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1.
Molecules ; 28(5)2023 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-36903250

RESUMEN

The various chemicals in industrial wastewater can be beneficial for improving its circularity. If extraction methods are used to capture valuable components from the wastewater and then recirculate them throughout the process, the potential of the wastewater can be fully exploited. In this study, wastewater produced after the polypropylene deodorization process was evaluated. These waters remove the remains of the additives used to create the resin. With this recovery, contamination of the water bodies is avoided, and the polymer production process becomes more circular. The phenolic component was recovered by solid-phase extraction and HPLC, with a recovery rate of over 95%. FTIR and DSC were used to evaluate the purity of the extracted compound. After the phenolic compound was applied to the resin and its thermal stability was analyzed via TGA, the compound's efficacy was finally determined. The results showed that the recovered additive improves the thermal qualities of the material.

2.
Curr Opin Urol ; 26(1): 70-5, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26555688

RESUMEN

PURPOSE OF REVIEW: Ureteral access sheath (UAS) became increasingly popular worldwide. However, the safety of its routine use remains controversial. The aim of the current revision is to provide a systematic review on the benefits and disadvantages of the UAS. RECENT FINDINGS: A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Two reviewers independently searched the literature, finally identifying 20 articles valuable for this review. The use of UAS demonstrated several advantages to facilitate retrograde intrarenal access, lower intrarenal pressure, protect the ureter, protect the scope, and expedite stone extraction. Despite this, there is also some evidence that UAS use may be associated with acute ureteral injury and long-term complications, apparently related to maneuvers for UAS insertion and mucosal or deeper layers of injury and ischemia. Furthermore, there are still pending questions on the possible increase in stone-free rates, and decrease in operative time and costs. SUMMARY: Although the use of UAS is associated with some risk and limiting factors, it appears from this systematic review that its use is common and safe for the retrograde intrarenal access. Therefore, UAS is highly recommended for the treatment of upper tract disease by means of retrograde intrarenal surgery.


Asunto(s)
Uréter/cirugía , Ureteroscopía/instrumentación , Urolitiasis/cirugía , Análisis Costo-Beneficio , Diseño de Equipo , Costos de la Atención en Salud , Humanos , Complicaciones Posoperatorias/etiología , Factores de Riesgo , Resultado del Tratamiento , Uréter/lesiones , Uréter/fisiopatología , Ureteroscopía/efectos adversos , Ureteroscopía/economía , Urolitiasis/diagnóstico , Urolitiasis/economía , Urolitiasis/fisiopatología
3.
J Urol ; 193(4): 1144-50, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25444981

RESUMEN

PURPOSE: Several risk factors have been claimed to predict the progression of clinically high grade T1 bladder tumors. However, these factors are not specific enough to define which patients should be treated immediately with radical cystectomy. Therefore, it is critical to identify molecular markers that can help provide individualized, risk stratified decision making. Our main goal was to evaluate the role of total p63, p53 and ΔNp63 expression in cases of clinically high grade T1 bladder cancer progression. MATERIALS AND METHODS: Total p63, p53 and ΔNp63 expression was analyzed by immunohistochemistry in 134 clinically high grade T1 tumors. We assessed clinical progression to muscle invasive disease or radical cystectomy as a patient outcome end point. Survival analysis was done for recurrence-free, progression-free, disease specific and overall survival. RESULTS: A total of 132 patients (98.5%) underwent repeat transurethral resection. Cases of early progression (less than 3 months) were excluded from study to avoid under staging. Of the tumors 90 (67.2%) showed ΔNp63 expression loss. During a median followup of 62.1 months 19 patients (14.2%) progressed to muscle invasive disease. The progression rate was 21.1% in patients with tumors characterized by ΔNp63 loss but no progression was observed in those with tumors with ΔNp63 expression (p <0.001). There was no difference in the number of patients who underwent repeat transurethral resection, had associated carcinoma in situ, showed lymphovascular invasion or received followup intravesical bacillus Calmette-Guérin courses. CONCLUSIONS: ΔNp63 expression is a favorable prognostic factor in clinically high grade T1 bladder cancer. This marker identifies patients at low risk for progression who could benefit from conservative therapy with transurethral bladder tumor resection and bacillus Calmette-Guérin, avoiding over treatment with immediate radical cystectomy.


