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1.
The effect of the mixing condition in a mill‐type mixer on the thermal property and the crystal formation of the poly(l ‐lactide)/poly(d ‐lactide) blends is investigated. The blends melt‐mixed at 200 and 210 °C under application of a high shear flow tend to show a single melting peak of the stereocomplex crystal (SC) in the differential scanning calorimetry first and second heating processes without indicating the trace of the melting of homo‐chiral crystal. The mixing at an elevated temperature causes a serious thermal degradation. Further kneading of the blends at an elevated temperature higher than Tm of SC causes the transesterification between the same enatiomeric chains forming block copolymers of l ‐ and d ‐chains. This block copolymer acts as a nucleating agent of SC and the compatibilizing agent between poly(l ‐lactide) and poly(d ‐lactide) and promotes the formation of SC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45489. 相似文献
2.
Phetdaphat Boonsuk Kaewta Kaewtatip Sirinya Chantarak Antonios Kelarakis Chiraphon Chaibundit 《应用聚合物科学杂志》2018,135(26)
Tough biodegradable films were prepared using a poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP) (1:1) blend with plasticizers of glycerol (GLY), sorbitol (SOR), and their (one to one) mixture. We studied the effect of plasticization on the structural, thermal, and mechanical properties of the PVA/PVP blend films. Fourier transform infrared spectra indicated good miscibility of the two components due to the H‐bonding between the PVA and PVP molecules. The addition of plasticizers reduced the interaction between PVA and PVP, evidenced by an increase in the intensity of PVA diffraction peaks observed in the X‐ray diffraction (XRD) characterization. Thermal degradation of the blends increased as a function of the plasticizer used. GLY affected thermal degradation more than SOR and the mixtures. The incorporation of the plasticizers promoted the growth of PVA crystals as evidenced by XRD patterns and the enthalpy of fusion (ΔHf) obtained by differential scanning calorimetry measurements. The introduction of SOR to the binary blend increased toughness seven times and imparted simultaneous and pronounced improvements to maximum tensile stress and elongation at break. This behavior holds out great promise for the development of a new generation of mechanically robust, yet thoroughly biodegradable materials that could effectively supplant conventional polymers in demanding applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46406. 相似文献
3.
The detail information of both α and β form poly(vinylidene fluoride) (PVDF) crystal effect on the crystallization behavior of poly(butylene succinate) (PBS) were systematically studied. The results show that β form PVDF can obviously improve the melt‐crystallization temperature of PBS during the nonisothermal crystallization process. Both crystallization time span and spherulitic size of PBS decrease with the increasing amount of β form PVDF, which enhances the primary nucleation of PBS. But α form PVDF shows no nucleating effect on PBS crystallization, exhibiting as almost unchanged Tc values for α form PVDF‐blended PBS samples. The intrinsic mechanism for the nucleating effect of β form PVDF on PBS was proposed to be the epitaxial crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40991. 相似文献
4.
The use of latent heat storage materials using phase change materials (PCMs) is an effective way of buffering thermal fluctuations and has the advantages of high‐energy storage density and the isothermal nature of the storage process. The aim of this work was to develop slabs with energy storage capacity for their application in refrigerated foods. To this end, polycaprolactone (PCL) and polystyrene (PS) were used as encapsulating matrices of a PCM, specifically RT5 (a paraffin which has a transition temperature at 5°C), by using electrohydrodynamic processing. The effect of storage temperature (4°C and 25°C) and time on the morphology and thermal characteristics of the PCL/RT5 and PS/RT5 slabs was evaluated. Results showed that RT5 can be properly encapsulated inside both polymers, although PCL provided better encapsulation efficiency. Encapsulation efficiency was affected not only by the polymer matrix but also by storage time at 25°C. The greatest encapsulation efficiency (98.6%) and optimum heat management performance was achieved for PCL/PCM slabs stored at 4°C, corresponding to materials composed of ～44 wt % of PCM (core material) and ～56 wt % of the PCL shell material. These temperature buffering materials can be of great interest to preserve the quality of packaged foods and to increase efficiency and reduce energy consumption in refrigeration equipment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40661. 相似文献
5.
