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1.
    
Strain rate dependency is an important issue for the mechanical response of materials in impact events. Dynamic mechanical properties of a high‐strength poly(methyl methacrylate) (PMMA) were studied by using split Hopkinson pressure bar technology. The maximum stress is enhanced with the increase of strain rate, and then keeps a constant with the further increase of strain rate, which is accompanied with a linear increase of fracture energy density. The critical data of strain rate and maximum stress were determined. Eyring's equation was applied for analyzing the influence factors, which relate to the hardening induced by strain rate and softening caused by adiabatic temperature rise. Inherent physical mechanisms were clarified and the strategies for designing advanced impact‐resistant polymers were proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46189.  相似文献   

2.
    
To overcome serious rigidity depression of rubber‐toughened plastics and fabricate a rigidity‐toughness balanced thermoplastic, a combination of styrene‐[ethylene‐(ethylene‐propylene)]‐styrene block copolymer (SEEPS) and ethylene‐propylene rubber (EPR) was used to toughen polypropylene. The dynamic mechanical properties, crystallization and melting behavior, and mechanical properties of polypropylene (PP)/EPR/SEEPS blends were studied in detail. The results show that the combination of SEEPS and EPR can achieve the tremendous improvement of low‐temperature toughness without significant strength and rigidity loss. Dynamic mechanical properties and phase morphology results demonstrate that there is a good interfacial strength and increased loss of compound rubber phase comprised of EPR component and EP domain of SEEPS. Compared with PP/EPR binary blends, although neither glass transition temperature (Tg) of the rubber phase nor Tg of PP matrix in PP/EPR/SEEPS blends decreases, the brittle‐tough transition temperature (Tbd) of PP/EPR/SEEPS blends decreases, indicating that the increased interfacial interaction between PP matrix and compound rubber phase is also an effective approach to decrease Tbd of the blends so as to improve low‐temperature toughness. The balance between rigidity and toughness of PP/EPR/SEEPS blends is ascribed to the synergistic effect of EPR and SEEPS on toughening PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45714.  相似文献   

3.
    
Amide maleic anhydride‐g‐liquid polybutadience (AMALPB) was synthesized using maleic anhydride‐g‐liquid polybutadience (MALPB) with ethylenediamine (EDA), and its structure was confirmed by FTIR and 1H‐nuclear magnetic resonance spectra, respectively. It was then used as a reactive toughening agent to make blends with diglycidyl end‐capped poly(bisphenol‐A‐co‐epichlorohydrin epoxy cured at room temperature. Their thermal decomposing behaviors did not show much difference because both EDA and AMALPB possessed similar aliphatic groups. All their glass transition temperatures (Tg) increased more than 10 °C than that of the neat epoxy, and with the addition of AMALPB, the blends were greatly strengthened upon heating as show from their storage moduli. When AMALPB was added at 10 wt %, its elongation at break increases to a maximum of 8.8% which was about two times higher than that of the neat epoxy, and its tensile strength also increased. However, the excessive addition of AMALPB resulted in an apparent decline in their tensile strength at content above 20%. The simultaneous improvements in both tensile strength and strain were attributed to the existence of well‐dispersed rubber particles in the continuous matrices performing plastic deformation that resulted from the chemical bonds of interfaces among the rubber particles and matrix, and meanwhile, inducing the deflection of the cracks. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45985.  相似文献   

4.
    
Understanding the interfacial interactions plays a key role in controlling mechanical and physical properties of polymer/clay nanocomposites (PCNs). In this work, the surface interactions between constituents of experimentally prepared PCNs which are the pristine linear low density polyethylene (PE) chains, PE compatibilizers, montmorillonite clay surface layer, and surfactants were studied quantitatively by employing molecular dynamics simulation technique. The interaction energy between the polymer and the clay was found to be inversely proportional with the volume of the surfactant which decreases the electrostatic interactions between the compatibilizer and the hydrophilic clay surface. However, the van der Waals (vdW) interactions between alkyl tails of surfactants and the PE chains increase with the tail length of the surfactants. The most attractive interaction was between the surfactant's head group and the clay surface. We showed that there existed fine balance between the electrostatic and vdW type forces on the stability and the enhanced properties of the PE–organoclay nanocomposites. Calculated interaction energies were then correlated to the experimentally measured mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45817.  相似文献   

5.
    
