Thermal,Mechanical and Morphological Characterization of Jute/Gelatin Composites

Jute fabrics/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 20–60 wt%. Composites were subjected to mechanical, thermal, water uptake and scanning electron microscopic (SEM) analysis. Composite contained 50 wt% jute showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength of the 50% jute content composites were found to be 85 MPa, 1.25 GPa, 140 MPa and 9 GPa and 9.5 kJ/m², respectively. Water uptake properties at room temperature were evaluated and found that the composites had lower water uptake compared to virgin matrix.     

The Preparation and Characterization of Silk/Gelatin Biocomposites

There is a growing interest in the use of composite materials. Silk fiber/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 10–30 wt%. Composite containing 30 wt% silk showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength, hardness of the 30% silk content composites were found 54 MPa, 0.95 GPa, 75 MPa and 0.43 GPa and 5.4 kJ/m², 95.5 Shore A, respectively. Water uptake properties at room temperature, accelerated weathering aging, irradiation, thermomechanical analysis, and degradation in soil were carried out in this experiment.     

MCC对PLA/PPC复合材料力学性能与热稳定性的影响

以微晶纤维素(MCC)作为改性剂,马来酸酐接枝聚乳酸(PLA g MAH)为界面相容剂,聚乳酸(PLA)、聚碳酸亚丙酯(PPC)为基体,通过熔融共混法制得PLA/PPC/MCC三元复合材料。采用控温拉伸、动态热分析、扫描电子显微镜以及热失重分析等方法研究了MCC对PLA/PPC的力学性能和热稳定性。结果表明,PLA/PPC/MCC三元复合材料的拉伸强度提高了12.7 %,玻璃化转变温度（Tg）提高了9.8 ℃;PLA g MAH的加入可以改善PLA/PPC/MCC三元复合材料的界面性质,从而提高力学性能和热稳定性;当PLA g MAH的添加量为5 %（质量分数,下同）时,三元复合材料在常温下的拉伸强度、弯曲强度和冲击强度分别提高了53.7 %、43.1 %和18.5 %;在60 ℃下三元复合材料的断裂强度提高了80 %;热降解温度以及最大失重温度与PLA/PPC相比分别提高了25.31 ℃和61.83 ℃。     

A Study on Structure and Mechanical Properties of Polyurethane/Organic-Montmorillonite Nanocomposites

The intercalated nanocomposites of polyurethane (PU) with organic-montmorillonite (OMMT) treated by cetryltrimethyl ammonium bromide was prepared. The interlayer spacing of PU/OMMT nanocomposites was 3–4 nm. The interface interaction of PU/OMMT nanocomposites was improved compared to that of PU/montmorillonite (MMT) composites. The orderly arrangement of the PU chains was hindered because of strong interface interaction between the silicate layers dispersed in the nanometer and PU chains. By adding 2 wt% OMMT to PU, tensile strength and tear strength of the PU/OMMT composites were increased from 10.5 MPa and 36.4 KN/m to 13.8 MPa and 42.2 KN/m, respectively. The tensile strength and tear strength increased with OMMT content firstly, reaching its maximum when the OMMT content was 8 wt%. After that, the tensile strength and tear strength decreased with the further increase of the OMMT content. Compared to that of PU, the elongation at break of the PU/OMMT nanocomposites increased, indicating that the stretch of PU/OMMT nanocomposites increased.     

Pultruded fiber-reinforced polyurethane-toughened phenolic resin. II. Mechanical properties,thermal properties,and flame resistance

A novel process has been developed to toughen phenolic resin by polyurethane for fiber-reinforced pultruded composites. The mechanical properties of the composites (tensile strength, flexural strength, and notched Izod impact strength) approach maximum values at 10 wt% of the blocked polyurethane content. The fabricated composites show good mechanical properties and possess low void fraction. Notched Izod impact strength of the composite (with 5 wt% polyurethane content) increases by more than 30% compared to the virgin composite. The thermogravimetric analysis (TGA) showed that the temperature for the 5% weight loss of the phenolic/polyurethane copolymer decreases with the increasing of the polyurethane content; however, the thermal degradation temperature is still higher than 350°C. Differential scanning calorimetric analysis (DSC) showed that the onset point of copolymer is 20°C higher than that of the virgin one. The presence of the blocked polyurethane may hinder the polymerization of phenolic resin. The modified composite shows excellent dimensional stability. The copolymer composite also possesses good fire resistance. © 1996 John Wiley & Sons, Inc.     

