高强聚丙烯腈碳纤维复丝拉伸强度的测试

以东丽T700SC-12K碳纤维为样品,详细研究了碳纤维复丝拉伸测试过程中影响制样的因素,主要包括环境温度和湿度、胶液配比、浸胶时间、加强片以及样条和加强片固化温度。结果表明:随湿度增加,碳纤维拉伸强度下降;配置胶液时需选择合适的配比;浸胶时间长短对碳纤维拉伸强度影响不大;加强片厚度选择要适中;样条和加强片固化温度高会造成碳纤维拉伸性能的下降。     

Estimation of tensile strength of inorganic plate‐like particulate reinforced polymer composites

The reinforcing mechanisms of inorganic plate‐like particulate reinforced polymer composites were discussed based on the micro‐mechanical model in this article, and a new expression of tensile strength was derived by introducing an interfacial strength factor. This equation was applied to estimate the tensile strength of inorganic plate‐like particulate reinforced polymer composites. The results showed that the relative tensile strength increased nonlinearly with increasing filler volume fraction. Finally, the equation was verified preliminarily using the measured tensile strength of the mica reinforced poly (aryl ether ketone) composites and mica reinforced polydimethylsiloxane networks reported from literature, good agreement was found between the predictions of the relative tensile strength and the experimental data. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Tensile strength of agglomerates

Firstly, this paper gives a review of tensile strength of agglomerates; i.e. a discussion of the most important theoretical considerations, the various methods of measurement, a comparison of measuring techniques by experimental results and a brief look at deformation behaviour under unidirectional loading. In the second part new developments are dealt with.For the tensile strength of agglomerates in which forces are transmitted at points of contact, a new relationship is shown in which the displacements due to individual forces are taken into consideration. Experiments in which not only the tensile strength but also the force distribution are measured demonstrate the necessity of the new approach when short-range forces are present. However, the force—displacement characteristics of the attractive forces need not to be taken into account when long-range forces — e.g forces due to suitability large liquid bridges — act. The attractive forces may then be linearly superposed.The measurement of the tensile strength of agglomerates is discussed in detail. In particular the problematic nature of measurements using the split plate apparatus is pointed out, and a new method of interpreting results is suggested. The applicability of this method is tested by comparable experiments.     

A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials

A novel indirect tensile test method, the biaxial flexure test (BFT) method, has been developed to measure the biaxial tensile strength of concretes. The classical modulus of rupture (MOR) test has been generalized to three dimensions. In this method, we use a circular plate as the new test specimen. This plate is supported by an annular ring. We apply an external load to this specimen through a circular edge. The centers of the specimen, the loading device and the support are identical. The biaxial tensile strength measured by this new method is about 19% greater than the uniaxial tensile strength obtained from the classical modulus of rupture test as reported by other researchers. However, at the same time, we also found that the stochastic deviation of the biaxial tensile strength is about 63% greater than the uniaxial strength.     

Mechanical properties and miscibility of polyethersulfone/phenoxy blends

The blends of polyethersulfone and phenoxy were prepared by melt mixing in a Brabenderlike apparatus. The specimens for measurements were made by compression molding and then were water-quenched at room temperature under pressure. The tensile strength, tensile modulus, elongation at break and yield, density, thermal analysis, and dynamic mechanical properties were each measured. The dependence of tensile strength, tensile modulus, elongation at break and yield, and density on composition was obtained. The relationship between tensile modulus and elongation at break and yield and speed of the crosshead at different weight ratios of the blends is shown. The effects of composition and miscibility on the mechanical properties are discussed. © 1996 John Wiley & Sons, Inc.     

Preliminary investigation of poly(ether sulfone)/poly(aryl ether ketone) containing 1,4‐naphthalene blends

The blends of poly(ether sulfone) and poly(aryl ether ketone) containing 1,4‐naphthalene were prepared by melt mixing in a Brabender‐like apparatus. The specimens for measurements were made by compression molding under pressure and then were water‐quenched at room temperature. The tensile strength, tensile modulus, elongation at break, thermal analysis, and scanning electron microscopy were each measured. The dependence of tensile strength, tensile modulus, and elongation at break on blend systems was obtained. The effects of composition and miscibility on the mechanical properties are discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 472–476, 2006     

Tribological testing of peroxide cured HNBR with different MWCNT and silica contents under dry sliding and rolling conditions against steel

