Investigation on β‐polypropylene/PP‐g‐MAH/ surface‐treated calcium carbonate composites

β‐Polypropylene composites containing calcium carbonate treated by titanate coupling agent (T‐CaCO₃) and maleic anhydride grafted PP (PP‐g‐MAH) were prepared by melt compounding. The crystallization, morphology and mechanical properties of the composites were investigated by means of differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized light microscopy, scanning electron microscopy and mechanical tests. It is found that both T‐CaCO₃ and NT‐C are able to induce the formation of β‐phase, and NT‐C greatly increases the β content and decreases the spherulitic size of PP. PP‐g‐MAH facilitates the formation of β‐form PP and improves the compatibility between T‐CaCO₃ and PP. Izod notched impact strength of β‐PP/T‐CaCO₃ composite is higher than that of PP/T‐CaCO₃ composite, indicating the synergistic toughening effect of T‐CaCO₃ and β‐PP. Incorporation of PP‐g‐MAH into β‐PP/T‐CaCO₃ composite further increases the content of β‐crystal PP and improves the impact strength and tensile strength when T‐CaCO₃ concentration is below 5 wt%. The nonisothermal crystallization kinetics of β‐PP composites is well described by Jeziorny's and Mo's methods. It is found that NT‐C and T‐CaCO₃ accelerate the crystallization rate of PP but the influence of PP‐g‐MAH on crystallization rate of β‐PP composite is marginal. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation of Nano‐Sized Copper β‐Resorcylate (β‐Cu) and its Excellent Catalytic Activity for the Thermal Decomposition of Ammonium Perchlorate

Copper β‐resorcylate (cupric 2,4‐dihydroxy‐benzoate, β‐Cu) nanoparticles were prepared at a large‐scale via a facile wet mechanical grinding method and vacuum freeze‐drying process. The as‐prepared β‐Cu nanoparticles were characterized by powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier‐transform infrared spectroscopy (FT‐IR). The results revealed that the nano‐sized β‐Cu is of semi‐spherical shape and of homogeneous distribution, with a fairly uniform size of 100 nm. The formation mechanism of β‐Cu nanoparticles in the whole process was discussed in detail. Furthermore, the catalytic properties of as‐obtained β‐Cu were investigated. The TG/DSC study showed that nano‐sized β‐Cu could be a promising additive for accelerating the thermal decomposition of ammonium perchlorate (AP).     

Poly(ε‐caprolactone) composites containing gentamicin‐loaded β‐tricalcium phosphate/gelatin microspheres as bone tissue supports

In this work, novel antibacterial composites were prepared by using poly(ε‐caprolactone) (PCL) as the main matrix material, and gentamicin‐loaded microspheres composed of β‐tricalcium phosphate (β‐TCP) and gelatin. The purpose is to use this biodegradable material as a support for bone tissue. This composite system is expected to enhance bone regeneration by the presence of β‐TCP and prevent a possible infection that might occur around the defected bone region by the release of gentamicin. The effects of the ratio of the β‐TCP/gelatin microspheres on the morphological, mechanical, and degradation properties of composite films as well as in vitro antibiotic release and antibacterial activities against Escherichia coli and Staphylococcus aureus were investigated. The results showed that the composites of PCL and β‐TCP/gelatin microspheres had antibacterial activities for both bacteria. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Mechanical properties and densification behavior of β‐spodumene/anorthite composites

Although β‐spodumene/anorthite composites are interesting systems, little research work has been done to study their properties. This study aims at investigating the preparation and properties of β‐spodumene/anorthite composites containing β‐spodumene proportions ranging between 10 and 25 mass %. X‐ray diffraction analysis (XRD), Scanning electron microscopy (SEM), and the coefficient of thermal expansion (CTE) were used to characterize the effect of addition of β‐spodumene on the phase relations, microstructure, and thermal expansion behavior of resultant composites. The results show that the presence of β‐spodumene significantly reduces the porosity and reduces the densification temperature. It reduces thermal expansion and enhances the mechanical properties of anorthite‐containing composites.     

