Preparation and properties of LGF/ER/TPU/PMMA composites

Qin

et al. 2016

Polymer Composites

Self Cite

Long glass fibers reinforced thermoplastic polyurethane and poly(butylene terephthalate) with the compatibilizer of poly(ethylene-butylacrylate-glycidyl methacrylate copolymer) (LGF/TPU/PBT/PTW) composites were prepared by using self-designed impregnation device. Various rheological plots including viscosity curve, storage modulus, loss modulus, loss angle, Cole-Cole plot, and relaxation spectrum were used to characterization of rheological properties. Dynamic mechanical thermal analysis (DMA) results indicated that "double tan d behavior" of composites is observed. The activation energies of a and b-relaxation process of loss modulus and tan d of the LGF/TPU/PBT/ PTW composites gradually increased with long glass fibers content. Moreover, activation energies for the glass transition relaxation determined from loss tangent peaks are more reliable than using loss modulus criterion. Thermal properties of composites are studied by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). Mechanical properties of composites are studied. POLYM. COMPOS., 39:794-806, 2018.

Section: Resultscontrasting

confidence: 67%

Rheology characterization, dynamic mechanical, thermal, and mechanical properties of LGF/TPU/PBT/PTW composites

Qin

et al. 2016

Polymer Composites

Self Cite

“…The later can also be considered as representing the energy barrier for the relaxing of glass transition. 31 First, the molecular relaxation time can be described according to the classical Arrhenius equation 32…”

Section: Resultsmentioning

confidence: 99%

The evolution of morphology, crystallization and static and dynamic mechanical properties of long glass-fibre–reinforced polypropylene composites under thermo-oxidative ageing

Journal of Thermoplastic Composite Materials

et al. 2018

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In this work, the static and dynamic mechanical properties, crystallization behaviours, and morphology of long glass-fibre–reinforced polypropylene (PP) composites with thermo-oxidative ageing time from 0 day to 50 days at 120°C were investigated and discussed. The static mechanical properties showed a global decrease in tensile, bending and impact strengths with increasing ageing time. From the results obtained by scanning electronic microscopic observations, interface debonding clearly occurred between the glass fibre and PP matrix in the aged samples. The crystallinity ( Xc) of the composites was analyzed by differential scanning calorimetry; annealing process played the leading role in the early period of ageing, while as ageing progressed, the degradation of PP matrix dominated the ageing process and Xc decreased. The dynamic mechanical analysis results indicated that the storage modulus and glass transition temperature of the composites also decreased with prolonging ageing time. Then, the apparent activation energy ( E) of glass transition was calculated by the Arrhenius equation with different scanning frequencies. A higher value of E was obtained for the samples in the later ageing period, which means a higher energy barrier for glass transition.

“…A similar increase in storage modulus of the polymer composites because of the increasing test frequencies were also reported by some researchers. 21,23,24 From Table 1, the storage modulus of LGF/PBT composites rstly increases and then decreases with the length of the original glass ber increase.…”

Section: Dma Analysis Of Lgf/pbt Compositesmentioning

confidence: 98%

Effect of fiber length and dispersion on properties of long glass fiber reinforced thermoplastic composites based on poly(butylene terephthalate)

Qin

et al. 2017

RSC Adv.

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Long glass fiber reinforced poly(butylene terephthalate) (LGF/PBT) composites with different original glass fiber lengths were prepared using a impregnation device designed by the authors. The influence of fiber length and fiber distribution on the properties of the LGF/PBT composites were studied. The results showed that the length of the residual glass fibers increased with the original glass fiber length increase of LGF/PBT composites. Scanning electron microscopy results indicated that the glass fibers of LGF/PBT composites (16 nm and 20 mm) were unevenly dispersed and this is a phenomenon of their reunion in the resin matrix. Various rheological plots including viscosity curve, storage modulus, loss modulus, and loss angle, were used to characterization the rheological properties of the pristine matrix and the LGF/PBT composites. Dynamic mechanical thermal analysis results indicated that the storage and loss modulus of the LGF/PBT composites firstly increase and then decrease with original glass fiber length. The storage and loss modulus, glass transition temperatures of the pristine matrix and LGF/PBT composites increase with test frequencies increase. The activation energies of glass transition relaxation for the activation energies for loss tangent (tan d) and loss modulus (E 00 ) peaks were calculated. Furthermore, the glass transition relaxation determined from the tan d peaks were more reliable than using the E 00 criterion. Differential scanning calorimetry analysis indicated that the crystallization temperature (T c ), percentage crystallinity (X c ) and melting point of the LGF/PBT composites firstly increased and then slightly decreased with the increase of the original glass fiber length. Thermogravimetry (TG) and differential thermal gravimetric analysis curves of the LGF/thermoplastic polyurethane (TPU)/PBT/polyethylene-butylacrylate-glycidyl methacrylate (PTW) composites were shifted to higher temperatures with the increase of the LGF content.Thermogravimetric analysis results showed that the TG curves of the LGF/TPU/PBT/PTW composites firstly shifted to higher temperatures and then shifted to lower temperatures as the original glass fiber length increased. The limiting oxygen values of the pristine matrix and LGF/PBT composites showed little change, which indicated that the effect of the original glass fiber length on the combustion behavior of LGF/PBT composites was not obvious. The tensile strength, notched Izod impact strength, flexural strength and modulus of the LGF/PBT composites firstly increase and then decrease with the original glass fiber length.When the original glass fiber length was 12 mm, the mechanical properties of LGF/PBT composites were optimal.