Asunto(s)
Biomarcadores de Tumor/biosíntesis , Factores de Transcripción/biosíntesis , Proteínas Supresoras de Tumor/biosíntesis , Neoplasias de la Vejiga Urinaria/metabolismo , Neoplasias de la Vejiga Urinaria/patología , Biomarcadores de Tumor/análisis , Progresión de la Enfermedad , Femenino , Humanos , Inmunohistoquímica , Masculino , Clasificación del Tumor , Factores Protectores , Factores de Transcripción/análisis , Proteínas Supresoras de Tumor/análisis , Neoplasias de la Vejiga Urinaria/química
4.
Materials (Basel) ; 17(11)2024 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-38893791

RESUMEN

Elastic composites were prepared using a procedure involving hot plates and zinc powder that was directly dispersed into an EVA matrix. The correlation between the zinc content and the conductive properties of the material was studied via impedance spectroscopy, the thermal properties of the material were studied via differential calorimetry and the mechanical properties of the composites were studied via tensile strength curves, representing an important advancement in the characterization of this type of composite material. The composites' tensile strength and elongation at break decrease with the addition of filler since zinc particles act as stress-concentrating centres, while the composites' hardness and Young's modulus increase because of an increase in the stiffness of the material. The AC perturbation across the EVA/Zn composites was characterized using an RC parallel equivalent circuit that allowed us to easily measure their resistivity (ρp) and permittivity (εp). The dependence of these electrical magnitudes on the zinc content is correlated with their mechanical properties across the characteristic time constant τp = ρp·Îµp of this equivalent circuit. The dependence of the mechanical and electrical magnitudes on the zinc content is consistent with the formation of percolation clusters. The addition of graphite particles increases their potential performance. Three possible mechanisms for the electrical transport of the ac-perturbation across the EVA/Zn composites have been identified. Chemical corrosion in acid media causes the loss of zinc surface particles, but their bulk physical properties practically remain constant.