The effect of interface property on the mechanical behavior of silica–polybutadiene composites is systematically investigated via combined experimental and dynamics simulation. In experiment, the interface property is controlled by SiO2 particle size, silane coupling agents, and silane grafting density. The effects of these control parameters on the vulcanization kinetics, tensile strength, and dynamic mechanic properties are investigated and discussed. Both the experimental and simulation studies reveal the pivot role of filler–polymer interface on the mechanical reinforcement. Simulation study reveals that the constrained polymer layer (～12 nm) surrounding the silica particles shows increased stress from 30 to 230 MPa, which is identified as the major reason for the overall enhancement of 100% modulus from 0.8 to 1.6 MPa. The molecular mechanics of interface from simulation is well correlated to the experimental results in this study, which provides a molecular level understanding of the relationship between interfacial interaction and mechanical reinforcement. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46089.  相似文献   

6.
    
Initial consuming properties of polypropylene (PP) based composite tape yarns having different portions of ultraviolet (UV) light stabilizer are studied. In many cases, the samples with different portions of UV light stabilizer exhibit changes at level of initial properties, that is, the statistically significant side effects are obtained. When portion of the additive increases, the initial values of width, thickness and linear density of the modified samples are found to be reduced. The additions of UV light stabilizer also generate the statistically significant changes for the most tensile characteristics. The linear and second order polynomial equations are suggested to show the side effects on the properties. Some visual changes in morphology, that is, the differences in smoothness of the surfaces of the samples are also noticed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44400.  相似文献   

7.
    
Thermomechanical, mechanical and fracture mechanical properties of modified epoxy resins with two different modifiers are investigated. Carboxyl‐terminated butadiene‐acrylonitrile (CTBN) is used as toughening agent and hexanediole diglycidyl ether (HDDGE) as reactive diluent. Both modifiers are admixed in contents from 0 up to 100 phr (parts per hundred resin) and exhibit flexibilizing and toughening qualities. The glass transition temperature is strongly depressed by the admixed reactive diluent, whereas the tensile modulus exhibits greater dependency on the toughening agent contents. The tensile strength and strain at break values are higher for the formulations with diluent compared to resins with toughening agent. Up to a content of 45 phr both modified systems exhibit comparable fracture toughness values. Only the toughened systems comprise increasing values for modifier amounts higher than 45 phr. For the formulation with both modifiers (toughening agent and diluent) a significantly higher toughness but a reduced glass transition temperature was obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45348.  相似文献   

8.
    
Epoxidized natural rubber (ENR)–silica hybrids without any other additives were prepared by an open‐mill mixing method at room temperature. The curing characteristics, crosslinking density, mechanical properties, and dynamical mechanical properties were investigated. The results indicate that the ENR–silica hybrid materials could be cured with silica as a crosslinking and reinforcing agent. Attenuated total reflection–Fourier transform infrared spectroscopy and solid‐state 13C‐NMR spectroscopy exposed the characteristics of the interfacial interaction in the hybrids and confirmed the existence of chemical bonds and hydrogen bonds between the epoxy group and Si? OH. Scanning electron microscopy illustrated a good dispersion of silica in the ENR matrix. Meanwhile, the modulus at 100% elongation of the hybrid reached 9.64 MPa when 100‐phr silica was loaded; a similar trend was observed for the hardness. Finally, our findings might extend the concept of rubber curing and open a new space for making an environmentally friendly rubber composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44605.  相似文献   

9.
    
