Physico-Mechanical,Interfacial, Degradation,and Dielectric Properties of Jute/PP Composites: Effect of Dye and Gamma Radiation

Jute fabrics/polypropylene composites were prepared by compression molding. Jute fabrics were treated with red dye solutions (0.1–1%, w/w) for different soaking times and we found that 0.5% red-dye-treated jute/PP composite for 5 min soaking time showed better results. Gamma radiation (250-1000 krad dose) was applied on both jute and matrices. Composites were fabricated with non-irradiated jute/non-irradiated PP (C-0), non-irradiated jute/irradiated PP (C-1), irradiated jute/non-irradiated PP (C-2), and irradiated jute/irradiated PP (C-3). It was found that a C-3 composite made using 500 krad dose showed the best results. Simulating weathering and dielectric properties of the composites were also performed.     

A Comparative Study on the Mechanical,Degradation and Interfacial Properties of Jute/LLDPE and Jute/Natural Rubber Composites

Jute fabric (hessian cloth) reinforced low-density polyethylene (LLDPE) composites (40 wt%) and solid natural rubber-(NR) based composites (40 wt%) were fabricated by compression molding. Tensile strength (TS), tensile modulus (TM) and percentage elongation at break (Eb) of jute/LLDPE composites were found to be 29, 680 MPa and 20%, and for jute/NR-based composites were also found to be 15, 122 MPa and 94%, respectively. Interfacial shear strength (IFSS) of the jute/LLDPE and jute/NR systems was investigated by using the single fiber fragmentation test (SFFT). Scanning electron microscopy (SEM) and aqueous degradation tests were also performed.     

Fabrication and Mechanical Characterization of Jute Fabrics: Reinforced Polyvinyl Chloride/Polypropylene Hybrid Composites

Jute fabrics such as reinforced polyvinyl chloride (PVC), polypropylene (PP), and a mixture of PVC and PP matrices-based composites (50 wt% fiber) were prepared by compression molding. Tensile strength (TS), bending strength (BS), tensile modulus (TM), and vbending modulus (BM) of jute fabrics' reinforced PVC composite (50 wt% fiber) were found to be 45 MPa, 52 MPa, 0.8 GPa, and 1.1 GPa, respectively. The effect of incorporation of PP on the mechanical properties of jute fabrics' reinforced PVC composites was studied. It was found that the mixture of 60% PP and 40% PVC matrices based composite showed the best performance. TS, BS, TM, and BM for this composite were found to be 65 MPa, 70 MPa, 1.42 GPa, and 1.8 GPa, respectively. Degradation tests of the composites for up to six months were performed in a soil medium. Thermo-mechanical properties of the composites were also studied.     

Comparative Studies on the Mechanical,Degradation and Interfacial Properties between Jute and E-Glass Fiber-Reinforced PET Composites

Jute fiber mat (hessian cloth) reinforced PET-based composites (50% fiber by weight) and E-glass fiber matreinforced PET based composites (50% fiber by weight) were fabricated by compression molding and the mechanical properties tensile strength (TS), tensile modulus (TM), elongation at break (%), bending strength (BS), bending modulus (BM), impact strength (IS) and hardness (Shore-A) of the composites were evaluated and compared. The interfacial properties of the both composites were also compared. Water uptake test and soil degradation test were also investigated.     

Effect of Ultraviolet Radiation and Potassium Permanganate on the Physico-Mechanical Properties of Jute Polymer Composites

Jute fabrics-reinforced polymer composites were prepared with different formulations using oligomer (M-1200), methanol and benzoyl peroxide. Fiber content in the composites was optimized and 55% jute content at oligomer: methanol: benzyl peroxide = 75:24.5:0.5 (w/w) ratios showed better mechanical properties. Jute fabrics were treated with potassium permanganate (KMnO₄) solution of different concentrations for different soaking times. Optimized jute fabrics were soaked in the optimized formulation (F3) and cured under UV radiation at different intensities and measured their mechanical properties. Scanning electron microscopy (SEM), water uptake and soil degradation test of the treated and untreated composite samples were performed.     

