Mechanical Properties Of Glass Fiber

Properties of glass fiber reinforced plastic equipment, especially its physics, mechanical properties and glass fiber and its products performance and glass fiber and its products of performance, varieties, specifications have a direct relationship. In chemical corrosion resistance, because the glass fiber is superior to synthetic resin, so in addition to the individual case, mainly depends on the corrosion resistance of the resin.

Mechanical properties: glass fiber is characterized by high tensile strength and specific strength.

It is generally believed that the tensile strength of glass fiber is related to the diameter and the length of the sample. Usually it is natural or chemical fiber high 5~30 times, 2 times higher than that of steel.

The proportion of glass fiber is small, is 2.5~2.7, is bigger than the natural or chemical fiber, is about the steel 1/3.

Glass fiber is an excellent elastic material, the stress and strain diagram is a straight line. The maximum elongation at break is related to the diameter of the fiber, but generally not more than 5%.

The modulus of elasticity is equal to that of pure Al. Only the 1/3~1/6 of the steel, which can be described as the biggest weakness of the glass fiber.

Glass fiber is more brittle and durable.

Source: www.unicomposite.com

Pultrusion Resin For Fiberglass Windows And Doors

Fiberglass pultruded window and door profiles are not the same as many general FRP products, they have multi-cavity and very thin wall thickness. Today we'll talk about the basic requirements of the pultrusion resin for the multi-cavity and thin-walled profile in high speed production:

(1) high reactivity;

(2) high glass temperature;

(3) the speed of saturation should be as high as possible;

(4) the proper viscosity characteristic.

Low reactive resin has slow speed reaction, even in the pultrusion mold for very short residence time and is unable to complete curing reaction, cementitious area will be too long, production difficulties: to regulate the reaction activity of the matrix resin, selection of appropriate initiator or choose a variety of initiator trigger.

Isophthalic resin glass transition temperature is high, the gelation time is short and the gel strength is higher, easily impregnated fiber and moderate viscosity (500 ~ 600 centipoises), packing is not easy to sink, very suitable for production of multi cavity thin wall material with special shape.

In order to improve the pultrusion speed and shorten the time of gelation, we should use the multi - level initiating system caused by low temperature, medium temperature and high temperature so that the resin matrix can be initiated at a lower temperature. In order to guarantee the inner and outer resin matrix can simultaneously cure, eliminate the crack and the profile bending phenomenon due to the curing time of the inside and outside resin matrix, adopt this system. It can also shorten the time of gelation. To improve the strength of the gel, and reduce the occurrence of the accident rate. The surface quality of the profiles can be improved by improving the tension speed and increasing the degree of curing.

                                                                                                     Source: www.unicomposite.com

Carbon Fiber Material Characteristics

There are two common types of carbon fiber products production process, pultrusion and roller. Carbon fiber materials and other strengthening materials comparision: (1) tensile strength: carbon fiber tensile strength is about 10 times than steel. (2) the tensile modulus of the carbon fiber composites is higher than that of the steel, but the tensile modulus of the aramid fiber and glass fiber composites is only half and 1/4 of the steel. (3): fatigue strength of carbon fiber pultruded and aramid fiber composite material fatigue strength is higher than that of a high strength. The fatigue limit of the metal materials is only 30% ~ 40% of the static load, under the action of alternating stress.. Due to the fiber and the matrix composite can ease the crack extension, and possibility of the existence of the internal force redistribution of fiber, composite fatigue limit is higher, about static load strength of 70% ~ 80%, and in front of the destruction of a significant signs of deformation. (4) weight: about 1/5 of the steel. (5) the comparison with carbon fiber board: carbon fiber sheet can be pasted on the structural surface of various shapes, and the plate is more suitable for the surface of a rule member. In addition, because of the adhesive strength of the adhesive layer, the amount of resin is more thick and the adhesive strength of the adhesive layer is better than that of the concrete interface.

                                                                                   Source: www.unicomposite.com

The Relationship Between Pultrusion And Molded Craft

In many different kinds of fiberglass products, it has the highest similarity between molding FRP grating and pultrusion product. It’s different from molded craft, while produce FRP grating by pultrusion technology. FRP pultrusion technology is a assembly by bars, but the molding craft is not. You get the only product ,while using the only mould.

The same features between mold craft and FRP pultrusin technology:

They are both the FRP production craft, also the product produced by those two ways can be combined. For example, when we install the operating platform, the key bars are FRP grating, but minor bars are pultrusion technology product, such as FRP  holder, FRP square tube and channel, bars and so on. In a word, the most similarity between them is supplement each other.

The differents features between molded craft and FRP pultrusin technology:

Relative to the similarity, the difference will be more.

1.The feature

pultrusion technology: fast production, easy operation, good variability(just change the mould, while produce the new production). As a result, the kind of pultrusion technology product is more than molding craft product.

Molded craft: the weakness is mainly aritificial operation, a waste of time, the mold can’t be changed, single product shape. But the advantage is stable property and durability.

