Mechanical and tribological behaviors of polyamide 66/ultra high molecular weight polyethylene blends

The blends of polyamide (PA) and ultra high molecular weight polyethylene (UHMWPE) were prepared by a Brabender DSE25 co‐twin screw extruder, and maleic anhydride (MAH) grafted high‐density polyethylene (HDPE) was used as a compatibilizer. A chemical reaction between MAH group of MAH‐g‐HDPE and terminal amino group of PA was testified by FT‐IR analysis. Mechanical and tribological tests showed that the tensile and bending strength of PA decrease with the increase of UHMWPE. Besides, the mechanical strengths of PA/UHMWPE blends were improved by adding appropriate MAH‐g‐HDPE. The chemical reaction between MAH‐g‐HDPE and PA ameliorated the homogeneous dispersing ability of UHMWPE in the blend. The friction coefficient and volume wear rate of the PA/UHMWPE blends decreased apparently with the increase of UHMWPE, as was probably that UHMWPE has straight chain structure and good flexibility; therefore, a transferring film could be easily formed on the steel surface with the increase of UHMWPE. In friction process, the wear resistance of the blends was relative to the mechanical property of the blends when the amount of the transferring layer reached to a certain value. POLYM. ENG. SCI., 47:738–744, 2007. © 2007 Society of Plastics Engineers.     

Morphology,thermal behavior,and mechanical properties of PA6/UHMWPE blends with HDPE‐g‐MAH as a compatibilizing agent

A functionalized high‐density polyethylene (HDPE) with maleic anhydride (MAH) was prepared using a reactive extruding method. This copolymer was used as a compatibilizer of blends of polyamide 6 (PA6) and ultrahigh molecular weight polyethylene (UHMWPE). Morphologies were examined by a scanning electron microscope. It was found that the dimension of UHMWPE and HDPE domains in the PA6 matrix decreased dramatically, compared with that of the uncompatibilized blending system. The size of the UHMWPE domains was reduced from 35 μm (PA6/UHMWPE, 80/20) to less than 4 μm (PA6/UHMWPE/HDPE‐g‐MAH, 80/20/20). The tensile strength and Izod impact strength of PA6/UHMWPE/HDPE‐g‐MAH (80/20/20) were 1.5 and 1.6 times as high as those of PA6/UHMWPE (80/20), respectively. This behavior could be attributed to chemical reactions between the anhydride groups of HDPE‐g‐MAH and the terminal amino groups of PA6 in PA6/UHMWPE/HDPE‐g‐MAH blends. Thermal analysis was performed to confirm that the above chemical reactions took place during the blending process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 232–238, 2000     

Compatibilization of immiscible nylon 6/poly(vinylidene fluoride) blends using graphene oxides

A new strategy to compatibilize immiscible blends is proposed, using graphene oxide (GO) nanosheets taking advantage of their unique amphiphilic structures. When 0.5 or 1 wt% GOs were incorporated in immiscible nylon 6/poly(vinylidene fluoride) (PVDF) (90/10 wt%) blends, the dimension of PVDF dispersed particles was markedly reduced and became more uniform, revealing a well‐defined compatibilization effect of GOs on the immiscible blends. Correspondingly, the ductility of the compatibilized blends increased several times compared with uncompatibilized immiscible blends. In order to explore the underlying compatibilization mechanism, Fourier transform infrared and Raman spectra were applied to suggest that the edge polar groups of GOs can form hydrogen bonds with nylon 6 while the basal plane of GOs can interact with electron‐withdrawing fluorine on PVDF chains leading to the so‐called charge‐transfer C–F bonding. In this case, GOs exhibit favorable interactions with both nylon 6 and PVDF phase, therefore stabilizing the interface during GO migrations from PVDF/GO masterbatch to nylon 6 phase, which can minimize the interfacial tension and finally lead to compatibilization effects. Obviously, this work may open a broad prospect for GOs to be widely applied as a new compatibilizer in industrial fields. © 2012 Society of Chemical Industry     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The role of polycarbonate molecular weight in the poly(L‐lactide) blends compatibilized with poly(butylene succinate‐co‐L‐lactate)