Plasticizing while toughening and reinforcing poly(propylene carbonate) using low molecular weight urethane: Role of hydrogen-bonding interaction

Poly(propylene carbonate) (PPC), a biodegradable plastic produced by alternating copolymerization of carbon dioxide and propylene oxide, is amorphous at glass-transition temperature of ∼35 °C; therefore, it becomes brittle at temperatures <20 °C. This article reports on the synthesis of low molecular weight urethanes, such as 1,6-bis(hydroxyethyl urethane)hexane (BEU), 1,6-bis(hydroxyisopropyl urethane)hexane (BPU), and 1,6-bis(methyl urethane)hexane (HDU) bearing rich NH and CO bonds, by a non-isocyannate method and their use as plasticizers for PPC. The hydrogen-bonding interaction between BPU and PPC was found to be significantly more effective as compared with BEU and HDU, and the highest hydrogen-bonding interaction fraction reached 5.2% in a PPC/BPU blend with 15 wt% BPU loading. Solubility parameters calculated from Hoy’s method, in combination with differential scanning calorimetric analysis, indicated that HDU and BPU were miscible with PPC at a molecular scale, while BEU was immiscible with PPC. Usually, plasticizing is generally accompanied by sacrificing of tensile strength; however, it was encouraging to observe that the elongation at break for PPC/HDU blend with 10 wt% of HDU loading reached 727% - an increase 53 times that of pure PPC - while the tensile strength was maintained at 30 MPa, which was comparable with that of linear low-density polyethylene. The hydrogen-bonding interaction generated a remarkable improvement in the mechanical performance of PPC; it not only confined the migration of the plasticizer to the surface and thus ensured stability of the blending material over time, but it also maintained the mechanical strength of the plasticized PPC.     

Mechanical,morphological, thermal properties and hydrolytic degradation behavior of polylactic acid/polypropylene carbonate blends prepared by solvent casting

The preparation of polylactic acid (PLA) and polypropylene carbonate (PPC) blend films by using the solvent casting method is to improve the properties of pure PLA. The blends' mechanical and thermal properties, morphological as well as hydrolytic degradation behavior are evaluated. The tensile test proved that the increase of PPC from 0 wt% to 75 wt% could improve the elongation of pure PLA when the graph showed a significant increase of the elongation from 10% to 1000%. Scanning Electron Microscopy (SEM) supported the significant increase in elongation of the blends when it shows a definite phase separation in 75/25 PLA/PPC, where 25% of PPC has formed islands in the PLA matrix. Differential scanning calorimetry indicates the partial miscibility of the blends where two peaks of the glass transition temperature moved towards each other when the amount of PPC increases. Fourier transform infrared (FTIR) spectroscopy revealed a possible intermolecular interaction between two polymers, which affects the miscibility of the blends. Finally, the hydrolytic degradation test indicates that the degradation started from the PLA phase and the blends' degradation rate decrease as wt% of PPC increase.     

Studies on Preparation and Property Researches of EP/SiC Thermal Conductivity Composites

The epoxy resin/silicon carbide thermal conductivity composites were prepared via casting method. The content of SiC and coupling reagents effecting on the thermal conductivity, mechanical and thermal properties of composites were investigated. Results revealed that the thermal conductivity properties of the composites were improved with the increasing mass fraction of SiC, and the thermal conductivity coefficient λ was 0.7152 W/mk with 50% mass fraction of SiC, being over 3 times of that of native epoxy resin. The flexural strength and impact strength of the EP/SiC composites increased firstly, but decreased with excessive addition of SiC, and the properties of EP/SiC composites were maximum with 10 wt% SiC. DSC and TGA analysis showed that the glass transition temperature (Tg) of composites decreased, but the heat resistance increased with the addition of SiC. SEM observation of impact fracture revealed that the impact strength had the relationships of large or small fracturing ability and the fracturing extended ability and the resin elasticity deformation.     

