The effects of electron beam radiation on material properties and degradation of commercial PBAT/PLA blend

This work investigates the potential application of e-beam radiation for sterilization of food packaging made of commercial polyester blend of poly(butylene adipate-co-terephthalate) and polylactide known under the trade name Ecovio 23B1. Ecovio film was irradiated at doses of 5, 13, and 26 kGy and the effect of sterilization on the microorganism inactivation ability was performed. The influence of radiation doses on structural and packaging properties such as tensile strength, barrier, and migration properties was also studied. ¹H NMR and FTIR analysis revealed no significant changes in the polymer structure, however, the molar mass of irradiated samples decreased with increasing radiation dose. This result indicated the occurrence of degradation process during radiation, which was confirmed by the thermal analysis and accelerated enzymatic degradation. The packaging properties did not changed significantly and the overall migration for 10% ethanol, isooctane, and MPPO was below the limit for all of the studied samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48462.     

Radiation degradation and stability of PBAT: copolymer of aromatic and aliphatic esters

Effect of the exposure of poly(butylene adipate‐co‐terephthalate) (PBAT) to ionizing radiation was studied by means of EPR and diffuse reflection spectroscopy, GC, and gel permeation chromatography. In addition, the influence of radiation‐induced processes on mechanical and rheological properties for the doses in the range 0–200 kGy was investigated. The macroscopic consequences of PBAT irradiation included: crosslinking, chain cleavage, and oxidation, which led to the significant modification of physicochemical features. The crosslinking process occurred even under cryogenic conditions and was confirmed by reduction in melt flow index (MFI), increase in viscosity, and weight‐average molecular weight with increasing dose. Material degradation during long‐term storage was accompanied by deterioration of mechanical properties, increase in MFI, and viscosity reduction. Oxidation of the copolyester had a chain character and increased over time, especially in the case of irradiated PBAT. Despite the presence of aromatic rings dissipating energy, the material is susceptible to ionizing radiation. The regions containing terephthalates are involved in the aging processes; the appropriate mechanisms have been proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46682.     

双增PLA/PBAT/TiO2复合材料的制备及性能研究

以机械共混的方法制备聚乳酸(PLA)/聚己二酸/对苯二甲酸丁二酯(PBAT)/Ti O2复合材料,对复合材料的热性能、力学性能和晶体结构进行研究与分析。研究发现:PBAT与Ti O2的加入能增韧增强PLA/PBAT/Ti O2复合材料,并能提高复合材料的热稳定性;随着PBAT含量的增加,PLA/PBAT/Ti O2复合材料的断裂伸长率先增后减,拉伸强度先不变后急剧下降,当PBAT含量为40%时样品的断裂伸长率达到极大值,PBAT含量为50%时样品的拉伸强度急剧下降;在熔融过程中,PLA/PBAT/Ti O2复合材料存在玻璃化转变、冷结晶行为和双重熔融转变;且复合材料存在PLA的两种晶型结构-α和β晶型。     

A new approach for flexible PBAT/PLA/CaCO3 films into agriculture

The use of flexible films in agriculture has increased intensely in the last 15 years bringing benefits to producers. However, environmental impacts increased due to their incorrect post‐use disposal which leads the degradable films to emerge as an alternative. The production films of poly(butylene adipate‐co‐terephthalate) and poly(lactic acid) reinforced with calcium carbonate (CaCO₃) was studied focusing on producing lower cost materials and flexible films. Four different films (reinforcement compositions) were prepared by melt extrusion with 10 and 20 wt % of CaCO₃. Mechanical and thermal properties, crystallinity, water absorption, and soil degradation, were evaluated. The addition of reinforcement leads to improved compatibility between the polymers in the matrix, which usually presented phase segregation. The films showed better mechanical properties with the addition of CaCO₃. Highly orientated amorphous structures were obtained leading to low water absorption and low degradation in the simulated soil. This low degradation, suggests that the obtained films would be of interest in flexible mulch films manufacturing, particularly for Muridori plantation system, where long‐term plantations are needed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46660.     