Poly(butylene succinate‐co‐L ‐lactate) (PBSL)–compatibilized poly(L ‐lactide) (PLLA) polymer blends with two commercial grades of polycarbonate (PC) were investigated. The capillary tests showed that the steady shear viscosity of high molecular weight PC (PC‐L) was 10 times higher than that of low molecular weight PC (PC‐AD) throughout the shear rate range under investigation. Morphologic examination revealed that the shape of the dispersed PC‐L phase in the as‐extruded blends was largely spherical, but the PC‐AD phase was more like a rod and elongated further during injection molding. Notched Izod impact strength (IS) of the unmodified PLLA/PC‐L blend was higher than that of PC‐AD blend. The IS of modified ternary blends increased with PBSL content because of enhanced phase interaction indicated from thermal and morphologic analysis. The PBSL modification also enhanced IS more significantly in PLLA/PC‐L than in PLLA/PC‐AD blends. On the contrary, the heat deflection temperature (HDT) of PLLA/PC‐L binary system was much lower than that of PLLA/PC‐AD. HDT of PBSL‐modified PLLA/PC‐AD blends dropped with increasing PBSL content, which is a ductile polymer. Thermal and dynamic mechanical analysis of the ternary blends showed that individual components were immiscible with distinct T_gs for PC and PLLA and distinct T_ms for PBSL and PLLA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Drawing in high pressure CO2—a new route to high performance fibers in memory of late Roger Porter

In this paper, we introduce a new draw technique for polymer orientation and apply it to different polymer fibers: poly(ethylene terephthalate) or PET, nylon 6,6, and ultra‐high molecular polyethylene (UHMWPE). In this technique, a polymer is drawn uniaxially in supercritical CO₂ using a custom high‐pressure apparatus. This technique can be used in replacement of a traditional drawing process or as a post‐treatment process. With PET, the technique is not effective at temperatures at or below 130°. In contrast, the process is highly effective for nylon 6,6 where CO₂ drawn fibers show significantly higher crystallinity and orientation along with improved mechanical properties. While the fibers are plasticized, the drawability of the fibers is only slightly dependent on temperature. High pressure CO₂ drawing of ultrahigh molecular weight polyethylene (UHMWPE) fibers is equally effective. Commercial high performance fibers can be drawn up to a ratio of 1.9 in asecond stage, resulting in large increases in tensile modulus and small improvements in tensile strength.     

Irradiation grafting of methyl methacrylate monomer onto ultra‐high‐molecular‐weight polyethylene: An experimental design approach for improving adhesion to bone cement

The grafting of methyl methacrylate (MMA) onto ultra‐high‐molecular‐weight polyethylene (UHMWPE) and chromic acid etched UHMWPE was conducted with a preirradiation method in air in the presence of a Mohr salt and sulfuric acid. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, a gravimetric method, differential scanning calorimetry, scanning electron microscopy (SEM), and interfacial bonding strength measurements. The FTIR results showed the presence of ether and carbonyl groups in the MMA‐grafted UHMWPE (MMA‐g‐UHMWPE) samples. The Taguchi experimental design method was used to find the best degree of grafting (DG) and bonding strength. The efficient levels for different variables were calculated with an analysis of variance of the results. SEM micrographs of MMA‐g‐UHMWPE samples showed that with increasing DG and chromic acid etching, the MMA‐g‐UHMWPE rich phase increased on the surface; this confirmed the high interfacial bonding strength of the grafted samples with bone cement. The grafting of the MMA units onto UHMWPE resulted in a lower crystallinity, and the crystallization process proceeded at a higher rate for the MMA‐g‐UHMWPE samples compared to the initial UHMWPE; this suggested that the MMA grafted units acted as nucleating agents for the crystallization of UHMWPE. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of entangled state of nascent UHMWPE on structural and mechanical properties of HDPE/UHMWPE blends

