Electron-beam-irradiated rice husk powder as reinforcing filler in natural rubber/high-density polyethylene (NR/HDPE) composites

The use of rice husk (RH) powder as a reinforcing filler in blends of natural rubber and high-density polyethylene (NR/HDPE) was studied via surface modification of the particle surface. The RH powder was pre-washed with sodium hydroxide (NaOH) prior to coating with liquid natural rubber (LNR) and reinforced by electron beam (EB) irradiation. The effects of the radiation dosage on the LNR-coated rice husk (RHr) as a reinforcing agent in the composite were evaluated from the mechanical and thermal properties, as well as from the blend homogeneity. The mechanical properties enhanced with the dosage of radiation on the RHr, and reached an optimum dose in the range 20–30 kGy. The composites filled with radiated RHr showed the highest storage modulus (E′) and low tangent delta (tan δ) a radiation dosage of 30 kGy. The scanning electron microscopy (SEM) micrograph of the fractural tensile surface showed that an effective RHr particle matrix interaction occurred in the RH powder at a radiation dosage of 20 kGy. Improved RH filler–matrix interfacial bond strength and adhesion to the matrix were achieved by coating the RH powder and curing the rubber coat by electron beam irradiation.     

The effects of a silane coupling agent on properties of rice husk-filled maleic acid anhydride compatibilized natural rubber/low-density polyethylene blend

Blends of natural rubber and low-density polyethylene were prepared in different weight compositions in presence of dicumyl peroxide and maleic acid anhydride. The effects of rice husk (RH) content and a silane coupling agent, that is, 3-aminopropyl triethoxy silane (3-APE, 1 wt% of filler content) on the physicomechanical properties and mass swell of the tested blend were investigated. The incorporation of untreated RH into the blend improved Young’s modulus, hardness but decreased tensile strength, elongation at break, impact strength, and mass swell. Incorporation of 3-APE has produced composite with improved tensile strength, Young’s modulus, hardness and impact strength with a sharp decrease in elongation, and better mass swell in comparison with untreated one. The effect of γ-irradiation doses on retained physicomechanical properties of RH (30 phr) filled blend samples before and after silane treatment was investigated at ambient temperature. The efficiency of silanized RH (30 phr) was also evaluated by the studies of the surface morphology (scanning electron microscopy) and thermal properties (thermal gravimetric analysis and thermal mechanical analysis).     

Gamma irradiation aging of NBR/CSM rubber nanocomposites

The effect of gamma-irradiation on the acrylonitrile butadiene/chlorosulphonated polyethylene rubber blends (NBR/CSM) based nanocomposites containing carbon black (CB) and silica filler (Si) were investigated by TG-DTG and ATR-FTIR techniques. The silica (with primary particle size of 22 nm) was added in content of 0, 10, 20 and 30 phr and carbon black (with primary particle size 40–48 nm) was added in content of 30 phr and rubber blend compounds were prepared. The obtained elastomeric materials were aging to different γ-irradiation doses (100, 200 and 400 kGy). The cure and mechanical properties of obtained nanocomposites were determined. Incorporating 20 phr of silica to the control NBR/CSM rubber blends containing 30 phr CB resulted 152% increase in tensile strength, 116%, in elongation at break and 142% modulus at 100% elongation, according to synergistic effect between the fillers. FTIR measurements of aged samples estimated the formation of alcohols, ethers and small amounts of lactones, anhydrides, esters and carboxylic acids after exposure to lower doses of γ-radiation (100 kGy). On the basis of the obtained spectra the formation of shorter polyene sequences and aromatic rings in aged elastomeric samples are assumed. The results show that 30 phr of carbon black (CB) and 20 phr of silica are needed for the best gamma aging resistance of NBR/CSM rubber nanocomposites. The result of radiation exposure is decrease in mechanical properties. The dose at which ultimate mechanical properties decreased was at 200 kGy. TG-DTG measurements estimated decrease in thermal stability of gamma-irradiated NBR/CSM rubber blend based nanocomposites. Silica reinforced NBR/CSM rubber blend had better radiation resistant than carbon black. Rough and heterogeneity of fracture surfaces has been observed for NBR/CSM rubber blends filled with silica. More uniform morphology of fracture surfaces according to high polymer–filler interaction and low filler–filler interaction has been observed for CB/Si filled NBR/CSM rubber blend.     

