Epoxidised soybean oil polymer composites reinforced with modified microcrystalline cellulose

Microcrystalline cellulose (MCC) grafted with n-octadecyl isocyanate (18C-g-MCC) was introduced as the reinforcing filler in epoxidised soybean oil (ESO) polymer. The wetting characteristics of 18C-g-MCC were evaluated by static contact angle and the results show that the hydrophobicity of MCC was improved by the introduction of nonpolar alkyl groups. The ESO composites were synthesised with different contents of 18C-g-MCC (from 0 to 25 wt%) by a thermally cured method. The reinforcing effects of 18C-g-MCC were evaluated by scanning electron microscopy, mechanical test, dynamic mechanical analysis and thermal stability test. The results show that the tensile strength, the impact strength, Young's modulus, the flexural strength and glass transition temperature of the composites increase gradually with the increase of 18C-g-MCC content, while the elongation at break begins to decrease with 18C-g-MCC content of more than 20 wt%. Contact angle and water absorption analysis of the composites indicate the addition of 18C-g-MCC increases the water absorption of the ESO polymer.     

Water absorbent polyurethane composites derived from molasses and lignin filled with microcrystalline cellulose

Water absorbent polyurethane (PU) rigid composite foam was prepared using polyols derived from molasses and lignin filled with microcrystalline cellulose (MCC) powder with various particle sizes. By combining biomaterial components, preparation conditions were examined in order to obtain PU foams showing reliable water-adsorbing properties. Water absorbing capabilities, such as, water absorbing time, water retention in air as a function of time, and also mechanical properties in dry and wet state, were investigated. Rigid PU composite foams having equilibrium water retention ca. 1.0 g cm⁻³, maintain ca. 0.7 g cm⁻³ retention water in air after 24 h. Compression strength in the wet state was ca. 50 kPa and compression modulus ca. 1 MPa. MCC acts as a quick water absorbent in the initial stage of water immersion and PU matrix restrains a large amount of water for a long period.     

Performance properties of microcrystalline cellulose as a reinforcing agent in wood plastic composites

Polypropylene (PP)/microcrystalline cellulose (MCC)/wood flour composites were prepared containing polypropylene-graft-maleic anhydride (PP-g-MA) as compatibilizer. The mechanical, morphological and thermal properties were investigated. The weight ratio of the cellulosic materials to polymer matrix was 40:60 (w:w). The obtained results showed that tensile, flexural and impact strengths of the composites were significantly enhanced with addition of MCC, as compared with pure PP and composites without MCC. The effect of MCC on impact was minimal compared to the effects of PP-g-MA content. Scanning electron microscopy has shown that the composite, with compatibilizer, promotes better fiber–matrix interaction. In all cases, the degradation temperatures shifted to higher values after addition of PP-g-MA. The maximum improvement on the thermal stability of the composites was achieved when 5% PP-g-MA was used. However, the increase in MCC content substantially reduced the thermal stability. This work showed that MCC along with wood flour could be effectively used as reinforcing agent in thermoplastic matrix.     

微晶纤维素/聚丁二酸丁二醇酯复合材料的流变行为

采用熔融共混法制备了微晶纤维素/聚丁二酸丁二醇酯(MCC/PBS)复合材料,用高级毛细管流变仪和旋转流变仪分别测定复合材料的稳态流变性能和动态流变性能,研究了不同MCC含量、不同温度对复合材料流变行为的影响。结果表明,复合材料的黏度与剪切速率的流变曲线符合幂律流体的特征,可以用幂律模型对其进行拟合;复合材料的黏度与温度的关系可用Arrhenius方程对其进行描述。在线性黏弹区,复合材料的储能模量(G′)维持恒定,当应变(γ)超过临界值(γ_c)时,复合材料进入非线性黏弹区,出现了"Payne"效应,并且随着MCC含量的增加,γ_c下降。在角频率(ω)扫描范围内,复合材料的储能模量(G′)、损耗模量(G″)和复数黏度|η*|均随着MCC含量的增加而增大。在相同的MCC含量下,G″的值始终大于G′的值,损耗因子(tanδ)均大于1。在低频区,G′出现第二平台。MCC/PBS复合材料加工流变特性的研究,对指导MCC/PBS复合材料的成型加工具有一定的价值。     

Weight and weight uniformity of hard gelatin capsules filled with microcrystalline cellulose and silicified microcrystalline cellulose