In this study, a synthesized ultra‐high molecular weight polyethylene (UHMWPE) with a less entangled state and a commercial UHMWPE with a highly entangled state were blended with high‐density polyethylene (HDPE) by melt blending, respectively. Rheology, 2D small‐angle X‐ray scattering (2D‐SAXS), differential scanning calorimetry (DSC), and tensile test were used to study the relationship between the microstructure and the mechanical properties of blends. It was demonstrated that the UHMWPE with the less entangled state was easy to be oriented at a given flow. More mechanical networks were achieved among the HDPE matrix and the UHMWPE chains due to the fewer entanglements of synthesized UHMWPE, improving the melting recovery of blends. Furthermore, notably oriented structures (shish‐kebabs) with increased long‐periods were made in the blends of weakly entangled UHMWPE and HDPE. The tensile strength of this blend was thus enhanced, i.e., the tensile strength raised for neat HDPE from 45.7 to 83.1 MPa for HDPE/UHMWPE blends containing 10 wt % of less entangled UHMWPE. However, the phase separation of blends was characterized when more weakly entangled UHMWPE was incorporated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44728.     

Toughening effects of ethylene–vinyl acetate copolymers with different vinyl acetate content and viscosity on nylon 1010 blends

Nylon 1010 blends with ethylene–vinyl acetate copolymer (EVA) and maleated ethylene–vinyl acetate (EVA‐g‐MAH) were prepared through melt blending. The vinyl acetate (VA) content and viscosity of EVA significantly affected the notched impact strength of nylon/EVA/EVA‐g‐MAH (80/15/5) blends. The nylon/EVA/EVA‐g‐MAH blends with high notched impact strength (over 60 kJ/m²) were obtained when the VA content in EVA ranged from 28 to 60 wt%. The effect of VA content on the notched impact strength of blends was related to the glass transition temperature for EVA with high VA content and crystallinity for EVA with low VA content. For nylon blends with EVA with the same VA content, low viscosity of EVA led to high notched impact strength. Fracture morphology of nylon/EVA/EVA‐g‐MAH (80/15/5) blends showed that blends with ductile fracture behavior usually had large matrix plastic deformation, which was the main energy dissipation mechanism. A relationship between the notched impact strength and the morphology of nylon/EVA/EVA‐g‐MAH (80/15/5) blends was well correlated by the interparticle distance model. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Morphology and properties of nylon 6 and high density polyethylene blends in presence of nanoclay and PE‐g‐MA

In this study, we report the synergistic effect of nanoclay and maleic anhydride grafted polyethylene (PE‐g‐MA) on the morphology and properties of (80/20 w/w) nylon 6/high density polyethylene (HDPE) blend. Polymer blend nanocomposites containing nanoclay with and without compatibilizer (PE‐g‐MA) were prepared by melt mixing, and their morphologies and structures were examined with scanning electron microscopy (SEM) and wide angle X‐ray diffractometer (WAXD) study. The size of phase‐separated domains decreased considerably with increasing content of nanoclay and PE‐g‐MA. WAXD study and transmission electron microscopy (TEM) revealed the presence of exfoliated clay platelets in nylon 6 matrix, as well as, at the interface of the (80/20 w/w) nylon 6/HDPE blend–clay nanocomposites. Addition of PE‐g‐MA in the blend–clay nanocomposites enhanced the exfoliation of clays in nylon 6 matrix and especially at the interface. Thus, exfoliated clay platelets in nylon 6 matrix effectively restricted the coalescence of dispersed HDPE domains while PE‐g‐MA improved the adhesion between the phases at the interface. The use of compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of compatibilizer precursor structure on the phase distribution of low density poly(ethylene) in a poly(ethylene terephthalate) matrix