NR/CSM/biogenic silica rubber blend composites

Biogenic silica (BSi) was added at different ratios to some polymer blends of polyisoprene rubber (NR) and chlorosulphonated polyethylene rubber (CSM) cured by conventional sulfur system. The reinforcing performance of the filler was investigated using rheometric, mechanical and swelling measurements, differential scanning calorimetry (DSC), thermogravimetric (TGA) and scanning electron microscopy (SEM) analysis. There was a remarkable decrease in the optimum cure time (t_c90) and the scorch time (t_s2), which was associated with an increase in the cure rate index (CRI), with filler loading up to 30 phr in the different blend ratios. The tensile strength and hardness was 4–5 Sh-A higher in the case for the different blend compositions, while the resistance to swelling in toluene became higher. SEM photographs show that the filler is located at the interface between the different polymers which induces compatibilization in the immiscible blends. DSC scans of the filled blends showed shifts in the glass transition temperatures Tg which can be attributed to the improve interfacial bonding between filler and NR/CSM matrix. A higher thermal stability of NR/CSM/BSi composites was detected.     

Use of rice husks as potential filler in styrene butadiene rubber/linear low density polyethylene blends in the presence of maleic anhydride

In the present study, rice husks filled styrene butadiene rubber (SBR)/linear low density polyethylene (LLDPE) 50/50 blends with a compatibilizer, maleic anhydride (MAH) were prepared using a brabender plasti-corder. Virgin SBR/LLDPE blend was also prepared. The physico-mechanical as well as dielectric properties were investigated. Increasing MAH concentrations in SBR/LLDPE blends resulted in an increase in the tensile strength, elongation at break and hardness. After a certain concentration (2.5 phr), a reduction in these properties was found. On the other hand an increase in the dielectric properties as well as in the mass swell in both toluene and oil with MAH was noticed. After certain concentration of rice husk filler (25 phr) an abrupt increase in permittivity ε′ and dielectric loss ε″ was obtained. These results are supported by the mechanical properties measurements. The scanning electron microscopy (SEM) indicates that the presence of MAH increases the interfacial interaction between SBR/LLDPE blends on one hand and also rice husk filler and the blend on the other hand.     

Effects of electron beam irradiation on mechanical properties and nanostructural–morphology of montmorillonite added polyvinyl alcohol composite

This paper is aiming to analyze the effects of electron beam irradiation on the mechanical properties and structural–morphology of nano-sized montmorillonite (MMT) added polyvinyl alcohol (PVOH) composite. MMT particles were added to the PVOH matrix at various loading level that ranges from 0.5 to 4.5 phr MMT and electron beam irradiated with dosages ranging from 6 to 36 kGy. The results showed that tensile strength of MMT added PVOH composites at 1.5 and 2.5 phr MMT were observed marginally higher compare to neat PVOH when irradiation dosages increased to 26 kGy. However, when the concentration of MMT exceeded 2.5 phr, the application of irradiation seems to cause adverse effect to the PVOH–MMT composite. Besides, according to the X-ray diffraction analysis, the application of low irradiation dosage (⩽16 kGy) has significantly enhanced the intercalation effect of MMT particles at high loading (4.5 phr) in PVOH matrix. This also found to be consistent with the scanning electron microscopy observation where the dispersion of MMT particles in PVOH matrix was noted to be more homogeneous than non-irradiated samples. Further increment in irradiation dosage up to 36 kGy has significantly reduced the crystallinity which indicates the higher radiation energy could rupture the crystallite structures in PVOH matrix.     

Effect of γ-irradiation on the physical and mechanical properties of chitosan powder

In this study, locally produced chitosan powder was irradiated with pre-determined doses of γ-ray (Co-60) of 10 kGy, 25 kGy, 50 kGy and 100 kGy respectively. The properties of both chitosan powder and the chitosan film were examined and compared with unradiated chitosan. Physical characteristic of the irradiated powder and film was studied using stereo microscope. It was observed that the γ-ray induces a noticeable colour tone intensity change to the chitosan. Further investigation using Fourier Transformed Infrared Spectroscopy (FT-IR) analysis has confirmed that the chain scission reaction was occurred as a result of γ-ray exposure through the depolymerization mechanisms. Interestingly, the degree of deacetylation (DD) of chitosan measured using FT-IR showed a negligible effect due to the exposure of γ-ray radiation. Further investigation on the viscosity average molecular weight (M_v) showed a reduction of M_v from 577 kD of pure chitosan to 458 kD, 242 kD, 159 kD and 106 kD for 10 kGy, 25 kGy, 50 kGy and 100 kGy of γ-radiated chitosan respectively. In addition, the tensile strength and elongation at break showed a similar decreasing trend with increasing dosage of γ-ray.     

