Evaluation of properties of unsaturated polyester/acetylated hydroxypropyl guar gum composites

Guar gum is a naturally occurring galactomannan, which is extremely hydrophilic in nature. Hydroxypropyl guar gum (HPG) was subjected to acetylation using acetic anhydride and pyridine. The effect of the reduction in the hydrophilic nature of the polymer on its filler properties was studied by using the derivatized guar gum as filler in an unsaturated polyester composite. The effect of degree of substitution and the concentration of filler on the rheological, chemical, and mechanical properties of the composites were studied. Results indicated that an increase in the acetate content in the HPG resulted in an increased polymer–filler interaction. However, the composites resulting from these derivatized HPGs showed reduced mechanical properties. This decrease in the mechanical properties were attributed to the decrease in the hydrogen bonding in the filler particles, thus reducing the cohesiveness and strength of the filler particles themselves. Thus, polysaccharides can be used as fillers but chemically modifying them results in a change in the basic nature of the filler itself and is not just restricted to surface modification as is the case of inorganic fillers and fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Evaluation of mechanical properties of acrylated guar gum – unsaturated polyester composites

Guar gum (GG) and its derivatives are commonly used in aqueous solutions as rheology modifiers. The use of polysaccharides as fillers in thermoset polymer composites has as yet not received that attention attributed to other materials. In the present study GG and the effect of acrylation on its filler properties were evaluated. Unsaturated polyester composites were evaluated for their mechanical properties as well as solvent resistance and water absorption. It was observed that the acrylate derivatives with the highest degree of substitution resulted in composites with the best mechanical properties as well as increased toluene and water resistance. Thus, polysaccharides could be used as reinforcing fillers in thermoset composites.     

Use of construction and demolition wastes as mineral fillers in hybrid wood–polymer composites

The recycling of construction materials has been the subject of much research in past years. In this study, the use of construction and demolition wastes (CDWs) as mineral fillers in hybrid wood–polymer composites was studied. Two types of waste materials were used as fillers in the composites: (1) a mixture consisting of waste mineral wool (MW) and plasterboard (PB) and (2) mixed CDWs. The performance of the composites was evaluated from their mechanical properties and water‐absorption behavior. We found in the study that the addition of mineral fillers decreased the flexural strength and modulus values of the wood–polypropylene (PP) composites. On the other hand, the exchange of part of the wood with a mineral filler resulted in an increase in the impact strength of the composite. The composite manufactured with the combination of MW and PB had the lowest water absorption. The decrease in wood loading resulted in improved dimensional stability in the hybrid wood–mineral filler–PP composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43412.     

Biopolymers as effective fillers in natural rubber: Composites versus biocomposites

Biocomposites of natural rubber (NR) blends were prepared with a variety of fillers obtained from renewable resources by a mastication technique. They were characterized for their mechanical properties and morphologies and compared with composites of the conventional filler carbon black (c‐black). The biopolymers exhibited an interesting trend and imparted strength to NR that was quite comparable to c‐black. Up to 30 phr of the fillers could be successfully incorporated; this led to enhancements in the mechanical strength. The properties were found to vary with the type and ratio of filler, namely, starch, cellulose, and chitin. The optimum mechanical strength of the biocomposites was observed at 10 phr. The results were interpreted on the basis of the morphology by scanning electron microscopy, which revealed strong filler–polymer interactions. The moisture‐uptake characteristics of the composites were studied. It was found that addition of biofillers did not lead to a significant increase in the moisture absorption. Furthermore, as the adhesion between the polymer matrix and fillers increased, the water uptake decreased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Filler effect of potato starch and urea on degradation of linear low density polyethylene composites

Starch and urea are used as fillers, owing to their good mechanical and degradable properties, in linear low density polyethylene matrix. Composites of varying amount of starch and urea composition are prepared. Various properties like tensile strength, elongation at break, Young's modulus, shore-D hardness, and water absorption are studied. The tensile strength, elongation at break, Young's modulus, and Shore-D hardness decrease with maleic anhydride treatment of starch and urea for polymer composites. On increasing the amount of filler in the composites, the mechanical properties decrease. The soil-burial treatment of these composites also causes reduction in these properties. The absorption of water increases for one month and decreases later during the period 2–5 months. The increase in absorption might be due to the onset of degradation of composites. The degradation of the composites is also observed by the presence of grooves and pits in optical micrographs of soil-exposed composites.     