The sliding, and rolling friction and wear behaviors of peroxide cured hydrogenated nitrile rubber (HNBR) with 10 and 30 parts per hundred rubber (phr) multiwall carbon nanotube (MWCNT) and silica, respectively, were investigated. Mechanical properties (hardness, tensile modulus, ultimate tensile strength and strain, tear strength) of the rubbers were determined. Dynamic-mechanical thermal analysis was also performed and the apparent crosslink density estimated. Tribological properties were investigated in pin (steel)-on-plate (rubber), with roller (steel)-on-plate (rubber), with oscillating steel cylinder on rubber plate (Fretting) and with rolling ball (steel)-on-plate (rubber) (RBOP) test configurations. Coefficient of friction and specific wear rate (Ws) of the HNBR systems were determined. It was established that the resistance to wear increases with increasing filler content, and the incorporation of MWCNT was more advantageous than silica from the viewpoint of dry sliding and rolling performance. The friction and wear characteristics strongly depended on the test configurations. The worn surface of the HNBR systems was inspected in scanning electron microscope to conclude the typical wear mechanisms which were discussed accordingly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

大孔径聚四氟乙烯筛板的加工及应用

采用聚四氟乙烯(PTFE)车削板为原料,机械加工生产大孔径PTFE筛板,对筛板与车削板进行了拉伸性能分析。结果表明,随筛板孔距的增加,其拉伸强度、拉伸屈服应力及拉伸断裂应力均提高;随筛板孔径的增大,其拉伸强度、拉伸屈服应力及拉伸断裂应力均降低。试验发现,厚度为0.40mm、孔型(孔径×孔距)为1.5mm×1.5mm及厚度为0.50mm、孔型为1.5mm×1.5mm及2.0mm×2.0mm三种型号筛板的拉伸性能优良,透氨性能好,适合oce655、oce642S、Admiral AD及QU和DH-9916B型等多种型号的高速晒图机使用。     

Fracture failure processes in polymers. I: Mechanical tests and results

Tensile tests and Izod impact tests were carried out on eight thermoplastics and an epoxy. The results are compared with shear strengths determined previously, and it is shown that for seven of the polymers, the nominal tensile strength is equal to the yield strength and is approximately the same as the shear strength measured by the punch test. (The true ultimate tensile strength is not always a useful concept because the more ductile polymers are radically changed during the tensile testing process.) In shear tests the shear strains can be extremely high before eventual failure. Because of this the Iosipescu test appears to be unsuitable for measuring the ultimate shear strengths of polymers. Classical shear sliding of failure appears to be rare, and instead most of the polymers appear to be failing in tension when tested in the punch test. (Shear is equivalent to tension at +45° and compression at ?45° to the shear directions.) The polymers with shear Strengths that are significantly less than the tensile strengths are brittle ones, and these differences are probably due to flaw statistics. Thus the idea first advanced to explain unduly high interface shear strengths in centrosymmetric systems, i.e., that most polymers ultimately fail in tension when tested in shear, appears to be validated.     

Increasing the strength and toughness of a carbon fiber/silicon carbide composite by heat treatment

The effect of heat treatment on the strengthening and toughening of a carbon fiber/silicon carbide composite (C/SiC) with a thin pyrolytic carbon (PyC) interphase was investigated. Tensile strength and modulus were measured using tensile tests, and toughness was obtained by calculating the area under the stress–strain curves. Results show that with increasing heat treatment temperature both the strength and toughness of the C/SiC composite increased, but the modulus decreased. After heat treatment at 1900 °C the tensile strength and toughness increased by a maximum of 42% and 252%, respectively, and the modulus decreased by 48%. X-ray diffraction analysis and microstructural observation confirmed that the heat treatment mainly increased the graphitization of the amorphous PyC interphase, and this was responsible for the property changes observed because it decreased the interfacial sliding resistance associated with long fiber pull-out, relieved the thermal residual stress and lower stress concentrations on the fibers to uniformly share the load for improving the strength and toughness.     

Silicon Carbide Ceramic Particulate Reinforced AA2024 Alloy Composite - Part I: Evaluation of Mechanical and Sliding Tribology Performance

