Synthesis and application of a natural plasticizer based on cardanol for poly(vinyl chloride)

A natural plasticizer with multifunctional groups, similar in structure to phthalates, cardanol derivatives glycidyl ether (CGE) was synthesized from cardanol by a two‐step modification process and characterized by FT‐IR, ¹HNMR, and ¹³CNMR. The resulting product was incorporated to PVC (CGE/PVC), and plasticizing effect was compared with PVC incorporated with two kinds of commercial phthalate ester plasticizers bis (2‐ethylhexyl) benzene‐1,4‐dicarboxylate (DOTP) and diisononyl phthalate (DINP). Dynamic mechanical analysis and mechanical properties testing of the plasticized PVC samples were performed in order to evaluate their flexibility, compatibility, and plasticizing efficiency. SEM was employed to produce fractured surface morphology. Thermogravimetric analysis and discoloration tests were used to characterize the thermal stabilities. Dynamic stability analysis was used to test the processability of formulations. Compared with DOTP and DINP plasticized samples, CGE/PVC has a maximum decrease of 9.27% in glass transition temperature (T_g), a maximum increase of 17.6% in the elongation at break, and a maximum increase of 31.59°C and 25.31 min in 50% weight loss (T50) and dynamic stability time, respectively. The obtained CGE also has slightly lower volatility resistance and higher exudation resistance than that of DOTP and DINP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42465.     

Formulation and properties' evaluation of PVC/(dioctyl phthalate)/(epoxidized rubber seed oil) plastigels

Epoxidized rubber seed oil (4.5% oxirane content, ERSO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. The thermal behavior of the ERSO was determined by differential scanning calorimetry. The effect of the epoxidized oil on the thermal stability of poly (vinyl chloride) (PVC) plastigels, formulated to contain dioctyl phthalate (DOP) plasticizer and various amounts of the epoxidized oil, was evaluated by using discoloration indices of the polymer samples degraded at 160°C for 30 min and thermogravimetry at a constant heating rate of 10°C/min up to 600°C. The thermal behavior of the ERSO was characterized by endothermic peaks at about 150°C, which were attributed to the formation of network structures via epoxide groups, and at temperatures above 300°C, which were due to the decomposition of the material. Up to 50% of the DOP plasticizer in the PVC plastisol formulation could be substituted by ERSO without a marked deleterious effect on the consistency of the plastigel formed. In the presence of the epoxidized oil, PVC plastigel samples showed a marked reduction in discoloration and the number of conjugated double bonds, as well as high temperatures for the attainment of specific extents of degradation. These results showed that the ERSO retarded/inhibited thermal dehydrochlorination and the formation of long (n > 6) polyene sequences in PVC plastigels. The plasticizer efficiency/permanence of ERSO in PVC/DOP plastigels was evaluated from mechanical properties' measurements, leaching/migration tests, and water vapor permeability studies. The results showed that a large proportion of DOP could be substituted by ERSO in a PVC plastisol formulation without deleterious effects on the properties of the plastigels. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

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.     

Characterization of PVC cable insulation materials and products obtained after removal of additives

Organic solvents cyclohexane, dichloromethane, hexane, and tetrahydrofuran were tested to separate the dioctylphthalate (DOP) as plasticizer from the poly(vinyl chloride) (PVC)‐based materials. It was found that the efficiency of ultrasound‐enhanced hexane extraction of the DOP from PVC is 70% and the efficiency of the separation of the DOP and other compounds from the PVC by dissolution in THF followed by subsequent precipitation was 98–99%. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to characterize the thermal behavior of PVC materials before and after extraction of plasticizers. It was found that during heating in the range 20–800°C the total mass loss measured for the nontreated, extracted, and precipitated PVC samples was 71.6, 66.6, and 97%, respectively. In the temperature range 200–340°C, the release of DOP, HCl, and CO₂ was observed by simultaneous thermogravimetry (TG)/FTIR. The effect of plasticizers on thermal behavior of PVC‐based insulation material was characterized by DSC in the range ?40–140°C. It was found that, concerning the PVC cable insulation material before treatment, the value of the glass transition temperature (T_g) was 1.4°C, whereas for the PVC sample extracted by hexane, the value of T_g was 39.5°C and for the PVC dissolved in THF and subsequently precipitated, the value of T_g was 80.4°C. Moreover, the PVC samples after extraction of plasticizers, fillers, and other agents were tested to characterize their thermal degradation. The TG and FTIR results of chemically nontreated, extracted, and precipitated samples were compared. The release of DOP, HCl, CO₂, and benzene was studied during thermal degradation of the samples by FTIR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 788–795, 2006     