Enhanced degradation properties of polypropylene integrated with iron and cobalt stearates and its synthetic application

Synthetic plastic leads to environmental contamination, and a promising solution to this problem is to use prooxidants as fillers within them to speed up the photooxidation and thermooxidation processes. This makes plastics more susceptible to biodegradation. In this study, the degradation properties of the widely used polymer polypropylene (PP) were improved by integration with cobalt stearate (CoSt₂) and iron stearate (FeSt₃) as prooxidants with accelerating weathering degradation. The metal stearates were blended with PP in the concentration range 0.1–0.9% w/w. The properties of the blends were studied by mechanical properties testing, thermogravimetric analysis, differential scanning calorimetry, and water absorption measurement. We performed the degradation properties and thermooxidative studies by conducting an accelerated weathering test on PP–metal salt blends. Fourier transform infrared spectroscopy and scanning electron microscopy analysis of the samples before and after the accelerated weathering test were performed to study the extent of degradation in PP‐based metal salt blends. The results indicate that the tensile strength was inversely proportional to the concentration of metal stearates, and the samples showed an increased degree in polymer crystallinity (PPFe5 > PPCo5), and this led to the degradation of PP in less time. CoSt₂ predominantly enhanced the degradation of PP in comparison to FeSt₃. Food containers and pots were constructed with the tailored polymers of PP in the injection‐molding machine. Thus, metal‐stearate‐integrated polymers have great industrial potential to generate value‐added products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46028.     

PLA/PBAT/绢云母复合材料制备与性能

采用熔融共混技术制备了聚乳酸(PLA)/聚己二酸对苯二甲酸丁二酯(PBAT)复合材料、PLA/绢云母复合材料以及PLA/PBAT/绢云母三元复合材料,以拉伸强度、弯曲强度、断裂伸长率和冲击强度为参数,探究了PBAT和绢云母的用量对PLA基复合材料力学性能的影响.实验结果表明,PLA/PBAT/绢云母复合材料的最佳质量配...     

Thermal and photochemical degradation of PPO/HIPS blends

In general, polymer blends show a degradation behavior different from a simple combination of the individual components, making any forecast difficult without experiments. Interactions between polymers can sensibilize or stabilize the blend against degradation. In this work, the thermal and photooxidative degradation of blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) and high impact polystyrene (HIPS) have been studied under accelerated conditions. The extent of degradation was accompanied by infrared spectroscopy (FTIR) and Raman spectroscopy (FT‐Raman) and impact resistance and strain–stress testing followed its influence on the macroscopic properties of the blends. The results showed that HIPS and the blend containing 60 wt % of PPO are more susceptible to thermal and photochemical degradation, while the blends containing 40 and 50 wt % of PPO are more stable. Infrared and Raman spectroscopic analyses showed that the degradation of HIPS and its blends is caused not only by degradation of the polybutadiene phase. Effects of interactions, such as exchange of energy in excited state between the PPO and PS components of the polymeric matrix may also be responsible for the degradation and loss of mechanical properties of the PPO/HIPS blends. The chemical degradation directly affects the mechanical properties of the samples with photodegradation being more harmful than the thermal degradation at 75°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

磷酸二氢钾的制备工艺

简要论述了磷酸二氢钾的各种制备方法 ,并认为采用湿法磷酸及氯化钾取代热法磷酸和钾碱制备磷酸二氢钾是有利的     

The effect of UV irradiation on the electrospun PCL/TiO2 composites fibers

The effect of UV irradiation and micro‐ and nano‐TiO₂ as well as titanate nanotubes (TiNT) on the phase morphology and thermal properties of the electrospun PCL composite fibers was investigated. Polycaprolactone (PCL)/TiO₂ (micro‐ and nano‐TiO₂ as well as titanate nanotubes) composite fibers were prepared by electrospinning a polymer solution. The PCL and PCL/TiO₂ composite fibers were exposed to UV light at irradiation times of 5 and 10 days. After UV irradiation the crystallinity of the electrospun PCL/TiNTcomposite fibers increased because of the large specific surface area of TiNT. The thermal stability of the PCL/TiNT electrospun composite fibers increased due to the formation of crosslinking structure after UV irradiation. The SEM analysis suggests that after UV radiation the fibers showed high degree of degradation due to the high number of fibers breakages and fibers surface voids. The results of FTIR spectroscopy confirmed that the TiO₂ particles enhance the degradation process because of their photocatalytic activity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43539.     

Optical activity and electrogyration of KH2PO4

Accurate measurements of gyration tensors g₁₁ (=-g₂₂) and electrogyration effect of KH₂PO₄ were made by applying the improved HAUP method. g₁₁ diverges conspicuously when the temperature approaches Tc from above and below it, the behaviour being analyzed as obeying the Curie-Weiss law with a Curie-Weiss constant of 7.35×10^-4 K. An electrogyration coefficient π₁₃ referring to the polarization manifests a characteristic nature of improper ferroelectrics.     

