ABSTRACT Focused on physically recycled poly(ethylene terephthalate) (rPET), the study sought to address the issues of crystallization and mechanical property degradation occurring in the mechanical recycling process by adding organic nucleating agents. The rPET/nucleating agent blends were prepared by the melt blending method, and the microstructure, crystal structure, crystallization, and mechanical properties of the nucleating agents and the blends were systematically studied. The results showed that the organic nucleating agent could react with rPET to form a new substance with ionic end groups. The differences in morphology of nucleating agents significantly affected the nucleation and crystal growth of rPET, and that lattice matching was the key mechanism to control the crystallization behavior. The nucleating agent matched with the rPET lattice could effectively induce the ordered arrangement of rPET molecular chains, significantly reduced the molecular chain rearrangement barrier and interfacial free energy, and then accelerated the nucleation rate. Compared with pure rPET, the flexural strength and notched impact strength of the rPET/nucleating agent blends increased by a maximum of 12.3% and 23.4%, respectively. The study broadened the applications of rPET in recycling by improving its material properties and provided a more practical material solution for the efficient promotion of the plastic recycling economy.

The nucleating agents with different alkyl chain lengths sodium 4-[(benzyl)amino] benzoate (SAB-Be), sodium 4-[(heptanoyl)amino] benzoate (SAB-7C), and sodium 4-[(stearoyl)amino] benzoate (SAB-18C) were synthesized via chemical to improve the crystallization and mechanical properties of recycled polyethylene terephthalate (rPET) that had been damaged during mechanical recycling. The rPET/nucleating agent blends were prepared by melt blending. The molecular structure and thermal stability of the nucleating agents were characterized using the utilization of fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The differential scanning calorimetry (DSC) results showed that the crystallization properties of the rPET had been improved. In addition, the glass transition temperatures (Tg) of rPET, rPET/SAB-Be, rPET/SAB-7C, and rPET/SAB-18C were 80.3 ± 0.3 °C, 80.4 ± 0.9 °C, 77.0 ± 1.2 °C, and 69.7 ± 0.9 °C, respectively, demonstrating that the length of the alkyl chain in the nucleating agents was essentially proportional to the lubrication effect on rPET. Meanwhile, the rheological properties also supported the conclusion. The isothermal thermodynamic analysis indicated that the compatibility between nucleating agents and rPET was related to the length of the alkyl chain in the nucleating agents. The scanning electron microscopy (SEM) results of the fracture surfaces of the rPET/nucleating agent blends showed that the longer the alkyl chain in the nucleating agent, the greater the compatibility with rPET. Furthermore, the rPET/SAB-18C exhibited the best mechanical properties of the samples used in this research, with flexural strength and impact strength increased by 5.1% and 58.9%, respectively, compared to rPET. Overall, this work provided the new approach for rPET upcycling by combining molecular design strategies.

The molecular chains of recycled polyethylene terephthalate (rPET) show breakage during daily use, causing poor crystallization and leading to mechanical properties that, when blended with the nucleating agent, become an effective method of solving this problem. The salt-nucleating agent sodium benzoate (SB), disodium terephthalate (DT), and trisodium 1,3,5benzene tricarboxylic (TBT) were synthesized, and an rPET/nucleating agent blend was prepared. The intrinsic viscosity (η) results showed that the η of the rPET/SB was decreased, which indicated the breakage of the rPET molecular chains. The FTIR results indicated that a chemical reaction occurred between the rPET and Na+ of the SB. Moreover, the Na+ content of the DT and TBT were higher than that of the SB, which increased the opportunity for low-molecular-weight rPET to reattach to the organic carboxylic acid portion of the nucleating agent, thereby increasing the η of the rPET/DT and rPET/TBT. The salt-nucleating agent sodium benzoate greatly improved the crystallization properties of the rPET, resulting in the half-crystallization time decreasing, the crystallization temperature increasing, and the effect of SB being better than that of DT and TBT. This was because the nucleating agent caused chemical nucleation with rPET, and the ionic groups acted as nucleation sites, while the rPET/DT and rPET/TBT, which had high molecular weights, hindered the improvement of the crystallization properties. The mechanical properties prove that the rPET/SB decreased due to the severe degradation of the rPET molecular chains. The mechanical properties of the rPET/DT and rPET/TBT were effectively improved because of the nucleating agent refining the grain size of the rPET and the high molecular weight. But the stacking of multitudinous rPET molecular chains can form a structure resembling physical cross-linking, causing a slight decrease in the mechanical properties of the rPET/TBT compared to the rPET/DT.