Chemical,morphological, and mechanical analysis of rice husk/post-consumer polyethylene composites

Composites were obtained from post-consumer high-density polyethylene (PE) reinforced with different concentrations of rice husk. PE and rice husk were chemically modified to improve their compatibility in composite preparation. Rice husk was mercerized with a NaOH solution and acetylated. The chemically modified fibers were characterized by FTIR and ¹³C NMR spectroscopy. The composites were prepared by extrusion of modified and unmodified materials containing either 5 or 10 wt.% fibers. The morphology of the obtained materials was analyzed by SEM. The chemical modification of the fiber surface was found to improve its adhesion with matrix. Flexural and impact tests demonstrated that PE/rice husk composites present improved mechanical performance comparatively to the pure polymer matrix, on the contrary no benefit is observed in the tensile strength over the pure PE.     

Dispersion and roles of montmorillonite on structural,flammability, thermal and mechanical behaviours of electron beam irradiated flame retarded nanocomposite

In this work, the effects of montmorillonite (MMT) dispersion and electron beam irradiation on intercalation and flammability-thermal behaviours of alumina trihydrate (ATH) added low density polyethylene and ethylene vinyl acetate (LDPE–EVA) blends were investigated. MMT and ATH added LDPE–EVA blends were compounded using Brabender mixer and compression moulded into sheets. The samples sheets were electron beam irradiated in the dosage range of 0 to 250 kGy. The dispersion and intercalation of nano-MMT in LDPE–EVA matrix were investigated through X-ray diffraction (XRD) analysis. The d-spacing measurements revealed that the addition of nano-MMT has effectively intercalated into polymer matrix and this has enhanced the compatibility of ATH particles and LDPE–EVA matrix. Limiting oxygen index test (LOI) revealed that the incorporation of MMT into ATH added LDPE–EVA blends as improved the flame retardancy up to 26.5 LOI%. Besides, the application of electron beam irradiation were also improved the flame retardancy of the blends by increasing the LOI% for about 2% compared to non-irradiated samples. The application of irradiation dosage up to 250 kGy has rapidly improved the thermal stability of blends by delaying decomposition temperature and also promoting formation of char. The increasing of MMT loading level and irradiation dosage has effectively enhanced tensile strength and Young’s modulus by intercalating polymer matrix into interlayer galleries of MMT particles. Beside, the formation of crosslinking networks in polymer matrix also could further enhance the tensile strength and Young’s modulus. The intercalation effect of MMT particles and formation of crosslinking networks in polymer matrix could improve the thermal and mechanical properties. Consequently, this study has demonstrated that addition of MMT and electron beam irradiation into ATH added LDPE–EVA blends could produce better flammability, thermal and physical properties of ATH added LDPE–EVA blends.     

稻壳粉/PP复合材料的力学性能

制备了稻壳粉/聚丙烯(PP)复合材料,分析了稻壳粉粒度及含量对PP复合材料力学性能的影响,用扫描电镜(SEM)对稻壳粉/PP复合材料拉伸断面进行了分析。结果表明,稻壳粉粒径和含量对PP复合材料性能有一定影响,稻壳粉粒径为245μm的PP复合材料有较好的综合力学性能;随着稻壳粉含量的增加,PP复合材料拉伸强度及断裂伸长率下降,稻壳粉含量为30%时,复合材料弯曲强度和模量均有最大值。稻壳粉含量较低时,其在PP中分散较好,与PP相容性好,复合材料为韧性破坏;稻壳粉含量较高时,稻壳粉有集聚现象,与PP相容性较差,材料的性能较低,复合材料为脆性破坏。     

Development of a new inexpensive green thermoplastic composite and evaluation of its physico-mechanical and wear properties