Raw and chemically treated bio-waste filled (Limonia acidissima shell powder) vinyl ester composites: Physical,mechanical, moisture absorption properties,and microstructure analysis

The rapid growth of environmentally sustainable and eco-friendly materials tends to the utilization of biowastes as filler in polymer matrix composites. The particulate composite with improved wettability of fillers and advanced approach can evolve polymer composites that exhibit promising applications in packaging, automobile, marine, construction, and aerospace. In the present work, one of the biowaste fillers were synthesized from Limonia acidissima shells via a top-down approach (pulverizing) and the surfaces were chemically modified using sodium hydroxide (NaOH) before they were used as fillers in vinyl ester polymer composites by different weight percentage (0, 5, 10, 15, and 20 wt%). The prepared particulate composites were characterized by mechanical properties, moisture absorption behavior, and morphology. At different filler loading the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, hardness, density, and moisture intake tests were performed. The results reveal that the properties increased for composites filled with alkaline treated fillers for the same filler loading and found to be higher at filler loading of 15 wt%. The morphological analysis confirms the better interfacial bonding between alkali-treated particles and matrix due to the removal of non-cellulose materials from the surface of the particles.     

The Physical Properties of Oil Palm Empty Fruit Bunch (EFB) Composites Made from Various Thermoplastics

Abstract

Oil palm empty fruit bunch (EFB)-based composites were produced using different types of thermoplastic as matrices. The composites were produced by using an internal mixer. The mechanical and water absorption properties of composites were investigated. Overall, the incorporation of EFB into the polymer matrix has resulted in the reduction of flexural strength. The poor performance has been attributed to the poor filler-matrix interaction. Both flexural and tensile modulus of PE and PP composites have been improved upon the addition of fillers, however, both PS and PVC composites showed a decreasing trend. Tensile strength and elongation at break results for all composites have been reduced as the result of incorporation of filler. This has been attributed to the poor filler-matrix interaction or compatibility, size irregularity and also decreased ductile deformation. Water absorption and thickness swelling increased as the filler loading is increased. This has been attributed to the presence of hyrophillic hydroxyl groups of the filler.     

Production of filled hydrogels by mechanochemically induced polymerization

Silica nanoparticles functionalized with polyvinylpyrrolidone (PVP) were obtained by the grinding/mechanical activation of quartz or nonfunctionalized silica nanoparticles in a stirred media mill in the presence of 1‐vinyl‐2‐pyrrolidone, as proven by Fourier transform infrared spectroscopy. The polymer layer thickness formed on the silica nanoparticles after 8 h of mechanical activation in the absence of polymerization initiators amounted to about 10 nm, as derived from shear rheology. The silica nanoparticles functionalized with the hydrophilic PVP by mechanochemical polymerization reaction were used as fillers for hydrogels based on poly(hydroxyethyl methacrylate) (polyHEMA). The water absorption, release properties, and mechanical properties of the polyHEMA–silica composites were measured as functions of the filler content and particle size of the filler. PolyHEMA samples containing 20 wt % of the functionalized silica particles exhibited a higher maximum water absorption than the unfilled polymer; this showed that the hydrophilic interface between the filler and the matrix improved the water absorption. The release of methylene blue from the polyHEMA–silica composites was governed by diffusion and was almost unaffected by the silica particles. The values for the storage modulus and loss modulus of the polyHEMA–silica composites increased with growing filler content. For constant filler content, the storage modulus increased with decreasing particle diameter of the filler; this showed that the reinforcing effect increased with the interface between the filler particles and the matrix polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of alkali treatment and filler size on the properties of sawdust/UPR composites based on recycled PET wastes

