Characterization of virgin and recycled poly(ethylene terephthalate) (PET) fibers

In this study, we compared the properties of recycled poly(ethylene terephthalate) (PET) fibers and virgin PET fibers. All these experiments present the differences or similarities between them on surface morphology, mechanical properties, and internal fiber structure. The results show that the surface morphology of both PET fibers is similar. According to the tests on mechanical properties, it can be observed that recycled PET fibers have a higher tensile strength and greater elongation at break. The recycled fiber has a higher degree of crystallinity while with the smaller average crystallite size based on the X-ray diffraction data. In polarized attenuated total reflectance infrared technique, the virgin fibers have a better performance than the recycled ones in orientation. Fourier Transform Infrared spectrum analysis indicates that both kinds of fibers have the similar representative groups.     

利用废弃聚酯制品生产纺织纤维

为了深入研究利用废弃聚酯制品制造高质量纺织纤维,从而减少环境污染,促进可持续发展,综述了近年来采用废弃聚酯制品制造纤维的加工技术、国内外研究发展现状,并分析了存在的问题。分析表明,采用化学再生法,可利用废弃聚酯制品制得高质量纺织纤维。并认为今后研究重点应放在聚酯解聚、分离提纯和再聚合纺丝上,以提高再生纤维品质;醇解法和超临界流体法等新型分解提纯方法具有广阔的发展前景。     

Preparation and characterization of electrically semi-conductive polyfuran-coated poly(ethylene terephthalate) fibers

One of the most important textile materials, poly(ethylene terephthalate) (PET) fiber, was coated with a semi-conductive polyfuran (PFu) by in situ oxidative polymerization using FeCl₃ oxidant in solvent mixture of acetonitrile–chloroform. The effects of polymerization conditions such as volume ratios of acetonitrile/chloroform, monomer concentration, and oxidant/monomer mol ratio were investigated on PFu content (%) of the composites. It was observed that pretreatment of PET in dichloromethane increased PFu content and its coating continuity before polymerization. The highest PFu content (12.0%) was obtained using FeCl₃/furan mol ratios of 3.5 in acetonitrile/chloroform mixture (5/1). The density values of the composites with different PFu contents were measured. Composite fibers were also subjected to doping processes with HCl and I₂ vapors, separately, and it was observed that the surface resistivity of PFu/PET (10¹² Ω/cm²) reached to 53 Ω/cm² after doping with I₂. The structural, thermal, and morphological characterization was performed with FTIR, XRD, TGA, and SEM, respectively.     

仿棉共聚酯纤维的制备及其性能表征

普通聚酯纤维吸湿性差,易产生静电现象,染色需要在高温高压条件下进行,为改善聚酯纤维的服用舒适性,在聚酯中引入聚乙二醇柔性链段、季戊四醇、二氧化钛经共聚制备得到多组分改性共聚酯。对纤维形态结构调控,得到截面十字异形仿棉纤维。对仿棉共聚酯纤维的吸湿、抗静电性及染色性进行了测试表征。结果表明,共聚酯具有良好的成纤性、力学性能,制备的短纤维在标准温湿度环境下的回潮率为0.93%,5次洗涤后的比电阻为4.23×108Ω·cm,对气态水具有快吸速干的特点,可实现常压沸染。     

Preparation and characterization of poly(ethylene terephthalate) copolyesters and fibers modified with sodium-5-sulfo-bis-(hydroxyethyl)-isophthalate and poly(ethylene glycol)

New copolyesters were successfully prepared with SIPE and PEG units designated as cationic dyeable polyester and easy cationic dyeable polyester. The number average molecular weight of PEG unit is 6000 (abbreviated as PEG6000). Corresponding copolyesters were spun into fibers with melt spinning method. Chemical and crystalline structures were characterized by the NMR and WAXD measurement, and thermal properties were tested by Differential Scanning Calorimetry and Thermogravimetric Analysis, respectively. NMR experimental results indicated the actual molar ratio of comonomers was basically consistent with the correlative feed ratio. WAXD results showed that crystalline structures of prepared copolyesters were similar to that of Poly(ethylene terephthalate). Moreover, the glass transition temperature, melting temperature, and thermal degradation temperature were found to decrease with the increase in weight ratio of PEG6000 units since the incorporation of higher PEG6000 content brought more ether bonds into molecular chains, which increased the asymmetry and irregularity of molecular chains and led to lower crystallinity. Besides, when content of PEG6000 increased, the breaking tenacity and initial modulus were reduced, yet elongation at break enhanced. It suggested that PEG6000 segments reduced the symmetry of molecular chains and decreased the orientation degree of fibers. In addition, because the incorporation of higher weight percentage of PEG6000 led to more hydroxyl end groups and ether bonds in molecular chains, the moisture regain of fibers increased, manifesting fibers had better hydrophilicity with increasing weight ratio of PEG6000 components.     