The objective of this study was to investigate the weight and weight uniformity of hard gelatin capsules filled with microcrystalline cellulose (MCC) and silicified microcrystalline cellulose (SMCC) powdered formulations. A tamping-type encapsulation apparatus was used to fill the capsules. The four formulations that were tested included MCC alone, MCC blended with fumed silica, SMCC, and high-density SMCC (SMCC-HD). The mean capsule weight and the average variation in mean capsule weight of each formulation were determined. Both SMCC products exhibited better flow than the MCC alone, with SMCC-HD being the freest flowing of the powders investigated. Capsules filled with the SMCC products had higher fill weights than those containing the MCC powders. The SMCC-containing capsules exhibited the lowest variation in weight, although these findings were not significantly different from either of the MCC-containing capsules. Significantly higher weight variations were found in capsules filled with SMCC-HD. A relationship between Carr's compressibility index and capsule weight variation was found, with more compressible materials producing more uniformly filled capsules. No relationship could be established between powder flow and capsule weight uniformity. These findings suggest that powder flow may not be a critical parameter in ensuring capsule weight uniformity when the encapsulation equipment utilizes a tamping-type filling system.     

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.     

Functional performance of silicified microcrystalline cellulose versus microcrystalline cellulose: a case study

Background: During the development of a tablet dosage form of an investigational compound, R411, several aspects were identified as critical quality attributes that required optimization. The use of nonsolvent processing prevented the moisture-induced physical changes in the drug product but presented manufacturing challenges related to sticking during compression and slowdown in dissolution after storage at stress conditions. Aim: The aim of this study was to evaluate silicified microcrystalline cellulose (SMCC), microcrystalline cellulose (MCC), and physical mixture of MCC–colloidal silicon dioxide (MCC/CSD at 98:2 ratio) as extragranular compression aids to address the processing and dissolution stability issues of this formulation. Methods: The compactibility and stickiness upon compression over extended period of time as well as the dissolution of R411 formulations incorporating the aforementioned compression aids were investigated. In addition, the water sorption/desorption properties of these compression aids were determined. Results: All formulations showed comparable compactibility irrespective of the compression aid used. Nevertheless, MCC alone or in a physical mixture with CSD showed sticking of the lower punches, whereas SMCC resulted in clean punch surface during extended compression runs. Furthermore, the three compression aids were compared for their effect on dissolution stability after storage at stress conditions. The formulations containing SMCC provided superior dissolution stability over the other compression aids evaluated in the study. Conclusions: Novel functionalities of SMCC are presented in terms of sticking prevention while having the most beneficial effect on dissolution stability in R411 formulation.     

Thermo-mechanical properties of innovative microcrystalline cellulose filled composites for art protection and restoration

Microcrystalline cellulose (MCC) powder was selected as a natural reinforcement for a commercial acrylic adhesive widely used in the field of art protection and restoration (Paraloid B72). In particular, various amounts (from 5 to 30 wt%) of MCC were melt compounded with Paraloid B72 to prepare new thermoplastic polymer composites for the cultural heritage conservation field. Scanning electron microscopy showed that MCC flakes are uniformly dispersed within the matrix at all the tested compositions, without preferential orientation. Thermogravimetric analysis evidenced an increase of thermal stability due to the MCC introduction, even at low filler amounts, while DSC measurements demonstrated that the glass transition temperature progressively increases with the MCC content. Interestingly, DMTA analysis revealed a stabilizing effect on the material produced by microcellulose addition, with an increase of the storage modulus and a decrease of the thermal expansion coefficient, in proportion to the filler loading. Moreover, MCC addition determined an increase of the elastic modulus and creep stability with respect to the neat resin, and an enhancement of fracture toughness (K _IC).     

Adsorption of an amine drug onto microcrystalline cellulose and silicified microcrystalline cellulose samples

The adsorption of a model amine drug (tacrine hydrochloride) from aqueous solution onto 21 microcrystalline cellulose (MCC) based samples has been investigated. The MCC source (manufacturer) affected adsorption. The adsorption appeared to be fully reversible. Adsorption was reduced by the use of high-density grade MCC, high-energy milling, and silicification. Adsorption of the model drug was not affected by the particle size of the MCC. Significant variations of the adsorption characteristics between batches of certain MCC products were found. The primary mode of adsorption was by ion exchange.     