Migration of phthalate and non‐phthalate plasticizers out of plasticized PVC films into air

The aim of the present work is to provide information about the migration of phthalate and non‐phthalate plasticizers generally used in flexible polyvinyl chloride (PVC) applications. Plastisols (pastes) were prepared by mixing PVC, plasticizer, and thermal stabilizer. The plasticized PVC (p‐PVC) films are obtained by gelation at 160°C for 15 min. The p‐PVC films were heat treated at 50, 85, 100, 130, and 160°C up to 420 min to follow the mass loss to find out diffusivity of plasticizer out of films into air and to determine related activation energies. The films having di‐octyl terephthalate (DOTP) and di‐isononyl 1,2‐cyclohexanedicarboxylic acid (DINCH) exhibited the lowest mass loss in general, among the phthalate and non‐phthalate plasticizer having p‐PVC films, respectively, as confirmed by FTIR investigation. The same tendency was observed for diffusion coefficients and for the activation energies of migration. The diffusion coefficients were found to be around 3.5 × 10^?18–2.1 × 10^?17 m²/sec for the studied plasticizers in PVC at 50°C and around 4.0 × 10^?15–9.9 × 10^?14 m²/sec at 160°C. The activation energies for 85–160°C interval were determined to be between 70 and 153 kJ/mol (0.72–1.58 eV) for the plasticizers used herein those could be treated as a homologous series as deduced from the related compensation factors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Epoxidation of modified natural plasticizer obtained from rice fatty acids and application on polyvinylchloride films

In recent years, much research effort has been driven to develop alternative plasticizers for medical and commodity plastic materials. In this study, a modified natural plasticizer, synthesized by esterification of rice fatty acids, was modified by epoxidation with peroxy acid generated in situ. Two natural epoxidized plasticizers were obtained, using peracetic acid (NP‐Ac) and peroctanoic acid (NP‐Oc) as reagent. PVC films after addition of these natural epoxidized plasticizers presented fairly good incorporation and plasticizing performance, as demonstrated by results of mechanical properties, T_g values (as shown by DSC), optical microscopy, exudation, and migration tests, FTIR and X‐ray diffraction obtained for plasticized PVC films. NP‐Ac plasticizer presented enhanced plasticizing performance compared with NP‐Oc, probably due to a higher epoxidation degree obtained in the reaction with peracetic acid. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Epoxidized castor oil-based diglycidyl-phthalate plasticizer: Synthesis and thermal stabilizing effects on poly(vinyl chloride)

Epoxidized castor oil-based diglycidyl-phthalate (ECODP) was synthesized and incorporated into poly(vinyl chloride) (PVC) for the first time. The chemical structure of the ECODP was confirmed. The plasticizing effects of ECODP as a replacement for commercial plasticizer dioctyl phthalate (DOP) were investigated. The thermal stability and mechanical properties of PVC films before and after aging were investigated using thermogravimetric analysis (TGA), TGA-FTIR analysis, dynamic mechanical analysis (DMA), and tensile tests. The results indicated that PVC films plasticized with ECODP significantly improved thermal stability, compatibility, and flexibility. When DOP was substituted with ECODP completely, the initial decomposition temperature, 5, 10, 50, and 70% mass loss temperatures (T_i, T₅, T₁₀, T₅₀, and T₇₀) increased by 24.7, 38.9, 32.0, 30.3, and 102.7 °C, respectively. The functional mechanism of the ECODP as a thermal stabilizing plasticizer and the plasticization mechanism of PVC composites were also investigated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47142.     

Plasticizers derived from cardanol: synthesis and plasticization properties for polyvinyl chloride(PVC)

Two natural plasticizers derived from cardanol (CD), cardanol acetate (CA) and epoxidized cardanol acetate (ECA), were synthesized and characterized by ¹H NMR and ¹³C NMR. The plasticizing effects of the obtained plasticizers on semi-rigid polyvinylchloride (PVC) formulations were also investigated. Two commercial phthalate ester plasticizers, dioctyl terephthalate (DOTP) and diisononyl phthalate (DINP), were used as controls. Mechanical and thermal properties, compatibility, thermal stability, microstructure, and workability were assessed by dynamic mechanical analysis (DMA), mechanical analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic stability analysis, respectively. Results indicated that the natural plasticizer ECA had overallsuperior flexibility, compatibility, thermal stability, and workability comparable to both controls. The obtained CA and ECA have lower volatility resistance and similar extraction and exudation resistance than that of DOTP and DINP. The CA was further blended with DOTP in soft PVC films. Results of DMA, TGA and mechanicalanalysis indicated that CA can serve as a secondary plasticizer to improve the related properties of soft PVC formulations. These CD derived plasticizers show promise as an alternative to fully or partially replace petroleum-based plasticizers.     