再生聚酯/聚丙烯纤维复合板材的制备与研究

以再生聚酯(PET)短纤维和聚丙烯(PP)短纤维为原料,采用针刺法非织造工艺技术制得用于汽车内饰的纤维复合毡,再进行热压成型处理得到纤维复合板材。通过单因子试验研究了原料配比和热压工艺参数对复合板材的拉伸强度和弯曲强度的影响。结果表明:当PET/PP纤维质量混合比为50/50、热压温度为220℃、热压时间为1.5 min、热压压力为4 MPa时,再生PET短纤维/PP短纤维复合板材的力学性能达到最大值。     

Decontamination efficiency of a new post-consumer poly(ethylene terephthalate) (PET) recycling concept

The aim of the study was to investigate and evaluate the cleaning efficiency of a new recycling concept for post-consumer poly(ethylene terephthalate) (PET). The so-called Flake To Resin (FTR®) recycling process produces PET pellets or preforms from conventionally recycled PET flakes for the application in new PET packaging in direct food contact. The investigated process can be considered as ‘super-clean’ recycling process and was developed to introduce conventional recycled post-consumer (PCR) PET flakes up to an amount of 50% into the pellet and preform production. Within the study the cleaning efficiency of the investigated FTR process was determined by a challenge test. The experimental results obtained from three challenge tests with different input concentrations of the surrogates and different amounts of post-consumer PET flakes show that all applied surrogates are very efficiently removed by the investigated recycling process. The cleaning efficiencies for all surrogates are above 99.9%. In the final product of the process no surrogates could be determined above the detection limits (0.5?mg kg^?1) even if the initial concentrations were in the percentage range. From a migrational point the final product, which are either PET pellets or preforms, was similar to virgin PET. Only the PET typical substances acetaldehyde and ethylene glycol had slightly higher concentrations than found in a conventional PET virgin sample used as reference. The generally accepted migration limit of 10?µg kg^?1 for the surrogates in the final products of the challenge tests is established for all kinds of foodstuffs.     

Decontamination efficiency of a new post-consumer poly(ethylene terephthalate) (PET) recycling concept

The aim of the study was to investigate and evaluate the cleaning efficiency of a new recycling concept for post-consumer poly(ethylene terephthalate) (PET). The so-called Flake To Resin (FTR®) recycling process produces PET pellets or preforms from conventionally recycled PET flakes for the application in new PET packaging in direct food contact. The investigated process can be considered as 'super-clean' recycling process and was developed to introduce conventional recycled post-consumer (PCR) PET flakes up to an amount of 50% into the pellet and preform production. Within the study the cleaning efficiency of the investigated FTR process was determined by a challenge test. The experimental results obtained from three challenge tests with different input concentrations of the surrogates and different amounts of post-consumer PET flakes show that all applied surrogates are very efficiently removed by the investigated recycling process. The cleaning efficiencies for all surrogates are above 99.9%. In the final product of the process no surrogates could be determined above the detection limits (0.5 mg kg^-1) even if the initial concentrations were in the percentage range. From a migrational point the final product, which are either PET pellets or preforms, was similar to virgin PET. Only the PET typical substances acetaldehyde and ethylene glycol had slightly higher concentrations than found in a conventional PET virgin sample used as reference. The generally accepted migration limit of 10 µg kg^-1 for the surrogates in the final products of the challenge tests is established for all kinds of foodstuffs.     