A series of thermal insulation, acoustic absorption isocyanate‐based lightweight polyimide (PI) foams with 4,4′‐diaminodiphenyl ether (ODA) units were prepared from polyaryl polymethylene isocyanate (PAPI) and the esterification solution derived from pyromellitic dianhydride (PMDA) and ODA. The structures and properties of the PI foams prepared with different molar ratio of ODA/PMDA were investigated in detail. The results show that the ODA units have great influence on the foam properties. With the increase of the ODA units, the density decreases firstly and then increases. When the molar ratio of ODA/PMDA is 3/10, the foam reaches the minimum density (13.7 kg/m3). Moreover, with increasing the ODA units, the acoustic absorption properties increase firstly and then decrease owing to the variation of the average cell diameter of the PI foams. All PI foams show excellent thermal stability, and the 5% and 10% weight loss temperature are in the range of 250–270 °C and 295–310 °C, respectively. In addition, the PI foams present low thermal conductivity and thermal diffusivity. Furthermore, the mechanical property was also evaluated and the compressive strength of the PI foams is in the range of 33.0–45.7 kPa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46029.  相似文献   

10.
    
Triblock copolymer (TCP)‐based thermoplastic elastomers (TPEs) were designed via reversible addition–fragmentation chain‐transfer emulsion polymerization. Short isobornyl methacrylate (IM) building blocks in the two ends of molecular chain were incorporated to guarantee the mechanical properties of the TPEs at high temperature (i.e., heat resistance) because of the high glass‐transition temperature (Tg) of poly(isobornyl methacrylate) (PIM; ～180 °C). The microphase separation, tensile properties at different temperatures, dynamic mechanical properties, oil resistance, and thermal stability of the TPEs were extensively characterized. The TPEs had distinct microphase separation with a wide inter‐Tg interval (150–185 °C). The tensile strength and elongation at break of the TPEs decreased with increasing temperature from 25 to 100 °C because of the reduced interactions in the phase domain. Even so, the TPEs had a high elongation at break beyond 200% and little change in the tensile strength even at 100 °C together with a wide quasi‐platform stage between the Tg values in dynamic mechanical analysis; this indicated good heat resistance. Meanwhile, the TPEs had an enhanced oil resistance and a thermal stability higher than 300 °C. These TCP‐based TPEs with heat and oil resistance broaden the application potential in practical fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45379.  相似文献   

11.
    
The effect of the spinning speed on structural and thermal properties of polyacrylonitrile (PAN) fibers prepared by plasticized spinning was investigated. The PAN fibers were characterized by scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. We found that the surface morphology of the fibers was relatively smooth. The presence of a small amount of surface defects was caused by the instability of spinning process. The final fibers may have had two tensile fracture modes, that is, cluster breaking and axial split fracture. The structure of the as‐spun fibers was destroyed when the spinning speed was up to 500 m/min; this led to chain scission in the amorphous region. The final fibers exhibited mechanical properties that were roughly comparable to those of commercial PAN fibers. The changing trend in the cyclization temperature of the final fibers was consistent with that of crystallinity, which first increased and then decreased. The decomposition temperature in the amorphous region increased with increasing spinning speed. The decomposition temperature in the crystalline region increased with increasing crystallinity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45267.  相似文献   

12.
    
The styrene–butadiene–styrene block copolymer (SBS)/polypropylene (PP) blends with a unique sandwich layered co‐continuous structure were prepared by melt compounding. Differing from single conventional co‐continuous and sandwich structure, this structure was formed, where pure PP and co‐continuous SBS/PP phase acting as the face sheets and core. Even though the volume content was 20 or 10 vol %, PP always amazingly formed a continuous phase in SBS/PP blends, whereas the morphology of SBS phase relatively changed from dispersed particles to continuous network as its content increased to 50 vol %. For immiscible SBS/PP blends, due to the huge difference of complex viscosity and surface tension between SBS and PP, a pure PP layer existed on the surface of blends which can be ascribed to the PP enrichment. Herein, the structure of blends with more than 50 vol % SBS was presented as sandwich layered co‐continuous structure by combining the pure PP layer and co‐continuous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46580.  相似文献   

13.
    
