Crystallization behavior and UV‐protection property of PET‐ZnO nanocomposites prepared by in situ polymerization

The aim of this study was to investigate the crystallization behavior and UV‐protection property of polyethylene terephthalate (PET)‐ZnO nanocomposits. PET‐ZnO nanocomposites containing 0.5–3.0 wt % of ZnO were successfully synthesized by in situ polymerization. The Fourier transformed infrared (FTIR) spectroscopy indicated the silane coupling agent was anchored onto the surface of ZnO. Scanning electron microscope (SEM) images showed ZnO particles were dispersed homogeneously in PET matrix with amount of 0.5–1.0 wt %. Differential scanning calorimetry (DSC) results exhibited that the incorporation of ZnO into PET resulted in increase of the melting transition temperature (T_m) and crystallization temperature (T_c) of PET‐ZnO nanocomposites. The crystallization behavior of PET and PET‐ZnO nanocomposites was strongly affected by cooling rate. ZnO nanoparticles can act as an efficient nucleating agent to facilitate PET crystallization. UV–vis spectrophotometry showed that UV‐ray transmittance of PET‐ZnO nanocomposites decreased remarkably and reached the minimum value of 14.3% with 1.5 wt % of ZnO, compared with pure PET whose UV‐ray transmittance was 84.5%. PET‐ZnO nanocomposites exhibited better UV‐protection property than pure PET, especially in the range of UVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Carbon nanotubes induced crystallization of poly(ethylene terephthalate)

We have investigated the crystallization characteristics of melt compounded nanocomposites of poly(ethylene terephthalate) (PET) and single walled carbon nanotubes (SWNTs). Differential scanning calorimetry studies showed that SWNTs at weight fractions as low as 0.03 wt% enhance the rate of crystallization in PET, as the cooling nanocomposite melt crystallizes at a temperature 10 °C higher as compared to neat PET. Isothermal crystallization studies also revealed that SWNTs significantly accelerate the crystallization process. WAXD showed oriented crystallization of PET induced by oriented SWNTs in a randomized PET melt, indicating the role of SWNTs as nucleating sites.     

Transparent conductive film based on carbon nanotubes and PEDOT composites

Single-walled nanotubes (SWNTs), thin multiwalled carbon nanotubes (t-MWNTs) and multiwalled carbon nanotubes (MWNTs) were treated with H₂SO₄–HNO₃ acid solution, under different chemical conditions. The acid-treated CNTs were dispersed in DI water and in poly (3,4-ethylenedioxythiophene) (PEDOT) solution. Furthermore, the finely dispersed CNTs/PEDOT solutions were employed to a simple method of bar coating to obtain the transparent conductive films on the glass and polyethylene terephthalate (PET) film. A sheet resistance of 247 Ω/sq and a transmission of 84.7% were obtained at a concentration of the acid-treated CNTs of 0.01 wt.%.     

PET/碳纳米管共混物的研究进展

综述了聚对苯二甲酸乙二醇酯(PET)/碳纳米管(CNTs)的共混物的制备和性能。官能化CNTs比未官能化CNTs在PET母体中的分散性得到改善;PET/未官能化CNTs共混物和PET/官能化CNTs共混物相比PET,熔融结晶温度均增高,具有更高的结晶度;PET/未官能化CNTs共混物的熔点变化不大,而PET/官能化CNTs共混物的熔点的变化取决于官能化CNTs中引入官能团的化学结构;PET/未官能化CNTs共混物和PET/官能化CNTs共混物的熔体黏度均比PET有所提高,切力变稀行为比PET也有所增强;PET/未官能化CNTs共混物和PET/官能化CNTs共混物的热稳定性、导电性能及机械性能均得到改善。     

Multiwall‐carbon‐nanotube‐reinforced poly(ethylene terephthalate) nanocomposites by melt compounding

Poly(ethylene terephthalate) (PET) nanocomposites reinforced with multiwall carbon nanotubes (MWCNTs) were prepared through melt compounding in a twin‐screw extruder. The presence of MWCNTs, which acted as good nucleating agents, enhanced the crystallization of PET through heterogeneous nucleation. The incorporation of a small quantity of MWCNTs improved the thermal stability of the PET/MWCNT nanocomposites. The mechanical properties of the PET/MWCNT nanocomposites increased with even a small quantity of MWCNTs. There was a significant dependence of the rheological properties of the PET/MWCNT nanocomposites on the MWCNT content. The MWCNT loading increased the shear‐thinning nature of the polymer‐nanocomposite melt. The storage modulus and loss modulus of the PET/MWCNT nanocomposites increased with increasing frequency, and this increment effect was more pronounced at lower frequencies. At higher MWCNT contents, the dominant nanotube–nanotube interactions led to the formation of interconnected or networklike structures of MWCNTs in the PET/MWCNT nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1450–1457, 2007     

