Polypropylene/silica micro‐ and nanocomposites modified with poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)

The effects of different silica loadings and elastomeric content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with 5, 10, 15, and 20 vol % of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) SEBS added to total composite volume were investigated. Four silica fillers differing in size (nano‐ vs. micro‐) and in surface properties (untreated vs. treated) were chosen as fillers. Elastomer SEBS was added as impact modifier and compatibilizer at the same time. The morphology of ternary polymer composites revealed by light and scanning electron microscopies was compared with morphology predicted models based on interfacial properties. The results indicated that general morphology of composite systems was determined primarily by interfacial properties, whereas the spherulitic morphology of polypropylene matrix was a result of two competitive effects: nucleation effect of filler and solidification effect of elastomer. Tensile and impact strength properties were mainly influenced by combined competetive effects of stiff filler and tough SEBS elastomer. Spherulitic morphology of polypropylene matrix might affect some mechanical properties additionally. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41486.     

A conductive foam: Based on novel poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer filled by carbon black

In this article, a conductive foam based on a novel styrene‐based thermoplastic elastomer called poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene‐b‐butadiene‐b‐styrene) tri‐block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross‐linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180°C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30–50 µm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 × 10⁶ to 6.20 × 10⁷ cells/cm³) and a rapid thinning of the cell walls (from 45.3 to 1.4 µm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48–0.09 g/cm³ and the volume resistivity of 3.1 × 10³?2.5 × 10⁵ Ω cm can be easily prepared in this study. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41644.     

Preparation,characterization, and improvement of hollow epoxy particle‐toughened vinyl ester composites for high‐end applications

Spherical hollow epoxy particles (HEPs) that can serve as advanced reinforcing fillers for vinyl ester thermosets were prepared using the water‐based emulsion method. The HEP fillers were incorporated into the vinyl ester matrices at different loading amounts, ranging from 0 to 9 wt %, to reinforce and toughen the vinyl ester composite. The optimum mechanical properties of the HEP‐toughened epoxy composite can be achieved by the addition of 5 wt % HEP filler into the vinyl ester matrices. The toughening and strengthening of the epoxy composites involved the interlocking of vinyl ester resins into the pore regions on the HEP fillers. The toughening and interlocking mechanisms of HEP‐toughened vinyl ester composites were also proposed and discussed. The addition of HEP fillers into vinyl ester matrices increased the glass transition temperature (T_g) and thermal stability of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of quartz‐fiber‐cloth‐reinforced,polymerization‐of‐monomer‐reactant‐type polyimide substrates with a high impact strength

A series of novel quartz‐fiber‐cloth‐reinforced polyimide substrates with low dielectric constants were successfully prepared. For this purpose, the A‐stage polyimide solution was first synthesized via a polymerization‐of‐monomer‐reactant procedure with 2,2′‐bis(trifluoromethyl)benzidine and 3,3′,4,4′‐oxydiphthalic anhydride as the monomers, and cis?5‐norbornene‐endo‐2,3‐dicarboxylic anhydride as the endcap. Then, an A‐stage polyimide solution (TOPI) was impregnated with quartz‐fiber cloth (QF) to afford the prepregs, which were thermally molded into the final substrate composites. The influence of the curing temperature and the resin content on the mechanical properties of the composite were examined. The composites exhibited a high glass‐transition temperature over 360°C, a low and steady dielectric constant below 3.2 at a test frequency of 1–12 GHz, and a volume resistance over 1.8 × 10¹⁷ Ω cm. Meanwhile, they also showed a high mechanical strength with flexural and impact strengths in ranges 845–881 MPa and 141–155 KJ/m², respectively. The excellent mechanical and thermal properties and good dielectric properties indicated that they are good candidates for integrated circuit packaging substrates. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42358.     