A series of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) loaded with various contents of layered double hydroxides (LDHs) nanoparticles were prepared via a melt mixing method. Detailed investigations on LDH dispersion state in the polymeric matrix conducted by TEM revealed intercalated/exfoliated, and agglomerated structures at low (1 wt %) and high (>3 wt %) loadings of LDH contents, respectively. Wide angle X‐ray scattering and DSC results showed that incorporation of LDH into PVDF‐HFP matrix reduced its overall crystallinity and helped to form polar crystallites, while the crystal size at 020 crystallographic directions was found to be most affected by presence and dispersion state of LDH in the matrix. TGA results showed LDH improved thermal stability of matrix however, unlike many other nanomaterials it significantly reduced the residual mass which highlights catalytic role of LDH in degradation of residual carbon char. Detailed analysis on creep and recovery data over wide range of selected temperatures revealed that the creep compliance of nanocomposites are basically controlled by crystallinity and presence of LDH at low and high temperatures, respectively. Based on obtained storage modulus and creep compliance master curves it was also found that the influence of LDH on decreasing the creep compliance and improving viscoelastic properties of PVDF‐HFP over long time period and over high frequency ranges becomes more pronounced. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46352.  相似文献   

14.
    
The enhancement of mechanical properties were achieved by solution blending of poly(d ‐lactide) (PDLA) and 5‐arm poly(l ‐lactide) (5‐arm PLLA). Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) results indicated almost complete stereocomplex could be obtained when 5‐arm PLLA exceeded 30wt %. Tensile test results showed that the addition of 5‐arm PLLA in linear PDLA gave dramatically improvement both on tensile strength and elongation at break, which generally could not be increased simultaneously. Furthermore, this work transformed PDLA from brittle polymer into tough and flexible materials. The mechanism was proposed based on the TEM results: the stereocomplex crystallites formed during solvent evaporation on the blends were small enough (100–200 nm), which played the role of physical crosslinking points and increased the interaction strength between PDLA and 5‐arm PLLA molecules, giving the blends high tensile strength and elongation at break. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42857.  相似文献   

15.
    
Several polyacrylonitrile (PAN)/tea polyphenol (TP) blends were prepared with various mixing weight ratios (percentage). With a commercial acrylonitrile–butadiene–styrene (ABS) as reference, the results show that the PAN/TP blends with 12.5 wt % TP had a better antiwear ability and similar hardness to those of ABS. All of the prepared PAN/TP blends showed a lower impact strength than the referenced ABS. However, some values were indeed higher than those reported for engineering materials in the literature, for example, polystyrenes and some ABS blends. Differential scanning calorimetry, differential thermogravimetry, and dynamic mechanical analysis indicated that the PAN/TP blends had enhanced the thermal stability compared to the pure PAN. Fourier transform infrared spectral analysis suggested that the H bonds increased in the PAN/TP blends. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40411.  相似文献   

16.
    
In this article, we experimentally investigate the structure–property relationships of an acrylonitrile butadiene styrene (ABS) copolymer for fatigue and use a microstructure‐based multistage fatigue (MSF) model to predict material failure. The MSF model comprises three stages of fatigue damage (crack incubation, small crack growth, and long crack growth) that was originally used for metal alloys. This study shows for the first time that the MSF theory is general enough to apply to polymer systems like ABS. The experimental study included monotonic testing (compression and tension) and fully reversed uniaxial cyclic tests at two frequencies (1 Hz and 10 Hz) with a range of strain amplitudes of 0.006 to 0.04. Cyclical softening was observed in the ABS copolymer. Fractography studies of failed specimens revealed that particles were responsible for crack incubation. Although polymeric materials can be argued to be more complex in terms of failure modes and thermo‐mechano‐chemical sensitivity when compared with most metal alloys, results showed that the MSF model could be extended successfully to capture microstructural effects to polymeric materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40882.  相似文献   

17.
    