Surface Modification of Jute Fabrics Using Acrylic Monomers: Effect of Additives

Jute fabrics were modified with methyl acrylate (MA), ethyl acrylate (EA), and 2-hydroxyethyl acrylate (2-HEA) using UV radiation at different periods of time. It was found that 30% MA at 60 min, 15% EA at 40 min, and 15% 2-HEA at 15 min irradiation time in methanol along with photoinitiator showed the best results. Some additives, such as urea, acrylamide (AM), ethylhexyl acrylate (EHA), tripropelene glycol diacrylate (TPGDA), and trimethylol propane triacrylate (TMPTA), were incorporated into the optimized monomer solutions and monitored its effect on the properties. Various physico-mechanical properties of both treated and untreated jute fabrics were also performed.     

Comparative Studies of Mechanical and Interfacial Properties Between Jute Fiber/PVC and E-Glass Fiber/PVC Composites

Composites (50 wt% fiber) of jute fiber reinforced polyvinyl chloride (PVC) matrix and E-glass fiber reinforced PVC matrix were prepared by compression molding. Mechanical properties such as tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM) and impact strength (IS) of both types of composites was evaluated and compared. Values of TS, TM, BS, BM and IS of jute fiber/PVC composites were found to be 45 MPa, 802 MPa, 46 MPa, 850 MPa and 24 kJ/m², respectively. It was observed that TS, TM, BS, BM and IS of E-glass fiber/PVC composites were found to increase by 44, 80, 47, 92 and 37.5%, respectively. Thermal properties of the composites were also carried out, which revealed that thermal stability of E-glass fiber/PVC system was higher. The interfacial adhesion between the fibers (jute and E-glass) and matrix was studied by means of critical fiber length and interfacial shear strength that were measured by single fiber fragmentation test. Fracture sides after flexural testing of both types of the composites were investigated by Scanning Electron Microscopy.     

Mechanical and Electrical Properties of Jute Fabrics Reinforced Polyethylene/Polypropylene Composites: Role of Gamma Radiation

Jute fabrics reinforced polyethylene (PE), polypropylene (PP) and mixture of PP+PE matrices based composites (50 wt% fiber) were prepared by compression molding. It was found that the mixture of 80% PP + 20% PE hybrid matrices based jute fabrics reinforced composites performed the best results. Gamma radiation (250–1000 krad) was applied on PP, PE and jute fabrics then composites were fabricated. The mechanical properties of the irradiated composites (500 krad) were found to increase significantly compared to that of the non irradiated composites. Electrical properties like dielectric constant, loss tangent and conductivity with temperature variation of the composites were studied.     

汽车内饰用PP/黄麻纤维复合材料力学性能

采用转矩流变仪混合造粒,通过注射成型方法制备了聚丙烯(PP)/黄麻纤维复合材料,研究了对纤维表面进行处理的NaOH浓度、纤维含量和相容剂的含量对PP/黄麻纤维复合材料力学性能的影响,采用扫描电镜对纤维表面及复合材料的断面形貌进行分析。结果表明:黄麻纤维经过碱处理后PP/黄麻纤维复合材料的力学性能优于纤维未处理的复合材料的力学性能,随着NaOH浓度的提高,PP/黄麻纤维复合材料的拉伸强度和冲击强度增加,在NaOH浓度为16%时,其拉伸强度和冲击强度最佳;其弯曲强度随着NaOH浓度的提高先增加而后下降,在8%浓度时,弯曲强度最大。随着纤维含量的提高,PP/黄麻纤维复合材料的拉伸强度和弯曲强度先增加后下降,在纤维含量达到20%时,PP/黄麻纤维合材料的拉伸强度和弯曲强度达到最大。随着纤维含量的提高,PP/黄麻纤维复合材料的冲击强度降低。相容剂的加入使得PP/黄麻纤维复合材料的拉伸强度和弯曲强度明显增加。     

Studies on the Physicomechanical Properties of Sodium Periodate Oxidized Jute Reinforced Polypropylene (PP) Composites

In the present work, effects of oxidation and fiber content (from 20 to 35 wt. %) on the physicomechanical properties of jute-polypropylene (PP) composites were studied. Mechanical properties (tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus, and charpy impact strength) were measured for all raw and oxidized jute-PP composites. Improved mechanical properties were obtained for oxidized jute-PP composites. Interfacial adhesion and bonding between the fiber and PP matrix were investigated by scanning electron micrograph analysis. Improved interfacial interactions and reduced water absorption were found for oxidized jute-PP composites. Water absorption tests of all composites were also performed.     