5.
Arch Ital Urol Androl ; 96(2): 12703, 2024 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-38934520

RESUMEN

AIM: To present state of the art on the management of urinary stones from a panel of globally recognized urolithiasis experts who met during the Experts in Stone Disease Congress in Valencia in January 2024. Options of treatment: The surgical treatment modalities of renal and ureteral stones are well defined by the guidelines of international societies, although for some index cases more alternative options are possible. For 1.5 cm renal stones, both m-PCNL and RIRS have proven to be valid treatment alternatives with comparable stone-free rates. The m-PCNL has proven to be more cost effective and requires a shorter operative time, while the RIRS has demonstrated lower morbidity in terms of blood loss and shorter recovery times. SWL has proven to be less effective at least for lower calyceal stones but has the highest safety profile. For a 6mm obstructing stone of the pelviureteric junction (PUJ) stone, SWL should be the first choice for a stone less than 1 cm, due to less invasiveness and lower risk of complications although it has a lower stone free-rate. RIRS has advantages in certain conditions such as anticoagulant treatment, obesity, or body deformity. Technical issues of the surgical procedures for stone removal: In patients receiving antithrombotic therapy, SWL, PCN and open surgery are at elevated risk of hemorrhage or perinephric hematoma. URS, is associated with less morbidity in these cases. An individualized combined evaluation of risks of bleeding and thromboembolism should determine the perioperative thromboprophylactic strategy. Pre-interventional urine culture and antibiotic therapy are mandatory although UTI treatment is becoming more challenging due to increasing resistance to routinely applied antibiotics. The use of an intrarenal urine culture and stone culture is recommended to adapt antibiotic therapy in case of postoperative infectious complications. Measurements of temperature and pressure during RIRS are vital for ensuring patient safety and optimizing surgical outcomes although techniques of measurements and methods for data analysis are still to be refined. Ureteral stents were improved by the development of new biomaterials, new coatings, and new stent designs. Topics of current research are the development of drug eluting and bioresorbable stents. Complications of endoscopic treatment: PCNL is considered the most invasive surgical option. Fever and sepsis were observed in 11 and 0.5% and need for transfusion and embolization for bleeding in 7 and 0.4%. Major complications, as colonic, splenic, liver, gall bladder and bowel injuries are quite rare but are associated with significant morbidity. Ureteroscopy causes less complications, although some of them can be severe. They depend on high pressure in the urinary tract (sepsis or renal bleeding) or application of excessive force to the urinary tract (ureteral avulsion or stricture). Diagnostic work up:  Genetic testing consents the diagnosis of monogenetic conditions causing stones. It should be carried out in children and in selected adults. In adults, monogenetic diseases can be diagnosed by systematic genetic testing in no more than 4%, when cystinuria, APRT deficiency, and xanthinuria are excluded. A reliable stone analysis by infrared spectroscopy or X-ray diffraction is mandatory and should be associated to examination of the stone under a stereomicroscope. The analysis of digital images of stones by deep convolutional neural networks in dry laboratory or during endoscopic examination could allow the classification of stones based on their color and texture. Scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) is another fundamental research tool for the study of kidney stones. The combination of metagenomic analysis using Next Generation Sequencing (NGS) techniques and the enhanced quantitative urine culture (EQUC) protocol can be used to evaluate the urobiome of renal stone formers. Twenty-four hour urine analysis has a place during patient evaluation together with repeated measurements of urinary pH with a digital pH meter. Urinary supersaturation is the most comprehensive physicochemical risk factor employed in urolithiasis research. Urinary macromolecules can act as both promoters or inhibitors of stone formation depending on the chemical composition of urine in which they are operating. At the moment, there are no clinical applications of macromolecules in stone management or prophylaxis. Patients should be evaluated for the association with systemic pathologies. PROPHYLAXIS: Personalized medicine and public health interventions are complementary to prevent stone recurrence. Personalized medicine addresses a small part of stone patients with a high risk of recurrence and systemic complications requiring specific dietary and pharmacological treatment to prevent stone recurrence and complications of associated systemic diseases. The more numerous subjects who form one or a few stones during their entire lifespan should be treated by modifications of diet and lifestyle. Primary prevention by public health interventions is advisable to reduce prevalence of stones in the general population. Renal stone formers at "high-risk" for recurrence need early diagnosis to start specific treatment. Stone analysis allows the identification of most "high-risk" patients forming non-calcium stones: infection stones (struvite), uric acid and urates, cystine and other rare stones (dihydroxyadenine, xanthine). Patients at "high-risk" forming calcium stones require a more difficult diagnosis by clinical and laboratory evaluation. Particularly, patients with cystinuria and primary hyperoxaluria should be actively searched. FUTURE RESEARCH: Application of Artificial Intelligence are promising for automated identification of ureteral stones on CT imaging, prediction of stone composition and 24-hour urinary risk factors by demographics and clinical parameters, assessment of stone composition by evaluation of endoscopic images and prediction of outcomes of stone treatments. The synergy between urologists, nephrologists, and scientists in basic kidney stone research will enhance the depth and breadth of investigations, leading to a more comprehensive understanding of kidney stone formation.


