Flame retardancy,Thermal and mechanical properties of Kenaf fiber reinforced Unsaturated polyester/Phenolic composite

Unsaturated polyester (UP) resin has been blended with phenolic resin (PF) resole type at various ratios to obtain a homogeneous blend with improved flame resistance compared to its parent polymers. The polymer blend was reinforced with 20 wt% kenaf using hand lay out technique. Fourier transform infrared spectroscopy (FT-IR) was used to characterize changes in the chemical structure of the synthesized composites. The thermal properties of the composites were investigated using thermogravimetric analysis (TGA). The thermal stability of UP/PF kenaf composites co-varies with the PF content, as shown by the degradation temperature at 50 % weight loss. The char yield of the composites increases linearly with PF content as shown by the TGA results. The flammability properties of the composites were determined using the limiting oxygen index (LOI) and UL-94 fire tests. The LOI increased with the PF content while the composites exhibit improved flame retardancy as demonstrated by UL-94 test. The mechanical and morphological properties of the composites were determined by tensile test and scanning electron microscopy (SEM), respectively. The tensile strength and the Young’s modulus of the blend/composites slightly decreased with increasing PF content albeit higher than PF/kenaf fiber composites.     

Preparation and properties of fumed silica/Kevlar composite fabrics for application of stab resistant material

The objective of this study is to develop an advanced stab proof material composed of shear thickening fluid (STF) and Kevlar fabric. In this study, silica/ethylene glycol suspension was prepared for the use as the STF, and it was analyzed by a rheometer, TEM and dynamic light scattering spectrophotometer. From the results, it was observed that the STF significantly showed the reversible liquid-solid transition at a certain shear rate. Also, we treated Kevlar plain fabric with the STF by 1 dip-1nip finishing method and investigated the mechanical and stab resistant properties. Through the investigation of the fumed silica/Kevlar composite fabric, we found that the STF impregnation significantly improved the stab resistance of Kevlar fabric against spike threats and so enhance the protection performance of Kevlar fabric as a stab proof material.     

Coir fiber reinforced polypropylene composite panel for automotive interior applications

In this study, physical, mechanical, and flammability properties of coconut fiber reinforced polypropylene (PP) composite panels were evaluated. Four levels of the coir fiber content (40, 50, 60, and 70 % based on the composition by weight) were mixed with the PP powder and a coupling agent, 3 wt % maleic anhydride grafted PP (MAPP) powder. The water resistance and the internal bond strength of the composites were negatively influenced by increasing coir fiber content. However, the flexural strength, the tensile strength, and the hardness of the composites improved with increasing the coir fiber content up to 60 wt %. The flame retardancy of the composites improved with increasing coir fiber content. The results suggest that an optimal composite panel formulation for automotive interior applications is a mixture of 60 wt % coir fiber, 37 wt % PP powder, and 3 wt % MAPP.     

Hybrid multi-scale basalt fiber-epoxy composite laminate reinforced with Electrospun polyurethane nanofibers containing carbon nanotubes

In this study, we report the fabrication and evaluation of a hybrid multi-scale basalt fiber/epoxy composite laminate reinforced with layers of electrospun carbon nanotube/polyurethane (CNT/PU) nanofibers. Electrospun polyurethane mats containing 1, 3 and 5 wt% carbon nanotubes (CNTs) were interleaved between layers of basalt fibers laminated with epoxy through vacuum-assisted resin transfer molding (VARTM) process. The strength and stiffness of composites for each configuration were tested by tensile and flexural tests, and SEM analysis was conducted to observe the morphology of the composites. The results showed increase in tensile strength (4–13 %) and tensile modulus (6–20 %), and also increase in flexural strength (6.5–17.3 %) and stiffness of the hybrid composites with the increase of CNT content in PU nanofibers. The use of surfactant to disperse CNTs in the electrospun PU reinforcement resulted to the highest increase in both tensile and flexural properties, which is attributed to the homogeneous dispersion of CNTs in the PU nanofibers and the high surface area of the nanofibers themselves. Here, the use of multi-scale reinforcement fillers with good and homogeneous dispersion for epoxy-based laminates showed increased mechanical performance of the hybrid composite laminates.     

