Polyurethane Sheets Research Articles

An Innovative Approach to Enhance the Durability and Sustainability of Shoe Insoles

This study presents an innovative approach to designing a shoe insole with enhanced durability, sustainability, and antibacterial properties. Needle-punched non-woven recycled polyester fabrics with three different GSMs (100, 200, and 300) were developed. The composite shoe insole was developed using non-woven fabric laminated with a polyurethane sheet to enhance durability. The fabrics were treated with an antibacterial finish with three different concentrations (5%, 10%, and 15%) and subjected to 5 and 10 washing cycles. The developed composites were evaluated against their relative hand value, abrasion resistance, tensile strength, antibacterial activity, and overall moisture management capability. Overall results reveal that the developed composite shoe insole is durable, sustainable, and presents no bacterial growth, demonstrating the insole’s hygienic effectiveness.

Impact of cellulose enrichment on castor oil polyurethane sheets: A path to greener materials

AbstractDue to the growing concern over the depletion of the global crude oil stock and environmental issues, the replacement of petroleum‐based polymers with environmentally benign alternatives derived from renewable resource has attracted great attention. In the current study, four different polyurethane (PU) sheets were synthesized from unmodified castor oil (CO) and hexamethylene diisocyanate (HDI), incorporating cellulose nanofibers (CNF) as a filler. The mixture consisting molar ratio of CO, HDI, and CNF in a ratio of 1:5:0.8 yielded the best results. This formulation achieved a tensile strength of 22.55 MPa and an elongation at break of 55.9%. Additionally, the resulting PU sheets exhibited excellent thermal properties, with a glass transition temperature (Tg) and melting temperature (Tm) that were notably enhanced, further highlighting the effectiveness of this specific mixture in producing high‐performance, bio‐based PUs. Fourier‐transform infrared spectroscopy (FTIR), thermal, and mechanical characterizations indicated that both reinforced and unreinforced PU exhibited properties within acceptable ranges. Given the bio‐based origins of CO and cellulose, the synthesized polymers are biodegradable and suitable for biomaterial applications. The study confirms that the bio‐based origins of CO and cellulose render synthesized polymers biodegradable, suitable for various biomaterial applications.

A promising strategy for enhancing fire resistance of steel structure: a composite thermoplastic polyurethane sheet adhered to steel plate

It is an effective passive fire protection method for the steel structure by painting fireproof coatings. Here, a feasible strategy for enhancing the fire resistance of steel structures is proposed. Specifically, a kind of adhesive composite sheet based on thermoplastic polyurethane (TPU), ammonium polyphosphate (APP), polyhedral oligomeric octaphenylsilsesquioxane (OPS), titanium dioxide (TiO2) and sodium silicate was constructed and named as Sheet-Ti/Na. The as-prepared Sheet-Ti/Na exhibited excellent flame retardancy and smoke suppression performance. In addition, the Sheet-Ti/Na can firmly adhere to the steel plate through hot pressing and adhesive bonding methods, acting as a non-traditional fireproof “coating”. This feasible coating method can effectively enhance the fireproof and thermal insulation of the steel plates under the action of the hydrocarbon fire at about 1100 ℃. After testing, the char layer of Sheet-Ti/Na can still firmly adhere to the steel plate without any detachment or cracking. Finally, a ceramic-like reaction among TiO2, APP, OPS and sodium silicate to generate pyrophosphates (TiP2O7 and SiP2O7) was clarified. The thermal insulation, flame retardancy and smoke suppression mechanisms of the Sheet-Ti/Na system also were stated. This work offers a promising strategy for rapidly and efficiently preparing fireproof and thermal insulation “coatings” for steel structures.

Enhancing heat dissipation in polyurethane sheets through the incorporation of freeze‐dried aluminum nitride nanofiber