The effect of BMP‐2 and VEGF loading of gelatin‐pectin‐BCP scaffolds to enhance osteoblast proliferation

A composite scaffold of gelatine (Gel)‐pectin (Pec)‐biphasic calcium phosphate (BCP) was successfully fabricated. Growth factors such as bone morphogenetic protein‐2 (BMP‐2) and vascular endothelial growth factor (VEGF) were loaded into the Gel‐Pec‐BCP hydrogel scaffolds by freeze‐drying. The surface morphology was investigated by scanning electron microscopy, and BCP dispersion in the hydrogel scaffolds was measured by energy dispersive and X‐ray diffraction spectroscopy. The results obtained from Fourier transform infrared spectroscopy and quantitative measurements showed successfully loading of BMP‐2 and VEGF into the Gel‐Pec‐BCP hydrogel scaffolds. In addition MC3T3‐E1 preosteoblasts were cultivated on the three types of scaffolds to investigate the effects of BMP‐2 and VEGF on cell viability and proliferation. The Gel‐Pec‐BCP scaffolds loaded with VEGF and BMP‐2 demonstrated more cell spreading and proliferation compared to those of the Gel‐Pec‐BCP scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41241.     

Low dielectric and high thermal conductivity epoxy nanocomposites filled with NH2‐POSS/n‐BN hybrid fillers

Hybrid fillers of mono‐amine polyhedral oligomeric silsesquioxane/nanosized boron nitride (NH₂‐POSS/n‐BN) were performed to fabricate NH₂‐POSS/n‐BN/epoxy nanocomposites. Results revealed that the dielectric constant and dielectric loss values were decreased with the increasing addition of NH₂‐POSS obviously, but increased with the increasing addition of BN fillers. For a given loading of NH₂‐POSS (5 wt %), the thermal conductivities of NH₂‐POSS/n‐BN/epoxy nanocomposites were improved with the increasing addition of n‐BN fillers, and the thermal conductivity of the nanocomposites was 1.28 W/mK with 20 wt % n‐BN fillers. Meantime, the thermal stability of the NH₂‐POSS/n‐BN/epoxy nanocomposites was also increased with the increasing addition of n‐BN fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41951.     

Preparation of O‐hydroxypropyl‐N‐butyl chitosan under microwave irradiation

O‐Hydroxypropyl‐N‐butyl chitosan (C₄‐HPCS) was prepared by microwave irradiation and phase‐transfer catalysis; this consisted of two steps: (1) the synthesis of O‐hydroxypropyl chitosan (HPCS) with chitosan and propylene oxide and (2) the synthesis of C₄‐HPCS with HPCS and 1‐butyl bromide. The results of the experiment are as follows: Fourier transform infrared spectroscopy and ¹H‐NMR displayed the characteristic peaks of C₄‐HPCS, thermogravimetric analysis showed that C₄‐HPCS was stable until 240°C, the critical micelle concentration was 0.025 wt %, the surface tension was equal to 65.70 ± 0.09 mN/m, the hydrophile–lipophile balance number value was 13.55, and the emulsifying power, foaming expansion, and foaming volume stability were 73.10, 45, and 94 wt %, respectively. This indicated that C₄‐HPCS had superior surface performance and more excellent hydrophilicity. In addition, the microwave irradiation and phase‐transfer catalysis used in the experiment were considered to be more environmentally friendly and time‐saving methods. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41527.     

Fabrication and biocompatibility of porously bioactive scaffold of nonstoichiometric apatite and poly(ε‐caprolactone) nanocomposite

Bioactive nanocomposite of nonstoichiometric apatite (ns‐AP) and poly(ε‐caprolactone) (PCL) was synthesized and its porous scaffold was fabricated. The results show that the hydrophilicity and cell attachment ratio on the composite surface improved with the increase of ns‐AP content in PCL. The composite scaffolds with 60 wt % ns‐AP content contained open and interconnected pores ranging in size from 200 to 500 μm and exhibit a porosity of around 80%. In addition, proliferation of MG₆₃ cells on the composite scaffolds significantly increased with the increase of ns‐AP content, and the level of alkaline phosphatase (ALP) activity and nitric oxide (NO) production of the cells cultured on the composite scaffold were higher than that of PCL at 7 days, revealing that the composite scaffolds had excellent in vitro biocompatibility and bioactivity. The composite scaffolds were implanted into rabbit mandible defects, the results suggest that the introduction of ns‐AP into PCL enhanced the efficiency of new bone formation, and the ns‐AP/PCL composite exhibited in vivo good biocompatibility and osteogenesis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nano‐SiO2/PMMA‐PU composite particles with core‐shell structure via emulsion polymerization and their application in epoxy resin