Thermal stability and physical properties of epoxy composite reinforced with silane treated basalt fiber

This study evaluates the influence of different silane coupling agents on the thermal and physical properties of epoxy-anhydride composite reinforced with basalt fiber. The silane coupling agents were selected by their functional groups so that they could have different chemical interactions with the epoxy and anhydride curing agents. The thermal and degradation behavior of the composites with different fiber contents were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Through the evaluation of T _g and thermal degradation behavior of both systems, it was deduced that the silane coupling agents have a great influence on the thermal properties of the composites as well as interfacial improvement. Also, the tensile properties of the composites were systematically evaluated in order to further understand the effect of silane coupling agents on the interaction with basalt fiber and epoxy matrix.     

熟黄(红)麻木质素标准试验方法研究

阐述了熟黄(红)麻木质素标准试验方法研究的必要性,同时对该方法涉及的技术特点及其主要参数、精密度、线性范围、检出限与加标回收率等进行了系统研究。其结果为制订行业标准——《熟黄(红)麻木质素测定硫酸法》奠定了坚实基础。     

Investigations on mechanical characteristics of glass fiber reinforced epoxy composite modified with amino-terminated hyperbranched polymer

Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism.     

亚麻屑和红麻芯用于仙客来栽培基质的研究初报

为提高亚麻屑和红麻芯的附加值,促进生物资源的综合利用,分别用25%、50%、75%与100%的亚麻屑和红麻芯替代普通泥炭作为仙客来栽培基质.结果表明用25%的亚麻屑或50%的红麻芯替代普通泥炭均有利于仙客来的生长与开花,其各项指标均优于常规基质.     

亚麻屑和红麻芯用于仙客来栽培基质的研究初报

为提高亚麻屑和红麻芯的附加值，促进生物资源的综合利用，分别用25％、50％、75％与100％的亚麻屑和红麻芯替代普通泥炭作为仙客来栽培基质。结果表明：用25％的亚麻屑或50％的红麻芯替代普通泥炭均有利于仙客来的生长与开花，其各项指标均优于常规基质。     

The cocoyam,Xanthosoma sagittifollium,as a potential raw material source for beer brewing

A widely cultivated cocoyam variety,Xanthosoma sagittifollium, was assessed for its suitability for lager beer production, using maltedSorghum vulgare (white variety) for saccharification of the substrate. The three-mash decoction method was used. Results showed that the cocoyam was superior to barley and sorghum as a substrate because of its potentially higher carbohydrate content (71–78%) compared to barley (65%) and sorghum (70–73%). The percentage wort extract was 13.3–14.5° plato compared to 7–12 for barley and 13° for the tuber crop, cassava. The kiln driedXanthosoma sagittifollium gave a dark bager beer with good aroma (68%) and very good flavour (73%) when compared with a commercial lager beer (Monarch) as standard (100%). The alcohol content (4.16% w/v) and the specific gravity (1013) were within the range (4.0–6.4%) and (1011–1019), respectively, specified by the Standard Organization of Nigeria. Although the bitterness value 40 EBU, was higher than the typical range 16–30 EBU, the taste panel indicated this was acceptable. The pH was 4.68 compared with the standard 4.36, while the acidity (as % lactic acid) was 0.36 compared to 0.24 for some commercial products.     

1999—2000年全国红麻新品种(系)区域试验总结

“九     

2004-2006年全国红麻新品种(组合)联合区域试验总结

本届全国红麻新品种(组合)区域试验于2004～2006年分别在安徽六安、河南信阳等7省(区)的7个区试点进行,参试品种(组合)共计8个,由中国农业科学院麻类研究所等国内四家麻类育种科研单位提供。通过对所有参试品种3年7点的田间试验鉴定与室内检测数据进行统计分析,重点对影响参试品种纤维产量性状的相关变异来源进行了LSD法测验及适应性参数的估算,并结合其主要农艺性状、生物学特性、抗逆性、纤维品质、生育期等方面进行了综合分析与评价。     

麻杆粉代料栽培香菇的技术研究

在实验研究的基础上,成功地进行了红麻杆代料栽培香菇的生产试验.试验结果表明,麻杆粉代替木屑栽培香菇是完全可行的,但出菇后期营养不足、容易散袋,导致出菇期短,产量低.改善培养的营养成份,增强料袋的紧实度,提高保水性能,可使菌丝生长快,香菇产量高,花菇率高.培养料中木屑含量在20%左右时,香菇产量最高,效益最佳.     