不同牵伸倍率下聚酯复合纤维的微观结构与性能

为研究聚对苯二甲酸乙二醇酯/聚对苯二甲酸丙二醇酯(PET/PTT)并列型复合纤维制备工艺与其结构及性能之间的关系,借助二维广角X射线衍射仪、差示扫描量热仪等对未牵伸以及2.35～3.35倍牵伸纤维的结晶取向性能、热性能、力学性能以及卷曲性能进行测试与分析。结果表明：随着牵伸倍率的增加,PET/PTT复合纤维内部单组分结晶度变化有所差异,PET组分结晶度由43.04%增至45.73%,但PTT组分的结晶度几乎不变,其取向度由82.3%增大至89.2%,然后保持稳定,说明牵伸诱导取向达到饱和;同时,取向度的增大也导致PET/PTT复合纤维的弹性模量由16.8 cN/dtex增加到23.1 cN/dtex,断裂强度由2.9 cN/dtex增加到3.5 cN/dtex,但断裂伸长率由52.6%下降到38.6%;牵伸倍率的增加导致双组分纤维结构差异明显,使复合纤维的卷曲性能更加优异。     

Migration measurement and modelling from poly(ethylene terephthalate) (PET) into soft drinks and fruit juices in comparison with food simulants

Poly(ethylene terephthalate) (PET) bottles are widely used for beverages. Knowledge about the migration of organic compounds from the PET bottle wall into contact media is of interest especially when post-consumer recyclates are introduced into new PET bottles. Using migration theory, the migration of a compound can be calculated if the concentration in the bottle wall is known. On the other hand, for any given specific migration limit or maximum target concentration for organic chemical compounds in the bottled foodstuffs, the maximum allowable concentrations in the polymer C _P,0 can be calculated. Since a food simulant cannot exactly simulate the real migration into the foodstuff or beverages, a worse-case simulation behaviour is the intention. However, if the migration calculation should not be too overestimative, the polymer-specific kinetic parameter for migration modelling, the so-called A _P value, should be established appropriately. One objective of the study was the kinetic determination of the specific migration behaviour of low molecular weight compounds such as solvents with relatively high diffusion rates and, therefore, with high migration potential from the PET bottle wall into food simulants in comparison with real beverages. For this purpose, model contaminants were introduced into the bottle wall during pre-form production. The volatile compounds toluene and chlorobenzene were established at concentrations from about 20–30 mg kg^?1 to 300–350 mg kg^?1. Phenyl cyclohexane was present at concentrations of 35, 262 and 782 mg kg^?1, respectively. The low volatile compounds benzophenone and methyl stearate have bottle wall concentrations of about 100 mg kg^?1 in the low spiking level up to about 1000 mg kg^?1 in the highly spiked test bottle. From these experimental data, the polymer specific parameters (A _P values) from mathematical migration modelling were derived. The experimental determined diffusing coefficients were determined, calculated and compared with literature data and an A _P′ value of 1.0 was derived thereof for non-swelling food simulants like 3% acetic acid, 10% ethanol or iso-octane. For more swelling condition, e.g. 95% ethanol as food simulant, an A _P′ value of 3.1 seems to be suitable for migration calculation. In relation to PET recycling safety aspects, maximum concentrations in the bottle wall were established for migrants/contaminants with different molecular weights, which correspond with a migration limit of 10 μg kg^?1. From the experimental data obtained using food simulants and in comparison with beverages, the most appropriate food simulant for PET packed foods with a sufficient but not too overestimative worse-case character was found to be 50% ethanol. In addition, it can be shown that mass transport from PET is generally controlled by the very low diffusion in the polymer and, as a consequence, partitioning coefficients (K _P/F values) of migrants between the polymer material and the foodstuff do not influence the migration levels significantly. An important consequence is that migration levels from PET food-contact materials are largely independent from the nature of the packed food, which on the other hand simplifies exposure estimations from PET.     

部分醇解聚乙烯醇纤维的氢键结构

用不同醇解度的聚乙烯醇进行冻胶纺丝 ,得到了醇解度为 99.5 %、93%、86 %的聚乙烯醇纤维 ,研究了不同醇解度下纤维中的氢键及其对纤维力学性能的影响。结果表明 ,相对较低的醇解度可以有效控制纺丝过程中氢键的形成 ,提高易拉伸性和纤维的力学性能。     

压力对聚对苯二甲酸乙二醇酯熔体剪切黏度的影响

利用毛细管流变仪和反向压力腔附件在毛细管出口压力高于常压条件下,对聚对苯二甲酸乙二醇酯（PET）熔体的剪切粘度变化进行研究,得到了PET剪切黏度分别与毛细管平均压力和剪切速率的依赖关系。结果表明：在恒剪切速率下,PET剪切黏度随着毛细管平均压力的升高而增大,但各剪切速率下增大程度存在差异,在低剪切速率下剪切黏度压力影响更显著;在恒毛细管平均压力下,PET剪切粘度随剪切速率的增大而减小,表现为剪切变稀现象;通过计算得到290℃时PET的恒剪切速率的压力系数约为11.94GPa^-1。     