In this study, natural sawdust fillers from acacia were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene terephthalate (PET) waste bottles to prepare sawdust/UPR composite. PET wastes were recycled through glycolysis and depolymerized to produce a formulation for the resin. The effects of alkali treatment, filler content, and filler size on the tensile, flexural, hardness, and water absorption of the composites were investigated. The results show that the modulus of both tensile and flexural increased with increasing filler contents, but the tensile and flexural strength of composites decreased. The size of sawdust also played a significant role in the mechanical properties, with smaller size sawdust producing higher strength and modulus. This is due to the greater surface area for filler–matrix interaction. The results also show that alkali treatment causes a better adhesion between sawdust and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Evaluation of biodegradability of epoxy‐guar gum composites

Epoxy composites incorporating natural components have been mainly limited to the use of natural fibers. However, there have been a few instances where polysaccharides have been used as particulate fillers in thermoset compositions. The present study investigated the effect of guar gum/hydroxypropyl guar gum as a filler on the degradative properties of epoxy composites at various filler concentrations, with reference to fungal degradation and soil burial tests. It was found that at higher filler concentrations, the degradation increased. Composites based on hydroxypropyl guar gum showed increased degradation initially but on prolonged exposure to the fungal environment, the difference between guar gum and the hydroxypropyl guar gum‐based composites was found to be marginal. Microscopic evaluation of the composites showed that the degradation occurred at both the composite surface and in the bulk. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

矿物填料填充聚乙烯/麦秸杆复合材料性能比较

以麦秸杆纤维(WSF)和高密度聚乙烯(PE-HD)为原料,以白云石粉、硅灰石粉及滑石粉为填充料,通过熔融混炼及注射成型的方法制备了PE-HD/WSF/填料复合材料,并通过差示扫描量热仪、扫描电子显微镜和电子万能试验机等考察分析了填料种类及含量对复合材料结晶性能、微观形貌和力学性能等的影响.结果表明,在WSF的含量为40...     

Effect of single‐mineral filler and hybrid‐mineral filler additives on the properties of polypropylene composites

The present study was carried out to determine the filler characteristics and to investigate the effects of three types of mineral fillers (CaCO₃, silica, and mica) and filler loadings (10–40 wt%) on the properties of polypropylene (PP) composites. The characteristics of the particulate fillers, such as mean particle size, particle size distribution, aspect ratio, shape, and degree of crystallinity were identified. In terms of mechanical properties, for all of the filled PP composites, Young's modulus increased, whereas tensile strength and strain at break decreased as the filler loading increased. However, 10 wt% of mica in a PP composite showed a tensile strength comparable with that of unfilled PP. Greater tensile strength of mica/PP composites compared to that of the other composites was observed because of lower percentages of voids and a higher aspect ratio of the filler. Mica/PP also exhibited a lower coefficient of thermal expansion (CTE) compared to that of the other composites. This difference was due to a lower degree of crystallinity of the filler and the CTE value of the mica filler. Scanning electron microscopy was used to examine the structure of fracture surfaces, and there was a gradual change in tensile fracture behavior from ductile to brittle as the filler loading increased. The nucleating ability of the fillers was studied with differential scanning calorimetry, and a drop in crystallinity of the composites was observed with the addition of mineral filler. Studies on the hybridization effect of different (silica and mica) filler ratios on the properties of PP hybrid composites showed that the addition of mica to silica‐PP composites enhanced their tensile strength and modulus. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Water uptake and mechanical characteristics of natural filler–polypropylene composites