Permanent fixation of β‐cyclodextrin on cotton surface—An assessment between innovative and established approaches

Attachment of β‐cyclodextrin (β‐CD) molecules on cotton textile provides hosting cavities that can include a large variety of guest molecules for specific functionality. Five different new and existing techniques were evaluated for connecting β‐CD and its derivatives to cotton surface. A comparison has been made in terms of maximum attachment of β‐CD on cotton surface. Novel chemical based crosslinking with homo‐bi‐functional reactive dye (C.I. reactive black 5) and grafting with reactive monochlorotriazinyl‐β‐cyclodextrin show maximum attachment to cotton surface. Innovative, enzymatic coupling of especially synthesized 6‐monodeoxy‐6‐mono(N‐tyrosinyl)‐β‐cyclodextrin was performed on cotton textile surface. Enzymatic coupling was also carried out in a homogeneous system and attachment confirmed by UV–vis spectroscopy. This tyrosinase mediated coupling is low temperature and very specific technique. A phenolphthalein based analytical method was partially modified to reliably measure the amount of attached β‐CD on cotton surface. Atomic force microscopy and scanning electron microscopy techniques were used for surface characterization of the treated and untreated cotton surfaces. Alteration in surface topography has been observed for β‐CD treated samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Quantification of shish–kebab and β‐crystal on the mechanical properties of polypropylene

The oriented “shish–kebab” structure and β‐crystal can enhance the mechanical properties of polypropylene products. In this regard, equipment and β‐nucleation agents have been developed or modified to form shish–kebab and β‐crystal. However, the effect of shish–kebab/β‐crystal proportion on the mechanical properties of polypropylene remains unclear. The answer is crucial but remains a challenge because of the difficulty in manipulating the shish–kebab proportion. In this work, we used a self‐made multiflow vibrate‐injection molding, which can provide a controllable shear flow, to produce samples with different shear‐layer thicknesses. The shish–kebab proportion was represented by R, which is the thickness ratio of the shear layer to that of the whole sample. Results showed that the tensile strength exponentially increased, whereas the elongation at break exponentially decreased, with R. The impact strength remained constant with R, indicating that the shish–kebab and β‐crystal possessed similar toughening effects. This work proposes a schematic to interpret the strengthening mechanism involved and presents a method of establishing and controlling the mechanical properties of polypropylene samples by using shish–kebab structures and β‐crystals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45052.     

Preparation and Antibacterial Activities of Porous Silver‐doped β‐Tricalcium Phosphate Bioceramics

Infection is still a major concern in bone implants, especially in the implants with porous structures. As silver shows superior and broad‐spectrum antibacterial activity, porous silver‐doped β‐tricalcium phosphate (β‐TCP) bioceramics are prepared with 5% and 10% nanometer silver. The bioceramics show similar porous macrostructure with pure β‐TCP bioceramic, except slightly color change. They have almost identical microstructure to its pure β‐TCP counterpart under field emission scanning electron microscope. Their physical, chemical, and mechanical properties were investigated with X‐ray diffraction, Fourier transforming infrared spectrometer, and AG‐5kN, and no significant difference has been found between silver‐doped β‐TCP bioceramics and pure β‐TCP bioceramic. Bactericidal concentration of silver ions was detected in the solution soaked with the bioceramics. They can efficiently inhibit the growth of Staphylococcus epidermidis and Styphylococcus aureus, but show no cytotoxicity to L929 cells. It suggests that silver‐doped β‐TCP bioceramics can be developed into new type of bone substitutes with anti‐infection properties.     

Nonisothermal crystallization and multiple melting behaviors of β‐nucleated impact‐resistant polypropylene copolymer

As a substitute of isotactic polypropylene in applications requiring excellent fracture resistance, impact‐resistant polypropylene copolymer (IPC) has attracted much attention in recent years. In this study, a highly effective β‐form nucleating agent (β‐NA; an aryl amide compound) was introduced into IPC, and our attention was focused on the nonisothermal crystallization and subsequent melting behaviors of the nucleated samples. The nonisothermal crystallization behaviors were investigated on the basis of the different cooling rates and different concentrations of β‐NA with differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), and polarized optical microscopy. The results show that both the cooling rate and concentration of β‐NA greatly determined the nonisothermal crystallization process and subsequent multiple melting behaviors. Further results show that the multiple melting behaviors were related to the transition in β crystallites and those between the β and α crystallites. The morphologies of the dispersed particles and the supermolecular structure of the matrix were characterized with scanning electron microscopy. Finally, the effect of the β‐NA concentration on the fracture resistance of IPC was evaluated by measurement of the notched Izod impact strength. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A novel β‐nucleating agent for isotactic polypropylene