A novel method of nano‐SiO₂/poly(methyl methacrylate)(PMMA)‐polyurethane(PU) composite particles modifying epoxy resin is reported. The composite particles with the obvious core‐shell structure were prepared by emulsion polymerization of PMMA and PU prepolymer on the surface of nano‐SiO₂. The diameter of the composite particles was 50–100 nm with dark core SiO₂ (30–60 nm) and light shell polymer of PMMA and PU (20–30 nm); moreover, PU was well distributed in PMMA with about 10 nm diameter. After nano‐SiO₂ was encapsulated by PMMA and PU, the Si content on the surface decreased rapidly to 2.08% and the N content introduced by PU was about 1.27%. The ratio of polymer to original nano‐SiO₂ (f_p), the grafting ratio of polymer to original nano‐SiO₂ (f_r) and the efficiency grafting ratio of polymer (f_e) were, respectively, about 116.7%, 104.4%, and 89.5%. The as‐prepared composite particles were an effective toughness agent to modify epoxy resin, and the impact strength of the modified epoxy resin increased to 46.64 kJ m^?2 from 19.12 kJ m^?2 of the neat epoxy resin. This research may enrich the field of inorganic nanoparticles with important advances toward the modification for polymer composite materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41919.     

Self‐Generating High‐Temperature Oxidation‐Resistant Glass‐Ceramic Coatings for C–C Composites Using UHTCs

Carbon–carbon (C–C) composites are ideal for use as aerospace vehicle structural materials; however, they lack high‐temperature oxidation resistance requiring environmental barrier coatings for application. Ultra high‐temperature ceramics (UHTCs) form oxides that inhibit oxygen diffusion at high temperature are candidate thermal protection system materials at temperatures >1600°C. Oxidation protection for C–C composites can be achieved by duplicating the self‐generating oxide chemistry of bulk UHTCs formed by a “composite effect” upon oxidation of ZrB₂–SiC composite fillers. Dynamic Nonequilibrium Thermogravimetric Analysis (DNE‐TGA) is used to evaluate oxidation in situ mass changes, isothermally at 1600°C. Pure SiC‐based fillers are ineffective at protecting C–C from oxidation, whereas ZrB₂–SiC filled C–C composites retain up to 90% initial mass. B₂O₃ in SiO₂ scale reduces initial viscosity of self‐generating coating, allowing oxide layer to spread across C–C surface, forming a protective oxide layer. Formation of a ZrO₂–SiO₂ glass‐ceramic coating on C–C composite is believed to be responsible for enhanced oxidation protection. The glass‐ceramic coating compares to bulk monolithic ZrB₂–SiC ceramic oxide scale formed during DNE‐TGA where a comparable glass‐ceramic chemistry and surface layer forms, limiting oxygen diffusion.     

Development and Characterization of Novel Biomimetic Composite Scaffolds Based on Bioglass‐Collagen‐Hyaluronic Acid‐Phosphatidylserine for Tissue Engineering Applications

Summary: Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies. The present study prepared novel biomimetic composite scaffolds with similar composite to natural bone using bioactive glass, collagen, hyaluronic acid, and phosphatidylserine. The microstructure, swelling ratio, biodegradability, and biomineralization characteristic of the composite scaffolds with and without hyaluronic acid and phosphatidylserine were compared and analyzed by SEM/EDAX, XRD, and FTIR techniques and in vitro test, and the properties can be influenced by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC)/N‐hydroxysuccinimide (NHS) crosslinking. The optimized properties of the crosslinked composite scaffolds observed in this study show the possibility of their use of bioactive and bioresorbable scaffolds in bone tissue engineering.

