Tensile Strength Of Sheet Research Articles

Influences of amine/epoxide ratio on cross-linking structure and mechanical properties of cured hydrogenated epoxy resin sheets and single-lap joints

The influence of the amine/epoxide ratio (N–H/Ep.), controlled from 0.5 to 2.0, on the network structure and mechanical properties of cured epoxy resin (CER) was investigated using a cycloaliphatic epoxy and amine components, in a form of sheets and single-lap joints (SLJs). The cross-linking density and glass transition temperature of CER sheet was the highest at 1:1 stoichiometric N–H/Ep. ratio and became lower with being out of the ratio. On the contrary, tensile strength of sheet and shear strength of SLJ monotonically increased and decreased with an increase in amine content, respectively. Excess amine can work as fillers for sheets and made interfacial strength weaken between adherend and adhesive for SLJs. Changing the N–H/Ep. ratio can control the mechanical properties of not only sheets, but SLJs. Comparisons with mechanical properties of sheets and SLJs are quite helpful to design the high-performance adhesive.

A quasi-2D exploration of optimum design settings for geotextile-reinforced sand in assistance with PIV analysis of failure mechanism

Many earlier studies were focused on testing different types of geosynthetics to investigate effect of reinforcement on bearing capacity, but the effect of tensile strength on the failure mechanism has not been examined sufficiently. Within this scope, a test setup was prepared to apply strip loads on densely compacted reinforced sand under the plane strain condition. The tank containing the reinforced sand was a rectangular prism with perfect transparency, and its interior dimensions were 960 × 200 × 650 mm3. Firstly, optimum values of design variables (depth of first sheet, length and number of sheets, space between sheets, tensile strength of sheets) for the woven geotextile reinforced sand were determined experimentally. Then, the failure mechanisms of the soil, which were reinforced with geotextiles of different tensile strengths, were observed and analyzed with particle image velocimetry (PIV) technique. Consequently, the failure mechanism of the sand with a single geotextile reinforcement was similar to general shear failure of unreinforced soil. Contrarily, the failure surfaces were deeper and longer. Additionally, the deep-footing mechanism reached out large depth in the case of four reinforcement layers. The failure mechanism converted into a punching type due to a hypothetic increase in the bearing depth of reinforcement.

Study of Refining Effect of Mixed Pulps Using Refiner Plates with Different Bar Patterns

A new lightweight vertical bar plate was developed by inserting individual bars into the plate base rather than the typical sand casting method. The lightweight vertical bar plate has a very sharp bar edge because vertical bars are inserted instead of trapezoidal bars. The refining effects of the mixed stock with softwood bleached kraft pulp (Sw-BKP) and hardwood bleached kraft pulp (Hw-BKP) were compared using two types of lightweight vertical bar plates with cutting edge lengths of 55 km/s (PA55) and 97 km/s (PB97). The fine bar plate (PB97) with large CEL (PB97) was very effective in reducing the refining energy required to reach the final freeness regardless of the mixing ratios of Sw-BKP and Hw-BKP compared to the plate with a small CEL (PA55). PB97 also consumed less refining energy than PA55 until proper sheet strength was achieved. In particular, irrespective of the mixing ratios of Sw-BKP and Hw-BKP, the tensile strength of sheets at the final freeness was greater in PB97 than in PA55. For stock throughput during refining, PA55 with the wide groove was almost similar to PB97 with the narrow groove.

Effects of addition method and fibrillation degree of cellulose nanofibrils on furnish drainability and paper properties

The objectives of this work were to investigate the effect of the degree of fibrillation and addition method of cellulose nanofibrils (CNFs) into the wet end of the papermaking process on the drainage, filler retention, strength and optical properties of handsheets. CNFs were produced with the grinding method, and the degree of fibrillation was manipulated by varying the passing number through the grinder from 15 to 50 passes. The CNFs were added to the wet end of the papermaking process in two different ways: a precipitated calcium carbonate (PCC)-CNF composite filler and a wet-end additive. The results showed that the water retention capacity of CNFs increased as the fibrillation was performed, and this resulted in an increase in drainage time. The solid content of handsheets filled with composite filler was about 1–2% higher than in the CNF-added sheets after wet pressing. Furthermore, the composite filler-filled sheets with higher ash content had similar tensile strength, compared with the CNF-added sheets. It was also found that water retention capacity of CNFs increased as the fibrillation was performed, and this resulted in an increment in drainage time and a reduction in solid content of sheets after wet pressing. The more fibrillated CNFs significantly (p < 0.05) increased the density and tensile strength of sheets, which might be due to the increased number of inter-fiber bonds. Filler retention and opacity were not significantly influenced by the fibrillation degree of CNFs.

Relationship between wettability and sizing degree of paper containing bulking agent

The addition of a bulking agent achieves the bulking of paper and increases the pore volume. In this study, the effect of adding bulking agents with various alkyl chain lengths (C14, C18, and C22) on the bulk of paper, the sizing performance, and sheet wettability was evaluated. The bulking effect of a bulking agent with a short alkyl chain length (C14) was large, and reduction in the sheet tensile strength was confirmed to be suppressed. Good sheet sizing performance was achieved when a bulking agent was used with an alkyl ketene dimer (AKD). When 0.1% or more of AKD was added, using a bulking agent with a shorter alkyl chain length increased the improvement in the sizing degree. Pyrolysis gas chromatography measurements of the amount of reacted AKD revealed that the addition of a bulking agent increased the AKD content of the sheet. The sheet contact angle measured by the two-liquid method tended to increase with increasing alkyl chain length. However, the sheet contact angle was not directly correlated with the Stockigt sizing degree. By using 1% ferric chloride (FeCl3) and 2% ammonium thiocyanate (NH4SCN) aqueous solution, which are used for measuring the Stockigt sizing degree, the time-dependent change in the contact angle on the paper sheet surface was measured to evaluate wettability. The Stockigt sizing degree of paper sheets was found to be greatly influenced by the sheet wettability by NH4SCN solution. In the case of 2% NH4SCN aqueous solution, different samples exhibited large wettability differences. When 0.2% or less of AKD was added, the effect of the concentration on the contact angle was confirmed to be large at all NH4SCN concentrations.

The Effects of Temperature and Roll Pressing on the Properties of iPP Sheets

By using a processing of gas-cooling and roll pressing (GCRP), the temperature, strain and stress of isotactic polypropylene (iPP) sheets can be controlled and both β-modification and α-modification can be found in the sheets. The tensile strength of sheet in longitudinal direction increased by 14.1% at most, tensile modulus 14.2%, flexural strength 50.3% and impact strength 22.2%. Therefore, the strength and toughness of iPP can be increased simultaneously by GCRP.