Synthesis and characterization of novel polyurethanes based on aminolysis of poly(ethylene terephthalate) wastes,and evaluation of their thermal and mechanical properties

BACKGROUND: Much research is currently directed towards recycling post‐consumer poly(ethylene terephthalate) (PET) products for both environmental and economic reasons. Aminolysis of PET wastes using different amines, such as allylamine, morpholine, hydrazine and polyamines, leads to different reaction products as diamides of terephthalic acid, which do not possess any potential for further chemical reactions. In the past, the use of ethanolamine has been investigated for the aminolytic degradation of PET waste in the presence of different simple chemicals such as sodium acetate as catalysts. The product obtained, bis(2‐hydroxyethylene) terephthalamide (BHETA), has potential for further reactions to obtain useful products. Nevertheless, there has been no report on using recycled BHETA from PET to synthesize polyurethanes. RESULTS: In this research the product of aminolysis of PET waste, BHETA, was prepared. Then novel polyurethanes were synthesized based on the BHETA prepared, 1,4‐butanediol, ether‐type polyol and various molar ratios of hexamethylene diisocyanate. To evaluate the effect of BHETA, the properties of the polyurethanes without and with BHETA were compared. Fourier transform infrared spectra, thermal transitions, degradation, swelling ratio and chemical resistance of the synthesized polyurethanes were investigated. Also, the polyurethanes were applied as adhesives on various substrates. Comparison of the maximum bond strength of the synthesized polyurethane to that of commercial adhesives shows an about 2.2‐fold increase. CONCLUSION: It is possible to synthesize new polyurethanes with interesting properties using BHETA as an aminolysis product of PET waste. These kinds of materials have potential for many applications, such as adhesives and coatings. Copyright © 2008 Society of Chemical Industry     

Physical Properties of Plasticized Poly(vinyl chloride) Blended with Poly(methyl methacrylate) Nanoparticles Synthesized by Differential Microemulsion Polymerization

In this work, poly(methyl methacrylate) (PMMA) nanoparticles synthesized by differential micro emulsion polymerization were used to improve the physical properties of plasticized poly(vinyl chloride) (PVC). PVC, plasticizer (40 phr), heat stabilizer (2 phr), and lubricant (0.2 phr) were melt-mixed with varied amount of the PMMA nanoparticles (3, 5, 7, and 9 phr) on a two-roll mill, followed by compression molding. The results showed that the tensile strength, Young's modulus, tear strength, and thermal stability were improved, but the elongation at break deteriorated with increased PMMA content. Moreover, the flammability of the plasticized PVC was not improved by the PMMA nanoparticles.     

Preparation and application of triglyceride plasticizers for poly(vinyl chloride)

A series of triglyceride plasticizers were prepared from glycerol, acetic acid, and benzoic acid through a two‐step reaction to develop potential uses of glycerol. The optimum reaction conditions were determined by the esterification of glycerol and acetic acid to produce glyceryl triacetate. When the molar ratio of glycerol to benzoic acid to acetic acid was 1:1:3.5, a novel plasticizer triglyceride mixture (GTM) was successfully synthesized; it had a good plasticizing effect on poly(vinyl chloride) (PVC). The elongation at break of PVC composites containing 80 phr GTM increased around 350%; the corresponding hardness (Shore D) and tensile strength decreased to around 35 D and 20 MPa, respectively. Moreover, the glass‐transition temperature (T_g) of PVC composites containing 40 phr GTM decreased to around 50°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Migration of Epoxidized Sunflower Oil and Dioctyl Phthalate from Rigid and Plasticized Poly(vinyl chloride)

The aim of this paper is the determination of the specific migration of epoxidized sunflower oil (ESO) from rigid and plasticized poly(vinyl chloride) (PVC) into food simulants. ESO was obtained by epoxidation of commercial sunflower oil and used as a thermal organic co-stabilizer for PVC. For that purpose, rigid and plasticized (0, 15, 30, and 45 wt% of dioctyl phthalate or DOP) PVC films stabilized with ESO in the presence of Zn and Ca stearates were used to perform migration testing in olive oil. The test conditions were 12 d at 20 and 40°C and 2 h at 70°C with and without agitation.