Polymethylmethacrylate grafting onto polyvinyl alcohol/modified feldspar composites: preparation,properties and structure characterization

The orthogonal experiment design methods were used to select the optimal conditions of preparation for modified feldspar via conventional wet method with silane coupling agent KH570. The optimum scheme was followed by: reaction time 1.5 h, modifier content 8 wt%, pulp density 12 wt%, reaction temperature 70 °C, respectively. Furthermore, polyvinyl alcohol (PVA)/modified feldspar composites were prepared with feldspar coated with silane coupling agent KH570 via solution method. To improve the water resistance of PVA-based composites, polymethylmethacrylate grafted onto PVA/modified feldspar composites (PMMA-g-PVA) was obtained by surface-initiated atom transfer radical polymerization (SI-ATRP). PVA/modified feldspar composites before and after SI-ATRP were characterized by X-ray photoelectron spectroscopy, thermal gravimetric analyzer, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy, successively. The tensile performance and water resistance of PVA/modified feldspar composites were tested by mechanical test and contact angle, respectively. It was shown that 5 wt% of modified feldspar could significantly improve the tensile strength of PVA-based composites. Moreover, both thermal stability and hydrophobicity for PVA/modified feldspar composites were distinctly enhanced after SI-ATRP. In all, this study provided an effective and feasible method for optimizing interface performance and enhancing the water resistance of PVA-based composites.     

The excellent gas barrier properties and unique mechanical properties of poly(propylene carbonate)/organo-montmorillonite nanocomposites

Intercalated nanocomposites comprised of poly(propylene carbonate) (PPC) and organo-montmorillonite (OMMT) were prepared via a direct melt blending method. The morphological, thermal, rheological, mechanical, and gas barrier properties of composites were carried out in detail. Results of XRD, TEM, and SEM revealed that OMMT dispersed homogeneously in the polymer matrix, and were intercalated by PPC macromolecules. Compared with neat PPC, the PPC/OMMT nanocomposites showed an enhancement in the 5 wt% weight loss temperature (T _?5%) by near 20 °C with 3 phr OMMT concentration. With the percolation threshold formed, the rheological properties of composites translated from a liquid-like behavior to a solid-like one. Interestingly, PPC/OMMT nanocomposites revealed a concurrent improvement in the modulus, yield strength, and toughness with the addition of homogeneously dispersed clay. The oxygen permeability of well-dispersed PPC/OMMT nanocomposites reduced significantly compared with that of neat PPC. Consequently, this convenient and effective method, which facilitates to prepare PPC/OMMT nanocomposites with superior mechanical properties and excellent gas barrier performances, can be considered to broaden the application of PPC.     

Enhanced thermal and mechanical properties of epoxy composites by addition of hyperbranched polyglycerol grown on cellulose fibers

We reported a novel approach for epoxy composites by incorporation of hyperbranched polyglycerol (HPG) grafted sisal cellulose fibers (SCF). In this work, we have synthesized SCF wrapped HPG shell (SCF-g-HPG) by a “grafting from” strategy for the strong interfacial interaction between fillers and matrix. It was found that the thermal and mechanical properties of epoxy composites were greatly improved by incorporating SCF-g-HPG. For example, the impact strength, flexural strength, tensile strength, Young’s modulus and toughness of the composites with 3.0 wt% SCF-g-HPG loading were 38.35 KJ/m², 123.40 MPa, 86.62 MPa, 151.7 MPa, and 417.84 MJ/m³, significantly increased by 119.1 %, 55.2 %, 45.6 %, 43.1 %, and 166.1 % respectively, as compared with neat epoxy. In addition, thermal stability of SCF-g-HPG/epoxy composites also showed an obvious enhancement compared with neat epoxy.     

Preparation and Characterization of Bioblends from Gelatin and Linear Low Density Polyethylene (LLDPE) by Extrusion Method

Abstract

Bioblends are composites of at least one biodegradable polymer with a non-biodegradable polymer. Successful development of bioblends requires that the biodegradable polymers be compatible with other component biodegradable/synthetic (non-biodegradable) polymers. Bioblends from LLDPE and gelatin were prepared by extrusion and hydraulic heat press technique. The gelatin content in the bioblends was varied from 5 to 20 wt%. Various physico-mechanical properties such as tensile, bending, impact strength (IS), thermal ageing and soil degradation properties of the LLDPE/gelatin bioblends with different gelatin contents were evaluated. The effect of thermal ageing on mechanical properties was studied. The mechanical properties such as tensile modulus (TM), bending strength (BS), bending modulus (BM) were found to increase with increasing gelatin content up to 20 wt%, however tensile strength (TS) and elongation at break (%E _b) were decreased with increasing gelatin content. Impact strength value increased with increasing gelatin content up to 10 wt% and then decreased slightly with increasing gelatin content. The blend containing 20 wt% gelatin showed relatively better mechanical properties than other blends. The values of TS, TM,%E _b, BS, BM and IS for the bioblend with 20 wt% gelatin content are 5.9MPa, 206.3MPa, 242.6%, 12.1MPa, 8 MPa and 13.7 J/cm², respectively. Water uptake increases with increasing soaking time in water and weight loss due to soil burial also increases with increasing gelatin content in the blends but both are significantly lower than that of pure gelatin sheet. Weight loss values after thermal ageing increase with time, temperature and increasing gelatin content in the blend but are much lower than pure gelatin. Mechanical properties such as TS, TM are increased and %E _b is decreased after thermal ageing at 60°C for 30 min. Consequently, among all of the bioblends prepared in this work the blend having 20% gelatin content yields properties such that it can be used as a semi-biodegradable material.     

