Reactive Blending Research Articles

Reactive Blending of Recycled Poly(ethylene terephthalate)/Recycled Polypropylene: Kinetics Modeling of Non-Isothermal Crystallization.

Plastics were developed to change our world for the better. However, plastic pollution has become a serious global environmental crisis. Thermoplastic polyesters and polyolefins are among the most abundant plastic waste. This work presents an in-depth non-isothermal crystallization kinetics analysis of recycled post-consumer poly(ethylene terephthalate) (rPET) and recycled polypropylene (rPP) blends prepared through reactive compounding. The effect of pyromellitic dianhydride (PMDA) on crystallization kinetics and phase morphology of rPET/rPP blends was investigated by differential scanning calorimetry (DSC) and microscopy techniques. DSC results showed that increasing rPP content accelerated rPET crystallization while reducing crystallinity, which indicates the nucleation effect of the rPP phase in blends. Further, it was found that the incorporation of PMDA increased the degree of crystallinity during non-isothermal crystallization, even though the rate of crystallinity decreased slightly due to its restriction effects. The non-isothermal crystallization kinetics was analyzed based on the theoretical models developed by Jeziorny, Ozawa, Mo, and Tobin. The activation energy of the crystallization process derived from Kissinger, Takhor, and Augis-Bennett models was found to increase in rPET/rPP blends with increasing PMDA due to hindered dynamics of the system. Rheological measurements revealed that rPET melt viscosity is remarkably increased in the presence of PMDA and reactive blending with rPP relevant for processing. Moreover, nanomechanical mapping of the rPP phase dispersed in the rPET matrix demonstrated the broadening of the interfacial domains after reactive blending due to the branching effect of PMDA. Findings from this study are essential for the recycling/upcycling thermoplastics through non-isothermal fabrication processes, such as extrusion and injection molding, to mitigate the lack of sorting options.

Crystallization behavior analysis and reducing thermal shrinkage of poly(lactic acid) miscibilized with poly(butylene succinate) film for food packaging

AbstractPoly(lactic acid) (PLA) incorporated with poly(butylene succinate) (PBS) through in situ reactive blending is proposed to retard thermal shrinkage. Succinic anhydride (SA) with varied contents (0.01–0.5 phr) was used as a reactive compatibilizer to enhance miscibility between PLA and PBS phases. The success of PLA chemically bound with PBS chains through simple esterification to form PLA‐SA‐PBS phase is confirmed and quantified using an X‐ray photoelectron spectroscopy technique. The binding energy intensity ratio of ester and hydrocarbon in the PLA/PBS/SA blend with 0.5 phr SA increases for two‐fold, as compared to the PLA/PBS blend. The good interfacial adhesion of PLA and PBS phases is achievable with SA content up to 0.1 phr. In addition, the PLA‐SA‐PBS molecules preferentially support crystallization of PBS phase with increased degree of crystallinity (Xc,PBS) by ~15%. These enhanced homogeneity of PLA/PBS/SA blend and high Xc,PBS trigger the increased tensile strength to 50 MPa, and substantially reduced oxygen permeation coefficient approximately 10 times. Remarkably, the interpenetration of PLA‐SA‐PBS phase in amorphous PLA region coexisting with uniformly dispersed PBS crystals inhibits the PLA chain relaxation and deformation at elevated temperatures, leading to maintaining dimensional stability of PLA/PBS/SA films without shrinkage at 100°C.

Quasi block copolymers noncovalent bonded by stereocomplex crystals

Self-assembly of block copolymers (BCPs) yields unparalleled opportunities to integrate exquisite characteristics for preparation of advanced nanotechnology materials. The high-yield manufacturing of BCP is extremely desired, yet rarely exploited. Herein, we displayed that stereocomplex crystals (sc) of poly lactide (PLA) enantiomers, acting as pseudo linkage between adjacent polymer chains, enable formation of quasi-block copolymer (qBCPs) by straightforward melt compounding. Identical content of poly (D-lactide) (PDLA) and poly (L-lactide) (PLLA) were pre-grafted onto the backbones of poly styrene (PS) and poly (methyl methacrylate) (PMMA), respectively. Due to the complementary multiple hydrobonding interactions between PDLA and PLLA grafted moieties, PS-“block”-PMMA connected by cocrystallized sc was induced during the subsequent melt processing of PDLA-g-PS/PLLA-g-PMMA, thus allowing local segregation of PS-“block” and PMMA-“block” with nanometer size. The refined morphology, which was resembled with micro-phase separation of classical BCP, can be facilely tuned by varying the length and ratio of enantiomeric PDLA/PLLA grafts. More interestingly, the PS-“block”-PMMA typed qBCPs demonstrated superiority in compatibilizing immiscible PS/PMMA polymer blends, as compared with the classical compatibilizer (PS-block-PMMA) via reactive blending. Overall, our strategy represents a general method to construct noncovalent linked di-block copolymer via industrially relevant melt processing, which is quite challenging to achieve by existing synthetic technologies.