Among numerous nucleating agents, organic carboxylate nucleating agents have been demonstrated to markedly improve the crystallization of polypropylene (PP). However, poor dispersion in the PP matrix affects the modification effect. In this work, erucamide (ECM) and sodium 4-[(4-chlorobenzoyl) amino] benzoate (SCAB) form a hydrogen-bonded self-assembled structure to obtain the SCAB-ECM composite nucleating agent in order to improve the dispersion of SCAB in the PP matrix and to exert internal lubrication on the PP matrix. The molecular structure of the SCAB-ECM composite was investigated by using Fourier transform infrared spectroscopy (FT-IR), and the result showed that SCAB and ECM could form a hydrogen-bonded self-assembled structure after physical blending. The scanning electron microscopy (SEM) results visualized that ECM promoted the dispersion of SCAB due to the formation of hydrogen-bonded self-assembled structures by SCAB and ECM. The crystallization behavior was studied using differential scanning calorimetry (DSC). At the crystallization temperature of 135 °C, the K of PP, PP/ECM, PP/SCAB, and PP/SCAB-ECM were 0.0002, 0.0004, 1.1616, and 1.8539, respectively. The crystallization properties of PP/SCAB-ECM were the best, which was attributed to the fact that SCAB formed a hydrogen-bonded self-assembled structure with ECM, which promoted the dispersion of SCAB in the PP matrix. The results of the rheological behavior demonstrated that the ECM can act as a lubrication effect, which was also proved by flexural strength results.

To solve the decrease in the crystallization, mechanical and thermal properties of recycled polyethylene terephthalate (rPET) during mechanical recycling, the aromatic amide fatty acid salt nucleating agents Na-4-ClBeAmBe, Na-4-ClBeAmGl and Na-4-ClAcAmBe were synthesized and the rPET/nucleating agent blend was prepared by melting blending. The molecular structure, the thermal stability, the microstructure and the crystal structure of the nucleating agent were characterized in detail. The differential scanning calorimetry (DSC) result indicated that the addition of the nucleating agent improved the crystallization temperature and accelerated the crystallization rate of the rPET. The nucleation efficiencies (NE) of the Na-4-ClBeAmBe, Na-4-ClBeAmGl and Na-4-ClAcAmBe were increased by 87.2%, 87.3% and 41.7% compared with rPET which indicated that Na-4-ClBeAmBe and Na-4-ClBeAmGl, with their long-strip microstructures, were more conducive to promoting the nucleation of rPET. The equilibrium melting points (Tm0) of rPET/Na-4-ClBeAmBe, rPET/Na-4-ClBeAmGl and rPET/Na-4-ClAcAmBe were increased by 11.7 °C, 18.6 °C and 1.9 °C compared with rPET, which illustrated that the lower mismatch rate between rPET and Na-4-ClBeAmGl (0.8% in b-axis) caused Na-4-ClBeAmGl to be the most capable in inducing the epitaxial crystallization and orient growth along the b-axis direction of the rPET. The small angle X-ray diffraction (SAXS) result proved this conclusion. Meanwhile, the addition of Na-4-ClBeAmGl caused the clearest increase in the rPET of its flexural strength and heat-distortion temperature (HDT) at 20.4% and 46.7%.