Effects of cyanuric acid (CA) on nonisothermal and isothermal crystallization, melting behavior, and spherulitic morphology of bacterial copolyesters of poly(3‐hydroxybutyrate), i.e., poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH), have been investigated. CA has excellent acceleration effectiveness on the melt crystallization of bacterial PHB, PHBV, and PHBH, better than the nucleating agents reported in the literatures, such as boron nitride, uracil, and orotic acid. PHBV and PHBH do not crystallize upon cooling from the melt at 10°C/min, while they are able to complete crystallization under the same conditions with an addition of 1% CA, with a presence of sharp crystallization exotherm at 75–95°C. Isothermal crystallization kinetics of neat and CA‐containing PHBV and PHBH were analyzed by Avrami model. Crystallization half‐times (t1/2) of PHBV and PHBH decrease dramatically with an addition of CA. The melting behavior of isothermally melt‐crystallized PHBV and PHBH is almost not influenced by CA. Spherulitic numbers of PHBV and PHBH increase and the spherulite sizes reduce with an incorporation of CA. Nucleation densities of PHBV and PHBH increase by 3–4 orders of magnitude with a presence of 1% CA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
6.
Fatemeh Razmjoo Ehsan Sadeghi Milad Rouhi Reza Mohammadi Razieh Noroozi Saeede Safajoo 《应用聚合物科学杂志》2021,138(8):49875
The effects of different percentages of Zedo gum (ZG) (10, 20, and 30 w/w%) on the properties of polyvinyl alcohol (PVA) films by casting method were investigated in this study. Physical, thermal, optical as well as mechanical properties of neat PVA, PVA/ZG and neat ZG films were also characterized. All blend PVA/ZG films produced homogeneous, flexible and transparent films, while neat ZG could not form flexible films and films were opaque. Moreover, Fourier transform infrared (FTIR) spectroscopy and thermal behavior confirmed the formation of hydrogen bonds and subsequently compatibility of the two polymers. In general, reduced moisture content, water solubility and water vapor permeability (WVP) were obtained in the blend films rather than the neat PVA films. However, this reduction tended to increase with a rise in the amount of ZG. Furthermore, films with higher ZG concentration (30%) showed lower mechanical strength than the other blend films but were stronger than neat PVA films. However, low water vapor permeability, high mechanical properties and thermal resistance made this edible film appropriate for packaging different food and non-food applications. 相似文献
7.
In this work, the cure kinetics of a novel acrylated epoxidized hemp oil (AEHO)‐based bioresin was investigated for the first time by differential scanning calorimetry (DSC) using both isothermal and nonisothermal conditions. This new bioresin was synthesized by the acrylation of a previously epoxidized hemp oil (EHO) bioresin. The curing of the AEHO bioresin showed an autocatalytic behavior with the vitrification phenomenon preventing the conversion reaching unity for all the temperatures studied. It was found that the curing behavior can be modeled with high accuracy using a modified Kamal autocatalytic model that takes into account the vitrification phenomenon. Dynamic activation energies were determined from the Kissinger and Ozawa–Flynn–Wall methods, resulting in 58.87 and 62.02 kJmol?1, respectively. In addition, activation energies associated with the autocatalytic model constants, k1 and k2, were established to be equal to 58.94 and 45.32 kJmol?1, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
8.
The crystallization kinetics and spherulitic morphology of six‐armed poly(L‐lactic acid) (6a‐PLLA)/poly(3‐hydroxybutyrate‐co?3‐hydroxyvalerate) (PHBV) crystalline/crystalline partially miscible blends were investigated with differential scanning calorimetry and polarized optical microscopy in this study. Avrami analysis was used to describe the isothermal crystallization process of the neat polymers and their blends. The results suggest that blending had a complex influence on the crystallization rate of the two components during the isothermal crystallization process. Also, the crystallization mechanism of these blends was different from that of the neat polymers. The melting behavior of these blends was also studied after crystallization at various crystallization temperatures. The crystallization of PHBV at 125°C was difficult, so no melting peaks were found. However, it was interesting to find a weak melting peak, which arose from the PHBV component for the 20/80 6a‐PLLA/PHBV blend after crystallization at 125°C, and it is discussed in detail. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42548. 相似文献
9.