Asunto(s)
Cálculos Urinarios , Humanos , Cálculos Urinarios/terapia , Cálculos Urinarios/cirugía , Predicción
6.
MethodsX ; 10: 101952, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36636282

RESUMEN

Caprolactam is a highly useful monomer obtained through the Beckmann arrangement, which generates large profits worldwide and is widely used in different industries. During the synthesis process, various components can be generated that weaken the quality of the final product, to have control of the monomer, monitoring is carried out during the synthesis and characterization of the final product. These characterizations generally take time due to the different techniques that must be performed to obtain the data. In this work, a method is designed that associates different techniques to reduce the number of steps carried out in the tests to determine the quality of the material, optimize the times and generate a quality and efficient process in a shorter time, in addition, it is due to a semi-automated system for the simultaneous characterization of caprolactam, which, according to the statistical data obtained for sodium, iron, volatile bases, and moisture analysis were reproducible. The developed prototype had 21 on-line valves that allowed taking the representative volumes of samples and reagents necessary for each measurement. There is excellent linearity where the correlation coefficient has values between 0,9992 and 1. The values obtained for the relative error are between 0.18 and 2.24% for laboratory tests using the traditional method and between 0.21 and 3.83% for tests carried out using the prototype. The P value of the evaluation of the means was 0.997, indicating that the means are not statistically different.•Caprolactam analysis•Process optimization•Determination of impurities.

7.
Polymers (Basel) ; 15(16)2023 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-37631415

RESUMEN

In this study, formulations of thermoplastic starch (TPS) with 5, 10, and 15 parts per hundred resin (phr) of raw peach gum (PG) were prepared by melt extrusion followed by injection molding to obtain standard specimens for characterization. In addition, biodegradable films were developed by compression molding. It was determined that TPS with 5 phr and 10 phr of PG presented similar mechanical behavior to pure TPS after the processing. However, results indicated that adding PG in 10 phr slowed down the starch's retrogradation, delaying the TPS structure's stiffening. Moreover, the TPS-PG formulations presented improved solubility, which increased by 24% with 10 and 15 phr of PG compared to that shown for TPS. Additionally, PG enhanced the compostability of TPS, causing the sample to disintegrate in a shorter period. In conclusion, it was determined that raw PG added in 10 phr could be added as a sustainable additive to modify the biodegradation and water sensitivity of TPS without affecting its mechanical behavior after processing and delaying the retrogradation of the TPS structure, increasing its shelf life.

8.
Polymers (Basel) ; 15(5)2023 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-36904454

RESUMEN

Sea and environmental pollution due to microplastics are global problems that in recent years have attracted particular interest in the scientific community. The increase in the world population and the consequent consumerism of non-reusable materials are amplifying these problems. In this manuscript, we present novel bioplastics, which are completely biodegradable, for their potential use in food packaging, to replace fossil-fuel-derived plastic films and slow food degradation due to oxidative processes or microbial contamination. In this study, thin films based on polybutylene succinate (PBS) were prepared to reduce pollution, and different percentages by weight (1, 2 and 3 wt%) of extra virgin olive oil (EVO) and coconut oil (CO) were included to improve the chemico-physical properties of the polymer and possibly improve the functionality of the films in terms of prolonged food preservation. Attenuated total reflectance Fourier transform infrared (ATR/FTIR) spectroscopy was used to evaluate the interactions between the polymer and the oil. Furthermore, the mechanical properties and thermal behavior of the films were evaluated as a function of the oil content. A scanning electron microscopy (SEM) micrograph showed the surface morphology and the thickness of the materials. Finally, apple and kiwi were selected for a food-contact test, and the wrapped sliced fruit was monitored and evaluated for 12 days to macroscopically evaluate the oxidative process and/or eventually occurring contamination. The films were shown to reduce the browning of sliced fruit due to oxidation, and no molds were evidenced up to 10/12 days of observation with the addition of PBS, with 3 wt% of EVO achieving the best outcomes.