Effects of alkali treatment on the properties of WF/PLA composites

In this study, composites of thermoplastic poly (lactic acid) filled with wood flour (WF) were prepared via melt extrusion. Before that, alkali treatment was performed on WF to improve the properties of the WF/PLA composite materials. The effect of the solution concentrations of NaOH, namely 0.5, 1.0, 5.0, and 10.0%, on mechanical properties of the composites was evaluated. The results showed that the properties of the composites with treated WF were enhanced greatly compared with that of the untreated composites. The composites had a best improvement in its compatibility and mechanical strength when the concentration of NaOH solution was 5.0%. The brittle fracture of composites showed that the chemical modification of WFs improved the compatibility between the filler and matrix.     

Effects of nitrogen and carbon dioxide gases on the degradation of low‐density polyethylene during extrusion and origin of the color

The effect of inert gases, nitrogen and carbon dioxide, on the oxidative degradation of low‐density polyethylene appearing as colored spots has been studied during an extrusion process in competition with an antioxidant. Extrusion under inert gases significantly decreases the degradation level in the critical region of the process in comparison with classical extrusion under air. The effect of antioxidants on degradation during extrusion at a high temperature is weak. The main processes acting on this reduction of polymer oxidation and the origin of the color of degraded domains have been investigated. Energy‐dispersive spectra of particles have confirmed that degradation is caused by thermooxidation. The nature of chromophore groups in degraded areas has been identified by IR microscopy. We found that β‐conjugated ketoenols are present inside colored spots and seem to be responsible for the color of degraded parts. Quantum calculations have confirmed that such chemical structures absorb visible light and create reddish and brown colors. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and degradation of PLA/chitosan composite materials

As scaffold material, poly(lactic acid) (PLA) has several obvious weaknesses, such as fast biodegradation, acidic degradation product, and hydrophobicity. To solve these problems, a series of PLA/chitosan composite materials was prepared in this study. SEC observation, porosity tests and contact angle measurements showed that the materials were hydrophilic and had appropriate porosity and structure, which were favorable to the cell growth. Degrading tests in vitro indicated that the degrading speeds of the materials were slower than that of PLA, and the materials could keep adjacently litmusless, certain shape and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 274–277, 2004     

Influence of melt processing on biodegradable nisin‐PBAT films intended for active food packaging applications

Biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) films incorporated with different levels of the antimicrobial peptide nisin were developed by melt processing. Structural, morphological, thermal, mechanical, and antimicrobial properties of the films were determined. The X‐ray diffraction patterns exhibited decreasing levels of intensity at 2θ values as the concentration of nisin increased. Scanning electron microscopy showed a heterogeneous morphology when higher amounts of nisin were incorporated. The antimicrobial films tested presented no significant differences in the melting temperature (123–125°C), and the crystallization temperature ranged from 69 to 75°C. The addition of nisin caused no significant modification in tensile strength values. However, results of Young's modulus and deformation at break differed significantly among samples. Active films demonstrated inhibition against the Gram‐positive bacterium Listeria monocytogenes. These results demonstrated that PBAT/nisin films produced by melt processing present a great potential for use as active food packaging materials aiming enhanced food safety. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43212.     

Electrical and thermal phenomena in low-density polyethylene/carbon black composites near the percolation threshold

Low-density polyethylene (LDPE)/carbon black (CB) composites were fabricated via melt-compounding technique. The percolation threshold was found to be around 20 wt % CB, and an electrical network formed by conductive CB was proven by scanning electron microscopy investigation. Dielectric responses depicted an interfacial relaxation peak at 20 wt % CB content. LDPE/CB composites showed an electric field-dependent conductivity as and a hysteresis behavior around the percolation threshold region. The CB particles with high thermal conductivity increased the heat conductance of the LDPE/CB20 up to 56%. The dynamic mechanical analysis of the LDPE/CB composites exhibited a noticeable contribution of CB throughout the composites, increasing the storage and loss modulus. The physical interactions between CB particles in the filler network enhanced the thermal degradation of the LDPE/CB25 composite for more than 76°C. The maximum breakdown strength of the LDPE/CB composites appeared with an approximately 10% improvement for LDPE/CB5 than pure LDPE. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47043.     

Modification of wood flour/PLA composites by reactive extrusion with maleic anhydride

MA modified wood flour/PLA composites were prepared by one‐step reactive extrusion, in which wood flour and poly(lactic acid) (PLA) were used as raw material, maleic anhydride (MA) was used as modifier, and dicumyl peroxide (DCP) was used as initiator. The influences of MA concentration on the morphology, thermal stability, rheological, and mechanical properties of the composites were studied. The addition of MA improved the compatibility of the composites significantly. The thermal and rheological results showed that with the increase of the concentration of MA, the thermal stability of the composites decreased, the storage modulus and complex viscosity of the composites also decreased. The MA modified composites had an enhanced mechanical strength compared to the unmodified one. As the concentration of the MA increased, the tensile and flexural strength of the composites first increased and then decreased, and reached a maximum when the concentration of MA was 1 wt %. The MA modified composites showed a better water resistance than the unmodified ones. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43295.     