In the present study an attempt has been made to use turmeric spent (TS) as reinforcing filler to fabricate polypropylene (PP) green composite for load bearing and tribological applications. PP/TS composites were fabricated using varying amounts of TS viz, 10%, 20%, 30% and 40% (w/w) by twin screw extrusion method. The fabricated PP green composites were evaluated for physico-mechanical and tribological properties. Experimentally obtained tensile values were compared with theoretically predicted values using different theoretical models. Tensile modulus of composites increased from 1041 to 1771 MPa with the increase in filler addition from 0 to 40 wt.%. Flexural strength and flexural modulus of composites were improved after incorporation of TS into PP matrix. The water absorption characteristics of composites were determined. The effect of abrading distances viz., 150, 300, 450, and 600 m and different loads of 23.54 and 33.54 N at 200 rpm on the abrasive wear behaviour were studied using dry sand/rubber wheel abrasive test rig. The TS filler lowered the abrasion resistance of PP/TS composites. The wear volume loss and specific wear rate as a function of abrading distance and load were determined. The surface morphology of tensile fractured green composites and their worn surface features were examined under scanning electron microscope.     

矿物种类和粉体性质与增强性能的关系

测定了矿物的粒度、表面积、晶态及矿物填料/硅橡胶复合材料的力学性能,分析了矿物的种类和粉体的性质与增强性能的关系.在所选择矿物中,滑石、硅灰石、石英粉体具有较好的增强性能;粉体的粒度、表面积、形状是影响增强性能的重要因素,粉体的晶态不是主要的影响因素.     

Utilizing hydrolyzed powder recyclates as filler in polystyrene

In the present study, hydrolyzed powder coating wastes were used as filler materials in polystyrene compounds, and the effect on the mechanical properties, melt flow index and density of polystyrene compounds were investigated. Epoxy/polyester, epoxy and polyurethane systems with thermoset structure were used as powder coating recyclates. After separately hydrolyzing these wastes, 5 %, 10 %, 20 % and 30 % by weight were homogeneously mixed with polystyrene, initially mechanically and subsequently with an extruder in the melt at 180 °C. The resulting compounds were cooled and granulated, and by use of an injection molding machine at 180 °C to 200 °C, standard tensile test bars were produced. Tensile strength, bending strength and izod impact strength of the test bars were measured and the variations of the mechanical properties of the polystyrene compounds as a function of the type and amount of filler were examined. In addition, melt flow index and density of the compounds were determined. Furthermore, the bonding mechanism of filler and matrix material was examined by electron microscopy.     

Thermo-mechanical properties enhancement of bio-polyamides (PA10.10 and PA6.10) by using rice husk ash and nanoclay

Composites consisting of fully (PA10.10) and partially (PA6.10) bio-based polyamides and 10–20 wt.% rice husk ash (RHA) was prepared by melt compounding. The mechanical analysis data showed that RHA induced significant improvement in Young’s modulus, a slight reduction in the tensile strength and a large decrease in the deformation at break. Pukanszky’s model was used to evaluate the filler–matrix interactions. The two PAs exhibited similar filler–matrix load transfer with RHA and better performance than polylactic acid (PLA). The addition of modified clay (Cloisite 30B) to the systems with 10 wt.% of RHA gave the best mechanical properties and filler–matrix interactions, notwithstanding the matrix used. Finally, DMT analyses demonstrated that the addition of RHA caused an increase in the heat deflection temperature (HDT) compared to the neat PA matrices. Furthermore, the simultaneous presence of RHA and clay provided the best results.     

稻壳源白炭黑/炭黑并用对天然橡胶协同补强作用研究

通过扫描电镜观察了稻壳源白炭黑(RHS)在天然橡胶(NR)交联体系中的分散,显示RHS作为刚性补强粒子微观呈纳米尺度均匀分布,这是补强作用的基础。依据非平衡态分子动力学原理,探究了RHS纳米粒子与炭黑(CB)对NR的协同补强作用机理。通过研究双相填料(RHS/CB)对NR协同补强作用,不同的RHS/CB比例对协同补强作用影响较大,适宜的用量比不仅提高物理力学性能,同时改善动态力学性能。     

稻壳灰/天然橡胶胶乳复合材料结构与性能研究

采用稀土偶联剂和硅烷偶联剂改性稻壳灰(RHA)填充天然胶乳(NRL)制备稻壳灰/天然橡胶胶乳复合材料,用扫描电镜(SEM)、热重分析仪(TG-DTG)以及力学性能测试等技术研究了稻壳灰在复合材料中的结构、形态分布和热氧稳定性及力学性能。结果表明,采用偶联剂对RHA进行改性处理,能显著改善RHA在橡胶相的分散程度,增强RHA粒子与橡胶基体之间作用力,从而提高RHA/NRL复合材料的力学性能和抗氧老化性能,并且稀土偶联剂RHA/NR复合材料力学性能和抗氧老化性能的改进更加明显。     