The nucleating ability of p‐cyclohexylamide carboxybenzene (β‐NA) towards isotactic polypropylene (iPP) was investigated by differential scanning calorimetry, X‐ray diffraction, polarized optical microscopy and scanning electron microscopy. β‐NA is identified to have dual nucleating ability for α‐iPP and β‐iPP under appropriate kinetic conditions. The formation of β‐iPP is dependent on the content of β‐NA. The content of β‐phase can reach as high as 96.96% with the addition of only 0.05 wt% β‐NA. Under non‐isothermal crystallization the content of β‐iPP increases with increasing cooling rate. The maximum β‐crystal content is obtained at a cooling rate of 40 °C min^–1. The supermolecular structure of the β‐iPP is identified as a leaf‐like transcrystalline structure with an ordered lamellae arrangement perpendicular to the special surface of β‐NA. Under isothermal crystallization β‐crystals can be formed in the temperature range 80–140 °C. The content of β‐crystals reaches its maximum value at a crystallization temperature of 130 °C. © 2012 Society of Chemical Industry     

Melting and crystallization behaviors,morphology, and mechanical properties of β‐polypropylene/polypropylene‐graft‐maleic anhydride/calcium sulfate whisker composites

The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface‐treated calcium sulfate (CaSO₄) whisker (T‐CSW), β‐PP/T‐CSW, and β‐PP/polypropylene‐graft‐maleic anhydride (PP‐g‐MAH)/T‐CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T‐CSW was an α‐nucleating agent and increased the crystallization temperatures of PP, but PP‐g‐MAH and high loadings of T‐CSW had weakly negative effects on the crystallization rates of PP. The T‐CSW restrained the formation of β‐spherulites, and the spherulitic size decreased in the composites. PP‐g‐MAH improved the compatibility and adhesion between T‐CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T‐CSW, while the flexural modulus was weakened for β‐PP/T‐CSW and β‐PP/PP‐g‐MAH/T‐CSW composites versus PP/T‐CSW composites. POLYM. COMPOS., 37:2121–2132, 2016. © 2015 Society of Plastics Engineers     

Preparation and characterization of β‐cyclodextrin‐linked chitosan microparticles

Hydrophobically modified chitosan containing β‐cyclodextrin (CD) units was synthesized by using tosylated β‐CD. The final product was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis and TGA, and rheometry. The polymer bearing β‐CD moieties was used to obtain crosslinked microparticles by spray‐drying which could then be used in a controlled release system for drugs. FTIR confirmed the formation of an amide linkage between cyclodextrin and chitosan. As fluorescence spectroscopy demonstrated, hydrophobic microenvironments were formed by chitosan bearing cyclodextrin in solution at lower concentrations than for chitosan. Rheometry and FTIR showed the crosslinking of the new polymer using genipin, a molecule of natural origin. Microspheres (MS) obtained by spray‐drying showed narrow size distribution when β‐CD was grafted onto chitosan and ξ‐potential of MS was slightly lower although it remained positive. In conclusion, β‐CD linked chitosan polymer can be considered as a very promising controlled drug delivery system for drugs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adsorption and drug release based on β‐cyclodextrin‐grafted hydroxyapatite composite

In this study, β‐cyclodextrin (β‐CD) was covalently grafted on hydroxyapatite (HA) using a coupling agent to improve the drug loading capacity and prolong the drug release. The binding of β‐CD on the HA surface was confirmed by Fourier transformation infrared spectroscopy, thermal gravimetric analysis, and X‐ray powder diffraction. The adsorption capacity of ofloxacin on β‐CD‐grafted hydroxyapatite (β‐CD‐g‐HA) composite was found to be 30 mg g^?1 at 37°C and 24 h. The adsorption process is spontaneous, given the negative values of free energy change. Compared with the release of ofloxacin loaded on HA, the release of ofloxacin loaded on β‐CD‐g‐HA was slowed down 28% and 21% in pH 2.0 and pH 7.4 buffer media at 2 h, respectively. Biocompatibility of β‐CD‐g‐HA was assessed by MTT assay, and the result showed that it had no cytotoxicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of carbon nanotube‐supported β nucleating agent on the thermal properties,morphology, and mechanical properties of polyamide 6/isotactic polypropylene blends

