Influence Of Short Fibers Research Articles

Stubble resistance of rubber vulcanizates: Influence of short fiber and resin

Stubble resistance of tread rubber vulcanizate of a tyre is crucial, especially for the off-the road (OTR) tyres. However, it has not been vividly discussed in the literature. Here, we developed a test method for stubble resistance, and studied the effect of short aramid fibre and two different types of resins on the stubble resistance of a conventional tire tread recipe with a view to its improvement. Resin filled compositions, being flexible, showed better cut initiation resistance, as compared to aramid fibre filled stiffer compositions, by dissipating the stress through chain orientation. During penetration, both cut growth and frictional force were important. For the aramid fibre composition, the frictional force dominated, whereas the cut growth was predominant for the resin filled vulcanizates. How the different energies associated with the fracture, e.g. cut initiation and growth energies, frictional energy and total fracture energy, altered with respect to the modulus or elongation at break of the rubber vulcanizates has also been discussed. At 4–6 phr of aramid filler concentration, stubble resistance drastically improved. On the other hand, the resin at 4 phr concentration exhibited an overall improvement in stubble resistance as compared to the conventional recipe. In summary, the present work contributed to the effect of different parameters on the stubble resistance of a tire tread rubber vulcanizate using an inhouse developed new test method.

Influence of Short Fiber- Reinforced Composites on Fracture Resistance of Single-Structure Restorations.

The aim was to determine the load-bearing capacity of anterior crowns prepared using two types of single-structure short fibre-reinforced composites (SFRCs). Furthermore, fracture toughness (FT), flexural strength (FS) and flexural modulus (FM) of tested composites were measured. Seven groups of composite crowns were designed for an upper central incisor (n=8/group). Two groups were CAD/CAM fabricated made of Cerasmart 270 and experimental single-structure SFRC blocks. Two groups were 3D-printed made of GC Temp PRINT and Pro3dure GR-17 composites. Two groups were made of conventional light-cured composites (Essentia and Gradia Plus). The last group was a single-structure SFRC made of commercial flowable SFRC (everX Flow). Crown restorations were loaded until fracture. Failure-modes were then visually examined. FT, FS and FM were determined for each tested composite (n=8). The data were analysed using analysis of variance (p=0.05) followed by Tukey's post-hoc test. ANOVA revealed that crowns made of experimental SFRC blocks had significantly higher load-bearing capacities (1650 ±230 N) (p⟨0.05) among all the groups tested. Experimental SFRC blocks exhibited the highest FT (2.9 MPa m1/2) and FS (245.8 MPa) values (p⟨0.05) among tested composites. CAD/CAM fabricated restorations made of experimental SFRC blocks demonstrated encouraging performance related to their fracture-behaviour.

Plane instability problem for a composite reinforced with a periodic row of short parallel fibers

The instability of a composite material reinforced with a periodic row of parallel short fibers is studied considering the interaction of neighboring fibers. Emphasis is on the mutual influence of short fibers in the matrix during loss of stability, depending on the distance between them. A piecewise-homogeneous medium model and the three-dimensional linearized theory of stability of deformable bodies are used

Investigation of the degradation of thermoplastic polyurethane reinforced with short fibres

The thermal behaviour of short fibre reinforced composites was studied by DSC and TGA techniques. A thermoplastic polyurethane elastomer was used as the matrix and carbon fibre or aramid fibre as reinforcing fillers in each composite. The influence of short fibres on the thermal resistance of the matrix, glass transition temperature and kinetic parameters of the degradation reaction of the composites were studied. The thermal resistance of aramid fibre reinforced composites was greater than those of carbon fibre reinforced composites or the pure matrix polymer. In addition to this, analysis of the kinetics and the glass transition temperature suggest greater interaction between aramid fibre and elastomer matrix.