The determination of ESO migration was carried out by gas chromatography-mass spectrometry (GC-MS). ESO was quantified by an external standard addition method, using linoleic acid (C_18:2) as the external standard. The influence of various parameters, such as the agitation and time of contact, the temperature, the presence or the absence of the plasticizer, and the plasticizer concentration, was considered.     

Effects of poly(butylene succinate) and ultrafine wollastonite on the physical properties of plasticized poly(vinyl chloride)

In this study, diisononyl phthalate (DINP), a conventional plasticizer of poly(vinyl chloride) (PVC), was partially replaced by a polymeric plasticizer, poly(butylene succinate) (PBS), in order to reduce the leaching out of low‐molecular‐weight plasticizer from the plasticized PVC. Samples were prepared by melt mixing on a two‐roll mill followed by compression molding into a 3‐mm thick sheet. The DINP/PBS‐plasticized PVC provides a dose‐dependent increase in the tensile properties (tensile strength, Young's modulus, and elongation at break), tear strength, and thermal stability, as compared with the DINP‐plasticized PVC. According to the overall properties, PVC plasticized with 10/30 phr (parts by weight per hundred parts of resin) DINP/PBS was selected for preparing composites with varied loadings of an ultrafine wollastonite (particle size of 1,200 mesh). Their tensile properties, tear strength, thermal stability, and morphology were evaluated and compared with the 40 phr of DINP‐plasticized PVC composites. The results showed an increase in the Young's modulus and thermal stability but a decrease in the tensile strength, elongation at break, and tear strength of either 40 phr of DINP‐ or 10/30 phr of DINP/PBS‐plasticized PVC composites. Therefore, the products may be useful where the dimensional and thermal stability of the plasticized PVC are needed. J. VINYL ADDIT. TECHNOL. 21:220–227, 2015. © 2014 Society of Plastics Engineers     

The effect of low levels of plasticizer on the rheological and mechanical properties of polyvinyl chloride/newsprint-fiber composites

Plasticizers play a key role in the formulation of semirigid and flexible PVC and in determining their physical properties and processability. This study examines the effects of the low phr levels of plasticizer (DOP) on the rheological and mechanical properties of rigid and semi-rigid PVC/newsprint-fiber composites. Mechanical and rheological properties of unfilled PVC compounds and PVC/newsprint-fiber composites at 45 phr were compared over the range of 0 to 15 phr of DOP plasticizer. Analyses of data using SAS procedures of ANOVA were also conducted to discern the effects of concentration of plasticizer on these properties. The following conclusions were reached: (1) DOP was relatively ineffective in improving melt flow index of the composites compared to unfilled PVC. (2) The composites were significantly inferior in tensile strength at yield and stiffer than unfilled PVC. The differences observed were roughly the same over the DOP range studied. (3) Elongation at break and toughness (break energy) were lower for the composites and were essentially independent of DOP level, whereas there was a significant improvement for unfilled PVC over the DOP range studied. (4) Impact strengths of the composites and unfilled PVC were essentially comparable up to about 11.25 phr of DOP. However, at 15 phr DOP, impact strength of the composite was far inferior to that of unfilled PVC. (5) The well-known antiplasticization effect was noted for unfilled PVC, as well as to some extent for the filled PVC.     