Effects of Surface Pretreatment on the Mechanical and Dielectric Properties of Photocuring Jute Fibers

Jute fabrics were treated with ethylene glycol dimethylacrylate (EGDMA) + MeOH solutions at different proportions along with photoinitiator Irgacure 907 and cured under UV-radiation. Monomer concentration, soaking time, and radiation dose were optimized in terms of polymer loading and mechanical properties. Twenty-five percent EGDMA, 30-minute soaking time, and tenth-pass of radiation produced higher tensile strength (75%) and tensile modulus (88%) than those of the untreated sample, as well as the highest polymer loading value (70%). Among different additives used, urea showed the best performance. SEM, water uptake, and dielectric properties of the samples were studied.     

Improvement of Mechanical Properties of Jute Fibers-Polyethylene/Polypropylene Composites: Effect of Green Dye and UV Radiation

Jute-reinforced polyethylene (PE), polypropylene (PP) and mixture of PP/PE composites were prepared. It was found that 90% PP and 10% PE matrices based jute reinforced composites performed the better results. UV radiation at different intensities was applied both on matrices and jute. Mechanical properties of the irradiated jute- and matrices-based composites were found to increase significantly. Optimized jute fabrics were also treated with different concentrations of green dye (0.1–1%, w/w) with 2% K₂O₈S₂ in methanol solution for 2–8 min. A composite made of 0.5% green dye jute (5 min soaking time) and irradiated matrix showed the best mechanical properties.     

竹粉/PVC发泡复合材料的制备与性能研究

采用模压法制备了竹粉/聚氯乙烯(PVC)发泡复合材料,研究了邻苯二甲酸二辛酯(DOP)、发泡剂偶氮二甲酰胺(AC)、竹粉、成核剂及成型压力对复合材料密度和力学性能的影响。结果表明:添加DOP使复合材料密度和拉伸强度下降,断裂伸长率快速增大;AC发泡剂用量增加,复合材料密度减小;竹粉用量增加,复合材料密度增加,力学性能变差;纳米二氧化钛和轻质碳酸钙的添加能有效改善复合材料的性能,其最佳用量为2份;复合材料最佳成型压力为6 MPa。     

Effect of Wood Fibers on the Rheological and Mechanical Properties of Polystyrene/Wood Composites

The effects of wood fibers on the rheological and mechanical properties of polystyrene/wood (PS/wood) composites were investigated. The composites with different ratios of PS and wood were prepared by means of internal mixer and, additionally, two different sizes of the wood particles were used, such as ～100 and ～600 µm. The rheological properties were studied using capillary rheometer, apparent shear rate, apparent shear stress, apparent viscosity, power law index, and flow activation energy at a constant shear stress were determined. The rheological results showed that the shear stress–shear rate variations obeyed a power law equation, and the composites exhibited shear thinning. The flow activation energy of the composites increased with the addition of wood particles. Mechanical results showed that stress at break of the composites was higher than that of pure PS, whereas the strain at break and impact strength of the composites were lower than that of PS. In addition, the mechanical properties of the present composites were improved when the small size of wood particles were incorporated.     

纤维类型对C/SiC复合材料性能的影响

利用化学气相浸渗法制备了Cf-C/SiC复合材料,借助SEM、TEM等研究了纤维类型对Cf-C/SiC复合材料力学性能的影响.实验证明T300碳纤维增韧补强效果优于M40碳纤维,利用T300碳纤维制备出弯曲强度为459M,断裂韧性为20.0MPa*m1/2,断裂功为25170J/m2的Cf-C/SiC复合材料.2种碳纤维增韧效果的差异是由纤维的原始强度、热膨胀系数和弹性常数的不同决定的.     

