Effects of silica on the morphology,structure, and properties of thermoplastic cassava starch/poly(vinyl alcohol) blends

Thermoplastic cassava starch (TPS)/poly(vinyl alcohol) (PVA)/silica (SiO₂) composites were prepared by a melt‐mixing method. The effects of the content and surface properties of SiO₂ on the processing, mechanical properties, thermal stability, morphology, and structure of the TPS/PVA/SiO₂ composites were investigated. With increasing SiO₂ content, the plasticizing times of the TPS/PVA/SiO₂ composites were shortened. After the SiO₂ surface was treated with a silane coupling agent (KH550), the plasticizing times of the TPS/PVA/SiO₂ composites decreased significantly. The tensile strength, elongation at break, and Young's modulus of the TPS/PVA/SiO₂ composites increased. The mechanical properties of the TPS/PVA/SiO₂ composites containing treated SiO₂ were higher than those with untreated SiO_2. The thermal decomposition temperatures of the TPS/PVA/SiO₂ composites were improved with the addition of SiO₂. The presence of inorganic fillers was beneficial to the improvement of the thermal stability of the polymers. The reaction between the treated SiO₂ and the starch molecules was beneficial to the formation of more stable structures. The treated SiO₂ indicated good interfacial adhesion and uniform dispersion in the matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44020.     

A novel method of hyperbranched poly(amide‐ester) modifying nano‐SiO2 and study of mechanical properties of PVC/nano‐SiO2 composites

A new method of surface chemical modification of nano‐SiO₂ was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano‐SiO₂ reacted with AB₂‐type monomer (N,N‐dihydroxyethyl‐3‐amino methyl propionate) by one‐step polycondensation. And the product's Fourier transform infrared graphs and transmission electron microscopy (TEM) images proved that hyperbranched poly(amine‐ester) (HPAE) was grafted from nano‐SiO₂ surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano‐SiO₂ composites were made by melt‐blending. The composites' structures and mechanical properties were characterized by TEM, scanning electron microscopy, and electronic universal testing machine. The results showed that nano‐SiO₂ grafted by HPAE increased obviously in dispersion in PVC matrix, and mechanical properties of PVC were effectively improved. Additionally, it was found that mechanical properties of PVC/nano‐SiO₂ composites reached the best when weight percent of nano‐SiO₂ in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano‐SiO₂/PVC composite increased by 24.68% and its break elongation, flexural strength, and impact strength increased by 15.73, 4.07, and 184.84%, respectively. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Study of surface‐functionalized nano‐SiO2/polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO₂/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano‐SiO₂ particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO₂‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO₂‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO₂. At the same load of nano‐SiO₂, the nano‐SiO₂‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO₂/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO₂ content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO₂. The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

二氧化硅粒子对热塑性木薯淀粉稳定性能的影响

通过添加二氧化硅(SiO2)到木薯淀粉(TPS)中,采用熔融共混法制备热塑性TPS/SiO2复合材料,研究复合材料的吸水性、生物降解性和熔融行为。结果表明,随着SiO2添加量的增加,TPS吸水率呈下降趋势,且添加经过硅烷偶联剂(KH550)表面处理后的纳米SiO2比未处理的吸水率低。随着生物降解时间的增加,TPS/SiO2复合材料的生物降解率提高;随着SiO2用量的增加,TPS的生物降解率呈下降变化,且SiO2表面处理后能明显提高TPS的生物降解性。随着SiO2用量的增加,TPS的熔融峰增加,且添加SiO2表面处理后的TPS熔融峰比未经表面处理的SiO2高。     

Effect of the mixing sequence on the morphology and properties of a polypropylene/polydimethylsiloxane/nano‐SiO2 ternary composite

Ternary composites of polypropylene (PP), polydimethylsiloxane (PDMS) elastomer, and nano‐SiO₂, prepared with three different mixing sequences, were studied for dispersion morphology and its effect on the crystallization of PP and the mechanical properties. The mixing sequence produced a significant effect on the dispersion morphology and, thereby, on the mechanical properties of the composites. A two‐step mixing sequence, in which nano‐SiO₂ was added in the second step to the PP/PDMS binary system, produced a significant encapsulation of nano‐SiO₂ by PDMS, and this, in turn, resulted in the poor modulus and impact strength of the composite. A one‐step mixing sequence of all three components produced a separated dispersion of PDMS and nano‐SiO₂ phases in the PP matrix with the occurrence of a fine band of nano‐SiO₂ particles at the boundaries of the PDMS domains and the presence of some nano‐SiO₂ filler particles inside the PDMS domains. This one‐step mixing sequence produced an improvement in the tensile modulus but a decrease in the impact strength with increasing nano‐SiO₂ content. In the third sequence of mixing, which involved a two‐step mixing sequence through the addition of PDMS in the second step to the previously prepared PP/nano‐SiO₂ binary system, the morphology of the dispersion showed separately dispersed PDMS and nano‐SiO₂ phases with a loose network of nano‐SiO₂ particles surrounding the PDMS domains. This latter series of ternary composites had the highest impact strength and exhibited high shear deformation under tensile and impact conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A starch‐based biodegradable film modified by nano silicon dioxide

