RESUMEN
Fatty acid cellulose esters (FACE) are common cellulose-based thermoplastics, and their thermoplasticity is determined by both the contents and the lengths of the side chains. Herein, various FACE were synthesized by the ball-milling esterification of cellulose and fatty acyl chlorides containing 10-18 carbons, and their structures and thermoplasticity were thoroughly studied. The results showed that FACE with high degrees of substitution (DS) and low melting flow temperatures (Tf) were achieved as the chain lengths of the fatty acyl chlorides were reduced. In particular, a cellulose decanoate with a DS of 1.85 and a Tf of 186 °C was achieved by feeding 3 mol of decanoyl chloride per mole anhydroglucose units of cellulose. However, cellulose stearate (DS = 1.53) synthesized by the same protocols cannot melt even at 250 °C. More interestingly, the fatty acyl chlorides with 10 and 12 carbons resulted in FACE with superior toughness (elongation at break up to 94.4%). In contrast, due to their potential crystallization of the fatty acyl groups with 14-18 carbons, the corresponding FACE showed higher tensile strength and Young's modulus than the others. This study provides some theoretical basis for the mechanochemical synthesis of thermoplastic FACE with designated properties.
Asunto(s)
Cloruros , Ésteres , Ésteres/química , Estudios de Factibilidad , Esterificación , Celulosa/químicaRESUMEN
Primary hepatic stromal tumours are very rare and there are only sporadic reports in the literature. Due to the lack of specificity in their clinical manifestations and imaging features, these tumours are easily misdiagnosed. This current report presents a case of primary liver stromal tumour that was misdiagnosed as a liver cyst. The 72-year-old male patient was admitted to the hospital due to right upper abdomen fullness and discomfort for more than 2 weeks. Colour Doppler ultrasonography and enhanced computed tomography examinations revealed a cystic mass in the right lobe of the liver. The preoperative diagnosis was a liver cyst and the laparoscopic fenestration was performed. The pathological examination demonstrated that it was a primary hepatic stromal tumour. Gastroenteroscopy was performed postoperatively and no lesions were found in the gastrointestinal tract. Imatinib mesylate was given orally as the salvage therapy and a radical operation was planned at the patient's request. This current case serves as a reminder that clinicians should consider the possibility that it could be a primary hepatic stromal tumour rather than a hepatic cyst. A multidisciplinary team is necessary for the diagnosis and treatment of patients with a primary hepatic stromal tumour.
Asunto(s)
Quistes , Hepatopatías , Anciano , Quistes/diagnóstico por imagen , Quistes/cirugía , Errores Diagnósticos , Humanos , Hepatopatías/diagnóstico , Hepatopatías/cirugía , MasculinoRESUMEN
Cellulose is an abundant feedstock with renewability and biodegradability. However, it is still challenging to manufacture natural cellulose products by environmentally friendly thermoplastic processing methods. Herein, we proposed a green approach for the heterogeneous preparation of thermoplastic cellulose grafted polyurethane (RCP-g-PU) from amorphous regenerated cellulose paste (RCP) via hydroxyl/isocyanate chemistry. First, amorphous RCP was fabricated through dissolving cellulose in sodium hydroxide aqueous solution and regenerating in polyethylene glycol, resulting in the enhancement of the accessibility of hydroxy groups in cellulose chains. Subsequently, a series of thermoplastic RCP-g-PU with the melt flow temperatures ranging from 160 °C to 226 °C were feasibly synthesized by adding hexamethylene diisocyanate into RCP without using other organic solvents. Eventually, the resultant RCP-g-PU can be directly hot-pressed into transparent films with flexibility and foldability. The reported methodology represents a sustainable route to achieve thermoplastic cellulose derivatives.