2.Theory of production

Pultrusion technology product is produced by semi-automatic equipment, fast and easy operation, while the molding craft bars is made by aritificial operation, a waste of time and complex operation.

3. Usage

they have different range and occasion of usage. For example, FRP bridge is made of pultrusion technology bars, but fiberglass molded grating can’t achieve it.

                                                                                                 Source: www.unicomposite.com

Pultrusion Process Parameter Control Element

Because the pultrusion process parameters to pull the thermosetting resin, by some complex factors which occurred in the mold of the constraints, and also by mutual influence between the other parameters, therefore in the pultrusion process, polymerization reaction of raw materials, and it is more difficult to accurately forecast.

At present, FRP pultrusion mould used in the monitoring and control of the sensing element has: temperature sensor, pressure sensor and the dielectric sensor three of the sesensors, must first solve the problem of wear resistant pultrusion. In addition, temperature,volume fraction of FRP mould, and the pulling speed, also will have a certain impact on the pultrusion molding process parameter sensor.

The current commonly used FRP pultrusion equipment, temperature sensing detection ofthe elements, often along the fiber direction, the surface area and placed in the forming mold, and the pressure sensing element, the middle position is often placed at the entrance of the pultrusion mould (usually pultrusion mould length 1000mm). The surface tension type pressure sensing element, often coated with chromium layer, in order to improve its performance of pultruded profiles wear resistance.

                                                                                                Source: www.unicomposite.com

FRP Products Fire Retardant Standards

Some fiberglass pultruded profiles applications require the fire retardant property, and different fire retardant rates have different functions. Two types of North America and Europe fire retardant standards are listed below:

1. ASTM E 84 

It is standard test method for surface burning characteristics of of building materials. 

The flame spread index and smoke developed index values obtained by the ASTM E 84 test are used by code officials and regulatory agencies in the acceptance of interior finish materials for various applications. The most widely accepted classification system is described in the National Fire Protection Association publication NFPA 101 Life Safety Code 

1. 2006 International Building Code 

a. Section 803 Wall and Ceiling Finishes, Paragraph 803.1 General states, “Interior wall and ceiling finishes shall be classified in accordance with ASTM E- 84.Such interior finish materials shall be grouped in the following classes in accordance with their flame spread and smoke-developed indexes. 

i. Class A: Flame Spread 0-25; smoke-developed 0-450 ii. Class B: Flame Spread 26-75; smoke-developed 0-450 iii. Class C: Flame Spread 76-200; smoke-developed 0-450 

Class A,B, and C correspond to type I, II, and III respectively in other codes such as SBCCI, BOCA, ICBO. They do not preclude a material being otherwise classified by the authority of jurisdiction.

2. UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing is a plastics flammability standard released by Underwriters Laboratories of the USA.

The standard classifies plastics according to how they burn in various orientations and thicknesses. From lowest (least flame-retardant) to highest (most flame-retardant), the classifications are:

HB: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm and burning stops before 100 mm

V-2 burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.

V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.

V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.

5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.

5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole

Tests are generally conducted on a 5" x 1/2" (12.7 cm x 1.27 cm) specimen of the minimum approved thickness. For 5VA and 5VB ratings, tests are performed on both bar and plaque specimens, and the flame ignition source is approximately five times as severe as that used for testing the other materials.

There are other classifications that apply to low density foam materials (HF-1, HF-2, HBF) and thin films (VTM-0, VTM-1, VTM-2).

HF-1: burning stops within 2 seconds; afterglow less than 30s; no burning drips allowed.

HF-2: burning stops within 3 seconds; afterglow less than 30s; burning drips allowed.   From Widipedia

                                                                                                         Source: www.unicomposite.com

Types Of FRP Gratings

According to the forming process, fiberglass gratings can be divided into pultruded fiberglass gratings and molded fiberglass gratings.

Pultruded Gratings:

Pultruded FRP gratings are assembled by three parts:

Bearing profile: it is mainly composed of pultruded "I" or "T" profile.

The connection profile: its role is to connect the bearing section, and it is mainly used inpultrusion rod or a variety of special stick

The spacer profile: its role in the regulation of the gap and fixed fiberglass gratings, it is mainly used for pultrusion of bar

With pultruded profile "I" or "T" profile bearing rod, with pultruded rod or bar as various shaped bar with adhesive, according to a certain pitch of the bar and the bearing rod are connected together to form the FRP gratings.

Molded FRP gratings: laying glass fiber roving in large metal mold casting with thermosetting resin, and a cold curing molding, mold release can be obtained after the molding of FRP gratings. In the production of molded grating, we can seal the surface of gratings wtih upper plate structure to form gratings at lower height.

The FRP gratings color: color is compatible with the resins and resin paste to achieve, so the color is not on the surface, so as to keep the lasting color. Colorful FRP gratings can improve your production environment, change the invariable gloomy situation corrosive environment and make your factory modern.

                                                                                              Source: www.unicomposite.com