In this work, a novel α-nucleating agent (NA) for polypropylene (PP) termed APAl-3C-12Li was prepared and evaluated compared with the commercially available type NA-21. For the synthesis of the organophosphate-type NA (APAl-3C), the -OH group of the acid part of NA-21 was substituted by the isopropoxy group. The structure of APAl-3C was analyzed by spectroscopy and element analysis, the results of which were consistent with the theoretical molecular formula. APAl-3C’s thermal stability was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG), which showed only weak mass loss below 230 °C, meaning that it would not decompose during the processing of PP. The APAl-3C-12Li was used as a novel nucleating agent, studying its effects on crystallization, microstructure, mechanical and optical properties. Tests were performed in a PP random copolymer at different contents, in comparison to the commercial NA-21. The composite with 0.5 wt% APAl-3C-12Li has a similar crystallization temperature of 118.8 °C as with the addition of 0.5 wt% NA-21. An advantage is that the composite with the APAl-3C-12Li has a lower haze value of 9.3% than the counterpart with NA-21. This is due to the weaker polarity of APAl-3C-12Li after the introduction of methyl and better uniform dispersion in the PP matrix, resulting in stronger improvement of optical and mechanical properties.

Combining targeted therapy and immunotherapy brings hope for a complete cancer cure. Due to their selective colonization and immune activation capacity, some bacteria have the potential to realize targeted immunotherapy. Herein, a biohybrid system was designed and synthesized by cladding NO3--intercalated cobalt aluminum layered double hydroxides (LDH) on anaerobic Propionibacterium acnes (PA) (PA@LDH). In this system, the covering of LDH reduces the pathogenicity of PA to normal tissues and alters its surface charge for prolonged in vivo circulation. Once the tumor site is reached, the acid-responsive degradation of LDH enables PA exposure. PA can colonize and convert nitrate ions to nitric oxide (NO) through denitrification. Then, NO reacts with intracellular O2·- to produce toxic reactive nitrogen species ONOO- and induce tumor cell apoptosis. In addition, cobalt ions released from LDH can inhibit the activity of superoxide dismutase (SOD), thus increasing the level of O2·- and further enhancing the antitumor effect. Moreover, PA exposure activates M2-to-M1 macrophage polarization and a range of immune responses, thereby achieving a sustained antitumor activity. In vitro and in vivo results reveal that the biohybrid system eliminates solid tumors and inhibits tumor metastasis effectively. Overall, the biohybrid strategy provides a new avenue for realizing simultaneous immunotherapy and targeted therapy.

In this work, a kind of aryl phosphate salt nucleating agent (APAl-12C) was synthesized, which was replaced in the hydroxyl group on the aluminum hydroxy bis [2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate] (APAl-OH) by lauroyloxy, which could improve the dispersion between the nucleating agent and the iPP matrix and reduce the migration potential of the nucleating agent in the iPP matrix by increasing the molecular weight. The structure of the nucleating agent APAl-12C was analyzed by fourier infrared spectroscopy (FT-IR ) and 1H NMR. The differential scanning calorimeter (DSC) results indicated that the addition of APAl-OH or APAl-12C alone was inferior to the commercial nucleating agent NA-21 (compounds of APAl-OH and Lithium laurate) in terms of the crystallization behavior, which may be due to the importance of metal Li in the crystallization property. Thus, the iPP/A12C-Li composites were prepared with APAl-12C, lithium laurate (lilaurate) and the iPP matrix. The crystallization behavior, morphology, optical and mechanical properties for the iPP/A12C-Li composites were systematically studied and compared with that of the iPP/NA-21 composite. Among the iPP/A12C-Li composites with the addition of 0.5 wt%, APAl-12C/Lilaurate had the fastest crystallization rate and reduced the haze value of the neat iPP from 36.03% to 9.89% without changing the clarity, which was better than that of the iPP/NA-21 composite. This was due to the weakening of the polarity of the APAl-12C after lauroyloxy substitution and better dispersion in the iPP matrix, resulting in a significant improvement in the optical properties.