Tough and Thermostable Polybutylene Terephthalate (PBT)/Vitrimer Blend with Enhanced Interfacial Compatibility.

Polymer blending is an efficient way to obtain extraordinary polymeric materials. However, once permanently cross-linked thermosets are involved in blending, there are challenges in designing and optimizing the structures and interfacial compatibility of blends. Vitrimer with dynamic covalent polymer networks provides an innovative opportunity for blending thermoplastics and thermosets. Herein, a reactive blending strategy is proposed to develop thermoplastic-thermoset blend with enhanced compatibility on the basis of dynamic covalent chemistry. Specifically, polybutylene terephthalate (PBT) and polymerized epoxy vitrimer can be directly melt blended to obtain tough and thermostable blends with desirable microstructures and interfacial interaction. Bond exchange facilitates the grafting of PBT and epoxy vitrimer chains, thus enhancing the interfacial compatibility and thermal stability of blends. The obtained blend balances the strength and stretchability of PBT and epoxy vitrimer, resulting in enhanced toughness. This work offers a new way for designing and fabricating new polymeric materials by blending thermoplastics and thermosets. It also suggests a facile direction towards upcycling thermoplastics and thermosets. This article is protected by copyright. All rights reserved.

Thermoreversibly crosslinked silica-rubber composite prepared via melt processing

This paper addresses the industrially viable and environmentally sustainable preparation of thermoreversibly crosslinked composite rubbers. A maleimide-functionalized silica (Sil-M) is prepared and used as a reinforcement filler and crosslinking agent via Diels-Alders (DA) reaction onto furan-grafted ethylene-propylene rubber (EPRgF). The preparation of composite rubbers is carried out by reactive melt blending to guarantee for industrial scalability and avoiding use of organic solvent. Mechanical properties of EPRgF/Sil-M is compared to unfunctionalized EPRgF/Sil to demonstrate the role of DA crosslinking on mechanical properties. Furthermore, the combination between Sil-M and bismaleimide as a conventional DA crosslinker was investigated, to optimize crosslinking degree and materials performances. Overall, results reported in this paper demonstrate the possibility to develop a new class of recyclable composite rubbers for the substitution of conventional rubbers, that are currently causing major problems in the management of rubber products at their end-of life.

Rigid molecular chains trapped reactive elastomers for high performance PLLA composites with excellent tough-strength balance

The enhancement in the stiffness-toughness balance of PLLA composites poses great challenges. Herein, we proposed a two-step reactive processing strategy to design unique “sub-inclusion” microstructure for high performance polylactide (PLLA) composites. The rigid PLLA chains trapped reactive elastomer (RCRE) was first prepared by the reactive blending of a multiple-carboxyl PLLA (mcPLLA) with the random copolymer of ethylene-acrylic ester-glycidyl methacrylate (EGMA). The pre-grafted mcPLLA chains can be fixed and trapped in the rubber domains, inducing sub-inclusion morphology after the following mixing of RCRE with the virgin PLLA. Promisingly, excellent stiffness-toughness balance can be realized: on the one hand, the notched impact strength of the obtained PLLA alloys was as high as 58.7 kJ/m2, which was more than 8 times of the virgin EGMA toughened PLLA blend (7.0 kJ/m2) at the same EGMA content (15 wt%); on the other hand, the Young's modulus and tensile strength kept almost the same (1.4 GPa and 47 MPa). The synergistic improvement of the PLLA composites is attributed to the sub-inclusion structure in the dispersed rubber domains, as well as the strong interfacial adhesions. This work expands the scope promising to prepare high-performance polymer composites with excellent stiffness-toughness balance via construction of sub-inclusion morphology, and also provides depth of understanding on toughening mechanism for plastic/elastomer system.