In attempt to enhance the compatibility of PET/LDPE blends by using a proper functionalized polymer as third component, diethyl maleate (DEM)‐functionalized ultralow density poly(ethylene) (ULDPE‐g‐DEM) and styrene‐b‐(ethylene‐co‐1‐butene)‐b‐styrene triblock copolymer (SEBS‐g‐DEM) were prepared by radical functionalization in the melt. Immiscible PET/LDPE blends having compositions of 70/30 and 80/20 by weight were then extruded in the presence of 1–10% by weight of ULDPE‐g‐DEM and SEBS‐g‐DEM as compatibilizer precursors and ZnO (0.3% by weight) as transesterification catalyst. In both cases, evidences about the occurring of compatibilization between the two immiscible phases, thanks to the studied reactive processes, were obtained. Moreover, the phase distribution and particle size of blends were deeply investigated. Completely different kinds of phase morphology were achieved, as ULDPE‐g‐DEM stabilized a dispersed phase morphology, whereas SEBS‐g‐DEM favored the development of a cocontinuous phase morphology. The observed differences are tentatively explained onthe basis of reactivity and physical features of polymers. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Miscibility studies of binary and ternary mixtures of tactic poly(methyl methacrylates) with poly(vinylidene chloride‐co‐acrylonitrile)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (i, a, and s PMMAs) were mixed with poly(vinylidene chloride‐co‐acrylonitrile) (Saran F) separately in tetrahydrofuran to make three polymer blend systems. Differential scanning calorimetry (DSC) was used mainly to study the miscibility of these blends. iPMMA and aPMMA were found to be miscible with Saran F based on the transparency and a single glass transition temperature (T_g) of the films. However, sPMMA was immiscible with Saran F because of the observation of two T_gs and opacity in most compositions of the blend. aPMMA is known to be miscible with sPMMA. Therefore aPMMA is both miscible with Saran F and sPMMA but Saran F and sPMMA are immiscible. Preliminary results of the effect of adding of aPMMA to immiscible sPMMA and Saran F mixtures were also reported. First, binary mixtures of atactic and syndiotactic PMMAs were also prepared and confirmed to be miscible. Elevation of T_g of the aPMMA/sPMMA blend above weight average was observed probably due to stereocomplexation occurred between aPMMA and sPMMA. Then ternary blends of atactic and syndiotactic PMMAs and Saran F in the weight ratios of about 3/1/4, 2/2/4, and 1/3/4 were also measured calorimetrically. A single T_g was observed for these three compositions different from two T_gs detected in the sPMMA/Saran F (50.0/50.0, i.e., 4/4) blend. Obviously, the composition of Saran was fixed in the ternary blends. When the other half of the blends was changing from pure sPMMA to sPMMA and aPMMA mixture, the blends became miscible because of the addition of aPMMA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1313–1321, 2000     

Toughening and compatibilization of polyphenylene sulfide/nylon 66 blends with SEBS and maleic anhydride grafted SEBS triblock copolymers

In this study, styrene‐b‐ethylene/butylene‐b‐styrene triblock copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were used as compatibilizers for the blends of polyphenylene sulfide/nylon 66 (PPS/PA66). The mechanical properties, including impact and tensile properties and morphology of the blends, were investigated by mechanical properties measurements and scanning electron microscopy. Impact measurements indicated that the impact strength of the blends increases slowly with elastomer (SEBS and SEBS‐g‐MA) content upto 20 wt %; thereafter, it increases sharply with increasing elastomer content. The impact energy of the elastomer‐compatibilized PPS/PA66 blends exceeded that of pure nylon 66, implying that the nylon 66 can be further toughened by the incorporation of brittle PPS minor phase in the presence of SEBS or SEBS‐g‐MA. The compatibilization efficiency of SEBS‐g‐MA for nylon‐rich PPS/PA66 was found to be higher than SEBS due to the in situ forming SEBS interphase between PPS and nylon 66. The correlation between the impact property and morphology of the SEBS‐g‐MA compatibilized PPS/PA66 blends is discussed. The excellent impact strength of the nylon‐rich blends resulted from shield yielding of the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

SiO2-covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO2) nanocomposites with superior mechanical and tribological properties