微晶纤维素的制备及性质研究

分别用HCl和H2SO4处理从棉纤维和稻秆中提取的纤维素，制备得到微晶纤维素。研究了酸处理对微晶纤维素的聚合度、结晶度、体积密度和热稳定性的影响．X射线衍射结果表明，纤维素微晶化后仍保持原来的晶型和晶区和非晶区两相共存的微细结构。扫描电子显微镜测试结果表明，不同原料，酸处理后所得产物的形态不同．     

白炭黑的功能化改性及其改性橡胶基复合材料的制备与表征

利用沉淀法白炭黑生产工艺,在相同的条件下,选用不同质量分数的羟基羧酸酯作为改性剂进行湿法改性,研究了白炭黑/天然橡胶(NR)复合橡胶的力学性能、动态性能以及动态生热性能。结果表明:制备的白炭黑均为非晶态白炭黑,采用质量分数为6%的羟基羧酸酯改性的白炭黑,其分散性好,颗粒分布均匀,呈近球状,经羟基羧酸酯改性后的白炭黑有效的去除了部分亲水基团,改善了其在NR中的分散性。随着白炭黑用量的增加,分散性变差,损耗因子和动态温升均有所提高,Payne效应增大。当白炭黑用量达到临界值(白炭黑与NR质量比为40∶100)时,白炭黑/NR复合材料表现出较好的性能,改性白炭黑/NR复合材料比未改性白炭黑/NR复合材料的硬度、拉伸强度、断裂伸长率有所提高,而磨耗体积和动态生热则有所下降。动态力学性能测试结果表明,改性白炭黑与天然橡胶的质量比为40∶100时,改性白炭黑/NR复合材料的60℃滚动阻力损耗因子由0.123降到0.104。SEM结果表明,改性白炭黑在橡胶基体中的分散性优于未改性白炭黑,与NR基体界面结合的更加紧密。     

The toughness of epoxy polymers and fibre composites modified with rubber microparticles and silica nanoparticles

The present paper investigates the effect of adding silica nanoparticles to an anhydride-cured epoxy polymer in bulk and when used as the matrix of carbon- and glass-fibre reinforced composites. The formation of ‘hybrid’ epoxy polymers, containing both silica nanoparticles and carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber microparticles, is also discussed. The structure/property relationships are considered, with an emphasis on the toughness and the toughening mechanisms. The fracture energy of the bulk epoxy polymer was increased from 77 to 212 J/m² by the presence of 20 wt% of silica nanoparticles. The observed toughening mechanisms that were operative were (a) plastic shear-yield bands, and (b) debonding of the matrix from the silica nanoparticles, followed by plastic void-growth of the epoxy. The largest increases in toughness observed were for the ‘hybrid’ materials. Here a maximum fracture energy of 965 J/m² was measured for a ‘hybrid’ epoxy polymer containing 9 wt% and 15 wt% of the rubber microparticles and silica nanoparticles, respectively. Most noteworthy was the observation that these increases in the toughness of the bulk polymers were found to be transferred to the fibre composites. Indeed, the interlaminar fracture energies for the fibre-composite materials were increased even further by a fibre-bridging toughening mechanism. The present work also extends an existing model to predict the toughening effect of the nanoparticles in a thermoset polymer. There was excellent agreement between the predictions and the experimental data for the epoxy containing the silica nanoparticles, and for epoxy polymers containing micrometre-sized glass particles. The latter, relatively large, glass particles were investigated to establish whether a ‘nano-effect’, with respect to increasing the toughness of the epoxy bulk polymers, did indeed exist.     

Effect of the temperature on surface modification of silica and properties of modified silica filled rubber composites

The modified silica at different temperature (MSaDT) with bis(3-triethoxysilylpropyl)tetrasulfide (TESPT), and MSaDT filled solution styrene butadiene rubber (SSBR) composites were prepared to investigate the effect of temperature on surface modification of silica. The results showed that TESPT was successfully bonded on the surface of silica by chemical bonds. The grafting degree (K) of MSaDT of 50 °C was 62.2% and higher than that at the other temperatures. The thermal weight loss and the size distribution of MSaDT showed that the silanol of TESPT hydrolysates reacted with the surface hydroxyl groups of silica, decreasing the average size and agglomeration of modified silica. For 50 °C modified silica/SSBR composite, the static mechanical properties and rubber–filler interaction of the composite were better than those of the others. As far as dynamic mechanical properties are concerned, the 50 °C modified silica/SSBR composite owned a best combination of low rolling resistance and high wet skid resistance.     

