Preparation and properties of maleimide‐functionalized hyperbranched polysiloxane and its hybrids based on cyanate ester resin

Abstract

A new hyperbranched polysiloxane containing maleimide (HPMA) was synthesized through the reaction between N-(4-hydroxyphenyl) maleimide and 3-glycidoxypropyltrimethoxysilane, which was then used to prepare cyanate ester (CE) resin-based hybrids (coded as HPMAx/CE, where x is the weight fraction of HPMA in the hybrid). The curing behavior of uncured hybrids and the typical properties (impact strength and dielectric properties) of cured hybrids were systemically investigated. Results show that the performance of hybrids is greatly related with the content of HPMA. Hybrids have obviously lower curing temperature than CE, overcoming the poor curing characteristics (higher curing temperature and longer curing time) of neat CE, for example, the curing peak temperature of HPMA20/CE is about 65 C lower than that of CE. In the case of cured resin and hybrids, the hybrids exhibit decreased dielectric constant and loss than CE resin; moreover, the former also exhibits lower water absorption than the latter. Specifically, the dielectric loss of HPMA15/CE hybrid is only about 27% of that of neat CE resin. In addition, the hybrids with suitable contents of HPMA have significantly improved impact strengths. The overall improved properties suggest that HPMAx/CE hybrids have great potential in applications needing harsh requirements of curing feature, dielectric properties, and toughness. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: [205][206][207][208][209][210][211][212][213][214][215] 2012

Curing kinetics and mechanical properties of cyanate ester/hyperbranched benzoxazine copolymers

“… where T r is the absolute temperature of the sample in the rubbery state, here is a temperature 40°C higher than T g , E r is the storage modulus at T r , R is the gas constant, and v e corresponding to cured CE, CE/P‐a‐3, and CE/HB‐3 is shown in Figure 9. The crosslink density of CE/HB‐3 was lower than the corresponding values for the poly(CE) but higher than CE/P‐a‐3.Compared with the results in the literature, 3,41,42 these results are reasonable.…”

DMA testing of epoxy resins: The importance of dimensions

“…If multiple values were presented in a paper, only the highest and lowest were compiled. In some circumstances, it was difficult to ascertain the basic parameters surrounding the DMA tests; researchers occasionally omitted sample dimensions , the clamp type used , the test span , or appear to report the test span as the total length of a sample . Given a limited number of clamps available, actual sample spans were inferred from stated sample lengths, e.g., a sample described to be a 60 mm DC sample was interpreted to be a 60 mm sample tested in the 35 mm DC clamp.…”

“…The DMA instrument manufacturers do suggest sample dimension ranges for given geometries , but do not discuss how a three order of magnitude modulus change through the glass transition can affect DMA measurements. Numerous researchers favor the 3pt bend geometry , other favor the DC geometry , and others favor the SC geometry . However, Duncan and others claim that the 3pt bend geometry is best suited for high modulus materials, such as metals, ceramics, and highly filled thermosetting polymers that show little change in modulus throughout the test .…”

Tough epoxy/cyanate ester resins with improved thermal stability, lower dielectric constant and loss based on unique hyperbranched polysiloxane liquid crystalline

“…The microscopic properties of a thermosetting resin are determined by its structure including polymer chain structure and aggregation structure, the former is reflected by the curing mechanism and the latter is characterized by crosslinking density ( X density ), free volume and molecular interaction …”