Kauê Pelegrini Indianara Donazzolo Vanessa Brambilla Ana Maria Coulon Grisa Diego Piazza Ademir José Zattera Rosmary Nichele Brandalise 《应用聚合物科学杂志》2016,133(15)
Poly(lactic acid) (PLA), the polymer object of this study, degrades by a biotic process after an abiotic hydrolysis process. Its degradation was evaluated after 600 days of exposure in a simulated marine environment (SME), as buriti fiber‐reinforced composites having triacetin as coupling agent. Composites were obtained by extrusion and films were produced by compression molding. After between 60 and 600 days of exposure, PLA had a weight loss of 2.5%, PLA/T of 1.5%, and 10–12% of weight loss for PLA/B and PLA/B/T, respectively. PLA intercalates reduction, increase, and decrease of its crystallinity attributed to hydrolysis (up to 15 days), impairment of amorphous segments (45 days), and loss of integrity of the matrix (100–600 days), respectively. In the PLA/T composites, triacetin inhibited the diatom colonization process, having its crystallinity values increased after nearly 100 days of exposure with subsequent reduction. For samples with buriti fiber, changes in crystallinity were attributed to absorption of water and exposure of matrix amorphous segments. PLA degradation in a SME is evidently favored by the use of natural fibers since they make easier water access to the matrix and colonization by the protists group, diatoms, showing that the polymer can have reduced post‐use shelf life as composites, with benefits while in use and at the same time post‐use environmental benefits. Triacetin inhibits PLA colonization and degradation up to 45 days after exposure, after which it no longer influences the degradation process. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43290. 相似文献
10.
Davi Rabelo de Oliveira Izabel de Menezes Nogueira Francisco Jonas Nogueira Maia Morsyleide Freitas Rosa Selma Elaine Mazzetto Diego Lomonaco 《应用聚合物科学杂志》2017,134(46)
The environmentally friendly esterification of acetosolv lignin (AL), obtained from pressed oil palm mesocarp fibers, is described, for the improvement of thermo‐oxidative properties of poly(methyl methacrylate) (PMMA) films. Acetylation of AL was performed in ecofriendly conditions using acetic anhydride in the absence of catalysts. Acetylated acetosolv lignin (AAL) was successfully obtained in only 12 min with a solvent‐free and catalyst‐free microwave‐assisted procedure. Lignins were characterized by Fourier transform infrared spectroscopy, size exclusion chromatography, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), confirming the efficacy of the methodology employed. AL and AAL as fillers in different concentrations (1% and 5%) were added to PMMA films. The thermal and mechanical properties of the lignin‐incorporated films were analyzed by TGA, DSC, and dynamic mechanical analysis (DMA). The films incorporated with lignin and acetylated lignin presented initial degradation temperature (Tonset) and onset oxidative temperature (OOT) values higher than pure PMMA films, contributing thus to an enhancement of thermo‐oxidative stability of PMMA. The DMA analyses showed that incorporation of AL or AAL increased the storage modulus (E′) of PMMA films, but did not affect their glass‐transition temperatures (Tg). The results indicate the potential use of oil palm mesocarp lignin to enhance the thermo‐oxidative properties of PMMA without compromising its mechanical response. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45498. 相似文献
11.
This paper investigates the effects of natural flours on the crystallization behavior of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH). Two types of PHBH (3‐hydroxyhexanoate [3HH] contents of 5.6 and 11.1 mol %) were used as polymer matrix. One of two natural flours (cellulose or wood) at 1 wt % was added to this PHBH matrix. Crystallization behaviors under nonisothermal conditions were characterized using differential scanning calorimetry (DSC), while those under isothermal conditions were characterized using DSC and polarized optical microscopy. The results suggested that both cellulose and wood flour addition enhanced crystallization of the PHBH containing 5.6 mol % of 3HH (i.e., increased crystallization peak temperature and degree of crystallinity under the nonisothermal conditions, as well as decreased crystallization half time under the isothermal conditions). Of the two flours, wood flour was found to have greater effects, due to its higher crystal nucleating ability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43600. 相似文献
12.