Morphology,crystallization, and mechanical properties of poly(ethylene terephthalate)/multiwalled carbon nanotubes composites

Poly(ethylene terephthalate)/multiwalled carbon nanotubes (PET/MWCNTs) with different MWCNTs loadings have been prepared by in situ polymerization of ethylene glycol (EG) containing dispersed MWCNTs and terephthalic acid (TPA). From scanning electronic microscopy images of nanocomposites, it can be clearly seen that the PET/MWCNTs composites with low‐MWCNTs contents (0.2 and 0.4 wt %) get better MWCNTs dispersion than analogous with high‐tube loadings (0.6 and 0.8 wt %). The nonisothermal crystallization kinetics was analyzed by differential scanning calorimetry using Mo kinetics equation, and the results showed that the incorporation of MWCNTs accelerates the crystallization process obviously. Mechanical testing shows that, in comparison with neat PET, the Young's modulus and the yield strength of the PET nanocomposites with incorporating 0.4 wt % MWCNTs are effectively improved by about 25% and 15%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Impact of injection‐molding processing parameters on the electrical,mechanical, and thermal properties of thermoplastic/carbon nanotube nanocomposites

Thermoplastic nanocomposites, based on high‐density polyethylene, polyamide 6, polyamide 66, poly(butylene terephthalate), or polycarbonate and containing multiwalled carbon nanotubes (CNTs), were compounded with either neat CNTs or commercial CNT master batches and injection‐molded for the evaluation of their electrical, mechanical, and thermal properties. The nanocomposites reached a percolation threshold within CNT concentrations of 2–5 wt %; however, the mechanical properties of the host polymers were affected. For some nanocomposites, better properties were achieved with neat CNTs, whereas for others, master batches were better. Then, polycarbonate and poly(butylene terephthalate), both with a CNT concentration of 3 wt %, were injection‐molded with a screening design of experiments (DOE) to evaluate the effects of the processing parameters on the properties of the nanocomposites. Although only a 10‐run screening DOE was performed, such effects were clearly observed. The volume resistivity was significantly dependent on the working temperature and varied up to 4 orders of magnitude. Other properties were also dependent on the processing parameters, albeit in a less pronounced fashion. Transmission electron microscopy indicated that conductive samples formed a percolation network, whereas nonconductive samples did not. In conclusion, injection‐molding parameters have a significant impact on the properties of polymer/CNT nanocomposites, and these parameters should be optimized to yield the best results. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

UHMWPE/CNTs复合纤维的结晶行为研究

分别用DSC、X衍射、热台偏光显微镜对超高分子质量聚乙烯（UHMWPE）和UHMWPE／CNTs（碳纳米管）复合纤维的结晶行为进行了研究。结果表明：碳纳米管的加入使得复合材料的熔点较UHMWPE有所提高,碳纳米管起到了成核剂的作用。晶片厚度较UHMWPE增加。     

Morphology,crystallization, and mechanical properties of poly(ethylene terephthalate)/multiwall carbon nanotube nanocomposites via in situ polymerization with very low content of multiwall carbon nanotubes

So far, the reported content of multiwall carbon nanotubes (MWNTs) in polymer/MWNTs nanocomposites is usually above 0.1 wt %. In this article, we will report our work on the study of the morphology, crystallization, and mechanical properties of poly(ethylene terephthalate) (PET)/MWNTs nanocomposites prepared by in situ polymerization with very low content of MWNTs (from 0.01 to 0.2 wt %). Well‐dispersed MWNTs with a big network throughout PET matrix were observed by SEM. The very small amount of MWNTs displayed a great nucleating effect on the PET crystallization. The crystallization temperature was improved for 6.4°C by using only 0.01 wt % MWNTs. The decreased chain mobility of PET by adding MWNTs was evident by the formation of imperfect or smaller/thinner crystallites with low melting temperature. An increased storage modulus was also achieved for the nanohybirds with MWNT content less than 0.05 wt %. Our result indicates that using very low content MWNTs (less than 0.1 wt %) is a simple way to achieve good dispersion, yet with remarkable enhancement for polymer/MWNTs modification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3695–3701, 2007     

Nonisothermal crystallization kinetics of poly(butylene terephthalate)/multiwalled carbon nanotubes nanocomposites prepared by in situ polymerization

Poly(butylene terephthalate)/multiwalled carbon nanotubes (PBT/MWNT) nanocomposites were prepared by in situ ring‐opening polymerization of cyclic butylene terephthalate oligomers (CBT). The nonisothermal crystallization behavior of the neat PBT and the PBT/MWNT nanocomposites was analyzed quantitatively. The results reveal that the combined Avrami/Ozawa equation exhibits great advantages in describing the nonisothermal crystallization of PBT and its nanocomposites. The presence of MWNTs has the nucleation effect promoting crystallization rate for the nanocomposites, and the maximum one is observed in the nanocomposite having 0.75 wt % MWNT content. On the other hand, the addition of MWNTs has the impeding effect reducing the chain mobility and retarding crystallization, which is confirmed by the crystallization activation energies. However, the nucleation effect of MWNTs plays the dominant role in the crystallization of PBT/MWNT nanocomposites, in other words, the incorporation of MWNTs is increasing the crystallization rate of the nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40849.     