In this research work, a master batch (comprising of AA2024 alloy, Silicon Nitride (Si3N4) and Graphite particulates) was reinforced by Silicon-Carbide (SiC) ceramic particulates (0–6 wt.-%; at steps of 2%; i.e. four composites samples viz. ASC-0; ASC-2; ASC-4; ASC-6) with the aim of enhancing mechanical and sliding tribology performance. The semi-automatic stir-casting fabrication process was followed as per standard industrial practice in-order-to fabricate the sample plates of the said alloy composites as per design. Thereafter, the sample specimens were prepared via wire EDM cutting followed by polishing over emery paper; as per ASTM standard dimensions and various physical (density and void content), mechanical (tensile strength, flexural strength, impact strength, hardness etc.), sliding tribology performance (steady state sliding wear; ASTM G-99; Pin-on-Disc tribo-meter), thermal (thermal conductivity, Thermo-Gravimetric Analysis (TGA)); thermo-mechanical (Dynamic Mechanical Analysis (DMA)), fracture-analysis, X-ray diffraction (XRD) etc. characterisation were performed and discussed. In Part-1: Physical, mechanical and sliding tribology performances were discussed. The Taguchi design of experiment technique was employed for designing of experimental runs having input controlling parameters like sliding velocity (0.654–2.616 m/s), sliding distance (784.8–3139.2 m), normal load (5–50 N), reinforcement content (0–6 wt.-%) and environment temperature (20–50 °C). The worn surface morphology studies were performed to understand prevalent wear mechanism using Field Emission Scanning Electron Microscope (FESEM) along with Energy-dispersive X-ray spectroscopy (EDS) that reveals elemental composition and its dispersion on the surface. In Part-2: evaluation of characterizations like thermal, thermo-mechanical, fracture-analysis, X-ray diffraction (XRD) etc. were discussed in correlation with mechanical and sliding wear performance. In Part-3: the entire performance data are analysed using hybrid AHP-TOPSIS technique (an MCDM technique; computationally simple and easy to understand) in-order-to rank the composites formulations.     

Durability of glass‐fiber‐reinforced polymer composites in an alkaline environment

This study investigated the aging of urethane and urethane‐modified vinyl ester (UMVE) GFRPs (glass fiber reinforced polymers) when they were exposed to alkaline solution for six months under a sustained load of 34.5 MPa or 16–20% of their tensile strength. The second experiment exposed both types of GFRP to alkaline solution without load for 6 months. The final experiment determined the alkaline solution diffusion coefficients into GFRP and neat polymer resin samples by measuring the change in mass of each sample as a function of time. After the GFRP samples were aged for 6 months, their tensile strengths were measured and compared with that of non‐aged samples to determine the aging effect. It was found that alkaline solution alone without sustained load did not significantly reduce or change the tensile strength of any GFRP sample. However, the presence of sustained load greatly increased the aging effect, particularly more for urethane GFRP than on UMVE GFRP. Urethane GFRP experienced a tensile strength reduction of 57.5%, while UMVE GFRP lost 27.3% of its original tensile strength. J. VINYL ADDIT. TECHNOL., 13:221–228, 2007. © 2007 Society of Plastics Engineers     

Determination of mechanical properties of glass‐epoxy composites in high temperatures

The objective of this study is to determine the tensile, compressive, and shear properties of unidirectional glass/epoxy composite plates under room (∼20°C) and high (40, 60, 80, and 100°C) temperatures. Mechanical properties were determined according to the ASTM standards. A hot lamination press was used for fabrication of composite plates. For curing process, laminated plates were retained at a constant pressure (250 kPa) and 120°C during 2 h. And then, composite plate is cooled to room temperature at the same pressure. The fiber volume fraction of laminated composite plate is measured as 65%. Experimental results show that the mechanical properties (except for the transverse tensile strength) of glass/epoxy composites are reduced by increasing temperature. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

The Internal Tensile Strength of a Borosilicate Glass Determined from Laser Shock Experiments and Computational Analysis

It is of interest to determine the internal tensile strength of glass because it is used in material models to understand and design transparent armor. It is difficult to determine this strength because surface conditions limit the ability to apply large tensile stresses needed to cause internally located crack initiation. This article presents a novel approach to estimate the internal tensile strength of glass using a combination of laser shock experiments and computational analysis. Laser shock produces a unique loading condition that causes maximum tension to occur in the interior of the glass without destroying the target. Several laser shock experiments were performed on a plate of borosilicate glass at varying levels of peak pressure. In one experiment, damage was produced only in the interior of the plate (there was no damage on either the front or rear surfaces). This experiment was singled out for analysis because surface flaws did not influence the internal crack initiation event. Computational analysis indicated that the internal tensile strength of this borosilicate glass is approximately 1.2 GPa. The computed results produced damage only in the interior of the glass plate, similar to experimental observation. A similar failure stress was obtained using the Griffith criterion.     