Structure and properties of poly(vinyl chloride)/montmorillonite composites produced from plastisols

Poly(vinyl chloride) (PVC)/montmorillonite nanocomposites were prepared from plastisols. The concentrations of plasticizer and montmorillonite were varied. The composites were characterized by both X‐ray diffraction and transmission electron microscopy, which indicated that intercalated nanocomposites were prepared, but that the distribution of clay was not uniform on the nanoscale. Plasticizer migration was found to decrease with increasing concentration of clay and could be reduced by 25% when 3 wt% of Cloisite 30B was added in formulations containing 100 phr (parts by weight per hundred parts of resin) of plasticizer. Montmorillonite was found to reduce the tensile properties of PVC, especially when the plasticizer concentration was low, i.e., 50 phr. J. VINYL ADDIT. TECHNOL., 22:140–145, 2016. © 2014 Society of Plastics Engineers     

Synthesis and characterization of polymeric plasticizer from PET waste and its applications in nitrile rubber and nitrile–PVC blend

Polyethylene terephthalate (PET) waste is not biodegradable; thus, it will create environmental hazards if disposed in landfills. Therefore, the only way of addressing the problem of disposal of post-industrial and post-consumer PET wastes is through recycling. The polyester plasticizer for polyacrylonitrile butadiene rubber (NBR) and polyacrylonitrile butadiene–polyvinylchloride rubber blend (NBR–PVC) was obtained by the depolymerization of PET waste with 2-ethyl-1-hexanol. The PET waste was depolymerized until a polymeric plasticizer with the average molecular weight in the range of 450–900 g/mol was obtained. The polymeric plasticizer was characterized for acid and hydroxyl numbers, viscosity, density, FTIR, NMR and TGA/DTA thermogram. The prepared polymeric plasticizer was used in the preparation of nitrile rubber and nitrile–PVC rubber blend rubber sheets, where these sheets were tested for compatibility, tensile strength, elongation-at-break, hardness and ageing properties. Nitrile rubber and nitrile–PVC blend sheets were also prepared using DOP as a plasticizer and a comparative study with the synthesized polymeric plasticizer was made. It was observed that synthesized polymeric plasticizer provides excellent tensile properties and ageing resistance for high-performance applications as compared to that obtained from DOP. The end uses for nitrile rubber and nitrile–PVC rubber blend compounds are quite diverse, but they can be loosely categorized as being either general performances or higher performance applications. Each of these performance categories requires a different set of considerations in terms of compounding with plasticizers.     

Ester‐amide based on ricinoleic acid as a novel primary plasticizer for poly(vinyl chloride)

Utilization of ricinoleic acid as a raw material for the synthesis of green plasticizer would offer an alternative to the phthalate plasticizers. Ester‐amide of ricinoleic acid was synthesized by a two‐step reaction with dibutyl amine and benzoic acid; and then utilized as primary plasticizer in PVC. Ester‐amide plasticizer was added up to 40 phr in PVC; and the prepared PVC sheets were characterized for mechanical, X‐ray diffraction, thermal, rheological, colorimetric, and exudation properties. Addition of the ester‐amide plasticizer demonstrated good incorporation and plasticizing performance in PVC. Viscosity of PVC decreased with increased addition of ester‐amide plasticizer. The dark color of the synthesized plasticizer could have constraints on its application areas; however, the prepared samples illustrated negligible weight loss in the exudation test, attributed to better compatibility between them brought about by the ester, tertiary amide and polarizable benzene ring in the ester‐amide plasticizer with the C‐Cl polar linkage in PVC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41913.     

Application of new oligomeric plasticizers based on waste poly(ethylene terephthalate) for poly(vinyl chloride) compositions

In this study, chemical recycling products of waste poly(ethylene terephthalate) with oligoesters were used as new plasticizers for poly(vinyl chloride) (PVC). The preparation conditions of the dry blend mixtures of the suspension PVC containing synthesised plasticizers were similar to the conditions of the preparing mixtures with commercial plasticizers. The plasticization efficiency of PVC plasticizers was then examined by analysis of the mechanical, physical and chemical properties, as well as the thermal resistance and migration of plasticizer molecules from polymer matrix. Test results proved that compositions with synthesised oligomeric plasticizers possessed similar or better properties than those containing commercial oligomeric plasticizers and much better properties than those having monomeric plasticizers. Thermal stabilities of the proposed plasticizers were higher than those of the commercial plasticizers either monomeric (bis(2-ethylhexyl)phthalate) or oligomeric, despite the fact that the synthesised oligoesters did not contain any antioxidant. The best properties, especially low volatility, very good mechanical properties, low migration were resulted of the transesterification of the waste PET with oligoesters based on adipic acid, triethylene glycol and 2-ethylhexanol which were selected as plasticizers synthesised on the technical scale. The tested plasticized PVC compositions possessed very good tear resistance, tensile strength, decrease of weight loss after 168 h at 80 °C and low migration. Processing properties of PVC compositions containing these synthesised plasticizers confirmed their effectiveness in these compositions for extrusion process.     

