Electrospun Polyamide Nanofiber-Reinforced Hybrid Syntactic Foams

J of Applied Polymer Sci

Roy

2017

The potential of preformed elastomers as a toughening agent for epoxy–glass syntactic foam has been explored. Poly(dimethylsiloxane) microspheres were prepared by suspension polymerization. The microsphere dimensions could be varied from 58 to 255 µm by tuning the reaction parameters, particularly the stirring speed and feed concentration. Rheological studies indicated that the introduction of microballoons led to an increase in the viscosity of the resin, with the extent being proportional to the microballoon content. The zero shear viscosity increased from ∼103 mPa s at 30 °C to 105 mPa s as the microballoon loading was increased to 40%. Syntactic foams containing varying amounts of microballoons (40–60% v/v) were prepared, and an analogous set of toughened foams were also prepared, where a fraction of the microballoons was replaced with poly(dimethylsiloxane) microspheres (3–7%). The effect of increasing dimensions of the elastomeric microspheres on the mechanical properties was also studied. The improvement in properties was more pronounced when the microsphere size was equivalent to that of the constituent microballoons. An improvement of 40% and 185% in flexural strength and flexural toughness was observed upon the introduction of poly(dimethylsiloxane) microspheres of optimal dimensions (diameter ∼63 µm, 5% loading), without any undesirable increase in foam density. However, the compressive properties remained practically unaltered. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45882.

Section: Methodssupporting

confidence: 87%

Section: Preparation Of Syntactic Foamsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Poly(dimethylsiloxane)‐toughened syntactic foams

J of Applied Polymer Sci

Roy

2017

“…Epoxy based syntactic foams were prepared as per the procedure reported in the literature [10]. The processing steps are as follows: firstly, precalculated amounts of epoxy and hardener (mix ratio of 100:13 by weight) are weighed and mixed together in a suitable beaker for about 5 min.…”

Section: Processing Of Syntactic Foamsmentioning

confidence: 99%

“…Polymeric syntactic foams refer to a subclass of cellular material, where hollow fillers are dispersed within a mechanically robust polymeric matrix. Apart from the nature of the matrix, concentration and type of microballoon are critical parameters, which decide its final properties [10]. Amongst hollow fillers, glass microballoons (HGM) are most extensively used [11][12][13][14], due to their low coefficient of thermal expansion and chemical inertness.…”

Section: Introductionmentioning

confidence: 99%

Epoxy-Glass Microballoon Syntactic Foams: Rheological Optimization of the Processing Window

Advances in Polymer Technology

Roy

2019

Self Cite

In this paper, we discuss the chemorheology of epoxy based syntactic foams containing glass microballoons of varying density, with an aim of establishing the effect of microballoon loading on its processability. The primary objective is to determine the maximum microballoon loading that disperses uniformly in the resin without the aid of any diluent. The viscosity and dynamic mechanical properties of epoxy formulations containing varying amounts of glass microballoons were established by parallel plate rheometry. Our studies reveal that solventless processing of formulations with microballoon loading > 60% poses practical difficulties due to prohibitively high viscosities, although a packing efficiency of 74% is theoretically allowed in the case of hexagonal close packing. The presence of microballoons does not alter the curing mechanism. The mechanical properties of syntactic foams were inversely proportional to the loading and type of glass microballoons.

Rheokinetic studies and compressive response of high performance polybenzoxazine syntactic foams

Sharma

J of Applied Polymer Sci

et al. 2018

Self Cite

Polybenzoxazines are finding increasing usage in demanding applications where high temperature stability is required, especially in the field of aerospace. In this work, thermally stable bisphenol F-based polybenzoxazine [poly(BF-a)] syntactic foams containing varying volume fractions (30-60%) of hollow glass microballoons (HGMs) were prepared and their mechanical response in the quasistatic regime was established. The effect of introducing glass microballoons on the curing profile of benzoxazine resin was studied using both nonisothermal differential scanning calorimetry and rheometry. Temperature-sweep experiments were performed to arrive at the optimal processing window of the benzoxazine-glass microballoons formulations, particularly in terms of viscosity, gelation temperature, and time. Thermally accelerated ring-opening polymerization of the benzoxazine resin led to complete curing of the syntactic foam formulations, as assessed by calorimetric studies. The thermal degradation behavior of the poly(BF-a)/HGM was studied using thermogravimetric analysis. As expected, the density of the syntactic foam specimens decreased with increasing microballoon content. Maximal increase in the specific compressive properties of the poly(BF-a)/HGM samples was observed in formulations containing 40% volume fraction of glass microballoons.