Nitrile rubber/sliding graft copolymer damping material with significantly improved strength and damping performance

Nitrile rubber (NBR)/sliding graft copolymer (SGC) composites with significantly improved strength and damping property are successfully prepared. SGC is a novel kind of supramolecular material with sliding crosslink junctions. The micromorphology analyses of NBR/SGC composites indicate that the SGC phase with particle size less than 500 nm is fairly uniformly dispersed in the NBR matrix. As SGC content increases, the loss factors (tan δ) of NBR/SGC composites increase gradually. Specifically, the tan δ of NBR/SGC (100/40) is about 1.2 times higher than that of pristine NBR rubber. The tensile strength and elongation at break of NBR/SGC composites are unexpectedly improved after the addition of SGC. The significantly improved damping performance and tensile strength can be ascribed to the pulley effect of SGC and the strong interfacial hydrogen bonds between SGC and NBR. The high damping performance and good mechanical strength make the NBR/SGC composite a promising high-performance damping material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47188.     

PVC/锯末塑木材料的研制

以锯末和PVC胶粘剂为主要原料，用高速混合机制备了PVC／锯末塑木材料，并通过平板硫化机热压成型，制备出了新型的PVC／锯末塑木板材；测试了塑木板材的拉伸强度，弯曲强度，冲击强度，拉伸弹性模具，弯曲弹性模量等力学性能，讨论了增塑剂和胶粘剂用量对塑木板材性能的影响，实验结果表明：随增塑剂用量的增大，PVC／锯末塑木板材的刚性下降，韧性升高；随胶粘剂用量的增大，PVC／锯末塑木板材的力学性能和耐水性均有提高。     

含有纳米蒙脱土的HIPS的制备与性能研究

究含纳米蒙脱土的高抗冲聚苯乙烯(HIPS)的制备工艺,测试了试样的冲击强度和拉伸强度等力学性能,观察了试样冲击断面的结构形态。结果表明,在PS中加入少量蒙脱土和橡胶弹性体制备的HIPS冲击强度为16．2kJ／m^2,拉伸强度为46．6MPa,断裂伸长率为1．62％,已接近或达到工程塑料的使用要求。原因是纳米蒙脱土粒子在橡胶微粒界面上富集,使两者产生了协同改性效应。     

粉磨改性重质碳酸钙及其在PVC硬板中的应用

利用一种新型ＳＭ－１０搅拌磨作为粉碎ＣａＣＯ３的粉磨机械，并用自制复合活化剂作为研磨助剂和偶联剂，在将ＣａＣＯ３磨成超细粉的同时，利用复合活化剂即时活化改性。然后把经活化的ＣａＣＯ３填充到超高分子量ＰＶＣ中，实验结果表明：试样缺口冲击强度大于７ｋＪ／ｍ＾２，当ＣａＣＯ３填充量为７０质量份时，拉伸强度大于２０ＭＰａ，实验讨论了ＳＭ－１０搅拌磨粉磨工艺和ＰＶＣ硬板压制了工艺及增塑剂用量，复合活化剂用量     

Orientation in amorphous polymers I. Preparation and testing of oriented samples

Orientation effects in amorphous polystyrene are studied using a uniaxial stretching experiment. The rheological properties of the polymer are determined from an analysis of creep data obtained from the tensile apparatus, and oriented polymer samples are prepared at different extension ratios and rates of stretching. From birefringence and tensile strength measurements on oriented samples of polystyrene, it is shown that the tensile strength is not a unique function of the birefringence. It is proposed that the tensile strength may depend not only on the average orientation, as reflected by the birefringence, but on which portion of the relaxation spectrum is preferentially oriented.     

Polyrotaxane-modified waterborne polyurethane based on H-bonding and metal bonding with mechanically tough and self-healability

The pulley structure has been widely employed to improve mechanical properties. Polyrotaxane-based waterborne polyurethane (WPU) typically exhibits good tensile strength and Young's modulus. However, achieving outstanding self-healability of polyrotaxane-based WPU under mild conditions generally proves insufficient solely relying on host-guest interactions. Herein, a strategy that constructs a triple synergy of host-guest interaction, hydrogen bonds, and metal coordination bonds by sequentially introducing tannic acid (TA) and Fe³⁺ is proposed to prepare polyrotaxane-based WPU with excellent mechanical performance and high self-healable capability. Besides the reversible non-covalent bonding contributing to intrinsic self-healing, the unique sliding motion of WPU's molecule chain acts as a driving force, promoting efficient contact among reversible bonds. Notably, benefiting from the sliding motion of β-cyclodextrin (β-CD) along a chain, the dynamic reconstruction of hydrogen bonds and metal coordination bonds, the resulting supramolecular WPU exhibited a tensile strength of 46.05 MPa and a toughness of 130.30 MPa, with satisfactory self-healing performance (tensile strength healing efficiency of more than 95%). This work enriches the self-healing mechanism and expands the concepts for the design of resilient self-healing environmentally friendly supramolecular WPU.