Evaluation of the effects of biobased plasticizers on the thermal and mechanical properties of poly(vinyl chloride)

Blends were prepared of poly(vinyl chloride) (PVC) with four different plasticizers; esters of aconitic, citric, and phthalic acids; and other ingredients used in commercial flexible PVC products. The thermal and mechanical properties of the fresh products and of the products after 6 months of aging were measured. Young's modulus of the PVC blends was reduced about 10‐fold by an increase in the plasticizer level from 15 to 30 phr from the semirigid to the flexible range according to the ASTM classification, but a 40‐phr level was required for PVC to retain its flexibility beyond 6 months. At the 40‐phr level, tributyl aconitate performed better than diisononyl phthalate (DINP) or tributyl citrate, in terms of lowering Young's modulus, both in the fresh materials and those aged for 6 months. The effects of the four plasticizers on the glass‐transition temperature (T_g) were similar, with T_g close to ambient temperature at the 30‐ and 40‐phr levels in freshly prepared samples and at 40–60°C in those aged for 6 months. The thermal stability of the PVC plasticized with DINP was superior among the group. Overall, tributyl aconitate appeared to be a good candidate for use in consumer products where the alleged toxicity of DINP may be an issue. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1366–1373, 2006     

Isothermal and Dynamic Thermogravimetric Degradation of Rigid and Plasticized Poly(Vinyl Chloride)/Poly(Methyl Methacrylate) Blends

The thermal degradation of rigid and plasticized poly(vinyl chloride) (PVC)/poly (methyl methacrylate) (PMMA) blends was investigated by means of isothermal and dynamic thermogravimetric analysis in a flowing atmosphere of air. For that purpose, blends of variable composition from 0 to 100 wt% were prepared in the presence (15, 30 and 50 wt%) and in the absence of di-(2-ethyl hexyl) phthalate (DEHP) as plasticizer. The thermal degradation of the blends was investigated by isothermal thermogravimetry at 180°C during 120 min. It was found that the main processes are the dehydrochlorination of PVC and depolymerization of PMMA. The dynamic thermogravimetric experiments were carried out in the temperature range of 30 ? 550°C. The results showed that the thermal degradation of rigid and plasticized PVC/PMMA blends in this broad range of temperatures is a three-step process and that PMMA exerted a stabilizing effect on the thermal degradation of PVC during the first step by reducing the dehydrochlorination.     

Efficient method for recycling poly(ethylene terephthalate) to poly(butylene terephthalate) using transesterification reaction

A method of recycling postconsumer poly(ethylene terephthalate (PET) using transesterification was studied. Shredded flakes of postconsumer PET waste were transesterified with higher diols, such as 1,4‐butanediol, 1,4‐cyclohexane dimethanol, and 1,6‐hexanediol, to yield copolyesters in the presence of Ti(iPrO)₄ and Sb₂O₃ as catalysts. The extent of the formation of undesirable tetrahydrofuran side products was dependent on the molar ratio of PET to1,4‐butanediol and the time of reflux during transesterification. Quantitative insertion of the butylene moiety into PET could be achieved under appropriate reaction conditions. The mechanical properties of PBT obtained by a transesterification reaction of PET with 1,4‐butanediol were comparable to those of virgin PBT (obtained by direct reaction of dimethyl terephathalate with 1,4‐butanediol). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3720–3729, 2004     