The purpose of this work was to improve the properties of the starch/poly(vinyl alcohol) (PVA) films with nano silicon dioxide (nano SiO₂). Starch/PVA/nano‐SiO₂ biodegradable blend films were prepared by a solution casting method. The characteristics of the films were assessed by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The results obtained in this study indicated that the nano‐SiO₂ particles were dispersed evenly within the starch/PVA coating and an intermolecular hydrogen bond and a strong chemical bond C? O? Si were formed in the nano‐SiO₂ and starch/PVA. That the blending of starch, PVA and nano‐SiO₂ particles led to uniform starch/PVA/nano‐SiO₂ blend films with better mechanical properties. In addition, the nano‐SiO₂ particles can improve the water resistance and light transmission of the blend films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology and properties of PET/PA‐6/SiO2 ternary composites

A kind of hydrophilic nano‐SiO₂ was applied to poly(ethylene terephthalate)/polyamide‐6 (PA‐6) blends. Melt‐blended composites were prepared at various component ratios and different nano‐SiO₂ levels. Mechanical, morphological, dynamic mechanical, and thermal tests were carried out to characterize the properties, morphology, and compatibilization of the composites. Increased impact strength, tensile strength, and modulus were observed by adding nano‐SiO₂ particles in the blends. The nano‐SiO₂ particles were found to be preferentially dispersed in PA‐6, resulting in an increase of glass transition temperature and crystallization of PA‐6. The mechanism of morphology and properties changes was discussed based on the selective dispersion of nano‐SiO₂ particles in the blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2288–2296, 2007     

Noticeable viscosity reduction of polycarbonate melts caused jointly by nano‐silica filling and TLCP fibrillation

Nano‐SiO₂ was introduced into in‐situ composites of polycarbonate (PC) and a thermotropic liquid crystalline polymer (TLCP) using a twin‐screw extruder. The rheology of these composites was characterized with capillary rheometry, and the morphology of the dispersed TLCP observed with scanning electron microscopy. The rheological data revealed that the viscosity decrease of PC melts by only the addition up to 20 wt% TLCP remained smaller than 30%, while it became ～48% upon further addition of only about 1 wt% nano‐SiO₂ and larger than 60% upon ～9 wt% nano‐SiO₂ filling, in contrast to a 50% viscosity increase of PC melts with increase in nanosilica loading up to ～9 wt%. These silica‐filled composites exhibited markedly low viscosity, especially at relatively high shear rates. The morphology of TLCP extracted from unfilled and silica‐filled composites indicated that the largest viscosity reduction was correlated well with the fibrillation of TLCP droplets enhanced by nano‐SiO₂. The TLCP/SiO₂/PC composites exhibited rheological hybrid effect with fillers at nanometer scale. POLYM. ENG. SCI., 47:757–764, 2007. © 2007 Society of Plastics Engineers     

纤维增强尿素和甲酰胺混合塑化热塑性淀粉

使用尿素和甲酰胺混合塑化剂制备的热塑性淀粉(UFPTPS)可以有效抑制淀粉的回生。用这种热塑性淀粉作为短棉绒纤维的基质,制备的纤维增强热塑性淀粉(FRTPS)可以提高其力学性能和耐水性能。扫描电镜显示了短棉绒纤维较好地分散在UFPTPS中,纤维和淀粉结合良好。X ray衍射说明加入纤维后作为基质的UFPTPS仍可以抑制淀粉回生。纤维质量分数对FRTPS力学性能影响的研究显示,随着w(纤维)=0%提高到20%,FRTPS拉伸强度翻番达到10 16MPa,杨氏模量达到97 85N/mm2;伸长率从105%降到17%,断裂能从2 158N·m降到0 573N·m。随着水质量分数的增加,增强效应逐渐被弱化,在高水含量[w(水)>30%]时,水分和纤维质量分数对强度没有影响。FRTPS与UFPTPS相比,耐水性明显提高。     

