Pham Quan Anh

Beverage bottle caps are usually made from two primary materials: PP and HDPE. In this study, the evaluation criteria were the unnotched impact toughness and the microstructure of PP/HDPE/EVA samples produced by injection molding. The samples were tested according to ASTM D256. PP/HDPE/EVA blends were prepared with various ratios: 47.5/47.5/5, 45/45/10, 42.5/42.5/15, 40/40/20, and 37.5/37.5/25. The results showed that adding EVA to the PP/HDPE blend significantly increased the unnotched impact toughness: from 84.03 kJ/m2 (PP/HDPE/5% EVA) to 85.06 kJ/m2 (PP/HDPE/10% EVA), then decreased to 70.3 kJ/m2 (PP/HDPE/15% EVA), followed by an increase to 83.32 kJ/m2 (PP/HDPE/20% EVA) and 89.42 kJ/m2 (PP/HDPE/25% EVA). The discrepancy in value between the samples with the highest and lowest EVA content was 19.12 kJ/m2. Overall, as the EVA content increased, the unnotched impact toughness also tended to increase. However, the sample with PP/HDPE/15% EVA showed a noticeable decrease.

This study investigates the impact of arc-hardening parameters on a groove-shaped S45C steel tube, with a focus on surface hardness and microstructure. According to the findings, when arc quenching occurs, the tube’s surface hardness increases significantly compared to its original hardness. The surface layer hardness can increase to 50.3 HRC, which is 3.4 times greater than the untreated surface. Changing arc quenching parameters such as current intensity, gas flow rate, arc length, scan speed, heating angle, and cooling angle causes a variation in surface hardness due to the balance of heat input and cooling value. Moreover, the microhardness distribution is divided into three zones: the hardened zone (with a high hardness value), the heat-affected zone (HAZ), which has rapidly declining hardness, and the base metal (with a low hardness value). The hardened zone could have a hardness with a load of 0.3 N of 440 HV and a case depth of about 900 μm. The next zone is the HAZ, where the hardness with a load of 0.3 N drops significantly. The hardness in the base metal zone recovers to its original value of 152 HV. Interestingly, the microstructure, under the hardness distribution, illustrates the relationship between the hardness value and its phases. The hardened zone consists of martensite and residual austenite phases, resulting in a high hardness value. The bainite phase constitutes the HAZ, which correlates to the zone of rapid hardness reduction. Finally, the base metal zone has ferrite and pearlite microstructures, indicating the softest zone. The investigation’s findings may increase our understanding of the arc-hardening process and widen its industrial applications.

Taguchi and post-heat treatment methods have been used in this study to optimize the metal inert gas (MIG) welding joints between SUS304 austenite stainless steel and plain carbon SS400 steel using AWS ER 308L filler wire. The dissimilar welding joints’ microstructure and tensile strength have been examined. The findings show that the fast cooling of the weld joint and the ferrite-forming element of the filler wire cause the dendrites’ δ-ferrite phase to emerge on both the weld bead and the heat-affected zone (HAZ) of the SUS304 side. The stickout parameter has the largest impact on the ultimate tensile strength (UTS), next to the welding speed, welding voltage, and welding current, due to the strong impact of the heat distribution. The optimal welding parameters are a welding current of 105 A, a welding voltage of 14.5 V, a stickout of 12 mm, and a welding speed of 420 mm/min, producing the UTS value of 445.3 MPa, which is close to the predicted value of 469.2 ± 53.6 MPa. Post-heat treatment with an annealing temperature that is lower than 700 °C could improve the optimized weld joints’ strength by up to 5%. The findings may provide a more realistic understanding of the dissimilar welding technology.

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This study analyzes the effect of glass fiber (GF) when mixed with a polybutylene terephthalate (PBT)/polyamide 6 (PA6) blend. In order to find a heat-insulating or fire-resistant material by adding GF to the PBT/PA6 mixture. This blend opens the potential to recycle many PBT and PA6 components of many toothbrushes. The PBT/PA6/GF mixture was prepared using the injection molding method with 0, 3, 6, 9, 12, 15, and 18% GF in the PBT/PA6 mixture at a 50/50 ratio. After injection molding, the samples were tested for the mixture’s impact toughness according to ASTM D256 standard. The result showed that, the impact toughness results corresponding to each ratio of 0, 3, 6, 9, 12, 15, and 18% are 22.23, 23.46, 23.76, 24.85, 25.39, 26.02, and 26.45 kJ/m². It can be seen that the PBT/PA6 sample reinforced with GF gives increasing measurement results through each ratio and the largest is the PBT/PA6 sample supported with 18% GF with a result of 30.64 MPa. The more GFs in the mixture, the better the results will be. Therefore, adding GF to PBT effectively enhances its tensile properties.