Recycle PET再生涤纶机织面料的染整工艺探讨

介绍Recycle PET再生涤纶面料在未来的能源利用和循环经济发展中的前景,着重实验并探讨再生涤纶机织面料的前处理和染色工艺,对其前处理精练退浆剂、分散染料等选择提出有效的实验方法,本文提出一些改善再生涤纶面料在染整过程中的染色均匀性、布面平整、批差等问题,为再生涤纶面料的染整开发提供了一定的实践经验。     

聚酯生物加工技术研究进展

为实现生物加工高聚物的功能化和高性能化,需利用生物技术对聚酯进行亲水化处理。为此,综述了聚酯分解菌的选育现状、2种主要分解酶的特征,重点阐述了生物催化对聚酯结构性能影响的评价和分解产物形成的检测,总结了聚酯的生物降解过程,并展望了聚酯生物加工技术的发展方向。认为先进菌种选育、微生物培养和酶工程技术的应用,将有助于得到更高效和更具工业适应性的生物催化剂,形成具有应用价值的聚酯生物加工技术。     

高分子量壳聚糖∕聚氧乙烯复合纳米纤维的制备

利用3%的高分子量壳聚糖（HCS）与聚氧化乙烯（PEO）以3:1的比例溶解在50%的乙酸水溶液中,使用浓度高于临界胶束浓度的不同表面活性剂改善溶液的可纺性,借助静电纺丝技术制备了HCS/PEO复合纳米纤维。采用扫描电子显微镜（SEM）对复合纳米纤维形貌进行表征,采用傅立叶红外光谱（FTIR）方法研究了HCS、PEO及表面活性剂的相互作用,采用单纤维强力仪测试薄膜力学性能的变化,评价使用戊二醛处理后的HCS、PEO复合纳米纤维膜的力学性能。实验结果表明PEO增强了HCS的成纤性。以胶束形式存在的表面活性剂,通过改变混合溶液中分子间的结合方式,降低溶液粘度,提高了可纺性能。戊二醛交联处理提高了复合纤维的强度。特别是阴阳离子混合表面活性剂的使用,纤维形貌最好,强度明显提高。     

碳点对阻燃聚对苯二甲酸乙二醇酯性能的影响

为探究零维碳纳米材料碳点(CDs)对阻燃聚对苯二甲酸乙二醇酯(FRPET)热力学性能、阻燃性能、力学性能及荧光性能的影响,将对PET具有良好阻燃效果的共聚型阻燃剂2-羧乙基苯基次膦酸(CEPPA)与碳点同时采用原位聚合的方式添加到PET基体中,研究碳点添加量对FRPET各项性能的影响规律.通过极限氧指数(LOI值)、垂...     

高分子量聚对苯二甲酸乙二醇酯中低聚物的提取及其表征

为研究高分子量聚对苯二甲酸乙二醇酯（HMW-PET）中低聚物的成分和含量及其对HMW-PET结晶和热学性能的影响,通过萃取法和沉淀法对纤维级PET、液相增黏和固相增黏HMW-PET产品及过程样中的低聚物进行提取,并借助超高效聚合物色谱和差示扫描量热仪对低聚物进行表征。结果表明：沉淀法可快速分离不同工艺产品中的低聚物,得到的低聚物种类较齐全;而萃取法准确性较高,重复提取偏差控制在3% 以内;不同工艺制备的HMW-PET产品低聚物含量存在明显差异;萃取的低聚物在246.6、310.7 ℃附近出现吸热峰,其中环状三聚体含量最高;纤维级PET 及HMW-PET经提取后冷结晶温度均升高,但纤维级PET 熔融焓降低,而HMW-PET熔融焓升高。     

Migration of formaldehyde and acetaldehyde into mineral water in polyethylene terephthalate (PET) bottles

