英语翻译the average length of the dispersed clay particles,andhe

英语翻译the average length of the dispersed clay particles,andhence the aspect ratio.Fig.81 represents thedependence of the tensile modulus E measured at120 8C for exfoliated N6 nanocomposites with variousclay content,obtained by the in situ intercalativepolymerization of 1-caprolactam in the presence ofprotonated aminododecanoic acid-modified MMTand saponite.Moreover,the difference in the extentof exfoliation,as observed for N6-based nanocompositessynthesized by the in situ intercalative polymerizationof 1-caprolactam using Naþ-MMT andvarious acids,strongly influenced the final modulusof the nanocomposites.Table 14 summarizes the tensile modulus of1potNCH together with neat N6 and NCH preparedvia in situ intercalative ring-opening polymerizationof 1-caprolactam [135].The excellent modulus in thecase of 1potNCH is attributed to the uniformlydispersed silicate layers.Furthermore,1potNCH hasimproved mechanical properties when compared withNCH.The polymer matrix in the nanocompositesprepared by a one pot synthesis is the homopolymer ofN6,whereas in the case of NCH prepared viaintercalative ring-opening polymerization,the matrixis a copolymer of N6 and a small amount of N12.Thepresence of N12 may give rise to the lower modulus.One can observe variations of the modulus of thenanocomposites based on the various kinds ofacids used to catalyze the polymerization [135].The WAXD peak intensity (Im; inversely related tothe exfoliation of clay particles) also depends on thenature of the acid used to catalyze the polymerizationprocess.For an increase in the Im values,a paralleldecrease in the modulus is observed,indicating thatexfoliated layers are the main factor responsible forthe stiffness improvement.Intercalated particles,having a less important aspect ratio,play a minorrole.These observations are further confirmed inFig.82,which presents the evolution of the tensilemodulus at room temperature of N6 nanocompositesobtained by melt extrusion as a function of the fillercontent [142]