SEM micrographs of BG‐COL‐HYA‐PS composite scaffolds after immersion in SBF for 1 d.     

Silver‐nanoparticle‐Incorporated composite nanofibers for potential wound‐dressing applications

The aim of this study was to develop stable and porous poly(ethylene oxide) (PEO)–polycaprolactone blended and silver nanoparticle (Ag NP) incorporated composite nanofiber scaffolds as antibacterial wound dressings. A facile approach for the in situ synthesis of Ag NPs was explored. In this synthesis method, N,N‐dimethylformamide (DMF) was used as a solvent; it also acted as reducing agent for Ag NP formation. The stabilization of Ag NPs in the fibers was accomplished by PEO, which in turn acted as a reducing agent along with DMF. The successful synthesis of crystalline Ag NPs was confirmed by various characterization techniques. Thermogravimetric analysis, wettability, and surface roughness analysis of the nanofibers were done to examine the suitability of the scaffold for wound dressing. The as‐synthesized composite nanofibers possessed good roughness, wettability, and antibacterial potential against recombinant green fluorescent proteins expressing antibiotic‐resistant Escherichia coli. Thus, the nanofiber scaffold fabricated by this approach could serve as an ideal wound dressing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42473.     

Synthesis and properties of poly(sodium acrylate‐co‐2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid)/attapulgite as a salt‐resistant superabsorbent composite

A novel salt‐resistant superabsorbent composite was prepared by copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS) and attapulgite (APT). To enhance the swelling rate (SR) of the copolymer, sodium bicarbonate was used as a foaming agent in the course of copolymerization. Furthermore, for improving the properties of swollen hydrogel, such as strength, resilience and dispersion, the copolymer was surface‐crosslinked with glycerine and sodium silicate, and then the surface‐crosslinked copolymer was blended with aluminum sulfate and sodium carbonate in post treatment process. The influences of some reaction conditions, such as amount of AMPS, APT, and initiator, and neutralization degree of acrylic acid on water absorbency in 0.9 wt% NaCl aqueous solution both under atmospheric pressure (WA) and load (WA_P, P ≈ 2 × 10³ Pa) were investigated. In addition, the effect of them on SR was also studied. The WA and WA_P of the superabsorbent composite prepared under optimal conditions in 0.9 wt% NaCl aqueous solution were 52 g·g^?1 and 8 g·g^?1, respectively. Besides, the SR was fast, and it could reach 0.393 mL·(g·s)^?1. Moreover, the swollen hydrogel possessed excellent salt resistance, hydrogel resilience and dispersion. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Preparation and properties of porous poly(sodium acrylate‐co‐acrylamide) salt‐resistant superabsorbent composite

A novel semi‐interpenetrating polymer networks (semi‐IPNs) porous salt‐resistant superabsorbent composite was prepared by copolymerization of partially neutralized acrylic acid and acrylamide using polyethylene glycol as semi‐IPNs composite, N,N′‐methylenebisacrylamide, triene propanol phosphate, and trihydroxymethyl propane glycidol ether as crosslinking agents, methanol, propanol, and butanol as foaming agents, and L ‐ascorbic acid and peroxide hydrogen as initiators. To improve the properties of swollen hydrogel, such as strength, resilience, permeabilities, and dispersion, the copolymer was surface‐crosslinked, and then blended with aluminum sulfate, sodium carbonate, and sodium 1‐octadecanol phosphate in the course of post treatment. The influences of reaction conditions on properties of superabsorbent composite were investigated and optimized, and the water absorbency of superabsorbent composite prepared at optimal conditions in 0.9 wt% NaCl aqueous solution under atmospheric pressure and certain load (P ≈ 2 × 10³ Pa) were 61 g g^?1 and 16.7 g g^?1, respectively. Moreover, the swelling rate reached 22.003 × 10^?3 g (g s)^?1. And the excellent hydrogel properties, such as hydrogel strength, resilience, permeabilities, and dispersion were also obtained. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Improvement in physical and electrical properties of poly(vinyl alcohol) hydrogel conductive polymer composites