9.
Polymers (Basel) ; 14(13)2022 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-35808691

RESUMEN

This study evaluates the effect of CaCO3 fillers extracted from waste eggshells on 3D-printed PLA performance. Samples of neat PLA and PLA reinforced with CaCO3 fillers embedded with different wt.% were prepared using an FDM (fused deposition modeling) technology. The samples were examined using mechanical, dynamic mechanical, thermal, and thermal decomposition analyses. The results revealed increasing elastic moduli, tensile strength, and flexure as the filler content increased. The rheological results from the MFR tests showed that the filler content did not influence the PLA-based samples' processability. Further, the thermal degradation of neat and various CaCO3-wt.%-reinforced PLA specimens revealed relatively small discrepancies in their exposure to the temperature increase, mainly concerning the eggshell organic components and volatile components, from their processability up to 300 °C. By contrast, the increased filler content positively shifted the peaks along the temperature scale at the maximum degradation rate. Additionally, the weight content of the natural reinforcement strongly influenced the surface wettability and appearance of the samples. Further, the SEM analysis featured both the presence of interlayer disturbances and the interfacial compatibility the PLA with the selected fillers.

10.
Foods ; 10(6)2021 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-34071084

RESUMEN

Completely biobased and biodegradable thermoplastic starch (TPS) based materials with a tunable performance were prepared for food packaging applications. Five blends were prepared by blending TPS with 10 wt%. of different pine resins derivatives: gum rosin (GR), disproportionated gum rosin (RD), maleic anhydride-modified gum rosin (CM), pentaerythritol ester of gum rosin (LF), and glycerol ester of gum rosin (UG). The materials were characterized in terms of thermo-mechanical behavior, surface wettability, color performance, water absorption, X-ray diffraction pattern, and disintegration under composting conditions. It was determined that pine resin derivatives increase the hydrophobicity of TPS and also increase the elastic component of TPS which stiffen the TPS structure. The water uptake study revealed that GR and LF were able to decrease the water absorption of TPS, while the rest of the resins kept the water uptake ability. X-ray diffraction analyses revealed that GR, CM, and RD restrain the aging of TPS after 24 months of aging. Finally, all TPS-resin blends were disintegrated under composting conditions during the thermophilic incubation period (90 days). Because of the TPS-resin blend's performance, the prepared materials are suitable for biodegradable rigid food packaging applications.

11.
Polymers (Basel) ; 13(9)2021 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-34067087

RESUMEN

Mater-Bi® NF866 (MB) was blended with gum rosin and two pentaerythritol esters of gum rosin (labeled as LF and UT), as additives, to produce biobased and compostable films for food packaging or agricultural mulch films. The films were prepared by blending MB with 5, 10, and 15 wt.% of each additive. The obtained films were characterized by optical, colorimetric, wettability, and oxygen barrier properties. Moreover, the additives and the MB-based films were disintegrated under composting conditions and the effect of each additive on the biodegradation rate was studied. All films were homogeneous and optically transparent. The color of the films tended to yellow tones due to the addition of pine resin derivatives. All the formulated films presented a complete UV-transmittance blocking effect in the UVA and UVB region, and those with 5 wt.% of pine resin derivatives increased the MB hydrophobicity. Low amounts of resins tend to maintain the oxygen transmission rate (OTR) values of the neat MB, due to its good solubilizing and compatibilizing effects. The disintegration under composting conditions test revealed that gum rosin completely disintegrates in about 90 days, while UT degrades 80% and LF degrades 5%, over 180 days of incubation. As expected, the same tendency was obtained for the disintegration of the studied films, although Mater-Bi® reach 28% of disintegrability over the 180 days of the composting test.