In this work, multiwalled carbon nanotubes (MWCNTs), as reinforcing agent, were blended with linear low‐density polyethylene (LLDPE), then molded by hot compression molding to prepare LLDPE/MWCNTs composites. Tensile tests indicate that the strength, Young's modulus, and toughness are all improved for LLDPE/MWCNTs composites containing 1 and 3 wt % MWCNTs. Compared with LLDPE, the Young's modulus of LLDPE/MWCNTs composites rises from 144.8 to 270.8 MPa at 1 wt % MWCNTs content. At the same time, increases of 18.5% in tensile strength and 16.6% in yield strength are achieved. Additionally, its toughness is enhanced by 26.7% than that of LLDPE. Microstructure characterizations, including differential scanning calorimetry, X‐ray diffraction, and scanning electron microscopy were performed to investigate the variations of microstructure and further to establish the relationship between microstructure and mechanical properties. Homogeneous dispersion of MWCNTs, network formation, and development of an oriented nanohybrid shish‐kebab structure contribute to the enhanced strength and toughness. The increased crystallinity is beneficial to the reinforcement and increased modulus. Additionally, the thermal stability of the LLDPE/MWCNTs composites is enhanced as well. This work suggests a promising routine to optimize polymer/MWCNTs composites by tailoring the structural development. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45525.  相似文献   

18.
    
Poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blends containing different amounts of PVP (0, 10, 25, 50, and 100 wt %) prepared by a solution casting method were characterized in terms of microstructure, thermal, and mechanical properties along with their drug release behavior. Fourier‐transform infrared spectroscopy results confirmed formation of hydrogen bonds between PEO and PVP. Although scanning electron microscopy micrographs showed no phase separation in the blends, the elemental analysis data obtained by energy dispersive X‐ray technique revealed partial miscibility between the blend components. The miscibility of the blend and degree of crystallinity of PEO component of the blend were decreased with increasing PVP content of the blend. The nucleating role of PVP in crystallization of PEO was confirmed by differential scanning calorimetry analysis. A synergistic effect on mechanical properties was obtained as a result of blending PVP with PEO. The results of curcumin release studies from the films indicated that, the blends have lower diffusion coefficients and slower drug release rate as compared to the neat PEO. Theoretical analysis of the drug release data using Peppas's model revealed that the kinetic of drug release from all the films is governed by a non‐Fickian diffusion mechanism. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46403.  相似文献   

19.
The effect of poly (lactic acid) (PLA) on the crystalline phase transition of poly (vinylidene fluoride) (PVDF) from α‐ to β‐phase under uniaxial stretching for immiscible PVDF/ PLA blends was investigated. The typical sea‐island structure in the blends was found to facilitate the necking of PVDF and the transition from α‐ to β‐phase due to the local stress distribution during stretching. The crystalline phase transition of PVDF in the blends is temperature‐dependent and is affected by the content of PLA. The highest content of β‐phase, F(β), was achieved in the samples stretched at 60°C, while the effect of PLA content on the crystalline phase transition of PVDF is more complex. F(β) increases slightly when the sample with a PLA content no more than 15 wt % is stretched at 60, 80, and 100°C, and decreases sharply for the sample containing 20 wt % PLA; in addition, the sample containing 10 wt % PLA exhibits the highest F(β) no matter what the stretching temperature is. The mechanism of the crystalline phase transition of PVDF during the stretching is interpreted from energy barrier of the transition from α‐ to β‐phase and the morphological structures in the blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

20.
    
This work studied the properties of spent coffee ground (SCG) filled natural rubber (NR). The SCG was initially characterized by various techniques, prior to being added into rubber. Results revealed that SCG had relatively large particle size with very low specific surface area. It is mainly composed of organic compounds (such as protein, fatty acid, cellulose, hemicellulose, and lignin) with small quantity of inorganic substances (oxides of potassium, silicon, magnesium, calcium, and phosphorous). The incorporation of SCG in NR gave relatively low reinforcement and tended to retard vulcanization due to the presence of hydroxyl groups on the SCG surface. In addition to untreated SCG, reinforcement of SCG treated by liquid epoxidized natural rubber (LENR) and bis ‐ ( 3‐ triethoxysilylpropyl) tetrasulfide (TESPT) was investigated. Improvement of rubber properties was observed when SCG surface was treated. Overall, TESPT‐treated SCG gave the rubber with the highest mechanical properties, followed by LENR‐treated SCG and untreated SCG, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46060.  相似文献   

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