Organosulfonic acid-functionalized mesoporous composites based on natural rubber and hexagonal mesoporous silica

This study is the first report on synthesis, characterization and catalytic application of propylsulfonic acid-functionalized mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). In comparison with propylsulfonic acid-functionalized HMS (HMS-SO₃H), a series of NR/HMS-SO₃H composites were prepared via an in situ sol–gel process using tetrahydrofuran as the synthesis media. Tetraethylorthosilicate as the silica source, was simultaneously condensed with 3-mercaptopropyltrimethoxysilane in a solution of NR followed by oxidation with hydrogen peroxide to achieve the mesoporous composites containing propylsulfonic acid groups. Fourier-transform infrared spectroscopy and ²⁹Si MAS nuclear magnetic resonance spectroscopy results verified that the silica surfaces of the NR/HMS-SO₃H composites were functionalized with propylsulfonic acid groups and covered with NR molecules. After the incorporation of NR and organo-functional group into HMS, the hexagonal mesostructure remained intact concomitantly with an increased framework wall thickness and unit cell size, as evidenced by the X-ray powder diffraction analysis. Scanning electron microscopy analysis indicated a high interparticle porosity of NR/HMS-SO₃H composites. The textural properties of NR/HMS-SO₃H were affected by the amount of MPTMS loading to a smaller extent than that of HMS-SO₃H. NR/HMS-SO₃H exhibited higher hydrophobicity than HMS-SO₃H, as revealed by H₂O adsorption–desorption measurements. Moreover, the NR/HMS-SO₃H catalysts possessed a superior specific activity to HMS-SO₃H in the esterification of lauric acid with ethanol, resulting in a higher conversion level.     

纳米微晶纤维素对白炭黑／天然橡胶复合材料性能的影响

采用硫酸酸解微晶纤维素（MCC）的方法制备了纳米微晶纤维素（NCC）,并将其作为填料部分替代白炭黑（SiOz）,制备了纳米微晶纤维素一白炭黑／天然橡胶（（NCC—SiO。）／NR）复合材料。结果表明,NCC的加入在保持SiO2增强NR基本力学性能的同时,使压缩永久变形由11．4％下降到5．9％,压缩疲劳生热则由19．9...     

Extrudate fracture and spheronisation of microcrystalline cellulose pastes

An experimental study of the ram extrusion and subsequent spheronisation of water-based microcrystalline cellulose (MCC) pastes has been performed. The effects of extrusion velocity, die geometry, and paste water content on the integrity of the extrudate produced were investigated. The apparent severity of extrudate fracture increased with decreasing die length/diameter ratio (L/D), and increasing extrusion velocity. The spacing between the fractures was approximately constant for a given set of process conditions, and increased with increasing émph{L/D} and decreasing extrusion velocity, whilst the flare of the extrudate fracture segment increased with decreasing émph{L/D} and increasing extrusion velocity. Two types of fracture shape were identified, émph{viz}. knuckle-bones and cups, the occurrence of which is explained in terms of the relative extent of the radial and axial strain release at the surface of the extrudate upon exiting the die.The shape and size distributions of the corresponding spheronised pellets were analysed and related to the geometry of the extrudate fracture segments. Severe knuckle-bone fracture gave spherical pellets with a wide size distribution. Visibly smooth extrudates gave non-spherical pellets with an apparently narrow size distribution (as measured by sieving). Extrudates displaying the cup type of fracture generated the best quality pellets in terms of both sphericity and size distribution.     

Low-temperature particle synthesis of titania/silica/natural rubber composites for antibacterial properties

Composite particles of titania/silica/natural rubber (TiO₂/SiO₂/NR) were prepared and evaluated for their potential antibacterial application. All processes were restricted to a low temperature or a small heating contact time to avoid degradation of the NR. The primary NR particles were synthesized by spray drying and then SiO₂ and TiO₂ were incorporated sequentially by chemical vapor deposition and liquid phase deposition, respectively. The physical and chemical properties were characterized by X-ray diffractometry, scanning electron microscopy with energy dispersive X-ray spectrometry, Fourier-infrared spectroscopy and thermogravimetric analyses. The TiO₂/SiO₂/NR composite particles had a spherical shape with a diameter of about 10 μm, with titania on the outer layer, and showed an effective antibacterial activity of a 99.99% reduction in viable Escherichia. coli and Staphylococcus aureus within 20 min of exposure under fluorescent light. In addition, the particles could be reused with the same level of antibacterial activity for up to three cycles. The structural and antibacterial models of the composite particles are proposed in this work.