Andrea Todorovic Katharina Resch-Fauster Arunjunai Raj Mahendran Gernot Oreski Wolfgang Kern 《应用聚合物科学杂志》2021,138(16):50239
The effect of the hardener type and amount on the curing reaction and the resulting thermal and mechanical performance characteristics of epoxidized linseed oil are studied in detail. The analysis of the curing mechanism reveals that due to steric hindrance, side reactions and/or fast gelation, the optimal mixing ratio of bio-based epoxy resins and hardeners has to be determined experimentally and cannot be calculated. The investigated thermosets exhibit a glass transition temperature of 12, 54, and 145°C after curing. The overall mechanical performance of the resulting resin ranges from soft and flexible to stiff and rigid, depending on the hardener type applied, which can be utilized in the formation of epoxy composites and coatings. 相似文献
13.
This study introduces a novel biodegradable material produced from processing cellulose and regenerating it in aqueous high-molecular-weight polyethylene oxide (PEO). X-ray diffraction and transmission electron microscopic analysis show that the blend is highly amorphous and contains a networked structure of cellulose with packets of PEO encapsulated within the network. Thermal analysis shows that the water loss from the blend is much slower than that from cotton at temperatures above the boiling point of water, which proves enhanced water absorption and retention properties of the material. It is found that when the material is mixed with sand, up to 1% by weight, the amount of time of water retention in sand increases more than three times. Because of this characteristic, it could be used to improve water storage and availability in sandy soils and to reduce irrigation costs in arid climates. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
14.
Poly(trimethylene terephthalate) (PTT) is a material that has intermediate properties between poly(ethylene terephthalate) (PET) and nylon, and produced by polymerizing bio‐based 1,3‐propanediol and terephthalic acid. In this study, the possibility of replacing existing biaxially oriented PET (OPET) and nylon 6 (ONylon) film with biaxially oriented PTT (OPTT) film is investigated to develop a more environmentally friendly retort pouch. In order to define actual problems in the retort pouch manufacturing process, food process, and distribution process, extensive examinations are conducted to study the degradation of physical properties after the in‐processing and sterilization process, the testing of pinhole resistance caused by stress, and the box level drop test. The results show OPTT film to be a promising alternative for OPET and ONylon film, to a limited extent. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46251. 相似文献
15.
Jennifer Renoux Jagadeesh Dani Catherine Douchain Kalappa Prashantha Patricia Krawczak 《应用聚合物科学杂志》2018,135(27)
This article focuses on the preparation of isolated soy protein plasticized by a glycerol and water mixture/poly[(butylene succinate)‐co‐adipate] blends by an original single step extrusion process. Prepared blends were injection‐molded and characterized for their molecular interaction, morphology, rheological, thermal, dynamic mechanical, and mechanical properties. The comparison of these results with those obtained using a more regular two‐step compounding process validates the technical efficiency of this cost‐effective one‐step approach. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46442. 相似文献
16.
This article reports on the encapsulation of a phase change material (PCM) into a hydrophilic polymer, poly(vinyl alcohol) (PVOH), by means of electrospinning. Different strategies were carried out to improve the thermal buffering capacity and the stability of the developed structures when they were exposed to different relative humidity (RH) conditions. On the one hand, the thermal energy storage capacity of PVOH/PCM structures obtained through emulsion electrospinning was optimized by using different amounts of polyoxyethylene sorbitan monolaureate (Tween 20). Surfactant addition successfully increased the heat storage capacity of the developed structures, reaching an optimum performance at a concentration of 0.32% in weight with respect to the total emulsion weight. However, the hydrophilic nature of the developed structures made them extremely difficult to handle due to swelling with increasing RH. To avoid this issue an additional shell layer of poly(caprolactone) (PCL), was applied by coaxial electrospinning. In this case, the PVOH/PCM ratio (core) was optimized to reach the highest heat storage capacity per gram of sample and, then, a PCL solution was used as a shell material to hydrophobize the structures. The optimized coaxial electrospun structures were able to encapsulate about 82% of PCM. The use of both emulsion and coaxial electrospinning strategies are introduced here for the first time as advanced strategies to overcome application issues such as unintended migration and performance drop in the previously developed monophase materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43903. 相似文献
17.