Carbon nanotubes‐reinforced PET nanocomposite by melt‐compounding

Poly(ethylene terephthalate) (PET) nanocomposites with single‐walled carbon nanotubes (SWNTs) have been prepared by a simple melt compounding method. With increasing concentration (0–3 wt %) of SWNTs, the mechanical and dynamic mechanical properties improved, corresponding to effective reinforcement. Melt rheological characterization indicated the effective entanglements provided by SWNTs in the melt state as well. Thermogravimetric analysis suggested no influence of SWNTs on the thermal stability of PET. Electrical conductivity measurements on the composite films pointed out that the melt compounded SWNTs can result in electrical percolation albeit at concentrations exceeding 2 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Crystallization behavior of carbon nanotubes‐filled polyamide 1010

The nanocomposites of polyamide1010 (PA1010) filled with carbon nanotubes (CNTs) were prepared by melt mixing techniques. The isothermal melt‐crystallization kinetics and nonisothermal crystallization behavior of CNTs/PA1010 nanocomposites were investigated by differential scanning calorimetry. The peak temperature, melting point, half‐time of crystallization, enthalpy of crystallization, etc. were measured. Two stages of crystallization are observed, including primary crystallization and secondary crystallization. The isothermal crystallization was also described according to Avrami's approach. It has been shown that the addition of CNTs causes a remarkable increase in the overall crystallization rate of PA1010 and affects the mechanism of nucleation and growth of PA1010 crystals. The analysis of kinetic data according to nucleation theories shows that the increment in crystallization rate of CNTs/PA1010 composites results from the decrease in lateral surface free energy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3794–3800, 2006     

Hybrid clay‐carbon nanotube/PET composites: Preparation,processing, and analysis of physical properties

The aim of this work was the preparation of novel composites of poly(ethylene terephthalate) (PET) and nano‐hybrid systems based on clay used as catalyst for the growth of multi walled carbon nanotubes (Clay‐CNTs), through catalytic chemical vapor deposition (CCVD). The carbon content into the hybrid filler was 58.1 wt %. Composites with 1.0, 1.5, 2.0, 3.0 wt % of Clay–CNTs were obtained by melt compounding and processed using a microinjection molding press. Unfilled PET was processed in the same composites conditions. Structural characterization and physical properties (thermal, degradation, mechanical, and electrical) were analyzed and correlated to the hybrid filler loading, and carbon nanotubes amount. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40441.     

Melt crystallization of poly(ethylene terephthalate): Comparing addition of graphene vs. carbon nanotubes

Poly(ethylene terephthalate) (PET)-based nanocomposites with graphene or multi-wall carbon nanotubes (MWCNT) were prepared by melt mixing. Aspect ratio, A_f, and interparticle distance, λ, of graphene in the nanocomposites were obtained from melt rheology and transmission electron microscopy respectively. λ of PET/graphene nanocomposites was much smaller than λ in PET/MWCNT. For PET/graphene with highest A_f, λ became <1 μm at more than 0.5 wt% graphene. Non-isothermal crystallization behavior from the melt was investigated by differential scanning calorimetry. The crystallization temperatures suggest that the nucleation effect of graphene was stronger than that of MWCNT. The half crystallization time of PET/graphene became longer than PET/MWCNT with increasing graphene loading, suggesting that confinement by graphene suppressed the crystal growth rate. XRD analysis indicated that smaller crystals formed in PET/graphene than in PET/MWCNT. From Raman spectroscopy, the π–π interaction between PET and graphene was stronger than that between PET and MWCNT. This stronger interaction in PET/graphene appears to result in formation of crystals with higher perfection.     