Preparation and performance of nano‐SiO2 stabilized Pickering emulsion type sizing agent for glass fiber

The nano‐SiO₂ particles modified by silane coupling agent A‐1100 were used for preparing the vinyl ester resin (VE) Pickering emulsion. The stable emulsion could be served as the film former of sizing agent for glass fiber (GF). The influence of the wettability and the addition amount of nano‐SiO₂ on the stability of film former emulsion was explored. The effect of nano‐SiO₂ Pickering emulsion type sizing agent on the properties of GF was investigated. SEM images show that there existed a layer of sizing agent film with nano‐SiO₂ particles evenly on the GF surface. The abrasion resistance of the sized GF reached 3,579 times and the stiffness was 69 mm. The strand integrity also performed well. The fracture strength of GF bundles treated by Pickering emulsion type sizing agent increased by 28.6% to 0.504 N/Tex compared with that of the unsized GF bundles. The interlaminar shear strength (ILSS) of GF/VE composites sized by self‐made sizing agent which contained nano‐SiO₂ has improved, compared to the unsized GF reinforced VE composite. POLYM. COMPOS., 37:334–341, 2016. © 2014 Society of Plastics Engineers     

Soy protein plastics reinforced and toughened by SiO2 nanoparticles

The nano‐SiO₂ particles were compounded into soy protein isolated (SPI) matrix to produce a series of reinforcing nanocomposite sheets by compression‐molding. Except for the expected increase of strength and modulus, the elongation was also enhanced when the nano‐SiO₂ content was lower than 8 wt %. Moreover, two nanocomposite materials were recommended: the one is a nanocomposite containing 4 wt % nano‐SiO₂ with the highest strength and enhanced elongation, the other is a reinforced material with the best elongation filled by 8 wt % nano‐SiO₂. The increase of nano‐SiO₂ content produced many kinds of distributions in SPI matrix, such as single nanosphere, ～ 100 nm nanocluster, interconnected network structure and great domain. Such structures strongly affected the mechanical performances of nanocomposite materials. The simultaneous enhancement of strength and elongation was related to homogeneous dispersion of nanoclusters while aggregated great domains severely decreased elongation in spite of obvious reinforcing effect. However, the reinforced materials with high loading of inorganic filler should be paid attention and have economic value to some extent in practical application. With the changes of nano‐SiO₂ distribution, the structures of SPI matrix changed as well. After adding a mall amount of nano‐SiO₂, the damage of glycerol plasticization to ordered structure of SPI was reduced. But as nano‐SiO₂ content increased, the SPI microphase was separated from nano‐SiO₂ domains. Furthermore, the condition of simultaneous reinforcing and toughening was put forward: the moderate aggregation of nano‐SiO₂ as well as all kinds of strong interfacial interactions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of high nano‐SiO2 contents on properties of epoxy‐modified polybenzoxazine

High‐performance nanosilica composites based on epoxy‐modified polybenzoxazine matrices are developed. Chemorheological study of benzoxazine–epoxy resin mixtures reveals that processing window of the benzoxazine resin (BA‐a) is substantially broadened with an addition of the liquid epoxy. Glass transition temperature (T _g) of the BA‐a copolymerized with epoxy resin shows a synergistic behavior with a maximum T _g value (174°C) at the benzoxazine–epoxy mass ratio of 80:20. The copolymer at this composition is also used as a matrix for nano‐SiO₂ composites. A very low melt viscosity of the benzoxazine–epoxy mixtures promotes good processability with the maximum attainable nano‐SiO₂ loading up to 35 wt%. From scanning electron microscopy investigation, fracture surface of the 35 wt% nano‐SiO₂‐filled benzoxazine–epoxy composite reveals relatively homogeneous distribution of the nano‐SiO₂ in the copolymer with good particle wet‐out. In addition, very high reinforcing effect was also observed in such high content of the nano‐SiO₂, i.e., about 2.5 times in modulus improvement. This improvement is attributed to the strong bonding between the copolymer matrix and the nano‐SiO₂ through ether linkage as confirmed by Fourier‐transform infrared investigation. POLYM. COMPOS., 38:2261–2271, 2017. © 2015 Society of Plastics Engineers     

Effect of nano‐SiO2 on granule characteristic and fusion process of Poly(vinyl chloride‐co‐vinyl acetate)/nano‐SiO2 composite resin