12.
Polymers (Basel) ; 13(12)2021 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-34201407

RESUMEN

Gum rosin (GR) was used as a natural additive to improve the compatibility between polylactic acid, PLA, and poly(butylene adipate-co-terephthalate, PBAT, blended with 20 wt.% of PBAT (PLA/PBAT). The PBAT was used as a soft component to increase the ductility of PLA and its fracture toughness. The coalescence of the PBAT domains was possible due to the plasticization effect of the GR component. These domains contributed to increasing the toughness of the final material due to the variation and control of the PBAT domains' size and consequently, reducing the stress concentration points. The GR was used in contents of 5, 10, 15, and 20 phr. Consequently, the flexural properties were improved and the impact resistance increased up to 80% in PLA/PBAT_15GR with respect to the PLA/PBAT formulation. Field emission scanning electron microscope (FESEM) images allowed observing that the size of PBAT domains of 2-3 µm was optimal to reduce the impact stress. Differential scanning calorimetry (DSC) analysis showed a reduction of up to 8 °C on the PLA melting temperature and up to 5.3 °C of the PLA glass transition temperature in the PLA/PBAT_20GR formulation, which indicates an improvement in the processability of PLA. Finally, transparent films with improved oxygen barrier performance and increased hydrophobicity were obtained suggesting the potential interest of these blends for the food packaging industry.

13.
Arch Esp Urol ; 74(1): 63-70, 2021 Jan.
Artículo en Inglés, Español | MEDLINE | ID: mdl-33459622

RESUMEN

INTRODUCTION: Prevalence of urolithiasisis estimated between 5-15% with a clear trend to increasing in the industrialized countries. Stone recurrent patients show an increased risk of chronic renal disease which can potentially limit their life expectancy. OBJECTIVE: A review and summary of the different recommended treatment options to prevent urinary stone recurrence based on the type of calculi or urinary metabolic alterations in 24 h urine, according to recent guidelines and publications. CONCLUSIONS: Dietetic and pharmacologic measures, when addressed depending on the type of stone and results of metabolic evaluation have shown a decrease up to 60% of the recurrent clinical events. The increase of prevalence worldwide and the potential risk of chronic kidney disease in these patients clearly justify the need of increasing physiopathologic knowledge leading urolithiasis formation in order to develop new and more effective drugs for its prevention.


INTRODUCCIÓN: La prevalencia de lapatología litiásica se estima en un 5% al 15%, con unaclara tendencia al aumento en los países industrializados. Los pacientes con episodios recurrentes de litiasis renal presentan un riesgo aumentado de enfermedad renal crónica que puede potencialmente limitar su expectativade vida.OBJETIVO: Revisión y síntesis de las opciones terapéuticas recomendadas para la prevención en la recurrencia de cálculos urinarios basadas en el tipo de cálculo o alteración urinaria en orina de 24 horas, según las guías clínicas y publicaciones recientes.CONCLUSIONES: Medidas dietéticas y farmacológicas han demostrado una reducción de hasta el 60% en la recurrencia de episodios clínicos cuando son dirigidas según el tipo de cálculo y los resultados de los estudios metabólicos. El aumento en la prevalencia mundial de esta patología y el potencial riesgo de enfermedad renal crónica en pacientes recurrentes, justifican la necesidad de ampliar los conocimientos fisiopatológicos que precipitan la formación de litiasis urinarias para el desarrollo de nuevos tratamientos más eficaces en la prevención de esta enfermedad.


Asunto(s)
Cálculos Renales , Cálculos Urinarios , Urolitiasis , Humanos , Recurrencia , Urolitiasis/terapia
14.
Polymers (Basel) ; 12(1)2020 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-31963296

RESUMEN

The interaction between gum rosin and gum rosin derivatives with Mater-Bi type bioplastic, a biodegradable and compostable commercial bioplastic, were studied. Gum rosin and two pentaerythritol esters of gum rosin (Lurefor 125 resin and Unik Tack P100 resin) were assessed as sustainable compatibilizers for the components of Mater-Bi® NF 866 polymeric matrix. To study the influence of each additive in the polymeric matrix, each gum rosin-based additive was compounded in 15 wt % by melt-extrusion and further injection molding process. Then, the mechanical properties were assessed, and the tensile properties and impact resistance were determined. Microscopic analyses were carried out by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and atomic force microscopy with nanomechanical assessment (AFM-QNM). The oxygen barrier and wettability properties were also assayed. The study revealed that the commercial thermoplastic starch is mainly composed of three phases: A polybutylene adipate-co-terephthalate (PBAT) phase, an amorphous phase of thermoplastic starch (TPSa), and a semi-crystalline phase of thermoplastic starch (TPSc). The poor miscibility among the components of the Mater-Bi type bioplastic was confirmed. Finally, the formulations with the gum rosin and its derivatives showed an improvement of the miscibility and the solubility of the components depending on the additive used.