Synthesis, Properties, and Oxidation of Alumina-Titanium Nitride Composites

Al₂O₃-TiN composites varying from 60 to 66.6 mol% TiN were prepared by an in situ reaction between TiO₂ and AlN. N₂ or O₂ evolution takes place, depending on the composition selected. A pseudobrookite (PB) phase appears in the reaction product, the amount decreasing as the TiO₂:AlN ratio becomes poor in AlN. The in situ reaction product can be pressureless sintered to 94% to 97% theoretical density at 1600°C in N₂. The four-point flexural strength varies from 280 to 430 MPa at room temperature. The fracture toughness is 3 to 4.7 MPa.m^1/2. Oxidation of a 94% dense TiN-Al₂O₃ composite in the temperature range 710° to 1050°C was also studied. A layer of TiO₂ (rutile) protects the composite at 710°C from further oxidation with a weight gain of 0.08 mg/cm² in 90 min. In the temperature range 820° to 1050°C, the initial oxidation kinetics are parabolic, with an activation energy of 216.5 kJ/mol. Linear oxidation kinetics with an activation energy of 113.7 kJ/mol pertain at longer times.     

Mullite/Alumina Particulate Composites by Infiltration Processing: III, Mechanical Properties

The effect of incorporating mullite into alumina by an infiltration process on the mechanical properties was investigated. Data for Young's modulus, strength, and fracture toughness for various composite compositions were compared with those for the unreinforced matrix (alumina). Measurements of Young's modulus by a resonance technique showed that the addition of mullite decreased Young's modulus. Up to 14 vol%, these changes were close to those expected, but above this mullite content, the decrease was more dramatic and indicated specimen damage during processing. The addition of mullite led, in some cases, to increases of more than 60% in both the strength (biaxial flexure) and indentation fracture toughness. These increases have been attributed to the method of introducing mullite and the resulting residual compressive surface stresses. The strength of the indented composite bodies deviated from the ideal behavior, indicating the probability of R -curve behavior in these materials.     

汽车内饰用酚醛树脂/黄麻纤维复合材料的拉伸性能

采用正交试验方法,用5%Na OH溶液对黄麻毡进行预处理,利用模压成型工艺制备酚醛树脂/黄麻纤维复合材料,通过对正交试验结果进行极差分析和方差分析,研究树脂含量、模具温度、模具压力和保压时间4个工艺参数对复合材料拉伸性能的影响程度和显著性水平,并通过多指标综合评分法对材料的拉伸性能综合评价,分析各个工艺参数对材料拉伸性能的影响规律。结果显示,树脂含量和模具压力对复合材料的拉伸性能影响非常显著,当树脂含量为20%、模具温度为180℃、模具压力为10 MPa、模压时间为6 min时,复合材料的拉伸性能最好,此时拉伸强度为24.06 MPa,拉伸弹性模量为113.17 MPa。     

Lignin Epoxy Composites: Preparation,Morphology, and Mechanical Properties

A novel route to lignin epoxy composites is developed through covalent incorporation of depolymerized lignin epoxide into amine‐cured epoxy matrix. The partially depolymerized lignin is first epoxidized with epichlorohydrin and the resultant depolymerized lignin epoxide shows decreased solubility in common organic solvents. When dispersed in epoxy matrix and cured, the depolymerized lignin epoxide is integrated into epoxy networks in the form of submicron aggregates. The resulting lignin epoxy composites show improved mechanical properties compared with neat epoxy. At a loading content of 1.0 wt% of degraded lignin epoxide, the Young's modulus and the critical stress intensity factor (K_IC) of the composite increase by 10% and 25%, respectively, in comparison with those of neat epoxy, while the glass transition temperature is little changed. This method presents a promising way to convert wasteful lignin to an alternative epoxy monomer and effective additive in epoxy composites.

     

碳纤维/聚合物自润滑复合材料的机械及摩擦性能

采用以钢铁为基体高分子自润滑复合材料为衬层制作的传动件,兼有优良的减磨耐磨性能和高的承载能力。研究了组分对复合材料性能的影响,制备了机械和摩擦学性能好的碳纤维增强复合材料,其黏结强度和压缩强度分别达到16~18 MPa和85~91 MPa,冲击强度达19.67~23.45 kJ/m2;与锡青铜ZQSn6-6-3摩擦对比试验表明,复合材料在重载工况下具有更优良的摩擦性能,工作状况稳定,油摩擦因数为0.077,仅为ZQSn6-6-3的59%。试验还发现,轻载启动和在摩擦面开设润滑油槽有助于改善摩擦状况。