The modified Hummer technique was used in the preparation of graphene oxide (GO) nanosheets, and then SiO₂ decorated GO [GO(SiO₂)] nanosheets were synthesized via the sol–gel method. Then, ultrahigh-molecular-weight polyethylene (UHMWPE) nanocomposites loaded with 0.5, 1, 1.5, and 2 wt % of GO(SiO₂) were prepared using magnesium ethoxide/GO(SiO₂)-supported Ziegler–Natta catalysts via the in situ polymerization. Morphological study of the prepared polymer powders was assessed using field-emission scanning electron microscopy, which showed that GO(SiO₂) nanohybrids have been uniformly dispersed and distributed into the UHMWPE matrix. Also, the neat UHMWPE and its nanocomposites were evaluated with different analyses, including viscosity-average molecular weight measurement, differential scanning calorimetry, thermogravimetric analysis, tensile test, scratch hardness, and pin-on-disk test. The characterization of the UHMWPE nanocomposites indicated that many characterizations, including the mechanical, thermal, and tribological properties of UHMWPE, were significantly improved by incorporation of these new nanosheets in spite of the molecular weight reduction of the polymeric matrix and the improved flowability and processability of the produced nanocomposite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47796.     

Studies on nonisothermal crystallization of ultra–high molecular weight polyethylene in liquid paraffin

The nonisothermal crystallization kinetics for ultra–high molecular weight polyethylene (UHMWPE) in liquid paraffin (LP) systems was investigated through differential scanning calorimetry (DSC) measurement. The influence of UHMWPE concentration and cooling rate on crystallization mechanism and spherulitc structure as implied by the modified Avrami equation and Mo's analysis was determined, whereas the Ozawa's approach fails to describe the crystallization behaviors of these UHMWPE‐diluent systems. As a result, in the modified Avrami analysis, it was found that the Avrami exponent is constant around five at various concentrations of UHMWPE and cooling rates. Further, the value of F(T) in the Mo's approach increases with the increasing of relative crystallinity and UHMWPE content in the blends. The nonisothermal crystallization kinetics presented here are the first for UHMWPE‐diluent systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Properties and morphologies of PVC/nylon terpolymer blends

A new kind of blends of polyvinyl chloride (PVC)/nylon terpolymer was reported in this article. Two compatibilizers were used in this study: one is a terpolymer of ethylene–n‐butyl acrylate–monoxide (EnBACO); the other is terpolymer of EnBACO grafted with maleic anhydride (EnBACO‐g‐MAH). The observation of scanning electron microscope (SEM) reveals that the PVC/nylon terpolymer blends have a two‐phase structure; and the nylon terpolymer phase is the continuous phase, and PVC domains in the PVC/nylon terpolymer/EnBACO‐g‐MAH blends have fine dispersion over a broad range of the PVC/nylon terpolymer ratio. EnBACO‐g‐MAH is more compatible with the nylon terpolymer than EnBACO. EnBACO and EnBACO‐g‐MAH have different effects on the glass transition temperatures of the PVC phase and nylon terpolymer phase in the blends. The notched Izod impact strength, tensile strength, elongation at break, Vicat softening temperature (VST), and melt flow index (MFI) critically depend on PVC/nylon terpolymer ratio, the kinds and concentration of the compatibilizers. The PVC/nylon terpolymer/EnBACO‐g‐MAH blends display a good combination of high toughness, high flowability, and high VST under low load. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2823–2832, 2001     

Study on the rheological behaviors of UHMWPE/CA‐MMT nanocomposite

In our previous study, we have prepared a novel antibacterial ultra‐high molecular weight polyethylene/chlorhexidine acetate‐montmorillonoid (UHMWPE/CA‐MMT) composites and examined its crystallization process and kinetics [1]. In this work, the rheological behaviors of pure UHMWPE, UHMWPE/MMT, UHMWPE/CA, and UHMWPE/CA‐MMT were characterized. The results showed that MMT can increase the viscosity of the polymer composites and CA can act as a plasticizer in the composites. Compared with UHMWPE/CA, UHMWPE/CA‐MMT had lower η*, G′, and G″. The TGA result indicated that CA‐MMT has higher thermostability than CA. Hence, CA‐MMT has the lower thermal decomposition ratio at high temperature than CA when it is blended with polymer. The TGA result could be used to explain that UHMWPE/CA‐MMT composites had better plasticizer effect than UHMWPE/CA composites. POLYM. COMPOS., 36:47–50, 2015. © 2014 The Authors Polymer Composites published by Wiley Periodicals, Inc.     