Isotactic polybutene (iPB) has a wide application in the water pipe field. However, the most valuable form I, needs 7 days to complete the transformation. In this study, the attapulgite (ATP), which produces lattice matching of the iPB form I, was selected to prepare an iPB/ATP composite. The Fischer–Tropsch wax (FTW) was grafted with maleic anhydride to obtain MAFT, and the ATP structure was reset by reactions with MAFT to the prepared FATP, which improved the interface compatibility of the ATP and iPB. The Fourier transform infrared spectroscopy (FT-IR) and the water contact angle test confirmed the successful synthesis of FATP. X-ray diffraction (XRD) verified that the graft of MAFT did not affect the crystal structure of ATP. The iPB + 5% FATP had the maximum flexural strength, which was 12.45 Mpa, and the flexural strength of the iPB + 5% FATP annealing for 1 day was much higher than others. Scanning electron microscope (SEM) photographs verified that FATP and iPB had good interface compatibility. The crystal transformation behavior indicated that the iPB + 5% FATP had the fastest crystal transformation rate, which proved that the reset structure, ATP, greatly accelerated the crystal transformation of iPB. This was a detailed study on the effect of lattice matching, interfacial compatibility and internal lubrication of the reset structure, ATP, in the nucleation and growth stages of iPB form I. The result was verified by XRD, differential scanning calorimetry (DSC), Avrami kinetics and polarizing microscope (POM) analysis.

Isotactic poly (1-butene) (iPB) has excellent properties which are recognized as a green and energy saving product. However, the most stable and valuable crystal form I had a spontaneous transformation that took as long as seven days to complete. As a special solid waste, the herb residue (HR) is rich in cellulose which has great potential to accelerate the crystal transformation of the iPB. However, the polarity of HR results in the interface compatibility with non-polar iPB. In this study, the HR was modified by silane coupling agent (KH570) to obtain KHR and the iPB/HR composite was prepared. The FTIR spectrum was indicated that the organic functional groups of KH570 successfully graft onto the surface of HR and the water contact angle test was indicated that the hydrophilicity of the KHR was greatly decreased. The complete crystal transformation time is 7 days for iPB, 6 days for iPB+5% HR but only 3 days for iPB+5% KHR. The addition of the HR and KHR improve the thermal stability of the composite and this beneficial effect is more obvious for KHR. After annealing for 5 days, the physical properties value include tensile strength, flexural strength, and HDT of iPB+5% HR reach that of pure iPB after annealing for 7 days, but only 3 days for iPB+5% KHR. The TG analysis and SEM photographs give clear evidence that the beneficial effect of KH570 modified HR on improving the interface compatibility with iPB.

Most of natural water-soluble polymers are difficult to electrospin due to their specific chain conformation in aqueous solution, which limits their applications. This study investigated the effects of polyethylene oxide (PEO) on the electrospinning of hyaluronic acid (HA) in HA/PEO aqueous solutions. The rheological properties of HA/PEO aqueous solutions showed polymer chain entanglement in HA was the essential factor affecting its electrospinnability. Wide-angle X-ray scattering and differential scanning calorimetry analyses of a PEO crystal showed different crystallization behavior of the PEO chain with different molecular weight, which indicates different interaction with HA. A schematic molecular model has been proposed to explain the effect of PEO on the chain conformation of HA along with the relationship between electrospinnability and chain entanglement. PEO with a relatively high molecular weight with limited crystal formation formed extensive chain entanglements with HA, while PEO with relatively low molecular weight weakened the interactions among HA chains. The findings of this study provide a wide perspective to better understand the electrospinning mechanisms of natural polyelectrolytes and usage in tissue engineering.