纳米氧化物作为成核剂对PET结晶速率的影响

研究了成核剂纳米氧化镁和纳米氧化硅对聚对苯二甲酸乙二醇酯(PET)结晶速率的影响。通过等温结晶差热分析(DSC)研究了纳米氧化镁在不同含量、不同温度下对PET等温结晶行为的影响。用纳米氧化镁和纳米氧化硅填充PET体系的非等温结晶DSC,由所得冷结晶峰温度值和热结晶峰温度值的对比,探索纳米成核剂对PET结晶速率的影响及其规律。研究结果表明:纳米成核剂均能明显提高PET的结晶速率,而纳米氧化镁比纳米氧化硅对促进PET的结晶效果更好;添加不同含量的纳米氧化镁对PET在不同温度下的等温结晶影响不同,在所研究的范围内,1.0%的添加量较有利于PET的结晶。     

Nanocomposites of ultrahigh molar mass polyethylene and modified carbon nanotubes

In this work, the use of a laboratory twin-screw extruder was evaluated to process ultrahigh molar mass polyethylene and composites with carbon nanotubes (CNTs). Commercial polymer samples with lubricant (1%) and different percentages (0.01%, 0.05%, and 0.1%) of pure, oxidized, and chemically surface treated multi-walled carbon nanotubes (MWCNTs) were evaluated. The results showed that polymer melting and crystallization temperatures were not affected by CNTs, although an increase in the degree of crystallinity in all nanocomposites was observed along with a decrease in crystal size. Therefore, CNTs behaved as nucleating agents. All ultrahigh molar mass polyethylene (UHMWPE)/CNT samples showed increased initial degradation temperature, although this was not very great when introducing acetylated and stearic acid modified CNTs. Both oxidized CNTs and stearic acid CNTs did not markedly improve the composites' mechanical properties. Therefore, the nanocomposites containing pure CNTs and most of those with acetylated CNTs resulted in higher reinforcement for UHMWPE. The addition of the lubricant allowed the polymer matrix to be processed in the extruder, whereas the increase in CNT content in UHMWPE improved the stiffness of the material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47459     

Nonisothermal melt crystallization kinetics of poly(ethylene terephthalate)/Barite nanocomposites

Poly(ethylene terephthalate) (PET)/Barite nanocomposites were prepared by direct melt compounding. The nonisothermal melt crystallization kinetics of pure PET and PET/Barite nanocomposites, containing unmodified Barite and surface‐modified Barite (SABarite), was investigated by differential scanning calorimetry (DSC) under different cooling rates. With the addition of barite nanoparticles, the crystallization peak became wider and shifted to higher temperature and the crystallization rate increased. Several analysis methods were used to describe the nonisothermal crystallization behavior of pure PET and its nanocomposites. The Jeziorny modification of the Avrami analysis was only valid for describing the early stage of crystallization but was not able to describe the later stage of PET crystallization. Also, the Ozawa method failed to describe the nonisothermal crystallization behavior of PET. A combined Avrami and Ozawa equation, developed by Liu, was used to more accurately model the nonisothermal crystallization kinetics of PET. The crystallization activation energies calculated by Kissinger, Takhor, and Augis‐Bennett models were comparable. The results reveal that the different interfacial interactions between matrix and nanoparticles are responsible for the disparate effect on the crystallization ability of PET. POLYM. COMPOS., 31:1504–1514, 2010. © 2009 Society of Plastics Engineers     

TRANSCRYSTALLIZATION WITH REORIENTATION OF POLYETHYLENE IN A DRAWN PET/PE BLEND AS REVEALED BY WAXS OF SYNCHROTRON RADIATION

A cold drawn blend of poly(ethylene terephthalate) (PET) and polyethylene (PE) (50/50 by wt.) was investigated during heating, melting, and subsequent crystallization upon cooling of PE by means of wide-angle X-ray scattering (WAXS) of synchrotron radiation. Strong epitaxial effects of the highly oriented PET on the very first stages of non-isothermal crystallization of PE during cooling of the cold drawn blend from 160°C to room temperature were found. WAXS shows that transcrystalline PE layers are formed around the PET fibrils. Within these layers, the PE crystallites are partly oriented at 90° with respect to their initial orientation (draw direction).     

The characteristics of carbon nanotube‐reinforced poly(phenylene sulfide) nanocomposites

Multiwall carbon nanotube reinforced poly (phenylene sulfide) (PPS) nanocomposites were successfully fabricated through melt compounding. Structural, electrical, thermal, rheological, and mechanical properties of the nanocomposites were systematically studied as a function of carbon nanotube (CNT) fraction. Electrical conductivity of the polymer was dramatically enhanced at low loading level of the nanotubes; the electrical percolation threshold lay between 1 and 2 wt % of the CNTs. Rheological properties of the PPS nanocomposites also showed a sudden change with the CNT fraction; the percolation threshold was in the range of 0–0.5 wt % of CNTs. The difference in electrical and rheological percolation threshold was mainly due to the different requirements needed in the carbon nanotube network in different stages. The crystallization and melting behavior of CNT‐filled PPS nanocomposites were studied with differential scanning calorimetry; no new crystalline form of PPS was observed in the nanocomposites, but the crystallization rate was reduced. The thermal and mechanical properties of the nanocomposites were also investigated, and both of them showed significant increase with CNT fraction. For 5 wt % of CNT‐filled PPS composite, the onset of degradation temperature increased by about 13.5°C, the modulus increased by about 33%, and tensile strength increased by about 172%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009