麻杆粉代料栽培香菇的技术研究

在实验研究的基础上，成功地进行了红麻杆代料栽培香菇的生产试验。试验结果表明，麻杆粉代替木屑栽培香菇是完全可行的，但出菇后期营养不足、容易散袋，导致出菇期短，产量低。改善培养的营养成份，增强料袋的紧实度，提高保水性能，可使菌丝生长快，香菇产量高，花菇率高。培养料中木屑含量在20％左右时，香菇产量最高，效益最佳。     

Study of moisture and thermal transfer properties as a function of the fiber material variation

The properties of moisture transfer and the comfort of mesh-structured fabrics with various knit compositions and properties were investigated. The comfort effects of the double knitted fabrics combined with different cross-shaped fibers composed of dyeable-polypropylene (PPd) and regular polyester (PET) double-knitted fabrics were studied. A series of PET, PPd, Coolmax^® (Cm) with single knitted fabrics and PPd/Cm with double knitted fabrics were evaluated to determine the physical properties and wearing performance for comfortable clothing. To compare the structural properties involving the vapor transfer of 4 types of fabrics with different fiber compositions, fiber types, weights, and thicknesses, the surface structure and pore characteristics were evaluated by scanning electron microscopy and a capillary flow porometer. The properties of moisture transfer were tested using vertical wicking and gravimetric absorbent testing system (GATS). In addition, the comfort performance measured by the thermal insulation value (Rt) and moisture permeability index (im) with a thermal manikin in a conditioned walk-in environmental test chamber was predicted. The result showed that the PPd/Cm sample has potential applications as good comfort fabric materials.     

Hybrid effect in the mechanical properties of jute/rockwool hybrid fibres reinforced phenol formaldehyde composites

This research work was concerned with the evaluation of the effect of fibre content on the mechanical properties of composites. Composites were fabricated using jute/phenol formaldehyde (PF), rockwool/PF, and jute/rockwool hybrid PF with varying fibre loadings. Jute and rockwool fibre reinforced PF composites were fabricated with varying fibre loadings (16, 25, 34, 42, 50, and 60 vol.%). The jute/rockwool hybrid PF composites were manufactured at various ratios of jute/rockwool fibres such as 1:0, 0.92:0.08, 0.82:0.18, 0.70:0.30, 0.54:0.46, 0.28:0.72, and 0:1. Total fibre content of the hybrid composites was 42 vol.%. The results showed that tensile strength of the composite increased with increasing fibre content up to 42 vol.% over which it decreased for jute and rockwool fibre reinforced PF composites. Flexural strength of the composite was noted to peak at a fibre loading of 42 vol.% for jute/PF composites, and 34 vol.% for rockwool/PF composites. Impact strength of jute/PF composites increased with increasing fibre loading but that of rockwool/PF composites decreased at higher (>34 vol.%) fibre loadings. Tensile, flexural, and impact strengths of jute/PF composites were found to be higher than those of rockwool/PF composites. The maximum hardness values were obtained 42 vol.% for jute/PF composite, and 34 vol.% for rockwool/PF composite. Further increase in fibre loading adversely affected the hardness of both composites. For jute/rockwool hybrid PF composites, tensile and impact strengths decreased with increasing rockwool fibre loading. The maximum flexural strength of jute/rockwool hybrid PF composites was obtained at a 0.82:0.18 jute/rockwool fibre ratio while maximum hardness was observed at a 0.28:0.72 jute/rockwool fibre ratio. The fractured surfaces of the composites were analysed using scanning electron microscope in order to have an insight into the failure mechanism and fibre/matrix interface adhesion.     