A new kind of β nucleating agent, multi‐wall carbon nanotube (MWCNT)‐supported calcium pimelate was introduced into polyamide 6 (PA 6)/isotactic polypropylene (iPP; 10/90 by weight) blend and the thermal properties, morphology, and mechanical properties were investigated. The results showed that β‐iPP appeared at low content of MWCNT‐supported calcium pimelate which surmounted the α‐nucleating effect of PA 6 for iPP, and the content of β‐iPP increased with increasing content of MWCNT‐supported calcium pimelate. The impact strength, elongation at break, and flexural modulus were improved with increasing content of MWCNT‐supported calcium pimelate without significantly deteriorating the tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of β‐SiCw/BDM/DBA composites with excellent comprehensive properties

Functionalized β‐SiC whiskers (β‐SiCw) are employed to prepare β‐SiCw/N,N′‐4, 4′‐bimaleimide diphenyl methane/diallylbisphenol A (β‐SiCw/BDM/DBA) composites via powder blending‐casting method. The thermal conductive coefficient of the β‐SiCw/BDM/DBA composites is 0.994 W/mK with 40 wt% functionalized β‐SiCw, five times higher than that of pure BDM/DBA. The mechanical properties of the β‐SiCw/BDM/DBA composites are optimal with 10 wt% functionalized β‐SiCw. Both thermal resistance and dielectric constant are increased with the increasing addition of β‐SiCw. For a given β‐SiCw loading, the surface functionalization of β‐SiCw exhibits a positive effect on the thermal conductivities and mechanical properties of the β‐SiCw/BDM/DBA composites. POLYM. COMPOS., 35:1875–1878, 2014. © 2014 Society of Plastics Engineers     

Effect of N,N′‐diphenyl adipamide on the formation of the β‐crystalline form in isotactic polypropylene

The polymorphic compositions and mechanical properties of isotactic polypropylene (iPP) samples nucleated by a selective β‐nucleating agent [N,N′‐diphenyl adipamide (DPA)] were investigated with wide‐angle X‐ray diffraction, polarized light microscopy, scanning electron microscopy, and mechanical tests. It was found that β‐phase crystals emerged with the addition of DPA, and the relative proportion of the β‐crystalline form reached the maximum value of 0.97 with the addition of 0.1 wt % DPA. The curved lamellae in the β spherulites were like flowers. The β spherulites were etched more easily than α spherulites because amorphous regions were distributed inside the β spherulites. The Izod notched impact strength increased sharply with the addition of DPA and attained the maximum value of 7.30 kJ/m² (the value of blank iPP was 3.13 kJ/m²) with the addition of 0.1 wt % DPA. An analysis of the misfit factors between DPA and β‐iPP showed that β‐iPP could epitaxially crystallize on the DPA crystal well. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A highly active and selective β‐nucleating agent for isotactic polypropylene and crystallization behavior of β‐nucleated isotactic polypropylene under rapid cooling

Zinc adipate (Adi‐Zn) was observed to be a highly active and selective β‐nucleating agent for isotactic polypropylene (iPP). The effects of Adi‐Zn on the mechanical properties and the β‐crystals content of nucleated iPP were investigated. The impact strength of iPP nucleated with 0.2 wt % Adi‐Zn was 1.8 times higher than that of neat iPP. In addition, wide‐angle X‐ray diffraction analysis indicated that the content of β‐crystals in nucleated iPP (k_β value) reached 0.973 with 0.1 wt % Adi‐Zn, indicating that Adi‐Zn is a highly active and selective β‐nucleating agent for iPP. Furthermore, fast scanning chip calorimetry (FSC) studies using cooling rates from 60 to 13,800 °C min^?1 revealed that the formation of β‐crystals significantly depended on the cooling rates. At cooling rates below 3000 °C min^?1, only β‐crystals existed. However, at cooling rates above 6000 °C min^?1, β‐crystals failed to form. Moreover, a lower critical crystallization temperature that corresponded to the generation of β‐crystals was investigated using cooling‐induced crystallization, and the results are in good agreement with those of a previous study. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43767.     