Poly(vinyl chloride‐co‐vinyl acetate) (PVVA)/nano‐SiO₂ composite resin was prepared by radical suspension polymerization of the monomers in the presence of fumed nano‐SiO₂ particles premodified with γ‐methylacryloxypropyl trimethoxysilane. The cool dioctyl phthalate absorption percentage, granule porosity, and specific surface area of the composite resin were enhanced through incorporation of nano‐SiO₂ into the PVVA. Scanning electron microscope pictures showed the resin had higher porosity. PVVA/nano‐SiO₂ composite resin was mixed with pure PVC resin to form a mixture sample (polymer‐composite blend [PCB]) and the mixture was fused in the torque rheometer. The rheological test results indicated that, at a certain nano‐SiO₂ content, the fusion speed of PCB was accelerated and the fusion temperature of PCB was decreased, owing to nano‐SiO₂ dispersed evenly in the polymer matrix. When excessive nano‐SiO₂ was loaded, the fusion torque, the fusion time, and the fusion temperature of PCB were all increased. These properties are correlative to the dispersive density of nano‐SiO₂ in the polymer matrix. This study also demonstrated that the introduction of small amounts of nano‐SiO₂ into the resin increased the impact strength and tensile strength of PCB simultaneously. J. VINYL ADDIT. TECHNOL., 20:230–236, 2014. © 2014 Society of Plastics Engineers     

Preparation of styrene‐acrylic emulsion by using nano‐SiO2 as seeds

A styrene‐acrylic/SiO₂ nanoparticle composite emulsion was prepared by using SiO₂ nanoparticles as seeds. The effect of factors such as the level of nano‐SiO₂, reaction temperature and ultrasound treatment of nano‐SiO₂ on the stability of the polymerization reaction was investigated. Water‐resistance of the emulsion was measured. The level of nano‐SiO₂ in the emulsion was determined by inductively coupled plasma (ICP) spectrometry. The particle morphology of the emulsion with nano‐SiO₂ was observed with transmission electron microscopy (TEM). The kinetics of the polymerization was also studied at various temperatures and various levels of nano‐SiO₂. They showed that the level of nano‐SiO₂ and reaction temperature had a great influence on the monomer conversion, particle size, coagulum content and viscosity of the emulsion. Nano‐SiO₂ treated by ultrasonics can increase the coagulum content greatly, but it does not improve the water resistance of the emulsion. The level of nano‐SiO₂ in the emulsion was lower than the theoretical value. The reaction kinetics indicated that the level of nano‐SiO₂ had less influence on the reaction rate than the reaction temperature. Even a small amount of nano‐SiO₂ can decrease the reaction rate. Copyright © 2004 Society of Chemical Industry     

Effect of nano‐silica on the mechanical,thermal, and crystalline properties of poly(vinyl alcohol)/nano‐silica films

Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO₂) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO₂ films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO₂ were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO₂ and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO₂ decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO₂ content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO₂ loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of nanosilica on the thermal,mechanical, and dielectric properties of polyarylene ether nitriles terminated with phthalonitrile

Nanosilica/polyarylene ether nitriles terminated with phthalonitrile (SiO₂/PEN‐t‐Ph) composites were prepared by hot‐press approach. To ensure the nano‐SiO₂ can disperse uniformly, the solution casting method combined with ultrasonic dispersion technology had been taken previously. The mass fraction of nano‐SiO₂ particles was varied to investigate their effect on the thermal, mechanical, and dielectric properties of the nanocomposites. From scanning electron microscope images, it was found that the nanoSiO₂ particles were dispersed uniformly in the PEN‐t‐Ph matrix when the addition of nano‐SiO₂ was less than 16.0 wt%. However, when the mass fraction of nano‐SiO₂ increased to 20.0 wt%, the nano‐SiO₂ particles tend to self‐aggregate and form microns sized particles. Thermal studies revealed that nano‐SiO₂ particles did not weaken the thermal stabilities of the PEN‐t‐Ph matrix. Mechanical investigation manifested that the SiO₂/PEN‐t‐Ph nanocomposites with 12.0 wt% nano‐SiO₂ loading showed the best mechanical performance with tensile strength of 108.2 MPa and tensile modulus of 2107.5 Mpa, increasing by 14% and 19%, respectively as compared with the pure PEN‐t‐Ph film. Dielectric measurement showed that the dielectric constant increased from 3.70 to 4.15 when the nano‐SiO₂ particles varied from 0.0 to 20.0 wt% at 1 kHz. Therefore, such composite was a good candidate for high performance materials at elevated temperature environment. POLYM. COMPOS., 35:344–350, 2014. © 2013 Society of Plastics Engineers     

Investigation on the mechanical performances of ternary nylon 6/SEBS elastomer/nano‐SiO2 hybrid composites with controlled morphology