AbstractInspired by a three‐dimensional (3D) structure, we demonstrate 3D aluminum nitride (AlN) nanofibers fabricated by a freeze‐drying technique using polyvinyl alcohol (PVA)/boehmite precursor nanofibers. After applying hot pressing, a series of PVA/boehmite precursor nanofibers were prepared with varying PVA‐to‐boehmite ratios (30/70 wt%, 50/50 wt%, and 70/30 wt%). Our findings reveal that the thermal conductivity of the AlN composite nanofibers is significantly affected by the relative proportions of PVA and boehmite, where the ratio of PVA should be more significant than that of boehmite. We produced AlN nanofibers at a lower temperature (1500°C) than the theoretical formation temperature of AlN (1664°C). The minimum specific surface area and pore volumes were 8.39 m2/g and 0.0166 cm3/g, respectively, at 1500°C. X‐ray photoelectron spectroscopy spectra measured 38.27% aluminum and 23.55% nitrogen in AlN nanofibers. The aligned AlN nanofibers mat was impregnated with polyurethane (PU), which showed good thermal conductivity in the planar (4.1–13.6 W/(m·K)) and thickness (1.5–4.9 W/(m·K)) directions at 18–56 vol% AlN nanofibers content. The heat‐dissipating sheet also showed superior electrical insulating (1.2 × 1012 Ω/cm2) properties. In this study, the author sought to develop a heat‐spreading material made of thermally conductive, but electrically insulating PU/AlN nanofibers that could efficiently dissipate heat from electric devices.

Proof of concept testing of a positive reference material for in vivo and in vitro sensitization testing of medical devices.

In vivo skin sensitization tests are required to evaluate the biological safety of medical devices in contact with living organisms to provide safe medical care to patients. Negative and positive reference materials have been developed for biological tests of cytotoxicity, implantation, hemolysis, and in vitro skin irritation. However, skin sensitization tests are lacking. In this study, polyurethane sheets containing 1 wt/wt % 2,4-dinitrochlorobenzene (DNCB-PU) were developed and evaluated as a positive reference material for skin sensitization tests. DNCB-PU sheet extracts prepared with sesame oil elicited positive sensitization responses for in vivo sensitization potential in the guinea pig maximization test and the local lymph node assay. Furthermore, DNCB-PU sheet extracts prepared with water and acetonitrile, 10% fetal bovine serum-containing medium, or sesame oil elicited positive sensitization responses as alternatives to animal testing based on the amino acid derivative reactivity assay, human cell line activation test, and epidermal sensitization assay, respectively. These data suggest that the DNCB-PU sheet is an effective extractable positive reference material for in vivo and in vitro skin sensitization testing in medical devices. The formulation of this reference material will lead to the development of safer medical devices that contribute to patient safety.

Particle elastic modulus analysis of waterborne polyurethane nanoparticles by ultrasound scattering method

Abstract When water is dropped gradually to an acetone solution of concentrated polyurethane containing ionic functional groups, a phase inversion occurs and nanoparticles of waterborne polyurethane (WPU) are formed. Evaporation of water from such aqueous particle suspensions yields polyurethane sheets, but the properties of these sheets are different from those obtained by evaporation of solvent from WPU acetone solutions. In this study, ultrasonic spectroscopy analysis combined with an ultrasonic scattering theory was performed on the microparticle suspensions to evaluate the elastic modulus of the individual particles. The nanoparticles obtained by phase inversion are stabilized by ionic substituents, and the bulk modulus of the particles at 30 wt% was shown to be different from that of bulk sample obtained by drying acetone, in spite of the fact that they are the same polymer material. Even after 95% concentration beyond the maximum packing concentration, the film properties were observed to be particle size dependent, suggesting that the nanostructure plays an important role in film properties.

Evaluation of the Effect of Nanocoating on Mechanical and Biofilm Formation in Thermoplastic Polyurethane Aligner Sheets.

The objective of this research is to determine whether the thermoplastic polyurethane (TPU) coated with carboxymethylcellulose chitosan has better mechanical and antibacterial action (anti-Streptococcus mutans) when utilized in intraoral simulations with synthetic saliva. The TPU sheets (n = 45) were divided into three groups. Control (n = 15) consists of as-received TPU sheets. Test 1 consists of TPU sheets coated with carboxymethyl cellulose (CMC) chitosan (CHI) (n = 15). Test 2 consists of thermoformed nano-coated TPU (n = 15). For the polyurethane sheets, CHI-CMC sheets, and thermoformed CHI-CMC sheets, scanning electron microscopy (SEM) and three-point flexural tests were conducted and assessed. The materials testing software was used to calculate the elastic modulus and tensile strength. To study the bacterial accumulation, the cut circles of the TPU aligner were placed in centrifuge tubes with 2.5 mL of bacterial suspension at a concentration of 104 or 105 CFU/mL. SEM was done to assess the presence of cell growth in all three groups. According to SEM analyses of bacterial buildup, the coated TPU had minimal biofilms compared to the bare TPUs numerous biofilms. The effect of aging on coating thickness reveals that the thickness of thermoformed coated TPU films dramatically decreased over time, while the thickness of coated TPU films was maintained. When TPU is coated with CMC/CHI, the elastic modulus and tensile strength were observed to improve. The development of a super-hydrophilic coating by the CHI CMC coating on TPU sheets improved the coating's biocompatibility while also changing the shape of the multilayer film to prevent bacterial adhesion. The effect on the improvement in the mechanical properties diminished after the material underwent a thermoforming process. It is therefore suggested that the nanofilm be used in therapeutic applications following the thermoforming process.