This study focuses on analyzing the influence of carbon black (CB) on Polybutylene terephthalate (PBT)/Polyamide 6 (PA6) blends. This study aims to solve the source of waste from toothbrush filament during production. This PBT/PA6 mixture does not meet the mechanical properties due to the incompatibility of these two plastics, which means this waste must be discarded and cannot be reused. When combined with CB, it creates a new type of plastic with more stable mechanical properties that can be applied in many areas of life and, at the same time, helps manufacturing businesses save on waste treatment costs. To create these PBT/PA6/CB blends, the research team used injection molding with a PBT/PA6 ratio of 75/25 combined with 0, 4, 8, and 12 % carbon black. The tensile and impact strength were tested according to the ASTM D638 and ASTM D256 standards. The results found that when adding 4 % CB to the PBT/PA6 plastic mixture, the tensile strength decreased from 34.9 to 34.8 MPa. Meanwhile, the tensile strength is improved when adding 8 % CB (35.3 MPa). At 12 % CB, a difference in tensile strength results, decreasing to 29.7 MPa. This result shows that the ratio 75/25 can give the best tensile strength value of the PBT/PA6 mixture with 8 wt. % CB. The impact strength was 3.5, 2.9, and 2.7 kJ/m2 according to 4, 8, and 12 % CB samples. Mechanical quality tests have shown that the tensile strength is improved when combining CB into the PBT/PA6 mixture, but the impact strength is reduced. SEM results show that most CB interacts with PBT/PA6 mainly because the PA6 particles are spherical and tend to separate easily from the mixture. The research found that increasing CB density worsens the bonding ability between PBT and PA6. These results help us provide experience for the most appropriate application for each purpose Це дослідження зосереджено на аналізі впливу сажі на суміші полібутилентерефталату (ПБТ)/поліаміду 6 (ПА6). Це дослідження спрямоване на виявлення джерела відходів від нитки зубної щітки під час виробництва. Ця суміш ПБТ/ПA6 не відповідає механічним властивостям через несумісність цих двох пластмас, що означає, що ці відходи потрібно викинути та не можна використовувати повторно. У поєднанні із сажею він створює новий тип пластику з більш стабільними механічними властивостями, який можна застосовувати в багатьох сферах життя, і, в той же час, допомагає виробничим підприємствам заощаджувати витрати на переробку відходів. Для створення цих сумішей ПБТ/ПA6/сажа дослідницька група використовувала лиття під тиском із співвідношенням ПБТ/ПA6 75/25 у поєднанні з 0, 4, 8 та 12 % сажі. Міцність на розтягування та ударну міцність перевіряли відповідно до стандартів ASTM D638 та ASTM D256. Результати показали, що при додаванні 4 % сажі до пластикової суміші ПБТ/ПA6 міцність на розрив зменшилася з 34,9 до 34,8 МПа. Між тим, міцність на розрив покращується при додаванні 8 % сажі (35,3 МПа). При 12 % сажі виникає різниця в міцності на розрив, яка зменшується до 29,7 МПа. Цей результат показує, що співвідношення 75/25 може дати найкраще значення міцності на розрив суміші ПБТ/ПA6 з 8 мас. % сажі. Ударна в’язкість становила 3,5, 2,9 і 2,7 кДж/м2 за зразками 4, 8 і 12 % сажі. Механічні випробування якості показали, що міцність на розрив покращується при поєднанні сажі із сумішшю ПБТ/ПA6, але міцність на удар знижується. Результати скінченно-елементного моделювання показують, що більшість сажі взаємодіє з ПБТ/ПA6 головним чином через те, що частинки ПА6 мають сферичну форму та мають тенденцію легко відокремлюватися від суміші. Дослідження показали, що збільшення щільності сажі погіршує зв’язок між ПБТ і ПA6. Ці результати допомагають отримати досвід для найбільш відповідного застосування для кожної мети