Toward supertough and heat-resistant binary blend: polyoxymethylene/elastomer via in-situ graft copolymer formation during one-pot reactive melt blending

Toward supertough and heat-resistant binary blend: polyoxymethylene/elastomer via in-situ graft copolymer formation during one-pot reactive melt blending

Boosting Degradation of Biodegradable Polymers.

Biodegradation of polymers in composting conditions is an alternative end-of-life (EoL) scenario for contaminated materials collected through the municipal solid waste management system, mainly when mechanical or chemical methods cannot be used to recycle them. Compostability certification requirements are time-consuming and expensive. Therefore, approaches to accelerate the biodegradation of these polymers in simulated composting conditions can facilitate and speed up the evaluation and selection of potential compostable polymer alternatives and inform faster methods to biodegrade these polymers in real composting. This review highlights recent trends, challenges, and future strategies to accelerate biodegradation by modifying the polymer properties/structure and the compost environment. Both abiotic and biotic methods show potential for accelerating the biodegradation of biodegradable polymers. Abiotic methods, such as the incorporation of additives, reduction of molecular weight, reduction of size and reactive blending, are potentially the most straightforward, providing a level of technology that allows for easy adoption and adaptability. Novel methods, including the concept of self-immolative and triggering the scission of polymer chains in specific conditions, are increasingly sought. In terms of biotic methods, dispersion/encapsulation of enzymes during the processing step, biostimulation of the environment, and bioaugmentation with specific microbial strains during the biodegradation process are promising to accelerate biodegradation.

Theoretical and experimental investigation of selective gas permeability in polystyrene/polyolefin elastomer/nanoclay nanocomposite films

Nanoclay (NC) has gas barrier properties that, when used in food packaging, protects food against spoilage. Moreover, food packaging frequently makes use of rigid and foamed polystyrene (PS). In this work, reactive blending in a co-rotating twin-screw extruder was used to process PS, polyolefin elastomer (POE), and NC blends, leading to microphase-separated PS/POE/NC nanocomposite films. The structural and CO2 and N2 barrier properties of the resulting films were determined. The distribution of the NC platelets in the blends was theoretically predicted using the wetting coefficients. Nearly all NC platelets were found in the PS phase, in agreement with the theoretical predictions. Moreover, the NC platelets were found to be concentrated at the interfacial zones between the polymer phases when a compatibilizer was added to the blend. Scanning electron microscopy, wide-angle X-ray scattering, and transmission electron microscopy were used to examine the microstructure of the PS/POE/NC nanocomposites. Adding NCs as a gas barrier component to the PS/POE blend resulted in a decrease in CO2 and N2 permeability. For a better understanding of the gas diffusion in the pure PS and POE, as well as PS/POE blend, molecular dynamics simulations were performed to enable the calculation of gas diffusion coefficients in the different systems. The simulation results confirmed the experimental trends observed in this work.

Morphology, Mechanical Properties, and Biodegradability of Modified Thermoplastic Starch/PETG Blends with In Situ Generated Graft Copolymers

This paper reports on synthesis of modified thermoplastic starch (MTPS) and glycol-modified polyethylene terephthalate (PETG) blends in a twin-screw extruder. Scanning electron microscopy (SEM) images showed uniform, microdispersion of MTPS in PETG matrix, confirming compatibilization of the blend by graft copolymers generated in situ during the reactive extrusion process. Incorporating 30% by wt. MTPS in the blend gives a biobased carbon content of 22.8%, resulting in reduced carbon footprint by removal of 0.5 kg CO2 from the environment/kg resin relative to unmodified PETG. MTPS with 80% glycerol grafted onto starch was prepared by reactive extrusion in the twin-screw extruder. A total of 33% of added PETG was grafted on MTPS backbone as determined by soxhlet extraction with dichloromethane (DCM). The grafting was confirmed by presence of PETG peak in the TGA analysis of residue and appearance of carbonyl peak in FTIR spectra of the residue after Soxhlet extraction. The synthesized MTPS–PETG reactive blend had lower but acceptable mechanical properties. Even after a 15% reduction in the tensile stress and 40% reduction in the strain and impact strength obtained after adding 30% MTPS, this blend still had good mechanical properties and can be used in many applications requiring a balance of cost, mechanical properties, and biobased content. Aqueous biodegradability studies using ISO 14852 showed that the 30% starch component in the blend biodegraded rapidly within 80 days, whereas PETG remained as it was even after 150 days. Thus, this study categorically proves that addition of starch does not improve the biodegradability of nonbiodegradable polymers.