Isotactic polybutylene-1 (iPB) has lots of advantages and is best used as hot water pipe. However, to transform into stable crystal form I, the iPB needs as long as 7 days. In this process, the irreversible damage brings great difficulties to the use of the iPB. The method which convert it directly into crystal I has shortcomings such as being requiring complex operation and being expensive. In this study, an innovative idea was put forward, not paying attention to the crystal transformation of iPB but only focusing on reducing the time it can be applied. In this study, bamboo powder was modified by the silane coupling agent KH570 (KBP) to prepare iPB/KBP composite. The infiltration test and Fourier transform infrared (FTIR) analysis showed that the hydrophilicity of KBP is greatly reduced, which can greatly improve the compatibility of the iPB and KBP. The tensile strength, tensile modulus, flexural strength, and flexural modulus of the composites storage for 3 days is equal to the pure iPB with storage 7 days with the KBP additions of 3%, 3%, 7%, and 5%, respectively. The heat deformation temperature (HDT) of the composite with 3% KBP after 1-day storage reached the value of pure iPB storage for 7 days. This provides more space and possibilities for the industrialization of the iPB. The crystallization behavior of iPB/KBP composites proves that the addition of KBP accelerates the crystallization rate of iPB, but the crystallinity of the iPB/KBP composites is not changed. The SEM photograph of iPB/KBP composites showed that when the KBP addition was low the compatibility between KBP and iPB was good. When the KBP addition was increased the agglomeration of KBP in the iPB was very obvious, which leads to the poor mechanical properties of the composite.

Isotactic polypropylene (iPP) is a commonly used thermoplastic polymer with many excellent properties. But high brittleness, especially at low temperatures, limits the use of iPP. The presence of transcrystallization of iPP makes it possible for fiber-reinforced iPP composites with higher strength. Bacterial cellulose (BC) is a kind of cellulose with great potential to be used as a new filler to reinforce iPP due to its high crystallinity, biodegradability and efficient mechanical properties. In this study, the iPP/BC hamburger composite was prepared by a simple hot press and maleic anhydride grafted polypropylene (MAPP) was used to improve the interface compatibility of iPP and BC. The polarizing microscope (POM) photograph shows that BC successfully induces the transcrystallization of iPP. The differential Scanning Calorimeter (DSC) date proves that the addition of BC could improve the thermal properties and crystallization rate of the composite. Especially, this change is more obvious of the iPP/MAPP/BC. The mechanical properties of the iPP/BC composites were greatly increased. This DSC date is higher than BC; we used BC particles to enhance the iPP in our previous research. The scanning Electron Microscope (SEM) analysis intuitively shows that the interface of the iPP/MAPP/BC is more smooth and flat than the iPP/BC. The fourier Transform infrared spectroscopy (FT-IR) analysis of the iPP/BC hamburger composites was shown that a new C=O group vibration appeared at 1743 cm−1, which indicated that the hydrogen bond structure of BC molecules was weakened and some hydroxyl groups were substituted after modification which can increase the lipophilicity of BC. These results indicated that the BC fiber can easily induce the transcrystallization of iPP, which has excellent mechanical properties. Moreover, the addition of MAPP contributes greatly to the interface compatibility of iPP and BC.

To optimize the extraction technology for total flavonoids from Rose roxburghii. According to the re-sults of the single-factor experiment and the central composite experimental design principles,a response sur-face methodology which had three factors and three levels was designed to optimize the extraction technology for total flavonoids form Rose roxburghii.The effect of different drying methods(drying under the sun,drying in the shade,oven drying,microwave drying and freeze drying)on extraction rate was analyzed comparatively under the optimal conditions.The extraction rate of total flavonoids at 10.76 % was achieved under the optimal conditions:65 % ethanol was used as extraction solvent with the ratio of 1:71(g/mL)raw material to liquid,the reflux ex-traction time was 115.5 min.

Microcrystalline cellulose (MCC) offers great potential to improve the mechanical and crystallization properties of isotactic polybutene-1 (iPB) because of its low cost, biodegradability, renewability and excellent mechanical properties. However, the compatibility of polar MCC and non-polar iPB is poor. In this study, maleic anhydride grafted polybutene (MAPB) was prepared by the solution method and was used as a compatibilizer in the fabrication of iPB/MCC composites by using a twin screw extruder. The ultimate tensile strength, tensile modulus, flexural strength, flexural modulus of the iPB/MCC composites increased by 3.1%, 16.5%, 10.7%, 6.5%, respectively, compared with that of pure iPB. With MAPB addition, these values increased by 17.2%, 31%, 17.5% and 10%, respectively, compared with that of pure iPB. The heat-distortion temperature and thermal-decomposition temperature of all composites increased with an increased MCC content. The non-isothermal crystallization of the iPB/MCC composites shows that MCC addition can promote iPB crystallization, because the non-isothermal crystallization curve of the composites moves toward a higher temperature, especially after MAPB addition. Scanning electron micrographs indicate that the compatibility of the iPB/MCC has been enhanced significantly.