15.
Polymers (Basel) ; 12(2)2020 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-32033300

RESUMEN

In this work, different materials for three-dimensional (3D)-printing were studied, which based on polycaprolactone with two natural additives, gum rosin, and beeswax. During the 3D-printing process, the bed and extrusion temperatures of each formulation were established. After, the obtained materials were characterized by mechanical, thermal, and structural properties. The results showed that the formulation with containing polycaprolactone with a mixture of gum rosin and beeswax as additive behaved better during the 3D-printing process. Moreover, the miscibility and compatibility between the additives and the matrix were concluded through the thermal assessment. The mechanical characterization established that the addition of the mixture of gum rosin and beeswax provides greater tensile strength than those additives separately, facilitating 3D-printing. In contrast, the addition of beeswax increased the ductility of the material, which makes the 3D-printing processing difficult. Despite the fact that both natural additives had a plasticizing effect, the formulations containing gum rosin showed greater elongation at break. Finally, Fourier-Transform Infrared Spectroscopy assessment deduced that polycaprolactone interacts with the functional groups of the additives.

16.
Polymers (Basel) ; 12(11)2020 Oct 29.
Artículo en Inglés | MEDLINE | ID: mdl-33137961

RESUMEN

Poly(lactic acid) (PLA) was plasticized with maleinized linseed oil (MLO) and further reinforced with sheep wool fibers recovered from the dairy industry. The wool fibers were firstly functionalized with 1 and 2.5 phr of tris(2-methoxyethoxy)(vinyl) (TVS) silane coupling agent and were further used in 1, 5, and 10 phr to reinforce the PLA/MLO matrix. Then, the composite materials were processed by extrusion, followed by injection-molding processes. The mechanical, thermal, microstructural, and surface properties were assessed. While the addition of untreated wool fibers to the plasticized PLA/MLO matrix caused a general decrease in the mechanical properties, the TVS treatment was able to slightly compensate for such mechanical losses. Additionally, a shift in cold crystallization and a decrease in the degree of crystallization were observed due to the fiber silane modification. The microstructural analysis confirmed enhanced interaction between silane-modified fibers and the polymeric matrix. The inclusion of the fiber into the PLA/MLO matrix made the obtained material more hydrophobic, while the yellowish color of the material increased with the fiber content.

17.
Polymers (Basel) ; 12(12)2020 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-33276625

RESUMEN

Polybutylene adipate-co-terephthalate (PBAT) is a biodegradable polymer with good features for packaging applications. However, the mechanical performance and high prices of PBAT limit its current usage at the commercial level. To improve the properties and reduce the cost of PBAT, pine resin derivatives, gum rosin (GR) and pentaerythritol ester of GR (UT), were proposed as sustainable additives. For this purpose, PBAT was blended with 5, 10, and 15 wt.% of additives by melt-extrusion followed by injection moulding. The overall performance of the formulations was assessed by tensile test, microstructural, thermal, and dynamic mechanical thermal analysis. The results showed that although good miscibility of both resins with PBAT matrix was achieved, GR in 10 wt.% showed better interfacial adhesion with the PBAT matrix than UT. The thermal characterization suggested that GR and UT reduce PBAT melting enthalpy and enhance its thermal stability, improving PBAT processability. A 10 wt.% of GR significantly increased the tensile properties of PBAT, while a 15 wt.% of UT maintained PBAT tensile performance. The obtained materials showed higher hydrophobicity than neat PBAT. Thus, GR and UT demonstrated that they are advantageous additives for PBAT-resin compounding for rigid food packaging which are easy to process and adequate for industrial scalability. At the same time, they enhance its mechanical and hydrophobic performance.