Effects of maleated styrene–(ethylene‐co‐butene)–styrene on compatibilization and properties of nylon‐12,12/nylon‐6 blends

Effects of a maleated triblock copolymer of styrene–(ethylene‐co‐butene)–styrene (SEBS‐g‐MA) on compatibilization and mechanical properties of nylon‐12,12/nylon‐6 blends were investigated. The results showed that addition of SEBS‐g‐MA could improve the compatibility between nylon‐12,12 and nylon‐6. Nylon‐12,12 could disperse very well in nylon‐6 matrix, although the dispersion of nylon‐6 was poor when nylon‐6 was the dispersed phase. At a fixed nylon‐12,12/nylon‐6 ratio of 30/70, supertoughness was achieved with addition of 15% SEBS‐g‐MA in weight. Scanning electron microscopy of the impact‐fractured surface indicated that cavitation and matrix shear yielding were the predominant mechanisms of impact energy dissipation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1446–1453, 2004     

Effects of molecular weight and grafted maleic anhydride of functionalized polylactic acid used in reactive compatibilized binary and ternary blends of polylactic acid and thermoplastic cassava starch

Polylactic acid (PLA) was reactively functionalized with maleic anhydride (MA) and 2,5‐bis(tert‐butylperoxy)?2,5‐dimethylhexane (Luperox 101 or L101) using a twin screw extruder (TSE). The effects of functionality (grafted MA level) and/or number average molecular weight of functionalized PLA (PLA‐g‐MA) as the reactive polymer pairs (binary blends) and reactive compatibilizer (ternary blends) were investigated. Due to the dominant side reaction during melt free radical grafting, polymer degradation or chain scission, PLA‐g‐MA having a higher grafted MA had lower molecular weights and intrinsic viscosity as well as broader molecular weight distribution values. The thermal, physical, mechanical, and morphological properties of binary blends produced by using the TSE and injection molding at a ratio of 70 wt % PLA‐g‐MA and 30 wt % thermoplastic cassava starch (TPCS) were analyzed. The reactive blends having grafted MA more than 0.4 wt % had poor tensile strength and elongation at break. Similar trends in morphology and tensile properties were observed in the reactive ternary blends. The use of PLA‐g‐MA strongly impacted the elongation at break but not the modulus or tensile strength. An increase of PLA‐g‐MA's number average molecular weight ( or M_n) improved the tensile properties of the blends. The reactive ternary blend having 0.1 wt % grafted MA on PLA and PLA‐g‐MA basis and PLA‐g‐MA's M_n of 45 kDa offered the highest elongation at break. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42230.     

Nylon‐coated ultra high molecular weight polyethylene fabric for enhanced penetration resistance

A coating of Nylon 6,6 or 6,12 was used to improve the penetration resistance of ultra high molecular weight polyethylene (UHMWPE) fabric that would be potentially useful in the manufacture of flexible body armor against spike/knife threats. Quasi‐static test results for the spike penetrator showed a 77% and 86% improvement in the puncture resistance of Nylon 6,6 and Nylon 6,12 coated UHMWPE (respectively) over a neat fabric target of equivalent areal densities. Dynamic impact testing demonstrated dramatic improvement in the puncture resistance of nylon‐coated fabrics while only a slight improvement in stab resistance was observed comparing samples with equivalent areal densities. Photography of ruptured areas after quasi‐static testing revealed limited fiber motion or fiber stretching with no evidence of fiber pullout for nylon‐coated fabric samples in contrast to neat fabric. This suggests that there was a significant increase in energy absorption by nylon‐coated fabrics at impact. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40350.