Novel branched poly(ɛ‐caprolactone) as a nonmigrating plasticizer in flexible PVC: Synthesis and characterization

A series of hyperbranched poly(?‐caprolactone) (HPCLs, denoted as D_X) with different molecular weights were synthesized by the copolymerization of GPCL (PCL initiated by glycidol) and succinic anhydride. The chemical structure of D_X was characterized by ¹H‐NMR gel permeation chromatography and inherent viscosity, and D_X was used as the plasticizer for poly(vinyl chloride) (PVC) compared to traditional plasticizer di‐(ethylhexyl) phthalate (DEHP). The thermal properties, morphology, mechanical properties, and migration stabilities of PVC films were explored with differential scanning calorimetry, thermogravimetric analysis, scanning electron microscope, tensile, and migration tests. PVC/D₁ exhibited the best plasticization efficiency up to 107%, with enhanced tensile strength (18.5 MPa) and ultimate elongation (416%) compared to PVC/DEHP (11.5 MPa and 375%, respectively). PVC/D₁ exhibited remarkably high plasticization efficiency as compared to PVC/DEHP at a plasticizer concentration of PVC below 40 wt %. Moreover, the migration test for PVC/D_X films exhibited minimal plasticizers migration even at very harsh conditions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46542.     

Study on ionic liquid [bmim]PF<Subscript>6</Subscript> and [hmim]PF<Subscript>6</Subscript> as plasticizer for PVC paste resin

Two kinds of room temperature ionic liquids, [bmim]PF₆ (1-butyl-3-methylimidazolium hexafluorophosphate) and [hmim]PF₆ (1-hexyl-3-methylimidazolium hexafluorophosphate), were respectively used as plasticizer for PVC paste resin. The mechanical properties, thermal and ultraviolet ray stabilities, and migration characteristics of the PVC paste resin samples were determined by universal testing machine, TG/DTA, and HPLC. The results showed that the tensile strength and elastic modulus decreased, the elongation at break and thermal stability of PVC paste resin membranes were improved with the increasing of [bmim]PF₆ or [hmim]PF₆ dosages. The immersed time and temperature could accelerate leaching and migration of plasticizers in plasticized PVC paste resin films. Moreover, the effect of solvent environment on migration amount was also studied.     

Sustainable synthesis of bio‐based hyperbranched ester and its application for preparing soft polyvinyl chloride materials

In this study, bio‐based hyperbranched ester was synthesized from castor oil. The chemical structure of the bio‐based hyperbranched ester obtained was characterized with Fourier transform infrared and ¹H NMR spectra. Soft polyvinyl chloride (PVC) materials were prepared via thermoplastic blending at 160 °C using bio‐based hyperbranched ester as plasticizer. The performances including the thermal stability, glass transition temperature (T_g), crystallinity, tensile properties, solvent extraction resistance and volatility resistance of soft PVC materials incorporating bio‐based hyperbranched ester were investigated and compared with the traditional plasticizer dioctyl phthalate (DOP). The results showed that bio‐based hyperbranched ester enhanced the thermal stability of the PVC materials. The T_g of PVC incorporating bio‐based hyperbranched ester was 23 °C, lower than that of PVC/DOP materials at 28 °C. Bio‐based hyperbranched ester showed a better plasticizing effect, solvent extraction resistance and volatility resistance than DOP. The plasticizing mechanism is also discussed. © 2018 Society of Chemical Industry     

Effect of ketal group in castor oil acid-based plasticizer on the properties of poly(vinyl chloride)

Two castor oil acid esters containing a ketal or ketone group (KCL or CL), as alternative plasticizers for poly(vinyl chloride) (PVC), were prepared. The structures were confirmed by ¹H NMR and FTIR spectroscopies. The effects of the presence of a ketal or ketone group in these compounds on PVC plasticization were examined. The DMA and SEM results showed that both plasticizers were miscible with PVC and exhibited excellent plasticizing properties, compared to those of dioctyl phthalate (DOP). The PVC plasticized by KCL displayed a lower T_g value of 20.6 ° C, which was lower than that of PVC plasticized with DOP (22.3 ° C) and PVC plasticized with CL (40.5 ° C). Tensile tests indicated that PVC plasticized using KCL showed a 37% higher of elongation at break than PVC plasticized by CL and 30% higher than PVC plasticized by DOP. The plasticizing mechanism was also investigated. Moreover, exudation, volatility, and extraction tests, along with TGA indicated that the presence of ketal groups effectively improved the migration resistance of plasticizer and the thermal stability of PVC blends. Taken together, introducing ketal groups into plasticizer might be an effective strategy for improving its plasticizing efficiency.     