With an aim to develop anti‐electrostatic discharge materials based on biodegradable polymers, poly(vinyl alcohol) films composited with two different conductive fillers (carbon black and aluminium) at various fillers contents (20?60%wt), were manufactured using solvent‐casting technique. The mechanical properties of such the films were investigated through tensile stress‐strain tests. Wettability and morphology of the composite films were performed by water contact angle measurement and SEM, respectively. Young's modulus of the composite films can be increased with the addition of conductive fillers. The surface of the composite films showed non‐homogeneous appearance, in which the phase boundary within the composites was clearly observed and the conductive fillers formed aggregation structure at high filler concentration. In addition, the composite films exhibited better hydrophobicity when higher conductive filler content was added. TGA results suggested that both carbon black and aluminum have proven their efficiency to enhance thermal stability of poly(vinyl alcohol). Investigation of cross‐cut adhesion performance of the prepared composite films revealed that carbon black‐filled composites exhibited excellent adhesion strength. The effect of conductive filler content on surface resistivity of the composite films was also examined. The experimental results confirmed that both the fillers used in this study can improve the electrical conductivity of poly(vinyl alcohol) hydrogel. The surface resistivity of the composite films was reduced by several orders of magnitude when the filler of its critical concentration was applied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42234.     

Tri‐(butanediol‐monobutyrate) citrate plasticizing poly(lactic acid): Synthesis,crystallization, thermal,and mechanical properties

Tri‐(butanediol‐monobutyrate) citrate (TBBC) as a new plasticizer for poly(lactic acid) (PLA) was synthesized via a two‐step esterification. The chemical structure of TBBC was characterized by ¹H‐nuclear magnetic resonance. The studies on solubility parameters, transparence, and storage stability indicated the good miscibility between PLA and TBBC. The glass transition, crystallization, thermal, and mechanical properties of PLA plasticized by TBBC were evaluated. With an increase in TBBC content, the glass transition temperature (T_g), melting point (T_m), and the cold crystallization temperature (T_cc) of plasticized PLA gradually shifted to a lower temperature. The elongation at break and flexibility were greatly improved by the addition of TBBC. After 30 days of storage, PLA plasticized with up to 20 wt% of TBBC exhibited good storage stability and remained the original transparence and mechanical properties. The flexibility of PLA/TBBC films can be tuned by changing TBBC content. The corresponding crystalline morphology and structure were investigated by Polarizing optical microscope and X‐ray diffraction as well. This study revealed that TBBC was miscible with PLA and may therefore be a promising plasticizer for PLA‐based packaging materials. POLYM. ENG. SCI., 55:205–213, 2015. © 2014 Society of Plastics Engineers     

Dynamic mechanical properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) with aromatic hydrocarbon resin

The damping properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) (SIS) and hydrogenated aromatic hydrocarbon (C₉) resin were investigated by dynamic mechanical analysis. SIS exhibited two independent peaks of loss factor (tan δ) corresponding to the glass transition of polyisoprene (PI) and polystyrene (PS) segments, respectively. The addition of hydrogenated C₉ resin had a positive impact on the damping of SIS. With the increasing softening point and content of the resin, the main tan δ peak shifted to higher temperatures and the useful damping temperature range was broadened. Addition of mica or PS was found to widen the effective damping range evidently in the high‐temperature region, especially when PS was mixed in the solid state. It was concluded that the dispersed PS domains played a role of reinforcing fillers at low temperatures and served as a polymer component with a tan δ peak due to its glass transition at the high temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4157–4164, 2006     

Application of azodiisobutyronitrile and azobisisoheptonitrile in low‐density unsaturated polyester resin manufacturing