The levels of formaldehyde (FA) and acetaldehyde (AA) in polyethylene terephthalate (PET) bottles and in commercial mineral water are reported. All the water samples bottled in Japan contained detectable levels of FA (10.1-27.9 μg l^-1) and AA (44.3-107.8 μg l^-1). Of 11 European bottled water samples, eight did not contain either FA or AA, while the remaining three had detectable levels of FA (7.4-13.7 μg l^-1) and AA (35.9-46.9 μg l^-1). In three North American bottled water samples, two contained FA (13.6 and 19.5 μg l^-1) and AA (41.4 and 44.8 μg l^-1), and one did not. Regardless of the region of origin, all the sterilized water samples contained FA and AA, whilst in contrast, none of the unsterilized water without carbonate contained FA or AA. Of the carbonated water samples, three contained FA and AA, and one did not. When fortified with FA and AA, the commercial water sample without otherwise detectable FA and AA was able to reduce levels, although the commercial water sample containing FA and AA could not. The presence of bacteria in the commercial water samples was investigated using an ATP-based bioluminescent assay and heterotrophic plate count method. The commercial water without FA and AA contained heterotrophic bacteria, whilst the commercial water with FA and AA did not contain detectable bacteria. It is suggested that in this case both FA and AA migrated from PET materials, but were subsequently decomposed by the heterotrophic bacteria in the unsterilized water.     

European survey on post-consumer poly(ethylene terephthalate) (PET) materials to determine contamination levels and maximum consumer exposure from food packages made from recycled PET.

Typical contamination and the frequency of misuse of poly(ethylene terephthalate) (PET) bottles are crucial parameters in the risk assessment of post-consumer recycled (PCR) PET intended for bottle-to-bottle recycling for direct food contact applications. Owing to the fact that misuse of PET bottles is a rare event, sustainable knowledge about the average concentration of hazardous compounds in PCR PET is accessible only by the screening of large numbers of samples. In order to establish average levels of contaminants in PET source materials for recycling, PET flakes from commercial washing plants (689 samples), reprocessed pellets (38) and super-clean pellets (217) were collected from 12 European countries between 1997 and 2001. Analysis of these materials by headspace gas chromatography revealed average and maximum levels in PCR PET of 18.6 and 86.0 mg kg-1 for acetaldehyde and 2.9 and 20 mg kg-1 for limonene, respectively. Acetaldehyde and limonene are typical compounds derived from PET itself and from prior PET bottle contents (flavouring components), respectively. Maximum levels in PCR PET of real contaminants such as misuse chemicals like solvents ranged from 1.4 to 2.7 mg kg-1, and statistically were shown to result from 0.03 to 0.04% of recollected PET bottles that had been misused. Based on a principal component analysis of the experimental data, the impact of the recollecting system and the European Union Member State where the post-consumer PET bottles had been collected on the nature and extent of adventitious contaminants was not significant. Under consideration of the cleaning efficiency of super-clean processes as well as migration from the bottle wall into food, it can be concluded that the consumer will be exposed at maximum to levels < 50 ng total misuse chemicals day-1. Therefore, PCR PET materials and articles produced by modern superclean technologies can be considered to be safe in direct food applications in the same way as virgin food-grade PET.     

SiO x layer as functional barrier in polyethylene terephthalate (PET) bottles against potential contaminants from post-consumer recycled PET

The barrier effect of a silicon oxide (SiO _x ) coating on the inner surface of PET bottles, in terms of the ability to reduce the migration of post-consumer compounds from the PET bottle wall into food simulants (3% acetic acid and 10% ethanol), was investigated. The barrier effect was examined by artificially introducing model substances (surrogates) into the PET bottle wall to represent a worst-case scenario. Test bottles with three different spiking levels up to ～1000 mg kg^?1 per surrogate were blown and coated on the inner surface. The SiO _x -coated bottles and the non-coated reference bottles were filled with food simulants. From the specific migration of the surrogates with different bottles wall concentrations, the maximum surrogate concentrations in the bottle wall corresponding to migration of 10 µg l^?1 were determined. It was shown that the SiO _x coating layer is an efficient barrier to post-consumer compounds. The maximum bottle wall concentrations of the surrogates corresponding to migration of 10 µg l^?1 were in the range of 200 mg kg^?1 for toluene and ～900 mg kg^?1 for benzophenone. Consequently, the SiO _x coating allows use of conventionally recycled post-consumer PET flakes (without a super-clean recycling process) for packaging aqueous and low alcoholic foodstuffs (under cold-fill conditions) and protects food from migration of unwanted contaminants from post-consumer PET.