A novel epoxidized hemp oil (EHO) based bioresin was synthesized by epoxidation in situ with peroxyacetic acid. In this research the cure kinetics of an EHO based bioresin system cured with triethylenetetramine (TETA) was studied by differential scanning calorimetry using both isothermal and nonisothermal data. The results show that the curing behavior can be modeled with a modified Kamal autocatalytic model that accounts for a shift to a diffusion‐controlled reaction postvitrification. The total order of the reaction was found to decrease with an increase in temperature from ～ 5.2 at 110°C to ～ 2.4 at 120°C. Dynamic activation energies were determined from the Kissinger (51.8 kJ/mol) and Ozawa‐Flynn‐Wall (56.3 kJ/mol) methods. Activation energies determined from the autocatalytic method were 139.5 kJ/mol and ?80.5 kJ/mol. The observed negative activation energy is thought to be due to an unidentified competitive reaction that gives rise to the appearance of k2 decreasing with increasing temperature. The agreement of fit of the model predictions with experimental values was satisfactory for all temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
18.
Phetdaphat Boonsuk Apinya Sukolrat Kaewta Kaewtatip Sirinya Chantarak Antonios Kelarakis Chiraphon Chaibundit 《应用聚合物科学杂志》2020,137(26):48848
We report a systematic investigation on the structure–property relationships in glycerol-plasticized poly(vinyl alcohol) (PVA)/cassava starch blends prepared via solution casting. In particular, PVA mixed with native, low-oxidized, high-oxidized, and pregelatinized cassava starches were characterized by means of SEM, XRD, FTIR, thermal analysis and mechanical testing and the immiscible systems were received. Burial tests over a period of several days suggested the preferential degradation of the starch and glycerol component (as indicated by the absence of FTIR signatures of those components) and the amorphous phase of PVA (as indicated by the enhanced crystallinity index of the degraded samples). The rheological properties of the blends seem to dictate their morphological characteristics that, in turn, have a profound impact on their mechanical properties. In that sense, the study highlights promising strategies for the development of a new family of polymeric materials that combine their biodegradable nature within superior mechanical properties. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48848. 相似文献
19.
The increasing use of bio‐sourced and biodegradable polymers such as poly(lactic acid) (PLA) in bottle packaging presents an increasing challenge to the polyethylene terephthalate (PET) recycling process. Despite advanced separation technologies to remove PLA from PET recyclate, PLA may still be found in rPET process streams. This study explores the effects of PLA on the mechanical properties and crystallization behavior of blends of PET containing 0.5–20% PLA produced by injection molding. SEM indicates an immiscible blend of the two polymers and TGA confirms the independent behavior of the two polymers under thermal degradation conditions. Temperature‐modulated DSC studies indicate that adding PLA to PET increases the rigid amorphous fraction of the PET moiety. Critical amounts of PLA induce stress oscillation behavior during mechanical testing. The mechanical behavior of the samples is explained by antagonistic interaction between increased rigid amorphous fraction and decreased fracture strength arising from an increased population of PLA microparticles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44147. 相似文献
20.
A series of novel photocrosslinked biobased shape‐stabilized phase change materials (PCMs) based on octadecanol, eicosanol and docosanol have been prepared by UV technique for the purpose of thermal energy storage applications. Epoxidized soybean oil was reacted with acrylic acid to form acrylated soybean oil (ASO). The structure and composition, cross‐section morphology, thermal stability performances and phase change behaviors of ASO and UV‐cured PCMs were examined by using Attenuated total reflection fourier transform infrared spectroscopy, thermogravimetric analysis system (TGA), scanning electron microscopy, and differential scanning calorimetry. The results indicate that the UV‐cured biobased PCMs possess perfect phase change properties and a suitable working temperature range. The heating process phase change enthalpy is measured between 30 and 68 J/g, and the freezing process phase change enthalpy is found between 18 and 70 J/g. The decomposition of UV‐cured PCMs started at 260 °C and reached a maximum of 430 °C. All the biobased UV‐cured PCMs improved latent heat storage capacity in comparison with the pristine ASO sample. With the obtained results we conclude that, these materials promise a great potential in thermal energy storage applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43757. 相似文献