Diamond-like carbon coating to inner surface of polyurethane tube reduces Staphylococcus aureus bacterial adhesion and biofilm formation

Staphylococcus aureus is one of the main causative bacteria for polyurethane catheter and artificial graft infection. Recently, we developed a unique technique for coating diamond-like carbon (DLC) inside the luminal resin structure of polyurethane tubes. This study aimed to elucidate the infection-preventing effects of diamond-like carbon (DLC) coating on a polyurethane surface against S. aureus. We applied DLC to polyurethane tubes and rolled polyurethane sheets with our newly developed DLC coating technique for resin tubes. The DLC-coated and uncoated polyurethane surfaces were tested in smoothness, hydrophilicity, zeta-potential, and anti-bacterial properties against S. aureus (biofilm formation and bacterial attachment) by contact with bacterial fluids under static and flow conditions. The DLC-coated polyurethane surface was significantly smoother, more hydrophilic, and had a more negative zeta-potential than did the uncoated polyurethane surface. Upon exposure to bacterial fluid under both static and flow conditions, DLC-coated polyurethane exhibited significantly less biofilm formation than uncoated polyurethane, based on absorbance measurements. In addition, the adherence of S. aureus was significantly lower for DLC-coated polyurethane than for uncoated polyurethane under both conditions, based on scanning electron microscopy. These results show that applying DLC coating to the luminal resin of polyurethane tubes may impart antimicrobial effects against S. aureus to implantable medical polyurethane devices, such as vascular grafts and central venous catheters.

Effect of thermomechanical aging of orthodontic aligners on force and torque generation: An in vitro study

The aim of the study is to investigate the effects of artificial aging by thermocycling and mechanical loading on force/torque delivery by thermoplastic orthodontic aligners. Ten thermoformed aligners, made of Zendura™ thermoplastic polyurethane sheets, were aged over two weeks in deionized water by thermocycling alone (n = 5) and by both thermocycling and mechanical loading (n = 5). The force/torque generated on upper second premolar (Tooth 25) of a plastic model was measured before aging (as control), and after 2, 4, 6, 10, and 14 days of aging, using a biomechanical set-up. Before aging, the extrusion-intrusion forces were in the range of 2.4–3.0 N, the oro-vestibular forces were 1.8–2.0 N, and the torques on mesio-distal rotation were 13.6–40.0 Nmm. Pure thermocycling had no significant effect on the force decay of the aligners. However, there was a significant decrease in force/torque after 2 days of aging for both thermocycling and mechanical loading aging group, which is no longer significant over 14 days of aging. In conclusion, artificial aging of aligners in deionized water with both thermocycling and mechanical loading results in a significant decrease in force/torque generation. However, mechanical loading of aligners has a greater impact than pure thermocycling.

Primary Stability Assessment of Conical Implants in Under-Prepared Sites: An In Vitro Study in Low-Density Polyurethane Foams

Bone characteristics, the implant macrogeometry, and the drilling technique are considered the main important factors to obtain a good implant primary stability (PS). Indeed, although it is known that implant placement in poor bone sites increases the possibility of implant failure, several surgical procedures have been proposed to improve PS, such as site under-preparation. Hence, this in vitro study aimed to evaluate the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) of conical implants (3.3 and 4 × 13 mm) placed in under-prepared sites on 10 and 20 pounds per cubic foot (PCF) density polyurethane sheets (simulating a D3 and D2 bone, respectively) with and without a cortical sheet of 30 PCF in density (corresponding to a D1 bone). After using ANOVA or Kolmogorov–Smirnov test to elaborate data, the resulting IT and RT values were directly proportional to the polyurethane block densities (e.g., the lowest and highest IT values were 8.36 ± 0.52 Ncm in the 10 PCF density sheet and 46.21 ± 0.79 Ncm in the 20 PCF density sheet + cortical for 4 × 13 mm implants) and increased with the increasing amount of site under-preparation (the highest results for both implants were found with a 2.2 mm under-preparation, showing a significantly higher IT with a p < 0.05 compared with others, especially in the highest-density sheets). Both implants inserted in the 20 PCF density block + cortical with all under-preparation protocols exhibited significantly higher RFA values (p < 0.05–0.0001) compared with the corresponding ones in the 10 PCF block. Moreover, 3.3 × 13 mm implants showed the same results comparing the 20 PCF block and the 10 PCF block + cortical. In conclusion, in this in vitro study using low-density polyurethane blocks, the under-preparation of the implant insertion sites was shown to be effective in increasing implants’ PS.

