Rheokinetic studies and compressive response of high performance polybenzoxazine syntactic foams

The growing need for high thermal and mechanical resistant lightweight syntactic foams demands the designing of new materials. Herein, we report the successful fabrication of lightweight and high thermal resistance syntactic foams with excellent thermal and good mechanical properties. For this end, 10–50 wt% hollow glass microsphere (HGMS) containing polybenzoxazine based syntactic foams were prepared by using bisphenol‐A‐aniline (BA‐a) and phenol‐diaminodiphenylmethane (P‐ddm) benzoxazine via curing at 10 MPa compression molding. The curing behavior, tensile, flexural, compressive, and impact strength, thermal properties, and fracture morphology of the syntactic foams were studied by DSC, universal material testing machine, and drop hammer impact testing machine, TGA, and SEM, respectively. The curing temperatures of BA‐a and P‐ddm benzoxazine resins were slightly increased after blending the HGMS. The highest decline (59%) in the density and highest void contains (13.17%) was recorded for the poly(P‐ddm/HGMS50) sample. The excellent specific mechanical properties of the syntactic foams were observed on the 30 wt% HGMS loading. The thermal conductivity of the foams was gradually decreased and the lowest values of 0.106 and 0.0985 W/m.K were observed for poly(BA‐a/HMGS50) and poly(P‐ddm/HGMS50) sample, respectively. Furthermore, a gradual improvement in the thermal properties was observed as the loading of HGMS increased.

Section: Resultsmentioning

confidence: 99%

Effects of hollow glass microspheres on the polybenzoxazine thermosets: Mechanical, thermal, heat insulation, and morphological properties

Kiran

Gorar

Wang

et al. 2021

“…Detailed rheological studies on microballoon-polymer resin systems have been discussed elsewhere. 14,15 A representative increases in viscosity of the silicone resin due to introduction of HGMs is presented in Figure 2. It can be seen that the viscosity increases nonlinearly upon addition of microballoons and solventless processing of formulations is practically impossible at microballoon loadings >40%.…”

Section: Density Of Syntactic Foamsmentioning

confidence: 99%

Flexible silicone‐hollow glass microballoon syntactic foams for application in fire protective clothing

Tripathi

Parthasarathy

Yadav

et al. 2022

Self Cite

This work deals with the development of flexible syntactic foams based on silicone and hollow glass microballoons (HGMs) for potential application as a lightweight thermal cum vapor barrier in fire-protective ensembles. HGMs offer excellent thermal insulation and their inclusion into silicone leads to significant weight reduction, while improving the level of protection. Flexible silicone foams containing different types and loadings of HGMs were prepared and it was observed that high-density microballoons (K46) survived compression molding process, due to their superior crushing strength (6000 psi) as compared to K15 (300 psi). The specific quasi-static mechanical properties increased proportionally to the extent of loading. The inclusion of HGMs did not alter the curing behavior of silicone resin. Syntactic foams (40% HGMs) were coated onto glass fabric (GF) to prepare composites and thermal protective performance tests were performed to establish their effect on heat transfer. The protection level was higher for syntactic foam containing K46 glass microballoons, as compared to K15. The second-degree burn time increased from 6.4 s (neat GF) to 10s for syntactic foam-coated GF. Our studies demonstrate the potential of the developed syntactic foam-coated GFs as a vapor cum thermal barrier in fire protective clothing.

“…The mechanical properties of syntactic composites can be tailored by varying different parameters such as matrix, microsphere size, wall thickness and volume fraction, among others 7,17–22 . Significant experimental studies have been conducted on enhancing the mechanical properties of syntactic foams by reinforcement with fibers 23–29 and some nanoparticles 30–32 …”

Section: Introductionmentioning

confidence: 99%

Mechanical behavior of glass fiber‐reinforced Nylon‐6 syntactic foams and its Young's modulus numerical study

Yáñez‐Macías¹,

Rivera-Salinas²,

Solís-Rosales³

et al. 2021

Glass fiber‐reinforced Nylon‐6 syntactic foams (GRSF) were fabricated by melt mixing, adding silane‐modified hollow glass microspheres (HGMf) at 5, 10, 15, and 20 wt% and an impact modifier at 15 wt. Tensile test results showed that the foam's strength increased with the addition of HGMs but started to decrease when the volume fraction of the spheres was higher than 18 vol% (10 wt%). To elucidate the reinforcement mechanism, a numerical simulation of GRSF was carried out. It revealed that HGMs progressively become the reinforcement phase of GRSFs, as their volume fraction increased due to the load transfer occurring more readily in the HGMs than the fiber, which is expected to be the reinforcement. Hence, for a desired weight‐strength ratio, thicker walls are necessary to delay the elastic relaxation of the microspheres and the impairing of the composite as a whole in the context of strength. HGMs with relative wall thickness τ = 0.04 produce an impairing on Young's modulus, if the volume fraction of microspheres is exceeded than 18 vol% because the microspheres are not able to endure increased loads. In addition, a significant reduction of the density was observed by up to 12% in the GRSFs with 30 wt% of both fibers and HGMs. The insight gained of GRSFs role and the numerical simulation achieved through this work, is a significant step toward developing applications of these lightweight materials, since they show good combination of strength, toughness, density, and thermal insulation performance, which can be useful in the automotive, aeronautical and sports industries.