crystSG {cryst}

Relative Crystallinity Calculation of X-Ray Diffraction Pattern of Starch by Frost Method

Description

Allow to calculate the relative crystallinity of starch by XRD. The basic concept of Frost approach involves obtaining a smoothed line that separates the amorphous and crystalline starch of an X-ray diffraction pattern. This smoothed line is achieved by applying a Savitzky-Golay smoothing method to the original pattern.

Usage

crystSG(pattern, N = 101, iter = 400, p = 2)

Arguments

pattern

matrix. The matrix of X-ray diffraction pattern. The first row corresponds to Bragg angle 2\theta; the second row corresponds to intensity.

N

numeric. N length of the smoothing window (number of variables). Defaults to 101.

iter

numeric. Iter number of iterations. Defaults to 400.

p

numeric. Filter order. Defaults to 2.

Details

Calculate the relative starch crystallinity of XRD pattern by Frost method.

Value

An object of class crystSG, which is a list with the following components:

original

Original matrix of X-ray diffraction patterns.

background

Estimation of the background shape (curve of the amorphous starch).

corrected

Estimation of residual crystalline area (curve of the crystalline starch).

summary

Summary calculation of crystallinity. Total area under the curve of the diffraction pattern (A.U.); Amorphous area (A.U.); Crystalline area (A.U.); Relative crystallinity (%).

Author(s)

Claudio Pozo Valenzuela [aut, cre] and Saddys Rodriguez-llamazares [aut]

References

Frost, K., et al. (2009). "Crystallinity and structure of starch using wide angle X-ray scattering." Carbohydrate Polymers 78(3): 543-548.

Examples

data(XRD)
# Convert data frame to matrix, select A-type starch
pattern <- as.matrix(t(XRD[, c("Bragg_angle","A")]))
# List of crystallinity components
crs <- crystSG(pattern, N = 101, iter = 400, p = 2)
# Original matrix
original <- crs$original
# Background shape
background <- crs$background
# Curve of the crystalline starch
corrected <- crs$corrected
# Summary calculation of crystallinity
summary <- crs$summary