Poly(hexane succinate) plasticizer designed for poly(vinyl chloride) with a high efficiency,nontoxicity, and improved migration resistance

Poly(hexane succinate) (PHS) was designed as an alternative type of polyester plasticizer for the modification of poly(vinyl chloride) (PVC). The plasticizing effect of PHS was studied and compared with the traditional dioctyl phthalate (DOP) plasticizer. The results show that the PVC plasticized by PHS had the lowest tensile strength of 15.3 MPa and the highest elongation at break of 105.1% when 35 phr PHS was added. It also exhibited a lower glass‐transition temperature than PVC plasticized by DOP (PVC–DOP); this could be explained by the improvement of free volume for the amorphous part of PVC enhanced by high‐molecular‐weight PHS. The migration‐resistant properties of PVC–PHS was greatly superior to those of PVC–DOP. All of these results illustrate that PHS had a higher plasticizing efficiency than DOP for PVC. PHS could be used as an alternative plasticizer to remove the potential health risks of phthalates migrating out during applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46388.     

The effect of di-2-ethylhexyl phthalate on the thermo-oxidative ageing of poly(vinyl chloride)/epoxidized natural rubber blends

The effect of di-2-ethylhexyl phthalate (DOP) plasticizer on the degradation behaviour of 50/50 poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend was studied by long-term exposure to ambient conditions (27–30°C) in the laboratory. While the unplasticized blend showed obvious changes in physical properties such as hardening, loss of elasticity and embrittlement, the plasticized blend retained its properties. Thermo-oxidative ageing studies were carried out by evaluating the mechanical properties before and after ageing in an air oven at 80°C for 168 h. The relatively rapid degradation of PVC/ENR blend has been attributed to the high concentration of epoxy groups and the occurrence of ring-opening reactions to form ether crosslinks. It was found that the plasticizer confers adequate stabilization upon the addition of a certain threshold amount. The optimum amount of plasticizer required to adequately stabilize the blend is 20 phr. Above this there is a tendency for plasticizer migration to occur. The use of an antioxidant in conjunction with the plasticizer further stabilizes the blend. The general trend is of decrease in mechanical and physical properties with increase in DOP concentration. In addition, ease of processing also increases as indicated by the torque maxima and minima obtained from the Brabender plastograms.     

Epoxidized rice bran oil (ERBO) as a plasticizer for poly(vinyl chloride) (PVC)

With environmental and toxicity concerns becoming more critical, there are increasing efforts to remove phthalates from polymer compounds around the globe more rapidly. Phthalates can be replaced by natural products; in particular, those obtained from vegetable oils and fats. In the present study, a natural-based plasticizer, synthesized by epoxidation of non-toxic rice bran oil (RBO) with peroxy acid generated in situ has been added to poly(vinyl chloride). The influence of various reaction parameters on epoxidation was studied by investigating the reaction ratio, temperature, reaction time and stirring speed. Epoxidized rice bran oil (ERBO) obtained from an optimized reaction condition was analyzed by iodine number and oxirane content. FTIR was used to analyze epoxy group formation. Product ERBO was obtained with 82 % oxirane conversion within 3 h of reaction period. PVC sheets were formulated using a conventional plasticizer di-(octyl) phthalate and was partially replaced by synthesized ERBO. The effect of ERBO addition was tested by mechanical properties (tensile strength, modulus, elongation-at-break, shore D hardness) and compared with commercially available ESBO (epoxidized soybean oil). ERBO presented fairly good incorporation and plasticizing performance, as demonstrated by the results of mechanical properties, exudation, migration tests, thermal stability by thermogravimetric analysis, T _g values as shown by differential scanning calorimetry, replacing about 60 % of the total plasticizer.     