Blending as a process for controlling the properties of poly(ethylene 2,5-furandicarboxylate) (PEF): Fully biobased PEF/PBF blends

2,5-Furandicarboxylic Acid (FDCA) is the most important aromatic monomer from biomass. It is used in the production of sustainable bioplastics, such as poly(ethylene 2,5-furandicarboxylate) (PEF). Blending is a sustainable process for materials with tailored properties. A series of fully biobased poly(ethylene 2,5-furandicarboxylate)/poly(butylene 2,5-furandicarboxylate) (PEF/PBF) blends were prepared. The blends showed partial miscibility. PEF crystallized faster in the blends with PBF, compared to neat PEF. This is beneficial for PEF's industrialization. The miscibility of the blends increased with reactive blending. With increasing melting temperature and time, a single Tg appeared after a shorter time, however there was a significant drop in the polyesters' molecular weight. Low melt mixing temperatures are the optimum. In such a case, the crystallization rates of both PBF and PEF still remain satisfactory. Finally, PEF-PBF blends are based on FDCA polyesters alone, which is a benefit in the recycling of the materials.

A Cross-linked Polyethylene with Recyclability and Mechanical Robustness Enabled by Establishment of Multiple Hydrogen Bonds Network via Reactive Melt Blending

A Cross-linked Polyethylene with Recyclability and Mechanical Robustness Enabled by Establishment of Multiple Hydrogen Bonds Network via Reactive Melt Blending

Design of fully biodegradable super-toughened PLA/PBAT blends with asymmetric composition via reactive compatibilization and controlling morphology

• PLA/PBAT blends with co-continuous structure have been fabricated. • Diisocyanate and stereocomplex crystallites of PLA are simultaneously used, for the first time, to achieve co-continuous structure in PLA/flexible polymer blend with asymmetric composition. • The fully biodegradable PLA/PBAT blends exhibit supertoughness with the notched impact strength of 62.6 kJ/m 2 . Super-toughened poly(lactic acid) (PLA)/poly(butylene-adipate-co-terephthalate) (PBAT) blends with co-continuous structure were successfully prepared by taking the advantage of reactive blending and stereocomplex (SC) crystallites located at the interface and poly(l-lactic acid) (PLLA) matrix. In order to generate SC crystallites, poly(d-lactic acid) (PDLA), PBAT and an isosorbide-based diisocyanate (IBDI) were firstly melt blended to prepare masterbatch. Then, it was melt mixed with PLLA to in situ form SC crystallites. Based on this two-step processing strategy, the influence of rotating speed of second mixing step on the formation of co-continuous structure is also investigated. Relatively low rotating speed (30 r/min) would lead to a more perfect co-continuous structure with superior impact strength of 62.6 kJ/m 2 compared with the blends mixed at the intermediate rotating speed (60 r/min). When the rotating speed increases to 90 r/min, the co-continuous structure breaks into irregular particles and the impact strength decreases to 30.0 kJ/m 2 .

Barrier and Seal Properties of Reactive Blending of Poly(butylene succinate) Based Blends

Poly Butylene Succinate (PBS) is one of the biodegradable polymers with good physical properties but its barrier properties such as the oxygen barrier are poor. The aim of this study was to investigate the barrier and seal properties of PBS by blending with biodegradable poly hydroxybutyrate-co-hydroxyvalerate (PHBV). PBS and PHBV (80/20 and 70/30 %w/w) with and without reactive agents were prepared using an internal mixer. Film specimens of 100 micrometers in thickness were prepared using compression molding. The morphology, barrier properties and peel-seal strength were investigated. Morphological observations using scanning electron microscope (SEM) showed an improved dispersion of PHBV in the blends after adding the reactive agents. The oxygen barrier and water vapor barrier were determined using ASTM D3985 and ASTM E96, respectively. The results showed that the addition of PHBV into the blend films led to lower OTR and WVTR when compared to the neat PBS. The addition of reactive agents can further improve the OTR and WVTR of PBS/PHBV blends due to the compact and dense structure of the films. Peel–seal behavior of the films was examined by the different sealing temperatures, which determined the failure mechanism after peeling. The blend films with reactive agents after sealing temperature between 105 and 115°C were peeled from the substrate with adhesive and cohesive failures showing the easy peel mode.