Bioinspired Polycation Functionalization of the Polyurethane Surface for Enhanced Lubrication, Antibacterial Property, and Anticoagulation

Endowing the implanted biomaterial with a wide range of functions, such as lubrication and antibacterial and anticoagulation properties, is essential for their safe clinical use. In the present study, based on the superlubrication mechanism of articular cartilage, a branched polyelectrolyte polymer (PEI-PMPC) was successfully synthesized based on tert-butyl hydroperoxide-initiated grafting polymerization and then applied to the biocompatible polyurethane (PU) surface. Specifically, the PU sheet was pretreated by polydopamine (PDA), and the PEI-PMPC polymer was grafted onto the PDA-modified PU surface by Schiff base reaction to generate a solid PDA/PEI-PMPC coating. The unmodified and modified surfaces were characterized by Fourier transform infrared spectroscopy, water contact angle, X-ray photoelectron spectroscopy, and surface zeta potential. To compare the lubrication, antibacterial behavior, and hemocompatibility, the relevant properties of the modified surfaces were evaluated by the tribological test, plate count method, surface morphology, hemolysis rate, activated partial thromboplastin time, and thrombin time. The experimental results demonstrated that the adhesion of bovine serum albumin, Escherichia coli, Staphylococcus aureus, platelets, and red blood cells was significantly decreased on the PEI-PMPC-modified PU surface compared with that of the unmodified PU surface. The multi-functional properties of the coating were attributed to the hydration layer formed by zwitterionic phosphorylcholine groups, and additionally, the cationic PEI served to kill the bacteria adhering to the surface. In summary, the bioinspired coating proposed in this study could potentially be used as a promising surface functionalization strategy for biomedical implants.

Heat Transfer Rate Analysis of Different Roof Insulation Materials

The building sector is crucial in Middle East countries because it is one of the primary energy consumers. Currently, reinforced cement concrete (RCC) is preferred for roof construction due to its durability and possesses higher strength. Heat is conducted rapidly through rooftops composed of RCC because it has more thermal conductivity compared to other roofing materials. In the Middle East, RCC roofs are usually lined with marble and polyurethane to increase thermal insulation and reduce heat transfer from the roofs. In this research, the thermal conductivities and temperature reduction capabilities of distinct material combinations for roof insulation have been investigated. The rates of heat conduction were estimated, and a suitable roof combination was found based on the maximum heat resistance and temperature reduction ability. The hot plate guarded method determines the thermal conductivity of marble and polyurethane sheets. Fourier law of heat conduction was employed to calculate the rate of heat flow through roof samples. According to the experimental findings, compared to concrete without insulation, the rate of heat conduction was reduced by 11.8% with combination B (RCC lined with marble) and by 84.3% with combination C (RCC lined with marble and polyurethane).

Insertion Torque, Removal Torque, and Resonance Frequency Analysis Values of Ultrashort, Short, and Standard Dental Implants: An In Vitro Study on Polyurethane Foam Sheets.

Short implants were introduced to reduce morbidity, treatment duration, and complex bone regeneration interventions in atrophic jaws and to improve patient-reported outcomes. This study aimed to determine the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) values of ultrashort (3 mm length), short (7 mm length), and standard implants (10 mm length) inserted in 1-, 2-, 3-, and 4-mm thickness polyurethane sheets with densities of 10, 20, and 30 pounds per cubic foot (PCF). Standard-length implants were the gold standard (control). Overall, short-length implant IT values were higher or similar to the control in most experimental conditions. Those inserted into a 3 mm/30 PCF lamina showed the highest IT values, whereas 5 mm diameter ultrashort-length implants inserted into 2 and 3 mm/20 PCF laminas were higher than other implants. RT values followed the same trend and RFA values were more appreciable in short- and standard-length implants in all the scenarios. However, ultrashort-length implants reached a primary stability comparable to that of standard implants in lower thicknesses. In conclusion, although further studies are needed to corroborate this in vitro model with preclinical and clinical studies, our data shed light on short- and ultrashort-length implants geometries to a potential application in critical atrophy of the posterior jaws.