电子束辐射交联硅橡胶的力学性能及导热性能

采用导热无机填料氧化铝对甲基乙烯基硅橡胶进行改性,并采用电子束辐射交联硅橡胶,对辐射交联硅橡胶的力学性能及导热性能进行了研究。结果表明,随着辐射剂量的增加,硅橡胶的交联密度增大,拉伸断裂强度逐渐增加,当辐射剂量为30kGy时,强度出现极大值;断裂伸长率则随着辐射剂量的增加而逐渐下降。随着白炭黑含量的增加,硅橡胶的拉伸断裂强度及断裂伸长率均逐渐增加。导热无机填料氧化铝的加入能够有效地提高硅橡胶的导热率。随着氧化铝含量的增加,硅橡胶的导热系数逐渐增大,共混体系的拉伸断裂强度和断裂伸长率下降,硬度增加。     

Influence of untreated and novel electron beam modified surface coated silica filler on rheometric and mechanical properties of ethylene-octene copolymer

Surface modified silica fillers have been developed by coating these with a silane coupling agent, triethoxyvinyl silane (TEVS) followed by electron beam irradiation at room temperature. These have been incorporated in an ethylene-octene copolymer rubber. Rheometric, mechanical, volume swelling and aging properties of the gum as well as the filled elastomers have been studied in details. A significant improvement in the above properties has been noticed for these vulcanizates, which clearly emphasizes that novel surface modified silica improves polymer-filler adhesion by the introduction of covalent bonds between the filler surface and the rubber chains. Filler-filler and polymer-filler interactions have been quantified with the help of a mathematical model correlating the modulus and the volume concentration of filler. The influence of electron beam treatment on silanized silica filler has also been demonstrated from the above model.     

Electrorheological properties of novel piezoelectric lead zirconate titanate Pb(Zr0.5,Ti0.5)O3-acrylic rubber composites

Perovskite lead zirconate titanate, comprised of PbTi_1 ? xO₃ and PbZr_xO₃, was synthesized at a temperature below the Curie temperature, T_C. The tetragonal form obtained is a noncentrosymmetric structure capable of spontaneous polarization. FTIR spectra and XRD patterns confirm the successful synthesis of the lead zirconate titanate (PZT). PZT particles were mixed with an arcrylic rubber solution and cast as a thin sheet. SEM micrographs indicate that PZT particles are moderately dispersed in the acrylic rubber (AR71) matrix. Without electric field, the particles merely act as a reinforcing filler which can absorb and store additional stress. Under electric field, particle-induced dipole moments are generated, leading to interparticle interactions, and a substantial increase in the storage modulus. At a lead zirconate titanate volume fraction of 0.038600, the storage modulus response attains its maximum value with the corresponding storage modulus sensitivity value of 0.58 as the electric field strength is varied from 0 to 2 kV/mm.     

石墨烯/环氧树脂复合涂层的γ射线辐照损伤及其腐蚀防护性能

用硅烷偶联剂对石墨烯表面进行修饰, 制备石墨烯/环氧树脂复合涂层。通过交流阻抗(EIS)和塔菲尔极化曲线(Tafel slope)等电化学方法分析复合涂层经伽马射线辐照后的腐蚀防护性能。采用电子自旋共振(ESR)和傅里叶红外光谱分析仪(FTIR)等测试复合涂层的γ射线辐照损伤, 探索了石墨烯在环氧树脂中抗辐照损伤的作用机理。Tafel结果显示复合涂层经280 kGy辐照后, 腐蚀电流为6.140×10^-9 A/cm², 而纯环氧树脂涂层的腐蚀电流则为1.340×10^-8 A/cm², 说明石墨烯可以使复合涂层保持较好的腐蚀防护性能。ESR分析表明, 复合涂层中的石墨烯可以降低环氧树脂基体在γ射线辐照过程中产生的过氧自由基, 表明石墨烯可有效吸收辐照过程中的自由基。辐照前后复合涂层的FT-IR图谱没有发生明显变化, 说明石墨烯有效降低了伽马射线对环氧树脂的结构损伤。因此, 可以认为石墨烯能够减缓环氧树脂在高能辐照环境中的老化, 从而延长其使用寿命。