Antimicrobial thermoplastic starch reactive blend with chlorhexidine gluconate and epoxy resin

An antimicrobial thermoplastic starch (TPS) was developed by melt-mixing TPS with chlorhexidine gluconate (CHG) and epoxy resin (Er). The tensile strength and hardness of the TPSCh blend increased with the addition of Er (TPSCh/Er), especially at 5 wt% Er (TPSCh/Er5) (19.5 MPa and 95 %, respectively). The water contact angle of TPSCh/Er was higher than those of TPS and TPSCh because of the improved interfacial tension. Fourier transform infrared and nuclear magnetic resonance analyses confirmed the reaction between the epoxy groups of Er, hydroxyl groups of starch, and amino groups of CHG. TPSCh/Er5 exhibited a significantly lower CHG release than TPSCh owing to the rearrangement of TPSCh chains via Er crosslinking. TPSCh/Er0.5 and TPSCh/Er1 showed inhibition zones against both tested bacteria (Staphylococcus aureus and Bacillus cereus), whereas TPSCh/Er2.5, TPSCh/Er5, and TPSCh/Er10 showed inhibition zones only against S. aureus. Moreover, TPSCh and TPSCh/Er0.5–2.5 exhibited inhibition zones with Saccharomyces cerevisiae.

Phase-field simulations of morphology development in reactive polymer blending

Reactive blending is an efficient method for synthesizing polymer blends. Industrially, this process is carried out in extruders, where the reacting polymers and the generated copolymer are subjected to high shear stresses. The dynamics of the process, and the resulting morphology is dictated by a coupling of the hydrodynamic forces in the extruder, the thermodynamic interactions between species, and the reaction kinetics on a complex interfacial manifold. We use phase-field simulations to quantify the evolution of the reactive blending process under an external shear flow. Specifically, we consider a model system of two homopolymers of equal length, which react via an end-coupling reaction to form a diblock copolymer of double the length. We compare the morphology development in two different initial geometries of the homopolymers—a cylindrical thread and a drop of one homopolymer in a matrix of the second. We investigate the effect of flow strength, measured by the shear rate, and reaction kinetics, quantified by a Damkohler number, on the progress of the reaction and morphology development. Cylindrical threads are susceptible to breakup via the Rayleigh capillary instability. We demonstrate that this instability can be suppressed by imposing shear along the direction of the thread and increasing the extent of the reaction. The reaction rate in this geometry is unaffected by shear imposed along the cylinder axis. Drops deform significantly under an imposed flow, eventually stretching to long cylindrical threads for sufficient shear rates. In the case of drops, shear stresses enhance the reaction rate by deforming the drop, enabling more homopolymers to come in contact at the expanded interface. We show that shear stresses significantly impact the morphology development and reaction dynamics in reactive polymer blending.

Blending PLA with Polyesters Based on 2,5-Furan Dicarboxylic Acid: Evaluation of Physicochemical and Nanomechanical Properties

Poly(lactic acid) (PLA) is a readily available, compostable biobased polyester with high strength and toughness, and it is excellent for 3D printing applications. Polymer blending is an economic and easy way to improve its properties, such as its slow degradation and crystallization rates and its small elongation, and thus, make it more versatile. In this work, the effects of different 2,5-furan dicarboxylic acid (FDCA)-based polyesters on the physicochemical and mechanical properties of PLA were studied. Poly(butylene furan 2,5-dicarboxylate) (PBF) and its copolymers with poly(butylene adipate) (PBAd) were synthesized in various comonomer ratios and were blended with 70 wt% PLA using melt compounding. The thermal, morphological and mechanical properties of the blends are investigated. All blends were immiscible, and the presence of the dispersed phases improved the crystallization ability of PLA. Mechanical testing revealed the plasticization of PLA after blending, and a small but measurable mass loss after burying in soil for 7 months. Reactive blending was evaluated as a compatibilizer-free method to improve miscibility, and it was found that when the thermal stability of the blend components allowed it, some transesterification reactions occurred between the PLA matrix and the FDCA-based dispersed phase after 20 min at 250 °C.