Behavior of UV‐cured print inks on LDPE and PBAT/TPS blend substrates during curing,postcuring, and accelerated degradation

During radiation curing, a reactive formulation is converted into a highly crosslinked coating film by means of polymerization reactions. This three‐dimensional (3D) network is resistant to external degrading factors as it cannot be undone by any physical–chemical means. In this study, various ultraviolet (UV)‐curable ink formulations with different pigments were developed. The behavior of the UV‐curable inks was evaluated during UV curing in a photocalorimeter or in a UV tunnel. Inks were exposed to accelerated aging in an accelerated weathering chamber and their physical–chemical properties were investigated. The presence of residual fractions of unreacted species trapped in the 3D network formed during UV curing interferes with the degradation of the main structure during exposure in the weathering chamber. The ink formulations that did not easily absorb UV light increased in gloss and hardness, indicating that residual crosslinking is taking place at the same time that degradation is occurring. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41116.     

PBAT/PLA薄膜的制备及性能研究

将聚乳酸（PLA）和聚对苯二甲酸-己二酸-丁二醇酯（PBAT）共混制备成共混材料,探讨了不同PLA含量对材料性能的影响。结果表明,PBAT/PLA共混材料中,随着PLA含量的增加,拉伸强度先降低后升高,当PLA含量为90 %时,拉伸强度达到60.12 MPa,而其断裂伸长率从703 %降低至8 %,由韧性材料逐渐转变为脆性材料;PLA含量为30 %时,性能变化出现拐点;PLA含量为50 %时出现明显相分离,且PLA的加入可以加速PBAT材料的结晶,使结晶温度由38 ℃提高至82 ℃;PBAT/PLA共混材料在PLA含量低于70 %时,都可以实现较好的吹膜过程,且薄膜材料的拉伸强度为39.59 MPa,断裂伸长率不低于137 %。     

Thermal conductivity of carbon fiber/liquid crystal polymer composites

Thermally conductive resins are needed for bipolar plates in fuel cells. Currently, the materials used for these bipolar plates often contain a single type of graphite in a thermosetting resin. In this study, varying amounts of two different types of polyacrylonitrile based carbon fibers, Fortafil 243 and Panex 30, were added to a thermoplastic matrix (Vectra A950RX Liquid Crystal Polymer). The resulting single filler composites were tested for thermal conductivity and a simple exponential thermal conductivity model was developed for the square root of the product of the in‐plane and through‐plane thermal conductivity . The experiments showed that the through‐plane thermal conductivity was similar for composites up to 40 vol % fiber. However, at higher loadings, the Panex 30 samples exhibited higher thermal conductivity. The experiments also showed that the in‐plane thermal conductivity of composites containing Panex 30 was higher than those containing Fortafil 243 for all volume fractions studied. Finally, the model agreed very well with experimental data covering a large range of filler volume fraction (from 0 to 55 vol % for both single filler systems). The model can be used with existing through‐plane thermal conductivity models to predict in‐plane thermal conductivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5456–5462, 2006     

Synergistic effect of kaolinite/halloysite on the flammability and thermostability of polypropylene

Kaolinite (Kaol) and halloysite nanotubes (HNT) are both aluminosilicate clays with similar chemical formulation and different microshapes. In this article, nanotubular HNT and nanoplate Kaol together were introduced into polypropylene (PP) containing intumescent flame retardant (IFR). The flammability of the PP composites was characterized by limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimeter tests (CCT). The results showed that for the composite with 75 wt % PP and 25 wt % IFR, its LOI was 31.0% and it obtained a UL‐94 grade of V‐2. For the composite of 75 wt % PP, 23.5 wt % IFR, and 1.5 wt % (Kaol/HNT = 9/1), its LOI increased to 36.9 and it obtained a UL‐94 grade of V‐0; at the same time, its peak heat release rate value in CCT decreased by 82.2% compared to neat PP. The thermostability analysis indicated that the mixture of Kaol/HNT could improve the thermostability and final char yield. The char residues were comprehensively analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results illustrated that the Kaol/HNT combination was beneficial to forming a crosslinked network and promoting formation of a compact char with higher strength. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46507.