The distribution of maleated styrene‐hydrogenated butadiene‐styrene (mSEBS) elastomer and nano‐SiO₂ in nylon 6 matrix was controlled by varying the blending procedure. Nano‐SiO₂ particles with different surface properties (hydrophilic versus hydrophobic) were adopted to adjust their interactions with other components. Two different structures, separate dispersion of nano‐SiO₂ and elastomer particles as well as encapsulation of nano‐SiO₂ fillers by the elastomer, were obtained. The structures were confirmed through scanning electron microscope (SEM) investigation. The mechanical measurement results showed that the microstructure and the interactions among the components had dramatic influences on the final mechanical properties, especially Izod fracture toughness, for the ternary nanocomposites. The nanocomposites containing hydrophilic nano‐SiO₂ had better mechanical performances compared with the composites filled with hydrophobic SiO₂ when they were in the same microstructure. The nanocomposites with separate dispersion structure showed higher stiffness compared with those of encapsulation type. However, the separately dispersed nano‐SiO₂ particles restricted the cavitation of elastomer phases that led to low toughening effectiveness. The difference of cavitation intensity for elastomer phase was revealed by SEM investigation on the facture surfaces for the nanocomposites with the two different microstructures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical properties of low nano‐silica filled high density polyethylene composites

Modification of nanoparticles through graft polymerization is able to change the chemical nature of the particles' surfaces and provides an effective means for the preparation of nano‐fillers specified for composites manufacturing. The present work focuses on the mechanical role of grafted nano‐SiO₂ particles in high density polyethylene composites prepared by melt compounding. The experimental results show that at a content of 0.75 vol%, the modified nano‐silica results in a rise in tensile stiffness, tensile strength and impact strength of the composites. The grafted nanoparticles can improve the mechanical performance of the matrix polymer more effectively than the untreated version. In addition, a further enhancement of the composites stiffness and strength can be achieved by crosslinking the concentrated masterbatches, which has not yet been revealed in the authors' previous works on grafted nano‐SiO₂ particles/polypropylene composites. It is thus revealed that the introduction of the grafting polymers onto the nanoparticles increases the tailorability of the composites.     

Effect of in situ surface‐modified nano‐SiO2 on the thermal and mechanical properties and crystallization behavior of nylon 1010

Nylon 1010 composites filled with two types of surface‐modified SiO₂ nanoparticles (RNS and DNS) were prepared by melt blending. The mechanical properties of the composites were evaluated. The influences of the surface‐modified nano‐SiO₂ on the thermal stability, crystallization behavior, and microstructure of nylon 1010 were investigated by thermogravimetric analysis, differential scanning calorimetry (DSC), X‐ray diffraction, and transmission electron microscopy. And the interfacial interactions between the fillers and polymer matrix were examined using a Fourier transformation infrared spectrometer. It was found that the addition of the surface‐modified nano‐SiO₂ had distinct influences on the thermal stability, mechanical properties, and crystallization behavior of nylon 1010. RNS and DNS as the fillers had different effects on the mechanical properties of nylon 1010. The composites filled with RNS at a mass fraction of 1–5% showed increased break elongation, Young's modulus, and impact strength but almost unchanged or even slightly lowered tensile strength than the unfilled matrix. The DNS‐filled nylon 1010 composites had obviously decreased tensile strength, whereas the incorporation of DNS also contributed to the increase in the Young's modulus of nylon 1010, but less effective than RNS. Moreover, the nylon 1010 composites had better thermal stability than the neat polymer matrix, and the composites filled with RNS were more thermally stable than those filled with DNS. The difference in the crystallinity of neat nylon 1010 and its composites filled with RNS and DNS was subtle, although the surface‐modified nano‐SiO₂ could induce or/and stabilize the γ‐crystalline formation of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The influence of interphase on nylon‐6/nano‐SiO2 composite materials obtained from in situ polymerization

Three commercially available silane, titanate and aluminate based coupling agents were used to pretreat nano‐SiO₂ for the preparation of nylon‐6/nano–SiO₂ composites via in situ polymerization. The interphases formed in different composite systems and their influence on material properties were investigated. Results indicated that the interfacial interactions differed between composite systems, whereas rigidity and toughness of composites were all improved by addition of pretreated silicas at an optimal content of 4.3 wt%. The presence of pretreated silicas did not have a distinct influence in the non‐isothermal crystallization behaviour of the nylon matrix. The composites containing pretreated silicas had slightly higher dynamic viscosities and superior storage moduli at high frequency, compared with neat nylon‐6. Copyright © 2003 Society of Chemical Industry