The application of near infrared spectroscopy for quantitative analysis of cotton-polyester textile was investigated in the present work. A total of 214 cotton-polyester fabric samples, covering the range from 0% to 100% cotton were measured and analyzed. Partial least squares and least-squares support vector machine models with all variables as input data were established. Furthermore, successive projection algorithm was used to select effective wavelengths and establish the successive projection algorithm-least-squares support vector machine models, with the comparison of two other effective wavelength selection methods: loading weights analysis and regression coefficient analysis. The calibration and validation results show that the successive projection algorithm-least-squares support vector machine model outperformed not only the partial least squares and least-squares support vector machine models with all variables as inputs, but also the least-squares support vector machine models with loading weights analysis and regression coefficient analysis effective wavelength selection. The root mean squared error of calibration and root mean squared error of prediction values of the successive projection algorithm-least-squares support vector machine regression model with the optimal performance were 0.77% and 1.17%, respectively. The overall results demonstrated that near infrared spectroscopy combined with least-squares support vector machine and successive projection algorithm could provide a simple, rapid, economical and non-destructive method for determining the composition of cotton-polyester textiles.

Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2.

ABSTRACT Accurate and rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) is needed to screen MRSA carriers and improve treatment. The current widely used duplex PCR methods are not able to differentiate MRSA from coexisting methicillin-susceptible S. aureus (MSSA) or other methicillin-resistant staphylococci. In this study, we aimed to develop a direct method for accurate and rapid detection of MRSA in clinical samples from open environments, such as nasal swabs. The new molecular assay is based on detecting the cooccurrence of nuc and mecA markers in a single bacterial cell by utilizing droplet digital PCR (ddPCR) with the chimeric lysin ClyH for cell lysis. The method consists of (i) dispersion of an intact single bacterium into nanoliter droplets, (ii) temperature-controlled release of genomic DNA (gDNA) by ClyH at 37°C, and (iii) amplification and detection of the markers (nuc and mecA) using standard TaqMan chemistries with ddPCR. Results were analyzed based on MRSA index ratios used for indicating the presence of the duplex-positive markers in droplets. The method was able to achieve an absolute limit of detection (LOD) of 2,900 CFU/ml for MRSA in nasal swabs spiked with excess amounts of Escherichia coli, MSSA, and other mecA-positive bacteria within 4 h. Initial testing of 104 nasal swabs showed that the method had 100% agreement with the standard culture method, while the normal duplex qPCR method had only about 87.5% agreement. The single-bacterium duplex ddPCR assay is rapid and powerful for more accurate detection of MRSA directly from clinical specimens.

To improve the mechanical performance of isotactic polypropylene (iPP), the iPP/bacterial cellulose (BC) composites were prepared. The tensile and impact strength of the composites were maximized (38.21 MPa and 2.812 KJ/m(2)) when maleic anhydride grafted polypropylene (MAPP) content was 7 wt%, the tensile modulus was increased with the higher MAPP content and the maximum value was 1858.39 MPa. Compared with pure iPP, the tensile strength, impact strength and tensile modulus increased by 6.32 MPa, 0.75 KJ/m(2), and 279.68 MPa, respectively. Compared with the control group (the sample which added BC but no MAPP added), the tensile strength, impact strength and tensile modulus increased by 5.61 MPa, 0.692 KJ/m(2), and 11.24 MPa, respectively. Moreover, the elongation at break of the composites was decreased. Besides, the rheological results and SEM photographs indicated that with the addition of MAPP, the compatibility of the composites was improved greatly, which demonstrated the increase of the mechanical properties of the composites.

Bacterial cellulose (BC) has great potential to be used as a new filler in reinforced isotactic polypropylene (iPP) due to its characteristics of high crystallinity, biodegradability and efficient mechanical properties.