Water uptake characteristics and some mechanical properties of polypropylene composites containing three types of natural fillers, purified α‐cellulose, wastepaper fibers, and wood flour were studied. The fiber contents were 15, 25, and 35% by weight. Two percent maleic anhydride polypropylene (MAPP) was also added to the mix, as the compatibilizer agent. Mixing process was performed in a Brabender Plasticorder until a constant torque was reached. Composites made out of these combinations were then pressed in a laboratory press and ASTM standard test specimens were cut out of the sheets. Water absorption and tensile tests were performed on these specimens. The results showed a significant difference between the various filler types regarding water uptake. Water uptake also increased by the increase in filler content. Tensile strength and elongation at break in composites declined when compared with pure polypropylene, but their modulus of elasticity increased. Among the three types of fillers, no significant discrepancies were observed in terms of improving mechanical properties in composites. Filler content increase had no drastic effect regarding strength improvement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 941–946, 2003     

Tensile properties of carbon filled liquid crystal polymer composites

Electrically and thermally conductive resins can be produced by adding carbon fillers. Mechanical properties such as tensile modulus, ultimate tensile strength, and strain at ultimate tensile strength are vital to the composite performance in fuel cell bipolar plate applications. This research focused on performing compounding runs followed by injection molding and tensile testing of carbon filled Vectra A950RX liquid crystal polymer composites. The four carbon fillers investigated included an electrically conductive carbon black, thermocarb synthetic graphite particles, and two carbon fibers (Fortafil 243 and Panex 30). For each different filler type, resins were produced and tested that contained varying amounts of these single carbon fillers. The carbon fiber samples exhibited superior tensile properties, with a large increase in tensile modulus over the base polymer, and very low drop in the ultimate tensile strength as the filler volume fraction was increased. The strain at the ultimate tensile strength was least affected by the addition of the Panex carbon fiber but was significantly affected by the Fortafil carbon fiber. In general, composites containing synthetic graphite did not perform as well as carbon fiber composites. Carbon black composites exhibited poor tensile properties. POLYM. COMPOS., 29:15–21, 2008. © 2007 Society of Plastics Engineers     

Crystallization and melting of highly filled polypropylene composites prepared with surface‐treated fillers

Polypropylene (PP) composites with high filler content have been prepared with surface‐treated fillers. The effect of the filler is twofold; nucleation of crystallization occurs, though the PP is also adsorbed onto the filler thereby retarding its motion. Differential scanning calorimetry has been used to study the crystallization of the PP. Melting and recrystallization during melting has been characterized by differential scanning calorimetry. The properties of the composites are more than an additive combination of the filler and polymer. In the case of highly filled composites, the morphology of the PP is important in limiting brittleness and for the strength of the interface between filler and polymer. Surface treatment of the filler has been found to have a significant control over the morphology and properties of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1942–1948, 2001     

Polypropylene (PP)–Acacia mangiumcomposites: the effect of acetylation on mechanical and water absorption properties

Acacia mangiumwood flour (AMWF)–polypropylene (PP) composites were produced at different filler loading (20, 30, 40, and 50 w/w) and mesh no. (35, 60, 80, and 100 mesh). The AMWF–PP composites (using unmodified or modified wood flour) were compounded using a Haake Rheodrive 500 twin screw compounder. The mechanical and water absorption (WA) properties of modified (only at mesh no. 100) and unmodified AMWF–PP composites were investigated. Increase in the mesh number (35–100) of the unmodified AMWF showed increased flexural and impact properties. Flexural modulus exhibited higher properties as the filler loading increased (20–50). However, flexural and impact strength showed the opposite phenomenon. Water absorption and thickness swelling increased as the mesh number and filler loading increased. This has been attributed to the presence of hydrophilic hydroxyl groups of the filler. Modified AMWF–PP composites exhibited higher mechanical properties and good water resistance when compared to unmodified AMWF–PP composites at all values of filler loading. The evidence of the failure mechanism (from impact strength) of the filler–matrix interface was analyzed using scanning electron microscope.     