Vitrimer-like transparent blend films based on reactive blending of PC and PMMA with catalysis of Mg(TFSI)2

Dynamic covalent bonding can be used to construct covalent adaptable networks (CANs), which show superior properties compared to thermosetting networks. Compared to chemical synthesis or functional modification of polymers, reactive processing of polymers is a facial method to fabricate CANs. By reactive blending of commodity polymers PC and PMMA with catalysis of readily available organic salt Mg(TFSI)2, we fabricated transparent vitrimer-like blend films. After reactive blending in twin-screw extruder, an elution experiment with mutual solvent (chloroform) of PC and PMMA was done on the blends and it turns out to be presence of some insoluble residuals, revealing a crosslinked network formation. Compression molding of the insoluble network leads to transparent films, indicating a covalent adaptable network formation. The CANs are swollen in THF or chloroform at room temperature, but soluble at high temperatures, revealing a dissociative bonding mechanism. Rheological analysis shows that shift factors follow an Arrhenius relationship against 1/T, suggesting a vitrimer-like behavior.

Highly toughened poly(ʟ-lactide) by poly(ᴅ-lactide)-containing crosslinked polyurethane shows excellent malleability, flexibility and shape memory property

The brittle nature of poly(ʟ-lactide) (PLLA) limits its extensive application. In the present work, PLLA was toughened by crosslinked polyurethane (CPU), which was formed by reactive blending of poly(ε-caprolactone) (PCL), poly(d-lactide) (PDLA), hexamethylene diisocyanate (HDI) and glycerol. PCL segments in the network acted as soft segments while PDLA segments served as hard segments to form stereocomplex (SC) crystallites as physical crosslinking points. The disappearing peak at 2270 cm−1 and the emerging absorption peak appeared at 1530 cm−1 in the FTIR spectrum proved the formation of the network in the modified PLLA. The melt-quenched specimens containing the network showed significant increase in elongation at break, and the CPU80/18/2 blend showed a maximum value of 428.6%. Tensile-fractured surfaces of all the blends exhibited fibril-like morphologies because of the matrix shear yielding caused by large deformation. And the crystallization rate could be accelerated because of the PDLA chains in the sample comparing to the CPU80/20 without PDLA. Interestingly, when SC crystallites could be formed after annealing of the melt-quenched specimens at 110 °C for 1h, CPU80/18/2 still owned a maximum value of 152.8% of elongation at break. It was found that the CPU phase was presented as continuous phase in the material. Due to the compatibility, the added PDLA chains were distributed in the interface of CPU and PLLA phase, which provided additional interfacial adhesion, improved the stress transmission and endowed the material with enhanced toughness. The CPU80/18/2 sample also showed the malleability, flexibility and shape memory capacity, implying great application potential as biodegradable green composites.

Supertough polylactide-based materials with fast shrinking property by stereocomplex crystallites through in situ reactive blending

Polylactide (PLA), one of the most innovative biopolymers with excellent performance, can be produced from plant-derived resources. However, the brittleness of PLA limits its further applications. In this work, supertough poly(L-lactide) (PLLA)-based materials with fast shrinking property have been prepared by blending PLLA, poly(D-lactide) (PDLA), and ethylene-acrylic ester-glycidyl methacrylate random terpolymer (EGMA). It was confirmed that PLLA and PDLA can react with EGMA to form a strong interfacial interaction. With the addition of PDLA component, the EGMA phase structure changed from a sea-island structure to a cocontinuous-like phase structure, and the stereocomplex (SC) crystallites appeared at the interface between PLLA matrix and EGMA phase. Compared to pristine PLLA, the ternary blend containing 70 wt% PLLA, 10 wt% PDLA, and 20 wt% EGMA exhibited high notched Izod impact strength (83.9 KJ/m2) and high elongation at break (242 %). XRD results indicate that only SC crystallites can be found in these PLLA/PDLA/EGMA blends. Interestingly, these supertough PLLA-based material films can shrink in hot water within 2 s without changing the mechanical property even after three stretching-shrinking cycles. The presence of SC crystallites and strong interfacial interaction between EGMA and PLLA matrix leads to significantly enhanced toughness, which opens a new path for high-performance PLLA-based materials in medical and packaging areas.