Application of High-Photoelasticity Polyurethane to Tactile Sensor for Robot Hands.

We developed a tactile sensor for robot hands that can measure normal force (FZ) and tangential forces (FX and FY) using photoelasticity. This tactile sensor has three photodiodes and three light-emitting diode (LED) white light sources. The sensor is composed of multiple elastic materials, including a highly photoelastic polyurethane sheet, and the sensor can detect both normal and tangential forces through the deformation, ben sding, twisting, and extension of the elastic materials. The force detection utilizes the light scattering resulting from birefringence.

Differences in the expression of myelopathy in a rat model of chronic spinal cord compression

Context/Objective The degree of spinal cord compression does not always parallel neurological symptoms. We considered that some compensatory neuroprotective mechanism underlies the expression of this neurological phenotype. Oxygen-regulated-protein 150 (ORP150) is neuroprotective and expressed in neurons in response to neuronal ischemia. We sought to elucidate whether ORP150 expression is associated with the severity and variation of neurological recovery in our rat model of chronic spinal cord compression. Methods We made a rat model of chronic spinal cord compression inserting an expandable water-absorbing polyurethane sheet. A neurological behavioral assessment of the severity of paralysis was performed for 10 weeks postoperatively. The rat model was defined as two groups: a myelopathy group with decreased locomotor function and an asymptomatic group. At 10 weeks postoperatively, the spinal cord of the cervical segment was resected for histology and qPCR. Results Slowly progressive paralysis appeared at 5–10 weeks postoperatively in 53% of the rats with spinal cord compression. The asymptomatic group had no histological changes indicative of myelopathy. Histology and qPCR showed increased expression of ORP150 in the asymptomatic group, but the ratio of ORP150-positive neuron in the two groups was not significantly different. Conclusion The expression of ORP150 in neurons associated with spinal cord compression suggested that the spinal cord was under ischemic stress due to compression, but relation to the development of myelopathy was unclear. The results suggested that some other compensatory mechanisms may exist in response to spinal cord compression in asymptomatic rats.

Industrial Preparation of Self-Lubricating Polyurethane via Direct Fluorination with Gaseous Fluorine.

Fluorination modification is an effective way to improve the friction property of a polymer; however, current preparation of fluorine-containing polymers is limited by the high cost and complex synthesis. Here, an industrial fluorination strategy with gaseous fluorine (F2) to achieve fluorine enrichment on the surface of a polyurethane (PU) sheet was demonstrated. Benefiting from the high reactivity and strong diffusion of F2 gas, the as-prepared PU sample was characterized by the rich fluorinated surface with the slightly fluorinated bulk. As a result, the fluorinated PU combined the excellent mechanical properties of pristine PU with the unique function of the fluorine-containing polymer, where the fluorinated surface may function as a robust lubricating layer, contributing to remarkable promotion of friction property while maintaining the mechanical strength unchanged. The friction coefficient decreased to 0.5 at the dry condition and 0.1 at the wet condition from the initial value of 1 and 0.45 for the pristine PU sample. The surface manipulation via direct fluorination offers great opportunities to tailor the friction property while keeping the mechanical strength unchanged.

Hydroelastic responses of a Truss Pontoon Mobile Offshore Base – An experimental investigation

The present study focuses on the details of 1:150 scaled model tests conducted on a Semisubmersible type Very Large Floating Structures (VLFS), namely Truss Pontoon Mobile Offshore Base (TP-MOB) under regular waves. The laboratory tests were performed in a deep water wave basin at the Indian Institute of Technology Madras (IIT Madras). The model, governed by Froude and Cauchy scaling laws, was constructed of thermoplastic polyurethane (TPU) sheet with internal steel stiffener plates. The top deck was constructed using thicker TPU to bring in the elasticity effect. The responses of the model were measured for regular waves with different wave frequencies at a constant wave height of 0.04 m and various heading angles. Three different accelerometers recorded the responses at three different locations for different heading angles. From the recorded time series Response Amplitude Operators (RAOs) of vertical displacements, roll, and pitch are obtained. The characteristics frequency response curve obtained from the experiments are consistent with that reported in the literature by Suzuki et al. (1996). The results indicate the presence of resonant elastic modes in the wave excitation ranges. The uncertainty analysis carried out indicated that the uncertainty in the frequency responses is generally small for kd values greater than 0.2.