18.
Materials (Basel) ; 13(3)2020 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-32012947

RESUMEN

The use of maleinized (MLO) and epoxidized (ELO) linseed oils as potential biobased plasticizers for lignin/natural fiber composites formulations with improved toughness was evaluated. Arboform®, a lignin/natural fiber commercial composite, was used as a reference matrix for the formulations. The plasticizer content varied in the range 0-15 wt % and mechanical, thermal and morphological characterizations were used to assess the potential of these environmentally friendly modifiers. Results from impact tests show a general increase in the impact-absorbed energy for all the samples modified with bio-oils. The addition of 2.5 wt % of ELO to Arboform (5.4 kJ/m2) was able to double the quantity of absorbed energy (11.1 kJ/m2) and this value slightly decreased for samples containing 5 and 10 wt %. A similar result was obtained with the addition of MLO at 5 wt %, with an improvement of 118%. The results of tensile and flexural tests also show that ELO and MLO addition increased the tensile strength as the percentage of both oils increased, even if higher values were obtained with lower percentages of maleinized oil due to the possible presence of ester bonds formed between multiple maleic groups present in MLO and the hydroxyl groups of the matrix. Thermal characterization confirmed that the mobility of polymer chains was easier in the presence of ELO molecules. On the other hand, MLO presence delayed the crystallization event, predominantly acting as an anti-nucleating agent, interrupting the folding or packing process. Both chemically modified vegetable oils also efficiently improved the thermal stability of the neat matrix.

19.
J Sep Sci ; 32(9): 1383-9, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19330790

RESUMEN

Di-(2-ethylhexyl)phthalate (DEHP) was determined in environmental samples such as water and soil. DEHP was extracted from water samples using SPE, whereas for soils pressurized liquid extraction was applied as extraction method, using hexane/acetone (1:1, v/v) as extractant solvent. The use of HPLC coupled to MS provides the basis of the selective determination of DEHP in the analyzed samples. The extraction procedures were validated and good results were found. Recoveries were ranged from 86.0 to 99.8% with RSD lower than 18% and LODs were 0.02 mg/kg and 0.03 microg/L for soils and water, respectively. Finally, the optimized methods were applied to the analysis of real samples and DEHP was not found above the LOQ (0.05 mg/kg) in soil samples whereas it was detected in water samples at concentrations ranging between 0.19 to 0.88 microg/L.

20.
Polymers (Basel) ; 11(9)2019 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-31533307

RESUMEN

A method to modify polymers is that of introducing fibers in a matrix to produce a fiber-reinforced polymer (FRP). Consequently, the aim of this work was to study the compatibility effect of four coupling agents on wool FRP properties, using poly(lactic acid) plasticized with maleinized linseed oil as polymer matrix. The content of wool assessed was 1 phr. The compatibilizers were (3-(2-aminoethylamino)propyl)-trimethoxysilane, trimethoxy (2-(7-oxabicyclo (4.1.0)hept-3-yl) ethyl) silane, tris(2-methoxyethoxy)(vinyl) silane and titanium (IV) (triethanolaminate)isopropoxide. Initially, wool was modified with coupling agents in an acetone/water (50/50) solution. Mechanical properties were evaluated by tensile and flexural properties, hardness by Shore D measurement and impact resistance by Charpy's energy. Differential scanning calorimetry, dynamic thermo-mechanical analysis, and thermogravimetric analysis were conducted to evaluate the interaction among components and the effect of the coupling agents on the thermal properties of the original material. Color, wettability and scanning electron microscopy were used to describe physical and microstructural properties. Modification of fibers allows achieving improved mechanical properties and changes the thermal properties of the FRPs slightly. Coupling agent treatment helps to formulate PLA-MLO and sheep wool materials and to improve their performance, thereby creating a broader spectrum of applications for PLA maintaining the bio-based character of the material.

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