The effect of multiscale hybridization on the mechanical properties of natural fiber-reinforced composites

The main objective of this work was to investigate the effect of reinforcements at different scales on the mechanical properties of natural fiber-reinforced composites. Pure jute and interlaminar hybrid jute/glass fiber-reinforced polymer composites were fabricated. Different types of fillers in two weight fractions (1 and 3 wt. %) were used as second reinforcements in the hybrid jute/glass composites. Tensile, flexural, and impact tests were performed. It was found that the macroscale inter-play hybridization significantly improved the mechanical properties of the pure jute fiber based composites. When the fillers are used as second hybridization, the modified composites presented higher mechanical properties when compared to pure jute composites. However, the effect of fillers on the mechanical properties of the hybrid composites presented various trends due to the interaction between several factors (i.e., particle scale, content, and nature), which cannot always be separated. Increasing the synthetic filler content improved the tensile properties of the filled hybrid composites, while increasing the natural filler content worsen the tensile properties. The flexural strength of the multiscale hybrid composites was improved, while the impact properties were negatively affected.     

Influence of carbon black in polychloroprene organoclay nanocomposite with improved mechanical,electrical and morphology characteristics

Abstract

The effect of carbon black on nanoclay filled polychloroprene (CR) composites has been investigated. The nanoclay loading is fixed at 5 part per hundred rubbers (phr), and carbon black loading varied from 5 to 20 phr in rubber compounds. The rubber nanocomposites are prepared in laboratory by mixing in two-roll mill. The addition of nanoclay enhances mechanical properties especially tear strength and decreases water absorption without change in electrical properties compared to gum rubber vulcanisates. Wide angle X-ray diffraction and transmission electron microscopy are used to study the microstructure of CR nanocomposites. The addition of 5 parts of nanoclay to 15 phr carbon black filled samples shows synergistic effect between the fillers and suggests that the reinforcement is due to a more developed filler network formation in hybrid filler system than that in single phase filler. Significant improvement in mechanical, electrical and low water absorption properties has been obtained with these nanoclay and carbon black filled rubber nanocomposites. The paper concludes that nanocomposites containing a mixture of organoclay and carbon black in right proportion can be a substitute for rubber components used in underwater cable and device encapsulation applications.     

Injection molding of biodegradable polyester blends filled with mineral and sustainable fillers: Performance evaluation

This research focuses on the melt processing of biocomposites from a biodegradable polymer blend mixed with hybrid fillers through injection molding technique. An optimized blend ratio (60/40 wt%) poly(butylene succinate-co-butylene adipate) (PBSA) and poly(butylene adipate-co-terephthalate) (PBAT) demonstrated promising results after blending with a mixture of walnut shell powder (WSP), corn starch and talc in various proportions for use in rigid packaging. The addition of hybrid fillers (i) 10% WSP with 15% talc and (ii) 5% WSP with 5% starch and 15% talc to the polymer blend (60%PBSA/40%PBAT) improved tensile modulus (160% and 162%, respectively) and flexural modulus (147% and 153%, respectively) because of the dispersion of stiffer talc and WSP. Following the addition of fillers, tensile strength of the composites decreased. However, flexural strength improved significantly after filler introduction because of better stress transfer ability. Rheological analysis of filled composites with starch or WSP (25%) depicted similar characteristics of the polymer blend, indicating lower viscosity than hybrid composites. The abundant hydroxyl groups in starch explained the increased water absorption and decreased contact angle compared with other composites. This research's novelty encompasses utilizing low-cost biomasses with mineral filler into an under-researched biodegradable polymer blend suitable for single-use rigid packaging applications.     

Agrofillers in polypropylene composites: A relationship between the density and the mechanical properties

One of the most interesting properties of agrofilled polymer composites is their light weight. Polypropylene composites containing six different agrofillers were prepared in a mixer, and their properties were examined in terms of the density of the fillers and composites. The densities of the composites increased with the level of filler but did not show a direct relationship with the density of the fillers used. This probably happened because of the different degrees of filler densification during processing. The composites showed decreased tensile strength and increased elastic modulus with filler loads, and the specific mechanical properties showed similar trends. However, the addition of maleated polypropylene improved the tensile strength and decreased the density; this improved the specific properties of the composites filled with cane, wood, and bamboo. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010