Aminolytic depolymerization of poly(ethylene terephthalate) waste in a microwave reactor

The aminolytic depolymerization of poly(ethylene terephthalate) (PET) taken from waste soft‐drink bottles, under microwave irradiation, is proposed as a recycling method with possible substantial energy savings. The reaction was carried out with ethanolamine and without the use of any other catalyst in a sealed microwave reactor in which the pressure and temperature were controlled and recorded. Experiments under constant temperature or microwave power were carried out for several time periods. The main product, bis(2‐hydroxyethyl) terephthalamide, was identified from Fourier transform infrared (FTIR) spectra and DSC measurements. It was found that PET depolymerization is favoured by increasing temperature, time and microwave power. The average molecular weight of the PET residues, determined using viscosity measurements, was found to decrease with the percentage of PET degradation, indicating a random chain scission mechanism to some extent. From a simple kinetic model, the activation energy of the reaction was evaluated. Complete depolymerization was found to occur in less than 5 min when the irradiation power applied was 100 W or the temperature was 260 °C. These results support the use of microwave‐assisted aminolytic degradation as a very beneficial method for the recycling of PET wastes. Copyright © 2010 Society of Chemical Industry     

Hydrothermic aging of plasticized poly(vinyl chloride): Its effect on the dielectric,thermal, and mechanical properties

Accelerated hydrolytic aging (according to the NFT 5166 method) was performed on samples of poly(vinyl chloride) (PVC) plasticized with dioctylphthalate (DOP) and dinonyladipate (DNA) at different concentration ratios. The aging test consisted of immersing the samples in boiling water at 100°C. The samples were removed from water regularly, that is, every 2 h, for mechanical, thermal, and dielectric characterizations. Thermograms of PVC plasticized with DOP revealed no migration of the plasticizer independent of the concentration used. Moreover, the thermal stability of the samples was not affected by the hydrothermal aging. However, for PVC samples plasticized with DNA, a small amount of the plasticizer migrated from the polymer matrix with a considerable effect on the thermal stability. In fact, the data indicated a decrease in the decomposition temperature from 275 to 225°C, particularly for samples containing 50% (w/w) DNA immersed up to 10 h. The mechanical results showed that for a plasticizer content greater than 30% (w/w), the strain at break obtained for samples plasticized with DNA was lower than that for samples plasticized with DOP because the DNA molecules were more likely to be removed by water on account of their polarity and dimension. Finally, the dielectric measurements showed that the permittivity of all the PVC samples plasticized with DOP and immersed in boiling water was higher than that of the virgin samples. On the contrary, the permittivity of the aged unplasticized PVC was less than that of the nonimmersed samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3447–3457, 2003     

Poly(diethylene glycol adipate): A Study of Its Behavior as a PVC Plasticizer

The compatibility of PVC with poly(diethylene glycol adipate) M _n = 1500 was evaluated by DSC, indicating a limit value of 15 phr. The behavior of the oligomer as a PVC plasticizer, alone or in combination with dioctylphthalate (DOP), was investigated by measurements such as hardness, glass transition temperature, heat stability, and solvent resistance. In spite of its limited compatibility the oligoester can act as a secondary plasticizer enhancing the overall performance of the compositions.     

A new biobased plasticizer for poly(vinyl chloride) based on epoxidized cottonseed oil

The use of epoxidized cottonseed oil as plasticizer for poly(vinyl chloride) was studied. The plasticizer content was set to 70 phr and the optimum isothermal curing conditions were studied in the temperature range comprised between 160 and 220 °C with varying curing times in the 7.5–17.5 min range. The influence of the curing conditions on overall performance of cured plastisols was followed by the evolution of mechanical properties (tensile tests with measurements of tensile strength, elongation at break, and modulus), change in color, surface changes of fractured samples by scanning electron microscopy (SEM), thermal transitions by differential scanning calorimetry, and migration in n‐hexane. The optimum mechanical features of cured plastisols are obtained for curing temperatures in the 190–220 °C range. For these curing conditions, fractography analysis by SEM gives evidences of full curing process as no PVC particles and free plasticizer can be found. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43642.