with a polydispersity index (PDI) of <0.3, and negatively charged surfaces. We also found out that PSSP nanoparticles can encapsulate and homogeneously distribute a hydrophobic model compound, such as a phthalocyanine dye, Solvent Blue-70 (BL-70), on a metal surface. Collectively, our studies explored and demonstrated the possibility of molecular diversification of biobased starting materials to form amphiphilic nanoparticles with industrially relevant colloidal and surface properties.
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