Advanced Materials Research Vol. 910

Abstract: Maleic anhydride grafted polypropylene (PP-g-MA) is used as a coupling agent, and the influence of its used amount on the mechanical properties of the polypropylene/short glass fiber (PP/SGF) composites is examined. 1, 2, and 3 wt% of PP-g-MA is separately added to PP/SGF composites that are made at an 80/20 ratio (wt%), made into pellets on a single screw extruder, and then made into test samples on an injection machine. When PP-g-MA increases from 1 wt% to 3 wt%, the tensile strength of the PP/SGF composites increases from 56.22 MPa to 64.85 MPa; likewise, flexural strength increases from 67.29 MPa to 81.24 MPa, and Izod impact strength increases from 197.70 J/m 269.61 J/m. SEM images show that the surface of SGF are encapsulated with a layer of PP matrix, which indicates that PP-g-MA can effectively improve the interfacial adhesion between PP and SGF and thus increase the mechanical properties of the resulting composites.

Abstract: In this study, high-resilience bonding polyester/Poly-paraphenylene terephthalamid intra-ply hybrid nonwovens with various fiber blending ratios and thermal treatment conditions were prepared through needle-punching and thermal bonding. The mechanical characteristics including tensile strength, tear strength, puncture resistance and bursting strength were investigated. The results showed that the addition of Kevlar fibers enhanced the mechanical properties of hybrid nonwovens. The tensile strength, puncture resistance and bursting strength also improved with the increase in thermal treatment duration and temperature while the tear strength had lower strength when treated at 180°C than at 170°C. The reason was thermal bonding points restricted the slippage of the fibers leading the fibers to break in sequence instead of sustaining the tension together.

Abstract: This paper reveals the manufacturing process and static impact resistance of sandwich structural hybrid laminates composed of high-resilience bonding polyester /Kevlar intra-ply hybrid nonwovens and E-glass woven fabric. The effects of various weight ratio of Kevlar fiber on the mechanical behaviors, including tensile strength, tear strength, bursting strength and puncture strength, were evaluated. The experimental results indicated that the tensile strength and fracture work were both enhanced with the increase in Kevlar content. The tear strength on CD and MD exhibited opposite trends when varying the Kevlar content. The static bursting and puncture resistances were both enhanced with the promotion of Kevlar content. The failure mechanisms of the breakages were also analyzed.

Abstract: In order to fabricate fabrics with electromagnetic shielding effectiveness (EMSE) and other function, we fabricated Crisscross-section polyester /antibacterial nylon / stainless steel wires (CSP/AN/SSW) composite yarns with stainless wires as core yarn, antibacterial nylon and crisscross-section polyester as inner and out wrapped yarns, respectively. Knitted fabrics were fabricated with the metal composite yarns with wrap amount of 8 turns/cm on a circular knitted machine. Furthermore, the EMSE of the metal composite fabrics were evaluated by changing the lamination amounts and lamination angles. The results show that when the lamination amount was four, lamination angles were 0°/45°/90°/-45°, the EMSE of the fabrics reached to-10--20 dB in the frequency range of 300 KHz to 3 GHz.

Abstract: Geotextile has been commonly used in civil and geotechnical engineering applications, and the majority of geotextiles is made of nonwoven fabrics. Therefore, this study combines crimped polyester (PET) fibers, recycled Kevlar unidirectional selvage fibers, and low-melting-point PET (LPET) fibers to form PET/Kevlar/LPET nonwoven geotextiles, and then examines how various neelde-punch depths influence mechanical properties of the resulting nonwoven geotextiles. The tensile strength, tearing strength, bursting strength, and static puncture resistance of the nonwoven fabrics increase as a result of an increase of 0.3 cm to 0.5 cm in needle-punch depth. However, an increase of 0.5 cm to 0.7 cm causes a slight decrease in all aforementioned properties.

Abstract: This study presents effects of foam density and vermiculite content of puncture resistance and cushion properties of PU/vermiculite foam composite for resisting against sharp objects and impact load. Results show that puncture resistance property improves significantly with foam density and slightly with increase of vermiculites. Cushion property becomes worse lower after vermiculite addition. With improvement of foam density, cushion property shows an uncertain trend. Besides, comparing with different contents of vermiculites, PU/vermiculite foam composite containing 5 wt% vermiculite has the lowest cushion property because vermiculite bonds with polar group among polar group among PU molecular.

Abstract: With the appearance of reticular tubes, coronary stents can resist the compressive strength caused by vascular pulsation. This study braids stainless steel fibers with diameters of 0.12 mm and 0.08 mm with a braiding technique, and the resulting braids are then combined with polyvinyl alcohol (PVA) solution to form three stent types-S12, PVA/S12, and PVA/S8. S12 is braids that are made of 0.12-mm-diameter stainless steel fibers, PVA/S12 is S12 coated with PVA. PVA/S8 is braids made with 0.08-mm-diameter stainless steel fibers and then coated with PVA. Surface, braiding angle, and compression behavior of the coronary stents are observed by a stereomicroscope, analyzed by Motic Images Plus 2.0 software, and examined by an Instron 5566, respectively. The experiment results show that compared to S12 and PVA/S8, PVA/S12 has a smaller braiding angle, indicating its manufacturing process is not stable. Of the three coronary stents, PVA/S8 possesses the greatest recovery from the compression, and thus this study yields optimal coronary stents with satisfactory surface, braiding angle, and recovery ability.

Abstract: Non-woven textile industry in an emerging field, with the process short, high yield, low cost and wide source of raw materials, but also has excellent performance of many functions on, making non-woven over the past half century gained textiles attention and consumers of all ages. The proportion of the world of non-woven fiber material used in the product, 85% in rayon ,and the other 15% in natural fibers, polyester fibers which accounted for the largest proportion of use. The experiment uses a low melting point polyester fiber (LPET) 20%, three-dimensional hollow curly polyester fiber (TPET) and recycled far infrared fiber (REPET) 40% each as the basic conditions change pressing temperature 100 °C-140 °C, in order to observe and compare the effects of temperature on the non-woven fabric, this experiment tests including air permeability, tensile strength testing, infrared testing and SEM, respectively in different hot pressing temperature, each of the non-woven hot pressing temperatures sample go through microscopic to analysis for non-woven with the hot temperatures strong reason to improve or decline with hot temperature of air permeability.

Abstract: Based on the obtained experimental results, the features of stress-strain behavior of the metallic foam were discussed firstly in this paper. Then, in the framework of 2M1C visco-plasticity constitutive model, a cyclic constitutive model was proposed to simulate the stress-strain responses under monotonic and cyclic compression. In proposed model, plastic strain is divided into two parts, i.e., plastic strain of matrix metal and plastic strain of voids structure, which are associated with relative density. Additionally, a kinematic hardening rule of yield surface center is used to describe ratchetting effect during cyclic loading. The simulated stress-strain responses of aluminum foam are in a good agreement with the experimental ones.

Abstract: Currently, researches on the gravity dam deep and shallow anti-sliding stability mainly focus on the analysis method and instability criterion, while the studies on specifically test the breakage of gravity dams due to weakening foundation rock mass and structural planes under loading are rare. Based on damage mechanics theory, this paper established a numerical model that analyzed the damage failure process of dam foundation rock mass. Taking two typical gravity dam models as the study objects, the damage processes of the dam foundations were simulated dynamically. Additionally, a comparison with other two traditional methods further validated the correctness and feasibility of the numerical model. In sum, the study findings point out that the numerical model is not only applicable to the study of the breakage mechanism of dam foundation rock mass, but also can be used as a new method to analyze problems related to deep anti-sliding stability of gravity dams.