Biodegradable PLA-based composites modified by POSS particles

ABSTRACT

The poly(lactic acid)(PLA)/aliphatic poly(carbonate)(PPC)/polyethylene glycol-polyhedral oligomeric silsesquioxane (PEG-POSS) composites were prepared by reactive melting extrusion. The effect of various components on the mechanical, thermal, rheological, and hydrophilic properties of composites was systematically studied by means of various characterization methods. The results showed that, with the increase of PPC content, the toughness of composites improves significantly, while the strength decreases. Reactive extrusion and adding PEG-POSS could enhance the compatibility and adjust the crystallization of composites effectively. When the proportion of PPC and PEG-POSS in composites is 20-40wt% and 4wt%, respectively, the composites own the best comprehensive performance.     

Perforative silica microsphere-modified phenolphthalein-based poly(arylene ether sulfone) composites: tensile and thermal properties

Perforative silica microspheres (PSMs) were prepared by an emulsion method coupled with sol–gel technology and phase separation. Next, phenolphthalein-based poly(arylene ether sulfone)/PSM composites (PES-C/PSM) were fabricated. PSM was characterized by scanning electron microscopy (SEM) and the Brunauer–Emmett–Teller (BET) method. The as-synthesized PSM exhibited a spherical shape with an external diameter of 2–10 µm, surface area of 166.5 m²/g and pore volume of 1.35 cm³/g. SEM and energy-dispersive spectroscopy (energy-dispersive spectroscopy) were used to characterize the morphology and the composition of the composite, respectively. Both SEM and energy-dispersive spectroscopy results revealed that the PES-C polymer chains penetrated into the PSM pores. In addition, the effect of PSM weight content on the mechanical properties and thermal stability of the composites was characterized by tensile tests and thermal analysis, respectively. A 19% increase in tensile strength and a 29% increase in breaking elongation of PES-C were achieved by the addition of 0.50 wt% PSM. Moreover, the thermal oxidative stability of PES-C was remarkably improved with the incorporation of PSM. Compared with pristine PES-C, the final degradation temperature was enhanced by 42 °C at 1.0 wt% PSM loading. Our studies have indicated that PSM is a kind of promising reinforcement for improvement of tensile and thermal properties of engineering plastics.     

Effect of Ultraviolet Radiation on the Mechanical and Dielectric Properties of Hessian Cloth/PP Composites with Starch

Hessian cloth (jute fabrics) reinforced poly(propylene) (PP) composites (45 wt% fiber) were prepared by compression molding and the mechanical properties were evaluated. Jute fabrics and PP sheets were treated with UV radiation at different intensities and then composites were fabricated. It was found that mechanical properties of the irradiated jute and irradiated PP-based composites were found to increase significantly compared to that of the untreated counterparts. Irradiated jute fabrics were also treated with aqueous starch solution (1–5%, w/w) for 2–10 min. Composites made of 3% starch-treated jute fabrics (5 min soaking time) and irradiated PP showed the best mechanical properties. Tensile strength, bending strength, tensile modulus, bending modulus and impact strength of the composites were found to improve 31, 41, 42, 46 and 84% higher over untreated composites. Water uptake, thermal degradation and dielectric properties of the resulting composites were also performed.     

The Processing and Characterization of MWCNT/Epoxy and CB/Epoxy Nanocomposites Using Twin Screw Extrusion

This paper presents results of the processing of nanocomposites based on epoxy and nanofillers, namely multiwalled carbon nanotubes (up to 10 wt%) and carbon black (up to 15 wt%). The twin screw extruded nanocomposites showed increases in electrical and thermal conductivities, tensile strength, microhardness and glass transition temperature. Electrical conductivity increased on the order of 10¹¹ at 10 wt% of nanotubes loading and at 15 wt% of carbon black. Greater increases in thermal and mechanical properties were observed in cases of nanotube-dispersed composites more so than others. SEM and AFM were used to examine the dispersion of the fillers.     