Low‐density unsaturated polyester resin (LDUPR) is an extended application of unsaturated polyester resin (UPR) material. In this study, azodiisobutyronitrile (AIBN) and azobisisoheptonitrile (ABVN) were presented as composite foaming agents and as initiators in LDUPR manufacturing. On the basis of the kinetics of AIBN and ABVN, their optimum half‐lives (t_1/2's) for LDUPR were both 1.0 h. In this study, the mass ratio of AIBN and ABVN was chosen at 7:3, and the preferred amount of the composite foaming agent was 2 wt % resin. They were treated at a molding temperature of 78.7 ± 1.0°C. The obtained LDUPR had an apparent density of 0.37 ± 0.01 g/cm³ and a specific compression strength of 35.58 ± 1.50 MPa·g^?1·cm^?3; it approached the highest specific compression strength value of rigid polyurethane foam (28–35 MPa g^?1 cm^?3). A dual‐initiation and dual‐foaming mechanism based on the dual‐exothermic decomposition properties of the composite foaming agent was proposed with the support of the differential scanning calorimetry and scanning electron microscopy results. In the first stage, ABVN decomposed, released bubble nuclei, and initiated UPR cross‐polymerization. The bubble nuclei spread in the resin glue and grew. In the second stage, the gas in resin glue was enriched by the AIBN decomposition. The gelation time of the resin glue was influenced by AIBN and delayed. With the curing of resin, more bubbles grew up, took shape, and were retained in the UPR matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40238.     

A parametric study on the processing parameters and properties of a porous poly(DL‐lactide‐co‐glycolide) acid 85/15 bioscaffolds

This study presents a comprehensive parametric study on the effects of processing parameters on the poly(DL‐lactide‐co‐glycolide) acid (PLGA) 85/15 scaffold's physical properties. Porous PLGA 85/15 scaffolds were prepared using a gas foaming/salt leaching technique. The processing parameters under examination for the gas foaming/salt leaching method included: gas saturation pressure (SP), gas saturation time, and NaCl/polymer mass ratio (NaCl/PMR). The physical properties considered in this study were the scaffold density, the scaffold porosity, and the average pore size of the scaffold. Young's moduli in compression, as well as the pore density (PD) inside the scaffold, were also studied. The results demonstrated optimum correlations of processing parameters are required to produce a scaffold with a high level of interconnectivity. In general, all scaffolds yielded by this experiment exhibited a porosity more than 90%, a relative density ranging from 0.0534 to 0.149 g/cm³, a PD ranging from 1.51 × 10⁶ to 6.72 × 10⁶ pores/cm³, and a compressive modulus ranging from 0.07 to 0.84 MPa. It was determined that the NaCl/PMR was the parameter that had the most significant effect on the physical properties of the scaffold. The average pore size was affected slightly by the SP only, and it was observed that the pore size was equivalent to the size of the NaCl particles used to make the scaffold. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Solid‐state foaming of carbon fiber/polypropylene/nano‐CACO3 composite using supercritical CO2

In this work, nano‐CaCO₃ was used to improve the foamability of carbon fiber (CF)/polypropylene (PP) composite in solid‐state foaming using supercritical CO₂. The CF content was maintained at 15 wt% and four concentrations of nano‐CaCO₃ content, 1, 3, 5 and 8phr, were used. The surface of nano‐CaCO₃ was firstly treated by silane coupling agent. By the way, the properties of the nano‐composites with various nano‐CaCO₃ contents were analyzed by scanning electron microscope (SEM), differential scanning calorimeter (DSC), and torque rheometer. Before foaming, the gas absorption experiment was done using gravimetric method. Concerning on determination of the foaming conditions, it is found that 175°C and 60s were suitable as foaming temperature and time. Furthermore, we can also find that the foamed composites with 3phr nano‐CaCO₃ showed the smallest mean cell diameter and largest cell density compared with the other nano‐CaCO₃ contents under the given saturation condition. In addition, the mean cell diameter decreased while cell density increased as saturation pressure increased because of the higher gas solubility in the composites. When the saturation pressure was 25MPa, the mean cell diameter and cell density with 3phr nano‐CaCO₃ were 17μm and 2.20×10⁷cells/cm³, respectively. POLYM. COMPOS., 35:1723–1735, 2014. © 2013 Society of Plastics Engineers