Textile-based pressure sensor arrays: A novel scalable manufacturing technique

Soft pressure sensors have sparked a lot of interest over the last decade because of their applications in human motion recognition, object detection, and human–computer interaction. However, their mass production and availability to end users are limited due to the complex and time-consuming steps. The scalability of working range for various applications is also a critical challenge. Therefore, a laborless, rapid, and scalable manufacturing technique for capacitive-based soft pressure sensors with high sensitivity and high working range is proposed in this work. The novel manufacturing method enables manipulation of sensor properties by varying production parameters based on specific application needs. The proposed sensor's electrode is made of conductive knit fabric, and the dielectric layers are made of thermoplastic polyurethane (TPU) sheets. As a result of the novel approach, it is possible to generate scalable air gaps between electrodes and dielectric layers to capture low pressures of less than 1 kPa. The usage of multi-layer TPU sheets also increases the working range of sensors up to 1000 kPa. Here, the proposed technology is successfully applied to create several sensor mats for different purposes such as improved gesture and shape recognition, and interactive gaming mats for children. • Simple and fast manufacturing of a novel textile pressure sensor. • Scalable with desired pattern of the sensor mat. • Adjustable sensitivity and wide working range from 1 kPa to 1000 kPa. • Pressure mapping for e-textiles, interactive software and human gesture recognition.

Thermal conductivity of polyurethane sheets containing beryllium oxide nanofibers.

Polyvinyl alcohol/beryllium sulfate/polyethyleneimine (PVA/BeSO4/PEI) precursor nanofibers (NFs) was first fabricated to obtain PVA/BeSO4/PEI electrospun NFs by electrospinning technology, finally manufactured beryllium oxide (BeO) NFs followed by various heat treatment methods. The minimum calcination temperature for pure BeO NFs was 1000 °C, and the minimum specific surface area (5.1 m2 g-1) and pore volumes (0.0128 cm3 g-1) were at 1300 °C. 46.18% Be and 53.82% O was measured in BeO NFs by X-ray photoelectron spectroscopy. BeO NFs were then impregnated with polyurethane (PU) aqueous solution to make PU/BeO NFs heat-dissipating sheet. This heat-dissipating sheet showed superior thermal conductivity (14.4 W m-1 K-1) at 41.4 vol% BeO NFs content. The electrical insulating properties of the heat-dissipating sheet were likewise excellent (1.6 × 1012 Ω □-1). In this study, the author attempted to create a thermally conductive but electrically insulating PU/BeO NFs heat-dissipating sheet that could effectively eliminate generated heat from electric equipment.

Enhancing the performance of conventional coffee beans drying with low-temperature geothermal energy by applying HPHE: An experimental study

Abstract The unpredictable weather in Indonesia results in a less effective conventional coffee beans drying process, which usually uses solar energy as a heat source. This experiment aimed to examine the performance of the coffee beans drying using low-temperature geothermal energy (LTGE) with solar energy as the energy source. Heat pipe heat exchanger, which consists of 42 straight heat pipes with staggered configuration, was used to extract the LTGE. The heat pipes have 700 mm length, 10 mm outside diameter with a filling ratio of 50%, and added by 181 pieces of aluminum with a dimension size of 76 mm × 345 mm × 0.105 mm as fins. LTGE was simulated by using water that is heated by three heaters and flowed by a pump. Meanwhile, to simulate the drying process with conventional methods, a system of solar air collectors made of polyurethane sheets with a thickness of 20 mm and dimensions of length × width × height = 160 cm × 76 cm × 10 cm, respectively, was used in this study. Zinc galvalume sheet with 0.3 mm thickness was installed and coated by the black doff color throughout the inner of the container wall. The result showed that the drying process with LTGE and solar energy is faster than with solar energy or geothermal energy only. The drying coffee beans using the hybrid system can speed up the drying coffee beans time by about 23% faster than the solar energy only.