Effect of SNNWS content on the microstructure and properties of SNNWS/Si-C-N ceramic composites via PIP

Si-C-N ceramic composites containing well distributed silicon nitride nanowires (SNNWs) were fabricated by die-pressing and precursor infiltration and pyrolysis process at a low temperature. The structure, composition, mechanical and thermophysical properties of the composites were investigated. The results show that the composites consisted of amorphous SiCN, α-Si₃N₄ and α-cristobaslite. The composites with different contents of SNNWs possessed a density of 2.02–2.07 g cm^?3 and open porosity of 7.9–9.9%. SNNWs can effectively restrain the contraction of matrix with a decrease by 25% in linear shrinkage. The composites with 3 wt% SNNWs owned the highest flexural strength (83.7 MPa) and elastic modulus (54.0 GPa) at room temperature, which increase by 13.2% and 62.3% respectively, compared with pure SiCN ceramics. The SNNWs displayed good reinforcement function at high temperature due to the fact that the composites with 7 wt% SNNWs had a 96.8% retention rate of bending strength at 1200 °C. The composites had relatively low coefficient of thermal expansion and thermal diffusivity which were less than 2.2 × 10^?6 K^?1 and 0.62 mm² s^?1, respectively.     

Mechanical and Morphological Properties of Polypropylene and Regenerated Tire-Rubber Blends

Mechanical properties and morphology of blends prepared from polypropylene (PP) and 5–20 wt% of regenerated tire-rubber (RgR) were studied. The samples were prepared in a twin-screw extruder. The addition of maleic anhydride-functionalized polypropylene (PP-g-MAH) was also investigated. Tensile and flexural moduli, tensile strength at break, elongation at break and Izod impact resistance at 23°C were increased by the addition of 15 wt% of regenerated rubber and 5 wt% of PP-g-MAH. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses showed some interaction between PP and RgR and considerable modification of the compatibilized mixture morphology. The fracture surface of the blend with PP-g-MAH showed a better interaction between the PP matrix and the regenerated rubber domains, for all blends. Well-dispersed particles of the rubber in the polypropylene matrix were observed. DSC showed that PP crystallizes on cooling at lower temperatures as the RgR content increases. The decrease in crystallization temperature is more evident for blends with 5 wt% PP-g-MAH.     

Pinecone particles filled polybenzoxazine composites: Thermomechanical and mechanical properties

In the current study, 1 wt%, NaOH treated pine cone (ATPC) particles composites with bisphenol-A aniline based benzoxazine (BA-a) matrix were prepared by isothermal compression method. Ultimate impacts of ATPC reinforcement on the thermomechanical, tensile, flexural, and impact properties of the composites were studied by using a dynamic mechanical analyzer (DMA), a Universal testing machine, and a Tinius-Olsen impact device, respectively. The thermal stability of ATPC particles was remarkably increased, TGA confirmed that particles will not be degraded during the curing. The DMA results of 30 wt% ATPC reinforced composites confirmed that the glass transition temperature, storage modulus, and loss modulus were 22 ° C, 2510, and 250 MPa higher than the neat matrix, respectively. In addition, the impact strength of the 30 wt% ATPC reinforced composites was nearly 3 times higher than the neat matrix, which confirmed that the matrix's brittleness is reduced, similar observation was confirmed by the Brostow and coworkers empirical model. Moreover, a gradual rise in the tensile and flexural properties was also recorded. We can easily conclude from the studied parameters that the ATPC particles can be used as a sustainable agro-waste in polymeric composites.     

Improvement of heat resistance and mechanical properties of epoxy resin with nano-Cu-Ni supported RGO

This study reports the synthesis and characterization of epoxy resin/redox graphene/nano-copper-nickel (EP/RGO/Cu-Ni) composites. The RGO/Cu-Ni was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Using dynamic thermodynamic analysis (DMA), the glass transition temperature (Tg) of the modified epoxy resin was increased by 21°C compared to EP. The addition of 1.3 wt% RGO/Cu-Ni to the epoxy matrix resulted in an increase of 79.6% and 161.3% respectively in the tensile strength and impact strength of the new material. Finally, the excellent mechanical properties of EP/RGO/Cu-Ni nanocomposites contribute to the research and development of new high-performance polymer materials.