黄、红麻束纤维断裂强力测定值正态性检验与取舍

运用SPSS13.0统计分析软件与夏皮罗-威尔克(Shapiro-Wilk)法对黄、红麻束纤维断裂强力检测数据分布特征进行了分析,结果表明其分布近似正态分布,检测数据可按置信概率P=0.99时,正常值Fi∈(F-2.58S,F+2.58S)进行取舍.     

Synthesis,structure and thermal protective behavior of silica aerogel/PET nonwoven fiber composite

In recent years, flexible, mechanically strong and environmental friendly thermal insulation materials have attracted considerable attention. In this work, silica aerogel/polyethylene terephthalate (PET) nonwoven fiber composite with desirable characteristics was prepared via a two-step sol-gel process followed by an ambient drying method through immersing the PET nonwoven fiber into silica sol. The silica aerogel particles were characterized by FTIR, FE-SEM, TGA and nitrogen adsorption analysis. The morphology and hydrophobic properties of neat PET nonwoven fiber and its silica aerogel composite were also investigated. For studying thermal protective properties, the thermal diffusivity was calculated from temperature distribution curves. The mean pore size of 11 nm, the surface area of 606 m²/g and the total pore volume of 1.77 cm³/g for the silica aerogel particles in the composite are obtained from nitrogen adsorption analysis, indicating the aerogel can maintain its high porosity in the nonwoven composite structure. Silica aerogel particles were efficiently covered the surface of the PET fibers and completely filled the micron size pores of the nonwoven fiber leading to a stronger hydrophobicity and higher thermal insulation performance in the aerogel composite samples compared to the neat PET nonwoven. In this regard, an almost 64 % decrease in the thermal diffusivity was achieved with 66 wt% silica aerogel.     

Effect of the low and radio frequency oxygen plasma treatment of jute fiber on mechanical properties of jute fiber/polyester composite

We investigated the surface modification of jute fiber by oxygen plasma treatments. Jute fibers were treated in different plasma reactors (radio frequency “RF” and low frequency “LF” plasma reactors) using O₂ for different plasma powers to increase the interface adhesion between jute fiber and polyester matrix. The influence of various plasma reactors on mechanical properties of jute fiber-reinforced polyester composites was reported. Tensile, flexure, short beam shear tests were used to determine the mechanical properties of the composites. The interlaminar shear strength increased from 11.5 MPa for the untreated jute fiber/polyester composite to 19.8 and 26.3 MPa for LF and RF oxygen plasma treated jute fiber/polyester composites, respectively. O₂ plasma treatment also improved the tensile and flexural strengths of jute fiber/ polyester composites for both plasma systems. It is clear that O₂ plasma treatment of jute fibers by using RF plasma system instead of using LF plasma system brings about greater improvement on the mechanical properties of jute/polyester composites.     

An improved shear lag model for predicting stress distribution in hybrid fiber reinforced rubber composites

An improved micromechanical shear lag model, which considers the interphase and bonded fiber end, is developed to investigate the load-carrying characteristics and stress profiles in hybrid aramid/sepiolite fiber reinforced rubber composites. The properties of the equivalent matrix, which is combination of sepiolite fiber and rubber matrix, are determined by Mori-Tanaka method. The axial and shear stresses at the fiber end are resolved by the imaginary fiber technique. The results obtained from the improved model show the tensile stress has a maximal at the real fiber center and the interfacial shear stress has a maximal at the end of the real fiber. Comparing with the results from Tsai’s model, the improved model has a better agreement with the numerical simualtion results. The effects of the imaginary fiber length on the stress transfer are analyzed and the results show that the effects can be ignored when the imaginary fiber length is greater than twice of the fiber radius. The effects of interphase modulus and thickness on the maximal axial and shear stresses are discussed. The results show that the interphase modulus and thickness of about 106.3 MPa and 0.2 μm are optimal to prevent interfacial debonding and improve the strength of hybrid fiber reinforced rubber composites.