Simultaneously improving the toughness,flexural modulus and thermal performance of isotactic polypropylene by α‐β crystalline transition and inorganic whisker reinforcement

Magnesium salt (M‐HOS) whisker and β‐nucleating agent were introduced into polypropylene and their effects on the crystalline structures, morphologies, mechanical properties, and thermal resistance of polypropylene (PP) were investigated. The results of wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and polar optical microscopy (POM) examinations suggested that the presence of the whisker did not cause any negative effect on the occurrence of β‐modification, and β‐phase became absolutely dominant form in β‐nucleated samples. The mechanical and thermal properties tests demonstrated that there is an excellent synergy between the β‐nucleating agent and the whisker. For PP composite containing 0.1 wt% of the β‐nucleating agent and 10 wt% of the whiskers, the Izod notched impact strength, elongation at break, flexural modulus, and heat deflection temperature were increased by 108, 194, 31, and 40%, respectively, compared with those of neat PP. By combining the toughening effect of α–β transition with the reinforcing effect of the whisker, simultaneous improvement in toughness, flexural modulus, and thermal performance of PP was successfully achieved. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Pervaporation behavior of PVA membrane containing β‐cyclodextrin for separating xylene isomeric mixtures

To evaluate molecular recognition function of β‐cyclodextrin to xylene isomers, β‐CD polymer of branching chain extension (β‐CD‐EGDE) was synthesized by crosslinking β‐CD with ethylene glycol diglycidyl ether (EGDE). The pervaporation blend membranes of β‐CD‐EGDE/PVA were prepared by casting an aqueous solution of PVA and β‐CD polymer mixture, and the membranes were used for separation of p‐/m‐ and p‐/o‐xylene mixtures. It was observed that the pristine PVA membrane almost had no selectivity for xylene isomer mixtures. The PVA membrane incorporating β‐CD polymer had molecular recognition function, which selectively facilitated the transport of the xylene isomers. To ascertain pervaporation behavior, the sorption and desorption processes of the membrane in xylenes were investigated. The sorption result showed that the complex formation constant between β‐CDs and xylenes played a key role in swelling behavior. There was a significant difference between diffusion coefficients D and D⁰, calculated from the sorption and desorption measurements, respectively, indicating that the diffusivity selectivity in desorption stage may have remarkable effect on the total selectivity during pervaporation process. © 2012 American Institute of Chemical Engineers AIChE J, 59: 604–612, 2013     

A highly efficient β‐nucleating agent for impact‐resistant polypropylene copolymer

In this work, we reported calcium tetrahydrophthalate as a high efficient β‐nucleating agent (β‐NA) for impact‐resistant polypropylene copolymer (IPC). The relative fraction of the β‐crystal can reach as high as 93.5% when only 0.03% β‐NA is added. The non‐isothermal and isothermal crystallization behaviors, morphology, lamellar structure and mechanical properties of IPCs with various β‐NA contents were studied. During non‐isothermal crystallization, the cooling rate has an important influence on the relative fraction of the β‐crystal, which decreases remarkably as the cooling rate increases. The β‐NA also greatly accelerates crystallization rate of IPC, resulting from both more crystal nuclei and larger Avrami exponent. The small angle X‐ray scattering characterization shows that more amorphous components are included into the inter‐lamellae after addition of β‐NA. Dynamical mechanical analysis (DMA) reveals that the storage modulus at low temperature and the loss factor above 0 °C from the PP component can be enhanced upon addition of β‐NA and reach a maximum at the β‐NA content of 0.05 wt %. Impact test shows that the impact strength of the IPC at 0°C can be improved as much as 40% when the content of calcium tetrahydrophthalate is 0.10 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40753.     

Nano‐Hydroxyapatite Improves the Properties of β‐tricalcium Phosphate Bone Scaffolds

β‐Tricalcium phosphates have been widely used as biomaterials for bone substitutes; however, the poor mechanical properties limit the application in bearing loading bones. In this study, nano‐hydroxyapatite has been introduced to improve the mechanical properties for porous bioceramic scaffolds. Nanocomposites containing 0–10 wt% needle‐like nano‐hydroxyapatite were prepared for investigation. It has been found that needle‐like nano‐hydroxyapatite improves the toughness, hardness, and compressive strength of the porous β‐tricalcium phosphates scaffolds, as well as the microstructure properties. The study provides a reference for the development of safe, excellent bone scaffolds for bone tissue engineering.