The Effect of Epoxidized Sunflower Oil on the Miscibility of Plasticized PVC/NBR Blends

Blends of plasticized poly(vinyl chloride) (PVC) with several ratios of nitrile rubber (NBR) were studied. The effects of epoxidized sunflower oil (ESO) in combination with di-(2-ethylhexyl)phthalate (DEHP) in the PVC blends on the tensile strength, elongation, hardness, and dynamical mechanical analysis (DMA) were studied. The modulus and hardness results revealed that the addition of ESO to the blend favors the miscibility of PVC and NBR. The PVC/NBR/(DEHP-ESO) blends behave as a compatible system as is evident from the single T _g observed in DMA. The moderate level broadening of the T _g zone in blends is due to the presence of ESO in the plasticizer system. Blends of plasticized PVC and nitrile rubber showed promising properties. The ESO is suitable to partially replace DEHP in PVC/NBR blends.     

Synthesis of a bio-based plasticizer from vanillic acid and its effects on poly(vinyl chloride)

A new bio-based plasticizer, VA8-8, was prepared derived from vanillic acid, and its structure was verified by nuclear magnetic resonance. It was incorporated into poly(vinyl chloride) (PVC) to replace dioctyl phthalate (DOP), and its plasticizing performance was evaluated. The results indicated that VA8-8 shows good compatible with PVC resin, and has a excellent plasticizing effect for PVC. When DOP was partially or completely substituted with VA8-8, the T_g value PVC blends dropped from 34.6 to 24.3°C and the elongation at break increased from 196.4% to 301.9%, suggesting the enhanced plasticizing efficiency of plasticizer. The plasticizing mechanism was also simulated, and the interactions between VA8-8 and PVC molecules were discussed. The thermogravimetric analysis showed VA8-8 can more effectively improve the thermal stability of PVC than DOP. In addition, the migration resistance of VA8-8 was generally superior to that of DOP. Therefore, VA8-8 is a comparable to or better plasticizer than DOP, and it is a promising alternative plasticizer for PVC.     

Soil burial degradation of new bio‐based additives. Part II. plasticized poly(vinyl chloride) films

Commercial sunflower oil was epoxidized, and the epoxidized oil (ESO) was used as a new thermal stabilizer for poly(vinyl chloride) (PVC). Plasticized formulations stabilized with ESO and epoxidized soya bean oil as a commercial stabilizer were evaluated for comparison. Two plasticizers were used, dioctyl phthalate and diisononyl adipate. The aging of the PVC samples was investigated in landfill soil for 24 months. The modifications of the structure of the polymer were followed by Fourier, transform infrared spectroscopy. Furthermore, the variations of density and mechanical properties (tensile and Shore D hardness) were considered, and the variations of the mass of the samples, the glass transition temperature (T_g), the molar mass distribution, and the weight loss were followed as a function of duration of soil burial. The morphological changes were tracked by scanning electron microscopy. Results showed that the nature of the plasticizer and heat stabilizer affects the properties of PVC as well as the phenomena of migration and biodegradation. J. VINYL ADDIT. TECHNOL., 19:183‐191, 2013. © 2013 Society of Plastics Engineers     

Evaluation effects of biobased plasticizer on the thermal,mechanical, dynamical mechanical properties,and permanence of plasticized PVC

Sunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly in polymeric formulations, especially for poly (vinyl chloride) (PVC). Epoxidized sunflower oil (ESO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. Epoxidation was confirmed using spectroscopic and titration methods. ESO was used as a coplasticizer in PVC for the partial replacement of di‐(2‐ethyl hexyl) phthalate (DEHP). The effect of ESO on the thermal stability of plasticized PVC was evaluated by using synmero scale for the sheets. In presence of ESO plasticized PVC samples showed a reduction in discoloration and the number of conjugated double bonds. By using thermogravimetry, the incorporation of 15/45 of ESO/DEHP in PVC presents the lowest weight loss. The results of the shore hardness and mechanical properties showed that a proportion of DEHP could be substituted by ESO. By use of DMA, the formulation which contains 25 % wt of ESO in plasticizer system shifts the glass transition temperature (T_g) to ambient temperature. The migration phenomenon was studied on PVC based samples plasticized with DEHP and ESO in varying amounts. The migration was monitored by the weight loss percentage of the samples immersed into n‐hexane or heated in an oven. The amount of extracted or volatilized DEHP is proportional to the added ratio of ESO in plasticizer system. All of this favored the partial replacement of DEHP by ESO as biobased plasticizer for flexible PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of hydrothermal ageing on the thermal behaviour of poly(vinyl chloride) filled with wood flour

The hydrothermal ageing of wood‐flour‐filled PVC produced by dry‐blending in a high‐speed mixer in the presence of a plasticizer and other processing additives was carried out to investigate its thermal behaviour, and the results obtained were compared with those for the unfilled material. The dry‐blended compounds were prepared as films by a calendering process. The accelerated hydrothermal ageing was carried out by immersing the samples in boiling water at 100 °C for 110 h. The thermal behaviour of the reference and the aged samples in water was characterized by differential scanning calorimetry (DSC) and determination of the weight changes. The study has shown that during hydrothermal ageing, the samples from the whole formulations absorbed water, for instance, for 30 wt% filled PVC (F30), 16 wt% of water absorption was obtained, while this was only 2.2 wt% for unfilled PVC (F0). It was also noticed that the formulations filled with wood flour up to 10 wt% exhibited similar water absorption kinetics, i.e. the water was mostly absorbed during the first 50 h and the amount absorbed was less than 5 wt%. On the other hand, the 30 wt% filled samples regularly absorbed water up to almost 16 wt% after 100 h of immersion. The DSC data showed that hydrothermal ageing significantly affected the onset temperature of decomposition (T_d) of the unfilled samples by decreasing this temperature from 228 to 215 °C. For the 30 wt% filled samples, only additive migration was observed, while the T_d remained almost unchanged. Furthermore, from the DSC data, processability of the 30 wt% filled PVC samples at elevated temperatures, i.e. 180 to 200 °C was shown. Copyright © 2004 Society of Chemical Industry     

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.     

Synthesis and evaluation of dialkyl furan-2,5-dicarboxylates as plasticizers for PVC

Di(2-ethylhexyl), di(2-octyl), dihexyl, and dibutyl furan-2,5-dicarboxylate were synthesized from furfural and characterized for their plasticizing abilities toward PVC by dynamic mechanical thermal analysis (DMTA) with di(2-ethylhexyl) phthalate (DOP) as the standard of reference. DMTA gave values for the depression of the glass transition temperature (T_g) per mass fraction of plasticizer, and it also yielded a set of parameters, relative to those for DOP, which describe the compatibility of the furan diesters with PVC. The efficiency in lowering T_g as exhibited by di(2-ethylhexyl) furan-2,5-dicarboxylate is similar to that of its benzenoid analog, DOP, and was determined at 2.41 and 2.45°C per mass % plasticizer, respectively. All four furan diesters were found to be more compatible toward PVC than toward DOP, with dibutyl furan-2,5-dicarboxylate the most highly compatible. © 1994 John Wiley & Sons, Inc.     

Preparation of epoxidized cardanol butyl ether as a novel renewable plasticizer and its application for poly(vinyl chloride)

A new type of plasticizer, epoxidized cardanol butyl ether (ECBE), was synthesized via etherification and epoxidation. Successful synthesis was confirmed from Fourier transform infrared, ¹H NMR and ¹³C NMR spectra. The obtained product was evaluated by adding it to poly(vinyl chloride) (PVC) incorporated with dioctyl phthalate (DOP). Mechanical and thermal properties of PVC blends were studied using tensile testing, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Processability, migration and volatility of plasticizing systems were also investigated. Tensile tests found a maximum increase of 17.8% in elongation at break. DMA results indicated that glass transition temperature shifted to lower temperature with a maximum decrease of 5.76 °C. TGA results revealed that PVC blends with higher content of ECBE had higher thermal stability; initial degradation temperature, 50% weight loss temperature and the first peak degradation temperature increased by 15.3, 14.8 and 4.1 °C, respectively. Processing time was extended from 11.56 to 59.94 min. The plasticizing performance of migration and volatility resistance were higher than those of neat DOP. © 2016 Society of Chemical Industry